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 16, 2021

SUTRO BIOPHARMA, INC.

(Exact name of registrant as specified in its charter)

310 Utah Avenue, Suite 150,

South San Francisco, California, 94080

(Address of principal executive offices) (Zip Code)

(650) 392-8412

(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:

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 1.01. Entry into a Material Definitive Agreement.

On June 16, 2021, Sutro Biopharma, Inc. (the “Company”) entered into a third amendment (the “Third Amendment”) to its manufacturing facility lease, dated May 18, 2011 as amended, by and between the Company and Alemany Plaza LLC, located at 894 Industrial Road, San Carlos, California (the “San Carlos Lease”), in order to extend the term of the San Carlos Lease for a period of five years (the “Lease Extension Period”).  Pursuant to the Third Amendment, the San Carlos Lease will expire on July 31, 2026, and it includes an option to renew the San Carlos Lease for an additional five years.  The aggregate estimated base rent payments due over the Lease Extension Period is approximately $4.2 million, subject to certain terms contained in the San Carlos Lease.

The foregoing description of the Third Amendment to the San Carlos Lease is qualified in its entirety by reference to the Third Amendment to the San Carlos Lease, a copy of which will be filed as an exhibit to the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2021.

Item 2.03 Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of Registrant.

The information set forth above in Item 1.01 of this Current Report on Form 8-K regarding the Third Amendment to the San Carlos Lease is incorporated into this Item 2.03 by reference.

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.