On December 12, 2025 Gilead Sciences and Arcus Biosciences reported the discontinuation of the Phase 3 STAR-221 study evaluating the anti-TIGIT antibody domvanalimab plus anti-PD-1 antibody zimberelimab and chemotherapy versus nivolumab plus chemotherapy as first-line treatment for HER2-negative advanced gastric and esophageal cancers. The decision is based on the recommendation from the Independent Data Monitoring Committee (IDMC) following their review of data from a pre-specified interim analysis of overall survival (OS).
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In the pre-specified interim analysis, the combination of domvanalimab plus zimberelimab and chemotherapy did not improve OS relative to nivolumab plus chemotherapy, the standard of care, and there was low likelihood of achieving a positive survival benefit with further follow-up. The safety profile for the combination of domvanalimab plus zimberelimab and chemotherapy was consistent with the control arm, nivolumab plus chemotherapy, and there were no new safety findings.
The companies are informing regulators and communicating with investigators for the STAR-221 and the Phase 2 EDGE-Gastric studies to determine appropriate next steps for patients. The companies are conducting a detailed analysis to understand these results, which will be published in the future.
"These results offer valuable insights into the complexity of treating advanced gastroesophageal cancers," said Dietmar Berger, MD, PhD, Chief Medical Officer at Gilead Sciences. "We will collaborate closely to understand the full scope of the data and engage key stakeholders in determining the appropriate next steps. We are deeply grateful to the patients, families, and healthcare professionals who participated in the STAR-221 study and contributed to this important work."
Currently, there are no changes to other ongoing domvanalimab studies beyond the upper gastrointestinal (GI) program. Arcus and Gilead will share further guidance as it becomes available.
Domvanalimab and zimberelimab are investigational molecules, and neither Gilead nor Arcus has received approval from any regulatory authority for any use globally, and their safety and efficacy have not been established.
(Press release, Gilead Sciences, DEC 12, 2025, View Source [SID1234661411])