Sutro Biopharma Highlights Next-Generation ADC Innovation at Virtual R&D Day

- Company has initiated Phase 1 study with STRO-004, its potential best-in-class Tissue Factor ADC -

- Sutro has selected PTK7 as the target for its initial dual-payload candidate, STRO-227 -

- Investor webcast today at 7:00AM PT / 10:00AM ET -

SOUTH SAN FRANCISCO, Calif., Nov. 12, 2025 (GLOBE NEWSWIRE) -- Sutro Biopharma, Inc. (Sutro or the Company) (NASDAQ: STRO), a clinical stage oncology company pioneering site-specific and novel-format antibody drug conjugates (ADCs), is hosting a virtual R&D Day today highlighting the details of its platform innovation and next-generation ADC pipeline. The presentation will include an overview of Sutro’s near- and long-term priorities, beginning with STRO-004, its potential best-in-class Tissue Factor ADC, which has now entered clinical development. The Company will also provide details on its dual-payload ADC programs, uniquely enabled by its proprietary cell-free platform, and reveal STRO-227, its first dual-payload candidate designed to target PTK7.

“The programs we are advancing showcase our platform’s unique potential to meaningfully expand the therapeutic window and address some of the most persistent challenges with conventional ADCs,” said Jane Chung, Sutro’s Chief Executive Officer. “With STRO-004 entering the clinic and our dual-payload programs accelerating, we are positioned to deliver ADCs that combine optimized target engagement, differentiated design, and industry-leading pharmacokinetics to enable deeper and more durable responses to redefine what is possible for cancer care.”

Ms. Chung continued: “The selection of PTK7 for our initial dual-payload program underscores our strategy to address difficult-to-treat solid tumors where standard approaches have been insufficient. Additionally, through strategic collaborations including our partnership with Astellas, we continue to broaden the impact of our ADC technology and advance novel payload combinations to deliver therapies with the potential to transform the standard of care to patients.”

The event will feature presentations by key members of Sutro’s senior management team and Anthony Tolcher, M.D., FRCPC, FACP, a medical oncologist and founder and head of NEXT Oncology. Sutro management will participate in a Q&A session at the end of the presentation.

Next-Generation ADC Innovation
Sutro’s platform is designed to optimize every component of an ADC—the antibody, linker, and payload—rather than focusing on one or two elements in isolation. This holistic control is enabled by the Company’s cell-free technology, which allows unparalleled flexibility in designing ADCs and the potential to dose higher due to optimized safety and efficacy, even in complex biological settings. In addition, the platform enables sophisticated dual-payload combinations, enabling therapies that could redefine the standard-of-care.

Program Highlights and Near-Term Pipeline Milestones

Single-payload ADC Programs
Single-payload programs will establish Sutro’s foundation by tackling hard-to-reach, complex targets.

STRO-004: A potential best-in-class Tissue Factor (TF) targeting ADC, STRO-004, has entered clinical trials following recent IND clearance from the U.S. Food and Drug Administration (FDA). In preclinical TF-expressing models of head and neck squamous cell carcinoma, non-small cell lung cancer, colorectal cancer, and pancreatic cancer, STRO-004 showed promising anti-tumor activity. Combined with a highest non-severely toxic dose of 50 mg/kg in non-human primate studies, STRO-004 is anticipated to meaningfully widen the therapeutic window versus conventional ADCs to address a wide range of tumors of unmet need.
STRO-006: A potential best-in-class, highly selective integrin β6 (ITGB6) targeting ADC, STRO-006, has demonstrated a superior pharmacokinetic profile compared to the current ITGB6-targeting ADC in Phase 3 development. Additionally, STRO-006 demonstrated encouraging anti-tumor activity and duration of response in preclinical models. STRO-006 is expected to enter clinical development in 2026 for the treatment of multiple solid tumors.

Dual-Payload ADC Program
Sutro’s dual-payload ADCs are designed to overcome resistance, delay progression, and potentially set a new standard-of-care by unlocking durable efficacy.

STRO-227: Sutro has selected tyrosine-protein kinase-like 7 (PTK7) as the target for its initial dual-payload candidate. PTK7 is overexpressed in many different cancers, including breast, lung, ovarian and colorectal cancer. The Company is working to accelerate its dual-payload ADC program, with an IND submission now targeted for 2026/2027.

Summary of Pipeline Milestones

STRO-004: Phase 1 study ongoing; initial data expected mid-2026
STRO-006: IND submission targeted for 2026
STRO-227: IND submission targeted for 2026/2027

Next-Generation ADC Collaborations
Research and development programs are progressing under Sutro’s collaboration, with Astellas focused on dual-payload immunostimulatory ADCs (iADCs). The first iADC program is expected to enter the clinic in early 2026.

Webcast Information:
To access the live audio webcast beginning at 7:00AM PT / 10:00AM ET, please go to https://ir.sutrobio.com/news-events/ir-calendar. An archived replay of the webcast will be available on the Company’s website following the event.

About Sutro Biopharma
Sutro Biopharma, Inc. is advancing a next-generation antibody-drug conjugate (ADC) platform designed to deliver single- and dual-payload ADCs that enable meaningful breakthroughs for patients with cancer. By fully optimizing the antibody, linker, and payload, Sutro’s cell-free platform produces ADCs that are engineered to improve drug exposure, reduce side effects, and expand the range of treatable tumor types. With unique capabilities in dual-payload ADCs, Sutro aims to overcome treatment resistance and redefine what’s possible in cancer therapy. The Company’s pipeline of single- and dual-payload ADCs targets large oncology markets with limited treatment options and significant need for improved therapies.

For more information, follow Sutro on social media @Sutrobio or visit www.sutrobio.com.

Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995, including, but not limited to, anticipated preclinical and clinical development activities; timing of announcements of IND submissions, trial initiation, clinical results, 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 and the timing and receipt of anticipated future milestone payments. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. Although the Company believes that the expectations reflected in such forward-looking statements are reasonable, the Company cannot guarantee future events, results, actions, levels of activity, performance or achievements, and the timing and results of biotechnology development and potential regulatory approval is inherently uncertain. Forward-looking statements are subject to risks and uncertainties that may cause the Company’s actual activities or results to differ significantly from those expressed in any forward-looking statement, including risks and uncertainties related to the Company’s ability to advance its product candidates, the receipt and timing of potential regulatory designations, approvals and commercialization of product candidates, the market size for the Company’s product candidates to be smaller than anticipated, clinical trial sites, supply chain and manufacturing facilities, the Company’s ability to obtain, maintain and recognize the benefits of certain designations received by product candidates, the timing and results of preclinical and clinical trials, the Company’s ability to fund development activities and achieve development goals, the Company’s ability to protect intellectual property, and the Company’s commercial collaborations with third parties and other risks and uncertainties described under the heading “Risk Factors” in documents the Company files from time to time with the Securities and Exchange Commission. These forward-looking statements speak only as of the date of this press release, and the Company undertakes no obligation to revise or update any forward-looking statements to reflect events or circumstances after the date hereof.

Investor Contact
Emily White
Sutro Biopharma
(650) 823-7681
ewhite@sutrobio.com

Media Contact
Amy Bonanno
Lyra Strategic Advisory
abonanno@lyraadvisory.com

Source: Sutro Biopharma, Inc.

Released November 12, 2025