Form SC TO-T - Tender offer statement by Third Party

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE TO

TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1)

OF THE SECURITIES EXCHANGE ACT OF 1934

THESEUS PHARMACEUTICALS, INC.

(Name of Subject Company (Issuer))

CONCENTRA MERGER SUB II, INC.

(Name of Filing Persons (Co-Offeror 1))

CONCENTRA BIOSCIENCES, LLC

(Name of Filing Persons (Parent of Offeror))

TANG CAPITAL PARTNERS, LP

(Name of Filing Persons (Co-Offeror 2))

TANG CAPITAL MANAGEMENT, LLC

(Name of Filing Persons (Co-Offeror 3))

Common Stock, Par Value $0.0001 Per Share

(Title of Class of Securities)

88369M101

(CUSIP Number of Class of Securities)

Kevin Tang

Concentra Biosciences, LLC

4747 Executive Drive, Suite 210

San Diego, California 92121

Tel. (858) 281-5372

(Name, Address and Telephone Number of Person Authorized to Receive Notices

and Communications on Behalf of Filing Persons)

Copies to:

Ryan A. Murr

Robert W. Phillips

Gibson, Dunn & Crutcher LLP

One Embarcadero Center Suite 2600

San Francisco, CA 94111

Check the box if the filing relates solely to preliminary communications made before the commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which the statement relates:

☒			third-party tender offer subject to Rule 14d-1.
☐			issuer tender offer subject to Rule 13e-4.
☐			going-private transaction subject to Rule 13e-3.
☐			amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results of the tender offer. ☐

If applicable, check the appropriate box(es) below to designate the appropriate rule provision(s) relied upon:

☐			Rule 13e-4(i) (Cross-Border Issuer Tender Offer)
☐			Rule 13d-1(d) (Cross-Border Third-Party Tender Offer)

This Tender Offer Statement on Schedule TO (this “Schedule TO”) relates to the offer (the “Offer”) by Concentra Merger Sub II, Inc., a Delaware corporation (“Purchaser”) and a wholly owned subsidiary of Concentra Biosciences, LLC, a Delaware limited liability company (“Parent”), to purchase all of the issued and outstanding shares of common stock, par value $0.0001 per share (“Shares”), of Theseus Pharmaceuticals, Inc., a Delaware corporation (“Theseus”), for (i) $3.90 per Share in cash (the “Base Price Per Share”), (ii) an additional amount of cash of up to $0.15 per Share (such amount as finally determined pursuant to the Merger Agreement (as defined below), the “Additional Price Per Share” and together with the Base Price Per Share, the “Cash Amount”), and (iii) one non-transferable contractual contingent value right for each Share (each, a “CVR,” and each CVR together with the Cash Amount, the “Offer Price”), all upon the terms and subject to the conditions described in the Offer to Purchase and in the related Letter of Transmittal, copies of which are attached hereto as exhibits (a)(1)(A) and (a)(1)(B), respectively. Accordingly, the total Cash Amount that Purchaser may pay pursuant to the terms of the Offer and Merger Agreement is between $3.90 and $4.05 per Share. The Offer is being made pursuant to the Agreement and Plan of Merger, dated as of December 22, 2023 (together with any amendments or supplements thereto, the “Merger Agreement”), among Theseus, Parent and Purchaser, a copy of which is filed as Exhibit (d)(1) hereto and incorporated herein by reference with respect to Items 4 through 11 of this Schedule TO. Capitalized terms used but not otherwise defined herein have the meanings ascribed thereto in the Merger Agreement.

All of the information set forth in the Offer to Purchase is incorporated by reference herein in response to Items 1 through 9 and Item 11 of this Schedule TO, and is supplemented by the information specifically provided in this Schedule TO.

ITEM 1.

SUMMARY TERM SHEET.

The information set forth in the section of the Offer to Purchase titled “Summary Term Sheet” is incorporated herein by reference.

ITEM 2.

SUBJECT COMPANY INFORMATION.

(a) The subject company and the issuer of the securities subject to the Offer is Theseus Pharmaceuticals, Inc. Its principal executive office is located at 314 Main Street, Cambridge, Massachusetts 02142, and its telephone number is (857) 400-9491.

(b) This Schedule TO relates to the Shares. According to Theseus, as of the close of business on January 8, 2024, there were: (i) 44,649,172 Shares issued and outstanding; (2) 6,221,333 Shares subject to outstanding Company Stock Options, 3,033,530 of which were In-the-Money Options assuming the maximum potential Cash Amount of $4.05 per Share; and (3) 87,605 Shares subject to outstanding Company Restricted Stock Units.

(c) The information concerning the principal market on which the Shares are traded, and certain high and low sales prices for the Shares in the principal market in which the Shares are traded set forth in “Special Factors—Section 4. Price Range of Shares; Dividends” of the Offer to Purchase, are incorporated herein by reference.

ITEM 3.

IDENTITY AND BACKGROUND OF FILING PERSON.

(a)–(c) The filing companies of this Schedule TO, Parent, Purchaser, TCP (as defined below) and TCM (as defined below). Each of Purchaser’s, Parent’s, TCP’s and TCM’s principal executive office is located at 4747 Executive Drive, Suite 210, San Diego, California 92121. Each of Purchaser’s and Parent’s telephone number is (858) 281-5372. Each of TCP’s and TCM’s telephone number is (858) 200-3830.

Purchaser was incorporated under the laws of the State of Delaware on December 8, 2023 for the purpose of consummating the Offer and effecting the Merger pursuant to the Merger Agreement. Kevin Tang is the sole director and the executive officers of Purchaser are Mr. Tang, its Chief Executive Officer, Michael Hearne, its Chief Financial Officer, Ryan Cole, its Chief Operating Officer, Stew Kroll, its Chief Development Officer, and Thomas Wei, its Chief Business Officer. Each executive officer of Purchaser is a United States citizen and has a business address located at 4747 Executive Drive, Suite 210, San Diego, California 92121.

Parent was formed under the laws of the State of Delaware on March 8, 2023 and its principal business is currently to consummate the Offer and effect the Merger pursuant to the Merger Agreement, and to perform its obligations under the contingent value rights agreement, which is in substantially the form attached as Exhibit C

to the Merger Agreement (the “CVR Agreement”), following the Merger when Theseus is a wholly owned subsidiary of Parent as the surviving entity from the Merger. The executive officers of Parent are Mr. Tang, its Chief Executive Officer, Michael Hearne, its Chief Financial Officer, Ryan Cole, its Chief Operating Officer, Stew Kroll, its Chief Development Officer, and Thomas Wei, its Chief Business Officer. Each executive officer of Parent is a United States citizen and has a business address located at 4747 Executive Drive, Suite 210, San Diego, California 92121.

Tang Capital Partners, LP (“TCP”) was formed under the laws of the State of Delaware on August 16, 2002 and is the sole member of Parent. Its principal business is a life sciences-focused investment company.

Tang Capital Management, LLC (“TCM”) was formed under the laws of the State of Delaware on December 19, 2012. TCM is the sole manager of Parent and general partner of TCP. Its principal business is a life sciences-focused investment management company. Mr. Tang is the sole manager of TCM. The executive officers of TCM are Mr. Tang, its President, Michael Hearne, its Chief Financial Officer and Ryan Cole, its Chief Operating Officer. Each executive officer of TCM is a United States citizen and has a business address located at 4747 Executive Drive, Suite 210, San Diego, California 92121.

The information set forth in “The Tender Offer—Section 6. Certain Information Concerning Parent and Purchaser” and Schedule A—“Information Concerning Members of the Boards of Directors and the Executive Officers of Purchaser, Parent and the Guarantor” of the Offer to Purchase is incorporated herein by reference.

ITEM 4.

TERMS OF THE TRANSACTION.

(a)(1)(i)-(viii), (x), (xii), (a)(2)(i)-(v), (vii) The information set forth in the Offer to Purchase is incorporated herein by reference.

(a)(1)(ix), (xi), (a)(2)(vi) Not applicable.

ITEM 5.

PAST CONTACTS, TRANSACTIONS, NEGOTIATIONS AND AGREEMENTS.

(a), (b) The information set forth in “Special Factors—Section 1. Background of the Offer; Contacts with Theseus,” “Special Factors—Section 2. Purpose of the Offer and Plans for Theseus,” “The Tender Offer—Section 5. Certain Information Concerning Theseus,” “The Tender Offer—Section 6. Certain Information Concerning Parent and Purchaser” and Schedule A—“Information Concerning Members of the Boards of Directors and the Executive Officers of Purchaser, Parent and the Guarantor” of the Offer to Purchase is incorporated herein by reference.

ITEM 6.

PURPOSES OF THE TRANSACTION AND PLANS OR PROPOSALS.

(a), (c)(1)–(7) The information set forth in the sections of the Offer to Purchase titled “Summary Term Sheet” and “Introduction” and in “Special Factors—Section 2. Purpose of the Offer and Plans for Theseus,” “Special Factors—Section 5. Price Range of Shares; Dividends,” “Special Factors—Section 5. Possible Effects of the Offer on the Market for the Shares; Nasdaq Listing; Exchange Act Registration and Margin Regulations,” “The Tender Offer—Section 1. Terms of the Offer” and “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements” of the Offer to Purchase is incorporated herein by reference.

ITEM 7.

SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

(a), (d) The information set forth in the section of the Offer to Purchase titled “Summary Term Sheet” and in “The Tender Offer—Section 8. Source and Amount of Funds” of the Offer to Purchase is incorporated herein by reference.

(b) The Offer is not subject to a financing condition.

ITEM 8.

INTEREST IN SECURITIES OF THE SUBJECT COMPANY.

The information set forth in “Special Factors—Section 2. Purpose of the Offer and Plans for Theseus,” “The Tender Offer—Section 6. Certain Information Concerning Parent and Purchaser” and Schedule A—“Information Concerning Members of the Boards of Directors and the Executive Officers of Purchaser, Parent and the Guarantor” of the Offer to Purchase and Item 3—“Identity and Background of the Filing Person” hereof is incorporated herein by reference.

ITEM 9.

PERSONS/ASSETS RETAINED, EMPLOYED, COMPENSATED OR USED.

(a) The information set forth in the section of the Offer to Purchase titled “Introduction” and in “Special Factors—Section 1. Background of the Offer; Contacts with Theseus,” “The Tender Offer—Section 3. Procedures for Tendering Shares” and “The Tender Offer—Section 12. Fees and Expenses” of the Offer to Purchase is incorporated herein by reference.

ITEM 10.

FINANCIAL STATEMENTS.

Not applicable.

ITEM 11.

ADDITIONAL INFORMATION.

(a) The information set forth in “Special Factors—Section 1. Background of the Offer; Contacts with Theseus,” “Special Factors—Section 2. Purpose of the Offer and Plans for Theseus,” “Special Factors—Section 5. Possible Effects of the Offer on the Market for the Shares; Nasdaq Listing; Exchange Act Registration and Margin Regulations,” “The Tender Offer—Section 6. Certain Information Concerning Parent and Purchaser,” “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements” and “The Tender Offer—Section 11. Certain Legal Matters; Regulatory Approvals” of the Offer to Purchase is incorporated herein by reference.

ITEM 12.

EXHIBITS.

Index No.
(a)(1)(A)*			Offer to Purchase, dated January 9, 2024.
(a)(1)(B)*			Form of Letter of Transmittal.
(a)(1)(C)*			Form of Letter to Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees.
(a)(1)(D)*			Form of Letter to Clients for Use by Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees.
(a)(5)(A)			Press Release of Theseus issued on December 22, 2023 (incorporated by reference to Exhibit 99.1 to Theseus’ Current Report on Form 8-K filed with the SEC on December 22, 2023).
(d)(1)			Agreement and Plan of Merger, by and among Concentra Biosciences, LLC, Concentra Merger Sub II, Inc. and Theseus Pharmaceuticals, Inc., dated December 22, 2023 (incorporated by reference to Exhibit 2.1 to Theseus’ Current Report on Form 8-K filed with the SEC on December 22, 2023).
(d)(2)*			Confidentiality Agreement dated November 30, 2023 between Theseus, TCP and Parent.
(d)(3)			Form of Contingent Value Rights Agreement (incorporated by reference to Exhibit C of Exhibit 2.1 to Theseus’ Current Report on Form 8-K filed with the SEC on December 22, 2023).
(d)(4)*			Limited Guaranty, dated December 22, 2023.
(d)(5)			Amended and Restated Investors’ Rights Agreement, dated January 22, 2021, by and among the Registrant and the other parties thereto (incorporated by reference to Exhibit 4.2 to Theseus’ Registration Statement on Form S-1 filed with the SEC on September 15, 2021).
(d)(6)			Form of Support Agreement (incorporated herein by reference to Exhibit D of Exhibit 2.1 to Theseus’ Current Report on Form 8-K filed with the SEC on December 22, 2023).
(g)			Not applicable.
(h)			Not applicable.
107*			Filing Fee Table.

*	Filed herewith.

ITEM 13.

INFORMATION REQUIRED BY SCHEDULE 13E-3.

Not applicable.

SIGNATURE

After due inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: January 9, 2024

CONCENTRA MERGER SUB II, INC.

By:	/s/ Kevin Tang
	Name:	Kevin Tang
	Title:	Chief Executive Officer

CONCENTRA BIOSCIENCES, LLC

By:	/s/ Kevin Tang
	Name:	Kevin Tang
	Title:	Chief Executive Officer

TANG CAPITAL PARTNERS, LP

By:	/s/ Kevin Tang
	Name:	Kevin Tang
	Title:	Manager of Tang Capital Management, LLC, General Partner of Tang Capital Partners, LP

TANG CAPITAL MANAGEMENT, LLC

By:	/s/ Kevin Tang
	Name:	Kevin Tang
	Title:	Manager

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Exhibit (a)(1)(A)

Offer to Purchase

All Outstanding Shares of Common Stock

THESEUS PHARMACEUTICALS, INC.

A Cash Amount per Share between $3.90 and $4.05, Consisting of a Base Price Per Share of $3.90 and

an Additional Price Per Share of up to $0.15, Plus One Non-Transferable Contractual Contingent Value Right for Each Share (“CVR”), Which Represents the Right to Receive One or More Potential Cash Payments, Contingent upon Receipt of Proceeds from Any Disposition of CVR Products Within 180 Days of the Closing Date and the Realization of Certain Specified Potential Cost Savings

Within 180 Days of the Closing Date, as Described in the CVR Agreement

CONCENTRA MERGER SUB II, INC.

a wholly owned subsidiary of

CONCENTRA BIOSCIENCES, LLC

and

TANG CAPITAL PARTNERS, LP

and

TANG CAPITAL MANAGEMENT, LLC

THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE ONE MINUTE AFTER

11:59 P.M. EASTERN TIME ON FEBRUARY 7, 2024 (THE “EXPIRATION DATE”),

UNLESS THE OFFER IS EXTENDED OR EARLIER TERMINATED.

Concentra Merger Sub II, Inc., a Delaware corporation (“Purchaser”), and a wholly owned subsidiary of Concentra Biosciences, LLC, a Delaware limited liability company (“Parent”), is offering to purchase (the “Offer”) all outstanding shares of common stock, par value $0.0001 per share (“Shares”), of Theseus Pharmaceuticals, Inc., a Delaware corporation (“Theseus”), for (i) $3.90 per Share in cash (the “Base Price Per Share”), (ii) an additional amount of cash of up to $0.15 per Share (such amount as finally determined pursuant to the Merger Agreement (as defined below), the “Additional Price Per Share” and together with the Base Price Per Share, the “Cash Amount”), and (iii) one non-transferable contractual contingent value right for each Share (each, a “CVR,” and each CVR together with the Cash Amount, the “Offer Price”), all upon the terms and subject to the conditions described in this Offer to Purchase (together with any amendments or supplements hereto, this “Offer to Purchase”) and in the related Letter of Transmittal (together with any amendments or supplements thereto, the “Letter of Transmittal”). Accordingly, the total Cash Amount that Purchaser may pay pursuant to the terms of the Offer and Merger Agreement is between $3.90 and $4.05 per Share. Subject to the terms of the Merger Agreement (as defined below) and the CVR Agreement (as defined below), the Offer Price will be paid net of any applicable tax withholding and without interest.

The Offer is being made pursuant to the Agreement and Plan of Merger, dated as of December 22, 2023 (together with any amendments or supplements thereto, the “Merger Agreement”), among Theseus, Parent and Purchaser, pursuant to which, after the completion of the Offer and the satisfaction or waiver of certain conditions, Purchaser will be merged with and into Theseus, without a meeting or any further action of the Theseus stockholders in accordance with Section 251(h) of the General Corporation Law of the State of Delaware (the “DGCL”), and Theseus will be the surviving corporation and a wholly owned subsidiary of Parent (such corporation, the “Surviving Corporation” and such merger, the “Merger”). The time at which the Merger becomes effective is referred to as the “Effective Time” and the date upon which the Merger becomes effective is the “Closing Date.” Upon the terms and subject to the satisfaction or waiver of the conditions of the Offer

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and the Merger Agreement, including the Minimum Tender Condition (as defined below), Purchaser will accept for payment (the date and time of such acceptance, the “Offer Closing Time”) and thereafter pay for all Shares validly tendered and not validly withdrawn pursuant to the Offer promptly after the Expiration Date.

Concurrently with the execution of the Merger Agreement, and as a condition and inducement to Theseus’ willingness to enter into the Merger Agreement, Tang Capital Partners, LP, a Delaware limited partnership (“TCP”) (“Guarantor”) and sole member of Parent, delivered to Theseus a duly executed limited guaranty (the “Limited Guaranty”), dated as of the date of the Merger Agreement, in favor of Theseus, in respect of certain obligations of Parent and Purchaser under the Merger Agreement and the CVR Agreement. Certain obligations under the Limited Guaranty are subject to a cap of $177,614,912, plus certain enforcement costs, under the Merger Agreement and an amount equivalent to the CVR Proceeds (as defined below), plus certain enforcement costs, under the CVR Agreement. Tang Capital Management, LLC, a Delaware limited liability company (“TCM”), is the sole manager of Parent and the general partner of TCP. Accordingly, TCP and TCM are considered co-offerors in the Offer. As co-offerors, TCP and TCM accept joint responsibility for the accuracy of the disclosures made in this Offer to Purchase.

Pursuant to the Merger Agreement, the Additional Price Per Share, if any, will be determined based on Theseus’ good faith, estimated calculation of Closing Net Cash as of immediately prior to the Offer Closing Time (the “Cash Determination Time”). Parent and Purchaser will file with the U.S. Securities and Exchange Commission (the “SEC”) a supplement or amendment to this Offer to Purchase that includes the finally determined Additional Price Per Share no later than 9:00 a.m. Eastern Time on the first business day following the date on which the Closing Net Cash is finally determined and agreed upon by Theseus and Parent, and, pursuant to Rule 14e-1(b), the Offer will remain open for at least ten (10) business days from the date the supplement or amendment to this Offer to Purchase that includes the finally determined Additional Price Per Share is filed with the SEC. As used herein, “Closing Net Cash” means, without duplication (i) Theseus’ cash and cash equivalents and marketable securities as of the Cash Determination Time, determined in accordance with GAAP, applied on a basis consistent with Theseus’ application thereof in Theseus’ consolidated financial statements, minus (ii) the sum of Theseus’ consolidated short-term and long-term contractual obligations and liabilities (including indebtedness) accrued or incurred by or on behalf of Theseus as of the Cash Determination Time, minus (iii) all fees and expenses incurred or payable by Theseus and up to an aggregate of $300,000 in reasonable and documented fees and expenses incurred or payable by Parent or Purchaser, in each case, at or prior to the Effective Time in connection with the transactions contemplated by the Merger Agreement and the CVR Agreement, minus (iv) an estimate of all costs that the Surviving Corporation is expected to incur following the closing of the Merger (the “Estimated Costs Post-Merger Closing”), minus (v) an agreed amount of $386,705 for the expense cap under the CVR Agreement.

The total Cash Amount payable by the Purchaser pursuant to the Offer and the Merger Agreement will equal the quotient derived by dividing (A) (1) the Closing Net Cash (as finally determined pursuant to Section 2.01(d) of the Merger Agreement), plus (2) the aggregate exercise price of all In-the-Money Options (as defined below) that are outstanding as of the expiration of the Offer and entitled to receive the Company Stock Option Cash Consideration (as defined below) (the “Aggregate Exercise Price”), minus (3) $10,000,000; by (B) the total number of shares of Shares, including all shares underlying the restricted stock units granted pursuant to Theseus’ 2018 Stock Plan, Theseus’ 2021 Equity Incentive Plan, or otherwise, with each such unit representing a contingent right to receive one Share upon vesting (“Company Restricted Stock Units”), that are issued and outstanding as of immediately prior to the Offer Closing Time, and assuming the exercise of all In-the-Money Options outstanding as of the Effective Time (the “Company Outstanding Shares”). The Additional Price Per Share shall equal the Cash Amount as determined pursuant to the immediately preceding sentence, minus the Base Price Per Share.

Pursuant to the terms of the Merger Agreement, at the Effective Time, by virtue of the Merger and without any action on the part of the holders of Shares, each outstanding Share, other than Shares held in the treasury by Theseus, or by any stockholders of Theseus who are entitled to and who properly exercise appraisal rights under Delaware law, will be converted into the right to receive the Offer Price, without interest and subject to any applicable tax withholding. As of immediately prior to the Effective Time, the vesting for each option to purchase Shares from Theseus (“Company Stock Options,” and each a “Company Stock Option”) and each Company Restricted Stock Unit shall be accelerated and at the Effective Time (i)(A) each Company Stock Option that has an exercise price per share that is less than the Cash Amount (each, an “In-the-Money Option”)

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that is then outstanding will be cancelled and, in exchange therefor, the holder of such cancelled In-the-Money Option will be entitled to receive, in consideration of the cancellation of such In-the-Money Option, (1) an amount in cash, without any interest thereon and subject to applicable tax withholding, equal to the product of (x) the excess of the Cash Amount over the applicable exercise price per share under such In-the-Money Option and (y) the total number of Shares underlying such In-the-Money Option as of immediately prior to the Effective Time (the “Company Stock Option Cash Consideration”) and (2) one CVR for each Share underlying such In-the-Money Option and (B) each Company Stock Option that has a per share exercise price that is equal to or greater than the Cash Amount (each, an “Out-of-the-Money Option”) will be cancelled for no consideration; and (ii) each outstanding Company Restricted Stock Unit (each such unit having been accelerated as of immediately prior to the Offer Closing Time) shall be cancelled and the holder thereof shall be entitled to receive (A) an amount in cash without interest, less any applicable tax withholding, equal to the Cash Amount and (B) one CVR.

As noted in the Summary Term Sheet, there is a risk that: (i) you may receive no Additional Price Per Share as part of the Cash Amount; and (ii) you may receive no payments under the CVRs. Therefore, in making a decision to tender your Shares, you should understand that if the Additional Price Per Share is $0 and the CVR does not generate any payments, the only consideration that you would receive in the Offer is the Base Price Per Share that is being offered pursuant to the Offer. You should base your tender decision on the Base Price Per Share as it may be the only consideration you receive in the Offer. On January 8, 2024, the last full trading day prior to the date of this Offer to Purchase, the closing price of Theseus’ common stock as reported on Nasdaq was $4.00 per Share.

After careful consideration, the Theseus board of directors (the “Theseus Board”) have duly and unanimously: (i) determined that the terms of Offer, the Merger and the other transactions contemplated by the Merger Agreement and the CVR Agreement (collectively, the “Transactions”) are fair to and in the best interests of Theseus and the Theseus’ stockholders, (ii) approved and declared advisable the Merger and the execution, delivery and performance by Theseus of the Merger Agreement and the consummation of the Transactions, (iii) resolved that the Merger Agreement and the Merger shall be governed by and effected under Section 251(h) of the DGCL, if the conditions of Section 251(h) are satisfied, and that the Merger shall be consummated as soon as practicable following the Offer Closing Time (as defined below), and (iv) resolved to recommend that Theseus’ stockholders accept the Offer and tender their Shares pursuant to the Offer, which resolutions shall not be subsequently rescinded, modified or withdrawn in any way, except in connection with a Superior Company Proposal (as such term is used in the Merger Agreement).

The Offer is subject to various conditions. See “The Tender Offer—Section 9. Conditions of the Offer.” A summary of the principal terms of the Offer appears on pages 1 through 12 of this Offer to Purchase. You should read this entire document carefully before deciding whether to tender your Shares.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of this transaction, passed upon the merits or fairness of such transaction or passed upon the adequacy or accuracy of the information contained in this document. Any representation to the contrary is a criminal offense.

January 9, 2024

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IMPORTANT

If you desire to tender all or any portion of your Shares to us pursuant to the Offer, you should either: (i) if you hold your Shares directly as the registered owner, complete and sign the Letter of Transmittal for the Offer, which is enclosed with this Offer to Purchase, in accordance with the instructions contained in the Letter of Transmittal, mail or deliver the Letter of Transmittal and any other required documents to Broadridge Corporate Issuer Solutions, LLC (the “Depositary and Paying Agent”), and either deliver the certificates for your Shares to the Depositary and Paying Agent along with the Letter of Transmittal or tender your Shares by book-entry transfer by following the procedures described in “The Tender Offer—Section 3. Procedures for Tendering Shares” of this Offer to Purchase, in each case prior to the expiration of the Offer; or (ii) if you hold your Shares in “street name,” request that your broker, dealer, commercial bank, trust company or other nominee effect the transaction for you. If you hold Shares registered in the name of a broker, dealer, commercial bank, trust company or other nominee you must contact that institution in order to tender your Shares to us pursuant to the Offer.

* * *

Questions and requests for assistance may be directed to Morrow Sodali LLC (the “Information Agent”) at its address and telephone number set forth on the back cover of this Offer to Purchase. Requests for additional copies of this Offer to Purchase, the Letter of Transmittal and other tender offer materials may be directed to the Information Agent. You may also contact your broker, dealer, commercial bank, trust company or other nominee for assistance.

This Offer to Purchase and the Letter of Transmittal contain important information, and you should read both carefully and in their entirety before making any decision with respect to the Offer.

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		Page
SUMMARY TERM SHEET		1
INTRODUCTION		13
SPECIAL FACTORS		16
1.	BACKGROUND OF THE OFFER; CONTACTS WITH THESEUS.	16
2.	PURPOSE OF THE OFFER AND PLANS FOR THESEUS.	18
3.	REPORTS, OPINIONS, APPRAISALS AND NEGOTIATIONS.	19
4.	PRICE RANGE OF SHARES; DIVIDENDS.	19
5.	POSSIBLE EFFECTS OF THE OFFER ON THE MARKET FOR THE SHARES; NASDAQ LISTING; EXCHANGE ACT REGISTRATION AND MARGIN REGULATIONS.	19
6.	CERTAIN U.S. FEDERAL INCOME TAX CONSEQUENCES OF THE OFFER AND THE MERGER.	21
THE TENDER OFFER		27
1.	TERMS OF THE OFFER.	27
2.	ACCEPTANCE FOR PAYMENT AND PAYMENT FOR SHARES.	29
3.	PROCEDURES FOR TENDERING SHARES.	29
4.	WITHDRAWAL RIGHTS.	32
5.	CERTAIN INFORMATION CONCERNING THESEUS.	32
6.	CERTAIN INFORMATION CONCERNING PARENT AND PURCHASER.	33
7.	SUMMARY OF THE MERGER AGREEMENT AND CERTAIN OTHER AGREEMENTS.	34
8.	SOURCE AND AMOUNT OF FUNDS.	46
9.	CONDITIONS OF THE OFFER.	47
10.	DIVIDENDS AND DISTRIBUTIONS.	48
11.	CERTAIN LEGAL MATTERS; REGULATORY APPROVALS.	48
12.	FEES AND EXPENSES.	52
13.	MISCELLANEOUS.	52

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SUMMARY TERM SHEET

The following are some questions you, as a stockholder of Theseus, may have, and answers to those questions. This Summary Term Sheet highlights selected information from this Offer to Purchase, and may not contain all of the information that is important to you and is qualified in its entirety by the more detailed descriptions and explanations contained in the Merger Agreement, the contingent value rights agreement, which is in substantially the form attached as Exhibit C to the Merger Agreement (the “CVR Agreement”), the Limited Guaranty, this Offer to Purchase and the related Letter of Transmittal. To better understand the Offer and for a complete description of the legal terms of the Offer, you should read the Merger Agreement, the CVR Agreement, the Limited Guaranty, this Offer to Purchase and the related Letter of Transmittal carefully and in their entirety. Questions or requests for assistance may be directed to Morrow Sodali LLC (the “Information Agent”) at its address and telephone number, as set forth on the back cover of this Offer to Purchase. Unless otherwise indicated in this Offer to Purchase or the context otherwise requires, all references in this Offer to Purchase to “we,” “our,” or “us” refer to Purchaser, Parent, Guarantor or TCP as the context requires.

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WHO IS OFFERING TO BUY MY SECURITIES?

•

Purchaser, a wholly owned subsidiary of Parent, is offering to buy your securities. Purchaser has been organized in connection with this Offer and has not carried on any activities other than entering into the Merger Agreement and activities in connection with the Offer. See “The Tender Offer—Section 6. Certain Information Concerning Parent and Purchaser.” Certain obligations of Parent and Purchaser under the Merger Agreement have been guaranteed by TCP, pursuant to the Limited Guaranty.

•	Parent is Concentra Biosciences, LLC. See “The Tender Offer—Section 6. Certain Information Concerning Parent and Purchaser.”

•	Purchaser is Concentra Merger Sub II, Inc. See “The Tender Offer—Section 6. Certain Information Concerning Parent and Purchaser.”

•	Guarantor is Tang Capital Partners, LP. See “The Tender Offer—Section 6. Certain Information Concerning Parent and Purchaser.”

•	The sole manager of Parent and the general partner of Guarantor is Tang Capital Management, LLC. See “The Tender Offer—Section 6. Certain Information Concerning Parent and Purchaser.”

WHAT ARE THE CLASSES AND AMOUNTS OF SECURITIES SOUGHT IN THE OFFER?

•	Purchaser is seeking to purchase all of the outstanding Shares of Theseus. See the Introduction and “The Tender Offer—Section 1. Terms of the Offer.”

HOW MUCH IS PURCHASER OFFERING TO PAY AND WHAT IS THE FORM OF PAYMENT?

•

Purchaser is offering to pay a cash amount per share of between $3.90 and $4.05, consisting of a Base Price Per Share of $3.90 and an Additional Price Per Share of up to $0.15 (the Base Price Per Share and the Additional Price Per Share are together referred to as the “Cash Amount”), plus one non-transferable CVR for each Share, which represents the right to receive potential cash payments, contingent upon receipt of proceeds from any disposition of CVR Products within 180 days of the Closing Date and certain specified potential cost savings that are realized within 180 days of the Closing Date, as described in the CVR Agreement, in each case, without interest and subject to any applicable tax withholding, upon the terms and subject to the conditions contained in this Offer to Purchase and in the related Letter of Transmittal. There is a risk that: (i) you may receive no payments for the Additional Price Per Share as part of the Cash Amount; and (ii) you may receive no payments under the CVRs. Therefore, in making a decision to tender your Shares, you should understand that if the Additional Price Per Share is $0 and the CVR does not generate any payments, the only consideration that you would receive in the Offer is the Base Price Per Share of $3.90 that is being offered pursuant to the Offer. You should base your tender decision on the Base Price Per Share of $3.90 as it may be the only consideration you receive in the Offer. See the Introduction and “The Tender Offer—Section 1. Terms of the Offer.”

•

The Additional Price Per Share will be determined based on Theseus’ good faith, estimated calculation of Closing Net Cash as of immediately prior to the Offer Closing Time (the “Cash Determination Time”). As used herein, “Closing Net Cash” means, without duplication (i) Theseus’ cash and cash equivalents and marketable securities as of the Cash Determination Time, determined in accordance with GAAP, applied on a basis consistent with Theseus’ application thereof in Theseus’ consolidated financial statements, minus (ii) the sum of Theseus’ consolidated short-term and long-term contractual obligations and liabilities (including indebtedness) accrued or incurred by or on behalf of Theseus as of the Cash Determination Time, minus (iii) all fees and expenses incurred or payable by Theseus and up to an aggregate of $300,000 in reasonable and documented fees and expenses incurred or payable by Parent or Purchaser, in each case, at or prior to the Effective Time in connection with the transactions contemplated by the Merger Agreement and the CVR Agreement, minus (iv) an estimate of all costs that the Surviving Corporation would incur post-Merger closing (the “Estimated Costs Post-Merger Closing”), minus (v) an agreed amount of $386,705 for the expense cap under the CVR Agreement.

•	The total Cash Amount payable by the Purchaser pursuant to the Offer and the Merger Agreement will equal the quotient derived by dividing (A) (1) the Closing Net Cash (as finally determined pursuant to

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Section 2.01(d) of the Merger Agreement), plus (2) the aggregate exercise price of all In-the-Money Options (as defined below) that are outstanding as of the expiration of the Offer and entitled to receive the Company Stock Option Cash Consideration (as defined below) (the “Aggregate Exercise Price”), minus (3) $10,000,000; by (B) the total number of shares of Shares, including all shares underlying the restricted stock units granted pursuant to Theseus’ 2018 Stock Plan, Theseus’ 2021 Equity Incentive Plan, or otherwise, with each such unit representing a contingent right to receive one Share upon vesting (“Company Restricted Stock Units”), that are issued and outstanding as of immediately prior to the Offer Closing Time, and assuming the exercise of all In-the-Money Options outstanding as of the Effective Time (the “Company Outstanding Shares”). The Additional Price Per Share shall equal the Cash Amount as determined pursuant to the immediately preceding sentence, minus the Base Price Per Share. See the Introduction and “The Tender Offer—Section 1. Terms of the Offer.”

You will only receive payments for any Additional Price Per Share if the Cash Amount is greater than the Base Price Per Share. In making a decision to tender your Shares in the Offer, you should understand that there can be no assurance that any Additional Price Per Share will be payable, and therefore, it is possible that the Cash Amount may be equal to, and no greater than, the Base Price Per Share.

WILL I HAVE TO PAY ANY FEES OR COMMISSIONS?

•

If your Shares are registered in your name and you tender your Shares, you will not be obligated to pay brokerage fees or commissions or similar expenses. If you hold your Shares through a broker, dealer, commercial bank, trust company or other nominee and your broker, dealer, commercial bank, trust company or other nominee tenders your Shares on your behalf, your broker, dealer, commercial bank, trust company or other nominee may charge a fee for doing so. You should consult your broker, dealer, commercial bank, trust company or other nominee to determine whether any charges will apply. See the Introduction and “The Tender Offer—Section 3. Procedures for Tendering Shares.”

WHAT IS THE CVR AND HOW DOES IT WORK?

•

At or prior to the Offer Closing Time, Parent, Purchaser, the rights agent (the “Rights Agent”) and the representative of the holders of the CVRs (the “Representative”) will enter into the CVR Agreement, governing the terms of the CVRs. Each CVR will represent a contractual right to receive contingent cash payments equal to a pro rata share of: (i) 80% of the Net Proceeds (as defined in the CVR Agreement), if any, from any sale, transfer, license or other disposition (each, a “Disposition”) by Parent or any of its affiliates, including Theseus (after the Merger), of all or any part of (a) Theseus’ product candidate known as THE-349, a fourth-generation epidermal growth factor receptor, or EGFR, inhibitor for the treatment of non-small cell lung cancer, (b) Theseus’ next-generation BCR-ABL program focused on relapsed/refractory chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia, or (c) Theseus’ KIT inhibitor program for the treatment of gastrointestinal stromal tumors (collectively, the “CVR Products” and such payment the “Disposition Proceeds”) which Disposition occurs within 180 days of the Closing Date (such period, the “Disposition Period”); and (ii) 50% of any net savings versus the Closing Net Cash that is realized between the date of the Closing Date and the end of the Disposition Period (such payment the “Further Savings Proceeds” and collectively with the Disposition Proceeds, the “CVR Proceeds”).

•

Any Disposition Proceeds would be calculated and payable based on a distribution of Net Proceeds from Dispositions and we cannot predict whether any Dispositions will occur at all, or at what price they may be effected. Net Proceeds would depend upon various unknown factors, including market conditions, the identification of potential acquirers, the conclusions reached by potential acquirers after conducting due diligence with respect to the assets and Parent and Purchaser’s ability to negotiate and consummate Dispositions with such third parties. Any Further Savings Proceeds would be calculated and payable based on any net savings versus the Closing Net Cash and we cannot predict whether any such savings will be realized at all, or to what extent. Net savings would depend upon various unknown factors, including unforeseen costs that the Surviving Corporation would incur post-Closing Date.

In connection with the Offer, none of the co-offerors engaged any independent valuation firm to conduct an analysis of the potential value of the CVR Products or received any material non-public information

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assessing the value of the CVR Products. Accordingly, in making a decision to tender your Shares in the Offer, you should understand that there can be no assurance that we will be able to: (i) consummate any Dispositions during the Disposition Period or that such Dispositions, if any, will generate Net Proceeds; or (ii) realize any net savings versus the Closing Net Cash to generate any Further Savings Proceeds. You should also understand that, as discussed below, the co-offerors estimate that the amount that will be payable under the CVRs is most likely $0.00 per CVR.

•

During the Disposition Period, Parent has agreed to undertake certain specified actions, which the parties have agreed will constitute commercially reasonable efforts, in furtherance of the entry into one or more agreements providing for a Disposition (each a “Disposition Agreement”) and effectuate the completion of the transactions contemplated thereby as promptly as practicable after the Effective Time, subject to certain limitations set forth in the CVR Agreement. Parent and its subsidiaries are not required or obligated to incur costs, fees or expenses in excess of $386,705 (the “Expense Cap”) in performing such actions under the CVR Agreement with respect to: (i) Disposition business development efforts related to the CVR Products, (ii) the retention of an employee or consultant of Parent or Purchaser for the purpose of maintaining and preserving the CVR Products and seeking, negotiating and executing Disposition Agreements, (iii) the maintenance of the CVRs, and (iv) the maintenance and prosecution of the intellectual property relating to CVR Products. Purchaser has also agreed that only during the Disposition Period, Purchaser and its subsidiaries, licensees and rights transferees will use commercially reasonable efforts to manage the inventory related to raw materials, starting materials, intermediate materials, drug substance or drug product related to the CVR Products, including the maintenance of ongoing stability studies and the extension of shelf life accordingly of any CVR Product in accordance with Parent’s plans as of the Closing Date. Commercially reasonable efforts shall not include, among other actions, pursuing new clinical, manufacturing or enabling work with respect to the CVR Products.

•

Parent’s and the Guarantor’s financial condition could deteriorate such that they would not have the necessary cash or cash equivalents to make the required payments pursuant to the CVR Agreement. The CVR holders will have no greater rights against Parent under the CVR Agreement, or the Guarantor under the Limited Guaranty, than those of general unsecured creditors of Parent or the Guarantor, as applicable, including in the event of any bankruptcy. The CVRs would be effectively junior in right of payment to all of Parent’s and the Guarantor’s secured obligations to the extent of the collateral securing such obligations, and the CVRs would be pari passu with all of Parent’s and the Guarantor’s unsecured obligations, including trade payables, pursuant to the CVR Agreement and the Limited Guaranty, as applicable. The Guarantor’s obligation with respect to the CVRs under the Limited Guaranty is subject to a cap of an amount equivalent to the CVR Proceeds, plus certain enforcement costs, under the CVR Agreement.

•

It is currently anticipated that up to an aggregate of 47,697,016 CVRs will be issued assuming the maximum potential Cash Amount of $4.05 per Share, representing CVRs to be issued as part of the consideration for each of the issued and outstanding Shares, as well as Shares underlying each outstanding In-the-Money Option and Company Restricted Stock Units immediately prior to the Effective Time. For more information regarding the CVR Agreement, see “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements.”

IS IT POSSIBLE THAT NO PAYMENTS WILL BE PAYABLE TO THE HOLDERS OF CONTINGENT VALUE RIGHTS IN RESPECT OF SUCH CONTINGENT VALUE RIGHTS?

•

Yes. You will only receive payments with respect to your CVRs if (i) a Disposition Agreement entered into during the Disposition Period results in Net Proceeds and/or (ii) any net savings versus the Closing Net Cash are realized between the Closing Date and the end of the Disposition Period. If none of the events described in clauses (i) or (ii) above occur, you will receive only the Cash Amount for your Shares and no payments with respect to your CVRs.

•	The co-offerors estimate that the amount that will be payable under the CVRs is most likely $0.00 per CVR, consisting of $0.00 per CVR in Disposition Proceeds and $0.00 per CVR in Further Savings Proceeds.

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•

The co-offerors’ estimate of the Disposition Proceeds is based on the co-offerors’ assessment of the CVR Products together with Theseus’ independent estimate. Theseus previously conducted an extensive business development process in an effort to out-license the CVR Products and concluded that the market opportunity for the CVR Products is limited. Even if market conditions were to change, there would still be significant uncertainty regarding co-offerors’ ability to attract a potential acquirer for the CVR Products and, even if co-offerors were to be successful in negotiating transaction terms with a potential acquirer of the CVR Products, whether any potential acquirer of the CVR Products would be able to (i) initiate and complete successful nonclinical studies and clinical trials for any product related to or based upon the CVR Products, (ii) conduct sufficient clinical trials or other studies to support the approval and commercialization of any product related to the CVR Products, (iii) demonstrate to the satisfaction of the U.S. Food and Drug Administration and similar foreign regulatory authorities the safety and efficacy and acceptable risk-to-benefit profile of any product related to the CVR Products, (iv) seek and obtain regulatory marketing approvals for any product related to the CVR Products, (v) establish and maintain supply and manufacturing relationships with third parties to ensure adequate and legally compliant manufacturing of bulk drug substances and drug products to maintain that supply, (vi) launch and commercialize any product candidates that were to obtain marketing approval and, if launched, successfully establish a sales, marketing and distribution infrastructure, (vii) demonstrate the necessary safety data post-approval to ensure continued regulatory approval, (viii) demonstrate the actual and perceived benefits of any product related to the CVR Products, if approved, relative to existing and future alternative therapies based upon availability, cost, risk and safety profile, drug-drug interactions, ease of administration, side effects and efficacy, (ix) obtain coverage and adequate product reimbursement from third-party payors, including government payors, (x) achieve market acceptance for any approved products, (xi) address any competing technological and market developments, (xii) negotiate favorable terms in any collaboration, licensing or other arrangements into which such acquirer may enter in the future and perform its obligations under such collaborations, (xiii) establish, maintain, protect and enforce intellectual property rights related to the CVR Products and (xiv) attract, hire and retain qualified personnel, among other unknowns.

•

The co-offerors estimate that the amount that will be payable under the CVRs with respect to the Further Savings Proceeds is most likely $0.00 per CVR. By way of example, if Theseus’ Estimated Costs Post-Merger Closing were approximately $1.0 million, and none of such costs were incurred by the Surviving Corporation, the net savings would be $1.0 million, or approximately $0.01 per CVR. Conversely, if all or more of these costs were incurred by the Surviving Corporation, the net savings would be $0, or $0.00 per CVR.

•	In considering whether to tender your Shares in the Offer, you should consider that it is entirely possible that no cash will be distributed to the holders of the CVR under the terms of the CVR Agreement.

For more information regarding the CVR Agreement, see “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements.”

MAY I TRANSFER MY CONTINGENT VALUE RIGHTS?

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The CVRs will not be transferable except: (i) upon death of the holder by will or intestacy; (ii) pursuant to a court order; (iii) by operation of law (including a consolidation or merger) or without consideration in connection with the dissolution, liquidation or termination of any corporation, limited liability company, partnership or other entity; (iv) in the case of CVRs held in book-entry or other similar nominee form, from a nominee to a beneficial owner and, if applicable, through an intermediary, to the extent allowable by the Depository Trust Company (“DTC”); or (v) that CVRs may be abandoned, as provided under Section 2.7 of the CVR Agreement. For more information regarding the CVR Agreement, see “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements.”

ARE THERE OTHER MATERIAL TERMS OF THE CONTINGENT VALUE RIGHTS?

•	In addition to the terms and conditions described above, the CVRs will not have any voting or dividend rights and will not represent any equity or ownership in Parent, any constituent corporation party to the

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Merger or any of its affiliates. No interest will accrue or become payable in respect of any of the amounts that may become payable on the CVRs. For more information regarding the CVR Agreement, see “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements.”

WHY IS PURCHASER MAKING THE OFFER?

•	Parent, through Purchaser, has undertaken to acquire control of, and the entire equity interest in, Theseus because it believes it is a good investment. See “Special Factors—Section 2. Purpose of the Offer and Plans for Theseus” and “The Tender Offer—Section 1. Terms of the Offer.”

WHAT ARE THE MOST SIGNIFICANT CONDITIONS OF THE OFFER?

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Pursuant to the Merger Agreement, Purchaser’s obligation to accept Shares tendered in the Offer is subject to the satisfaction or waiver of certain conditions. Purchaser will not be required to, and Parent shall not be required to cause Purchaser to, accept for payment or, subject to any applicable rules and regulations of the SEC, including Rule 14e-1(c) under the Exchange Act (relating to Purchaser’s obligation to pay for or return tendered Shares promptly after the termination or withdrawal of the Offer), pay for any Shares tendered pursuant to the Offer and, subject to the terms of the Merger Agreement, may delay the acceptance for payment of or payment for Shares or may terminate or amend the Offer, if:

(a)	prior to the Expiration Date, there shall not have been validly tendered (and not properly withdrawn) at least one Share more than 50% of the number of Shares that are then issued and outstanding as of the expiration of the Offer (the “Minimum Tender Condition”); or

(b)	any of the following conditions exist or shall have occurred and be continuing at the Expiration Date:

(i)	there shall be any Legal Restraint (as defined in the Merger Agreement) in effect preventing or prohibiting the consummation of the Offer, the Merger or any of the other transactions contemplated by the Merger Agreement or CVR Agreement;

(ii)

(A) (1) any representation or warranty of Theseus set forth in Article IV of the Merger Agreement (other than those set forth in Section 4.01 (Organization, Standing and Power) (but only with respect to the first and second sentences thereof), Section 4.02 (Capital Structure), Section 4.04 (Authority; Execution and Delivery; Enforceability), Section 4.05(a)(i) (No Conflicts), Section 4.08(a) (No Material Adverse Effect), Section 4.20 (Brokers and Other Advisors), Section 4.22 (Opinion of Financial Advisors) and Section 4.23 (No Vote Required)) shall not be true and correct as of the Agreement Date and at and as of the Offer Closing Time as if made on and as of the Offer Closing Time, except to the extent such representation or warranty expressly relates to a specified date (in which case on and as of such specified date), other than for such failures to be true and correct that have not had or would not reasonably be expected to have, individually or in the aggregate, a Company Material Adverse Effect (as defined in the Merger Agreement) (for purposes of determining the satisfaction of this condition, without regard to any qualifications or exceptions contained therein as to “materiality” or “Company Material Adverse Effect”), (2) any representation or warranty of Theseus set forth in Section 4.01 (Organization, Standing and Power) (but only with respect to the first and second sentences thereof), Section 4.02(b), (f) and (g) (Capital Structure), Section 4.04 (Authority; Execution and Delivery; Enforceability), Section 4.05(a)(i) (No Conflicts), Section 4.20 (Brokers and other Advisors), Section 4.22 (Opinion of Financial Advisors), Section 4.23 (No Vote Required), and the Closing Cash Schedule shall not be true and correct in all material respects as of the Agreement Date and at and as of the Offer Closing Time as if made on and as of the Offer Closing Time, except to the extent such representation or warranty expressly relates to a specified date (in which case on and as of such specified date), (3) any representation or warranty of Theseus set forth in Section 4.02(a), (c), (d) and (e) (Capital Structure) of the Merger Agreement shall not be true and correct other than in de minimis respects at and as of such time, except to the extent such

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representation or warranty expressly relates to a specified date (in which case on and as of such specified date) and (4) any representation or warranty of Theseus set forth in Section 4.08(a) (No Material Adverse Effect) of the Merger Agreement shall not be true and correct in all respects as of such time;

(B) Theseus shall have failed to perform in all material respects the obligations to be performed by it as of such time under the Merger Agreement, including without limitation Theseus’ obligations under Section 6.02 of the Merger Agreement;

(C) Parent shall have failed to receive from Theseus a certificate, dated as of the date on which the Offer expires and signed by an executive officer of Theseus, certifying to the effect that the Offer Conditions set forth in clauses (A) and (B) have been satisfied as of immediately prior to the expiration of the Offer;

(iii)

the Merger Agreement shall have been validly terminated in accordance with its terms (the “Termination Condition”); or

(iv)	the Closing Net Cash as finally determined pursuant to Section 2.01(d) of the Merger Agreement is less than $187,614,912 (the “Minimum Cash Condition”).

Purchaser and Parent reserve the right to waive certain of the conditions to the Offer in their sole discretion (including the Minimum Cash Condition to the Offer described in the foregoing clause (iv) above); provided that they may not waive the Minimum Tender Condition or the Termination Condition. The Minimum Cash Condition is subject to Closing Net Cash equal to or greater than $187,614,912, which results in a Cash Amount equal to the Base Price Per Share of $3.90. If the Closing Net Cash is $187,614,912, the Additional Price Per Share would be equal to $0.00.

A more detailed discussion of the conditions to consummation of the Offer is contained in the Introduction, “The Tender Offer—Section 1. Terms of the Offer” and “The Tender Offer—Section 9. Conditions of the Offer.”

IS THERE AN AGREEMENT GOVERNING THE OFFER?

•

Yes. Theseus, Parent and Purchaser have entered into the Merger Agreement. The Merger Agreement provides, among other things, for the terms and conditions of the Offer and, following consummation of the Offer, the Merger. See “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements.” Additionally, the obligations of Parent and Purchaser under the Merger Agreement have been guaranteed by the Guarantor pursuant to the Limited Guaranty, subject to the terms and conditions set forth therein.

DOES PARENT HAVE FINANCIAL RESOURCES TO MAKE PAYMENTS IN THE OFFER AND, IF REQUIRED, IN RESPECT OF THE CVRS?

•

Yes. Purchaser expects to (i) pay cash consideration for all Shares accepted for payment in the Offer with some or all of Theseus’ Closing Net Cash as finally determined pursuant to the Merger Agreement, and (ii) make any payments of CVR Proceeds with the Net Proceeds from the applicable Disposition of CVR Products, if any, and/or with net savings versus the Closing Net Cash that are realized between the Closing Date and the end of the Disposition Period, if any. In connection with the execution of the Merger Agreement, the Guarantor agreed to guarantee certain of Parent’s and Purchaser’s obligations under the Merger Agreement and certain of Parent’s obligations under the CVR Agreement, subject to the terms and conditions set forth in the Limited Guaranty. The Guarantor’s obligations under the Limited Guaranty are subject to a cap of $177,614,912, plus certain enforcement costs, under the Merger Agreement and an amount equivalent to the CVR Proceeds, plus certain enforcement costs, under the CVR Agreement. See “Special Factors—Section 2. Purpose of the Offer and Plans for Theseus,” “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements” and “The Tender Offer—Section 8. Source and Amount of Funds.”

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SHOULD PURCHASER’S FINANCIAL CONDITION BE RELEVANT TO MY DECISION TO TENDER IN THE OFFER?

•

No, we do not believe it is relevant for the reasons set forth herein. The funds to pay for all Shares accepted for payment in the Offer may be funded entirely by Theseus’ Closing Net Cash as finally determined pursuant to the Merger Agreement. Any payments of CVR Proceeds will be paid from the Net Proceeds from the applicable Disposition of CVR Products, if any, and/or from net savings versus the Closing Net Cash that are realized between the Closing Date and the end of the Disposition Period, if any. In addition, in connection with the execution of the Merger Agreement, the Guarantor agreed to guarantee certain of Parent’s and Purchaser’s obligations under the Merger Agreement and certain of Parent’s obligations under the CVR Agreement, subject to the terms and conditions set forth in the Limited Guaranty. The Guarantor’s obligations under the Limited Guaranty are subject to a cap of $177,614,912, plus certain enforcement costs, under the Merger Agreement and an amount equivalent to the CVR Proceeds, plus certain enforcement costs, under the CVR Agreement.

•

Purchaser has been organized solely in connection with the Merger Agreement and this Offer and has not carried on any activities other than in connection with the Merger Agreement and this Offer. Purchaser’s financial condition is not relevant to your decision to tender in the Offer because: (i) the form of payment consists solely of cash (which may be supported entirely by Theseus’ Closing Net Cash as finally determined in accordance with the Merger Agreement and the Limited Guaranty) and CVRs (which will be supported by the Net Proceeds from the applicable Disposition(s) of CVR Products, if any, and/or from net savings versus the Closing Net Cash that are realized between the Closing Date and the end of the Disposition Period, if any), (ii) the Offer is not subject to any financing conditions, (iii) the Offer is for all outstanding Shares of Theseus, and (iv) the Purchaser does not have any relevant historical information. See “The Tender Offer—Section 8. Source and Amount of Funds.”

HOW LONG DO I HAVE TO DECIDE WHETHER TO TENDER IN THE OFFER?

•	You will have until one minute after 11:59 p.m. Eastern Time on February 7, 2024, to tender your Shares in the Offer, unless Purchaser extends the Offer, in which event you will have until the Expiration Date of the Offer as so extended. See also “The Tender Offer—Section 1. Terms of the Offer.”

CAN THE OFFER BE FURTHER EXTENDED, AND UNDER WHAT CIRCUMSTANCES?

•

Yes, the Offer can be extended. We have agreed in the Merger Agreement, subject to our rights to terminate the Merger Agreement in accordance with its terms, if on any then-scheduled expiration of the Offer the Minimum Tender Condition has not been satisfied or any Offer Condition (as defined in the Merger Agreement) has not been satisfied or waived by Purchaser (set forth in “The Tender Offer—Section 9. Conditions of the Offer”), Purchaser may, in its discretion, or at the request of Theseus, Purchaser shall, extend the Offer (i) for periods of up to 10 business days per extension to permit such Offer Condition to be satisfied or (ii) for any period required by any rule, regulation, interpretation or position of the SEC or the staff thereof or the rules of The Nasdaq Stock Market LLC (“Nasdaq”) applicable to the Offer; provided, that, in no event shall Parent or Purchaser be permitted or required to extend the Offer beyond April 21, 2024 (the “Outside Date”).

HOW WILL I BE NOTIFIED IF THE OFFER IS FURTHER EXTENDED?

•

If Purchaser further extends the Offer, we will inform Broadridge Corporate Issuer Solutions, LLC, the depositary and paying agent for this Offer (the “Depositary and Paying Agent”), of that fact and will file with the SEC and disseminate to the holders of Shares, as and to the extent required by law, a supplement or amendment to this Offer to Purchase giving the new Expiration Date no later than 9:00 a.m. Eastern Time on the next business day after the day on which the Offer was previously scheduled to expire. See “The Tender Offer—Section 1. Terms of the Offer.”

HOW DO I TENDER MY SHARES?

•	If you hold your Shares directly as the registered owner, you can: (i) tender your Shares in the Offer by delivering the certificates representing your Shares, together with a completed Letter of Transmittal and

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any other documents required by the Letter of Transmittal, to the Depositary and Paying Agent; or (ii) tender your Shares by following the procedure for book-entry set forth in “The Tender Offer—Section 3. Procedures for Tendering Shares,” not later than the expiration of the Offer. See “The Tender Offer—Section 3. Procedures for Tendering Shares.” The Letter of Transmittal is enclosed with this Offer to Purchase.

•

If you hold your Shares in street name (i.e., through a broker, dealer, commercial bank, trust company or other nominee), you must contact the institution that holds your Shares and give instructions that your Shares be tendered. You should contact the institution that holds your Shares for more details.

•

In all cases, payment for tendered Shares will be made only after timely receipt by the Depositary and Paying Agent of certificates for such Shares (or of a confirmation of a book-entry transfer of such Shares as described in “The Tender Offer—Section 3. Procedures for Tendering Shares”) and a properly completed and duly executed Letter of Transmittal and any other required documents for such Shares. See also “The Tender Offer—Section 2. Acceptance for Payment and Payment for Shares.”

UNTIL WHAT TIME CAN I WITHDRAW PREVIOUSLY TENDERED SHARES?

•	You may withdraw previously tendered Shares any time prior to one minute after 11:59 p.m. Eastern Time on February 7, 2024, unless Purchaser extends the Offer. See “The Tender Offer—Section 4. Withdrawal Rights.”

•

In addition, pursuant to Section 14(d)(5) of the Securities Exchange Act of 1934, as amended, Shares may be withdrawn at any time after March 9, 2024, which is the 60th day after the date of the commencement of the Offer, unless such Shares have already been accepted for payment by Purchaser pursuant to the Offer.

HOW DO I WITHDRAW PREVIOUSLY TENDERED SHARES?

•

To withdraw previously tendered Shares, you must deliver a written or facsimile notice of withdrawal with the required information to the Depositary and Paying Agent while you still have the right to withdraw. If you tendered Shares by giving instructions to a broker, dealer, commercial bank, trust company or other nominee, you must instruct the broker, dealer, commercial bank, trust company or other nominee to arrange for the withdrawal of your Shares. See “The Tender Offer—Section 4. Withdrawal Rights.”

WHAT DOES THESEUS’ BOARD OF DIRECTORS THINK OF THE OFFER?

•

After careful consideration and upon the unanimous recommendation of the Theseus’ board of directors (the “Theseus Board”), the members of the Theseus Board have unanimously recommended that you accept the Offer. Theseus’ full statement on the Offer is set forth in its Solicitation/Recommendation Statement on Schedule 14D-9, which it has filed with the SEC on the date hereof. See also the “Introduction” below.

WILL THE TENDER OFFER BE FOLLOWED BY A MERGER IF ALL THE SHARES ARE NOT TENDERED?

•

If we accept Shares for payment pursuant to the Offer, then the Minimum Tender Condition will have been satisfied and we will hold a sufficient number of Shares to effect the Merger without a vote by Theseus stockholders under the General Corporation Law of the State of Delaware (the “DGCL”). If the Merger occurs, then Theseus will become a wholly owned subsidiary of Parent and each issued and then outstanding Share, other than Shares held in the treasury by Theseus, or by any stockholders of Theseus who are entitled to and who properly exercise appraisal rights under Delaware law, will be converted into the right to receive the Offer Price, without interest and subject to any applicable tax withholding. For more information, see the “Introduction” below.

•	Because the Merger will be governed by Section 251(h) of the DGCL, no stockholder vote will be required to consummate the Merger. As required by Section 251(h) of the DGCL, the Merger Agreement provides that the Merger shall be effected as soon as practicable following the time

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Purchaser first irrevocably accepts for purchase the Shares tendered in the Offer (the “Offer Closing Time”). See “Special Factors—Section 2. Purpose of the Offer and Plans for Theseus” and “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements.”

IF THE OFFER IS COMPLETED, WILL THESEUS CONTINUE AS A PUBLIC COMPANY?

•

No. Immediately following the Offer Closing Time and satisfaction or waiver (to the extent permitted by applicable law) of the conditions to the Merger, we expect to complete the Merger pursuant to applicable provisions of the DGCL, after which the Surviving Corporation will be a wholly owned subsidiary of Parent, and the Shares will be delisted from Nasdaq, and Theseus’ obligations to file periodic reports under the Exchange Act will be suspended, and Theseus will be privately held. See “Special Factors—Section 5. Possible Effects of the Offer on the Market for the Shares; Nasdaq Listing; Exchange Act Registration and Margin Regulations.”

IF I DECIDE NOT TO TENDER, HOW WILL THE OFFER AFFECT MY SHARES?

•	If you decide not to tender your Shares in the Offer and the Merger occurs as described above, you will receive in the Merger the right to receive the Offer Price as if you had tendered your Shares in the Offer.

•

If you decide not to tender your Shares in the Offer and the Merger does not occur, you will remain a stockholder of Theseus. Subject to limited conditions, if we purchase Shares in the Offer, we are obligated under the Merger Agreement to cause the Merger to occur. See “Special Factors—Section 5. Possible Effects of the Offer on the Market for the Shares; Nasdaq Listing; Exchange Act Registration and Margin Regulations.”

•

Following the Offer Closing Time, the Shares may no longer constitute “margin securities” for purposes of the margin regulations of the Federal Reserve Board, in which case your Shares may no longer be used as collateral for loans made by brokers. See “Special Factors—Section 5. Possible Effects of the Offer on the Market for the Shares; Nasdaq Listing; Exchange Act Registration and Margin Regulations.”

WHAT IS THE MARKET VALUE OF MY SHARES AS OF A RECENT DATE?

•	On January 8, 2024, the last full trading day prior to the date of this Offer to Purchase, the last reported closing price per Share reported on Nasdaq was $4.00. See “Special Factors—Section 4. Price Range of Shares; Dividends.”

IF I ACCEPT THE OFFER, WHEN AND HOW WILL I GET PAID?

•

If the conditions to the Offer as set forth in the Introduction and “The Tender Offer—Section 9. Conditions of the Offer” are satisfied or waived and Purchaser consummates the Offer and accepts your Shares for payment, we will pay you a dollar amount in cash equal to the number of Shares you tendered multiplied by the Cash Amount, plus one CVR for each Share, in each case, without interest and subject to any applicable tax withholding, promptly following the time at which Purchaser accepts for payment Shares tendered in the Offer (and in any event within three business days). See “The Tender Offer—Section 1. Terms of the Offer” and “The Tender Offer—Section 2. Acceptance for Payment and Payment for Shares.”

•

We will pay to the holders of CVRs the applicable CVR Proceeds, if any, within 30 days following the receipt of Gross Proceeds (as defined in the CVR Agreement) by Parent pursuant to which Disposition Proceeds are payable and within 210 days following the Closing Date pursuant to which Further Savings Proceeds are payable.

•	For more information regarding the CVR Agreement, see “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements.”

IF I AM AN EMPLOYEE OF THESEUS, HOW WILL MY OUTSTANDING EQUITY AWARDS BE TREATED IN THE OFFER AND THE MERGER?

•	As of immediately prior to the Effective Time, the vesting for each outstanding and unvested Company Stock Option and Company Restricted Stock Unit shall be accelerated and at the Effective Time

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(i)(A) each Company Stock Option that has an exercise price per share that is less than the Cash Amount (each, an “In-the-Money Option”) that is then outstanding will be cancelled and, in exchange therefor, the holder of such cancelled In-the-Money Option will be entitled to receive, in consideration of the cancellation of such In-the-Money Option, (1) an amount in cash, without any interest thereon and subject to applicable tax withholding, equal to the product of (x) the excess of the Cash Amount over the applicable exercise price per share under such In-the-Money Option and (y) the total number of Shares underlying such In-the-Money Option as of immediately prior to the Effective Time (the “Company Stock Option Cash Consideration”) and (2) one CVR for each Share subject thereto and (B) each Company Stock Option that has a per share exercise price that is equal to or greater than the Cash Amount (each, an “Out-of-the-Money Option”) will be cancelled for no consideration; and (ii) each outstanding Company Restricted Stock Unit shall be cancelled and the holder thereof shall be entitled to receive (A) an amount in cash without interest, less any applicable tax withholding, equal to the Cash Amount and (B) one CVR.

WHAT ARE THE PRINCIPAL U.S. FEDERAL INCOME TAX CONSEQUENCES OF TENDERING MY SHARES IN THE OFFER OR HAVING MY SHARES EXCHANGED FOR THE OFFER PRICE PURSUANT TO THE MERGER?

•

The receipt of cash and CVRs in exchange for Shares pursuant to the Offer or the Merger will be treated for U.S. federal income tax purposes either as (1) consideration received in a sale or exchange of the Shares that you exchange in the Offer or the Merger or (2) a distribution in respect of your Shares. The amount of income, gain or loss a holder recognizes, and the timing and character of such income, gain or loss will depend on the U.S. federal income tax treatment of the CVRs, with respect to which there is uncertainty. To the extent required to take a position, we intend to act consistently with the receipt of the CVRs as part of a “closed transaction” for U.S. federal income tax purposes. Assuming such treatment is respected by the Internal Revenue Service (“IRS”), a U.S. Holder (as defined below in “Special Factors—Section 7. Certain U.S. Federal Income Tax Consequences of the Offer and the Merger”) is expected (except to the extent any portion of such payment is required to be treated as imputed interest as defined below in “Special Factors—Section 7. Certain U.S. Federal Income Tax Consequences of the Offer and the Merger”) to recognize income, gain or loss equal to the difference, if any, between: (i) the sum of the Cash Amount received plus the fair market value (determined as of the closing of the Offer or the Effective Time, as the case may be) of any CVRs received; and (ii) the U.S. Holder’s adjusted tax basis in the Shares sold or exchanged. We urge you to consult your own tax advisor as to the particular tax consequences to you of the Offer and the Merger (including the application and effect of any state, local or non-U.S. income and other tax laws). See “Special Factors—Section 7. Certain U.S. Federal Income Tax Consequences of the Offer and the Merger” for a more detailed discussion of certain U.S. federal income tax consequences of the Offer and the Merger.

The U.S. federal, state, local and non-U.S. income and other tax consequences to holders or beneficial owners of Company Stock Options or Company Restricted Stock Units participating in the Merger with respect to such Company Stock Options or Company Restricted Stock Units are not discussed herein, and such holders or beneficial owners of Company Stock Options or Company Restricted Stock Units are strongly encouraged to consult with their own tax advisors regarding such tax consequences. We urge you to consult with your own tax advisor as to the particular tax consequences to you of the Offer and the Merger.

WILL I HAVE THE RIGHT TO HAVE MY SHARES APPRAISED?

•

No appraisal rights are available to the holders of Shares in connection with the Offer, and stockholders who tender their Shares in the Offer will not have appraisal rights in connection with the Merger. However, if Purchaser purchases Shares in the Offer and the Merger is consummated, holders of Shares outstanding as of immediately prior to the Effective Time who: (i) did not tender their Shares in the Offer (or, if tendered, validly and subsequently withdrew such Shares prior to the time Parent accepts properly tendered Shares for purchase); (ii) otherwise comply with the applicable procedures under Section 262 of the DGCL; and (iii) do not thereafter withdraw their demand for appraisal of such Shares or otherwise lose their appraisal rights, in each case in accordance with the DGCL, will be

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entitled to demand appraisal of their Shares and receive in lieu of the consideration payable in the Merger a cash payment equal to the “fair value” of their Shares, as determined by the Delaware Court of Chancery, in accordance with Section 262 of the DGCL plus interest, if any, on the amount determined to be the fair value.

•

The “fair value” of the Shares as determined by the Delaware Court of Chancery could be based upon considerations other than, or in addition to, the price paid in the Offer and the Merger and the market value of such Shares. Stockholders should recognize that the value determined in an appraisal proceeding of the Delaware Court of Chancery could be higher or lower than, or the same as, the Offer Price and that an investment banking opinion as to the fairness, from a financial point of view, of the consideration payable in a sale transaction, such as the Offer and the Merger, is not an opinion as to, and does not otherwise address, fair value under the DGCL. Moreover, Parent and Theseus may argue in an appraisal proceeding that, for purposes of such proceeding, the “fair value” of such Shares is less than the Offer Price.

•	Any stockholder who desires to exercise his, her or its appraisal rights should review carefully Section 262 of the DGCL and is urged to consult his, her or its legal advisor before electing or attempting to exercise such rights.

•

The foregoing summary of appraisal rights under the DGCL does not purport to be a statement of the procedures to be followed by stockholders desiring to exercise any appraisal rights under Delaware law. The preservation and exercise of appraisal rights require strict and timely adherence to the applicable provisions of Delaware law, which are contained in Section 262 of the DGCL and will be further summarized in a notice of the availability of appraisal rights to be sent by Theseus. The foregoing discussion is not a complete statement of law pertaining to appraisal rights under Delaware law and is qualified in its entirety by reference to Delaware law, including without limitation, Section 262 of the DGCL, a copy of which may be accessed without subscription or cost at the following publicly available website: https://delcode.delaware.gov/title8/c001/sc09/index.html#262. For more information regarding appraisal rights, see “The Tender Offer—Section 11. Certain Legal Matters; Regulatory Approvals.”

•	If you tender your Shares in the Offer, you will not be entitled to exercise appraisal rights with respect to your Shares but, instead, subject to the conditions to the Offer, you will receive the Offer Price for your Shares.

WITH WHOM MAY I TALK IF I HAVE QUESTIONS ABOUT THE OFFER?

•	You can call Morrow Sodali LLC, the Information Agent, toll-free at (800) 662-5200 or email them at THRX@investor.morrowsodali.com. See the back cover of this Offer to Purchase.

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To All Holders of Shares of

Theseus Pharmaceuticals, Inc.

INTRODUCTION

Purchaser, a wholly owned subsidiary of Parent, is making the Offer to acquire all outstanding Shares of Theseus for a cash amount per share of between $3.90 and $4.05, consisting of a Base Price Per Share of $3.90 and an Additional Price Per Share of up to $0.15, plus one non-transferable CVR for each Share, which represents the right to receive potential cash payments, contingent upon receipt of proceeds from any disposition of CVR Products within 180 days of the Closing Date and certain specified potential cost savings realized within 180 days of the Closing Date, as described in the CVR Agreement, all upon the terms and subject to the conditions described in this Offer to Purchase and in the related Letter of Transmittal. Pursuant to the Merger Agreement, the Additional Price Per Share, if any, will be determined based on Theseus’ good faith, estimated calculation of Closing Net Cash as of immediately prior to the Offer Closing Time. Parent and Purchaser will file with the SEC a supplement or amendment to this Offer to Purchase that includes the finally determined Additional Price Per Share no later than 9:00 a.m. Eastern Time on the first business day following the date on which the Closing Net Cash is finally determined and agreed upon by Theseus and Parent, and, pursuant to Rule 14e-1(b), the Offer will remain open for at least ten (10) business days from the date the supplement or amendment to this Offer to Purchase that includes the finally determined Additional Price Per Share is filed with the SEC. Subject to the terms of the Merger Agreement and the CVR Agreement, the Offer Price will be paid net of any applicable tax withholding and without interest. The Offer is being made pursuant to the Merger Agreement among Theseus, Parent and Purchaser, pursuant to which, after the completion of the Offer and the satisfaction or waiver of certain conditions, Purchaser will be merged with and into Theseus, without a meeting or any further action of the Theseus stockholders in accordance with Section 251(h) of the DGCL, assuming the conditions set forth in Section 251(h) of the DGCL are met, and Theseus will be the Surviving Corporation and a wholly owned subsidiary of Parent. Upon the terms and subject to the satisfaction or waiver of the conditions of the Offer and the Merger Agreement, including the satisfaction of the Minimum Tender Condition, Purchaser will accept for payment and thereafter pay for all Shares validly tendered and not validly withdrawn pursuant to the Offer at the Offer Closing Time.

Concurrently with the execution of the Merger Agreement, and as a condition and inducement to Theseus’ willingness to enter into the Merger Agreement and the CVR Agreement, the Guarantor has duly executed and delivered to Theseus the Limited Guaranty in favor of Theseus and the holders of CVRs, in respect of certain obligations of Parent and Purchaser under the Merger Agreement and certain obligations of Theseus as the Surviving Corporation under the CVR Agreement. The Guarantor’s obligations under the Limited Guaranty are subject to a cap of $177,614,912, plus certain enforcement costs, under the Merger Agreement and an amount equivalent to the CVR Proceeds (as defined below), plus certain enforcement costs, under the CVR Agreement. The Guarantor and TCM are considered co-offerors in the Offer. As co-offerors, the Guarantor and TCM accept joint responsibility for the accuracy of the disclosures made in this Offer to Purchase.

As noted in the Summary Term Sheet, there is a risk that: (i) you may receive no Additional Price Per Share as part of the Cash Amount; and (ii) you may receive no payments under the CVRs. Therefore, in making a decision to tender your Shares, you should understand that if the Additional Price Per Share is $0 and the CVR does not generate any payments, the only consideration that you would receive in the Offer is the Base Price Per Share of $3.90 that is being offered pursuant to the Offer. You should base your tender decision on the Base Price Per Share of $3.90 as it may be the only consideration you receive in the Offer. On January 8, 2024, the last full trading day prior to the date of this Offer to Purchase, the closing price of Theseus’ common stock as reported on Nasdaq was $4.00 per Share.

If your Shares are registered in your name and you tender directly to the Depositary and Paying Agent, you will not be obligated to pay brokerage fees or commissions or, except as otherwise provided in Instruction 6 of the Letter of Transmittal, transfer taxes on the purchase of Shares by Purchaser pursuant to the Offer. If you hold your Shares through a broker, dealer, commercial bank, trust company or other nominee you should check with such institution as to whether they charge any service fees or commissions.

We will pay all charges and expenses of the Depositary and Paying Agent and the Information Agent.

Purchaser shall not be required to accept for payment or, subject to any applicable rules and regulations of the SEC, including Rule 14e-1(c) under the Exchange Act (relating to Purchaser’s obligation

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to pay for or return tendered Shares promptly after the termination or withdrawal of the Offer), to pay for any Shares tendered pursuant to the Offer and, subject to the terms of the Merger Agreement, may delay the acceptance for payment of or payment for Shares or may terminate or amend the Offer, if:

(i)	prior to the Expiration Date, the Minimum Tender Condition shall have not been satisfied; or

(ii)	any of the conditions set forth in “The Tender Offer—Section 9. Conditions of the Offer” shall exist or shall have occurred and be continuing at the Expiration Date of the Offer.

Purchaser and Parent reserve the right to waive certain of the conditions to the Offer in their sole discretion (including the Minimum Cash Condition); provided that they may not waive the Minimum Tender Condition or the Termination Condition. See “The Tender Offer—Section 9. Conditions of the Offer.”

Pursuant to the terms of the Merger Agreement, the Offer and withdrawal rights will expire at one minute past 11:59 p.m. Eastern Time on February 7, 2024 (the “Expiration Date”). See “The Tender Offer —Section 1. Terms of the Offer,” “The Tender Offer—Section 9. Conditions of the Offer” and “The Tender Offer—Section 11. Certain Legal Matters; Regulatory Approvals.”

After careful consideration, the members of the Theseus Board have duly and unanimously: (i) determined that the terms of Offer, the Merger and the other transactions contemplated by the Merger Agreement and the CVR Agreement are fair to and in the best interests of Theseus and the Theseus’ stockholders, (ii) approved and declared advisable the Merger and the execution, delivery and performance by Theseus of the Merger Agreement and the consummation of the Transactions, (iii) resolved that the Merger Agreement and the Merger shall be governed by and effected under Section 251(h) of the DGCL, if the conditions of Section 251(h) are satisfied, and that the Merger shall be consummated as soon as practicable following the Offer Closing Time, and (iv) resolved to recommend that Theseus’ stockholders accept the Offer and tender their Shares pursuant to the Offer, which resolutions shall not be subsequently rescinded, modified or withdrawn in any way, except in connection with a Superior Company Proposal (as such term is used in the Merger Agreement).

For reasons considered by the Theseus Board, see Theseus’ Solicitation/Recommendation Statement on Schedule 14D-9 (the “Schedule 14D-9”) filed with the SEC on the date hereof in connection with the Offer, a copy of which (without certain exhibits) is being furnished to stockholders concurrently herewith.

The Offer is being made in connection with the Merger Agreement, pursuant to which, after the completion of the Offer and the satisfaction or waiver of certain conditions, the Merger will be effected. The Merger shall become effective when a certificate of merger is filed with the Secretary of State of the State of Delaware (or at such subsequent date and time as may be agreed by Parent, Theseus and Purchaser and specified in the certificate of merger).

Pursuant to the Merger Agreement, at the Effective Time, by virtue of the Merger and without any action on the part of the holders of Shares, each outstanding Share, other than Shares held in the treasury by Theseus, or by any stockholders of Theseus who are entitled to and who properly exercise appraisal rights under Delaware law, will be converted into the right to receive the Offer Price, without interest and subject to any applicable tax withholding. As of immediately prior to the Effective Time, each Company Stock Option and Company Restricted Stock Unit shall be accelerated and at the Effective Time (i)(A) each In-the-Money Option that is then outstanding will be cancelled and, in exchange therefor, the holder of such cancelled In-the-Money Option will be entitled to receive, in consideration of the cancellation of such In-the-Money Option, (1) an amount in cash, without any interest thereon and subject to applicable tax withholding, equal to the product of (x) the excess of the Cash Amount over the applicable exercise price per share under such In-the-Money Option and (y) the total number of Shares underlying such In-the-Money Option as of immediately prior to the Effective Time and (2) one CVR for each Share subject thereto and (B) each Out-of-the-Money Option will be cancelled for no consideration; and (ii) each outstanding Company Restricted Stock Unit shall be cancelled and the holder thereof shall be entitled to receive (A) an amount in cash without interest, less any applicable tax withholding, equal to the Cash Amount and (B) one CVR.

The Merger Agreement is more fully described in “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements,” which also contains a discussion of the treatment of Company Restricted Stock Units and Company Stock Options in the Merger. “Special Factors—Section 6. Certain

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U.S. Federal Income Tax Consequences of the Offer and the Merger” below describes certain U.S. federal income tax consequences generally applicable to Holders (as defined below) whose Shares are tendered and accepted for purchase pursuant to the Offer or whose Shares are exchanged in the Merger.

Because the Merger will be consummated in accordance with Section 251(h) of the DGCL, approval of the Merger will not require a vote of Theseus’ stockholders. Section 251(h) of the DGCL provides that stockholder approval of a merger is not required if certain requirements are met, including that: (i) the acquiring company consummates a tender offer for any and all of the outstanding stock of Theseus that, absent Section 251(h) of the DGCL, would be entitled to vote on the merger; (ii) following the consummation of such tender offer, the stock irrevocably accepted for purchase pursuant to such offer and received by the depositary prior to expiration of such offer, together with the stock otherwise owned by the consummating corporation or its affiliates and any “rollover stock” (as defined in Section 251(h) of the DGCL), equals at least such percentage of the stock of Theseus to be acquired that, absent Section 251(h) of the DGCL, would be required to adopt the Merger Agreement; and (iii) each outstanding share (other than “excluded stock” (as defined in Section 251(h) of the DGCL)) of the company that is subject of and not irrevocably accepted for purchase in such offer is converted in such merger into the right to receive the same amount and kind of cash, property, rights or securities paid for such shares pursuant to such offer. If the Minimum Tender Condition is satisfied and we accept Shares for payment pursuant to the Offer, we will hold a sufficient number of Shares to ensure that Theseus will not be required to submit the adoption of the Merger Agreement to a vote of its stockholders. As a result of the Merger, Theseus will cease to be a publicly traded company and will become a wholly owned subsidiary of Parent. See “Special Factors—Section 2. Purpose of the Offer and Plans for Theseus.”

The Merger Agreement, the CVR Agreement, the Limited Guaranty, this Offer to Purchase and the related Letter of Transmittal contain important information and should be read carefully and in their entirety before any decision is made with respect to the Offer.

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SPECIAL FACTORS

1.	BACKGROUND OF THE OFFER; CONTACTS WITH THESEUS.

Background of the Offer and the Merger; Past Contacts or Negotiations between Parent, Purchaser and Theseus. The following is a description of contacts between representatives of Parent and Purchaser with representatives of Theseus that resulted in the execution of the Merger Agreement and the agreements related to the Offer. For a review of Theseus’ activities relating to these contacts, please refer to Theseus’ Schedule 14D-9 being mailed to stockholders with this Offer to Purchase.

Background of the Offer and the Merger.

On November 24, 2023, Parent submitted a non-binding proposal to acquire 100% of the equity of Theseus for $3.80 per share in cash, plus a contingent value right for each share representing the right to receive 80% of the net proceeds payable from any license or disposition of Theseus’ programs (the “November 24 Proposal”). Later the same day, Parent, TCP, TCM and Kevin Tang, Chief Executive Officer of Parent, filed jointly a Schedule 13D with the SEC disclosing the submission of the November 24 Proposal.

On November 26, 2023, at the direction of the Theseus Board, representatives of Leerink Partners LLC, financial advisor to Theseus (“Leerink Partners”), contacted Mr. Tang to inform him that the Theseus Board received the November 24 Proposal and provided a draft of the Confidentiality Agreement.

On November 27, 2023, Theseus issued a press release confirming receipt of the November 24 Proposal and indicating that the Theseus Board was committed to acting in the best interests of all stockholders consistent with Theseus directors’ fiduciary duties.

On November 30, 2023, Theseus, Parent and TCP entered into the Confidentiality Agreement. On the same day, Theseus provided certain representatives of Parent and TCP with access to the Theseus’ electronic data room. Subsequently, due diligence review of non-public information regarding the Company was performed.

On December 4, 2023, Parent submitted a revised non-binding proposal to acquire 100% of the equity of Theseus for a cash price that is $10 million less than the net working capital at close minus projected ongoing costs that would be incurred post-close, including wind-down, legal, business development and intellectual property maintenance costs, plus a contingent value right representing the right to receive 80% of the net proceeds payable from any license or disposition of Theseus’ programs (the “December 4 Proposal”). In connection with the December 4 Proposal, Parent also provided a capabilities presentation providing a brief summary of the Parent and TCM and select business experience.

