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): ~~August~~September 729, 2025

SUTRO BIOPHARMA, INC.

(Exact name of registrant as specified in its charter)

     Delaware

     001-38662

     47-0926186

     (State or other jurisdiction
of Incorporation)

     (Commission 
File Number)

     (IRS Employer
Identification No.)

    

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:


Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, $0.001 par value	STRO	The Nasdaq Global Market

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 2.~~02. Results~~05 ofCosts ~~Operations~~Associated ~~and~~with ~~Financial~~Exit ~~Condition.~~or Disposal Activities

On ~~August~~September 729, 2025, Sutro Biopharma, Inc. (the “Company”) ~~issued~~announced afurther ~~press~~organizational ~~release~~restructuring ~~announcing~~to prioritize the advancement of its ~~financial~~three ~~results~~preclinical ~~for~~ADC programs and its research and development collaborations. The restructuring is expected to extend the ~~quarter~~Company’s ~~ended~~runway ~~June~~into ~~30,~~at ~~2025~~least mid-2027 resulting from cost savings associated with the restructuring and certain expected near-term milestone payments. AFollowing ~~copy~~further prioritization of the ~~press~~ADC ~~release~~programs, isthe ~~attached~~Company asexpects ~~Exhibit~~initial 99clinical data to be available from STRO-004, its next-generation Tissue Factor-targeting exatecan ADC, in 2026.1 As part of the corporate restructuring, the Company plans to ~~this~~reduce ~~report~~its workforce by approximately one-third.

The ~~information~~total ~~furnished~~cash ~~with~~payments ~~Item~~and ~~2.02~~costs ofrelated ~~this~~to ~~report,~~the ~~including~~further ~~Exhibit~~prioritization ~~99.1,~~of isthe ~~being~~ADC ~~furnished~~programs and ~~shall~~reducing ~~not~~the beworkforce ~~deemed~~are ~~“filed”~~estimated ~~for~~to ~~purposes~~be ofapproximately ~~Section~~$4.1million 18to of$4.3 ~~the~~million, ~~Securities~~with ~~Exchange~~a ~~Act~~significant majority of ~~1934,~~these asamounts ~~amended~~expected ~~(the~~to ~~“Exchange~~be ~~Act”),~~paid orin ~~otherwise subject to~~ the ~~liabilities~~fourth quarter of ~~that~~2025. ~~section,~~These ~~nor~~estimates ~~shall~~are itsubject beto ~~deemed~~a ~~incorporated~~number byof ~~reference~~assumptions ~~into~~and ~~any~~actual ~~other~~results ~~filing~~may ~~under~~differ. ~~the~~The ~~Exchange~~Company ~~Act~~may oralso ~~under~~incur ~~the~~additional ~~Securities~~costs ~~Act~~not ofcurrently ~~1933,~~contemplated asdue ~~amended~~to ~~(the~~events ~~“Securities~~that ~~Act”),~~may ~~except~~occur as ~~expressly~~a ~~set~~result ~~forth~~of, byor ~~specific~~that ~~reference~~are inassociated ~~such~~with, athe ~~filing~~corporate restructuring.

A copy of the press release announcing the corporate restructuring is attached as Exhibit 99.1 to this Current Report on Form 8-K.

Item 9.01. Financial Statements and Exhibits

(d) Exhibits.

ExhibitNo.		Description
Exhibit Number		Description
99.1		Press ~~release~~Release issued by Sutro Biopharma, Inc. ~~regarding~~announcing ~~its~~operational ~~financial~~restructuring ~~results~~intended ~~for~~to ~~the~~extend ~~period~~cash ~~ended~~runway ~~June~~through ~~30,~~key ~~2025, dated August 7, 2025~~milestones.
104		Cover Page Interactive Data File (embedded within the Inline XBRL document).

Forward-Looking Statements

This Current Report on Form 8-K contains forward-looking statements within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995, and other federal securities laws. Any statements contained herein that do not describe historical facts, including, but not limited to, statements regarding anticipated preclinical and clinical development activities; timing of announcements of IND submissions, clinical results, trial initiation, and other regulatory filings; outcome of discussions with regulatory authorities; potential benefits of the Company’s product candidates and platform; potential business development and partnering transactions; potential market opportunities for the Company’s product candidates; the timing and receipt of anticipated future milestone payments; the Company’s expected cash runway; and the expected costs and cost reductions associated with the restructuring, are forward-looking statements that involve risks and uncertainties that could cause actual results to differ materially from those discussed in such forward-looking statements. Such risks and uncertainties include, among others, the risks identified in the Company’s filings with the SEC, including its Annual Report on Form 10-K for the fiscal year ended December 31, 2024, filed with the SEC on March 13, 2025. Any of these risks and uncertainties could materially and adversely affect the Company’s results of operations, which would, in turn, have a significant and adverse impact on the Company’s stock price. The Company cautions you not to place undue reliance on any forward-looking statements, which speak only as of the date they are made. The Company undertakes no obligation to update publicly any forward-looking statements to reflect new information, events or circumstances after the date they were made or to reflect the occurrence of unanticipated events.

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.

	Sutro Biopharma, Inc.
Date: August 7, 2025	By:	/s/ Gregory Chow
Date: September 29, 2025	By:	/s/ David Pauling
		Gregory Chow
		David Pauling
		Chief Financial Officer
		General Counsel and Chief Administrative Officer

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