On November 12, 2025 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 to host a virtual R&D Day 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.

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"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 View Source An archived replay of the webcast will be available on the Company’s website following the event.

(Press release, Sutro Biopharma, NOV 12, 2025, View Source [SID1234659844])