On December 4, 2023, representatives of Parent and TCP met with Theseus senior management, with representatives of Leerink Partners present, to discuss certain due diligence topics, including certain of Theseus’ clinical programs and publicly available financial information of Theseus. Additional due diligence review of non-public information regarding the Company was performed throughout the week of December 4, 2023.

On December 7, 2023, Parent submitted a second revised non-binding proposal to acquire 100% of the equity of Theseus for a cash price that is $10 million less than the net working capital at close minus transaction costs and projected ongoing costs that would be incurred post-close, including wind-down, legal, business development and intellectual property maintenance costs, plus two contingent value rights representing the right to receive (i) 80% of the net proceeds payable from any license or disposition of Theseus’ programs, and (ii) 50% of any net savings versus the closing net cash that is realized within 180 days of the close.

On December 8, 2023, Leerink Partners provided representatives from Parent and TCP with an initial draft of the Merger Agreement, which reflected the acquisition of Theseus by Concentra for an amount in cash, consisting of a base cash price per share and an additional cash amount per share at the closing of the merger, plus one non-tradeable contingent value right for each share representing the right to receive 80% of the net proceeds payable from any license or disposition of Theseus’ programs effected within 180 days of the close and 50% of any net savings versus the closing net cash that is realized within 180 days of the close. The initial draft Merger Agreement generally included customary terms and conditions for such an agreement including, among other things, for (i) the transaction to be structured as a cash tender offer followed immediately by a back-end merger pursuant to DGCL Section 251(h), (ii) the acceleration and cash out of certain Theseus equity awards, (iii) customary exceptions to the definition of “Company Material Adverse Effect,” which generally defines the

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standard for certain closing risk, (iv) customary representations and warranties with respect to Theseus and Parent and Purchaser, (v) Theseus’ ability to provide due diligence to, and negotiate a merger agreement with, a party making an unsolicited acquisition proposal that constitutes or would reasonably be expected to lead to a superior proposal and (vi) Theseus’ ability to terminate the Merger Agreement to accept a superior proposal after providing Parent with a right to match such proposal.

On December 11, 2023, Bradford D. Dahms, Theseus’ President and Chief Financial Officer, had a telephonic conversation with Mr. Tang regarding anticipated timing to sign a definitive merger agreement.

On December 12, 2023, Parent provided Leerink Partners with a revised draft of the Merger Agreement, which reflected certain revisions, including, among others, (i) a base cash price per share in cash of $3.80 and an additional amount per share in cash of up to $0.15; (ii) revisions to the scope of transaction expenses, (iii) an outside date 90 days following the date of Merger Agreement, (iv) a revised cap on Parent’s monetary damages under the Merger Agreement, (v) a Theseus termination fee of $3.6 million, (vi) insertion of a provision providing that Theseus would reimburse up to $1.25 million of Parent’s expenses in the event Parent terminates Merger Agreement due to Theseus’ failure to satisfy the closing net cash condition, and (vii) certain other revisions with respect to the representations and warranties and covenants.

On December 13, 2023, Leerink Partners provided representatives from Parent and TCP with an initial draft of the form of CVR Agreement (together with the Merger Agreement and other related documents, the “Transaction Documents”) and a revised draft of the Merger Agreement, which reflected certain revisions, including, among others, (i) a base price per share in cash of $3.94, (ii) an outside date 120 days following the date of Merger Agreement, (iv) a revised cap on Parent’s monetary damages under the Merger Agreement, (v) a revised Theseus termination fee and (vi) certain other revisions with respect to the representations and warranties and covenants.

On December 13, 2023, representatives of Parent and TCP met with Theseus senior management, with representatives of Leerink Partners present, to discuss certain due diligence topics. Additional due diligence review regarding the Company was performed throughout the remainder of the week of December 13, 2023 and December 18, 2023.

On December 16, 2023, Mr. Dahms had a telephonic conversation with Mr. Tang to discuss certain diligence items, anticipated timing to signing a definitive merger agreement, closing cash considerations and the base price per share. Following discussion, Mr. Dahms and Mr. Tang agreed that the next draft of the Merger Agreement would reflect a base price per share of $3.90 and an additional price per share of up to $0.15 per share, to be finally determined based on Theseus’ net cash at closing of the transaction.

On December 16, 2023, Parent provided Leerink Partners with a revised draft of the Merger Agreement, which reflected certain revisions, including, among others, (i) a base cash price per share in cash of $3.90, (ii) revisions to the scope of wind-down and post-closing costs to be accounted for in the closing net cash calculation, (iii) a revised Theseus termination fee, (iv) revision to the closing net cash condition and (v) certain other revisions with respect to the representations and warranties and covenants.

On December 18, 2023, Leerink Partners provided Parent with a revised draft of Merger Agreement, which reflected certain revisions, including, among others, (i) revisions to the cap on Parent’s monetary damages under the Merger Agreement, (ii) a revised Theseus termination fee, (iii) revision to the closing net cash condition and (iv) certain other revisions with respect to the representations and warranties and covenants.

On December 19, 2023, Mr. Dahms had a telephonic conversation with Mr. Tang to discuss certain diligence items, anticipated timing to signing a definitive merger agreement and closing cash considerations.

Also on December 19, 2023, Parent provided Leerink Partners with a revised draft of the CVR Agreement.

From December 20, 2023 to December 21, 2023, Mr. Tang and representatives of Parent, Purchaser and Gibson, Dunn & Crutcher LLP (“Gibson”), counsel to Parent, on one hand, and representatives of the Theseus senior management team, Leerink Partners and Goodwin Procter LLP (“Goodwin”), counsel to Theseus, on the other hand, exchanged drafts of the CVR Agreement, Limited Guaranty and Merger Agreement. Revisions to the Merger Agreement included revisions to (i) the scope of expenses to be accounted for in the calculation of closing net cash, (ii) the cap on Parent’s monetary damages under the Merger Agreement, (iv) the closing net cash condition and (iv) certain other revisions with respect to the representations and warranties and covenants.

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On December 20, 2023, Parent conveyed to Leerink Partners a desire for certain key investors to execute and deliver tender and support agreements concurrently with the execution of a definitive merger agreement. The same day, Parent provided Leerink Partners with an initial draft of the form of Support Agreement. Subsequently, representatives of Goodwin shared the draft form of Support Agreement with the previously identified investors.

On December 21, 2023, representatives of Gibson and Parent, on one hand, and representatives of Goodwin, on behalf of those certain identified investors, on the other hand, exchanged comments to the draft form of Support Agreement.

On December 22, 2023, the Merger Agreement was signed by Purchaser, Parent and Theseus and the Limited Guaranty was signed by TCP, Parent and Theseus.

On January 9, 2024, Purchaser commenced the Offer pursuant to the Merger Agreement, and Theseus filed a Schedule 14D-9.

2.	PURPOSE OF THE OFFER AND PLANS FOR THESEUS.

Purpose of the Offer. The purpose of the Offer and the Merger is for Parent, through Purchaser, to acquire control of, and the entire equity interest in, Theseus. Pursuant to the Merger, Parent will acquire all of the stock of Theseus not purchased pursuant to the Offer or otherwise.

Stockholders of Theseus who sell their Shares in the Offer will cease to have any equity interest in Theseus or any right to participate in its earnings and future growth.

Merger Without a Stockholder Vote. If the Offer is consummated, we do not anticipate seeking the approval of Theseus’ remaining public stockholders before effecting the Merger. Section 251(h) of the DGCL provides that following consummation of a successful tender offer for a public corporation, and subject to certain statutory provisions, if the acquiring corporation owns at least the amount of shares of each class of stock of the target corporation that would otherwise be required to adopt a merger agreement for the target corporation, and the other stockholders receive the same consideration for their stock in the merger as was payable in the tender offer, the acquiring corporation can effect a merger without the action of the other stockholders of the target corporation. Accordingly, if we consummate the Offer, we intend to effect the closing of the Merger without a vote of the stockholders of Theseus in accordance with Section 251(h) of the DGCL, upon the terms and subject to the satisfaction or waiver of the conditions to the Merger, as soon as practicable after the consummation of the Offer. Accordingly, we do not expect there to be a significant period of time between the consummation of the Offer and the consummation of the Merger.

Plans for Theseus. At the Effective Time, the certificate of incorporation of Theseus will be amended and restated in its entirety pursuant to the terms of the Merger Agreement. As of the Effective Time, the bylaws of the Surviving Corporation will be amended and restated to conform to the bylaws of Purchaser as in effect immediately prior to the Effective Time, except that references to the name of Purchaser will be replaced by references to the name of the Surviving Corporation. Purchaser’s directors immediately prior to the Effective Time will be the initial directors of the Surviving Corporation, and the officers of the Surviving Corporation shall be the respective individuals who served as the officers of Purchaser as of immediately prior to the Effective Time, in each case, until their respective successors are duly elected and qualified, or their earlier death, resignation or removal. Theseus will request each director of Theseus immediately prior to the Effective Time to execute and deliver a letter effectuating his or her resignation as a member of the Theseus Board. The Surviving Corporation will not have any employees, but may engage former employees of Theseus as consultants to assist with the performance of the Surviving Corporation’s obligations under the CVR Agreement. No such terms have been agreed upon. See “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements—Governance of the Surviving Corporation.”

At the Effective Time, Purchaser will be merged with and into Theseus, the separate existence of Purchaser will cease, and Theseus will continue as the Surviving Corporation in the Merger. The common stock of Theseus will be delisted and will no longer be quoted on Nasdaq, and Theseus’ obligation to file periodic reports under the Exchange Act will be suspended, and Theseus will be privately held.

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Except as disclosed in this Offer to Purchase, Parent and Purchaser do not have any present plan or proposal that would result in the acquisition by any person of additional securities of Theseus, the disposition of securities of Theseus, an extraordinary corporate transaction, such as a merger, reorganization or liquidation, involving Theseus or any of its subsidiaries or the purchase, sale or transfer of a material amount of assets of Theseus or any of its subsidiaries.

3.	REPORTS, OPINIONS, APPRAISALS AND NEGOTIATIONS.

Theseus, based on the determination of their Board of Directors to do so, retained Leerink Partners as its financial advisor in connection with the Offer, the Merger and the Transactions. In connection with this engagement, the Theseus Board requested that Leerink Partners evaluate the fairness, from a financial point of view, to the holders of Shares (other than certain excluded Shares) of the Cash Amount proposed to be paid to such holders pursuant to the terms of the Merger Agreement. On December 21, 2023, Leerink Partners rendered to the Theseus Board its oral opinion, which was subsequently confirmed by the delivery of a written opinion dated December 21, 2023. See “Special Factors—The Solicitation or Recommendation–Opinion of Leerink Partners LLC” and Annex I of the Schedule 14D-9, which information is hereby incorporated by reference.

None of Purchaser, Parent or the other TCP representatives engaged a financial advisor in connection with the Offer or the Merger.

4.	PRICE RANGE OF SHARES; DIVIDENDS.

According to Theseus’ Quarterly Report on Form 10-Q for the three and nine months ended September 30, 2023, the Shares are traded on Nasdaq under the symbol “THRX.” Theseus has advised Parent that, as of the close of business on January 8, 2024, there were: (i) 44,649,172 Shares issued and outstanding; (2) 6,221,333 Shares subject to outstanding Company Stock Options, 3,033,530 of which were In-the-Money Options assuming the maximum potential Cash Amount of $4.05 per Share; and (3) 87,605 Shares subject to outstanding Company Restricted Stock Units. The following table sets forth, for the fiscal quarters indicated, the high and low sales prices per Share on Nasdaq with respect to the fiscal years ended December 31, 2023 and 2022 and the current fiscal year.

Current Fiscal Year			High			Low
First Quarter (through January 8, 2024)			$4.13			$3.95

Fiscal Year Ended December 31, 2023	High	Low
First Quarter	$14.77	$5.03
Second Quarter	12.37	6.83
Third Quarter	10.26	2.60
Fourth Quarter	4.20	2.05

Fiscal Year Ended December 31, 2022	High	Low
First Quarter	$15.21	$7.95
Second Quarter	14.60	4.86
Third Quarter	9.35	5.22
Fourth Quarter	8.58	4.01

On January 8, 2024, the last full trading day prior to the date of this Offer to Purchase, the reported closing sales price per Share on Nasdaq during normal trading hours was $4.00 per Share.

Theseus has never paid cash dividends on its common stock. Additionally, under the terms of the Merger Agreement, Theseus is not permitted to declare or pay any dividends on or make other distributions in respect of any of its capital stock. See “The Tender Offer—Section 10. Dividends and Distributions.” Stockholders are urged to obtain a current market quotation for the Shares.

5.	POSSIBLE EFFECTS OF THE OFFER ON THE MARKET FOR THE SHARES; NASDAQ LISTING; EXCHANGE ACT REGISTRATION AND MARGIN REGULATIONS.

Possible Effects of the Offer on the Market for the Shares. The purchase of Shares pursuant to the Offer will reduce the number of Shares that might otherwise trade publicly and could adversely affect the liquidity and market value of the remaining Shares held by the public. The purchase of Shares pursuant to the Offer can also be expected to

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reduce the number of holders of Shares. We cannot predict whether the reduction in the number of Shares that might otherwise trade publicly would have an adverse or beneficial effect on the market price or marketability of the Shares or whether it would cause future market prices to be greater or less than the Offer Price.

Nasdaq Listing. Depending on the number of Shares purchased pursuant to the Offer, the Shares may no longer meet the requirements for continued listing on Nasdaq. According to the published guidelines of The Nasdaq Stock Market, LLC, Nasdaq would consider disqualifying the Shares for listing on Nasdaq if, among other possible grounds: (i) the total number of holders of record and holders of beneficial interest, taken together, in the Shares falls below 400; (ii) the bid price for a Share over a 30 consecutive business day period is less than $1.00; or (iii) (A) Theseus has stockholders’ equity of less than $10 million, the number of publicly held Shares falls below 750,000, the market value of publicly held Shares over a 30 consecutive business day period is less than $5 million or there are fewer than two active and registered market makers in the Shares over a ten consecutive business day period; (B) the number of publicly held Shares falls below 1,100,000, the market value of publicly held Shares over a 30 consecutive business day period is less than $15 million, there are fewer than four active and registered market makers in the Shares over a ten consecutive business day period, or the market value of Theseus’ listed securities is less than $50 million over a 30 consecutive business day period; or (C) the number of publicly held shares falls below 1,100,000, the market value of publicly held Shares over a 30 consecutive business day period is less than $15 million, there are fewer than four active and registered market makers in the Shares over a ten consecutive business day period, or Theseus’ total assets and total revenue is less than $50 million each for the most recently completed fiscal year (or in two of the last three fiscal years). Nasdaq has instituted temporary waivers of certain listing rules, but there can be no guarantee as to if or when these rules will be reinstated. Shares held by officers or directors of Theseus, or by any beneficial owner of more than 10 percent of the Shares, will not be considered as being publicly held for this purpose. According to Theseus, there were, as of January 8, 2024: (1) 44,649,172 Shares issued and outstanding; (2) 6,221,333 Shares subject to outstanding Company Stock Options, 3,033,530 of which were In-the-Money Options assuming the maximum potential Cash Amount of $4.05 per Share; and (3) 87,605 Shares subject to outstanding Company Restricted Stock Units. If, as a result of the purchase of Shares pursuant to the Offer or otherwise, the Shares are delisted from Nasdaq, the market for Shares will be adversely affected.

If Nasdaq were to delist the Shares, it is possible that the Shares would continue to trade on other securities exchanges or in the over-the-counter market and that price or other quotations for the Shares would be reported by other sources. The extent of the public market for such Shares and the availability of such quotations would depend, however, upon such factors as the number of stockholders and the aggregate market value of such securities remaining at such time, the interest in maintaining a market in the Shares on the part of securities firms, the possible termination of registration under the Exchange Act as described below, and other factors. We cannot predict whether the reduction in the number of Shares that might otherwise trade publicly would have an adverse or beneficial effect on the market price for or marketability of the Shares or whether it would cause future market prices to be greater or less than the Offer Price.

Trading in the Shares will cease upon consummation of the Merger if trading has not ceased earlier as discussed above.

Exchange Act Registration. The Shares currently are registered under the Exchange Act. The purchase of the Shares pursuant to the Offer may result in the Shares becoming eligible for deregistration under the Exchange Act. Registration of the Shares may be suspended by Theseus upon application to the SEC if the outstanding Shares are not listed on a “national securities exchange” and if there are fewer than 300 holders of record of Shares.

We intend to seek to cause Theseus to apply for suspension of registration of the Shares as soon as possible after consummation of the Offer if the requirements for suspension of registration are met. Suspension of registration of the Shares under the Exchange Act would reduce the information required to be furnished by Theseus to its stockholders and to the SEC and would make certain provisions of the Exchange Act (such as the short-swing profit recovery provisions of Section 16(b), the requirement of furnishing a proxy statement or information statement in connection with stockholders’ meetings or actions in lieu of a stockholders’ meeting pursuant to Sections 14(a) and 14(c) under the Exchange Act and the related requirement of furnishing an Annual Report to stockholders) no longer applicable with respect to the Shares. In addition, if the Shares are no longer registered under the Exchange Act, the requirements of Rule 13e-3 under the Exchange Act with respect to “going private” transactions would no longer be applicable to Theseus. Furthermore, the ability of “affiliates” of Theseus and persons holding “restricted securities” of Theseus to dispose of such securities pursuant to Rule 144

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under the Securities Act of 1933, as amended, may be impaired or eliminated. If registration of the Shares under the Exchange Act were suspended, the Shares would no longer be eligible for continued inclusion on the Board of Governors of the Federal Reserve System’s (the “Federal Reserve Board”) list of “margin securities” or eligible for stock exchange listing.

If registration of the Shares is not suspended prior to the Merger, then the registration of the Shares under the Exchange Act will be suspended following completion of the Merger.

Margin Regulations. The Shares are currently “margin securities” under the regulations of the Federal Reserve Board, which has the effect, among other things, of allowing brokers to extend credit using such Shares as collateral. Depending upon factors similar to those described above regarding listing and market quotations, following the Offer, the Shares may no longer constitute “margin securities” for the purposes of the margin regulations of the Federal Reserve Board, in which event the Shares would be ineligible as collateral for margin loans made by brokers.

6.	CERTAIN U.S FEDERAL INCOME TAX CONSEQUENCES OF THE OFFER AND THE MERGER.

The following summary describes certain U.S. federal income tax consequences generally applicable to Holders (as defined below) whose Shares are exchanged for cash and CVRs in the Offer or Merger. This summary is for general information purposes only and is not tax advice. This summary is based on the Code, U.S. Treasury regulations promulgated under the Code (“Treasury Regulations”), published rulings, administrative pronouncements and judicial decisions, all as in effect on the date hereof and all of which are subject to change or differing interpretations, possibly with retroactive effect. Any such change could affect the continuing validity of this summary. This summary addresses only Holders who hold their Shares as capital assets within the meaning of Section 1221 of the Code (generally, property held for investment) and does not address all of the tax consequences that may be relevant to Holders in light of their particular circumstances or to certain types of Holders subject to special treatment under the Code, including pass through entities (including partnerships and S corporations for U.S. federal income tax purposes) and partners or investors who hold their Shares through such entities, certain financial institutions, brokers, dealers or traders in securities or other persons that generally mark their securities to market for U.S. federal income tax purposes, insurance companies, expatriates, mutual funds, real estate investment trusts, regulated investment companies, cooperatives, tax-exempt organizations (including private foundations), retirement plans, controlled foreign corporations, passive foreign investment companies, persons who are subject to the alternative minimum tax, persons who hold their Shares as part of a straddle, hedge, conversion, constructive sale, synthetic security, integrated investment, or other risk-reduction transaction for U.S. federal income tax purposes, persons that have a functional currency other than the U.S. dollar, persons that own or have owned within the past five years (or are deemed to own or to have owned within the past five years) 5% or more of the outstanding Shares, Holders that exercise appraisal rights, Holders whose Shares are “qualified small business stock” within the meaning of Section 1202 of the Code or stock to which the rollover provisions of Section 1045 of the Code apply, and persons who acquired their Shares upon the vesting and cancellation of Company Stock Options or Company Restricted Stock Units in connection with the Merger or otherwise as compensation. This summary does not address any U.S. federal estate, gift, or other non-income tax consequences, the effects of the Medicare contribution tax, net investment income tax, or any state, local, or non-U.S. tax consequences.

As used in this summary, the term “U.S. Holder” means a beneficial owner of Shares that, for U.S. federal income tax purposes, is: (i) an individual who is a citizen or resident of the United States; (ii) a corporation, or other entity classified as a corporation for U.S. federal income tax purposes, that is created or organized in or under the laws of the United States or any state thereof or the District of Columbia; (iii) an estate, the income of which is subject to U.S. federal income taxation regardless of its source; or (iv) a trust if (A) a court within the United States is able to exercise primary supervision over the administration of the trust and one or more “U.S. persons” (within the meaning of Section 7701(a)(30) of the Code) has the authority to control all substantial decisions of the trust or (B) the trust has a valid election in effect under applicable Treasury Regulations to be treated as a U.S. person.

As used in this summary, the term “Non-U.S. Holder” means a beneficial owner of Shares that is neither a U.S. Holder nor a partnership for U.S. federal income tax purposes, and the term “Holder” or “Holders” means a U.S. Holder or a Non-U.S. Holder.

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If a partnership (including any entity or arrangement classified as a partnership for U.S. federal income tax purposes) exchanges Shares for cash and CVRs pursuant to the Offer or the Merger, the tax treatment of a partner in the partnership generally will depend upon the status of the partner, the activities of the partnership, and certain determinations made at the partner level. The partnership and partners of the partnership holding Shares should consult their tax advisors regarding the particular tax consequences of exchanging Shares for cash and CVRs pursuant to the Offer or the Merger applicable to them.

We have not sought, and do not expect to seek, a ruling from the IRS as to any U.S. federal income tax consequence described herein, and no assurance can be given that the IRS will not take a position contrary to the discussion below, or that a court will not sustain any challenge by the IRS in the event of litigation.

Holders are urged to consult their tax advisors to determine the tax consequences to them of exchanging Shares for cash and CVRs pursuant to the Offer or the Merger in light of their particular circumstances.

U.S. Holders.

The exchange of Shares for cash and CVRs pursuant to the Offer or the Merger will, depending on such U.S. Holder’s particular circumstances, generally be treated as a sale or exchange for U.S. federal income tax purposes or as a distribution with respect to such U.S. Holder’s Shares. A portion of the funds to pay for all Shares accepted for payment in the Offer and exchanged in the Merger will be funded by Theseus’ Closing Net Cash as finally determined pursuant to the Merger Agreement. As a result, the exchange of Shares for cash pursuant to the Offer or the Merger will be treated as a redemption of Shares by Theseus for U.S. federal income tax purposes. Under Section 302(b) of the Code, the exchange of Shares for cash pursuant to the Offer or the Merger generally will be treated as a “sale or exchange” if the exchange (i) results in a “complete termination” of the U.S. Holder’s interest in Theseus, (ii) is “substantially disproportionate” with respect to the U.S. Holder or (iii) is “not essentially equivalent to a dividend” with respect to the U.S. Holder (the “Section 302 tests”). In determining whether any of these tests has been met, Shares actually owned, as well as Shares considered to be owned by the U.S. Holder by reason of certain constructive ownership rules set forth in Section 318 of the Code (as modified by Section 302(c) of the Code), generally must be taken into account. U.S. Holders should be aware that acquisitions or dispositions of Shares as part of a plan that includes the U.S. Holder’s exchange of Shares pursuant to the Offer or the Merger may need to be taken into account in determining whether any of the Section 302 tests are satisfied. Due to the factual nature of these tests, U.S. Holders are urged to consult their own tax advisors to determine whether an exchange of Shares pursuant to the Offer or the Merger qualifies for sale or exchange treatment under these tests in light of their particular circumstances.

The exchange of Shares pursuant to the Offer or the Merger generally will result in a “complete termination” of the U.S. Holder’s interest in Theseus if either (i) the U.S. Holder owns no shares of Theseus’ common stock actually or constructively after the shares are sold pursuant to the Offer or the Merger or (ii) the U.S. Holder actually owns no shares of Theseus stock after the Offer or the Merger and, with respect to shares constructively owned, is eligible to waive, and effectively waives, constructive ownership of all such shares in accordance with the procedures described in Section 302(c)(2) of the Code. U.S. Holders wishing to satisfy the “complete termination” test through a waiver of attribution are urged to consult their own tax advisors concerning the mechanics and desirability of such a waiver.

The exchange of Shares pursuant to the Offer or the Merger generally will result in a “substantially disproportionate” redemption with respect to a U.S. Holder if the percentage of Theseus’ outstanding shares actually and constructively owned by the U.S. Holder immediately after the exchange is less than 80% of the percentage of Theseus’ outstanding shares actually and constructively owned by the U.S. Holder immediately before the exchange.

The exchange of Shares pursuant to the Offer or the Merger generally will be treated as “not essentially equivalent to a dividend” with respect to a U.S. Holder if the reduction in the U.S. Holder’s proportionate interest in Theseus’ stock as a result of the exchange constitutes a “meaningful reduction.” Whether the receipt of cash and CVRs by the U.S. Holder will be treated as not essentially equivalent to a dividend will depend on the particular facts and circumstances, including the number of shares of Theseus’ common stock purchased (or treated as purchased) by Theseus pursuant to the Offer or the Merger. However, in certain circumstances, even a small reduction in the percentage ownership interest of a stockholder whose relative stock interest in a publicly held corporation (such as Theseus) is minimal and who exercises no control over the corporation’s business may

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constitute a “meaningful reduction.” U.S. Holders are urged to consult their own tax advisors to determine the application of this test (and the other Section 302 tests) in light of their particular circumstances.

Because all of Theseus shares held by Holders will be sold pursuant to the Offer or the Merger, and Theseus will be wholly owned by Parent, it is expected, and the following discussion assumes, that the exchange of Shares for cash and CVRs will be treated as a “sale or exchange” for U.S. federal income tax purposes.

The amount of gain or loss a U.S. Holder recognizes, and the timing and character of a portion of such gain or loss, depends on the U.S. federal income tax treatment of the CVRs, with respect to which there is a significant amount of uncertainty. The installment method of reporting any gain attributable to the receipt of a CVR generally will not be available with respect to the disposition of Shares pursuant to the Offer or the Merger because the Shares are traded on an established securities market.

There is no legal authority directly addressing the U.S. federal income tax treatment of the receipt of the CVRs or payments received thereunder in connection with the Offer or the Merger. The receipt of the CVRs as part of the Offer or the Merger consideration might be treated as a “closed transaction” or as an “open transaction” for U.S. federal income tax purposes, or in some other manner, and such questions are inherently factual in nature. Accordingly, Holders are urged to consult with their tax advisors regarding this issue.

Pursuant to Treasury Regulations addressing contingent payment obligations analogous to the CVRs, if the fair market value of the CVR is “reasonably ascertainable,” a U.S. Holder should treat the transaction as a “closed transaction” and treat the fair market value of the CVRs as part of the consideration received in the Offer or the Merger for purposes of determining gain or loss. On the other hand, if the fair market value of the CVRs cannot be reasonably ascertained, a U.S. Holder may treat the transaction as an open transaction for purposes of determining gain or loss. These Treasury Regulations state that only in “rare and extraordinary” cases would the value of contingent payment obligations not be reasonably ascertainable. As noted above, there is no authority directly addressing whether contingent payment rights with characteristics similar to the rights under a CVR should be treated as “open transactions” or “closed transactions,” and such question is inherently factual in nature. The CVRs also may be treated as contract rights, debt instruments or deferred payment contract rights for U.S. federal income tax purposes, which would affect the amount, timing, and character of any gain, income or loss with respect to the CVRs. We urge you to consult your own tax advisor with respect to the proper characterization of the receipt of, and payments made with respect to, a CVR.

As a result, we cannot express a definitive conclusion as to the U.S. federal income tax treatment of receipt of the CVRs or receipt of any payment pursuant to the CVRs. However, to the extent required to take a position and except as otherwise required pursuant to applicable law, Theseus intends to treat the receipt of the CVRs as a closed transaction and payments received pursuant to the CVRs as amounts realized on the disposition (or partial disposition) of the CVRs. We cannot give any assurance that the IRS would not assert, or that a court would not sustain, a position contrary to this treatment. In such event, the tax consequences of the receipt of CVRs and/or payments with respect to the CVRs could differ materially from those summarized below (including, potentially, a portion or all of payments made with respect to the CVRs giving rise to ordinary income, rather than capital gain). No opinion of counsel or ruling has been or will be sought from the IRS regarding the tax treatment of the CVRs.

Treatment as Closed Transaction. If the receipt of a CVR is part of a closed transaction, a U.S. Holder generally would recognize capital gain or loss on a sale of Shares for the Offer Price pursuant to the Offer or an exchange of Shares for the Offer Price pursuant to the Merger, in an amount equal to the difference, if any, between: (i) the sum of the Cash Amount received plus the fair market value (determined as of the closing of the Offer or the Effective Time, as the case may be) of any CVRs received; and (ii) the U.S. Holder’s adjusted tax basis in the Shares sold or exchanged. Gain or loss generally would be calculated separately for each block of Shares (that is, Shares acquired at the same cost in a single transaction) tendered pursuant to the Offer or exchanged for the Offer Price pursuant to the Merger. The proper method to determine the fair market value of a CVR is not clear, but it is possible that the trading value of Theseus’ common stock would be considered along with other factors in making that determination. Any capital gain or loss recognized will be long-term capital gain or loss if the Holder’s holding period for such Shares exceeds one year. The deductibility of capital losses is subject to limitations.

The determination of whether a corporation has current or accumulated earnings or profits is complex and the legal standards to be applied are subject to uncertainties and ambiguities. Additionally, whether a corporation

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has current earnings and profits can be determined only at the end of the taxable year. Accordingly, if the exchange of Shares pursuant to the Offer or the Merger is treated as a distribution rather than a sale or exchange under Section 302 of the Code, the extent to which such exchange is treated as a dividend is unclear. Theseus does not expect to have current or accumulated earnings and profits, but no assurance can be given in this regard.

A U.S. Holder’s initial tax basis in a CVR received in either the Offer or the Merger would equal the fair market value of such CVR (determined as of the closing of the Offer or the Effective Time, as the case may be) as determined for U.S. federal income tax purposes. The holding period for a CVR would begin on the day following the date of the closing of the Offer or the Effective Time, as the case may be. Theseus intends to cooperate with the Paying Agent to send to each U.S. Holder an IRS Form 1099-B reflecting Theseus’ determination of the fair market value of the CVRs issued in the Offer or Merger. Such determination is not binding on the IRS as to the stockholder’s tax treatment or the fair market value of the CVRs.

As noted above, there is no authority directly addressing the U.S. federal income tax treatment of contingent payment rights with characteristics similar to the rights under the CVRs, and, therefore, the amount, timing and character of any gain, income or loss with respect to the CVRs is uncertain. For example, payments with respect to the CVRs could be treated as payments with respect to a sale or exchange of a capital asset or as giving rise to ordinary income. It is also possible that, were a payment to be treated as being with respect to the sale of a capital asset, a portion of such payment would constitute imputed interest, as described below. Theseus intends to treat any payment received by a U.S. Holder in respect of such CVRs (except to the extent any portion of such payment is required to be treated as imputed interest, as described below) as an amount realized on the disposition of the CVR by the U.S. Holder. Assuming that this method of reporting is correct, a U.S. Holder should recognize gain or loss equal to the difference between such payment (less any portion of such payment required to be treated as imputed interest, as described below) and the U.S. Holder’s adjusted tax basis in the CVR. The gain or loss should be long-term capital gain or loss if the U.S. Holder has held the CVR for more than one year at the time of such payment. Additionally, a U.S. Holder may recognize capital loss to the extent of any remaining basis after the expiration of any right to cash payments under such U.S. Holder’s CVR. The deductibility of capital losses is subject to limitations.

Treatment as Open Transaction. If the receipt of a CVR pursuant to the Offer or the Merger is treated under the open transaction method of accounting for U.S. federal income tax purposes, the fair market value of the CVR will not be treated as additional consideration for the Shares at the time the CVR is received, and the U.S. Holder will not have any tax basis in the CVR. Instead, the U.S. Holder will take payments pursuant to the CVRs into account when made or deemed made in accordance with the U.S. Holder’s regular method of accounting for U.S. federal income tax purposes. Generally, a portion of such payments will be treated as imputed interest, as described in more detail below, and the balance as additional consideration recognized in exchange for the Shares.

If the receipt of a CVR is part of an open transaction then, although not entirely clear, the sum of the Cash Amount received for a U.S. Holder’s Shares and the portion of the payments pursuant to the CVR that is not treated as imputed interest will generally be applied first against a U.S. Holder’s adjusted tax basis in the Shares and any excess treated as gain. A U.S. Holder will recognize capital loss with respect to a Share to the extent that the holder’s adjusted tax basis in such Share exceeds the sum of the Cash Amount received for a U.S. Holder’s Shares and the cash received pursuant to the CVR that is not treated as imputed interest, although it is possible that such U.S. Holder may not be able to recognize such loss until the resolution of all contingencies under the CVRs or possibly until such U.S. Holder’s abandonment of the U.S. Holder’s CVR. Any such capital gain or loss will be long-term capital gain or loss if the U.S. Holder’s holding period in the Share exceeds one year. The deductibility of capital losses is subject to limitations. Gain or loss generally will be determined separately for each block of Shares (that is, Shares of the same class acquired at the same cost on the same day) exchanged pursuant to the Offer or the Merger.

Imputed Interest. A portion of any payments pursuant to the CVRs that are made more than six months after the closing of the Offer or the Effective Time, as the case may be, may be treated as imputed interest, which would be ordinary income to the U.S. Holder of a CVR. The portion of any payment made with respect to a CVR treated as imputed interest under Section 483 of the Code will be determined at the time such payment is made and generally should equal the excess of: (i) the amount of the payment in respect of the CVRs; over (ii) the present value of such amount as of the closing of the Offer or the Effective Time, as the case may be,

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calculated using the applicable federal rate as the discount rate. The applicable federal rate is published monthly by the IRS. A U.S. Holder must include in its taxable income interest imputed pursuant to Section 483 of the Code (if any) using such Holder’s regular method of accounting for U.S. federal income tax purposes. However, because all the payments pursuant to the CVRs are expected to be made within 180 days of the Closing Date, as described in the CVR Agreement, none of the payments pursuant to the CVRs is expected to be treated as imputed interest.

Non-U.S. Holders.

Any gain realized by a Non-U.S. Holder upon the tender of Shares pursuant to the Offer or the exchange of Shares pursuant to the Merger, as the case may be, generally will not be subject to U.S. federal income tax unless (i) the gain is effectively connected with a U.S. trade or business of such Non-U.S. Holder (and, if an applicable income tax treaty so provides, is also attributable to a permanent establishment maintained by such Non-U.S. Holder in the United States), in which case the Non-U.S. Holder generally will be taxed in the same manner as a U.S. Holder (as described above under “U.S. Holders”), except that if the Non-U.S. Holder is a foreign corporation, an additional branch profits tax may apply at a rate of 30% (or a lower applicable treaty rate) or (ii) the Non-U.S. Holder is a nonresident alien individual who is present in the U.S. for 183 days or more in the taxable year of the closing of the Offer or the Effective Time, as the case may be, and certain other conditions are met, in which case the Non-U.S. Holder may be subject to a 30% U.S. federal income tax (or a tax at a reduced rate under an applicable income tax treaty) on such gain (net of certain U.S. source losses).

Generally, if payments are made to a Non-U.S. Holder with respect to a CVR, such Non-U.S. Holder may be subject to withholding at a rate of 30% (or a lower applicable treaty rate) on the portion of any such payments treated as imputed interest (as discussed above under “U.S. Holders—Imputed Interest”), or possibly the entire CVR payment depending on the U.S. federal income tax treatment of the CVRs, unless such Non-U.S. Holder establishes its entitlement to exemption from or a reduced rate of withholding under an applicable tax treaty by providing the appropriate documentation (generally, IRS Form W-8BEN or W-8BEN-E or other applicable IRS Form W-8) to the applicable withholding agents. As discussed above, the tax treatment of the CVRs is unclear, and it is possible that the Depositary, Paying Agent or other withholding agent may withhold additional amounts on payments with respect to the CVRs.

Amounts treated as imputed interest that are effectively connected with a Non-U.S. Holder’s conduct of a trade or business in the United States and, if required by an applicable income tax treaty, are attributable to a permanent establishment in the United States, are generally taxed in the manner applicable to U.S. Holders, as described above. In such cases, the Non-U.S. Holder will not be subject to withholding so long as such Non-U.S. Holder complies with applicable certification and disclosure requirements. In addition, dividends or interest received by a non-U.S. corporation that are effectively connected with the conduct of a trade or business in the United States may be subject to a branch profits tax at a 30% rate, or a lower rate specified in an applicable income tax treaty. See “The Tender Offer—Section 3. Procedures for Tendering Shares” for information regarding the application of U.S. federal income tax withholding to payments made to Non-U.S. Holders.

If any amounts withheld exceed the Non-U.S. Holder’s U.S. federal income tax liability, such Non-U.S. Holder may obtain a refund or credit of any excess amounts withheld by filing an appropriate claim for a refund with the IRS.

Non-U.S. Holders are urged to consult their own tax advisors regarding the particular tax consequences to them of exchanging Shares in the Offer or the Merger, including the application of the 30% U.S. federal withholding tax, their potential eligibility for a reduced rate of, or exemption from, such withholding tax, and their potential eligibility for, and procedures for claiming, a refund of any such withholding tax.

Information Reporting, Backup Withholding and FATCA. Information reporting generally will apply to payments to a Holder pursuant to the Offer or the Merger (including payments with respect to a CVR), unless such Holder is an entity that is exempt from information reporting and, when required, properly demonstrates its eligibility for exemption. Any payment to a U.S. Holder that is subject to information reporting generally will also be subject to backup withholding, unless such U.S. Holder: (i) provides the appropriate documentation (generally, IRS Form W-9) to the applicable withholding agent certifying that, among other things, its taxpayer identification number is correct, or otherwise establishes an exemption; and (ii) with respect to payments on the CVRs, provides the rights agent with the certification documentation in clause (i) of this sentence or otherwise establishes an exemption from backup withholding tax.

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The information reporting and backup withholding rules that apply to payments to a Holder pursuant to the Offer and Merger generally will not apply to payments to a Non-U.S. Holder if such Non-U.S. Holder certifies under penalties of perjury that it is not a U.S. person (generally by providing an IRS Form W-8BEN, IRS Form W-8BEN-E or other applicable IRS Form W-8) or otherwise establishes an exemption. Non-U.S. Holders should consult their own tax advisors to determine which IRS Form W-8 is appropriate.

As discussed above, Theseus intends to send to each U.S. Holder an IRS Form 1099-B treating the Offer or the Merger, as applicable, as a “closed transaction” for U.S. federal income tax purposes. Accordingly, U.S. Holders that treat the Offer or the Merger, as applicable, as an “open transaction” for U.S. federal income tax purposes are urged to consult their own tax advisors regarding how to accurately report their income under this method.

Certain Holders (including corporations) generally are not subject to backup withholding. Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules generally will be allowed as a refund or a credit against a U.S. Holder’s U.S. federal income tax liability if the required information is properly and timely furnished by such U.S. Holder to the IRS.

Under the “Foreign Account Tax Compliance Act” provisions of the Code, related U.S. Treasury guidance and related intergovernmental agreements (“FATCA”), the Depositary, Paying Agent or another applicable withholding agent will be required to withhold tax at a rate of 30% on payments of amounts treated as interest pursuant to U.S. tax law to any Non-U.S. Holder that fails to meet prescribed certification requirements. In general, no such withholding will be required with respect to a person that timely provides certifications that establish an exemption from FATCA withholding on a valid IRS Form W-8. A Non-U.S. Holder may be able to claim a credit or refund of the amount withheld under certain circumstances. Under currently proposed Treasury Regulations, FATCA withholding would no longer apply to payments that are treated as gross proceeds from the sale or other disposition of property of a type that can generate U.S. source interest or dividends, including the Shares. Taxpayers generally may rely on these proposed Treasury Regulations until final Treasury Regulations are issued. Each Non-U.S. Holder should consult its own tax advisor regarding the application of FATCA to the CVRs.

