Sutro Biopharma Doses Third STRO-004 Cohort, Raises $110M to Extend Cash to 2Q 2028
Sutro completed dosing three cohorts in its Phase 1 STRO-004 trial and expects initial mid-2026 data; it also advanced its dual-payload STRO-227 toward an IND in 2026. It held $141.4 million in cash and raised $110 million, funding operations into 2Q 2028 as its Astellas-partnered iADC program began dosing and triggered a $10 million milestone.
1. Phase 1 STRO-004 Progress
Sutro completed dosing of three cohorts in its first-in-human Phase 1 study evaluating STRO-004, an exatecan-based Tissue Factor ADC with DAR8 Topo1 payload. The company expects initial safety, pharmacokinetic and early activity readouts by mid-2026, supported by a favorable preclinical safety profile at 50 mg/kg HNSTD.
2. Advancement of STRO-227 and STRO-006
Sutro accelerated its wholly owned dual-payload ADC STRO-227, targeting PTK7 with MMAE (DAR2) and Topo1 (DAR8) payloads, toward an IND filing in 2026. Its selective ITGB6 ADC STRO-006 is on track to enter clinical development in 2026 for multiple solid tumors.
3. Astellas Partnership and Milestones
The Astellas-partnered immunostimulatory ADC program targeting TROP2 entered the clinic and began patient dosing, triggering a $10 million milestone expected in the second quarter of 2026. A second dual-payload iADC program advanced to IND-enabling toxicology in late 2025, earning a $7.5 million payment.
4. Financial Position and Cash Runway
As of December 31, 2025, Sutro held $141.4 million in cash and equivalents and completed a $110 million common stock offering at $13.98 per share. This financing extends the company’s cash runway into at least the second quarter of 2028, excluding future collaboration milestones.