Arcus and Gilead's 3-Star Phase Study Fails to Demonstrate Efficacy in Advanced Gastrointestinal Cancers

Arcus Biosciences has ended its Phase 3 clinical trial—known as 3-star—after determining the experimental treatment combination did not meet efficacy targets in upper gastrointestinal cancer patients. The decision came following guidance from an independent data monitoring board that reviewed interim survival data from the trial.

The discontinued 3-star study was evaluating whether a combination of domvanalimab (an anti-TIGIT agent) paired with zimberelimab (anti-PD-1 antibody) plus chemotherapy could outperform the existing standard of nivolumab combined with chemotherapy in patients with advanced gastric and esophageal cancers receiving first-line treatment. At the interim analysis checkpoint, the experimental combination failed to show a survival advantage over the control regimen. Both treatment approaches demonstrated comparable safety profiles during the trial.

This development represents a setback for the partnership between Arcus and Gilead Sciences but does not derail the companies’ broader pipeline. Arcus is now prioritizing expansion of its casdatifan program—a next-generation HIF-2α inhibitor demonstrating robust single-agent activity. The company expects multiple clinical readouts for this candidate in 2026. Additionally, Arcus has licensed casdatifan development rights in Japan and select Asian markets to Taiho Pharmaceutical, a deal finalized in October 2025. Arcus retains exclusive rights to the compound in other regions.

Beyond oncology, Arcus is advancing five early-stage programs targeting inflammatory and autoimmune conditions, with a novel MRGPRX2 inhibitor expected to enter clinical testing next year. With approximately $1 billion in available capital and investments, the company projects sufficient funding to sustain operations through at least mid-2028, providing a strategic runway for its diversified development efforts.