Initial Statement of Beneficial Ownership (3)

FORM 3	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0104 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person ^*

Anderson Kirstin

2. Date of Event Requiring Statement (MM/DD/YYYY) 8/26/2019

3. Issuer Name and Ticker or Trading Symbol

Sesen Bio, Inc. [SESN]

(Last) (First) (Middle)

C/O SESEN BIO INC, 245 FIRST STREET - SUITE 1800

4. Relationship of Reporting Person(s) to Issuer (Check all applicable)

_____ Director _____ 10% Owner
___X___ Officer (give title below) _____ Other (specify below)
Principal Accounting Officer /

(Street)

CAMBRIDGE, MA 02142

(City) (State) (Zip)

5. If Amendment, Date Original Filed(MM/DD/YYYY)

6. Individual or Joint/Group Filing(Check Applicable Line)

_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	32228 ⁽¹⁾	D

*Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)*
1. Title of Derivate Security (Instr. 4)	2. Date Exercisable and Expiration Date (MM/DD/YYYY)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
1. Title of Derivate Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	4. Conversion or Exercise Price of Derivative Security		6. Nature of Indirect Beneficial Ownership (Instr. 5)
Employee Stock Option (Right to Buy)	⁽²⁾	9/2/2024	Common Stock	2400.0	$11.95	D
Employee Stock Option (Right to Buy)	⁽³⁾	5/20/2025	Common Stock	2200.0	$3.1	D
Employee Stock Option (Right to Buy)	⁽⁴⁾	1/28/2026	Common Stock	2500.0 ⁽⁵⁾	$0.32	D
Employee Stock Option (Right to Buy)	⁽⁶⁾	10/3/2027	Common Stock	15000.0	$1.59	D
Employee Stock Option (Right to Buy)	⁽⁷⁾	4/9/2028	Common Stock	8000.0	$1.5	D
Employee Stock Option (Right to Buy)	⁽⁸⁾	2/21/2029	Common Stock	37000.0	$0.8285	D

Explanation of Responses:
(1)	Represents shares purchased at various dates through 09/14/2017 through the exercise of vested stock options and participation in the Company's 2014 Employee Stock Purchase Plan.
(2)	This option was granted on 09/03/2014. 25% of the shares subject to such option shall vest on the first anniversary of the date of grant of the option and an additional 6.25% of the shares underlying the option shall vest at the end of each successive three-month period thereafter until the fourth anniversary of the date of grant of the option.
(3)	This option was granted on 05/21/2015. 1/24th of the shares subject to such option shall vest on the 21st day of each successive month until the second anniversary of the date of grant of the option.
(4)	This option was granted on 01/29/2016. 6.25% of the shares subject to such option shall vest at the end of each successive three-month period until the fourth anniversary of the date of grant of the option.
(5)	469 vested options were exercised 12/06/2016 and are included above in common stock holdings.
(6)	This option was granted on 10/04/2017. 25% of the shares subject to such option were immediately vested and an additional 25% of the shares underlying the option shall vest at the end of each successive six-month period until 18 months after the date of grant of the option.
(7)	This option was granted on 04/09/2018. 6.25% of the shares subject to such option shall vest at the end of each successive three-month period until the fourth anniversary of the date of grant of the option.
(8)	This option was granted on 02/21/2019. 6.25% of the shares subject to such option shall vest at the end of each successive three-month period until the fourth anniversary of the date of grant of the option.

Remarks:
Form 3 filed as a result of designation as Principal Accounting Officer by the Board of Directors on 08/26/2019.
Exhibit List: Exhibit 24: Power of Attorney

Reporting Owners
Reporting Owner Name / Address	Relationships
Reporting Owner Name / Address	Director	10% Owner	Officer	Other
Anderson Kirstin C/O SESEN BIO INC 245 FIRST STREET - SUITE 1800 CAMBRIDGE, MA 02142			Principal Accounting Officer