Arcus Biosciences announced that it is discontinuing its global Phase 3 STAR‑221 study, a trial that compared domvanalimab plus chemotherapy with nivolumab plus chemotherapy in patients with advanced gastric and esophageal cancers. The decision follows a futility recommendation from the independent data monitoring committee after an interim overall‑survival analysis showed no benefit of the domvanalimab‑based regimen over the control arm. Safety data were comparable, with no new safety signals identified.
The cancellation removes a key late‑stage oncology asset from Arcus’s pipeline and signals a strategic pivot away from the TIGIT‑based approach that has faced stiff competition from larger players. Management said the company will reallocate resources to its top‑priority asset, casdatifan—a HIF‑2α inhibitor for renal cell carcinoma—and to emerging inflammation and immunology programs, including a small‑molecule targeting MRGPRX2 expected to enter the clinic in 2026. This shift reflects a focus on assets with clearer clinical trajectories and potentially higher commercial upside.
Arcus’s cash position remains robust, with approximately $1 billion in cash and investments that should fund operations through the second half of 2028. The reallocation of R&D spend is expected to accelerate data readouts for casdatifan, which has shown promising single‑agent activity in early studies and is anticipated to deliver multiple data points in 2026. The company’s financial runway mitigates short‑term valuation pressure from the trial discontinuation and supports continued investment in high‑potential programs.
"Patients in the domvanalimab arm derived the same benefit as those treated in the control arm, and there were no new safety concerns," said Dr. Richard Markus, Chief Medical Officer. "We are disappointed with this outcome and sincerely thank all those who participated in the study. We remain committed to advancing research for people living with cancer and immune‑related diseases." CEO Terry Rosen added, "The results from STAR‑221 are not what we had hoped for, and we have important work ahead to meet the needs of patients on our domvanalimab studies and also accelerate the casdatifan and I&I programs."
The TIGIT inhibitor landscape has intensified, with competitors such as Merck, Bristol‑Myers Squibb, and Gilead pursuing similar approaches. Arcus’s decision to exit STAR‑221 underscores the challenges of demonstrating survival benefit in this space. Casdatifan, positioned as a best‑in‑class HIF‑2α inhibitor, offers a differentiated mechanism against renal cell carcinoma and may compete with Merck’s Welireg. The company’s partnership with Gilead, which co‑developed domvanalimab and zimberelimab, will be affected by the trial’s termination, but the shift to casdatifan and I&I programs is expected to strengthen Arcus’s portfolio and market positioning.
Looking ahead, Arcus plans to deliver multiple data readouts for casdatifan in 2026, while the inflammation and immunology pipeline will progress toward first‑in‑human studies. The company’s strong cash position and focused R&D strategy aim to sustain momentum and create value for patients and investors alike.
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