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): November 30, 2020

SUTRO BIOPHARMA, INC.

(Exact name of registrant as specified in its charter)

(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 5.02.  Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory

Arrangements of Certain Officers.

(d)

On November 30, 2020, the board of directors (the “Board”) of Sutro Biopharma, Inc. (the “Company”) appointed Jon Marc Wigginton, M.D., as a Class I director and member of the Science and Technology Committee, effective immediately.

In connection with his election as a non-employee director of the Board, Dr. Wigginton will receive a pro rata portion of the $40,000 annual retainer for service as a director for the remaining portion of the year, and a pro rata portion of the $5,000 annual retainer for service as a member of the Science and Technology Committee for the remaining portion of the year, each in accordance with the Company’s existing compensation policy for non-employee directors. In addition, the Board granted to Dr. Wigginton, effective November 30, 2020, a stock option to purchase 24,000 shares of common stock at an exercise price equal to the closing sale price of the common stock on November 30, 2020, as reported by the Nasdaq Global Market, which will vest monthly over three years, subject to Dr. Wigginton’s continued service to the Company.

The Company has entered into its standard form of indemnification agreement with Dr. Wigginton. The form of the indemnification agreement was previously filed by the Company as Exhibit 10.1 to the Company’s Registration Statement on Form S-1 filed with the Securities and Exchange Commission on September 17, 2018 and incorporated by reference herein.

There are no arrangements or understandings between Dr. Wigginton and any other persons pursuant to which Dr. Wigginton was selected as a member of the Board. There are also no family relationships between Dr. Wigginton and any director or executive officer of the Company, nor does Dr. Wigginton have a direct or indirect material interest in any transaction required to be disclosed pursuant to Item 404(a) of Regulation S-K.

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.