On August 12, 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 second quarter ended June 30, 2026 and recent business highlights. Sutro also provided data showing a favorable tolerability profile and early signals of clinical activity from its ongoing Phase 1 study of STRO-004, the Company’s potential best-in-class Tissue Factor (TF)-targeting DAR8 exatecan ADC, in heavily pretreated patients with advanced solid tumors.
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"During the second quarter, we continued to execute swiftly across our next-generation ADC portfolio, highlighted by encouraging early clinical data from our ongoing Phase 1 study of STRO-004, having rapidly enrolled our initial dose escalation cohorts in just seven months and now optimizing our go-forward dose," said Jane Chung, Sutro’s Chief Executive Officer. "We have observed early clinical responses alongside favorable safety, tolerability, and a differentiated pharmacokinetic (PK) profile in patients with few remaining treatment options. The favorable tolerability profile and wider therapeutic index of our DAR8 exatecan ADC allows us to dose higher than other TF-targeting ADCs. These findings strengthen our confidence in STRO-004’s potential to deliver meaningful clinical benefit and provide the opportunity to safely combine with other therapies, while further validating our proprietary ADC platform."
"Additionally, we are excited to enter the clinic with STRO-006 in the near future, our second clinical program in less than a year, reflecting the continued acceleration of our pipeline strategy. We also look forward to advancing STRO-227, our first wholly-owned dual-payload ADC, toward IND submission later this year, joining our partner Astellas’ dual-payload iADC programs in the clinic. Our progress this quarter underscores the continued advancement of our portfolio and our commitment to delivering differentiated therapies for patients while creating long-term value for shareholders."
Wholly-Owned Pipeline
STRO-004 Early Safety and Signals of Clinical Activity Highlights:
Dose escalation continues with strong execution, with dose levels 1–5 mg/kg (n=49) enrolled faster than expected. The study, called STRIVE-01, is currently optimizing between doses of 4 and 5 mg/kg, and the maximum tolerated dose has not yet been defined. This US-only based trial, which began in November 2025, includes heavily pretreated patients (median of 3 prior lines of therapy [range 1–7]) across eight tumor types unselected for TF expression. In pancreatic and colorectal cancer patients, 100% of patients received one or more prior irinotecan-containing regimens, which has been associated with reduced activity of topoisomerase 1 inhibitor payloads. Key observations as of the data cutoff date of July 24, 2026 include:
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Multiple responses, including confirmed and ongoing unconfirmed partial responses, across three tumor types in RECIST-evaluable patients to date; including pancreatic cancer, head and neck cancer, and non-small cell lung cancer at dose levels 3-4 mg/kg
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Favorable tolerability profile, with mostly low-grade adverse events (AEs) observed. Overall discontinuation rate due to AEs was low at 6%.
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All-grade treatment related adverse events (TRAEs) >15% were nausea (33%), fatigue (29%), and anemia (18%)
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Other TRAEs of note that occurred in >5% of patients included:
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Hematologic events: Neutrophil count decreased (6%), platelet count decreased (6%)
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On-target TF-related events: Epistaxis (12%), stomatitis (10%), mucosal inflammation (8%), conjunctivitis (8%), dry eye (7%); these events were predominantly grade 1-2
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Grade 3+ events: Anemia (14%); all grade 3
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DLTs occurred only at the highest dose level tested (5 mg/kg), and appeared to be largely driven by target-related toxicity, resulting in dose reduction but no study drug discontinuations
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Predictable PK in patients, consistent with preclinical data, demonstrating dose-proportional ADC exposures at all doses, with no evidence of Target Mediated Drug Disposition
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STRO-004 has a half-life of nearly seven days, preserving 98% DAR8 configuration, while free exatecan concentration remains low, delayed, and formation-limited
"We are encouraged by the emerging STRO-004 clinical PK profile, which demonstrate the stability of our ADC construct and validate the design principles of our platform," said Hans-Peter Gerber, Ph.D., Sutro’s Chief Scientific Officer. "Compared with conventional DAR8 exatecan ADCs, STRO-004 delivered 25-50% more ADC exposure with at least 50% less circulating payload concentration, allowing us to dose at the highest end of the dosing range for the class. We observed comparable PK with STRO-006 (Topo1i) and our dual payload ADC STRO-227 (Topo1i x MMAE) in preclinical experiments, which gives us confidence in the potential of our advanced design capabilities to widen the therapeutic index across our ADC pipeline."
The next STRIVE-01 study update is targeted for the first half of 2027. Initiation of expansion cohorts is planned for the first half of 2027.
STRO-006: Sutro’s next-generation, highly selective integrin β6 (ITGB6)-targeting ADC with a DAR8 exatecan payload, is designed for the treatment of multiple solid tumors. The Company expects to initiate a Phase 1 clinical trial in the third quarter of 2026.
STRO-227: Sutro’s wholly-owned DAR10 dual-payload ADC targeting PTK7, consisting of MMAE (DAR2) and exatecan (DAR8) payloads 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).
The first program, which targets TROP2, continues to actively dose patients, resulting in a $10 million milestone payment received by Sutro in April 2026.
The second program continues to progress under the collaboration, and based on current development timelines, Sutro expects Astellas to enter the clinic by the end of 2026.
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.
Wells Fargo 21st Annual Healthcare Conference (Boston, MA • September 8-10)
Cantor Global Healthcare Conference (New York, NY • September 9-11)
H.C. Wainwright 28th Annual Global Investment Conference (New York, NY • September 14-16)
Second Quarter 2026 Financial Highlights
Cash, Cash Equivalents and Marketable Securities
As of June 30, 2026, Sutro had cash, cash equivalents and marketable securities of $164.3 million, as compared to $202.6 million as of March 31, 2026.
Revenue
Revenue was $9.8 million for the quarter ended June 30, 2026, as compared to $63.7 million for the quarter ended June 30, 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 June 30, 2026 were $39.5 million, as compared to $48.7 million for the quarter ended June 30, 2025.
(Press release, Sutro Biopharma, AUG 12, 2026, View Source [SID1234670008])