Welcome to our dedicated page for Sutro Biopharma SEC filings (Ticker: STRO), a comprehensive resource for investors and traders seeking official regulatory documents including 10-K annual reports, 10-Q quarterly earnings, 8-K material events, and insider trading forms.
Sutro Biopharma filings document the regulatory record of a clinical-stage oncology biotechnology company developing site-specific antibody-drug conjugates. Its SEC disclosures cover operating and financial results, research and development priorities, clinical and regulatory updates for ADC programs, collaboration-related matters, risk factors, and capital-structure activity involving its common stock.
The company’s filings also include definitive proxy materials on shareholder voting, board matters, executive compensation and equity awards. Form 8-K reports document material events such as agreement terminations, restructuring costs, Nasdaq listing-rule notices and compliance updates, and other corporate actions affecting governance, reporting status and financing flexibility.
Sutro Biopharma, Inc. reported the results of its 2026 Annual Meeting of Stockholders held on June 5, 2026. Stockholders elected directors Jane Chung, Connie Matsui, and James Panek, each receiving more votes “for” than “withheld,” with broker non-votes also recorded.
Stockholders also approved two additional proposals, with one receiving 13,893,289 shares voted for, 501 against, and 5,883 abstaining, and another receiving 11,329,946 shares for, 22,412 against, 6,452 abstentions, and 2,540,863 broker non-votes.
Sutro Biopharma CFO Gregory K. Chow exercised equity awards and increased his direct stake in the company. On June 2, 2026, he exercised Restricted Stock Units (RSUs) covering 2,500 shares of Common Stock, with no shares sold in this filing. Following the transaction, he directly holds 4,725 shares of Common Stock and 7,500 RSUs, each representing the right to receive one share upon settlement. Footnotes state that tax withholding obligations were satisfied in cash rather than by withholding shares, and that his total Common Stock holdings include 250 shares acquired under the company’s employee stock purchase plan.
Sutro Biopharma Schedule 13G discloses that affiliated investment entities and Srinivas Akkaraju together beneficially own disclosed stakes in the company's common stock. The filing lists 419,095 shares held by Samsara BioCapital, 643,777 shares held by Samsara Opportunity Fund, and 1,062,872 shares beneficially owned by the Reporting Persons in aggregate. The filing uses 16,567,238 shares outstanding as of March 16, 2026 as the basis for percentage calculations and reports percentages of 2.5%, 3.9%, and 6.4% for the listed holders. The report is signed by Srinivas Akkaraju on behalf of the Samsara entities.
Sutro Biopharma, Inc. Schedule 13G/A shows 872,558 shares of Common Stock were reported beneficially owned, representing 5.27% of the class as disclosed with a 03/31/2026 reference. The ownership is reported by Kynam Capital Management entities and Yue Tang, each with shared voting and dispositive power over the same 872,558 shares.
Sutro Biopharma reported first-quarter 2026 results showing a smaller loss and a strengthened balance sheet as it refocuses on its ADC pipeline. Revenue was $14.5M, down from $17.4M a year earlier, mainly from its collaboration with Astellas. Operating expenses fell sharply to $44.2M from $85.9M, reflecting completion of major restructuring and lower R&D and G&A costs.
Net loss improved to $38.5M (net loss per share $2.94) from $76.0M (net loss per share $9.08). Cash, cash equivalents and marketable securities totaled $202.6M as of March 31, 2026, boosted by a February underwritten offering of 7.87M shares that generated about $110M in gross proceeds. Management believes this cash position can fund operations for at least 12 months.
The company continues to carry a significant $229.1M deferred royalty obligation tied to the sale of future Vaxcyte royalties, which generated $9.5M in non-cash interest expense this quarter. Sutro is prioritizing its TF-targeting ADC STRO-004, now in a Phase 1 trial, and advancing preclinical candidates STRO-006 and dual-payload STRO-227 while maintaining key collaborations with Astellas and Vaxcyte.
Sutro Biopharma reported first quarter 2026 results showing lower revenue but a much smaller loss as it refocuses its pipeline. Revenue was $14.5 million for the quarter ended March 31, 2026, compared with $17.4 million a year earlier, mainly from its Astellas collaboration.
Net loss narrowed to $38.5 million from $76.0 million as total research, development and general and administrative expenses fell to $44.1 million from $64.9 million, reflecting prior restructuring. Cash, cash equivalents and marketable securities were $202.6 million as of March 31, 2026, up from $141.4 million at year-end 2025, and were further strengthened by a $110.0 million underwritten equity offering, extending cash runway into at least the second quarter of 2028.
Clinically, Sutro advanced its wholly owned ADC programs, including Phase 1 dose escalation of Tissue Factor–targeting STRO-004 with initial safety, pharmacokinetic and early activity data expected in mid-2026, and IND submissions planned in 2026 for ITGB6-targeting STRO-006 and dual‑payload PTK7 program STRO-227. Under its Astellas collaboration, a TROP2-targeted dual-payload iADC entered the clinic, triggering a $10 million milestone payment, while the company closed its luvelta program and stopped additional investment.
Affinity Asset Advisors and Michael Cho report ownership of 1,069,519 shares of Sutro Biopharma common stock, representing approximately 6.5% of the outstanding common stock as of March 31, 2026.
The filing states the percentage is calculated using 16,567,762 shares outstanding as of March 31, 2026, per the issuer's Definitive Proxy Statement filed April 22, 2026. The Reporting Persons hold sole voting and sole dispositive power over the reported shares.
Sutro Biopharma filed a Schedule 13G showing 946,829 shares of Common Stock beneficially owned by Point72-related reporting persons. The filing states this equals 5.7% of the class as of the close of business on April 30, 2026. The holdings are reported on behalf of Point72 Associates, with voting and dispositive power shared by Point72 Asset Management, Point72 Capital Advisors Inc., and Steven A. Cohen under a joint filing agreement.
Sutro Biopharma, Inc. is holding a virtual 2026 Annual Meeting of Shareholders on June 5, 2026. Stockholders will vote to elect three Class II directors (Jane Chung, Connie Matsui and James Panek) for three-year terms, ratify Ernst & Young LLP as auditor for 2026, and approve on an advisory basis the compensation of named executive officers.
Stockholders of record at the close of business on April 7, 2026, when 16,567,887 common shares were outstanding, may vote. The board is majority independent, with separate Chair and CEO roles and active Audit, Compensation, Nominating and Governance, and Science and Technology Committees. The proxy describes a pay-for-performance executive compensation program emphasizing equity awards and annual incentives, and notes prior Say-on-Pay support of 77.7% in 2025.