Gilead Sciences and Arcus Biosciences announced that they are terminating the Phase 3 STAR‑221 study of domvanalimab, an anti‑TIGIT antibody, combined with zimberelimab, an anti‑PD‑1 antibody, and standard chemotherapy in patients with advanced gastric or esophageal squamous‑cell cancer.
The decision follows an interim analysis by the independent data monitoring committee that found the combination did not improve overall survival compared with the control arm of nivolumab plus chemotherapy. Safety data were comparable between the two arms, with no new adverse events reported.
For Gilead, the halt signals a recalibration of its oncology portfolio. The company has invested heavily in upper‑gastrointestinal indications through acquisitions and internal development, but the failure of this late‑stage program will shift resources toward other candidates, such as its immuno‑oncology assets in earlier lines of therapy. The impact on Gilead’s earnings is expected to be modest, as its core HIV and liver‑disease businesses provide a stable revenue base.
Arcus faces a more pronounced setback. The company’s domvanalimab program was a flagship asset, and its discontinuation will prompt a pivot to other pipeline priorities, notably casdatifan, a HIF‑2α inhibitor, and its inflammatory‑disease programs. With roughly $1 billion in cash and investments, Arcus has runway through the second half of 2028, but the loss of a potential blockbuster will affect its long‑term growth prospects.
The anti‑TIGIT field remains competitive, and the STAR‑221 failure is particularly striking given the positive overall‑survival results from the Phase 2 EDGE‑Gastric study in a similar patient population. The contrast underscores the challenges of translating early‑stage signals into late‑stage efficacy and may influence investor confidence in the TIGIT class.
Richard Markus, Arcus’s chief medical officer, said the company is “disappointed” but remains committed to advancing research for patients with cancer and immune‑related diseases. Gilead’s leadership has emphasized continued focus on cost discipline and strategic investments, signaling confidence in its broader oncology strategy despite this setback.
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