THE FOREGOING SUMMARY DOES NOT PURPORT TO BE A COMPLETE DISCUSSION OF THE POTENTIAL TAX CONSEQUENCES OF THE OFFER OR THE MERGER OR THE OWNERSHIP OF CVRS. EACH HOLDER SHOULD CONSULT ITS OWN TAX ADVISOR REGARDING THE U.S. FEDERAL, STATE AND LOCAL AND NON-U.S. INCOME, ESTATE AND OTHER TAX CONSIDERATIONS RELATING TO THE OFFER AND MERGER IN LIGHT OF ITS PARTICULAR CIRCUMSTANCES. THE U.S. FEDERAL, STATE, LOCAL AND NON-U.S. INCOME AND OTHER TAX CONSEQUENCES TO HOLDERS OR BENEFICIAL OWNERS OF COMPANY STOCK OPTIONS OR COMPANY RESTRICTED STOCK UNITS PARTICIPATING IN THE MERGER WITH RESPECT TO SUCH COMPANY STOCK OPTIONS OR COMPANY RESTRICTED STOCK UNITS ARE NOT DISCUSSED HEREIN, AND SUCH HOLDERS OR BENEFICIAL OWNERS OF COMPANY STOCK OPTIONS OR COMPANY RESTRICTED STOCK UNITS ARE STRONGLY ENCOURAGED TO CONSULT THEIR OWN TAX ADVISORS REGARDING SUCH TAX CONSEQUENCES. NOTHING IN THIS SUMMARY IS INTENDED TO BE, OR SHOULD BE CONSTRUED AS, TAX ADVICE.

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THE TENDER OFFER

1.	TERMS OF THE OFFER.

Upon the terms and subject to the prior satisfaction or waiver of the conditions of the Offer (including, if the Offer is extended or amended, the terms and conditions of any extension or amendment), we will accept for payment, purchase and pay for all Shares validly tendered prior to the expiration of the Offer, and not properly withdrawn in accordance with the procedures set forth in “The Tender Offer—Section 4. Withdrawal Rights.” The Offer will expire at one minute after 11:59 p.m. Eastern Time on February 7, 2024, unless extended in accordance with the terms of the Merger Agreement, in which event the term “Expiration Date” will mean the date to which the Expiration Date of the Offer is so extended.

Purchaser is offering to pay a cash amount per share of between $3.90 and $4.05, consisting of a Base Price Per Share of $3.90 and an Additional Price Per Share of up to $0.15 (the Base Price Per Share and the Additional Price Per Share are together referred to as the “Cash Amount”), plus one non-transferable CVR for each Share, which represents the right to receive potential cash payments, contingent upon receipt of proceeds from any disposition of CVR Products within 180 days of the Closing Date and certain specified potential cost savings realized within 180 days of the Closing Date, as described in the CVR Agreement, in each case, without interest and subject to any applicable tax withholding, upon the terms and subject to the conditions contained in this Offer to Purchase and in the related Letter of Transmittal. Pursuant to the Merger Agreement, the Additional Price Per Share, if any, will be determined based on Theseus’ good faith, estimated calculation of Closing Net Cash as of immediately prior to the Offer Closing Time (the “Cash Determination Time”). Parent and Purchaser will file with the SEC a supplement or amendment to this Offer to Purchase that includes the finally determined Additional Price Per Share no later than 9:00 a.m. Eastern Time on the first business day following the date on which the Closing Net Cash is finally determined and agreed upon by Theseus and Parent, and, pursuant to Rule 14e-1(b), the Offer will remain open for at least ten (10) business days from the date the supplement or amendment to this Offer to Purchase that includes the finally determined Additional Price Per Share is filed with the SEC. The total Cash Amount payable by the Purchaser pursuant to the Offer and the Merger Agreement will equal the quotient derived by dividing (A) (1) the Closing Net Cash, plus (2) the Aggregate Exercise Price, minus (3) $10,000,000; by (B) the Company Outstanding Shares. The Additional Price Per Share shall equal the Cash Amount as determined pursuant to the immediately preceding sentence, minus the Base Price Per Share.

As noted in the Summary Term Sheet, there is a risk that: (i) you may receive no Additional Price Per Share as part of the Cash Amount; and (ii) you may receive no payments under the CVRs. Therefore, in making a decision to tender your Shares, you should understand that if the Additional Price Per Share is $0 and the CVR does not generate any payments, the only consideration that you would receive in the Offer is the Base Price Per Share of $3.90 that is being offered pursuant to the Offer. You should base your tender decision on the Base Price Per Share of $3.90 as it may be the only consideration you receive in the Offer. On January 8, 2024, the last full trading day prior to the date of this Offer to Purchase, the closing price of Theseus’ common stock as reported on Nasdaq was $4.00 per Share.

The Offer is conditioned upon the satisfaction of the Minimum Tender Condition and the other conditions described in “The Tender Offer—Section 9. Conditions of the Offer.” We may terminate the Offer without purchasing any Shares if certain events described in “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements—Summary of the Merger Agreement—Termination” occur.

Purchaser expressly reserves the right, in its sole discretion, to: (i) waive, in whole or in part, any Offer Condition (including the Minimum Cash Condition), other than the Minimum Tender Condition or the Termination Condition; and/or (ii) modify the terms of the Offer in a manner not inconsistent with the Merger Agreement, except that Theseus’ consent is required for Purchaser to:

(A)	reduce the number of Shares subject to the Offer;

(B)	reduce the Offer Price below the Base Price Per Share;

(C)	waive, amend or modify the Termination Condition;

(D)	add to the Offer Conditions or impose any other conditions on the Offer or amend, modify or supplement any Offer Condition in any manner adverse to the holders of Shares;

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(E)	terminate, extend or otherwise modify the Expiration Date of the Offer other than as provided in the Merger Agreement;

(F)	change the form or terms of consideration payable in the Offer (provided that the determination of the final Cash Amount pursuant to the terms of the Merger Agreement above the Base Price Per Share will not constitute such a change);

(G)	otherwise amend, modify or supplement any of the terms of the Offer in any manner adverse to the holders of Shares; or

(H)	provide for any “subsequent offering period” within the meaning of Rule 14d-11 under the Exchange Act.

Upon the terms and subject to the satisfaction or waiver of the conditions of the Offer and the Merger Agreement, including the Minimum Tender Condition, Purchaser will, and Parent shall cause Purchaser to, accept for payment and thereafter pay for all Shares validly tendered and not validly withdrawn pursuant to the Offer promptly after the Expiration Date. The Offer will not permit Shares to be tendered pursuant to guaranteed delivery procedures.

If, on or before the Expiration Date, we increase the consideration being paid for Shares accepted for payment in the Offer, such increased consideration will be paid to all stockholders whose Shares are purchased in the Offer, whether or not such Shares were tendered before the announcement of the increase in consideration. We also expressly reserve the right to modify the terms of the Offer, subject to compliance with the Exchange Act, the Merger Agreement and the restrictions identified in paragraphs (A) through (H) above.

The Merger Agreement provides that, unless the Merger Agreement has been validly terminated in accordance with its terms, (A) Purchaser may elect to (and if so requested by Theseus, will) extend the Offer for one or more consecutive increments of such duration as requested by Theseus, but not more than 10 business days each, if at the scheduled Expiration Date of the Offer (i) any of the Offer Conditions (as set forth in “The Tender Offer—Section 9. Conditions of the Offer”) shall not have been satisfied or waived, until such time as such conditions shall have been satisfied or waived or (ii) the determination of the Closing Net Cash and resolution of any dispute thereof has not been finalized in accordance with the terms of the Merger Agreement, and (B) Purchaser shall, and Parent shall cause Purchaser to, extend the Offer for the minimum period required by any rule, regulation or interpretation or position of the SEC or the staff thereof or Nasdaq applicable to the Offer; provided that Purchaser shall not, and shall not be required to, extend the Offer beyond the Outside Date of 11:59 p.m., Eastern Time, on April 21, 2024.

See “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements.”

Except as set forth above, there can be no assurance that we will be required under the Merger Agreement to extend the Offer. During any extension of the initial offering period pursuant to the paragraphs above, all Shares previously tendered and not withdrawn will remain subject to the Offer and subject to withdrawal rights. See “The Tender Offer—Section 4. Withdrawal Rights.”

Without Theseus’ consent, there will not be a subsequent offering period for the Offer.

If, subject to the terms of the Merger Agreement, we make a material change in the terms of the Offer or the information concerning the Offer, or if we waive a material condition of the Offer, we will disseminate additional tender offer materials and extend the Offer if and to the extent required by Rules 14d-3(b)(1), 14d-4(d), 14d-6(c) and l4e-1 under the Exchange Act or otherwise. The minimum period during which a tender offer must remain open following material changes in the terms of the tender offer or the information concerning the tender offer, other than a change in the consideration offered or a change in the percentage of securities sought, will depend upon the facts and circumstances, including the relative materiality of the terms or information changes. With respect to a change in the consideration offered or a change in the percentage of securities sought, a tender offer generally must remain open for a minimum of 10 business days following the disclosure of such change to stockholders to allow for adequate disclosure to stockholders.

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We expressly reserve the right, in our sole discretion, subject to the terms and upon the conditions of the Merger Agreement and the applicable rules and regulations of the SEC, to not accept for payment any Shares if, at the expiration of the Offer, any of the conditions to the Offer set forth in “The Tender Offer—Section 9. Conditions of the Offer” have not been satisfied. Under certain circumstances, Parent and Purchaser may terminate the Merger Agreement and the Offer.

Any extension, waiver or amendment of the Offer or termination of the Offer will be followed, as promptly as practicable, by public announcement thereof, such announcement in the case of an extension to be issued not later than 9:00 a.m. Eastern Time on the next business day after the Expiration Date in accordance with the public announcement requirements of Rules 14d-3(b)(1), 14d-4(d) and 14e-1(d) under the Exchange Act. Without limiting our obligation under such rule or the manner in which we may choose to make any public announcement, we currently intend to make announcements by issuing a press release to the PR Newswire (or such other national media outlet or outlets we deem prudent) and making any appropriate filing with the SEC.

Promptly following the purchase of Shares in the Offer, we expect to complete the Merger without a vote of the stockholders of Theseus pursuant to Section 251(h) of the DGCL.

Theseus has agreed to provide us with its list of stockholders and security position listings for the purpose of disseminating the Offer to holders of Shares. This Offer to Purchase and the related Letter of Transmittal will be mailed to record holders of Shares whose names appear on Theseus’ stockholder list and will be furnished to brokers, dealers, commercial banks, trust companies and similar persons whose names, or the names of whose nominees, appear on the stockholder list or, if applicable, who are listed as participants in a clearing agency’s security position listing, for subsequent transmittal to beneficial owners of Shares.

2.	ACCEPTANCE FOR PAYMENT AND PAYMENT FOR SHARES.

Subject to the satisfaction or waiver of all the conditions to the Offer set forth in “The Tender Offer—Section 9. Conditions of the Offer,” we will immediately after the Expiration Date irrevocably accept for payment all Shares tendered (and not validly withdrawn) pursuant to the Offer and, promptly after the Expiration Date (and in any event within three business days), pay for such Shares.

In all cases, payment for Shares tendered and accepted for payment pursuant to the Offer will be made only after timely receipt by the Depositary and Paying Agent of: (i) certificates representing such Shares or confirmation of the book-entry transfer of such Shares into the Depositary and Paying Agent’s account at DTC pursuant to the procedures set forth in “The Tender Offer—Section 3. Procedures for Tendering Shares;” (ii) a Letter of Transmittal, properly completed and duly executed, with any required signature guarantees (or, in the case of a book-entry transfer, an Agent’s Message (as defined below) in lieu of the Letter of Transmittal); and (iii) any other documents required by the Letter of Transmittal or any other customary documents required by Depositary and Paying Agent. See “The Tender Offer—Section 3. Procedures for Tendering Shares.”

For purposes of the Offer, if and when Purchaser gives oral or written notice to the Depositary and Paying Agent of its acceptance for payment of such Shares pursuant to the Offer, then Purchaser has accepted for payment and thereby purchased Shares validly tendered and not validly withdrawn pursuant to the Offer. Upon the terms and subject to the conditions of the Offer, payment for Shares accepted for payment pursuant to the Offer will be made by deposit of the purchase price therefor with the Depositary and Paying Agent, which will act as agent for the tendering stockholders for purposes of receiving payments from us and transmitting such payments to the tendering stockholders. Under no circumstances will interest be paid on the Offer Price for Shares, regardless of any extension of the Offer or any delay in payment for Shares.

If any tendered Shares are not accepted for payment pursuant to the terms and conditions of the Offer for any reason, or if certificates are submitted for more Shares than are tendered, certificates for such unpurchased Shares will be returned (or new certificates for the Shares not tendered will be sent), without expense to the tendering stockholder (or, in the case of Shares tendered by book-entry transfer into the Depositary and Paying Agent’s account at DTC pursuant to the procedures set forth in “The Tender Offer—Section 3. Procedures for Tendering Shares,” such Shares will be credited to an account maintained with DTC) promptly following expiration or termination of the Offer.

3.	PROCEDURES FOR TENDERING SHARES.

Valid Tender of Shares. To validly tender Shares pursuant to the Offer, a properly completed and duly executed Letter of Transmittal in accordance with the instructions of the Letter of Transmittal, with any required

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signature guarantees, or an Agent’s Message (as defined below) in connection with a book-entry delivery of Shares, and any other documents required by the Letter of Transmittal and any other customary documents required by the Depositary and Paying Agent, must be received by the Depositary and Paying Agent at one of its addresses set forth on the back cover of this Offer to Purchase prior to the expiration of the Offer and either: (i) certificates representing Shares tendered must be delivered to the Depositary and Paying Agent; or (ii) such Shares must be properly delivered pursuant to the procedures for book-entry transfer described below and a confirmation of such delivery received by the Depositary and Paying Agent (which confirmation must include an Agent’s Message (as defined below) if the tendering stockholder has not delivered a Letter of Transmittal), in each case, prior to the Expiration Date. The term “Agent’s Message” means a message, transmitted by DTC to, and received by, the Depositary and Paying Agent and forming a part of a Book-Entry Confirmation (as defined below), which states that DTC has received an express acknowledgment from the participant in DTC tendering the Shares which are the subject of such Book-Entry Confirmation (as defined below) that such participant has received and agrees to be bound by the terms of the Letter of Transmittal and that Purchaser may enforce such agreement against the participant.

Book-Entry Transfer. The Depositary and Paying Agent will take steps to establish and maintain an account with respect to the Shares at DTC for purposes of the Offer. Any financial institution that is a participant in DTC’s systems may make a book-entry transfer of Shares by causing DTC to transfer such Shares into the Depositary and Paying Agent’s account in accordance with DTC’s procedures for such transfer. However, although delivery of Shares may be effected through book-entry transfer, either the Letter of Transmittal, properly completed and duly executed, together with any required signature guarantees, or an Agent’s Message in lieu of the Letter of Transmittal, and any other required documents, must, in any case, be transmitted to and received by the Depositary and Paying Agent at one of its addresses set forth on the back cover of this Offer to Purchase prior to the Expiration Date. The confirmation of a book-entry transfer of Shares into the Depositary and Paying Agent’s account at DTC as described above is referred to herein as a “Book-Entry Confirmation.”

Delivery of documents to DTC in accordance with DTC’s procedures does not constitute delivery to the Depositary and Paying Agent.

Signature Guarantees and Stock Powers. Except as otherwise provided below, all signatures on a Letter of Transmittal must be guaranteed by a financial institution (including most commercial banks, savings and loan associations and brokerage houses) that is a member in good standing of a recognized Medallion Program approved by the Securities Transfer Association, Inc., including the Security Transfer Agents Medallion Program, the New York Stock Exchange Medallion Signature Program and the Stock Exchanges Medallion Program (each, an “Eligible Institution”). Signatures on a Letter of Transmittal need not be guaranteed: (i) if the Letter of Transmittal is signed by the registered owner(s) (which term, for purposes of this section, includes any participant in any of DTC’s systems whose name appears on a security position listing as the owner of the Shares) of Shares tendered therewith and such registered owner has not completed the box entitled “Special Payment Instructions” or the box entitled “Special Delivery Instructions” on the Letter of Transmittal; or (ii) if such Shares are tendered for the account of an Eligible Institution. See Instructions 1 and 5 of the Letter of Transmittal. If the certificates for Shares are registered in the name of a person other than the signer of the Letter of Transmittal, or if payment is to be made or certificates for Shares not tendered or not accepted for payment are to be returned to a person other than the registered owner of the certificates surrendered, then the tendered certificates must be registered or accompanied by appropriate stock powers, in either case, signed exactly as the name or names of the registered owner(s) or holder(s) appear on the certificates, with the signatures on the certificates or stock powers guaranteed as described above. See Instructions 1 and 5 of the Letter of Transmittal.

If certificates representing Shares are forwarded separately to the Depositary and Paying Agent, a properly completed and duly executed Letter of Transmittal must accompany each delivery of certificates.

THE METHOD OF DELIVERY OF SHARES, THE LETTER OF TRANSMITTAL AND ALL OTHER REQUIRED DOCUMENTS, INCLUDING DELIVERY THROUGH DTC, IS AT THE ELECTION AND RISK OF THE TENDERING STOCKHOLDER. DELIVERY OF ALL SUCH DOCUMENTS WILL BE DEEMED MADE ONLY WHEN ACTUALLY RECEIVED BY THE DEPOSITARY (INCLUDING, IN THE CASE OF A BOOK-ENTRY TRANSFER, BY BOOK-ENTRY

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CONFIRMATION). IF SUCH DELIVERY IS BY MAIL, IT IS RECOMMENDED THAT ALL SUCH DOCUMENTS BE SENT BY PROPERLY INSURED REGISTERED MAIL WITH RETURN RECEIPT REQUESTED. IN ALL CASES, SUFFICIENT TIME SHOULD BE ALLOWED TO ENSURE TIMELY DELIVERY.

Other Requirements. Purchaser will pay for Shares tendered (and not validly withdrawn) pursuant to the Offer only after timely receipt by the Depositary and Paying Agent of: (i) certificates for (or a timely Book-Entry Confirmation with respect to) such Shares; (ii) a Letter of Transmittal, properly completed and duly executed, with any required signature guarantees (or, in the case of a book-entry transfer, an Agent’s Message in lieu of the Letter of Transmittal); and (iii) any other documents required by the Letter of Transmittal or any other customary documents required by the Depositary and Paying Agent. Accordingly, tendering stockholders may be paid at different times depending upon when certificates for Shares or Book-Entry Confirmations with respect to Shares are actually received by the Depositary and Paying Agent. Under no circumstances will Purchaser pay interest on the purchase price of Shares, regardless of any extension of the Offer or any delay in making such payment. If your Shares are held in street name (i.e., through a broker, dealer, commercial bank, trust company or other nominee), your Shares can be tendered by your nominee by book-entry transfer through the Depositary and Paying Agent.

Binding Agreement. Our acceptance for payment of Shares tendered pursuant to one of the procedures described above will constitute a binding agreement between the tendering stockholder and us upon the terms and subject to the conditions of the Offer.

Appointment as Proxy. By executing and delivering a Letter of Transmittal as set forth above (or, in the case of a book-entry transfer, by delivery of an Agent’s Message in lieu of a Letter of Transmittal), the tendering stockholder irrevocably appoints Purchaser’s designees as such stockholder’s proxies, each with full power of substitution, to the full extent of such stockholder’s rights with respect to the Shares tendered by such stockholder and accepted for payment by us and with respect to any and all other Shares or other securities issued or issuable in respect of such Shares on or after the date of the Merger Agreement. All such proxies and powers of attorney will be considered coupled with an interest in the tendered Shares. Such appointment is effective when, and only to the extent that, we accept for payment Shares tendered by such stockholder as provided herein. Upon the effectiveness of such appointment, all prior powers of attorney, proxies and consents given by such stockholder will be revoked, and no subsequent powers of attorney, proxies and consents may be given (and, if given, will not be deemed effective). Our designees will, with respect to the Shares or other securities and rights for which the appointment is effective, be empowered to exercise all voting and other rights of such stockholder as they, in their sole discretion, may deem proper at any annual, special, adjourned or postponed meeting of the stockholders of Theseus, by written consent in lieu of any such meeting or otherwise. We reserve the right to require that, in order for Shares to be deemed validly tendered, immediately upon our payment for such Shares we must be able to exercise full voting, consent and other rights to the extent permitted under applicable law with respect to such Shares and other securities, including voting at any meeting of stockholders or executing a written consent concerning any matter.

Determination of Validity. All questions as to the validity, form, eligibility (including time of receipt) and acceptance of any tender of Shares will be determined by us in our sole and absolute discretion, which determination will be final and binding, subject to the rights of the tendering holders of Shares to challenge our determination in a court of competent jurisdiction. Purchaser reserves the absolute right to reject any and all tenders determined by us not to be in proper form or the acceptance for payment of or payment for which may, in our opinion, be unlawful. Purchaser also reserves the absolute right to waive any defect or irregularity in the tender of any Shares of any particular stockholder whether or not similar defects or irregularities are waived in the case of any other stockholder. No tender of Shares will be deemed to have been validly made until all defects and irregularities relating thereto have been cured or waived. None of Parent, Purchaser or any of their respective affiliates or assigns, the Depositary and Paying Agent, the Information Agent, or any other person will be under any duty to give notification of any defects or irregularities in tenders or incur any liability for failure to give any such notification. Purchaser’s interpretation of the terms and conditions of the Offer (including the Letter of Transmittal and the instructions thereto and any other documents related to the Offer) will be final and binding, subject to the rights of the tendering holders of Shares to challenge our determination in a court of competent jurisdiction.

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4.	WITHDRAWAL RIGHTS.

Except as otherwise provided in this Section 4, tenders of Shares pursuant to the Offer are irrevocable. However, a stockholder has withdrawal rights that are exercisable until the expiration of the Offer (i.e., at any time prior to one minute after 11:59 p.m. Eastern Time on February 7, 2024), or in the event the Offer is further extended, on such date and time to which the Offer is extended. In addition, pursuant to Section 14(d)(5) of the Exchange Act, Shares may be withdrawn at any time after March 9, 2024, which is the 60th day after the date of the commencement of the Offer, unless prior to that date Purchaser has accepted for payment the Shares validly tendered in the Offer.

For a withdrawal of Shares to be effective, a written or facsimile transmission notice of withdrawal must be timely received by the Depositary and Paying Agent at one of its addresses set forth on the back cover of this Offer to Purchase. Any notice of withdrawal must specify the name of the person having tendered the Shares to be withdrawn, the number of Shares to be withdrawn and the name of the record holder of the Shares to be withdrawn, if different from that of the person who tendered such Shares. The signature(s) on the notice of withdrawal must be guaranteed by an Eligible Institution, unless such Shares have been tendered for the account of any Eligible Institution. If Shares have been tendered pursuant to the procedures for book-entry transfer as set forth in “The Tender Offer—Section 3. Procedures for Tendering Shares,” any notice of withdrawal must specify the name and number of the account at DTC to be credited with the withdrawn Shares. If certificates representing the Shares have been delivered or otherwise identified to the Depositary and Paying Agent, the name of the registered owner and the serial numbers shown on such certificates must also be furnished to the Depositary and Paying Agent prior to the physical release of such certificates.

All questions as to the form and validity (including time of receipt) of any notice of withdrawal will be determined by us, in our sole discretion, which determination will be final and binding, subject to the rights of the tendering holders of Shares to challenge our determination in a court of competent jurisdiction. No withdrawal of Shares will be deemed to have been properly made until all defects and irregularities have been cured or waived. None of Parent, Purchaser or any of their respective affiliates or assigns, the Depositary and Paying Agent, the Information Agent, or any other person will be under any duty to give notification of any defects or irregularities in any notice of withdrawal or incur any liability for failure to give such notification. Withdrawals of tenders of Shares may not be rescinded, and any Shares properly withdrawn will be deemed not to have been validly tendered for purposes of the Offer. However, withdrawn Shares may be re-tendered by following one of the procedures for tendering Shares described in “The Tender Offer—Section 3. Procedures for Tendering Shares” at any time prior to the expiration of the Offer.

If Purchaser extends the Offer, delays its acceptance for payment of Shares, or is unable to accept for payment Shares pursuant to the Offer, for any reason, then, without prejudice to Purchaser’s rights pursuant to the Offer, the Depositary and Paying Agent may nevertheless, on Purchaser’s behalf, retain tendered Shares, and such Shares may not be withdrawn except to the extent that tendering stockholder’s exercise of withdrawal rights as described in this Section 4.

5.	CERTAIN INFORMATION CONCERNING THESEUS.

The following description of Theseus and its business has been taken from: (i) Theseus’ Annual Report on Form 10-K for the fiscal year ended December 31, 2022, filed with the SEC on March 9, 2023; and (iii) Theseus’ Periodic Report on Form 10-Q for the three and nine months ended September 30, 2023, filed with the SEC on November 17, 2023, and is qualified in its entirety by reference to such Form 10-K and Form 10-Q.

Theseus is a clinical-stage biopharmaceutical company focused on improving the lives of cancer patients through the discovery, development and commercialization of transformative targeted therapies. Theseus’ product candidate and development programs are designed to address drug resistance mutations in key driver oncogenes, which are mutated genes that cause cancer.

Theseus was incorporated under the laws of the State of Delaware on December 29, 2017. Theseus’ principal executive office is 314 Main Street, Cambridge, Massachusetts 02142, and Theseus’ telephone number is (857) 400-9491. Theseus’ website address is www.TheseusRx.com.

Available Information. Theseus is subject to the information and reporting requirements of the Exchange Act and in accordance therewith is obligated to file reports and other information with the SEC relating to its business, financial condition and other matters. Certain information, as of particular dates, concerning Theseus’

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business, principal physical properties, capital structure, material pending litigation, operating results, financial condition, directors and officers (including their remuneration and stock options granted to them), the principal holders of Theseus’ securities, any material interests of such persons in transactions with Theseus, and other matters is required to be disclosed in proxy statements and periodic reports distributed to Theseus’ stockholders and filed with the SEC. The SEC maintains an Internet website that contains reports, proxy statements and other information about issuers, such as Theseus, who file electronically with the SEC. The address of that site is https://www.sec.gov. Theseus also maintains an Internet website at https://www.TheseusRx.com. The information contained in, accessible from or connected to Theseus’ website is not incorporated into, or otherwise a part of, this Offer to Purchase or any of Theseus’ filings with the SEC. The website addresses referred to in this paragraph are inactive text references and are not intended to be actual links to the websites.

Sources of Information. Except as otherwise set forth herein, the information concerning Theseus contained in this Offer to Purchase has been based upon publicly available documents and records on file with the SEC, other public sources and information provided by Theseus. Although we have no knowledge that any such information contains any misstatements or omissions, none of the Guarantors, Parent, Purchaser or any of their respective affiliates or assigns, the Information Agent or the Depositary and Paying Agent assumes responsibility for the accuracy or completeness of the information concerning Theseus contained in such documents and records or for any failure by Theseus to disclose events which may have occurred or may affect the significance or accuracy of any such information.

6.	CERTAIN INFORMATION CONCERNING PARENT AND PURCHASER.

General. Purchaser is a Delaware corporation with its principal offices located at 4747 Executive Drive, Suite 210, San Diego, California 92121. The telephone number of Purchaser is (858) 281-5372. Purchaser is a wholly owned subsidiary of Parent. Purchaser was formed for the purpose of making a tender offer for all of the Shares of Theseus and has not engaged, and does not expect to engage, in any business other than in connection with the Offer and the Merger.

Parent is a Delaware limited liability company formed under the laws of the State of Delaware on March 8, 2023 with its principal offices located at 4747 Executive Drive, Suite 210, San Diego, California 92121. The telephone number of Parent is (858) 281-5372.

TCP is a Delaware limited partnership with its principal offices located at 4747 Executive Drive, Suite 210, San Diego, California 92121. The telephone number of TCP is (858) 200-3830.

TCM is the general partner of TCP and sole manager of Parent. TCM is a Delaware limited liability company with its principal offices located at 4747 Executive Drive, Suite 210, San Diego, California 92121. The telephone number of TCM is (858) 200-3830.

The name, citizenship, business address, business phone number, present principal occupation or employment and past material occupation, positions, offices or employment for at least the last five years for each director and each of the executive officers of Parent, Purchaser, TCP and TCM (the “Item 3 Persons”) and certain other information are set forth in Schedule A hereto.

During the last five years, none of Parent, Purchaser, TCP or TCM or, to the knowledge of Parent, Purchaser and the Guarantors, any of the Item 3 Persons: (i) has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors); or (ii) was a party to any judicial or administrative proceeding (except for matters that were dismissed without sanction or settlement and convictions that have been overturned on appeal) that resulted in a judgment, decree or final order enjoining the person from future violations of, or prohibiting activities subject to, federal or state securities laws, or a finding of any violation of such laws.

In the past 60 days, TCP purchased Theseus Shares by conducting open market purchases through the facilities of Nasdaq as follows: (i) on November 14, 2023, 303,532 shares at a price per share $3.19, (ii) on November 14, 2023, 500,000 shares at a price per share of $3.03, (iii) on November 14, 2023, 500,000 shares at a price per share of $3.04, (iv) on November 14, 2023, 500,000 shares at a price per share of $3.18, (v) on November 14, 2023, 500,000 shares at a price per share of $3.25, (vi) on November 14, 2023, 500,000 shares at a price per share of $3.22, (vii) on November 14, 2023, 3,966 shares at a price per share of $3.20, (viii) on November 15, 2023, 16,551 shares at a price per share of $3.22, (ix) on November 16, 2023, 88,442 shares at a price per share of $3.39, (x) on November 17, 2023, 82,914 shares at a price per share of $3.39, (xi) on

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November 20, 2023, 45,139 shares at a price per share of $3.37, (xii) on November 20, 2023, 4,595 shares at a price per share of $3.40, (xiii) on November 21, 2023, 20,974 shares at a price per share of $3.40, (xiv) on November 22, 2023, 2,600 shares at a price per share of $3.40, (xv) on November 24, 2023, 32,893 shares at a price per share of $3.56, (xvi) on November 29, 2023, 138,702 shares at a price per share of $3.76, (xvii) on November 30, 2023, 4,512 shares at a price per share of $3.80 and (xviii) on December 1, 2023, 10,206 shares at a price per share of $3.80. Except as set forth in the preceding sentence or as otherwise described in this Offer to Purchase: (A) none of Parent, Purchaser, TCP, TCM, any majority-owned subsidiary of Parent, Purchaser, TCP or TCM or, to the knowledge of Parent, Purchaser, TCP and TCM, any of the Item 3 Persons or any associate of any of the persons so listed beneficially owns or has any right to acquire, directly or indirectly, any Shares; and (B) none of Parent, Purchaser, TCP or TCM or, to the knowledge of Parent, Purchaser, TCP or TCM, any of the persons or entities referred to in clause (A) above nor any director, executive officer or subsidiary of any of the foregoing has effected any transaction in the Shares during the past 60 days. As of the date of this Offer to Purchase, TCP owns 3,255,026, or 7.3%, of the outstanding shares of Theseus’ Common Stock and will receive the Offer Price, including CVRs at Closing. As discussed in Section 10 – “Background of the Offer; Contacts with Theseus,” any Shares owned by directly or indirectly by Parent or Purchaser as of immediately prior to the Effective Time will be cancelled in the Merger for no consideration (including that no CVRs will be issued in respect of such Shares). There are no restrictions on any Theseus stockholder with respect to transferring or disposing of any such Shares prior to the Effective Time.

Except as otherwise described in this Offer to Purchase, none of Parent, Purchaser, TCP or TCM or, to the knowledge of Parent, Purchaser, TCP and TCM, any of the Item 3 Persons, has any contract, arrangement, understanding or relationship with any other person with respect to any securities of Theseus, including, but not limited to, any contract, arrangement, understanding or relationship concerning the transfer or voting of such securities, finder’s fees, joint ventures, loan or option arrangements, puts or calls, guarantees of loans, guarantees against loss, guarantees of profits, division of profits or loss or the giving or withholding of proxies.

Except as set forth in this Offer to Purchase, none of Parent, Purchaser, TCP or TCM or, to the knowledge of Parent, Purchaser, TCP or TCM, any of the Item 3 Persons, has had any business relationship or transaction with Theseus or any of its executive officers, directors or affiliates that is required to be reported under the rules and regulations of the SEC applicable to the Offer. Except as set forth in this Offer to Purchase, there have been no contacts, negotiations or transactions between Parent, Purchaser, TCP, TCM or any of their subsidiaries or, to the knowledge of Parent, Purchaser, TCP, TCM, any of the Item 3 Persons, on the one hand, and Theseus or its affiliates, on the other hand, concerning a merger, consolidation or acquisition, tender offer or other acquisition of securities, an election of directors or a sale or other transfer of a material amount of assets during the past two years.

Notwithstanding the foregoing, in connection with the execution of the Merger Agreement, Parent and Purchaser entered into Support Agreements (as described in “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements—Support Agreements”) with each of the Supporting Stockholders (as defined in “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements—Support Agreements”) that are party to the Support Agreements, which parties in the aggregate, beneficially own approximately 59% of the outstanding Shares.

Available Information. Pursuant to Rule 14d-3 under the Exchange Act, Parent and Purchaser filed with the SEC a Tender Offer Statement on Schedule TO (the “Schedule TO”), of which this Offer to Purchase forms a part, and exhibits to the Schedule TO. Copies of the Schedule TO and the exhibits thereto, and reports, proxy statements and other information may be obtained by mail, upon payment of the SEC’s customary charges, by writing to its principal office at 100 F Street, NE, Washington, DC 20549. The Schedule TO and the exhibits thereto, as well as other information filed by Parent and Purchaser with the SEC, are available at the SEC’s website on the Internet at www.sec.gov that contains the Schedule TO and the exhibits thereto and other information that Purchaser has filed electronically with the SEC.

7.	SUMMARY OF THE MERGER AGREEMENT AND CERTAIN OTHER AGREEMENTS.

Summary of the Merger Agreement.

The following summary of certain provisions of the Merger Agreement and all other provisions of the Merger Agreement discussed herein are qualified by reference to the Merger Agreement itself, which is incorporated herein by reference. The Merger Agreement was filed as Exhibit 2.1 to the Current Report on

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Form 8-K that Theseus filed with the SEC on December 22, 2023. The Merger Agreement may be examined and copies may be obtained at the places and in the manner set forth in “The Tender Offer—Section 6. Certain Information Concerning Parent and Purchaser.” Stockholders and other interested parties should read the Merger Agreement for a more complete description of the provisions summarized below. Capitalized terms used herein and not otherwise defined have the respective meanings set forth in the Merger Agreement.

The Merger Agreement has been included to provide investors and security holders with information regarding its terms. It is not intended to provide any other factual information about Theseus, Parent, Purchaser or their respective subsidiaries and affiliates. The Merger Agreement contains representations and warranties by Theseus, on the one hand, and Parent and Purchaser, on the other hand, made solely for the benefit of the other. The assertions embodied in those representations and warranties are subject to qualifications and limitations agreed to by the respective parties in negotiating the terms of the Merger Agreement, including information in confidential disclosure schedules delivered in connection with the signing of the Merger Agreement. Moreover, certain representations and warranties in the Merger Agreement were made as of a specified date, may be subject to a contractual standard of materiality different from what might be viewed as material to investors, or may have been used for the purpose of allocating risk between Theseus, on the one hand, and Parent and Purchaser, on the other hand, rather than establishing matters as facts. Accordingly, the representations and warranties in the Merger Agreement should not be relied on by any persons as characterizations of the actual state of facts about Theseus, Parent, Purchaser or their respective subsidiaries or affiliates at the time they were made or otherwise. In addition, information concerning the subject matter of the representations and warranties may change after the date of the Merger Agreement, which subsequent information may or may not be fully reflected in Theseus’ public disclosures.

The Offer. The Merger Agreement provides that Purchaser will commence the Offer no later than January 9, 2024. Purchaser’s obligation to accept for payment and pay for Shares validly tendered in the Offer is subject only to the satisfaction of the Minimum Tender Condition and the other Offer Conditions that are described in “The Tender Offer—Section 9. Conditions of the Offer.” Subject to the satisfaction of the Minimum Tender Condition and the other Offer Conditions that are described in “The Tender Offer—Section 9. Conditions of the Offer,” the Merger Agreement provides that Purchaser will, and Parent will cause Purchaser to, promptly after the applicable Expiration Date, as it may be extended pursuant to the terms of the Merger Agreement, irrevocably accept for payment and pay for all Shares validly tendered and not properly withdrawn pursuant to the Offer. Parent is entitled to use or cause to be used some or all of the Closing Net Cash in order to pay the Cash Amount for all such Shares.

Pursuant to the terms of the Merger Agreement, the Offer Price consists of (i) a cash amount per share of between $3.90 and $4.05, consisting of a Base Price Per Share of $3.90 and an Additional Price Per Share of up to $0.15 (the Base Price Per Share and the Additional Price Per Share are together referred to as the “Cash Amount”), (ii) plus one non-transferable CVR for each Share, which represents the right to receive potential cash payments, contingent upon receipt of proceeds from any disposition of CVR Products within 180 days of the Closing Date and certain specified potential cost savings realized within 180 days of the Closing Date, as described in the CVR Agreement, in each case, net of any applicable tax withholding and without interest. Pursuant to the Merger Agreement, the Additional Price Per Share, if any, will be determined based on Theseus’ good faith, estimated calculation of Closing Net Cash as of immediately prior to the Offer Closing Time. Parent and Purchaser will file with the SEC a supplement or amendment to this Offer to Purchase that includes the finally determined Additional Price Per Share no later than 9:00 a.m. Eastern Time on the first business day following the date on which the Closing Net Cash is finally determined and agreed upon by Theseus and Parent, and, pursuant to Rule 14e-1(b), the Offer will remain open for at least ten (10) business days from the date the supplement or amendment to this Offer to Purchase that includes the finally determined Additional Price Per Share is filed with the SEC.

Purchaser expressly reserves the right, in its sole discretion, to: (i) waive, in whole or in part, any Offer Condition described in “The Tender Offer—Section 9. Conditions of the Offer” (including the Minimum Cash Condition), other than the Minimum Tender Condition or the Termination Condition; and/or (ii) modify the terms of the Offer in a manner not inconsistent with the Merger Agreement, except that Theseus’ consent is required for Purchaser to:

(A)	reduce the number of Shares subject to the Offer;

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(B)	reduce the Offer Price below the Base Price Per Share;

(C)	waive, amend or modify the Termination Condition;

(D)	add to the Offer Conditions or impose any other conditions on the Offer or amend, modify or supplement any Offer Condition in any manner adverse to the holders of Shares;

(E)	except as provided in Section 2.01 of the Merger Agreement, terminate, extend or otherwise amend or modify the Expiration Date of the Offer other than as provided in the Merger Agreement;

(F)	change the form or terms of consideration payable in the Offer (provided that the determination of the final Cash Amount pursuant to the terms of the Merger Agreement above the Base Price Per Share will not constitute such a change);

(G)	otherwise amend, modify or supplement any terms of the Offer in a manner adverse to the holders of Shares; or

(H)	provide for any “subsequent offering period” within the meaning of Rule 14d-11 under the Exchange Act.

The Merger Agreement provides that, unless the Merger Agreement has been validly terminated in accordance with its terms, Purchaser may elect to (and if so requested by Theseus, will) extend the Offer: (A) for one or more consecutive increments of such duration as requested by Theseus, but not more than 10 business days each (or for such longer period as may be agreed to by Parent and Theseus), if at the scheduled Expiration Date of the Offer (i) any of the Offer Conditions (as set forth in “The Tender Offer—Section 9. Conditions of the Offer”) shall not have been satisfied or waived, until such time as such conditions shall have been satisfied or waived or (ii) the determination of the Closing Net Cash and resolution of any dispute thereof has not been finalized in accordance with the terms of the Merger Agreement, and (B) Purchaser shall, and Parent shall cause Purchaser to, extend the Offer for the minimum period required by any rule, regulation or interpretation or position of the SEC or the staff thereof or Nasdaq applicable to the Offer; provided that Purchaser be permitted or required to extend the Offer beyond the Outside Date.

Unless the Merger Agreement is terminated in accordance with its terms, Purchaser shall not terminate or withdraw the Offer prior to any scheduled expiration date. In the event the Merger Agreement is validly terminated in accordance with its terms, Purchaser will promptly and irrevocably terminate the Offer and return, and will cause any depository acting on behalf of Purchaser to return, all tendered Shares to the registered holders thereof.

Conversion of Capital Stock at the Effective Time. Each outstanding Share, other than Shares held in the treasury by Theseus, or by any stockholders of Theseus who are entitled to and who properly exercise appraisal rights under Delaware law, will be converted into the right to receive the Offer Price, without interest and subject to any applicable tax withholding.

Each share of Purchaser’s capital stock issued and outstanding immediately prior to the Effective Time will be converted into and become one fully paid and nonassessable share of common stock, par value $0.0001 per share, of the Surviving Corporation.

