Arcus Biosciences, Inc. 8-K

What Happened

• On April 20, 2026, Arcus Biosciences announced it will discontinue the Phase 3 STAR-121 study, run in collaboration with Gilead Sciences, after the Independent Data Monitoring Committee (IDMC) recommended stopping the trial for futility following a pre-planned futility analysis. STAR-121 compared the anti‑TIGIT antibody domvanalimab plus anti‑PD‑1 zimberelimab and chemotherapy against pembrolizumab plus chemotherapy as first‑line treatment for metastatic non‑small cell lung cancer (NSCLC). Safety was not assessed at the futility analysis, and the IDMC reported no new safety issues during regular reviews. The company also will discontinue the Phase 2 EDGE‑Lung study. Gilead is communicating with investigators about next steps for patients.

Key Details

• Announcement date: April 20, 2026.
• Trial stopped for futility based on IDMC recommendation from a pre‑planned futility analysis.
• Both the Phase 3 STAR‑121 study and the Phase 2 EDGE‑Lung study will be discontinued.
• Zimberelimab plus chemotherapy (an exploratory endpoint) performed consistently with respect to overall survival vs pembrolizumab plus chemotherapy.
• Gilead will not make the option continuation payment; its option period under the 2020 Option, License and Collaboration Agreement (as amended) ends July 14, 2026.
• As a result, Gilead will not have option rights to additional early‑stage Arcus programs (including CCR6, CD89 and CD40L) but will retain existing time‑limited options to programs including AB801, AB598, AB102 and an investigational TNF small molecule inhibitor.
• Arcus retains full rights to casdatifan and its development program, except for rights licensed to Taiho in Japan and certain other Asian territories (not including China).

Why It Matters

• For investors, the discontinuation is a material clinical setback for Arcus’s domvanalimab program and removes a Phase 3 development path in first‑line metastatic NSCLC. This may change near‑term development priorities and milestone potential tied to that program.
• The Gilead update changes the partnership scope: Arcus regains broader control of several early‑stage programs (CCR6, CD89, CD40L) because Gilead will not exercise further option rights past July 14, 2026, while some program options remain with Gilead.
• There were no new safety signals reported in regular IDMC reviews, and Gilead is coordinating patient care steps with investigators, which is important for enrolled patients’ next steps. The filing did not disclose financial impacts or changes to guidance.