Sutro Biopharma Inc

Sutro Biopharma is a clinical-stage biotechnology company focused on developing next-generation antibody-drug conjugates (ADCs) for oncology. The company utilizes a proprietary cell-free protein synthesis platform that enables site-specific conjugation and precise payload placement, producing both single-payload and dual-payload ADCs designed to improve drug exposure, reduce side effects, and expand treatable tumor types. Sutro's wholly-owned pipeline includes STRO-004 (a Tissue Factor-targeting DAR8 exatecan ADC in Phase 1 for advanced solid tumors), STRO-006 (an integrin β6-targeting exatecan ADC approaching Phase 1), and STRO-227 (a PTK7-targeting dual-payload ADC combining exatecan and MMAE approaching IND submission). The company also has partnered programs, including a collaboration with Astellas Pharma on dual-payload immunostimulatory ADCs (iADCs) targeting TROP2 and an undisclosed target, and vaccine conjugate programs (VAX-31 and VAX-24) for invasive pneumococcal disease. Sutro's platform differentiates through non-natural amino acid incorporation, click chemistry conjugation, and proprietary β-glucuronide linkers that collectively enable high drug-to-antibody ratios, stable pharmacokinetics, and reduced systemic toxicity. The company trades on NASDAQ under the ticker STRO. Updated Aug 12, 2026