STRO-004

May 14, 2026: Sutro Biopharma, Inc. (NASDAQ: STRO) reported Q1 2026 results and provided pipeline catalysts.

STRO-004 (Tissue Factor ADC; DAR8 Topo1 payload): Ongoing first-in-human Phase 1 dose-escalation trial in advanced solid tumors is “rapidly progressing.” Sutro expects to report initial clinical data (safety/tolerability, pharmacokinetics, and early activity) in mid-2026. Preclinical work cited includes non-human primate HNSTD of 50 mg/kg supporting a 1 mg/kg clinical starting dose; AACR 2026 data showed antitumor activity in TF-expressing PDX models and improved activity vs benchmark ADCs.

STRO-006 (ITGB6 ADC; DAR8 Topo1): Advancing toward clinical development with an IND submission anticipated in 2026; AACR preclinical data showed dose-dependent antitumor activity in solid tumor models.

STRO-227 (PTK7 dual-payload ADC; DAR10 with MMAE and Topo1): IND submission planned in 2026; AACR preclinical data showed dose-dependent antitumor activity.

Astellas collaboration (dual-payload iADCs): The first program (TROP2-targeted) has entered the clinic and is dosing patients; Sutro received a $10 million milestone in April 2026. A second program is in IND-enabling toxicology. Astellas presented AACR preclinical results for ASP2998 (TROP2 iADC with STING agonist).

Corporate update: Sutro closed the “luvelta” program and will not invest further. Cash was $202.6M as of March 31, 2026; a recent $110.0M gross equity raise extends runway into at least Q2 2028.