Arcus Biosciences And Gilead Discontinue Phase 3 STAR-221 Study In Cancer Due To Futility

(RTTNews) - Biopharmaceutical company Arcus Biosciences, Inc. (RCUS) announced Friday the discontinuation of the Phase 3 STAR-221 study, being conducted in partnership with Gilead Sciences, Inc. (GILD), due to futility. The study evaluated a domvanalimab-based combination in upper gastrointestinal cancers.

The decision is based on the recommendation from the Independent Data Monitoring Committee (IDMC) following its review of data from an event-driven, pre-specified interim analysis of overall survival (OS).

STAR-221 evaluated the anti-TIGIT antibody domvanalimab plus anti-PD-1 antibody zimberelimab and chemotherapy versus nivolumab plus chemotherapy as a first-line treatment for advanced gastric and esophageal cancers.

At the interim analysis, the domvanalimab-based combination did not improve OS relative to that of nivolumab plus chemotherapy. The safety profile for the domvanalimab-based combination was similar to that of nivolumab plus chemotherapy.

The company said it is now continuing to expand its development program for casdatifan, a potential best-in-class HIF-2a inhibitor with robust single-agent activity, and multiple data readouts are expected in 2026.

Arcus owns all of the rights to casdatifan outside of Japan and certain other Asian territories, which were optioned by Taiho Pharmaceutical Co., Ltd. in October 2025.

Arcus's early development efforts will focus on five programs targeting inflammatory and autoimmune (I&I) diseases; a small molecule targeting MRGPRX2 is expected to enter the clinic in 2026

With approximately $1 billion of cash and investmentsi, Arcus expects to be able to fund its planned operations until at least the second half of 2028.