Arcus Revamps Cancer Pipeline Following Trial Miss, Prioritizes Kidney Drug

Arcus Biosciences, Inc. (NYSE:RCUS) on Friday announced the discontinuation of the Phase 3 STAR-221 study, being conducted in partnership with Gilead Sciences, Inc. (NASDAQ:GILD), due to futility. • Arcus Biosciences stock is among today’s weakest performers. Why is RCUS stock dropping? The decision is based on the recommendation from the Independent Data Monitoring Committee (IDMC) following its review of data from an event-driven, pre-specified interim analysis of overall survival (OS). STAR-221 evaluated the anti-TIGIT antibody domvanalimab plus anti-PD-1 antibody zimberelimab and chemotherapy versus nivolumab plus chemotherapy for untreated patients with advanced gastric and esophageal cancers. At the interim analysis, the domvanalimab-based combination did not improve OS relative to that of nivolumab plus chemotherapy. The safety profile for the domvanalimab-based combination was similar to that of nivolumab plus chemotherapy, and there were no new safety findings identified. Also Read: Gilead Sciences/Arcus Biosciences’ Investigational Cancer Drug Shows Overall Survival Of Around 27 Months The STAR-221 and the Phase 2 EDGE-Gastric studies will be discontinued, and Arcus and Gilead are communicating with investigators to determine appropriate next steps for patients in the study, in addition to conducting a detailed analysis. Casdatifan and Clear Cell Renal Cell Carcinoma (ccRCC) Patients Arcus will concentrate its R&D investment on casdatifan, a potential best-in-class HIF-2α inhibitor. Casdatifan targets a well-validated pathway and has demonstrated strong single-agent activity in more than 120 late-line clear cell renal cell carcinoma (ccRCC) patients enrolled in the ARC-20 Phase 1/1b study. The data show improvement across all efficacy measures, including overall response rate and progression-free survival, versus results reported for the only approved HIF-2α inhibitor. Arcus retains global rights to casdatifan outside Japan and parts of Asia, which were optioned to Taiho Pharmaceutical in October 2025. The 2025 milestones for casdatifan are: Early 2026: Additional ARC-20 monotherapy analyses in late-line ccRCC, including updated PFS for the 100 mg QD dose selected for Phase 3. Mid-2026: More mature ARC-20 combination data for casdatifan + cabozantinib in IO-experienced patients, aligned with the ongoing Phase 3 PEAK-1 study. Second Half 2026: Initial ARC-20 data in earlier-line settings and a go/no-go decision for the Phase 3 portion of eVOLVE-RCC02. Late 2026: Potential initiation of a Phase 3 registrational trial in early- or first-line ccRCC. Oncology Pipeline Arcus is also advancing quemliclustat, a small-molecule CD73 inhibitor. The Phase 3 PRISM-1 trial in first-line metastatic pancreatic ductal adenocarcinoma completed enrollment earlier this year. Results are expected in 2027, evaluating quemliclustat plus gemcitabine/nab-paclitaxel versus the standard regimen. I&I Pipeline Arcus's immunology and inflammation portfolio includes several oral small-molecule programs targeting markets dominated by injectables. Two candidates are expected to enter the clinic within the following timelines: 2026: MRGPRX2 for atopic dermatitis and chronic spontaneous urticaria. Late 2026–Early 2027: TNF inhibitor for rheumatoid arthritis, psoriasis and inflammatory bowel disease, including ulcerative colitis. RCUS Price Action: RCUS stock is down 11.10% at $23.35 at publication on Friday. Read Next: Reddit Files Lawsuit Against Australia’s Under-16 Social Media Ban Citing Free Speech Violation Photo: Shutterstock