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Arcus Biosciences recently announced a strategic realignment of its research and development efforts following the discontinuation of a significant cancer treatment study. This decision comes after a collaborative Phase 3 trial with Gilead Sciences for advanced gastric and esophageal cancers did not meet its primary endpoint, prompting a shift in focus towards a promising kidney disease medication. The company's updated strategy emphasizes advancing its innovative HIF-2α inhibitor, casdatifan, which has demonstrated encouraging results in treating a specific form of kidney cancer.

This re-evaluation extends to other areas of the company's pipeline, including ongoing oncology programs and an expanding portfolio in immunology and inflammatory conditions. By prioritizing assets with higher potential, Arcus aims to optimize its investment in therapies that address critical unmet medical needs. The move reflects a proactive approach to pipeline management, ensuring resources are directed toward drug candidates with the most robust clinical evidence and market opportunity.

Realigning Research Priorities: From Oncology Setback to Kidney Disease Hope

Arcus Biosciences, in collaboration with Gilead Sciences, recently halted their Phase 3 STAR-221 study. This trial, which evaluated a combination therapy for untreated advanced gastric and esophageal cancers, was discontinued due to futility after an interim analysis showed no improvement in overall survival compared to standard treatments. This outcome led Arcus to re-evaluate its development pipeline, resulting in a strategic pivot to focus resources on its promising HIF-2α inhibitor, casdatifan, targeting clear cell renal cell carcinoma.

The decision to discontinue the STAR-221 study was based on recommendations from an Independent Data Monitoring Committee, which concluded that the domvanalimab-based combination therapy did not offer an advantage in overall survival. Despite the setback, the safety profile observed during the trial was consistent with existing treatments, with no new safety concerns identified. