Sutro Biopharma Announces First Patient Dosed in Phase 1 Trial of STRO-006, a Next-Generation ITGB6-Targeting ADC, in Advanced Solid Tumors

STRO-006 is Sutro’s second wholly owned antibody-drug conjugate to enter clinical testing in less than one year.

Rhea-AI Summary

Sutro Biopharma (NASDAQ: STRO) has dosed the first patient in its Phase 1 trial of STRO-006 for advanced solid tumors. STRO-006 targets integrin β6 (ITGB6) and is an antibody-drug conjugate, which links an antibody to a cancer drug. It is Sutro’s second wholly owned antibody-drug conjugate to enter clinical testing in less than one year.

The open-label, multicenter trial will assess safety, pharmacokinetics—how the body processes the drug—and preliminary anti-tumor activity in adults with advanced or metastatic solid tumors. Dose escalation will enroll patients with ITGB6-expressing tumor types, including lung, head and neck, gastrointestinal, endometrial, urothelial and breast cancers. Sutro reported sustained anti-tumor activity with minimal on-target toxicity in preclinical models and expects initial clinical data in the second half of 2027.

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Positive

• Moderate pointFirst patient dosed advances wholly owned STRO-006 into Phase 1 clinical testing.
• Minor point. Forward-looking: it has not happened yet and may not happen.Initial clinical data are expected by Sutro in the second half of 2027.
• Minor pointPreclinical models showed sustained anti-tumor activity with minimal on-target toxicity, Sutro reported.
• Minor pointNon-human primate tolerability at doses up to 30 mg/kg supported the trial’s starting dose.

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• None.

Key Figures

Initial clinical data timing: Second half of 2027 Starting dose: 1.5 mg/kg Non-human-primate tolerability dose: Up to 30 mg/kg +1 more

Initial clinical data timing

Second half of 2027

Expected for STRO-006

Starting dose

1.5 mg/kg

Beginning dose level in the Phase 1 trial

Non-human-primate tolerability dose

Up to 30 mg/kg

Tolerability observed in non-human primates

Drug-to-antibody ratio

8 (DAR8)

STRO-006

Key Terms

antibody drug conjugates, drug-to-antibody ratio, pharmacokinetics, open-label, +1 more

5 terms

antibody drug conjugates medical

"a clinical-stage oncology company pioneering site-specific and novel-format antibody drug conjugates"

Antibody drug conjugates are targeted medicines that combine an antibody, which seeks out specific markers on diseased cells, with a powerful drug that is released only when the antibody binds its target. Think of it as a guided missile that delivers a toxic payload directly to its target, reducing damage to healthy cells; investors watch them because successful ADCs can offer high-value, niche treatments and drive strong revenue and patent-based protection for developers.

drug-to-antibody ratio technical

"with a drug-to-antibody ratio of 8 (DAR8)"

Drug-to-antibody ratio is the average number of small drug molecules attached to each antibody in an antibody-drug conjugate, a targeted cancer treatment. It matters to investors because this number affects how potent, stable and safe the medicine is, as well as how consistently it can be manufactured; think of it like the number of batteries in a flashlight — more can mean brighter effect but also more weight, complexity and risk.

pharmacokinetics medical

"evaluate the safety, pharmacokinetics and preliminary anti-tumor activity"

Pharmacokinetics is the study of how a substance, such as a drug or chemical, moves through and is processed by the body over time. It tracks how it is absorbed, distributed, broken down, and eventually eliminated. For investors, understanding pharmacokinetics helps gauge the effectiveness, safety, and potential risks of new medications or treatments, which can influence a company’s success and valuation in the healthcare industry.

open-label medical

"The Phase 1, open-label, multicenter trial"

Open-label describes a situation where everyone involved in a study or process knows the full details, such as who is receiving a treatment or intervention. For investors, understanding whether a project or product is open-label helps gauge the level of transparency and potential biases, influencing trust and decision-making. It’s like knowing whether a test or experiment is conducted openly or behind closed doors.

dose-escalation medical

"The dose-escalation portion will enroll patients"

Dose-escalation is the part of an early-stage clinical trial where researchers gradually increase a drug’s dose in small groups of participants to find the safest and most effective amount. Think of it like turning up the volume slowly to find the sweet spot: investors watch these results closely because they reveal safety risks, potential effectiveness, and how quickly a drug can move to later trials or approval, all of which affect the development timeline and commercial prospects.

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— STRO-006 is Sutro’s second wholly-owned ADC to enter the clinic in less than one year —

      — Initial clinical data expected in the second half of 2027 —

SOUTH SAN FRANCISCO, Calif., Oct. 21, 2026 (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), today announced that the first patient has been dosed in its Phase 1 trial of STRO-006 in patients with a range of solid tumors. STRO-006 is the Company’s potential best-in-class integrin β6 (ITGB6)-targeting exatecan ADC with a drug-to-antibody ratio of 8 (DAR8), engineered for optimized pharmacokinetics, tolerability and a differentiated therapeutic index.

“Dosing the first patient with STRO-006 marks our second ADC to enter the clinic in less than a year and reflects the Sutro team’s exceptional execution of our pipeline strategy,” said Jane Chung, Chief Executive Officer of Sutro. “ITGB6 is difficult to target due to complex biology and is expressed across a broad range of tumors with high unmet need, including non-small cell lung and head and neck cancers. In preclinical models, STRO-006 demonstrated potent, sustained anti-tumor activity with minimal on-target toxicity, supporting our belief that Sutro’s advanced design capabilities can widen the therapeutic index and deliver a differentiated safety and efficacy profile. We look forward to advancing STRO-006 in the clinic and evaluating its potential to benefit patients.”

The Phase 1, open-label, multicenter trial is designed to evaluate the safety, pharmacokinetics and preliminary anti-tumor activity of STRO-006 in adults with advanced or metastatic solid tumors. The dose-escalation portion will enroll patients with ITGB6-expressing tumor types, including head and neck cancer, non-small cell lung cancer, esophageal/gastric cancer, colorectal cancer, endometrial cancer, urothelial cancer and breast cancer. The trial will evaluate STRO-006 across ascending dose levels beginning at 1.5 mg/kg. This starting dose is enabled by Sutro’s precise design capabilities and supported by the tolerability observed in non-human primates at doses up to 30 mg/kg.

More information can be found at:  https://clinicaltrials.gov/study/NCT07807345

About STRO-006

STRO-006 is Sutro’s next-generation DAR8 ADC targeting integrin β6 (ITGB6), a tumor-associated antigen expressed across several high-prevalence solid tumors. This candidate delivers a potent exatecan payload attached via a site-specific β-glucuronidase cleavable linker to a high-affinity antibody that binds to ITGB6 without disrupting TGFβ signaling. STRO-006 is designed to deliver a wider therapeutic index than conventional ADCs by enhancing selectivity, stability, and pharmacokinetics. In preclinical studies, STRO-006 demonstrated strong and durable anti-tumor activity. STRO-006 is currently being evaluated in a Phase 1 trial in patients with a range of ITGB6-expressing solid tumors.

About Sutro Biopharma

Sutro Biopharma, Inc. is a clinical-stage biotechnology company 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, including initial clinical data from the Phase 1 trial of STRO-006; potential benefits, efficacy and safety profile of the Company’s product candidates, including STRO-006, and platform; potential market opportunities for the Company’s product candidates; and the positioning of the Company’s product candidates in the competitive landscape. 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 are 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, including the risk that results of preclinical studies may not be predictive of results in clinical trials and that undesirable side effects could result in the delay, suspension or termination of clinical trials, the Company’s ability to fund development activities and achieve development goals, the Company’s ability to protect intellectual property, the Company’s commercial collaborations with third parties, the impact of health pandemics, tariffs, regional geopolitical conflicts, changes in interest rates, inflation, potential uncertainty with respect to the debt ceiling and government shutdowns, 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

FAQ

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What is Sutro Biopharma’s STRO-006 Phase 1 trial evaluating?

The trial evaluates safety, pharmacokinetics and preliminary anti-tumor activity in adults with advanced or metastatic solid tumors. STRO-006 targets ITGB6, and the open-label, multicenter study will enroll patients with ITGB6-expressing tumor types during dose escalation.

When does Sutro expect initial STRO-006 clinical data?

Sutro expects initial clinical data in the second half of 2027. The first patient has been dosed in the Phase 1 trial.

What starting dose is being used in Sutro’s STRO-006 trial?

The trial will evaluate ascending dose levels beginning at 1.5 mg/kg. The starting dose is supported by tolerability observed in non-human primates at doses up to 30 mg/kg.