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 8, 2023

SUTRO BIOPHARMA, INC.

(Exact name of registrant as specified in its charter)

111 Oyster Point Blvd,

South San Francisco, California, 94080

(Address of principal executive offices) (Zip Code)

(650) 881-6500

(Registrant’s telephone number, including area code)

Not Applicable

(Former name or former address, if changed since last report)

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:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

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. ☐

Item 1.02 Termination of a Material Definitive Agreement.

On June 9, 2023, Sutro Biopharma, Inc. (the “Company”) received a notice of termination (the "Notice") from Celgene Corporation, a Bristol Myers Squibb company (“BMS”), of the Amended and Restated Collaboration and License Agreement, dated as of August 2, 2017, by and among the Company, Celgene Corporation and Celgene Alpine Investment Company II, LLC, as amended (the “Agreement”). The Company and Celgene Corporation originally entered into the collaboration governed by the Agreement in 2014, prior to BMS’s acquisition of Celgene Corporation.

Under the Agreement, the Company and BMS had been collaborating on an antibody-drug conjugate program targeting B cell maturation antigen, CC-99712. The Company has been informed by BMS that the decision to terminate the Agreement and stop development of CC-99712 was the result of a portfolio prioritization decision.

The termination of the Agreement is effective as of October 7, 2023 (the "Termination Date"). From and after the Termination Date, the Company will have sole worldwide rights to CC-99712.

Item 5.07. Submission of Matters to a Vote of Security Holders.

On June 8, 2023, the Company held its 2023 Annual Meeting of Stockholders, and the following proposals were adopted:

SIGNATURE

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