Sutro Biopharma (STRO) R&D Day 2025 summary

Pipeline overview and program updates

• Advancing a diversified ADC pipeline: STRO-004 (TF-targeting, in Phase 1), STRO-006 (integrin beta-6, IND planned for 2026), and STRO-227 (PTK7 dual-payload, IND planned for 2026/2027), with multiple programs progressing in parallel.

• Proprietary platform enables both single- and dual-payload ADCs, targeting complex and resistant tumors with improved safety and efficacy.

• Dual-payload ADCs, including collaborations with Astellas on iADC programs, are positioned to address resistance and expand efficacy in solid tumors, with the first clinical entry expected in early 2026.

• STRO-004 re-entered the clinic with first patient enrollment by year-end and initial data expected mid-2026.

Clinical trial data and development milestones

• STRO-004 Phase 1 basket trial is ongoing, enrolling patients with TF-expressing solid tumors; early data show promising anti-tumor activity and a wide therapeutic window.

• STRO-004 demonstrated superior preclinical efficacy and tolerability compared to Tivdak, with reduced bleeding risk and higher HNSTD.

• STRO-006 showed superior safety and efficacy over competitor ADCs, with a 71% ORR in head and neck PDX models and no ILD or neutropenia in preclinical studies; IND filing planned for 2026.

• STRO-227 (PTK7 dual-payload) demonstrated durable responses in resistant tumor models and is advancing toward IND filing in late 2026/2027.

• iADC programs show 100% complete response in preclinical HER2 models and favorable tolerability in NHP studies.

R&D strategy and innovation priorities

• Strategic reset in 2025 included right-sizing the team, externalizing manufacturing, and focusing on rapid, parallel program advancement.

• Platform enables precise control of ADC design, including tunable drug-to-antibody ratios, dual payloads, and site-selective conjugation to optimize efficacy and safety.

• Emphasis on validated targets, synergistic payload combinations, and immunostimulatory ADCs to de-risk development and maximize clinical impact.

• Focus on expanding the therapeutic window and minimizing toxicity through Fc-silent antibodies, optimized linkers, and high DAR exatecan payloads.