The Merger. The Merger Agreement provides that, as soon as practicable following the Offer Closing Time and subject to the terms and conditions of the Merger Agreement, and in accordance with the DGCL, at the Effective Time, Purchaser will be merged with and into Theseus, the separate existence of Purchaser will cease and Theseus will continue as the Surviving Corporation in the Merger. The Merger will be effected under Section 251(h) of the DGCL. Accordingly, Parent, Purchaser and Theseus have agreed to take all necessary and appropriate action to cause the Merger to become effective as soon as practicable following the consummation of the Offer without a vote of Theseus’ stockholders in accordance with Section 251(h) of the DGCL, upon the terms and subject to the satisfaction or waiver of the conditions to the Merger.

Immediately following the Effective Time, the certificate of incorporation of Theseus will be amended and restated in its entirety to be in the form attached as Exhibit B to the Merger Agreement and, as so amended and restated, will be the certificate of incorporation of the Surviving Corporation.

Immediately following the Effective Time, the bylaws of Purchaser as in effect immediately prior to the Effective Time will be the bylaws of the Surviving Corporation other than as set forth in the Merger Agreement.

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Treatment of Equity Awards. Pursuant to the Merger Agreement, as of immediately prior to the Effective Time, the vesting for each outstanding and unvested Company Stock Option and Company Restricted Stock Unit shall be accelerated and at the Effective Time (i)(A) each In-the-Money Option that is then outstanding will be cancelled and, in exchange therefor, the holder of such cancelled In-the-Money Option will be entitled to receive, in consideration of the cancellation of such In-the-Money Option, (1) an amount in cash, without any interest thereon and subject to applicable tax withholding, equal to the product of (x) the excess of the Cash Amount over the applicable exercise price per share under such In-the-Money Option and (y) the total number of Shares underlying such In-the-Money Option as of immediately prior to the Effective Time (the “Company Stock Option Cash Consideration”) and (2) one CVR for each Share subject thereto and (B) each Out-of-the-Money Option will be cancelled for no consideration; and (ii) each outstanding Company Restricted Stock Unit shall be cancelled and the holder thereof shall be entitled to receive (A) an amount in cash without interest, less any applicable tax withholding, equal to the Cash Amount and (B) one CVR.

Conditions to Each Party’s Obligation to Effect the Merger. The obligation of Theseus, Parent and Purchaser to effect the Merger is subject to the satisfaction or waiver on or prior to the Closing Date of the following conditions:

(i)	there must not be any judgment issued, or other legal restraint or prohibition imposed, in each case, by any governmental entity of competent jurisdiction, or law, in each case, (collectively, “Legal Restraints”) preventing or prohibiting the consummation of the Merger; and

(ii)	Purchaser must have accepted for payment all Shares validly tendered and not properly withdrawn pursuant to the Offer.

Theseus Board Recommendation. As described above, and subject to the provisions described below, the Theseus Board has determined to recommend that the stockholders of Theseus accept the Offer and tender their Shares to Purchaser in the Offer. The foregoing recommendation is referred to herein as the “Theseus Board Recommendation.” The Theseus Board also agreed to include the Theseus Board Recommendation with respect to the Offer in the Schedule 14D-9 and has permitted Parent to refer to such recommendation in this Offer to Purchase and documents related to the Offer.

Reasonable Best Efforts. Each of Theseus, Parent and Purchaser has agreed to use its respective reasonable best efforts to take, or cause to be taken, all actions that are necessary, proper or advisable to consummate and make the other transactions contemplated by the Merger Agreement (collectively, the “Transactions”). In particular, without limiting the generality of the foregoing, Theseus, Parent and Purchaser are required to use reasonable best efforts to: (i) cause each of the Offer Conditions and each of the conditions to the Merger to be satisfied as promptly as reasonably practicable, (ii) obtain all necessary or advisable actions or non-actions, waivers and consents from, or the making of all necessary registrations, declarations and filings with, and the taking of all reasonable steps as may be necessary to avoid a proceeding by, any governmental entity with respect to the Merger Agreement or the Transactions, (iii) defending or contesting of any proceedings, whether judicial or administrative, challenging the Merger Agreement or the consummation of the Transactions, including seeking to have any stay or temporary restraining order entered by any court or other governmental entity vacated or reversed and (iv) executing and delivering any additional instruments necessary to consummate the Transactions and to fully carry out the purposes of the Merger Agreement.

Termination. The Merger Agreement may be terminated prior to the Offer Closing Time as follows:

(i)	by mutual written consent of Parent, Purchaser and Theseus (in the case of Theseus, upon approval of the Special Committee);

(ii)	by either Parent or Theseus (in the case of Theseus, upon approval of the Special Committee) if:

(A) the Offer Closing Time shall not have occurred on or before 11:59 p.m. Eastern Time on April 21, 2024 (the “Outside Date”) or (B) the Offer shall have expired or been terminated in accordance with its terms and in accordance with the Merger Agreement without Purchaser having purchased any Shares; provided that this right to terminate the Merger Agreement shall not be available to a party if such occurrence is primarily due to a material breach of the Merger Agreement by such party; or

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any Legal Restraint permanently preventing or prohibiting the consummation of the Offer or the Merger shall be in effect and become final and non-appealable; provided, that this right to terminate the Merger Agreement shall not be available to a party if such Legal Restraint is primarily due to such party’s failure to comply with its reasonable best efforts obligations under Section 7.02 of the Merger Agreement, as described above;

(iii)

by Parent, if Theseus breaches or fails to perform any of its representations, warranties or covenants contained in the Merger Agreement, which breach or failure to perform individually or in the aggregate with all such other breaches or failures to perform (A) would result in the failure of an Offer Condition and (B) cannot be or has not been cured prior to the earlier of (x) 30 days after giving written notice to Theseus of such breach or failure to perform and (y) the Outside Date; provided that Parent and Purchaser are not then in material breach of the Merger Agreement (a “Theseus Breach Termination”);

(iv)	by Parent if an Adverse Recommendation Change has occurred;

(v)	by Parent if the Closing Net Cash as finally determined pursuant to the Merger Agreement is less than $187,614,912 (a “Minimum Cash Termination”);

(vi)

by Theseus (upon approval of the Special Committee), if (A) Purchaser fails to commence the Offer, except in the event of a violation by Theseus of its obligations under the Merger Agreement, (B) Purchaser shall have terminated the Offer prior to its expiration date (as may be extended) other than in accordance with the Merger Agreement, or (C) all of the Offer Conditions have been satisfied or waived (other than those conditions that by their nature are to be satisfied at the time Purchaser consummates the Offer, but subject to such conditions being able to be satisfied or waived) as of immediately prior to the expiration of the Offer and the Offer Closing Time shall not have occurred within five (5) business days following the expiration of the Offer;

(vii)

by Theseus (upon approval of the Special Committee), if Parent or Purchaser breaches or fails to perform any of its representations, warranties or covenants contained in the Merger Agreement, which breach or failure to perform (A) had or would reasonably be expected to, individually or in the aggregate with all such other breaches or failures to perform, result in a Parent Material Adverse Effect (as defined in the Merger Agreement) and (B) cannot be or has not been cured prior to the earlier of (x) thirty (30) days after the giving of written notice to Parent or Purchaser of such breach or failure to perform and (y) the Outside Date; provided that Theseus is not then in material breach of the Merger Agreement; or

(viii)

by Theseus (upon approval of the Special Committee), if (A) the Theseus Board (acting upon the recommendation of the Special Committee) or the Special Committee authorizes Theseus to enter into a definitive written agreement constituting a Superior Company Proposal (as defined below), (B) the Theseus Board and the Special Committee have complied in all material respects with their obligations under the Merger Agreement in respect of such Superior Company Proposal and (C) Theseus has paid, or simultaneously with the termination of the Merger Agreement pays, the Company Termination Fee (as defined below).

•

“Superior Company Proposal” means any written bona fide Company Takeover Proposal received after December 22, 2023 and that if consummated would result in a person or group (or the stockholders of any person) owning, directly or indirectly, (i) 50% or more of the aggregate voting power of the capital stock of Theseus or of the surviving entity or the resulting direct or indirect parent of Theseus or such surviving entity or (ii) 50% or more (based on the fair market value thereof, as determined in good faith by the Theseus Board (acting upon the recommendation of the Special Committee) or the Special Committee) of the assets of Theseus on terms and conditions which the Theseus Board (acting upon the recommendation of the Special Committee) or the Special Committee determines, in good faith, after consultation with outside counsel and its independent financial advisor, (A) would reasonably be expected to be more favorable from a financial point of view to the Theseus stockholders than the Transactions, taking into account all the terms and conditions (including all financial, regulatory, financing, conditionality, legal and other terms and conditions) of such proposal and the Merger Agreement; and (B) is reasonably likely to be completed.

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Termination Fee. Theseus has agreed to pay Parent a termination fee of $3,552,298 (the “Company Termination Fee”) if:

(i)	Theseus terminates the Merger Agreement pursuant to a termination in connection with a Superior Company Proposal (as defined above) as described in clause (viii) of “Termination” above;

(ii)	Parent terminates the Merger Agreement in the event an Adverse Recommendation Change occurs; or

(iii)

(A) after December 22, 2023, a bona fide Company Takeover Proposal is publicly proposed or announced or becomes publicly known or otherwise communicated to management of Theseus or the Theseus Board, and such Company Takeover Proposal is not publicly withdrawn or, if not publicly proposed or announced or communicated to the Theseus Board or management, has been withdrawn (x) in the case of a termination due to a material breach of the Merger Agreement, four (4) business days prior to the final expiration date of the Offer or (y) in the case of a Theseus Breach Termination, prior to the time of such breach, (B) the Merger Agreement is terminated pursuant to an due to a material breach of the Merger Agreement or a Theseus Breach Termination, and (C) within twelve (12) months after such termination, Theseus consummates, or enters into a definitive agreement with respect to, any Company Takeover Proposal.

•

For purposes of this “Termination Fee” (i) – (iii), the term “Company Takeover Proposal” means any inquiry, proposal or offer from any Person or group (other than Parent and its subsidiaries) relating to (i) any direct or indirect acquisition or purchase, in a single transaction or a series of related transactions, of (A) 50% or more (based on the fair market value thereof, as determined by the Company Board (acting upon the recommendation of the Special Committee) or the Special Committee) of the assets of the Company or (B) 50% or more of the aggregate voting power of the capital stock of the Company, (ii) any tender offer, exchange offer, merger, consolidation, business combination, recapitalization, liquidation, dissolution, binding share exchange or similar transaction involving the Company that, if consummated, would result in any Person or group (or the stockholders of any Person) beneficially owning, directly or indirectly, 50% or more of the aggregate voting power of the capital stock of the Company or of the surviving entity or the resulting direct or indirect parent of the Company or such surviving entity, other than, in each case, the Transactions or (iii) any combination of the foregoing.

Theseus is obligated to pay to Parent an expense reimbursement payment equal to the reasonable and documented out-of-pocket fees and expenses incurred by or on behalf of Parent or its affiliates in connection with the Transactions and the CVR Agreement up to a maximum of $1,250,000 if Parent terminates the Merger Agreement pursuant to a Minimum Cash Termination (the “Expense Reimbursement Payment”).

In the event Parent receives the Company Termination Fee or Expense Reimbursement Payment, such receipt will be deemed to be liquidated damages for any and all losses or damages suffered or incurred by Parent or Purchaser and constitute their sole and exclusive remedy against Theseus and its current, former or future stockholders and representatives for any loss suffered as a result of the failure of the Transactions to be consummated, and none of Theseus and its current, former or future stockholders or representatives will have any further liability or obligation relating to or arising out of the Merger Agreement or the Transactions, except as set forth in the Merger Agreement.

Effect of Termination. If the Merger Agreement is terminated pursuant to its terms, the Merger Agreement will become void and have no effect and there will be no liability or obligation on the part of Parent, Purchaser or Theseus following any such termination, except that: (i) certain specified provisions of the Merger Agreement will survive, including those described in “Termination Fee” above; (ii) the confidentiality agreement by and among Parent and Theseus will survive the termination of the Merger Agreement and remain in full force and effect in accordance with its terms; and (iii) termination will not relieve any party from liability for fraud or any willful and material breach of such party’s representations, warranties, covenants or agreements set forth in the Merger Agreement.

Conduct of Business Pending the Merger. Theseus has agreed that, from the date of the Merger Agreement until the earlier of the Offer Closing Time and the termination of the Merger Agreement in accordance with its terms, except as specifically provided by the Merger Agreement or as consented to in writing in advance by Parent, it will carry on its business in a manner consistent with the process related to the winding down of the Theseus and its subsidiaries, in a manner consistent with any applicable Contract terms, applicable Laws,

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applicable clinical standards and applicable ethical practices (the “Wind-Down Process”) and otherwise in the ordinary course of business. In addition, except as set forth in the Theseus Disclosure Letter or otherwise expressly and specifically permitted or required by the Merger Agreement or applicable law:

•

(i) enter into any new line of business or enter into any agreement, arrangement or commitment that is in excess of $25,000 or materially limits or otherwise restricts the Theseus or its affiliates, including, following the Merger Closing, Parent and its affiliates, from time to time engaging or competing in any line of business or in any geographic area or (ii) otherwise enter into any agreements, arrangements or commitments in excess of $25,000 or imposing material restrictions on its assets, operations or business;

•

(i) declare, set aside, establish a record date in respect of, accrue or pay any dividends on, or make any other distributions (whether in cash, stock, equity securities or property) in respect of, any of its capital stock, (ii) split, combine or reclassify any of its capital stock or issue or authorize the issuance of any other securities in respect of, in lieu of or in substitution for shares of its capital stock or (iii) repurchase, redeem, offer to redeem or otherwise acquire, directly or indirectly any shares of capital stock of the Company or options, warrants, convertible or exchangeable securities, stock-based performance units or other rights to acquire any such shares of capital stock, except for (A) acquisitions of Theseus Shares in connection with the surrender of Theseus Shares by holders of Company Stock Options and Company Restricted Stock Units outstanding on the Agreement Date, in the case of Company Stock Options, in order to pay the exercise price of Company Stock Options, (B) the withholding of shares of the Company Common Stock to satisfy Tax obligations with respect to awards granted pursuant to the Company Stock Plans outstanding on the Agreement Date, and (C) the acquisition by Theseus of Company Stock Options and Company Restricted Stock Units in connection with the forfeiture of such awards, in each case, in accordance with their terms;

•

issue, grant, deliver, sell, authorize, pledge or otherwise encumber any shares of its capital stock or options, warrants, convertible or exchangeable securities, stock-based performance units or other rights to acquire such shares, any Voting Company Debt or any other rights that give any person the right to receive any economic interest of any nature accruing to the holders of Theseus Shares, other than the Company Restricted Stock Units and issuances of Theseus Shares upon the exercise of Company Stock Options in accordance with their terms;

•	amend its certificate of incorporation, bylaws or other comparable organizational documents, other than immaterial or ministerial amendments;

•

form any subsidiary or acquire or agree to acquire, directly or indirectly, in a single transaction or a series of related transactions, whether by merging or consolidating with, or by purchasing a substantial equity interest in or a substantial portion of the assets of, or by any other manner, any assets outside of the ordinary course of business, any business or any corporation, partnership, limited liability company, joint venture, association or other business organization or division thereof or any other person;

•

other than as required pursuant to the terms of any Theseus benefit plan or benefit agreement in effect on the date of the Merger Agreement, (A) adopt or enter into any collective bargaining agreement, Theseus benefit plan or benefit agreement, (B) grant to any director, employee or individual service provider any increase in base compensation, (C) grant to any director, employee or individual service provider any increase in severance or termination pay, (D) pay or award, or commit to pay or award, any bonuses or incentive or equity compensation, (E) enter into any employment, retention, consulting, change in control, severance or termination agreement with any director, employee or individual service provider, (F) take any action to vest or accelerate any rights or benefits under any Theseus benefit plan or benefit agreement or (G) hire or terminate (other than for cause) the employment or service of any employee or individual service provider;

•	change its accounting methods, principles or practices, except as may be required by GAAP or by applicable law;

•	sell, lease, license, or otherwise transfer (including through any “spin-off”), or pledge, encumber or otherwise subject to any lien (other than a Permitted Lien (as defined in the Merger Agreement)), any

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properties or assets (other than intellectual property) except (i) sales or other dispositions of inventory and excess or obsolete properties or assets in the ordinary course of business, (ii) pursuant to Contracts to which Theseus is a party made available to Parent and in effect prior to the Agreement Date or (iii) in accordance with the Wind-Down Process;

•

sell, assign, lease, license, transfer, pledge, encumber or otherwise dispose of, permit to lapse or abandon, or, in the case of Trade Secrets, disclose to any third party, (i) any Trade Secret included in any Intellectual Property owned by Theseus or (ii) other than in accordance with the Wind-Down Process, any Intellectual Property owned by Theseus;

•

(i) incur or materially modify the terms of (including by extending the maturity date thereof) any indebtedness for borrowed money or guarantee any such indebtedness of another person, issue or sell any debt securities or warrants or other rights to acquire any debt securities of Theseus, guarantee any debt securities of another person, enter into any “keep well” or other agreement to maintain any financial statement condition of another person or enter into any arrangement having the economic effect of any of the foregoing or (ii) make any loans, advances or capital contributions to, or investments in, any other person;

•	make or agree to make any capital expenditures;

•

pay, discharge, settle, compromise or satisfy (A) any pending or threatened claims, liabilities or obligations relating to any proceeding (absolute, accrued, asserted or unasserted, contingent or otherwise), other than any such payment, discharge, settlement, compromise or satisfaction of a claim solely for money damages in the ordinary course of business in an amount not to exceed $25,000 per payment, discharge, settlement, compromise or satisfaction or $25,000 in the aggregate for all such payments, discharges, settlements, compromises or satisfactions, provided such amounts are taken into account in the calculation of Closing Net Cash or (B) any litigation, arbitration, proceeding or dispute that relates to the Transactions;

•	make, change or revoke any material tax election or any annual tax accounting period or adopt or change any material method of tax accounting;

•	amend, cancel or terminate any material insurance policy naming Theseus as an insured, a beneficiary or a loss payable payee without obtaining comparable substitute insurance coverage;

•	adopt a plan or agreement of complete or partial liquidation or dissolution, merger, consolidation, restructuring, recapitalization or other reorganization (other than the Merger);

•

Except in the ordinary course of business or in connection to the extent specifically permitted by any other subclause of this “Conduct of Business Pending the Merger” section, enter into, terminate or modify in any material respect, or expressly release any material rights under, any Material Contract (as defined in the Merger Agreement) or any contract that, if existing on the date of the Merger Agreement, would have been a Material Contract; or

•	renew or enter into any agreement containing a non-compete, exclusivity, non-solicitation or similar clause that would restrict or limit, in any material respect, the operations of Theseus or any of its Subsidiaries; or

•	authorize, commit or agree to take any of the foregoing actions.

Access to Information. Except if prohibited by applicable law, during the period prior to the earlier of the Effective Time or the termination of the Merger Agreement in accordance with its terms, Theseus will provide Parent and its Representatives reasonable access during normal business hours (under supervision of appropriate personnel and in a manner that does not unreasonably interfere with the normal operation of Theseus’ business) to its properties, books and records, contracts and personnel, and will furnish to Parent such information concerning Theseus’ business, properties and personnel as Parent or its representatives may reasonably request.

Security Holder Litigation. In the event that any litigation commences or is threatened in writing by or on behalf of one or more stockholders of Theseus against Theseus and its directors relating to any Transaction, Theseus has agreed to provide Parent an opportunity to review and propose comments to all material filings or responses to such litigation. Parent’s consent is required for Theseus to enter into, agree to or disclose any

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settlement with respect to any such litigation, except to the extent such settlement is covered by Theseus’ insurance policies or relates to the provision of additional disclosure in the Schedule 14D-9, but in each case, only if such settlement would not result in any restriction on the business or operations of Theseus or its affiliates. Theseus has an obligation to notify Parent of the commencement or written threat of any litigation and to keep Parent promptly and reasonably informed regarding any such litigation.

Indemnification, Exculpation and Insurance. All rights to indemnification and exculpation from liabilities for acts or omissions occurring at or prior to the Effective Time, and rights to advancement of expenses, existing in favor of any person who is, becomes, or has ever been, a director, officer, employee or agent (including as a fiduciary with respect to an employee benefit plan) of Theseus or its predecessors (each, an “Indemnified Party”), in each case, as provided in Theseus’ charter, bylaws or any indemnification agreement between Theseus and an Indemnified Party: (i) will be assumed by the Surviving Corporation at the Effective Time, (ii) will survive the Merger, (iii) will continue in full force and effect in accordance with their terms and (iv) for a period of six years following the date of the Merger Agreement, will not be amended, repealed or otherwise modified in any manner adverse to such Indemnified Party. Parent has agreed to ensure the Surviving Corporation complies with the foregoing obligations.

Stock Exchange Delisting and Deregistration. As promptly as practicable following the Effective Time, the Surviving Corporation will cause Theseus’ securities to be de-listed from Nasdaq and de-registered under the Exchange Act.

Section 16 Matters. Prior to the Effective Time, Parent will, and Theseus may, take all steps as may be required to cause any dispositions or cancellations of Theseus’ equity securities in connection with the Merger Agreement or the Transactions by each individual who is a director or officer of Theseus subject to Section 16 of the Exchange Act to be exempt under Rule 16b-3 under the Exchange Act.

Takeover Laws. Parent, Theseus and the Theseus Board have agreed to (i) take all actions within their power to ensure that no “business combination,” “control share acquisition,” “fair price,” “moratorium” or other anti-takeover law (each, a “Takeover Law”) is or becomes applicable to the Merger Agreement, the Offer, Offer Documents, the Merger or any of the other Transactions; and (ii) if any Takeover Law becomes applicable to the Merger Agreement, the Offer, Offer Documents, the Merger or any of the other Transactions, take all action within their power to ensure that the Offer, the Merger and the other Transactions may be consummated as promptly as practicable on the terms contemplated by the Merger Agreement and otherwise to minimize the effect of such statute or regulation on the Offer, the Merger and the other Transactions.

Governance of the Surviving Corporation. Immediately following the Effective Time, (i) the directors of the Purchaser immediately prior to the Effective Time will be appointed as the directors of the Surviving Corporation and (ii) the officers of Purchaser immediately prior to the Effective Time will become the officers of the Surviving Corporation.

Public Announcements. Parent, Purchaser and Theseus have agreed to consult with each other before issuing, and provide each other the opportunity to review and comment upon, any press release or other public statements with respect to the Offer, the Merger and the other Transactions, and shall not issue any such press release or make any such public statement prior to such consultation, except as may be required by applicable law, court process or by obligations pursuant to any listing agreement with any national or foreign securities exchange.

Representations and Warranties. This summary of the Merger Agreement has been included to provide investors with information regarding its terms. It is not intended to provide any other factual information about Parent, Purchaser or Theseus, their respective businesses, or the actual conduct of their respective businesses during the period prior to the consummation of the Offer or the Merger. The Merger Agreement contains representations and warranties that are the product of negotiations among the parties thereto and made to, and solely for the benefit of, each other as of the specified dates therein. The assertations embodied in those representations and warranties are subject to qualifications and limitations agreed to by the respective parties and are also qualified in important part by confidential disclosure scheduled delivered by Theseus to Parent in connection with the Merger Agreement.

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The representations and warranties were negotiated with the principal purpose of allocating risk among the parties to the agreements instead of establishing these matters as facts, and may be subject to standards of materiality applicable to the contracting parties that differ from those applicable to investors.

In the Merger Agreement, Theseus has made representations and warranties to Parent and Purchaser with respect to, among other things:

•	corporate matters, such as due organization, organizational documents, good standing, qualification,

•	capitalization;

•	subsidiaries;

•	power and authority and enforceability;

•	absence of conflicts and required consents and approvals;

•	SEC filings, financial statements and absence of undisclosed liabilities;

•	accuracy of information supplied for purposes of the Schedule 14D-9 and the Offer Documents;

•	absence of certain changes (including a Company Material Adverse Effect (as defined below)) since September 30, 2023;

•

taxes;

•	material contracts;

•	litigation;

•	real property;

•	compliance with laws;

•	regulatory matters;

•	environmental matters;

•	labor matters;

•	employee benefit plans;

•	intellectual property;

•	privacy and data security;

•	brokers’ fees and expenses

•	absence of a stockholder rights plan and Takeover Laws;

•	fairness opinion of financial advisor; and

•	absence of any requirement for stockholder votes or consents in accordance with Section 251(h) of the DGCL.

Some of the representations and warranties in the Merger Agreement made by Theseus are qualified as to “materiality” or a “Company Material Adverse Effect.” For purposes of the Merger Agreement, a “Company Material Adverse Effect” means any change, event, condition, development, circumstance, state of facts, effect or occurrence that has a material adverse effect on (i) the business, financial condition, assets, properties or results of operations of Theseus or (ii) the ability of Theseus to consummate the Transactions. Solely with respect to the foregoing clause (i) of the definition of Company Material Adverse Effect, a Company Material Adverse Effect does not include or take into account any change, event, condition, development, circumstance, state of facts, effect or occurrence to the extent resulting from or arising out of:

(i)	general conditions (or changes therein) in the industries in which Theseus operates;

(ii)	general economic or regulatory, legislative or political conditions (or changes therein), including any actual or potential stoppage, shutdown, default or similar event or occurrence affecting a national or

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federal government, or securities, credit, banking, financial or other capital markets conditions (including changes generally in prevailing interest rates, currency exchange rates, credit markets or equity price levels or trading volumes), in each case, in the United States, the European Union or elsewhere in the world;

(iii)

any change in applicable law or GAAP after the date of the Merger Agreement;

(iv)	geopolitical conditions, the outbreak or escalation of hostilities, any acts or threats of war (whether or not declared, including the ongoing conflict between Russia and Ukraine), sabotage or terrorism, or any escalation or worsening of any of the foregoing;

(v)

any epidemic, pandemic (including COVID-19), disease outbreak or other public health-related event (or escalation or worsening of any such events or occurrences, including, in each case, the response of governmental officials (including any quarantine, “shelter in place,” “stay at home,” social distancing, shutdown, closure, sequester or other law, order, directive, guideline or recommendation by any governmental entity or public health agency in connection with or in response to COVID-19), hurricane, tornado, flood, fire, volcano, earthquake or other natural or man-made disaster or any other national or international calamity, crisis or disaster;

(vi)

the failure, in and of itself, of Theseus to meet any internal or external forward-looking projections, forecasts, estimates or predictions in respect of any financial or operating metrics before, on or after the date of the Merger Agreement, or changes in the market price or trading volume of the Shares or the credit rating of Theseus (it being understood that the underlying facts giving rise or contributing to such failure or change may be taken into account in determining whether there has been a Company Material Adverse Effect if such facts are not otherwise excluded under this definition);

(vii)

the announcement, pendency or performance of any of the Transactions, including the identity of, or any facts or circumstances relating to, Parent, Purchaser or their respective affiliates, any stockholder litigation (direct or derivative) in respect of the Merger Agreement or any of the Transactions and any loss of or change in relationship, contractual or otherwise, with any governmental entity, supplier, vendor, service provider, collaboration partner, licensor, licensee or any other party having business dealings with Theseus, or departure of any employees or officers, of Theseus;

(viii)

Theseus’ compliance with the covenants contained in the Merger Agreement;

(ix)	any action taken by Theseus at Parent’s express written request or with Parent’s express written consent; or

(x)	any matter disclosed in Theseus’ confidential disclosure schedules delivered in connection with the Merger Agreement;

except in each case, with respect to clauses (i) through (v), to the extent Theseus is disproportionately affected thereby as compared with other participants in the industries in which Theseus operates (in which case the incremental disproportionate impact or impacts may be taken into account in determining whether there has been a Company Material Adverse Effect).

In the Merger Agreement, Parent and Purchaser have made representations and warranties to Theseus with respect to:

•	corporate matters, such as due organization, good standing, power and authority;

•	power and authority and enforceability;

•	absence of conflicts and required consents and approvals;

•	accuracy of information supplied for purposes of the Schedule 14D-9 and the Offer Documents;

•	broker’s fees and expenses;

•	litigation;

•	ownership of certain Theseus common stock; and

•	the Limited Guaranty.

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Some of the representations and warranties in the Merger Agreement made by Parent and Purchaser are qualified as to “materiality” or a “Parent Material Adverse Effect.” For purposes of the Merger Agreement, a “Parent Material Adverse Effect” means any change, effect, event or occurrence that prevents Parent or Purchaser from consummating the Offer, the Merger and the other Transactions on or before the Outside Date.

None of the representations, warranties, covenants or agreements in the Merger Agreement or in any instrument delivered pursuant to the Merger Agreement will survive the Effective Time, other than those covenants or agreements of the parties which by their terms apply, or are to be performed in whole or in part, after the Effective Time.

Specific Performance. The parties have agreed that irreparable damage would occur in the event that any of the provisions of the Merger Agreement were not performed in accordance with their specific terms or were otherwise breached, and that monetary damages, even if available, would not be an adequate remedy therefor. The parties further agreed that the parties will be entitled to an injunction or injunctions, or any other appropriate form of equitable relief, to prevent breaches of the Merger Agreement and to enforce specifically the performance of the terms and provisions of the Merger Agreement in Chancery Court of the State of Delaware (or in any federal court located in the State of Delaware if jurisdiction is not then available in the Chancery Court of the State of Delaware) in addition to any other remedy to which they are entitled at law or in equity.

Expenses. Except as otherwise provided in the Merger Agreement, all fees and expenses incurred by the parties in connection with the Merger Agreement and the Transactions will be paid by the party incurring such expenses, whether or not the Offer or the Merger is consummated.

Offer Conditions. The Offer Conditions are described in “The Tender Offer—Section 9. Conditions of the Offer.”

CVR Agreement. At or prior to the Offer Closing Time, Parent, Purchaser, the Rights Agent and the Representative will enter into the CVR Agreement governing the terms of certain contingent consideration payable thereunder. Each CVR will represent a contractual right to receive contingent cash payments equal to a pro rata share of: (i) 80% of the Net Proceeds (as defined in the CVR Agreement), if any, from any sale, transfer, license or other disposition (each, a “Disposition”) by Parent or any of its affiliates, including Theseus after the Merger, of all or any part of (a) Theseus’ product candidate known as THE-349, a fourth-generation epidermal growth factor receptor, or EGFR, inhibitor for the treatment of non-small cell lung cancer, (b) Theseus’ next-generation BCR-ABL program focused on relapsed/refractory chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia, or (c) Theseus’ KIT inhibitor program for the treatment of gastrointestinal stromal tumors (collectively, the “CVR Products” and such payment the “Disposition Proceeds”) which Disposition occurs within 180 days of the Closing Date (such period, the “Disposition Period”); and (ii) 50% of any net savings versus the Closing Net Cash that is realized between the date of the Closing Date and the end of the Disposition Period (such payment the “Further Savings Proceeds” and collectively with the Disposition Proceeds, the “CVR Proceeds”).

The CVRs are not deferred cash payments to Theseus stockholders, but instead are contractual rights to receive one or more payments in cash, contingent upon receipt of proceeds from the Disposition of CVR Products during the Disposition Period or net savings versus the Closing Net Cash that is realized within 180 days of the Closing Date. Theseus stockholders will be paid promptly in compliance with the prompt payment rules following such Disposition in the case of Disposition Proceeds or following the end of the Disposition Period in the case of Further Savings Proceeds. The rights of holders of CVRs will be fixed under the CVR Agreement. The CVRs represent the binding obligations of Parent under the CVR Agreement, and pursuant to Section 10.05 of the Merger Agreement, the holders of CVRs are intended third-party beneficiaries of the rights expressly provided for their benefit in the CVR Agreement. The co-offerors estimate that the amount that will be payable under the CVRs is most likely $0.00 per CVR.

The CVR Agreement provides the holders of CVRs certain contractual rights against Parent, Purchaser and the Rights Agent. The consent of the holders of at least 30% of the outstanding CVRs (the “Acting Holders”) is required any amendments to the CVR Agreement for the purpose of adding, eliminating, or changing provisions therein. The Acting Holders also have the right, on behalf of all holders of CVRs, to institute any action or proceeding at law, in equity, in bankruptcy or otherwise with respect to CVR Agreement, though no individual holder will be entitled to exercise such rights independently. Furthermore, the consent of the Representative is required for Parent or its affiliates to enter into any Disposition Agreement or other agreement providing for a change of control with Parent or its affiliates as the acquiror, licensee or recipient of any CVR Products.

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The right to payments under the CVRs as evidenced by the CVR Agreement is a contractual right only and will not be transferable, except in the limited circumstances specified in the CVR Agreement, including: (i) upon death of the holder by will or intestacy; (ii) pursuant to a court order; (iii) by operation of law (including a consolidation or merger) or without consideration in connection with the dissolution, liquidation or termination of any corporation, limited liability company, partnership or other entity; (iv) in the case of CVRs held in book-entry or other similar nominee form, from a nominee to a beneficial owner and, if applicable, through an intermediary, to the extent allowable by the Depository Trust Company (“DTC”); or (v) that CVRs may be abandoned. The CVRs are not securities, and therefore, will not be registered with the SEC.

The foregoing description of the CVR Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the form of the CVR Agreement, which is filed as Exhibit (d)(3) of the Schedule TO.

Support Agreements. In connection with the execution of the Merger Agreement, Parent and Purchaser entered into support agreements (the “Support Agreements”) with TCP, Foresite Capital Management, LLC and OrbiMed Advisors, LLC (the “Supporting Stockholders”). The Support Agreements provide that, among other things, the Supporting Stockholders irrevocably tender the Shares held by them in the Offer, upon the terms and subject to the conditions of such agreements. The Shares subject to the Support Agreements comprise approximately 59% of the outstanding Shares. The Support Agreements will terminate upon certain circumstances, including upon termination of the Merger Agreement or if Theseus Board votes to approve a superior proposal.

This summary and description of the material terms of the Support Agreements does not purport to be complete and is qualified in its entirety by reference to the Form of Support Agreement, which is filed as Exhibit (d)(6) to the Schedule TO and are incorporated by reference herein.

Confidentiality Agreement. On November 30, 2023, Theseus, Parent and TCP, entered into a confidentiality agreement (the “Confidentiality Agreement”), pursuant to which Parent and TCP agreed, subject to certain exceptions, to keep confidential all proprietary, nonpublic and/or confidential information about the other party, its affiliates or subsidiaries and/or its business furnished in connection with a possible negotiated transaction. Parent's and TCP’s obligations under the Confidentiality Agreement will expire one year after the date of the Confidentiality Agreement.

This summary and description of the material terms of the Confidentiality Agreement does not purport to be complete and is qualified in its entirety by reference to the Confidentiality Agreement, which is filed as Exhibit (d)(2) to the Schedule TO and is incorporated by reference herein.

Limited Guaranty. Concurrently with the execution of the Merger Agreement, and as a condition and inducement to Theseus’ willingness to enter into the Merger Agreement, Tang Capital Partners, LP, a Delaware limited partnership (“TCP”) (“Guarantor”) and sole member of Parent, delivered to Theseus a duly executed limited guaranty (the “Limited Guaranty”), dated as of the date of the Merger Agreement, in favor of Theseus, in respect of certain obligations of Parent and Purchaser under the Merger Agreement and the CVR Agreement. Certain obligations under the Limited Guaranty are subject to a cap of $177,614,912, plus certain enforcement costs, under the Merger Agreement and an amount equivalent to the CVR Proceeds (as defined below), plus certain enforcement costs, under the CVR Agreement.

8.	SOURCE AND AMOUNT OF FUNDS.

The Offer is not conditioned upon Parent’s, Purchaser’s or the Guarantor’s ability to finance the purchase of Shares pursuant to the Offer. Parent and Purchaser estimate that the total amount of funds required to consummate the Merger (including payments for the settlement and cancellation of Company Stock Options and Company Restricted Stock Units) pursuant to the Merger Agreement and to purchase all of the Shares pursuant to the Offer and the Merger Agreement is between approximately $177.6 million and $184.5 million, excluding any CVR Proceeds, depending on the finally determined Additional Price Per Share. The funds to pay for all Shares accepted for payment in the Offer may be funded entirely with Theseus’ available cash. Payments of CVR Proceeds, if any, will be paid with the Net Proceeds from the applicable Disposition of CVR Products, if any, and net savings versus the Closing Net Cash that are realized between the Closing Date and the end of the Disposition Period, if any.

In connection with the execution of the Merger Agreement, the Guarantor has agreed to the Limited Guaranty. Subject to the terms of the Limited Guaranty, the Guarantor has agreed to guarantee certain obligations of Parent and

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Purchaser up to $177,614,912, plus certain enforcement costs, under the Merger Agreement and certain obligations of Theseus up to an amount equivalent to the CVR Proceeds, plus certain enforcement costs, under the CVR Agreement. Other than the Limited Guaranty, there are no financing arrangements or alternative financing plans.

We do not believe our financial condition is relevant to your decision whether to tender your Shares and accept the Offer because: (i) the Offer is being made for all outstanding Shares solely for cash and CVRs; (ii) the Offer is not subject to any financing condition; (iii) if we consummate the Offer, we will acquire all remaining Shares for the same price in the Merger; (iv) the funds to pay for all Shares accepted for payment in the Offer may be funded entirely by Theseus’ available cash; and (v) the Guarantor has agreed to guarantee the obligations of Parent and Purchaser under the Merger Agreement, subject to the terms and conditions set forth in the Limited Guaranty. Payments to be made pursuant to the CVRs, if any, will be made with the Net Proceeds from the applicable Disposition of CVR Products, if any, and net savings versus the Closing Net Cash that are realized between the Closing Date and the end of the Disposition Period, if any. See “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements—CVR Agreement.” The CVRs will be the unsecured obligations of Theseus.

9.	CONDITIONS OF THE OFFER.

Notwithstanding any other term of the Offer or the Merger Agreement, Purchaser shall not be required to, and Parent shall not be required to cause Purchaser to, accept for payment or, subject to any applicable rules and regulations of the SEC, including Rule 14e-1(c) under the Exchange Act (relating to Purchaser’s obligation to pay for or return tendered Shares promptly after the termination or withdrawal of the Offer), to pay for any Shares tendered pursuant to the Offer and, subject to the terms of the Merger Agreement, may delay the acceptance for payment of or payment for Shares or may terminate or amend the Offer, if:

(a)	prior to the Expiration Date, there shall not have been validly tendered (and not properly withdrawn) at least one Share more than 50% of the number of Shares that are then issued and outstanding as of the expiration of the Offer (the “Minimum Tender Condition”); or

(b)	any of the following conditions exist or shall have occurred and be continuing at the Expiration Date:

(i)	there shall be any Legal Restraint (as defined in the Merger Agreement) in effect preventing or prohibiting the consummation of the Offer, the Merger or any of the other transactions contemplated by the Merger Agreement or CVR Agreement;

(ii)

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(iii)

the Merger Agreement shall have been validly terminated in accordance with its terms (the “Termination Condition”); or

(iv)	the Closing Net Cash as finally determined pursuant to Section 2.01(d) of the Merger Agreement is less than $187,614,912 (the “Minimum Cash Condition”).

The foregoing conditions shall be in addition to, and not a limitation of, the rights of Parent and Purchaser to extend, terminate or modify the Offer in accordance with the terms and conditions of the Merger Agreement. The foregoing conditions are for the sole benefit of Parent and Purchaser and, subject to the terms and conditions of the Merger Agreement and the applicable rules and regulations of the SEC, may be waived by Parent and Purchaser in whole or in part at any time and from time to time in their sole discretion. Such rights of termination are described above in “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements—Summary of the Merger Agreement—Termination.” All conditions (including the Minimum Cash condition), other than the Minimum Tender Condition and the Termination Condition may be waived by Parent or Purchaser in their sole discretion in whole or in part at any applicable time or from time to time, in each case subject to the terms and conditions of the Merger Agreement and the applicable rules and regulations of the SEC. The failure by Parent, Purchaser or any other Affiliate of Parent at any time to exercise any of the foregoing rights shall not be deemed a waiver of any such right, the waiver of any such right with respect to particular facts and circumstances shall not be deemed a waiver with respect to any other facts and circumstances and each such right shall be deemed an ongoing right that may be asserted at any time and from time to time. In accordance with SEC rules and regulations, upon discovery of a condition that gives rise to termination of the Offer, Parent and Purchaser will undertake to promptly notify Theseus stockholders of a decision to either terminate the Offer, or to waive the condition and proceed with the Offer.

10.	DIVIDENDS AND DISTRIBUTIONS.

The Merger Agreement provides that Theseus will not (subject to certain exceptions), between the date of the Merger Agreement and the Effective Time, declare, set aside or pay any dividends on, or make any other distributions (whether in cash, stock or property) in respect of, any of its capital stock (including the Shares) or other equity interests, except for dividends by a wholly owned subsidiary of Theseus to its parent. See “Special Factors—Section 4. Price Range of Shares; Dividends” and “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements—Conduct of Business Pending the Merger.”

