SUTRO BIOPHARMA, INC.

We are a clinical stage oncology company developing site-specific and novel-format antibody drug conjugates, or ADCs, enabled by our proprietary integrated cell-free protein synthesis platform, XpressCF , and our site-specific conjugation platform, XpressCF+ . We aim to design and develop therapeutics using the most relevant and potent modalities, including ADCs, bispecific ADCs, immunostimulatory ADCs, or iADCs, and dual-payload ADCs, or dpADCs. Our molecules are directed primarily against clinically validated targets where the current standard of care is suboptimal. We believe that our platform allows us to accelerate the discovery and development of potential first-in-class and/or best-in-class molecules by enabling the rapid and systematic evaluation of protein structure-activity relationships to create optimized homogeneous product candidates. Our mission is to transform the lives of patients by creating medicines with improved therapeutic profiles for areas of unmet need. Our highest priority wholly-owned product candidate is STRO-004, a single homogeneous ADC directed against tissue factor, or TF, which we are developing for the treatment of solid tumors. We believe STRO-004 has the potential to be a best-in-class ADC targeting TF. In preclinical studies, STRO-004 has demonstrated potent antitumor activity and the potential for a differentiated safety profile. We filed an IND and received IND clearance for STRO-004 in October 2025, and initiated a Phase 1 trial in November 2025. We expect to report initial data from this trail in mid-2026.