On May 14, 2026 Sutro Biopharma, Inc. (Sutro or the Company) (NASDAQ: STRO), a clinical-stage oncology company pioneering site-specific and novel-format antibody drug conjugates (ADCs), reported its financial results for the first quarter of 2026 and recent business highlights.

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"During the first quarter, we continued to execute across our clinical and preclinical portfolio, positioning Sutro for key data readouts later this year," said Jane Chung, Sutro’s Chief Executive Officer. "Dose escalation is rapidly progressing in our Phase 1 trial of STRO-004, and we remain on track to report initial safety, pharmacokinetic and early activity data in mid-2026, which we believe will provide important insights into its clinical profile and our platform as a whole. This clinical momentum is reinforced by preclinical data we presented at the recent AACR (Free AACR Whitepaper) Annual Meeting, which highlighted the robust and consistent antitumor activity of STRO-004, as well as continued progress across our broader ADC pipeline."

"In parallel, we are advancing our next-generation ADC candidates, STRO-006, targeting ITGB6, and STRO-227, our first wholly-owned dual-payload ADC targeting PTK7, as we work toward IND submissions this year. We are also pleased to see our first partnered dual-payload iADC with Astellas entering the clinic, marking an important validation of our platform’s ability to generate differentiated multi-payload ADCs. With a strengthened balance sheet and continued disciplined execution, we believe we are well positioned to deliver meaningful progress across our programs in 2026."

Wholly-Owned Pipeline

STRO-004: Sutro continues to advance its ongoing first-in-human Phase 1 dose-escalation trial of STRO-004, a Tissue Factor (TF)-targeting ADC with a DAR8 Topo1 payload, in patients with advanced solid tumors. The Company expects to report initial clinical data in mid-2026, including safety and tolerability, pharmacokinetic exposure, and early activity data. In preclinical studies, STRO-004 demonstrated a favorable safety profile, including a highest non-severely toxic dose (HNSTD) of 50 mg/kg in non-human primates, supporting the clinical starting dose of 1 mg/kg.

STRO-006: Sutro’s next-generation, highly selective integrin β6 (ITGB6)-targeting ADC with a DAR8 Topo1 payload, designed for the treatment of multiple solid tumors. The program continues to advance toward clinical development, with an IND submission anticipated in 2026.

STRO-227: Sutro’s wholly-owned DAR10 dual-payload ADC targeting PTK7, combining MMAE (DAR2) and a Topo1 payload (DAR8) to enable complementary mechanisms of action within a single molecule. The program remains on track for IND submission in 2026 and represents a key component of Sutro’s strategy to expand its pipeline of novel-format dual-payload ADCs.

Next-Generation ADC Collaborations

Astellas: Two research and development programs are progressing under Sutro’s collaboration with Astellas focused on dual-payload immunostimulatory ADCs (iADCs).

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The first program, targeting TROP2, has entered the clinic and is actively dosing patients, resulting in a $10 million milestone payment received by Sutro in April 2026.
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The second program continues to progress in an IND-enabling toxicology study.

Medical Conferences

American Association for Cancer Research (AACR) (Free AACR Whitepaper), April 17-22, 2026, San Diego, California

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Sutro presented new preclinical data at AACR (Free AACR Whitepaper) from across its pipeline of ADC discovery programs, including an oral presentation on STRO-004. Among the highlights, STRO-004 demonstrated robust and consistent antitumor activity across multiple TF-expressing solid tumor PDX models, with improved anti-tumor activity versus benchmark ADCs. Additionally, STRO-006 and STRO-227 showed meaningful, dose-dependent antitumor activity across solid tumor models. More details can be found in the press release here.
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In addition to these presentations, Sutro’s strategic partner, Astellas Pharma, also reviewed preclinical results from its TROP2-targeted iADC program, ASP2998, at AACR (Free AACR Whitepaper). The oral presentation, titled "ASP2998, a TROP2-targeted immunostimulatory antibody-drug conjugate (iADC) with dual payloads, demonstrates potent efficacy and a favorable safety profile in nonclinical models," highlighted the progress in development of next-generation iADCs leveraging Sutro’s cell-free protein synthesis platform. ASP2998 is a first-in-class iADC that combines cytotoxic and immune-stimulatory mechanisms to enhance antitumor efficacy. Inclusion of a STING agonist augments the antitumor efficacy, immune activation and durable tumor immunity of ASP2998, supporting its superior activity over toxin-only anti-TROP2 ADCs. Preclinically, ASP2998 demonstrated a favorable safety profile, supporting a promising therapeutic index.
STRO-006 and STRO-227 show meaningful, dose-dependent antitumor activity across solid tumor models

Investor Conferences

Management will participate in the following upcoming healthcare investor conferences. When available, the webcasts of the presentations will be accessible through the News & Events page of the Investor Relations section of the Company’s website at www.sutrobio.com. Archived replays will be available for at least 30 days after the event.

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Jefferies Global Healthcare Conference (New York, NY • June 2-4)

Corporate Updates

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Sutro strengthened its cash position with an underwritten offering of 7,868,383 shares of its common stock at a price of $13.98 per share, resulting in gross proceeds of $110.0 million, before deducting underwriting discounts and commissions and other offering expenses. The Company’s cash runway is now expected into at least the second quarter of 2028, excluding additional anticipated milestones from our existing collaborations.
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The luvelta program has been closed and there will be no additional investment in the program. Sutro is not currently pursuing further business development opportunities for the program.

First Quarter 2026 Financial Highlights

Cash, Cash Equivalents and Marketable Securities

As of March 31, 2026, Sutro had cash, cash equivalents and marketable securities of $202.6 million, as compared to $141.4 million as of December 31, 2025.

Revenue

Revenue was $14.5 million for the quarter ended March 31, 2026, as compared to $17.4 million for the quarter ended March 31, 2025, with the 2026 amount related principally to the Astellas collaboration.

Research & Development (R&D) and General & Administrative (G&A) Expenses

Total R&D and G&A expenses for the quarter ended March 31, 2026 were $44.1 million, as compared to $64.9 million for the quarter ended March 31, 2025.

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H.C. Wainwright 4th Annual BioConnect Investor Conference (New York, NY • May 19)
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TD Cowen 7th Annual Oncology Innovation Summit (Virtual • May 26 – 27)

(Press release, Sutro Biopharma, MAY 14, 2026, View Source [SID1234665715])