11.	CERTAIN LEGAL MATTERS; REGULATORY APPROVALS.

General. Except as otherwise set forth in this Offer to Purchase, based on Parent’s and Purchaser’s review of publicly available filings by Theseus with the SEC and other information regarding Theseus, Parent and Purchaser are not aware of any licenses or other regulatory permits which appear to be material to the business of Theseus and which might be adversely affected by the acquisition of Shares by Purchaser pursuant to the Offer or of any approval or other action by any governmental, administrative or regulatory agency or authority which would be required for the acquisition or ownership of Shares by Purchaser or Parent pursuant to the Offer. In addition, except as set forth below, Parent and Purchaser are not aware of any filings, approvals or other actions by or with any governmental body or administrative or regulatory agency that would be required for Parent’s and Purchaser’s acquisition or ownership of the Shares. Should any such approval or other action be required, Parent and Purchaser have agreed to use reasonable best efforts to, in the most expeditious manner

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practicable, obtain all necessary actions or nonactions, waivers, consents, approvals, orders and authorizations from governmental entities, make all necessary registrations, declarations and filings and make all commercially reasonable efforts to obtain an approval or waiver from, or to avoid any action by, any governmental entity. The parties currently expect that such approval or action, except as described below under “Takeover Laws,” would be sought or taken. There can be no assurance that any such approval or action, if needed, would be obtained or, if obtained, that it will be obtained without substantial conditions; and there can be no assurance that, in the event that such approvals were not obtained or such other actions were not taken, adverse consequences might not result to Theseus’ or Parent’s business or that certain parts of Theseus’ or Parent’s business might not have to be disposed of or held separate. In such an event, we may not be required to purchase any Shares in the Offer. See “The Tender Offer—Section 9. Conditions of the Offer.”

Antitrust. Based on a review of the information currently available relating to the businesses in which Parent and Theseus are engaged and the consideration to be paid for the Shares, Parent and Purchaser have determined that no mandatory antitrust premerger notification filing or waiting period under Hart-Scott Rodino Antitrust Improvements Act of 1976, as amended (the “HSR”), and the rules and regulations promulgated thereunder is required, and therefore HSR clearance is not a condition to the consummation of the Offer or the Merger.

Based upon an examination of publicly available and other information relating to the businesses in which Theseus is engaged, Parent and Purchaser believe that the acquisition of Shares in the Offer (and the Merger) should not violate applicable antitrust laws. Nevertheless, Parent and Purchaser cannot be certain that a challenge to the Offer (and the Merger) on antitrust grounds will not be made, or, if such challenge is made, what the result will be. See “The Tender Offer—Section 9. Conditions of the Offer.”

Stockholder Approval Not Required. Assuming the Offer and the Merger are consummated in accordance with Section 251(h) of the DGCL, Theseus has represented in the Merger Agreement that execution, delivery and performance of the Merger Agreement by Theseus and the consummation by Theseus of the Offer and the Merger have been duly validly authorized by all necessary corporate action on the part of Theseus, and no other corporate proceedings on the part of Theseus are necessary to authorize the Merger Agreement or to consummate the Offer and the Merger. Section 251(h) of the DGCL provides that stockholder approval of a merger is not required if certain requirements are met, including that: (i) the acquiring company consummates an offer for all of the outstanding stock of the company to be acquired that, absent Section 251(h) of the DGCL, would be entitled to vote on such merger; (ii) following the consummation of such tender offer, the stock irrevocably accepted for purchase pursuant to the offer, together with the stock otherwise owned by the consummating company and its affiliates and any “rollover stock” (as defined in Section 251(h) of the DGCL), equals at least such percentage of the stock of the company to be acquired that, absent Section 251(h) of the DGCL, would be required to adopt the merger agreement; and (iii) the stockholders at the time of the merger receive the same consideration for their stock in the merger as was payable in the tender offer. If the Minimum Tender Condition is satisfied and we accept Shares for payment pursuant to the Offer, we will hold a sufficient number of Shares to ensure that Theseus will not be required to submit the adoption of the Merger Agreement to a vote of its stockholders. Following the consummation of the Offer and subject to the satisfaction of the remaining conditions set forth in the Merger Agreement, Purchaser, Parent and Theseus will take all necessary and appropriate action to effect the Merger as promptly as practicable without a meeting of stockholders of Theseus in accordance with Section 251(h) the DGCL. See “Special Factors—Section 2. Purpose of the Offer and Plans for Theseus” and “The Tender Offer—Section 7. Summary of the Merger Agreement and Certain Other Agreements.”

Takeover Laws. A number of states (including Delaware, where Theseus is incorporated) have adopted takeover laws and regulations which purport, to varying degrees, to be applicable to attempts to acquire securities of corporations which are incorporated in such states or which have substantial assets, stockholders, principal executive offices or principal places of business therein.

As a Delaware corporation, Theseus has not opted out of Section 203 of the DGCL. In general, Section 203 of the DGCL would prevent an “interested stockholder” (generally defined in Section 203 of the DGCL as a person beneficially owning 15% or more of a corporation’s voting stock and the affiliates and associates of such person) from engaging in a “business combination” (as defined in Section 203 of the DGCL) with a Delaware corporation for three years following the time such person became an interested stockholder unless, among other exceptions: (i) before such person became an interested stockholder, the board of directors of the corporation approved the transaction in which the interested stockholder became an interested stockholder or approved the business combination; (ii) upon consummation of the transaction which resulted in the interested stockholder becoming an interested stockholder, the interested stockholder owned at least 85% of the voting stock of the

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corporation outstanding at the time the transaction commenced (excluding for purposes of determining the number of shares of outstanding stock held by directors who are also officers and by employee stock plans that do not allow plan participants to determine confidentially whether to tender shares); or (iii) following the transaction in which such person became an interested stockholder, the business combination is: (A) approved by the board of directors of the corporation; and (B) authorized at a meeting of stockholders by the affirmative vote of the holders of at least 66 2/3% of the outstanding voting stock of the corporation not owned by the interested stockholder. The restrictions on business combinations contained in Section 203 of the DGCL also do not apply, among other possibilities, (i) to corporations that do not have a class of voting stock listed on a national securities exchange or held of record by more than 2,000 stockholders (unless the corporation’s certificate of incorporation expressly provides otherwise) or (ii) to interested stockholders who became interested stockholders at a time when the restrictions on business combinations did not apply because of the foregoing clause (i).

Theseus has represented to us in the Merger Agreement that the Theseus Board has taken all actions so that the restrictions applicable to business combinations contained in Section 203 of the DGCL are not, and will not be, applicable to the execution, delivery or performance of the Merger Agreement and the timely consummation of the Offer and the Merger and will not restrict, impair or delay the ability of Parent or Purchaser, after the Offer Closing Time, to vote or otherwise exercise all rights as a stockholder of Theseus. Purchaser has not attempted to comply with any other state takeover statutes in connection with the Offer or the Merger. Purchaser reserves the right to challenge the validity or applicability of any state law allegedly applicable to the Offer, the Merger or the Merger Agreement, and nothing in this Offer to Purchase or any action taken in connection herewith is intended as a waiver of that right. In the event that it is asserted that one or more takeover statutes apply to the Offer, the Merger or the Merger Agreement, and it is not determined by an appropriate court that such statute or statutes do not apply or are invalid as applied to the Offer, the Merger or the Merger Agreement, as applicable, Purchaser may be required to file certain documents with, or receive approvals from, the relevant state authorities, and Purchaser might be unable to accept for payment or purchase Shares tendered pursuant to the Offer or be delayed in continuing or consummating the Offer. In such case, Purchaser may not be obligated to accept for purchase, or pay for, any Shares tendered. See “The Tender Offer—Section 9. Conditions of the Offer.”

Appraisal Rights. No appraisal rights are available to the holders of Shares in connection with the Offer. However, if the Offer is successful and the Merger is consummated, stockholders of Theseus who: (i) did not tender their Shares in the Offer (or who had tendered but subsequently validly withdrawn such tender, and not otherwise waived their appraisal rights); (ii) otherwise comply with the applicable requirements and procedures of Section 262 of the DGCL; and (iii) do not thereafter withdraw their demand for appraisal of such Shares or otherwise lose their appraisal rights, in each case in accordance with the DGCL, will be entitled to demand appraisal of their Shares and receive in lieu of the consideration payable in the Merger a cash payment equal to the “fair value” of their Shares, as determined by the Delaware Court of Chancery, in accordance with Section 262 of the DGCL. If you choose to exercise your appraisal rights in connection with the Merger and you properly demand and perfect such rights in accordance with Section 262 of the DGCL, you may be entitled to payment for your Shares based on a judicial determination of the fair value of your Shares plus interest, if any, on the amount determined to be fair value.

The following discussion is not a complete statement of the law pertaining to appraisal rights under the DGCL and is qualified in its entirety by the full text of Section 262 of the DGCL, a copy of which may be accessed without subscription or cost at the following publicly available website: https://delcode.delaware.gov/title8/c001/sc09/index.html#262. All references in Section 262 of the DGCL and in this summary to a (i) “stockholder” are to the record holder of Shares unless otherwise expressly noted herein, (ii) “beneficial owner” are to a person who is the beneficial owner of Shares held either in voting trust or by a nominee on behalf of such person, and (iii) “person” are to an individual, corporation, partnership, unincorporated association or other entity. Stockholders and beneficial owners of Shares should carefully review the full text of Section 262 of the DGCL as well as the information discussed herein. Stockholders and beneficial owners of Shares should assume that Theseus will take no action to perfect any appraisal rights of any person.

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consideration payable in a sale transaction, such as the Offer and the Merger, is not an opinion as to, and does not otherwise address, fair value under the DGCL. Moreover, Parent and Theseus may argue in an appraisal proceeding that, for purposes of such proceeding, the “fair value” of such Shares is less than the Offer Price.

Any person who desires to exercise his, her or its appraisal rights should review carefully Section 262 of the DGCL and is urged to consult his, her or its legal advisor before electing or attempting to exercise such rights.

Under Section 262 of the DGCL, if a merger is approved under Section 251(h) of the DGCL, either a constituent corporation before the effective date of the merger, or the surviving corporation within 10 days thereafter, must notify each of the holders of any class or series of stock of such constituent corporation who are entitled to appraisal rights of the approval of the merger or consolidation and that appraisal rights are available for any or all shares of such class or series of stock of such constituent corporation, and shall include in such notice either a copy of Section 262 of the DGCL or information directing the stockholders to a publicly available electronic resource at which Section 262 of the DGCL may be accessed without subscription or cost. THE SCHEDULE 14D-9 CONSTITUTES THE FORMAL NOTICE OF APPRAISAL RIGHTS UNDER SECTION 262 OF THE DGCL. FAILURE TO FOLLOW THE STEPS REQUIRED BY SECTION 262 OF THE DGCL FOR EXERCISING AND PERFECTING APPRAISAL RIGHTS WILL RESULT IN THE LOSS OF SUCH RIGHTS.

As discussed in the Schedule 14D-9, stockholders and beneficial owners of Shares wishing to exercise the right to seek an appraisal of their Shares under Section 262 of the DGCL must do ALL of the following:

•

within the later of the consummation of the Offer (which will occur at the date and time of the acceptance for payment of Shares pursuant to and subject to the conditions of the Offer) and 20 days after the mailing of the Schedule 14D-9, deliver to Theseus at the address indicated in the Schedule 14D-9 a written demand for appraisal of their Shares, which demand must reasonably inform Theseus of the identity of the person making the demand and that the person is demanding appraisal and, in the case of a demand made by a beneficial owner of Shares, must also reasonably identify the holder of record of the Shares for which the demand is made, be accompanied by documentary evidence of such beneficial owner’s beneficial ownership of stock and a statement that such documentary evidence is a true and correct copy of what it purports to be, and provide an address at which such beneficial owner consents to receive notices given by the surviving corporation and to be set forth on the verified list required by subsection (f) of Section 262 of the DGCL;

•	not tender his, her or its Shares pursuant to the Offer (or, if tendered, validly and subsequently withdraw such Shares prior to the time Parent accepts properly tendered Shares for purchase); and

•	continuously hold of record or beneficially own, as applicable, the Shares from the date on which the written demand for appraisal is made through the Effective Time.

Any stockholder who sells Shares in the Offer will not be entitled to exercise appraisal rights with respect thereto but rather will receive the Offer Price, subject to the terms and conditions of the Merger Agreement, as well as the Offer to Purchase and related Letter of Transmittal, as applicable.

The preservation and exercise of appraisal rights require strict and timely adherence to the applicable provisions of Delaware law which will be set forth in their entirety in the Schedule 14D-9.

The information provided above is for informational purposes only with respect to your alternatives if the Merger is consummated. Any person who desires to exercise his, her or its appraisal rights should review carefully Section 262 of the DGCL and is urged to consult his, her or its legal advisor before electing or attempting to exercise such rights. The foregoing summary does not constitute any legal or other advice nor does it constitute a recommendation that Theseus stockholders or beneficial owners of Shares exercise appraisal rights under Section 262 of the DGCL.

If you tender your Shares into the Offer, you will not be entitled to exercise appraisal rights with respect to your Shares but, instead, subject to the conditions to the Offer, you will receive the Offer Price for your Shares.

“Going Private” Transactions. Rule 13e-3 under the Exchange Act is applicable to certain “going private” transactions and may under certain circumstances be applicable to the Merger. However, Rule 13e-3 will be inapplicable if: (i) the Shares are deregistered under the Exchange Act prior to the Merger or another business

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combination; or (ii) the Merger or other business combination is consummated within one year after the purchase of the Shares pursuant to the Offer and the amount paid per Share in the Merger or other business combination is at least equal to the amount paid per Share in the Offer. Neither Parent nor Purchaser believes that Rule 13e-3 will be applicable to the Merger.

Litigation. There have been no lawsuits filed against Theseus, the Theseus Board, Parent or Purchaser in connection with the Offer. Lawsuits may be filed against Theseus and the Theseus Board, and lawsuits may be filed against Parent and Purchaser, in connection with the Offer, the Merger and the related disclosures. Absent new or different allegations that are material, Parent and Purchaser will not, and understand that Theseus will not, necessarily announce such filings.

12.	FEES AND EXPENSES.

Parent has retained the Depositary and Paying Agent and the Information Agent in connection with the Offer. The Depositary and Paying Agent and the Information Agent will receive customary compensation, reimbursement for reasonable out-of-pocket expenses and indemnification against certain liabilities in connection with the Offer, including certain liabilities under the federal securities laws.

As part of the services included in such retention, the Information Agent may contact holders of Shares by personal interview, mail, electronic mail, telephone, telex, telegraph and other methods of electronic communication and may request brokers, dealers, commercial banks, trust companies and other nominees to forward the Offer materials to beneficial holders of Shares.

Except as set forth above, neither Parent nor Purchaser will pay any fees or commissions to any broker or dealer or other person for soliciting tenders of Shares pursuant to the Offer. Brokers, dealers, commercial banks and trust companies will upon request be reimbursed by us for customary mailing and handling expenses incurred by them in forwarding the offering material to their customers.

13.	MISCELLANEOUS.

The Offer is being made to all holders of the Shares. We are not aware of any jurisdiction in which the making of the Offer or the acceptance thereof would be prohibited by securities, “blue sky” or other valid laws of such jurisdiction. If we become aware of any U.S. state in which the making of the Offer or the acceptance of Shares pursuant thereto would not be in compliance with an administrative or judicial action taken pursuant to a U.S. state statute, we will make a good faith effort to comply with any such law. If, after such good faith effort, we cannot comply with any such law, the Offer will not be made to (nor will tenders be accepted from or on behalf of) the holders of Shares in such state. In any jurisdictions where applicable laws require the Offer to be made by a licensed broker or dealer, the Offer shall be deemed to be made on behalf of Purchaser by one or more registered brokers or dealers licensed under the laws of such jurisdiction to be designated by Purchaser.

Parent and Purchaser have filed with the SEC the Schedule TO (including exhibits) in accordance with the Exchange Act, furnishing certain additional information with respect to the Offer, and may file amendments thereto. The Schedule TO and any amendments thereto, including exhibits, may be examined and copies may be obtained from the SEC in the manner set forth in “The Tender Offer—Section 5. Certain Information Concerning Theseus.”

The Offer does not constitute a solicitation of proxies for any meeting of Theseus’ stockholders. Any solicitation of proxies which Purchaser or any of its affiliates might seek would be made only pursuant to separate proxy materials complying with the requirements of Section 14(a) of the Exchange Act.

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No person has been authorized to give any information or make any representation on behalf of Parent or the Purchaser not contained in this Offer to Purchase or in the Letter of Transmittal and, if given or made, such information or representation must not be relied upon as having been authorized. No broker, dealer, bank, trust company, fiduciary or other person shall be deemed to be an agent of Parent, Purchaser, the Depositary and Paying Agent or the Information Agent for the purpose of the Offer. Neither delivery of this Offer to Purchase nor any purchase pursuant to the Offer will, under any circumstances, create any implication that there has been no change in the affairs of Parent, Purchaser, Theseus or any of their respective subsidiaries since the date as of which information is furnished or the date of this Offer to Purchase.

			Concentra Merger Sub II, Inc.

			Concentra Biosciences, LLC

			Tang Capital Partners, LP

			January 9, 2024

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SCHEDULE A

INFORMATION CONCERNING MEMBERS OF THE BOARDS OF DIRECTORS AND

THE EXECUTIVE OFFICERS OF PURCHASER, PARENT AND THE GUARANTOR.

1.	Concentra Merger Sub II, Inc.

Concentra Merger Sub II, Inc. was incorporated for the purpose of consummating the Offer and effecting the Merger pursuant to the Merger Agreement. The following table sets forth information about the sole director and executive officers of Concentra Merger Sub, Inc. as of January 8, 2024.

Name, Position Country of Citizenship			Present Principal Occupation or Employment; Material Positions Held During the Past Five Years; Certain Other Information
Kevin Tang, Chairman and Chief Executive Officer Citizenship: United States			Mr. Tang serves as Chief Executive Officer of Concentra Biosciences, LLC and Chief Executive Officer and Chairman of Concentra Merger Sub II, Inc. Mr. Tang also serves as President of Tang Capital Management, LLC, a life sciences-focused investment company he founded in 2002. Since the company’s inception in 2013, he has served as the Chairman and Chief Executive Officer of Odonate, Inc. From 2014 to 2022, Mr. Tang served as Chairman of La Jolla Pharmaceutical Company. From 2009 to 2020, he served as a director of Heron Therapeutics, Inc. and, from 2012 to 2020, served as Chairman. From 2009 through its acquisition by Endo Pharmaceuticals, Inc. in 2010, Mr. Tang served as a director of Penwest Pharmaceuticals Co. In 2006, he co-founded Ardea Biosciences, Inc. and served as a director from inception through its acquisition by AstraZeneca PLC in 2012. From 2001 to 2008, Mr. Tang served as a director of Trimeris, Inc. From 1993 to 2001, he held various positions at Deutsche Banc Alex Brown, Inc., an investment banking firm, most recently serving as Managing Director and head of the firm’s Life Sciences research group. Mr. Tang received a B.S. degree from Duke University.

Michael Hearne, Chief Financial Officer Citizenship: United States			Mr. Hearne serves as Chief Financial Officer of Concentra Biosciences, LLC and Chief Financial Officer of Concentra Merger Sub II, Inc. Since 2015, he has served as Chief Financial Officer of Tang Capital Management, LLC, a life sciences-focused investment company. Since 2015, Mr. Hearne has also held various positions at Odonate, Inc., most recently serving as Chief Financial Officer since 2018. From 2020 to 2022, he served as Chief Financial Officer of La Jolla Pharmaceutical Company. From 2014 to 2015, he served as a partner at Weaver & Tidwell, LLP. Mr. Hearne started his career in public accounting at Coopers & Lybrand. Mr. Hearne received a B.S. degree in accounting and a masters of accountancy, taxation from Brigham Young University and is a Certified Public Accountant (inactive) in the state of California.

Ryan Cole, Chief Operating Officer Citizenship: United States			Mr. Cole serves as Chief Operating Officer of Concentra Biosciences, LLC and Chief Operating Officer of Concentra Merger Sub II, Inc. Since 2014, he has served in various positions at Tang Capital Management, LLC, a life sciences-focused investment company, most recently serving as Chief Operating Officer since 2022. From 2012 to 2014, Mr. Cole served as a Senior Financial Analyst of Mergers and Acquisitions at Thermo Fisher Scientific Inc. Mr. Cole started his career in public accounting at Ernst & Young, LLP. Mr. Cole received a B.A. degree in accounting and finance from Santa Clara University and is a Certified Public Accountant (inactive) in the state of California.

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Name, Position Country of Citizenship			Present Principal Occupation or Employment; Material Positions Held During the Past Five Years; Certain Other Information
Stew Kroll, Chief Development Officer Citizenship: United States			Mr. Kroll serves as Chief Development Officer of Concentra Biosciences, LLC and Chief Development Officer of Concentra Merger Sub II, Inc. Since 2016, he has served in various positions at Tang Capital Management, LLC, a life sciences-focused investment company, most recently serving as Managing Director since 2021. From 2017 to 2022, he served as Chief Development Officer of La Jolla Pharmaceutical Company. From 2016 to 2021, Mr. Kroll held various positions at Odonate, Inc., most recently serving as Chief Development Officer. From 2005 to 2016, Mr. Kroll held various positions at Threshold Pharmaceuticals, Inc., most recently serving as Chief Operating Officer. From 2000 to 2005, he served as Senior Director of Biostatistics at Corixa Corporation. From 1997 to 2000, Mr. Kroll held various positions at Coulter Pharmaceutical, Inc., most recently serving as Director of Biostatistics. Mr. Kroll received an M.A. degree and B.A. degree in statistics from the University of California, Berkeley.

Thomas Wei, Chief Business Officer Citizenship: United States			Mr. Wei serves as Chief Business Officer of Concentra Biosciences, LLC and Chief Business Officer of Concentra Merger Sub II, Inc. Since 2015, he has served as Managing Director of Tang Capital Management, LLC, a life sciences-focused investment company. From 2015 to 2021, Mr. Wei held various positions at Odonate, Inc., most recently serving as Chief Scientific Officer. From 2009 to 2015, he served as a Managing Director and biotechnology equity research analyst at Jefferies LLC. From 2003 to 2009, Mr. Wei was a biotechnology equity research analyst at Piper Jaffray, most recently serving as Managing Director. From 1998 to 2003, Mr. Wei was a biotechnology equity research analyst at Deutsche Bank AG and Adams, Harkness & Hill Inc. Mr. Wei received an A.B. degree in biochemical sciences from Harvard University and an M.B.A. degree from Oxford University.

The common business address and telephone number for the sole director and executive officers of Purchaser is as follows: c/o Concentra Merger Sub II, Inc., 4747 Executive Drive, Suite 210, San Diego, California 92121, Tel. (858) 281-5372.

2.	Concentra Biosciences, LLC

Concentra Biosciences, LLC’s principal business is currently to consummate the Offer and effect the Merger pursuant to the Merger Agreement, and to perform its obligations under the CVR Agreement following the Merger when Theseus is a wholly owned subsidiary of Parent as the surviving entity from the Merger. The following table sets forth information about the executive officers of Concentra Biosciences, LLC as of January 8, 2024.

Name, Position Country of Citizenship			Present Principal Occupation or Employment; Material Positions Held During the Past Five Years
Kevin Tang, Chief Executive Officer Citizenship: United States			Refer above.
Michael Hearne, Chief Financial Officer Citizenship: United States			Refer above.
Ryan Cole, Chief Operating Officer Citizenship: United States			Refer above.
Stew Kroll, Chief Development Officer Citizenship: United States			Refer above.
Thomas Wei, Chief Business Officer Citizenship: United States			Refer above.

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The common business address and telephone number for all the directors and executive officers of Parent is as follows: c/o Concentra Biosciences, LLC, 4747 Executive Drive, Suite 210, San Diego, California 92121, Tel: (858) 281-5372.

3.	Tang Capital Management, LLC

Tang Capital Management, LLC is the sole manager of Parent and general partner of TCP. The following table sets forth information about the executive officers of Tang Capital Management, LLC as of January 8, 2024.

Name, Position Country of Citizenship			Present Principal Occupation or Employment; Material Positions Held During the Past Five Years
Kevin Tang, President Citizenship: United States			Refer above.
Michael Hearne, Chief Financial Officer Citizenship: United States			Refer above.
Ryan Cole, Chief Operating Officer Citizenship: United States			Refer above.

The common business address and telephone number for TCM, Mr. Tang, Mr. Hearne and Mr. Cole is as follows: c/o Tang Capital Management, LLC, 4747 Executive Drive, Suite 210, San Diego, CA 92121, Tel. (858) 200-3830.

4.	Tang Capital Partners, LP

Tang Capital Partners, LP’s principal business is a life sciences-focused investment company. Tang Capital Management, LLC is the general partner of Tang Capital Partners, LP. The business address and telephone number for TCP is as follows: c/o Tang Capital Management, LLC, 4747 Executive Drive, Suite 210, San Diego, CA 92121, Tel. (858) 200-3830.

The Letter of Transmittal, certificates for Shares and any other required documents should be sent by each stockholder of Theseus or such stockholder’s broker, dealer, commercial bank, trust company or other nominee to the Depositary and Paying Agent as follows:

The Depositary and Paying Agent for the Offer is:

Broadridge Corporate Issuer Solutions, LLC

Mail or deliver the Letter of Transmittal, together with the certificate(s) (if any) representing your shares, to:

If delivering by mail:			If delivering by express mail, courier, or other expedited service:

Broadridge Corporate Issuer Solutions, LLC Attention: BCIS Re-Organization Dept. P.O. Box 1317 Brentwood, NY 11717-0718			Broadridge Corporate Issuer Solutions, LLC Attention: BCIS IWS 51 Mercedes Way Edgewood, NY 11717

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Other Information:

Questions or requests for assistance or additional copies of this Offer to Purchase, the Letter of Transmittal, and the Schedule TO may be directed to the Information Agent at its location and telephone numbers set forth below. Stockholders may also contact their broker, dealer, commercial bank or trust company for assistance concerning the Offer.

The Information Agent for the Offer is:

Morrow Sodali LLC

430 Park Avenue

14^th Floor

New York, NY 10022

You may call Morrow Sodali LLC, the Information Agent for the Offer, toll-free at (800) 662-5200 or email them at THRX@investor.morrowsodali.com. Banks and brokers may call collect at 203 658-9400.

Exhibit (a)(1)(B)

Letter of Transmittal

To Tender Shares of Common Stock

THESEUS PHARMACEUTICALS, INC.

a Delaware corporation

A Cash Amount per Share between $3.90 and $4.05, Consisting of a Base Price Per Share of $3.90 and

Within 180 Days of the Closing Date, as Described in the CVR Agreement

Pursuant to the Offer to Purchase

Dated January 9, 2024

CONCENTRA MERGER SUB II, INC.,

a wholly owned subsidiary of

CONCENTRA BIOSCIENCES, LLC

TANG CAPITAL PARTNERS, LP

TANG CAPITAL MANAGEMENT, LLC

THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE ONE MINUTE AFTER

11:59 P.M., EASTERN TIME, ON FEBRUARY 7, 2024 (THE “EXPIRATION DATE”),

UNLESS THE OFFER IS EXTENDED OR EARLIER TERMINATED.

The Depositary and Paying Agent for the Offer Is:

Broadridge Corporate Issuer Solutions, LLC

If delivering by hand, express mail, courier or other expedited service:			If delivering by mail:

Broadridge Corporate Issuer Solutions, LLC Attention: BCIS IWS 51 Mercedes Way Edgewood, NY 11717			Broadridge Corporate Issuer Solutions, LLC Attention: BCIS Re-Organization Dept. P.O. Box 1317 Brentwood, NY 11717-0718

DESCRIPTION OF SHARES SURRENDERED

*	Need not be completed by book-entry stockholders.

**	Unless otherwise indicated, it will be assumed that all shares above of common stock represented by certificates described above are being surrendered hereby.

Delivery of this Letter of Transmittal to an address other than as set forth above will not constitute a valid delivery to Broadridge Corporate Issuer Solutions, LLC (the “Depositary and Paying Agent”). You must sign this Letter of Transmittal in the appropriate space provided therefor below, with signature guaranteed, if required, and complete and sign the Internal Revenue Service (the “IRS”) Form W-9 included in this Letter of Transmittal, if the stockholder is a United States person. Stockholders who are not United States persons should submit a properly completed and signed IRS Form W-8BEN or IRS Form W-8BEN-E, as applicable, or other appropriate IRS Form W-8. Failure to provide the information on IRS Form W-9 or an appropriate IRS Form W-8, as applicable, may subject you to United States backup withholding on any payments made to you pursuant to the Offer (as defined below). The instructions set forth in this Letter of Transmittal should be read carefully before you tender any of your Shares (as defined below) into the Offer (as defined below).

The Offer is being made to all holders of the Shares. Purchaser is not aware of any jurisdiction in which the making of the Offer or the acceptance thereof would be prohibited by securities, “blue sky” or other valid laws or regulations of such jurisdiction. If Purchaser becomes aware of any U.S. state in which the making of the Offer or the acceptance of Shares pursuant thereto would not be in compliance with an administrative or judicial action taken pursuant to a U.S. state statute, Purchaser will make a good faith effort to comply with any such law or regulation. If, after such good faith effort, Purchaser cannot comply with any such law or regulation, the Offer will not be made to (nor will tenders be accepted from or on behalf of) the holders of Shares in such state. In any jurisdictions where applicable laws or regulations require the Offer to be made by a licensed broker or dealer, the Offer shall be deemed to be made on behalf of Purchaser by one or more registered brokers or dealers licensed under the laws or regulations of such jurisdiction to be designated by Purchaser.

This Letter of Transmittal is to be used by stockholders of Theseus Pharmaceuticals, Inc. (“Theseus”) if certificates (“Certificates”) for shares of common stock, par value $0.0001 per share, of Theseus (the “Shares”) are to be forwarded herewith or, unless an Agent’s Message (as defined in Section 3 of the Offer to Purchase) is utilized, if delivery of Shares is to be made by book-entry transfer to an account maintained by the Depositary and Paying Agent at The Depository Trust Company (“DTC”) (as described in Summary Term Sheet of the Offer to Purchase and pursuant to the procedures set forth in Section 3 thereof).

☐	CHECK HERE IF TENDERED SHARES ARE BEING DELIVERED HEREWITH.

☐	CHECK HERE IF YOU HAVE LOST YOUR CERTIFICATE(S) AND REQUIRE ASSISTANCE IN OBTAINING REPLACEMENT CERTIFICATE(S). BY CHECKING THIS BOX, YOU UNDERSTAND THAT YOU MUST CONTACT THE TRANSFER AGENT TO OBTAIN INSTRUCTIONS FOR REPLACING LOST CERTIFICATES. SEE INSTRUCTION 11.

☐	CHECK HERE IF TENDERED SHARES ARE BEING DELIVERED BY BOOK-ENTRY TRANSFER MADE TO AN ACCOUNT MAINTAINED BY THE DEPOSITARY AND PAYING AGENT WITH DTC AND COMPLETE THE FOLLOWING (NOTE THAT ONLY FINANCIAL INSTITUTIONS THAT ARE PARTICIPANTS IN THE SYSTEM OF DTC MAY DELIVER SHARES BY BOOK-ENTRY TRANSFER):

Name of Tendering Institution:

DTC Account

Number:

Transaction

Code Number:

NOTE: SIGNATURES MUST BE PROVIDED BELOW

PLEASE READ ACCOMPANYING INSTRUCTIONS CAREFULLY

Ladies and Gentlemen:

The undersigned hereby tenders to Concentra Merger Sub II, Inc. (“Purchaser”), a Delaware corporation, and a wholly owned subsidiary of Concentra Biosciences, LLC, a Delaware limited liability company (“Parent”), the above described shares of common stock, par value $0.0001 per share (the “Shares”), of Theseus Pharmaceuticals, Inc., a Delaware corporation (“Theseus”), pursuant to Purchaser’s offer to purchase each outstanding Share that is validly tendered and not validly withdrawn, for: (i) $3.90 per Share in cash (the “Base Price Per Share”), (ii) an additional amount of cash of up to $0.15 per Share (such amount as finally determined pursuant to the Agreement and Plan of Merger, dated as December 22, 2023, the “Additional Price Per Share” and together with the Base Price Per Share, the “Cash Amount”), and (iii) one non-transferable contractual contingent value right for each Share (each, a “CVR,” and each CVR together with the Cash Amount, the “Offer Price”), subject to the terms and conditions described in the Offer to Purchase, dated January 9, 2024 (together with any amendments or supplements thereto, the “Offer to Purchase”) and in this Letter of Transmittal (together with any amendments or supplements thereto, the “Letter of Transmittal” which, together with the Offer to Purchase, as each may be amended and supplemented from time to time, collectively constitute the “Offer”), receipt of which is hereby acknowledged.

Upon the terms and subject to the conditions of the Offer (and if the Offer is extended or amended, the terms of any such extension or amendment), and effective upon acceptance for payment of the Shares validly tendered herewith and not validly withdrawn on or prior to the Expiration Date in accordance with the terms of the Offer, the undersigned hereby sells, assigns and transfers to or upon the order of Purchaser all right, title and interest in and to all of the Shares that are being tendered hereby (and any and all dividends, distributions, rights, other Shares or other securities issued or issuable in respect thereof on or after the date hereof (collectively, “Distributions”)) and irrevocably constitutes and appoints Broadridge Corporate Issuer Solutions, LLC (the “Depositary and Paying Agent”) the true and lawful agent and attorney-in-fact of the undersigned with respect to such Shares (and any and all Distributions), with full power of substitution (such power of attorney being deemed to be an irrevocable power coupled with an interest in the Shares tendered by this Letter of Transmittal), to: (i) deliver Certificates for such Shares (and any and all Distributions) or transfer ownership of such Shares (and any and all Distributions) on the account books maintained by The Depository Trust Company (“DTC”) or otherwise held in book-entry form, together, in any such case, with all accompanying evidences of transfer and authenticity, to or upon the order of Purchaser; (ii) present such Shares (and any and all Distributions) for transfer on the books of Theseus; and (iii) receive all benefits and otherwise exercise all rights of beneficial ownership of such Shares (and any and all Distributions), all in accordance with the terms and subject to the conditions of the Offer.

By executing this Letter of Transmittal (or taking action resulting in the delivery of an Agent’s Message, as defined in Section 3 of the Offer to Purchase), the undersigned hereby irrevocably appoints Kevin Tang, the designee of Purchaser, the attorney-in-fact and proxy of the undersigned, with full power of substitution, to: (i) vote at any annual or special meeting of Theseus stockholders or any adjournment or postponement thereof or otherwise in such manner as such attorney-in-fact and proxy or his substitute shall in his, her or its sole discretion deem proper with respect to; (ii) execute any written consent concerning any matter as such attorney-in-fact and proxy or his substitute shall in his, her or its sole discretion deem proper with respect to; and (iii) otherwise act as such attorney-in-fact and proxy or his substitute shall in his, her or its sole discretion deem proper with respect to, all of the Shares (and any and all Distributions) tendered hereby and accepted for payment by Purchaser. This appointment will be effective if and when, and only to the extent that, Purchaser accepts such Shares tendered with this Letter of Transmittal for payment pursuant to the Offer. This power of attorney and proxy are irrevocable and are granted in consideration of the acceptance for payment of such Shares in accordance with the terms of the Offer. Such acceptance for payment shall, without further action, revoke any prior powers of attorney and proxies granted by the undersigned at any time with respect to such Shares (and any and all Distributions), and no subsequent powers of attorney, proxies, consents or revocations may be given by the undersigned with respect thereto (and, if given, will not be deemed effective). Purchaser reserves the right to require that, in order for the Shares to be deemed validly tendered, immediately upon Purchaser’s acceptance for payment of such Shares, Purchaser or its designees must be able to exercise full voting, consent and other rights with respect to such Shares (and any and all Distributions), including voting at any meeting of Theseus stockholders or executing a written consent concerning any matter.

The undersigned hereby represents and warrants that the undersigned has full power and authority to tender, sell, assign and transfer any and all of the Shares tendered hereby (and any and all Distributions) and that, when the same are accepted for payment by Purchaser, Purchaser will acquire good, marketable and unencumbered title to such Shares (and such Distributions), free and clear of all liens, restrictions, charges and encumbrances and the same will not be subject to any adverse claims. The undersigned hereby represents and warrants that the undersigned is the registered owner of the Shares, or the Certificate(s) have been endorsed to the undersigned in blank, or the undersigned is a participant in DTC whose name appears on a security position listing as the owner of the Shares. The undersigned will, upon request, execute and deliver any additional documents deemed by the Depositary and Paying Agent or Purchaser to be necessary or desirable to complete the sale, assignment and transfer of the Shares tendered hereby (and any and all Distributions). In addition, the undersigned shall remit and transfer promptly to the Depositary and Paying Agent for the account of Purchaser all Distributions in respect of any and all of the Shares tendered hereby, accompanied by appropriate documentation of transfer, and, pending such remittance and transfer or appropriate assurance thereof, Purchaser shall be entitled to all rights and privileges as owner of each such Distribution and may withhold the entire Offer Price of the Shares tendered hereby or deduct from such Offer Price the amount or value of such Distribution as determined by Purchaser in its sole discretion.

All authority conferred or agreed to be conferred pursuant to this Letter of Transmittal shall not be affected by, and shall survive the death or incapacity of the undersigned, and any obligation of the undersigned hereunder shall be binding upon the heirs, executors, administrators, personal representatives, trustees in bankruptcy, successors and assigns of the undersigned. Except as stated in the Offer to Purchase, this tender is irrevocable.

It is understood that the undersigned will not receive payment for the Shares unless and until the Shares are accepted for payment and until the Certificate(s) owned by the undersigned are received by the Depositary and Paying Agent at the address set forth above, together with such additional documents as the Depositary and Paying Agent may require, or, in the case of Shares held in book-entry form, ownership of Shares is validly transferred on the account books maintained by DTC, and until the same are processed for payment by the Depositary and Paying Agent.

The undersigned hereby acknowledges that delivery of any Certificate shall be effected, and risk of loss and title to such Certificate shall pass, only upon the proper delivery of such Certificate to the Depositary and Paying Agent.

The undersigned understands that the valid tender of Shares pursuant to any of the procedures described in the Offer to Purchase and in the instructions hereto will constitute the undersigned’s acceptance of the terms and conditions of the Offer. Purchaser’s acceptance of such Shares for payment will constitute a binding agreement between the undersigned and Purchaser upon the terms and subject to the conditions of the Offer (and if the Offer is extended or amended, the terms and conditions of such extension or amendment). The undersigned recognizes that under certain circumstances set forth in the Offer, Purchaser may not be required to accept for payment any Shares tendered hereby.

The undersigned understands that the CVRs will not be transferable except: (i) upon death of the holder by will or intestacy; (ii) pursuant to a court order; (iii) by operation of law (including by consolidation or merger) or without consideration in connection with the dissolution, liquidation or termination of any corporation, limited liability company, partnership or other entity; (iv) in the case of CVRs held in book-entry or other similar nominee form, from a nominee to a beneficial owner and, if applicable, through an intermediary, to the extent allowable by DTC; or (v) CVRs may be abandoned. The undersigned further understands that the CVRs will not have any voting or dividend rights, or accrue interest and will not represent any equity or ownership interests in the Purchaser, Parent or Theseus. The undersigned understands that the CVRs will be registered in the name of the undersigned.

Unless otherwise indicated under “Special Payment Instructions,” a check will be issued for the Cash Amount of all Shares purchased and, if appropriate, Certificates not tendered or accepted for payment in the name(s) of the registered holder(s) appearing above under “Description of Shares Tendered” will be returned. Similarly, unless otherwise indicated under “Special Delivery Instructions,” the check for the Cash Amount of all Shares purchased will be mailed and, if appropriate, any Certificates not tendered or not accepted for payment (and any accompanying documents, as appropriate) will be returned to the address(es) of the registered holder(s) appearing above under “Description of Shares Tendered.” In the event that the boxes entitled “Special Payment

Instructions” and “Special Delivery Instructions” are both completed, the check for the Cash Amount of all Shares purchased will be issued and, if appropriate, any Certificates not tendered or not accepted for payment (and any accompanying documents, as appropriate) will be returned in the name(s) of, and deliver such check and, if appropriate, return any Certificates (and any accompanying documents, as appropriate) to, the person(s) so indicated. Unless otherwise indicated herein in the box entitled “Special Payment Instructions,” any Shares tendered herewith that are not accepted for payment will be credited by book-entry transfer by crediting the account at DTC designated above. The undersigned recognizes that Purchaser has no obligation, pursuant to the “Special Payment Instructions,” to transfer any Shares from the name of the registered holder thereof if Purchaser does not accept for payment any of the Shares so tendered. Subject to the terms of the CVR Agreement, please make all payments regarding the CVRs as directed herein for payment of the cash consideration and enter in the CVR register to be maintained by the rights agent pursuant to the CVR Agreement the name(s) and address(es) appearing on the cover page of this Letter of Transmittal for each registered holder. The undersigned recognizes that Purchaser has no obligation, pursuant to the Special Payment Instructions, to transfer any Shares from the name(s) of the registered holder(s) thereof if Purchaser does not accept for payment any of the Shares so tendered.

