CALA

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 OR 15(d)

of The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): June 14, 2022

Calithera Biosciences, Inc.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (650) 870-1000

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company   ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.   ☐

On June 14, 2022, Calithera Biosciences, Inc. filed a Certificate of Amendment to the Amended and Restated Certificate of Incorporation of Calithera Biosciences, Inc., or the Amendment, to effect a one-for-twenty (1:20) reverse stock split of our outstanding common stock, effective as of June 14, 2022, or the Reverse Stock Split. A series of alternate amendments to effect the Reverse Stock Split was approved by our stockholders at our Annual Meeting of Stockholders held on June 1, 2022, and the specific one-for-twenty (1:20) ratio was subsequently approved by our Board of Directors on June 8, 2022.

The Amendment provides that at the effective time of the Reverse Stock Split, every twenty shares of our issued and outstanding common stock will be automatically converted into one issued and outstanding share of common stock, without any change in par value per share. The Reverse Stock Split will affect all shares of our common stock outstanding immediately prior to the effective time of the Reverse Stock Split, as well as the number of shares of common stock available for issuance under our equity incentive plans and employee stock purchase plan. In addition, the Reverse Stock Split will effect a reduction in the number of shares of common stock issuable upon the conversion of shares of our Series A convertible preferred stock and upon the exercise of stock options or warrants outstanding immediately prior to the effectiveness of the Reverse Stock Split. No fractional shares will be issued because of the Reverse Stock Split. Stockholders who would otherwise be entitled to receive a fractional share will receive a cash payment in lieu thereof.

Our common stock is scheduled to begin trading on the Nasdaq Global Select Market on a split-adjusted basis when the market opens on June 15, 2022. The new CUSIP number for our common stock following the Reverse Stock Split is 13089P 507.

The foregoing description is qualified in its entirety by the Amendment, which is attached as Exhibit 3.1 to this Current Report on Form 8-K and is incorporated herein by reference.

(d) Exhibits.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

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