Sutro Biopharma, Inc.

The company is a clinical stage oncology company that develops site-specific and novel-format antibody drug conjugates (ADCs). It uses its proprietary integrated cell-free protein synthesis platform, XpressCF®, and its site-specific conjugation platform, XpressCF+®, to design and develop therapeutics. These therapeutics include ADCs, bispecific ADCs, immunostimulatory ADCs (iADCs), and dual-payload ADCs (dpADCs), primarily targeting clinically validated targets where current treatments are suboptimal. The company's highest priority wholly-owned product candidate is STRO-004, a single homogeneous ADC directed against tissue factor (TF), which is being developed for the treatment of solid tumors. An Investigational New Drug (IND) application for STRO-004 was filed and cleared in October 2025, and a Phase 1 trial began in November 2025. This open-label, multicenter trial evaluates the safety, pharmacokinetics, and preliminary anti-tumor activity of STRO-004 in patients with advanced TF-expressing solid tumors, including non-small cell lung cancer, head and neck squamous cell carcinoma, cervical cancer, colorectal cancer, pancreatic ductal adenocarcinoma, endometrial cancer, and bladder cancer. The dose-escalation phase includes multiple cohorts with ascending dose levels. Dosing of patients in dose level 2 was completed in February 2026, and dosing in the dose level 3 cohort began in February 2026. The company's preclinical assets include STRO-227 and STRO-006.