SPECIAL PAYMENT INSTRUCTIONS (See Instructions 1, 5, 6 and 7) To be completed ONLY if the check for the Cash Amount for Shares accepted for payment and/or Certificates not tendered or not accepted for payment are to be issued in the name of someone other than the undersigned.			SPECIAL DELIVERY INSTRUCTIONS (See Instructions 1, 5, 6 and 7) To be completed ONLY if the check for the Cash Amount for Shares accepted for payment and/or Certificates evidencing Shares not tendered or not accepted are to be mailed to someone other than the undersigned or to the undersigned at an address other than that shown above.

Issue check and/or Certificates to:			Mail check and/or Certificates to:

Name: (Please Print)			Name: (Please Print)

Address:			Address:

(Include Zip Code)			(Include Zip Code)

(Taxpayer Identification No. (e.g., Social Security No.)) (Also complete, as appropriate, IRS Form W-9 included below)

IMPORTANT

STOCKHOLDER: YOU MUST SIGN BELOW

(U.S. Holders: Please complete and return the IRS Form W-9 included below)

(Non-U.S. Holders: Please obtain, complete and return appropriate IRS Form W-8)

(Signature(s) of Holder(s) of Shares)

Dated:

Name(s):

(Please Print)

Capacity (Full Title) (See Instruction 5):

Address:

(Include Zip Code)

Area Code and Telephone No.:

Tax Identification No. (e.g., Social Security No.) (See IRS Form W-9 included below):

(Must be signed by registered holder(s) exactly as name(s) appear(s) on Certificate(s) or on a security position listing or by person(s) authorized to become registered holder(s) by Certificates and documents transmitted herewith. If signature is by a trustee, executor, administrator, guardian, attorney-in-fact, agent, officer of a corporation or other person acting in a fiduciary or representative capacity, please set forth full title and see Instruction 5. For information concerning signature guarantees, see Instruction 1)

Guarantee of Signature(s)

(If Required—See Instructions)

[Place Stamp Here]
Authorized Signature:


Name:


Name of Firm:


Address:

(Include Zip Code)
Area Code and Telephone No.:

Dated: , 2024

INSTRUCTIONS

FORMING PART OF THE TERMS AND CONDITIONS OF THE OFFER

1. GUARANTEE OF SIGNATURES. No signature guarantee is required on this Letter of Transmittal: (a) if this Letter of Transmittal is signed by the registered holder(s) (which term, for purposes of this Instruction, includes any participant in DTC’s systems whose name appears on a security position listing as the owner of the Shares) of Shares tendered herewith, unless such registered holder has completed either the box entitled “Special Payment Instructions” or the box entitled “Special Delivery Instructions” on this Letter of Transmittal; or (b) if such Shares are tendered for the account of a financial institution (including most commercial banks, savings and loan associations and brokerage houses) that is a member in good standing of the Securities Transfer Agents Medallion Program or any other “eligible guarantor institution,” as such term is defined in Rule 17Ad-15 under the Securities Exchange Act of 1934, as amended (each, an “Eligible Institution”). In all other cases, including those referred to above, all signatures on this Letter of Transmittal must be guaranteed by an Eligible Institution. See Instruction 5.

2. REQUIREMENTS OF TENDER. No alternative, conditional or contingent tenders will be accepted. In order for Shares to be validly tendered pursuant to the Offer, one of the following procedures must be followed:

For Shares held as physical certificates, the Certificates representing tendered Shares, a properly completed and duly executed Letter of Transmittal, together with any required signature guarantees, and any other documents required by this Letter of Transmittal, must be received by the Depositary and Paying Agent at one of its addresses set forth on the front page of this Letter of Transmittal before the Expiration Date.

For Shares held in book-entry form, either a properly completed and duly executed Letter of Transmittal, together with any required signature guarantees, or an Agent’s Message in lieu of this Letter of Transmittal, and any other required documents, must be received by the Depositary and Paying Agent at the appropriate address set forth on the front page of this Letter of Transmittal, and such Shares must be delivered according to the book-entry transfer procedures (as set forth in Section 3 of the Offer to Purchase) and a timely confirmation of a book-entry transfer of Shares into the Depositary and Paying Agent’s account at DTC (a “Book-Entry Confirmation”) must be received by the Depositary and Paying Agent, in each case before the Expiration Date.

The method of delivery of Shares, Certificate(s), this Letter of Transmittal, and all other required documents, including delivery through DTC, is at the election and risk of the tendering stockholder. Shares will be deemed delivered (and the risk of loss of Certificates will pass) only when actually received by the Depositary and Paying Agent (including, in the case of a book-entry transfer, by Book-Entry Confirmation). If delivery is by mail, then registered mail with return receipt requested, properly insured, is recommended. In all cases, sufficient time should be allowed to ensure timely delivery.

No fractional Shares will be purchased. By executing this Letter of Transmittal, the tendering stockholder waives any right to receive any notice of the acceptance for payment of Shares.

3. INADEQUATE SPACE. If the space provided herein is inadequate, Certificate numbers, the number of Shares represented by such Certificates and/or the number of Shares tendered should be listed on a separate signed schedule attached hereto.

4. PARTIAL TENDERS (NOT APPLICABLE TO STOCKHOLDERS WHO TENDER BY BOOK-ENTRY TRANSFER). If fewer than all the Shares represented by any Certificate delivered to the Depositary and Paying Agent are to be tendered, fill in the number of Shares which are to be tendered in the box entitled “Total Number of Shares Tendered.” In such case, a new Certificate for the remainder of the Shares represented by the old Certificate will be sent to the person(s) signing this Letter of Transmittal, unless otherwise provided in the appropriate box on this Letter of Transmittal, as promptly as practicable following the expiration or termination of the Offer. All Shares represented by Certificates delivered to the Depositary and Paying Agent will be deemed to have been tendered unless otherwise indicated.

5. SIGNATURES ON LETTER OF TRANSMITTAL; STOCK POWERS AND ENDORSEMENTS.

(a) Exact Signatures. If this Letter of Transmittal is signed by the registered holder(s) of the Shares tendered hereby, the signature(s) must correspond with the name(s) as written on the face of the Certificates without alteration, enlargement or any change whatsoever.

(b) Joint Holders. If any of the Shares tendered hereby are held of record by two or more persons, all such persons must sign this Letter of Transmittal.

(c) Different Names on Certificates. If any of the Shares tendered hereby are registered in different names on different Certificates, it will be necessary to complete, sign and submit as many separate Letters of Transmittal as there are different registrations of Certificates.

(d) Endorsements. If this Letter of Transmittal is signed by the registered holder(s) of the Shares tendered hereby, no endorsements of Certificates or separate stock powers are required unless payment of the Offer Price (as defined in the Merger Agreement) is to be made, or Shares not tendered or not purchased are to be returned, in the name of any person other than the registered holder(s). Signatures on any such Certificates or stock powers must be guaranteed by an Eligible Institution.

(e) Stock Powers. If this Letter of Transmittal is signed by a person other than the registered holder(s) of the Shares tendered hereby, Certificates must be endorsed or accompanied by appropriate stock powers, in either case, signed exactly as the name(s) of the registered holder(s) appear(s) on the Certificates for such Shares. Signature(s) on any such Certificates or stock powers must be guaranteed by an Eligible Institution. See Instruction 1.

(f) Evidence of Fiduciary or Representative Capacity. If this Letter of Transmittal or any Certificate or stock power is signed by a trustee, executor, administrator, guardian, attorney-in-fact, officer of a corporation or other legal entity or other person acting in a fiduciary or representative capacity, such person should so indicate when signing, and proper evidence satisfactory to the Depositary and Paying Agent of the authority of such person so to act must be submitted. Proper evidence of authority includes a power of attorney, a letter of testamentary or a letter of appointment.

6. STOCK TRANSFER TAXES. Except as otherwise provided in this Instruction 6, Purchaser or any successor entity thereto will pay all stock transfer taxes with respect to the transfer and sale of any Shares pursuant to the Offer (for the avoidance of doubt, transfer taxes do not include U.S. federal income taxes or withholding taxes). If, however, consideration is to be paid to, or if Certificate(s) for Shares not tendered or not accepted for payment are to be registered in the name of, any person(s) other than the registered holder(s), or if tendered Certificate(s) for Share(s) are registered in the name of any person(s) other than the person(s) signing this Letter of Transmittal, Purchaser or any successor entity thereto will not be responsible for any stock transfer or similar taxes (whether imposed on the registered holder(s) or such other person(s) or otherwise) payable on account of the transfer to such other person(s) and no consideration shall be paid in respect of such Share(s) unless evidence satisfactory to Purchaser or any successor entity thereto of the payment of such taxes, or the inapplicability of such taxes, is submitted.

7. SPECIAL PAYMENT AND DELIVERY INSTRUCTIONS. If a check is to be issued for the Cash Amount of any Shares tendered by this Letter of Transmittal in the name of, and, if appropriate, Certificates for Shares not tendered or not accepted for payment are to be issued or returned to, any person(s) other than the signer of this Letter of Transmittal or if a check and, if appropriate, such Certificates are to be returned to any person(s) other than the person(s) signing this Letter of Transmittal or to an address other than that shown in this Letter of Transmittal, the appropriate boxes on this Letter of Transmittal must be completed.

8. TAX WITHHOLDING. Under U.S. federal income tax laws, the Depositary and Paying Agent may be required to withhold a portion of any payments made to certain stockholders pursuant to the Offer. To avoid such backup withholding, a tendering stockholder that is a United States person (as defined for in the instructions to IRS Form W-9, a “United States person”), and, if applicable, each other U.S. payee, is required to: (a) provide the Depositary and Paying Agent with a correct Taxpayer Identification Number (“TIN”) on IRS Form W-9, which is included herein, and to certify, under penalty of perjury, that such number is correct and that such stockholder or payee is not subject to backup withholding of U.S. federal income tax; or (b) otherwise establish a basis for exemption from backup withholding. Failure to provide the information on the IRS Form W-9 may subject the tendering stockholder or payee to backup withholding at the applicable rate (currently 24%), and such stockholder or payee may be subject to a penalty imposed by the IRS. See the enclosed IRS Form W-9 and the instructions thereto for additional information.

Certain stockholders or payees (including, among others, corporations) may not be subject to backup withholding. Exempt stockholders or payees that are United States persons should furnish their TIN, check the

appropriate box on the IRS Form W-9 and sign, date and return the IRS Form W-9 to the Depositary and Paying Agent in order to avoid backup withholding. A stockholder or other payee that is not a United States person establish an exemption from backup withholding: (a) by providing the Depositary and Paying Agent with a properly completed IRS Form W-8BEN or IRS Form W-8BEN-E, as applicable, or other appropriate IRS Form W-8, signed under penalties of perjury, attesting to such stockholder’s or payee’s foreign status; or (b) by otherwise establishing an exemption. An appropriate IRS Form W-8 may be obtained from the Depositary and Paying Agent or the IRS website (www.irs.gov). The Depositary and Paying Agent may withhold tax at a 30% rate (subject to certain exceptions) on payments made to non-U.S. stockholders pursuant to the Offer, unless the Depositary and Paying Agent determines that a reduced rate under an applicable income tax treaty or exemption from withholding is applicable. See “The Tender Offer—Section 3. Procedures for Tendering Shares” and “Special Factors—Section 6. Certain U.S. Federal Income Tax Consequences of the Offer and the Merger” of the Offer to Purchase.

Backup withholding is not an additional tax. Rather, the U.S. federal income tax liability of persons subject to backup withholding will be reduced by the amount of tax withheld. If backup withholding results in an overpayment of taxes, a refund or credit may be obtained from the IRS if eligibility is established and appropriate procedure is followed. Stockholders are urged to consult their tax advisors regarding the application of U.S. federal income tax withholding, including eligibility for a withholding tax reduction or exemption, and the IRS refund procedure.

9. IRREGULARITIES. All questions as to the validity, form, eligibility (including time of receipt) and acceptance for payment of any tender of Shares will be determined by Purchaser, in its sole discretion, which determination shall be final and binding on all parties. However, stockholders may challenge Purchaser’s determinations in a court of competent jurisdiction. Purchaser reserves the absolute right to reject any and all tenders determined by it not to be in proper form or the acceptance for payment of which may, in the opinion of its counsel, be unlawful. Purchaser also reserves the absolute right to waive any defect or irregularity in the tender of any Shares of any particular stockholder, whether or not similar defects or irregularities are waived in the case of other stockholders. No tender of Shares will be deemed to have been validly made until all defects and irregularities have been waived or cured within such time as Purchaser shall determine. None of Parent, Purchaser, the Depositary and Paying Agent, the Information Agent or any other person will be under any duty to give notice of any defects or irregularities in tenders or incur any liability for failure to give any such notice. Purchaser’s interpretation of the terms and conditions of the Offer (including the Letter of Transmittal and the instructions thereto) will be final and binding.

10. QUESTIONS AND REQUESTS FOR ADDITIONAL COPIES. The Information Agent may be contacted at the address and telephone number set forth on the last page of this Letter of Transmittal for questions and/or requests for additional copies of the Offer to Purchase, this Letter of Transmittal and other tender offer materials. You may also contact your broker, dealer, commercial bank, trust company or other nominee for assistance. Such copies will be furnished promptly at Purchaser’s expense.

11. LOST, STOLEN DESTROYED OR MUTILATED CERTIFICATES. If any Certificate has been lost, stolen, destroyed or mutilated, the stockholder should promptly notify the Transfer Agent toll-free at [1-800-546-5141]. The stockholder will then be instructed as to the steps that must be taken in order to replace such Certificates. You may be required to post a bond to secure against the risk that the Certificate(s) may be subsequently recirculated. This Letter of Transmittal and related documents cannot be processed until the procedures for replacing lost, destroyed or stolen certificates have been followed. You are urged to contact the Transfer Agent immediately in order to receive further instructions and for a determination of whether you will need to post a bond and to permit timely processing of this documentation. This Letter of Transmittal and related documents cannot be processed until the procedures for replacing lost, destroyed, mutilated or stolen Certificates have been followed.

Certificates evidencing tendered Shares, or a Book-Entry Confirmation into the Depositary and Paying Agent’s account at DTC, as well as this Letter of Transmittal, properly completed and duly executed, with any required signature guarantees, or an Agent’s Message (if utilized in lieu of this Letter of Transmittal in connection with a book-entry transfer), and any other documents required by this Letter of Transmittal, must be received before the Expiration Date.

IMPORTANT TAX INFORMATION

Under federal income tax law, a stockholder who is a U.S. person (as defined in the instructions to IRS Form W-9) surrendering Company Shares must, unless an exemption applies, provide the Depositary (as payer) with the stockholder’s correct TIN on IRS Form W-9, a copy of which is included in this Letter of Transmittal. If the stockholder is an individual, then the stockholder’s TIN is generally such stockholder’s Social Security number. If the correct TIN is not provided, then the stockholder may be subject to a penalty imposed by the IRS and payments of cash to the stockholder (or other payee) pursuant to the Offer may be subject to U.S. federal backup withholding (currently imposed at a rate of 24%).

Certain stockholders (including, among others, certain corporations and certain foreign individuals and entities) may not be subject to backup withholding and reporting requirements. In order for an exempt stockholder who is not a U.S. person (as defined in the instructions to IRS Form W-9) to avoid backup withholding, such person should complete, sign and submit an appropriate IRS Form W-8 signed under penalties of perjury, attesting to his, her or its exempt status. IRS Forms W-8 can be obtained from the Depositary, or from the IRS website at: http://www.irs.gov/w8. Such stockholders should consult a tax advisor to determine which version of IRS Form W-8 is appropriate. Exempt stockholders who are U.S. persons should furnish their TIN, check the “Exempt payee” box on the IRS Form W-9 and sign, date and return the IRS Form W-9 to the Depositary in order to avoid erroneous backup withholding. See the instructions enclosed with the IRS Form W-9 included in this Letter of Transmittal for additional instructions.

If backup withholding applies, the Depositary is required to withhold and pay over to the IRS a portion of any payment made to a stockholder. Backup withholding is not an additional tax. Rather, the federal income tax liability of persons subject to backup withholding may be reduced by the amount of tax withheld provided the required information is timely provided to the IRS. If backup withholding results in an overpayment of taxes, a refund may be obtained from the IRS provided the required information is timely provided to the IRS.

Purpose of IRS Form W-9

To prevent backup withholding on payments that are made to a stockholder with respect to Company Shares purchased pursuant to the Offer, the stockholder is required to notify the Depositary of the stockholder’s correct TIN by completing the IRS Form W-9 included in this Letter of Transmittal certifying that (1) the TIN provided on the IRS Form W-9 is correct (or that such stockholder is awaiting a TIN), (2) the stockholder is not subject to backup withholding because (i) the stockholder is exempt from backup withholding, (ii) the stockholder has not been notified by the IRS that the stockholder is subject to backup withholding as a result of a failure to report all interest and dividends or (iii) the IRS has notified the stockholder that the stockholder is no longer subject to backup withholding, and (3) the stockholder is a U.S. person (as defined in the instructions to IRS Form W-9).

What Number to Give the Depositary

The tendering stockholder is required to give the Depositary the TIN, generally the Social Security number or employer identification number, of the record holder of all Company Shares tendered hereby. If such Company Shares are in more than one name or are not in the name of the actual owner, consult the instructions enclosed with the IRS Form W-9 included in this Letter of Transmittal for additional guidance on which number to report. If the tendering stockholder has not been issued a TIN and has applied for a number or intends to apply for a number in the near future, such stockholder should write “Applied For” in the space for the TIN on the IRS Form W-9, sign and date the IRS Form W-9 and sign and date the Certificate of Awaiting Taxpayer Identification Number below. If the tendering stockholder writes “Applied For” in the space for the TIN and the Depositary is not provided with a TIN by the time of payment, the Depositary will withhold a portion of all payments of the purchase price, which will be refunded if a TIN is provided to the Depositary within sixty (60) days of the Depositary’s receipt of the Certificate of Awaiting Taxpayer Identification Number. If the Depositary is provided with an incorrect TIN in connection with such payments, then the stockholder may be subject to a penalty imposed by the IRS.

NOTE: FAILURE TO COMPLETE AND RETURN THE IRS FORM W-9 INCLUDED IN THIS LETTER OF TRANSMITTAL MAY RESULT IN BACKUP WITHHOLDING OF A PORTION OF ANY PAYMENTS MADE TO YOU PURSUANT TO THE OFFER. PLEASE REVIEW THE INSTRUCTIONS ENCLOSED WITH THE IRS FORM W-9 INCLUDED IN THIS LETTER OF TRANSMITTAL FOR ADDITIONAL DETAILS. YOU MUST COMPLETE THE FOLLOWING CERTIFICATE IF YOU WROTE “APPLIED FOR” IN THE SPACE FOR THE TIN ON THE IRS FORM W-9.

CERTIFICATE OF AWAITING TAXPAYER IDENTIFICATION NUMBER
	I certify under penalties of perjury that a taxpayer identification number has not been issued to me, and either (1) I have mailed or delivered an application to receive a taxpayer identification number to the appropriate IRS Center or Social Security Administration Office, or (2) I intend to mail or deliver an application in the near future. I understand that if I do not provide a taxpayer identification number by the time of payment, a portion of all reportable payments made to me will be withheld, but that such amounts will be refunded to me if I then provide a Taxpayer Identification Number within sixty (60) days.
	Signature	Date

The Depositary and Paying Agent for the Offer Is:

Broadridge Corporate Issuer Solutions, LLC

If delivering by hand, express mail, courier or other expedited service:			If delivering by mail:

Broadridge Corporate Issuer Solutions, LLC Attention: BCIS IWS 51 Mercedes Way Edgewood, NY 11717			Broadridge Corporate Issuer Solutions, LLC Attention: BCIS Re-Organization Dept. P.O. Box 1317 Brentwood, NY 11717-0718

Morrow Sodali LLC (the “Information Agent”) may be contacted at its address and telephone number listed below for questions and/or requests for additional copies of the Offer to Purchase, this Letter of Transmittal and other tender offer materials. You may also contact your broker, dealer, commercial bank, trust company or other nominee for assistance. Such copies will be furnished promptly at Purchaser’s expense.

The Information Agent for the Offer is:

Morrow Sodali LLC

430 Park Avenue

14^th Floor

New York, NY 10022

Banks and Brokers Call: (203) 658-9400

Stockholders Call Toll Free: (800) 662-5200

E-mail: THRX@investor.morrowsodali.com

Exhibit (a)(1)(C)

Offer to Purchase

All Outstanding Shares of Common Stock

THESEUS PHARMACEUTICALS, INC.

A Delaware corporation

A Cash Amount per Share between $3.90 and $4.05, Consisting of a Base Price Per Share of $3.90 and

Within 180 Days of the Closing Date, as Described in the CVR Agreement

Pursuant to the Offer to Purchase

Dated January 9, 2024

CONCENTRA MERGER SUB II, INC.

a wholly owned subsidiary of

CONCENTRA BIOSCIENCES, LLC

TANG CAPITAL PARTNERS, LP

TANG CAPITAL MANAGEMENT, LLC

THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE ONE MINUTE AFTER 11:59 P.M.

EASTERN TIME ON FEBRUARY 7, 2024, UNLESS THE OFFER IS EXTENDED

OR EARLIER TERMINATED.

January 9, 2024

To Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees:

We have been engaged by Concentra Merger Sub II, Inc., a Delaware corporation (“Purchaser”) and a wholly owned subsidiary of Concentra Biosciences, LLC, a Delaware limited liability company (“Parent”), to act as Information Agent in connection with Purchaser’s offer to purchase all of the outstanding shares of common stock, par value $0.0001 per share (the “Shares”), of Theseus Pharmaceuticals, Inc., a Delaware corporation (“Theseus”), for: (i) $3.90 per Share in cash, (ii) an additional amount of cash of up to $0.15 per Share (such amount as finally determined pursuant to the Agreement and Plan of Merger, dated as of December 22, 2023 (together with any amendments or supplements thereto, the “Merger Agreement”), among Theseus, Parent and Purchaser) and (iii) one non-transferable contractual contingent value right for each Share (each, a “CVR”), all upon the terms and subject to the conditions described in the Offer to Purchase (together with any amendments or supplements thereto, the “Offer to Purchase”) and in the related Letter of Transmittal (together with any amendments or supplements thereto, the “Letter of Transmittal” and, together with the Offer to Purchase, the “Offer”) enclosed herewith. Please furnish copies of the enclosed materials to those of your clients for whom you hold Shares registered in your name or in the name of your nominee. After careful consideration, the Theseus board of directors (the “Theseus Board”) have duly and unanimously: (i) determined that the terms of Offer, the Merger and the other transactions contemplated by the Merger Agreement and the CVR Agreement (collectively, the “Transactions”) are fair to and in the best interests of Theseus and the Theseus’ stockholders, (ii) approved and declared advisable the Merger and the execution, delivery and performance by Theseus of the Merger Agreement and the consummation of the Transactions, (iii) resolved that the Merger Agreement and the Merger shall be governed by and effected under Section 251(h) of the DGCL and that the Merger shall be consummated as soon as practicable following the Offer Closing Time (as defined in the Offer to Purchase), and (iv) resolved to recommend that Theseus’ stockholders accept the Offer and tender their Shares pursuant to the Offer, which resolutions shall not be subsequently rescinded, modified or withdrawn in any way, except in connection with a Superior Company Proposal (as such term is used in the Merger Agreement).

Concurrently with the execution of the Merger Agreement, and as a condition and inducement to Theseus’ willingness to enter into the Merger Agreement and the CVR Agreement (as defined in the Offer to Purchase), Tang Capital Partners, LP, a Delaware limited partnership (“TCP”) (“Guarantor”) and sole member of Parent, delivered to Theseus a duly executed limited guaranty (the “Limited Guaranty”), dated as of the date of the Merger Agreement, in favor of Theseus, in respect of certain obligations of Parent and Purchaser under the Merger Agreement and the CVR Agreement. Certain obligations under the Limited Guaranty are subject to a cap of $177,614,912, plus certain enforcement costs, under the Merger Agreement and an amount equivalent to the CVR Proceeds (as defined in the Offer to Purchase), plus certain enforcement costs, under the CVR Agreement. Tang Capital Management, LLC, a Delaware limited liability company (“TCM”), is the sole manager of Parent and the general partner of TCP. Accordingly, TCP and TCM are considered co-offerors in the Offer.

The Offer is not subject to any financing conditions. Certain conditions to the Offer are described in Section 13 of the Offer to Purchase.

For your information and for forwarding to your clients for whom you hold Shares registered in your name or in the name of your nominee, we are enclosing the following documents:

1.	The Offer to Purchase;

2.	The Letter of Transmittal for your use in accepting the Offer and tendering Shares and for the information of your clients, together with the included Internal Revenue Service Form W-9;

3.	A form of letter which may be sent to your clients for whose accounts you hold Shares registered in your name or in the name of your nominee, with space provided for obtaining such clients’ instructions with regard to the Offer; and

4.	A return envelope addressed to the Broadridge Corporate Issuer Solutions, LLC (the “Depositary and Paying Agent”) for your use only.

Your prompt action is requested. We urge you to contact your clients as promptly as possible. Please note that the Offer and withdrawal rights will expire one minute after 11:59 p.m., Eastern time, on February 7, 2024, unless the Offer is extended or earlier terminated.

For Shares to be properly tendered pursuant to the Offer, the share certificates (if any) or confirmation of receipt of such Shares under the procedure for book-entry transfer through The Depository Trust Company (“DTC”), together with a properly completed and duly executed Letter of Transmittal, including any required signature guarantees, or, in the case of book-entry transfer, either such Letter of Transmittal or an Agent’s Message (as defined in Section 3 of the Offer to Purchase) in lieu of such Letter of Transmittal, and any other documents required in the Letter of Transmittal, must be timely received by the Depositary and Paying Agent, all in accordance with the Offer to Purchase and the Letter of Transmittal.

Purchaser will not pay any fees or commissions to any broker or dealer or other person (other than the Depositary and Paying Agent and the Information Agent as described in the Offer to Purchase) for soliciting tenders of Shares pursuant to the Offer. Purchaser will, however, upon request, reimburse brokers, dealers, commercial banks and trust companies for reasonable and necessary costs and expenses incurred by them in forwarding materials to their customers. The Surviving Corporation (as defined in the Offer to Purchase) will pay all stock transfer taxes applicable to its purchase of Shares pursuant to the Offer, subject to Instruction 6 of the Letter of Transmittal.

Any inquiries you may have with respect to the Offer should be addressed to, and additional copies of the enclosed materials may be obtained from, the undersigned at the addresses and telephone numbers set forth on the back cover of the Offer to Purchase.

Very truly yours,

Broadridge Corporate Issuer Solutions, LLC

Nothing contained herein or in the enclosed documents shall render you the agent of the Purchaser, the Information Agent or the Depositary and Paying Agent or any affiliate of any of them or authorize you or any other person to use any document or make any statement on behalf of any of them in connection with the Offer other than the enclosed documents and the statements contained therein.

The Information Agent for the Offer is:

Morrow Sodali LLC

430 Park Avenue

14^th Floor

New York, NY 10022

Banks and Brokers Call: (203) 658-9400

Stockholders Call Toll Free: (800) 662-5200

E-mail: THRX@investor.morrowsodali.com

Exhibit (a)(1)(D)

Offer to Purchase

All Outstanding Shares of Common Stock

THESEUS PHARMACEUTICALS, INC.

A Cash Amount per Share between $3.90 and $4.05, Consisting of a Base Price Per Share of $3.90 and

Within 180 Days of the Closing Date, as Described in the CVR Agreement

CONCENTRA MERGER SUB II, INC.

a wholly owned subsidiary of

CONCENTRA BIOSCIENCES, LLC

TANG CAPITAL PARTNERS, LP

TANG CAPITAL MANAGEMENT, LLC

THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE ONE MINUTE AFTER 11:59 P.M.

EASTERN TIME ON FEBRUARY 7, 2024, UNLESS THE OFFER IS EXTENDED

OR EARLIER TERMINATED.

January 9, 2024

To Our Clients:

Enclosed for your consideration are the Offer to Purchase, dated January 9, 2024 (together with any amendments or supplements thereto, the “Offer to Purchase”), and the related Letter of Transmittal (together with any amendments or supplements thereto, the “Letter of Transmittal” and, together with the Offer to Purchase, the “Offer”) in connection with the offer by Concentra Merger Sub II, Inc., a Delaware corporation (“Purchaser”) and a wholly owned subsidiary of Concentra Biosciences, LLC, a Delaware limited liability company (“Parent”), to purchase, subject to certain conditions, all of the outstanding shares of common stock, par value $0.0001 per share (the “Shares”), of Theseus Pharmaceuticals, Inc., a Delaware corporation (“Theseus”), for: (i) $3.90 per Share in cash (the “Base Price Per Share”), (ii) an additional amount of cash of up to $0.15 per Share (such amount as finally determined pursuant to the Merger Agreement (as defined below), the “Additional Price Per Share” and together with the Base Price Per Share, the “Cash Amount”), and (iii) one non-transferable contractual contingent value right for each Share, all upon the terms and subject to the conditions described in the Offer to Purchase and the Letter of Transmittal.

Also enclosed is Theseus’ Solicitation/Recommendation Statement on Schedule 14D-9.

We or our nominees are the holder of record of Shares held for your account. A tender of such Shares can be made only by us as the holder of record and pursuant to your instructions.

The Letter of Transmittal accompanying this letter is furnished to you for your information only and cannot be used by you to tender Shares held by us for your account.

We request instructions as to whether you wish us to tender any or all of the Shares held by us for your account, upon the terms and subject to the conditions set forth in the enclosed Offer to Purchase and the Letter of Transmittal.

Please note carefully the following:

The Offer Price for the Offer is (i) $3.90 per Share in cash, (ii) an additional amount of cash of up to $0.15 per Share (such amount as finally determined pursuant to the Merger Agreement) in cash, and (iii) one non-transferable contractual contingent value right for each Share, in each case, to be paid net to you of any applicable tax withholding and without interest.

2.	The Offer is being made for all outstanding Shares.

Concurrently with the execution of the Merger Agreement, and as a condition and inducement to Theseus’ willingness to enter into the Merger Agreement, Tang Capital Partners, LP, a Delaware limited partnership (“TCP”) (“Guarantor”) and sole member of Parent, delivered to Theseus a duly executed limited guaranty (the “Limited Guaranty”), dated as of the date of the Merger Agreement, in favor of Theseus, in respect of certain obligations of Parent and Purchaser under the Merger Agreement and the CVR Agreement. Certain obligations under the Limited Guaranty are subject to a cap of $177,614,912, plus certain enforcement costs, under the Merger Agreement and an amount equivalent to the CVR Proceeds (as defined in the CVR Agreement), plus certain enforcement costs, under the CVR Agreement. Tang Capital Management, LLC, a Delaware limited liability company (“TCM”), is the sole manager of Parent and the general partner of TCP. Accordingly, TCP and TCM are considered co-offerors in the Offer.

5.	No appraisal rights are available to the holders of Shares in connection with the Offer, and stockholders who tender their Shares in the Offer will not have appraisal rights in connection with the Merger.

However, if Purchaser purchases Shares in the Offer and the Merger is consummated, holders of Shares outstanding as of immediately prior to the Effective Time who: (i) did not tender their Shares in the Offer (or, if tendered, validly and subsequently withdrew such Shares prior to the time Parent accepts properly tendered Shares for purchase); (ii) otherwise comply with the applicable procedures under Section 262 of the DGCL; and (iii) do not thereafter withdraw their demand for appraisal of such Shares or otherwise fail to prefect or lose their appraisal rights, in each case in accordance with the DGCL, will be entitled to demand appraisal of their Shares and receive in lieu of the consideration payable in the Merger a cash payment equal to the “fair value” of their Shares, as determined by the Delaware Court of Chancery, in accordance with Section 262 of the DGCL plus interest, if any, on the amount determined to be the fair value.

After careful consideration, the Theseus board of directors (the “Theseus Board”) has duly and unanimously: (i) determined that the terms of Offer, the Merger and the other transactions contemplated by the Merger Agreement and the CVR Agreement (collectively, the “Transactions”) are fair to and in the best interests of Theseus and the Theseus’ stockholders, and (ii) approved and declared advisable the Merger and the execution, delivery and performance by Theseus of the Merger Agreement and the consummation of the Transactions, (iii) resolved that the Merger Agreement and the Merger shall be governed by and effected under Section 251(h) of the DGCL, assuming the conditions thereto are met, and that the Merger shall be consummated as soon as practicable following the Offer Closing Time (as defined in the Merger Agreement), and (iv) resolved to recommend that Theseus’ stockholders accept the Offer and tender their Shares pursuant to the Offer, which resolutions shall not be subsequently rescinded, modified or withdrawn in any way, except in connection with a Superior Company Proposal (as such term is used in the Merger Agreement).

7.	The Offer and withdrawal rights will expire one minute after 11:59 p.m., Eastern time, on February 7, 2024, unless the Offer is extended or earlier terminated by Purchaser.

8.	The Offer is subject to certain conditions described in Section 9 of the Offer to Purchase.

9.	Any transfer taxes applicable to the sale of Shares to Purchaser pursuant to the Offer will be paid by the Surviving Corporation (as defined in the Offer to Purchase), except as otherwise provided in the Letter of Transmittal.

If you wish to have us tender any or all of your Shares, then please so instruct us by completing, executing, detaching and returning to us the Instruction Form on the detachable part hereof. An envelope to return your instructions to us is enclosed. If you authorize tender of your Shares, then all such Shares will be tendered unless otherwise specified on the Instruction Form.

Your prompt action is requested. Your Instruction Form should be forwarded to us in ample time to permit us to submit the tender on your behalf before the expiration of the Offer.

The Offer is not being made to, nor will tenders be accepted from or on behalf of, holders of Shares in any jurisdiction in which the making of the Offer or acceptance thereof would not be in compliance with the laws of such jurisdiction, and Purchaser is not aware of any jurisdiction in which the making of the Offer or the tender of Shares in connection therewith would not be in compliance with the laws of such jurisdiction. If Purchaser becomes aware of any jurisdiction in which the making of the Offer would not be in compliance with applicable law, Purchaser will make a good faith effort to comply with any such law. If, after such good faith effort, Purchaser cannot comply with any such law, the Offer will not be made to (nor will tenders be accepted from or on behalf of) the holders of Shares residing in such jurisdiction. In those jurisdictions where applicable laws require that the Offer be made by a licensed broker or dealer, the Offer will be deemed to be made on behalf of Purchaser by one or more registered brokers or dealers licensed under the laws of such jurisdiction to be designated by Purchaser.

INSTRUCTION FORM

With Respect to the Offer to Purchase for Cash

All Outstanding Shares of Common Stock

THESEUS PHARMACEUTICALS, INC.

A Cash Amount per Share between $3.90 and $4.05, Consisting of a Base Price Per Share of $3.90 and

Within 180 Days of the Closing Date, as Described in the CVR Agreement

CONCENTRA MERGER SUB II, INC.

a wholly owned subsidiary of

CONCENTRA BIOSCIENCES, LLC

TANG CAPITAL PARTNERS, LP

TANG CAPITAL MANAGEMENT, LLC

The undersigned acknowledge(s) receipt of your letter and the enclosed Offer to Purchase, dated January 9, 2024 (together with any amendments or supplements thereto, the “Offer to Purchase”), and the related Letter of Transmittal (together with any amendments or supplements thereto, the “Letter of Transmittal” and, together with the Offer to Purchase, the “Offer”), in connection with the offer by Concentra Merger Sub II, Inc., a Delaware corporation (“Purchaser”) and a wholly owned subsidiary of Concentra Biosciences, LLC, a Delaware limited liability company (“Parent”), to purchase all of the outstanding shares of common stock, par value $0.0001 per share (the “Shares”), of Theseus Pharmaceuticals, Inc., a Delaware corporation (“Theseus”), for: (i) $3.90 per Share in cash (the “Base Price Per Share”), (ii) an additional amount of cash of up to $0.15 per Share (such amount as finally determined pursuant to the Agreement and Plan of Merger, dated as of December 22, 2023, among Theseus, Parent and Purchaser (together with any amendments or supplements thereto, the “Merger Agreement”), the “Additional Price Per Share” and together with the Base Price Per Share, the “Cash Amount”), and (iii) one non-transferable contractual contingent value right per Share (each, a “CVR,” and each CVR together with the Cash Amount, the “Offer Price”), all upon the terms and subject to the conditions described in the Offer to Purchase and the Letter of Transmittal. The Offer Price will be paid net of any applicable tax withholding and without interest. The undersigned hereby instruct(s) you to tender to Purchaser the number of Shares indicated below or, if no number is indicated, all Shares held by you for the account of the undersigned, upon the terms and subject to the conditions set forth in the Offer.

Concurrently with the execution of the Merger Agreement, and as a condition and inducement to Theseus’ willingness to enter into the Merger Agreement and the CVR Agreement (as defined in the Offer to Purchase), Tang Capital Partners, LP, a Delaware limited partnership (“TCP”) (“Guarantor”) and sole member of Parent, delivered to Theseus a duly executed limited guaranty (the “Limited Guaranty”), dated as of the date of the Merger Agreement, in favor of Theseus, in respect of certain obligations of Parent and Purchaser under the Merger Agreement and the CVR Agreement. Certain obligations under the Limited Guaranty are subject to a cap of $177,614,912, plus certain enforcement costs, under the Merger Agreement and an amount equivalent to the CVR Proceeds (as defined in the CVR Agreement), plus certain enforcement costs, under the CVR Agreement. Tang Capital Management, LLC, a Delaware limited liability company (“TCM”), is the sole manager of Parent and the general partner of TCP. Accordingly, TCP and TCM are considered co-offerors in the Offer.

The undersigned understands and acknowledges that all questions as to validity, form and eligibility of the surrender of any certificate representing Shares submitted on the undersigned’s behalf to Broadridge Corporate Issuer Solutions, LLC (the “Paying and Depositary Agent”) will be determined by Purchaser (which may delegate power in whole or in part to the Paying and Depositary Agent) and such determination shall be final and binding.

ACCOUNT NUMBER:

NUMBER OF SHARES BEING TENDERED HEREBY: SHARES*

The method of delivery of this document is at the election and risk of the tendering stockholder. If delivery is by mail, then registered mail with return receipt requested, properly insured, is recommended. In all cases, sufficient time should be allowed to ensure timely delivery.

*	Unless otherwise indicated, it will be assumed that all Shares held by us for your account are to be tendered.

Dated: , 2024

(Signature(s)) (Please Print Name(s))
Address:

Include Zip Code

Area Code and Telephone No.

Taxpayer Identification or Social Security No.

Exhibit (d)(2)

PERSONAL AND CONFIDENTIAL

November 30, 2023

Concentra Biosciences, LLC and Tang Capital Partners, LP

4747 Executive Drive, Suite 210

San Diego, California 92121

In connection with your consideration of a possible negotiated business combination transaction between Theseus Pharmaceuticals, Inc. (the “Company”) and Concentra Biosciences, LLC (Concentra Biosciences, LLC and Tang Capital Parnters, LP and/or one or more of your affiliates, collectively referred to herein as “you”) (the “Possible Transaction”), you have requested information concerning the Company that is confidential and proprietary. As a condition to your being furnished such information, you agree to treat any information, in any form or medium, whether written or oral, relating to the Company or any of its subsidiaries, affiliates or divisions (whether prepared by the Company, its advisors or otherwise) that is furnished to you before, on or after the date of this letter agreement, by or on behalf of the Company (herein collectively referred to as the “Evaluation Material”) in accordance with the provisions of this letter agreement and to take or abstain from taking certain other actions herein set forth. The term “Evaluation Material” includes, without limitation, all notes, analyses, compilations, spread sheets, data, reports, studies, interpretations or other documents furnished to you or your Representatives (as defined below) or prepared by you or your Representatives to the extent such materials reflect or are based upon, in whole or in part, the Evaluation Material. The term “Evaluation Material” does not include information that (a) is or becomes available to you on a nonconfidential basis from a source other than the Company or its Representatives; provided that such source is not known by you to be bound by a confidentiality agreement with, or other contractual, legal or fiduciary obligation to, the Company that prohibits such disclosure, (b) is or becomes generally available to the public other than as a result of a disclosure by you or your Representatives in violation of this letter agreement, or (c) has been or is independently developed by you or your Representatives without the use of the Evaluation Material or in violation of the terms of this letter agreement. For purposes of this letter agreement, the term “Representatives” shall include (i) when used in relation to the Company, the Company’s subsidiaries and Affiliates (as such term is defined in Rule 12b-2 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”)) and its and their respective directors, officers, consultants, employees, attorneys, accountants, financial advisors and other professional representatives, and (ii) when used in relation to you, your subsidiaries and Affiliates and your and their respective directors, officers, employees, attorneys, accountants, financial advisors and other professional representatives. You hereby agree that the Evaluation Material will be kept confidential and used solely for the purpose of evaluating and negotiating the Possible Transaction; provided, however, that the Evaluation Material may be disclosed (i) to your Representatives who need to know such information for the sole purpose of evaluating and negotiating a Possible Transaction, (ii) pursuant to an External Demand in accordance with paragraph 4 of this letter agreement, and (iii) as the Company may otherwise consent in writing. All such Representatives shall (A) be informed by you of the confidential nature of the Evaluation Material, (B) agree to keep the Evaluation Material strictly confidential, and (C) be advised of the terms of this letter agreement and agree to be bound by the terms hereof to the same extent as if they were parties to this letter agreement. You agree to be responsible for any breaches of any of the provisions of this letter agreement by any of your Representatives (it being understood that such responsibility shall be in addition to and not by way of limitation of any right or remedy the Company may have against your Representatives with respect to such breach). It is understood and agreed that the Company may, in its sole discretion, from time to time determine that disclosure of certain Evaluation Material to certain of your Representatives may be inappropriate, in which event at the Company’s request, you shall refrain from disclosing such Evaluation Material to such Representatives.

You will not, and will direct your Representatives not to (and Transaction Information shall only be disclosed to your Representatives who need to know such information for the sole purpose of evaluating and negotiating a Possible Transaction), disclose to any person (including any governmental agency, authority or official or any third party) either the fact that discussions or negotiations are taking place (or have taken place) concerning the Possible Transaction or any of the terms, conditions or other facts with respect to the Possible Transaction, including the status thereof or that Evaluation Material has been made available to you (such information, “Transaction Information”); provided, however, that disclosure of Transaction Information pursuant to an External Demand shall be governed by paragaph 4 of this letter agreement; provided further, however, that, other than in the case of an External Demand, you and your Affiliates may disclose Transaction Information (a “Permitted Disclosure”) if but only if (i) such disclosure is required under applicable securities or antitrust laws or under applicable stock exchange rules and (ii) such disclosure requirement does not arise from a breach of this letter agreement. Without limiting the generality of the foregoing, you further agree that you will not, directly or indirectly, contact, share the Evaluation Material or Transaction Information with or enter into any agreement, arrangement or understanding, or any discussions which would reasonably be expected to lead to an agreement, arrangement or understanding, with any other person, including financing sources (other than your Representatives as permitted above) regarding a Possible Transaction involving the Company without the prior written consent of the Company and only upon such person executing a confidentiality agreement in favor of the Company with terms and conditions consistent with this letter agreement.

You hereby acknowledge that you and your Representatives are aware that the Evaluation Material and Transaction Information may contain material, non-public information about the Company and you hereby agree that you and your Representatives may not purchase or sell any securities of the Company on the basis of such information.

Notwithstanding anything to the contrary provided in this letter agreement in the event you or any of your Representatives receive a request or are required by deposition, interrogatory, request for documents, subpoena, civil investigative demand or similar process or pursuant to a formal request from a regulatory examiner (any such requested or required disclosure, an “External Demand”) to disclose all or any part of the Evaluation Material, you or your Representatives, as the case may be, agree to (a) promptly notify the Company in writing of the existence, terms and circumstances surrounding such External Demand, (b) consult with the Company on the advisability of taking legally available steps to resist or narrow such request or disclosure, and (c) assist the Company, at the Company’s expense, in seeking a protective order or other appropriate remedy to the extent available under the circumstances, in each case of (a) – (c), to the extent practicable and legally permitted. In the event that such protective order or other remedy is not obtained or that the Company waives compliance with the provisions hereof, (i) you or your Representatives, as the case may be, may disclose only that portion of the Evaluation Material or Transaction Information which you or your Representatives are advised by outside legal counsel is legally required to be disclosed and to only those persons to whom you or your Representatives are advised by outside legal counsel are legally required to receive such information, and you or your Representatives shall exercise reasonable best efforts to obtain assurance that confidential treatment will be accorded such Evaluation Material or Transaction Information, and (ii) you or your Representatives shall not be liable for such disclosure, unless such disclosure was caused by or resulted from a previous disclosure by you or your Representatives not permitted by this letter agreement.

Unless otherwise agreed to by the Company in writing, (a) all communications regarding the Possible Transaction, (b) requests for additional information, (c) requests for management meetings, and (d) discussions or questions regarding procedures, timing and terms of the Possible Transaction, should be submitted or directed exclusively to Leerink Partners LLC (the “Banker”). Contact information for the appropriate Banker representatives shall be provided by the Company.

You agree that, for a period of two (2) years from the date hereof, neither you nor any of your Affiliates who are provided with Evaluation Material or Transaction Information, or any of your Representatives acting on your behalf or at your direction, will, directly or indirectly, solicit for employment or employ or cause to leave the employ of the Company or any of its subsidiaries (a) any individual serving as an officer of the Company, or (b) any employee of the Company or any of its subsidiaries with whom you have had substantial contact, or who is specifically identified to you, during your investigation of the Company and its business, in each case without obtaining the prior written consent of the Company; provided that you may make general solicitations for employment not specifically directed at the Company or any of its subsidiaries or their respective employees and employ any person who responds to such solicitations.

(a)

From the date hereof until 5:00 p.m., Eastern time, on the date that is 45 days from the date hereof, except pursuant to the consummation of a Possible Transaction, neither you nor any of your Affiliates, shall, without the prior written consent of the Company, in any manner, directly or indirectly: (i) engage in any “solicitation” of “proxies” (as such terms are defined in Rule 14a 1 of Regulation 14A under the Securities Exchange Act of 1934, as amended, disregarding clause (iv) of Rule 14a 1(l)(2) and including any otherwise exempt solicitation pursuant to Rule 14a 2(b)) or consents to vote any voting securities of the Company or any of its Affiliates; (ii) form, join or in any way participate in a “group” (as such term is used in the rules of the United States Securities and Exchange Commission) (or discuss with any third party the potential formation of a group) with respect to any securities (including in derivative form) of the Company; (iii) make any public announcement or take any action which might force the Company to make a public announcement regarding any of the types of matters set forth in clause (i) of this Section; (iv) publicly request or propose that the Company or any of the Company’s Affiliates amend or waive, or consider the amendment or waiver of, any provision set forth in this Section; (v) publicly propose any merger, consolidation, business combination, tender or exchange offer, purchase of the Company’s assets or businesses, or similar transactions involving the Company; (vi) to the extent the Company provides you with material, non-public information about the Company, acquire beneficial ownership of any securities (including in derivative form) of the Company; or (vii) cause, assist, induce or encourage any other person or entity to take any action described in clauses (i) – (vi) above; provided, however, that the restrictions set forth in this Section shall terminate immediately upon the public announcement by the Company that it has, since the date of this letter agreement, entered into a definitive agreement with a third party for a transaction involving the acquisition (by way of merger, tender offer or otherwise) of more than 50% of the outstanding capital stock of the Company or 50% or more of the assets (on a consolidated basis) of the Company.

(b)

Notwithstanding anything in this letter agreement to the contrary, you and your Affiliates are permitted to make any disclosure or statement required under applicable laws, including required disclosures or statements on their Schedule 13D or amendments thereto.

(c)

Company acknowledges that you are in the investment business. Company acknowledges and understands that you may now or in the future evaluate, invest in or do business with competitors or potential competitors of the Company. Accordingly, provided that you do not violate any of the obligations under this letter agreement or applicable securities laws, nothing in this letter agreement will be construed as a representation or agreement that you will not continue to evaluate, invest in or do business with competitors or potential competitors of the Company.

You understand that none of the Company, the Banker, or their respective Representatives have made or make any representation or warranty, express or implied, as to the accuracy or completeness of the Evaluation Material. You agree that none of the Company, the Banker, or their respective Representatives shall have any liability to you or any of your Representatives resulting from the selection, use or content of the Evaluation Material by you or your Representatives.

Upon the Company’s (directly or through the Banker) demand, you shall either promptly (a) destroy the Evaluation Material and any copies thereof (including material that references Transaction Information), or (b) return to the Company all Evaluation Material and any copies thereof (including material that references Transaction Information), and, in either case, confirm in writing to the Company that all such material has been destroyed or returned, as applicable, in compliance with this letter agreement. It is understood that information in an intangible or electronic format containing Evaluation Material or Transaction Information cannot be removed, erased or otherwise deleted from archival systems (also known as “computer or system back-ups”) but that such information will continue to be protected under the confidentiality requirements and non-use limitations contained in this letter agreement and you and such Representatives shall continue to be bound by the obligations of confidentiality and non-use hereunder. Notwithstanding the foregoing, you and your Representatives may retain one copy of any work product prepared by you or them that contains Evaluation Material or Transaction Information to the extent necessary pursuant to applicable legal or regulatory requirements; provided that you and such Representatives shall continue to be bound by the obligations of confidentiality and non-use hereunder for such period of time as you and such Representatives retain such work product.

10.

You agree that, except to the extent expressly authorized by the Company’s Board of Directors (or any authorized committee thereof) in advance, neither you nor any of your Representatives acting on your behalf or at your direction will directly or indirectly have any formal or informal discussions or other communications, or directly or indirectly enter into any agreement, arrangement or understanding, whether formal or informal and whether or not binding, with any director, officer or other employee of the Company or any of its subsidiaries relating to (i) any retention, severance, equity or other compensation, incentives or benefits that may be or become payable to any directors, officers or employees of the Company or any of its subsidiaries in connection with a Possible Transaction or following the consummation thereof, or (ii) any directorship, employment, consulting arrangement or other similar association or involvement of any directors, officers or other employees of the Company or any of its subsidiaries with the Company or any Affiliate of the Company following the consummation of a Possible Transaction.

11.

To the extent that any Evaluation Material may include material subject to the attorney-client privilege, work product doctrine or any other applicable privilege concerning pending or threatened legal (including with respect to intellectual property matters) or regulatory proceedings or governmental investigations, the parties hereto understand and agree that they have a commonality of interest with respect to such matters and it is their desire, intention and mutual understanding that the disclosure of such material is not intended to, and will not, waive or diminish in any way the confidentiality of such material or its continued protection under the attorney-client privilege, work product doctrine or other applicable privilege and any such Evaluation Material will remain entitled to all protection under these privileges, this letter agreement and the joint defense doctrine. Nothing in this letter agreement obligates any party to reveal material subject to the attorney-client privilege, work product doctrine or any other applicable privilege, and in the event of an inadvertent disclosure of any materials which may have the effect of waiving any such privilege, you and your Representatives agree to destroy any such materials promptly upon the request of the Company or its Representatives.

12.

You represent and warrant that, as of the date hereof, you and your controlled Affiliates beneficially own less than 10% of the common stock of the Company, consistent with your Schedule 13D filed on November 24, 2023.

13.

You acknowledge and agree that money damages would not be a sufficient remedy for any breach (or threatened breach) of this letter agreement by you or your Representatives and that the Company shall be entitled to equitable relief, including injunction and specific performance, as a remedy for any such breach (or threatened breach), without proof of damages, and each party further agrees to waive, and shall cause its Representatives to waive any requirement for the securing or posting of any bond in connection with any such remedy. Such remedies shall not be the exclusive remedies for a breach of this letter agreement but will be in addition to all other remedies available at law or in equity.

14.

You agree that unless and until a definitive agreement between the Company and you with respect to the Possible Transaction has been executed and delivered, neither the Company nor you will be under any legal obligation of any kind whatsoever with respect to any transaction by virtue of this or any written or oral expression except, in the case of this letter agreement, for the matters specifically agreed to herein. In addition, you hereby waive, in advance, any claims (including, without limitation, breach of contract) in connection with any Possible Transaction other than claims under any definitive agreement relating to a Possible Transaction or under this letter agreement. For purposes of this letter agreement, the term “definitive agreement” does not include an executed letter of intent or any other preliminary written agreement, nor does it include any oral acceptance of an offer or bid by you. The agreement set forth in this paragraph may be modified or waived only by a separate writing by the Company and you expressly so modifying or waiving such agreement.

15.

You acknowledge that (a) the Company and the Banker shall be free to conduct the process for a transaction as they in their sole discretion shall determine (including, without limitation, negotiating with any prospective buyers and entering into a definitive agreement without prior notice to you or to any other person), and (b) any procedures relating to such transaction may be implemented or changed at any time without notice to you or any other person.

16.

No failure or delay by the Company or any of its Representatives in exercising any right, power or privilege under this letter agreement shall operate as a waiver thereof unless in writing and signed by an officer of the Company or other authorized person on its behalf. No modification or amendment of this letter agreement shall be effective unless in writing and signed by an officer of the Company, or other authorized person on its behalf, and you, or an authorized person on your behalf.

17.

The illegality, invalidity or unenforceability of any provision hereof under the laws of any jurisdiction shall not affect its legality, validity or enforceability under the laws of any other jurisdiction, nor the legality, validity or enforceability of any other provision.

18.

This letter agreement shall be governed by, and construed in accordance with, the laws of the State of Delaware. The parties hereby irrevocably and unconditionally consent to the exclusive jurisdiction of the Chancery Courts in the State of Delaware and the United States District Court for the District of the State of Delaware for any action, suit or proceeding arising out of or relating to this letter agreement and the Possible Transaction, and agree not to commence any action, suit or proceeding related thereto except in such courts.

19.

This letter agreement may be executed in two or more counterparts, each of which shall be deemed an original, but all of which shall constitute the same agreement. One or more counterparts of this letter agreement may be delivered by facsimile or pdf electronic transmission, with the intention that they shall have the same effect as an original counterpart hereof.

20.

This letter agreement shall terminate on the first anniversary of the date of this letter agreement (the “Termination Date”). The obligations of paragraph 6 shall survive the Termination Date and continue in accordance with the terms of that paragraph.

Very truly yours,

THESEUS PHARMACEUTICALS, INC.


By:	/s/ Brad Dahms
Name:	Brad Dahms
Title:	Chief Financial Officer



Confirmed and Agreed to:

Concentra Biosciences, LLC


By:	/s/ Michael Hearne
Name:	Michael Hearne
Title:	Chief Financial Officer

Date: 12/2/2023



Tang Capital Partners, LP


By:	/s/ Michael Hearne
Name:	Michael Hearne
Title:	Chief Financial Officer of Tang Capital Management, LLC, General Partner

Date: 12/2/2023

Exhibit (d)(4)

LIMITED GUARANTY

This Limited Guaranty, dated as of December 22, 2023 (as may be amended, restated, supplemented or otherwise modified, this “Limited Guaranty”), by Tang Capital Partners, LP (the “Guarantor”), is made in favor of Theseus Pharmaceuticals, Inc., a Delaware corporation (the “Company”) and the Representative to be party to the CVR Agreement (as defined below) (the “Representative”). Reference is hereby made to (i) that certain Agreement and Plan of Merger, dated as of the date hereof (the “Merger Agreement”), by and among Parent, Merger Sub and the Company, pursuant to which, among other things, Merger Sub will merge with and into the Company with the Company continuing as the surviving corporation in the merger as a wholly owned subsidiary of Parent, on the terms and subject to the conditions set forth in the Merger Agreement and (ii) that certain Contingent Value Rights Agreement (the “CVR Agreement”) to be entered into in accordance with the Merger Agreement by and among the Parent, Merger Sub, the Rights Agent (as defined in the CVR Agreement) and the Representative. As used in this Limited Guaranty, references to the “Guaranteed Party” shall mean (i) the Company with respect to the Guaranteed Purchase Price Obligation and the Guaranteed Damages Obligation and (ii) the Representative with respect to the Guaranteed CVR Obligation. Capitalized terms used herein but not otherwise defined herein have the meanings ascribed to them in the Merger Agreement or the CVR Agreement.

1. Limited Guaranty.

(a) As consideration for the Guaranteed Party entering into the Merger Agreement and the CVR Agreement, the Guarantor, intending to be legally bound, hereby absolutely, irrevocably and unconditionally guarantees to the Guaranteed Party, subject to the terms and conditions hereof:

(i) the obligation of Parent to fund all amounts payable by Parent pursuant to the terms of the Merger Agreement in connection with consummation of the transactions contemplated thereby (for the avoidance of doubt, such obligations shall include payment of Offer Price, the Merger Consideration, the Company Stock Option Cash Consideration and the Restricted Stock Unit Cash Consideration, without duplication), together with related fees and expenses (collectively, the “Guaranteed Purchase Price Obligation”), provided that the maximum amount of all Guaranteed Purchase Price Obligations shall not exceed $177,614,912 plus all such fees and expenses (the “Maximum Purchase Price Obligation”);

(ii) the payment obligations of the Parent to perform the covenants set forth in the CVR Agreement, including to pay the aggregate CVR Payment Amount (as defined in the CVR Agreement), together with any Enforcement Costs, in each case under and in accordance with the terms, conditions and limitations of the CVR Agreement, subject to, in the case of any such Enforcement Costs payable under the CVR Agreement, the Expense Cap (as defined in the CVR Agreement) (collectively, the “Guaranteed CVR Obligation”), provided that the maximum amount of the Guaranteed CVR Obligation shall not exceed the CVR Proceeds plus all such Enforcement Costs up to the Expense Cap (the “Maximum CVR Obligation” and, together with the Maximum Purchase Price Obligation, the “Maximum Guarantor Obligation”); and

(iii) the obligation of Parent or Merger Sub to pay monetary damages to the Guaranteed Party in connection with a Willful Breach by Parent or Merger Sub of the Merger Agreement pursuant to a final non-appealable judgment by a court of competent jurisdiction in accordance with Section 9.02 of the Merger Agreement, together with any Enforcement Costs (collectively, the “Guaranteed Damages Obligation” and, together with the Guaranteed Purchase Price Obligation and the Guaranteed CVR Obligation, the “Guaranteed Obligations”).

The Guaranteed Purchase Price Obligation shall be reduced on a dollar-for-dollar basis by the amount that such obligation is actually satisfied by Parent or Merger Sub, as applicable, and the Guaranteed CVR Payment Obligation and Guaranteed Damages Obligation shall be reduced on a dollar-for-dollar basis by the amount that any such obligation is actually satisfied by Parent or the Company.

Notwithstanding anything herein to the contrary (with the exception of Guaranteed Damages Obligations), the Guaranteed Party hereby agrees that (a) in no event will the Guarantor be required to pay to any Person or Persons more than the Maximum Guarantor Obligation, in respect of or in connection with this Limited Guaranty, the Merger Agreement, the CVR Agreement or any other document or instrument delivered in connection herewith or therewith, or the transactions contemplated hereby or thereby (or the termination or abandonment thereof) or otherwise, and (b) the Guarantor shall not have any obligation or liability to any Person or Persons (including, without limitation, to the Holders (as defined in the CVR Agreement), Affiliates and subsidiaries) relating to, arising out of or in connection with this Limited Guaranty, the Merger Agreement, the CVR Agreement or any other document or instrument delivered in connection herewith or therewith, or the transactions contemplated hereby or thereby (or the termination or abandonment thereof) or otherwise, other than as expressly set forth herein and solely to the extent hereof. Notwithstanding anything to the contrary contained in this Limited Guaranty, the Merger Agreement, the CVR Agreement or any other document or instrument delivered in connection herewith or therewith or otherwise, the Guaranteed Party hereby agrees that to the extent Parent, Merger Sub or the Company is relieved of all or any portion of its payment or performance obligations under the Merger Agreement or CVR Agreement, by satisfaction or waiver thereof or pursuant to any other agreement with the Guaranteed Party, the Guarantor shall be similarly relieved, to such extent, of their respective obligations under this Limited Guaranty.

2. Terms of Limited Guaranty.

(a) This Limited Guaranty is an unconditional and continuing guarantee of payment, not of collection, and a separate action or actions may be brought and prosecuted against the Guarantor to enforce this Limited Guaranty up to an amount equal to the Maximum Guarantor Obligation or any Guaranteed Damages Obligation. All payments to be made hereunder by the Guarantor shall be made in lawful money of the United States at the time of payment, and shall be made in immediately available funds.

(b) The liability of the Guarantor under this Limited Guaranty shall, to the fullest extent permitted under Applicable Law, be absolute, irrevocable and unconditional, irrespective of:

(i) the value, genuineness, validity, illegality or enforceability of the Merger Agreement or the CVR Agreement or any other agreement or instrument referred to herein or therein;

(ii) any release or discharge of any obligation of Parent, Merger Sub or the Company contained in the Merger Agreement or the CVR Agreement resulting from any change in the corporate existence, structure or ownership of Parent, Merger Sub or the Company, or any insolvency, bankruptcy, reorganization, liquidation or other similar proceeding affecting Parent, or any other Person now or hereafter interested in the transactions contemplated by the Merger Agreement or CVR Agreement, or any of their respective assets;

(iii) any amendment, modification or waiver of the Merger Agreement or CVR Agreement, or any change in the manner, place or terms of payment or performance of, any change or extension of the time of payment or performance of, or any renewal or alteration of any Guaranteed Obligation, any escrow arrangement or other security therefor, or any liability incurred directly or indirectly in respect thereof;

(iv) the existence of any claim, set-off or other right that the Guarantor may have at any time against Parent, Merger Sub, the Company or the Guaranteed Party, whether in connection with any Guaranteed Obligation or otherwise;

(v) the failure or delay of the Guaranteed Party to assert any claim or demand or enforce any right or remedy against Parent, Merger Sub, the Company or Guarantor or any other Person primarily or secondarily liable with respect to any Guaranteed Obligation (including in the event any Person becomes subject to a bankruptcy, reorganization, insolvency, liquidation or similar proceeding);

(vi) the adequacy of any other means the Guaranteed Party may have of obtaining payment of any of the Guaranteed Obligations; or

(vii) any other act or omission that may in any manner or to any extent vary the risk of the Guarantor or otherwise operate as a discharge of the Guarantor as a matter of law or equity (other than as a result of payment of the Guaranteed Obligations in accordance with their terms); other than in each case with respect to this Limited Guaranty, a breach by the Guaranteed Party of this Limited Guaranty, and, notwithstanding any other provision of this Limited Guaranty to the contrary, the Guarantor may assert, as a defense to, or release or discharge of, any payment or performance by the Guarantor under this Limited Guaranty, any claim, set-off, deduction, defense or release that Parent or Merger Sub could assert against the Guaranteed Party subject to the terms of the Merger Agreement and CVR Agreement that would relieve Parent, Merger Sub or the Company of its obligations under the Merger Agreement or CVR Agreement, as applicable.

(c) The Guarantor hereby waives any and all notice of the creation, renewal, extension or accrual of any of the Guaranteed Obligations and notice of or proof of reliance by the Guaranteed Party upon this Limited Guaranty or acceptance of this Limited Guaranty. Without expanding the obligations of the Guarantor hereunder, the Guaranteed Obligations, and any of them, shall conclusively be deemed to have been created, contracted or incurred in reliance upon this Limited Guaranty, and all dealings between Parent, Merger Sub, the Company and/or the Guarantor, on the one hand, and the Guaranteed Party, on the other, shall likewise be conclusively presumed to have been had or consummated in reliance upon this Limited Guaranty. When pursuing any of its rights and remedies hereunder against the Guarantor, the Guaranteed Party shall be under no obligation to pursue (or elect among) such rights and remedies they may have against Parent, Merger Sub, or the Company or any other Person for the Guaranteed Obligations or any right of offset with respect thereto, and any failure by the Guaranteed Party to pursue (or elect among) such other rights or remedies or to collect any payments from Parent, Merger Sub, or the Company or any such other Person or to realize upon or to exercise any such right of offset, and any release by the Guaranteed Party of Parent, Merger Sub, or the Company or any such other Person or any right of offset, shall not relieve the Guarantor of any liability hereunder, and shall not impair or affect the rights and remedies, whether express, implied or available as a matter of law, of the Guaranteed Party, subject to the provisions of Section 2(b).

(d) The Guarantor hereby irrevocably waive promptness, diligence, grace, acceptance hereof, presentment, demand, notice of non-performance, default, dishonor and protest and any other notice not provided for herein (except for notices to be provided to Parent and its counsel pursuant to the terms of the Merger Agreement or CVR Agreement, as applicable).

(e) The Guaranteed Party shall not be obligated to file any claim relating to any Guaranteed Obligation in the event that Parent, Merger Sub or the Company becomes subject to a bankruptcy, insolvency, reorganization or similar proceeding, and the failure of the Guaranteed Party to so file shall not affect the Guarantor’s obligation hereunder. In the event that any payment to the Guaranteed Party in respect of any Guaranteed Obligation is rescinded or must otherwise be returned to Parent, Merger Sub, the Company, the Guarantor or any other Person for any reason whatsoever, the Guarantor shall remain liable hereunder with respect to such Guaranteed Obligation as if such payment had not been made so long as this Limited Guaranty has not terminated in accordance with its terms.

3. Sole Remedy; No Recourse. Notwithstanding anything that may be expressed or implied in this Limited Guaranty or any document or instrument delivered in connection herewith, by its acceptance of the benefits of this Limited Guaranty, the Guaranteed Party further agrees that, except for (a) the Guaranteed Party’s rights against the Guarantor under this Limited Guaranty, (b) the Guaranteed Party’s remedies against Parent and Merger Sub and the Company and their assignees under the Merger Agreement and CVR Agreement and (c) remedies against the Guarantor under the Confidentiality Agreement (collectively, the “Permitted Claims”), neither the Guaranteed Party nor any other Person (including, without limitation, the Holders (as defined in the CVR Agreement), Affiliates and subsidiaries) has any right of recovery against, and no personal liability shall attach to, the Guarantor, any former, current or future, direct or indirect director, officer, employee, agent or Affiliate of the Guarantor, any former, current or future, direct or indirect holder of any equity interests or securities of the Guarantor (whether such holder is a limited or general partner, member, manager, stockholder or otherwise), any former, current or future assignee of the Guarantor, or any former, current or future director, officer, employee, agent, general or limited partner, manager, member, stockholder, Affiliate, controlling person, representative or assignee of any of the foregoing (each such Person, a “Related Person”), relating to, arising out of, or in connection with this Limited Guaranty, the Merger Agreement, the CVR Agreement or any documents related hereto or thereto (the “Related Documents”) or the transactions contemplated hereby or thereby, through Parent, Merger Sub, the Company or otherwise, whether by or through attempted piercing of the corporate, limited liability company or limited partnership veil, by or through a claim by or on behalf of Parent against the Guarantor or any Related Person. The Permitted Claims shall be the sole and exclusive remedies of (i) the Guaranteed Party and (ii) all of its respective Holders (as defined in the CVR Agreement), Affiliates and Subsidiaries against the Guarantor and its Related Persons in respect of any liabilities or obligations relating to, arising out of, or in connection with, this Limited Guaranty, the Merger Agreement, the CVR Agreement, the Related Documents or the transactions contemplated hereby or thereby, including by or through attempted piercing of the corporate veil or similar action, by the enforcement of any assessment or by any proceeding at law or equity by or on behalf of Parent, Merger Sub or the Company. The Guaranteed Party hereby covenants and agrees that the Guaranteed Party shall not institute and shall cause its controlled Affiliates and subsidiaries not to institute, any proceeding or bring any other claim arising under, or in connection with, this Limited Guaranty, the Merger Agreement, the CVR Agreement, the Related Documents or the transactions contemplated hereby or thereby (or the failure of such to be consummated), against the Guarantor or its Related Persons, except for the Permitted Claims by or on behalf of the Guaranteed Party and its respective controlled Affiliates and subsidiaries, and the Guaranteed Party waives any and all claims arising under, or in connection with, the Merger Agreement, this Limited Guaranty, the CVR Agreement, the Confidentiality Agreement, the Related Documents or, in each case, the transactions contemplated hereby or thereby against the Guarantor or its respective Related Persons and release such Persons from such claims, in each case, except for Permitted Claims. Nothing set forth in this Limited Guaranty shall affect or be construed to affect any liability of Parent, Merger Sub or the Company to the Guaranteed Party or shall confer or give or shall be construed to confer or give to any Person (including any Person acting in a representative capacity or any equity holder of the Guaranteed Party) other than the Guaranteed Party any rights or remedies against any Person, including the Guarantor, except as expressly set forth herein.

4. Subrogation. The Guarantor will not exercise against Parent, Merger Sub or the Company any rights of subrogation or contribution, whether arising by contract or operation of law (including, without limitation, any such right arising under bankruptcy or insolvency laws) or otherwise, by reason of any payment by it pursuant to the provisions of Section 1 hereof unless and until the Guaranteed Obligations have been paid in full.

5. Termination. This Limited Guaranty shall automatically and immediately terminate (and the Guarantor shall have no further obligations hereunder) (A) with respect to the Guaranteed Purchase Price Obligation, upon the earliest to occur of (i) the Merger Closing Date (and payment in full of all amounts required to be paid under Section 3.09(a) of the Merger Agreement), (ii) the payment in full of the Guaranteed Purchase Price Obligation and (iii) the valid termination of the Merger Agreement in accordance with its terms; provided, however, that, for the avoidance of doubt, any purported termination of the Merger Agreement that is not a valid termination shall not give rise to a termination of this Limited Guaranty pursuant to this Section 5, (B) with respect to the Guaranteed CVR Obligation, upon the earliest to occur of (i) the payment in full of the Guaranteed CVR Obligation and (ii) the valid termination of the CVR Agreement in accordance with its terms, and (C) with respect to the Guaranteed Damages Obligation, upon termination of the Merger Agreement in accordance with its terms (other than a termination if and to the extent that no later than the 90th day immediately following such termination, the Company shall have commenced a Proceeding against Parent or Merger Sub in a court of competent jurisdiction seeking monetary damages for a Willful Breach of the Merger Agreement by Parent or Merger Sub arising prior to termination thereof, in which case this Limited Guaranty, and the obligations and liability of the Guarantor hereunder, in respect of the Guaranteed Damages Obligation shall terminate no later than the earlier of the final adjudication of such claim after which no further appeal may be taken or the written agreement of the parties in settlement of such claim and terminating such Proceeding). In the event that prior to the Merger Closing Date the Guaranteed Party expressly asserts, on behalf of any of its controlled Affiliates or subsidiaries, in any litigation or other legal proceeding relating to this Limited Guaranty (i) that the provisions hereof (including, without limitation, Section 1 hereof limiting the Guarantor’s aggregate liability to the Maximum Guarantor Obligation (with the exception of Guaranteed Damages Obligations) or Section 3 hereof relating to the sole and exclusive remedies of the Guaranteed Party and the Holders (as defined in the CVR Agreement), Affiliates and subsidiaries against the Guarantor or its Related Persons) are illegal, invalid or unenforceable, in whole or in part, or (ii) any theory of liability against the Guarantor or its Related Persons other than any Permitted Claim, then (x) the obligations of the Guarantor under this Limited Guaranty shall terminate ab initio and be null and void, (y) if the Guarantor has previously made any payments under this Limited Guaranty, the Guarantor shall be entitled to recover such payments from the Guaranteed Party and (z) neither the Guarantor nor its Related Persons shall have any liability to the Guaranteed Party or any of their respective Holders, Affiliates or subsidiaries with respect to this Limited Guaranty.

6. Entire Agreement. This Limited Guaranty, the Merger Agreement, the CVR Agreement, the Confidentiality Agreement and the Related Documents constitute the entire agreement with respect to the subject matter hereof, and supersede all other prior agreements and understandings, both written and oral, among Parent, Merger Sub, the Company and/or the Guarantor or any of their respective Affiliates, on the one hand, and the Guaranteed Party or any of its Affiliates, on the other hand, and this Limited Guaranty is not intended to and shall not confer upon any Person (including, without limitation, the Holders (as defined in the CVR Agreement), Affiliates and subsidiaries) other than the parties hereto and any Related Person any rights or remedies. Except as expressly provided in this Limited Guaranty, no representation or warranty has been made or relied upon by any of the parties to this Limited Guaranty with respect to this Limited Guaranty.

7. Acknowledgement. The Guarantor hereby acknowledges and agrees that the Guarantor will not willfully and intentionally circumvent the payment mechanics under the CVR Agreement by taking dividends, distributions or payments from the Company using proceeds that should otherwise inure to the benefit of the Holders (as defined in the CVR Agreement). For the avoidance of doubt, until termination of the Guaranteed CVR Obligation, and subject to Section 8, the Guaranteed Party shall be entitled to enforce the Guarantor’s obligation under this Section 7.

8. Third-Party Beneficiaries. The Guarantor and the Guaranteed Party hereby agree that the covenants and agreements set forth herein solely with respect of the Guaranteed CVR Agreement Obligations, are intended to be for the benefit of all Holders (as defined in the CVR Agreement) and shall be enforceable by the Representative. The Representative, solely at the direction of and with the prior written consent of the Acting Holders (as defined in the CVR Agreement), will have the right, on behalf of all Holders, by virtue of or under any provision of this Limited Guaranty relating to the Guaranteed CVR Obligations, to institute any action or proceeding at law or in equity or in bankruptcy or otherwise upon or under or with respect to the Guaranteed CVR Obligations set forth in this Limited Guaranty, and no other Person or Persons will be entitled to exercise such rights. For avoidance of doubt and notwithstanding anything to the contrary herein, the Representative shall not commence any action under this Limited Guaranty on behalf of or to enforce the rights of the Holders except at the direction of and with the prior written consent of the Acting Holders.

9. Amendments and Waivers. Any provision of this Limited Guaranty may be amended or waived only in a writing signed by the Guarantor and the Guaranteed Party.

10. Notices. Any notice, request, or demand desired or required to be given hereunder will be in writing and will be given by personal delivery, email delivery, or overnight courier service, in each case addressed as respectively set forth below or to such other address as any party hereto will have previously designated by such a notice. The effective date of any notice, request, or demand will be the date of personal delivery, the date on which email is sent (provided that the sender of such email does not receive a written notification of delivery failure) or one day after it is delivered to a reputable overnight courier service, as the case may be, in each case properly addressed as provided in this Limited Guaranty and with all charges prepaid.

Notices to the Guarantor, Parent or Merger Sub:

Concentra Biosciences, LLC

4747 Executive Dr. Suite 210
San Diego, CA 92121
Attention: Kevin Tang
Email: ktang@concentrabiosciences.com

with a copy to (which shall not constitute notice):

Gibson, Dunn & Crutcher LLP
One Embarcadero Center, Suite 2600
San Francisco, CA 94111-3715
Attention: Ryan A. Murr
Email: rmurr@gibsondunn.com

Notices to the Guaranteed Party:

Theseus Pharmaceuticals, Inc.
314 Main Street, Suite 04-200
Cambridge, MA 02142

Attention: Brad Dahms
Email: bdahms@theseusrx.com

with a copy (which shall not constitute notice) to:

Goodwin Procter LLP
100 Northern Avenue
Boston, MA 02210

Attention: Blake Liggio
Email: bliggio@goodwinlaw.com

11. Governing Law. The provisions of Sections 10.06 (Governing Law), 10.08(b) (Jurisdiction) and 10.09 (Waiver of Jury Trial) of the Merger Agreement are hereby incorporated herein by reference, mutatis mutandis.

12. Representations and Warranties. The Guarantor hereby represents and warrants to the Guaranteed Party that (a) it has all limited partnership, corporate or other organizational power and authority to execute, deliver and perform this Limited Guaranty; (b) the execution, delivery and performance of this Limited Guaranty by it has been duly and validly authorized and approved by all necessary limited partnership, corporate or other organizational action by it; (c) this Limited Guaranty has been duly and validly executed and delivered by it and constitutes a valid and legally binding obligation of it, enforceable against it in accordance with the terms of this Limited Guaranty; (d) the Maximum Guarantor Obligation is less than the maximum amount that it is permitted to invest in any one portfolio investment pursuant to the terms of its constituent documents or otherwise; (e) it has, and will have at all times prior to the termination of this Limited Guaranty, uncalled capital commitments or otherwise has and will have at all times prior to the termination of this Limited Guaranty, available funds in excess of the sum of the Guaranteed Obligations (not to exceed the Maximum Guarantor Obligation) plus the aggregate amount of all other commitments and obligations it currently has outstanding; and (f) all consents, approvals, authorizations, permits of, filings with and notifications to, any Governmental Entity necessary for the due execution, delivery and performance of this Limited Guaranty by it have been obtained or made and all conditions thereof have been duly complied with, and no other action by, and no notice to or filing with, any Governmental Entity or regulatory body is required in connection with the execution, delivery or performance of this Limited Guaranty.

13. No Assignment. Neither this Limited Guaranty nor any of the rights, interests or obligations hereunder shall be assignable without the prior written consent of the Guaranteed Party (in the case of an assignment by the Guarantor) or the Guarantor (in the case of an assignment by any of the Guaranteed Party).

14. Severability. If any term or other provision of this Limited Guaranty is determined by a court of competent jurisdiction to be invalid, illegal or incapable of being enforced by any rule or law, or public policy, all other conditions and provisions of this Limited Guaranty shall nevertheless remain in full force and effect. Upon such determination that any term or other provision is invalid, illegal or incapable of being enforced, the parties hereto shall negotiate in good faith to modify this Limited Guaranty so as to effect the original intent of the parties hereto as closely as possible in an acceptable manner to the end that the transactions contemplated hereunder are fulfilled to the extent possible.

15. Headings. The headings contained in this Limited Guaranty are for reference purposes only and shall not affect in any way the meaning or interpretation of this Limited Guaranty.

[Remainder of page intentionally left blank]

IN WITNESS WHEREOF, the undersigned have caused this Limited Guaranty to be executed and delivered as of the date first written above.

Concentra Biosciences, LLC, as Parent

By:	/s/ Kevin Tang
Name:	Kevin Tang
Title:	Chief Executive Officer

Concentra Merger Sub II, Inc., as Merger Sub

By:	/s/ Kevin Tang
Name:	Kevin Tang
Title:	Chief Executive Officer

Tang Capital Partners, LP, as Guarantor

By:	/s/ Kevin Tang
Name:	Kevin Tang
Title:	President of Tang Capital Management, LLC, General Partner

[Signature Page to Limited Guaranty]

IN WITNESS WHEREOF, the undersigned have caused this Limited Guaranty to be executed and delivered as of the date first written above.

Theseus Pharmaceuticals, Inc., as Guaranteed Party

By:	/s/ Brad Dahms
Name:	Brad Dahms
Title:	Chief Financial Officer

[Signature Page to Limited Guaranty]

Exhibit 107

Calculation of Filing Fee Tables

SC TO-T

(Form Type)

Theseus Pharmaceuticals, Inc.

(Name of Subject Company – Issuer)

Concentra Merger Sub II, Inc.

(Names of Filing Persons — Offeror)

Concentra Biosciences, LLC

(Names of Filing Persons — Parent of Offeror)

Table 1: Transaction Valuation

	Transaction Valuation*	Fee Rate	Amount of Filing Fee**
Fees to Be Paid	$178,150,196.28	0.00014760	$26,294.97
Fees Previously Paid	$0.00		$0.00
Total Transaction Valuation	$178,150,196.28
Total Fees Due for Filing			$26,294.97
Total Fees Previously Paid			$0.00
Total Fee Offsets			$0.00
Net Fee Due			$26,294.97

The transaction valuation is estimated for purposes of calculating the amount of the filing fee only. The transaction valuation was estimated by multiplying (i) 44,649,172 issued and outstanding shares of common stock of Theseus Pharmaceuticals, Inc. (“Theseus”) to be acquired by Concentra Merger Sub II, Inc., par value $0.0001 per share (the “Shares”), which is based on information provided by Theseus as of January 8, 2024; and (ii) $3.99, the average of the high and low sales prices per Share on January 3, 2024, as reported by the Nasdaq Stock Market LLC (which, for the purposes of calculating the filing fee only, shall be deemed to be the Reference Price).

The amount of the filing fee was calculated in accordance with Rule 0-11 of the Securities Exchange Act of 1934, as amended, and Fee Rate Advisory #1 for fiscal year 2024 beginning on October 1, 2023, issued on August 25, 2023, by multiplying the transaction valuation by 0.00014760.

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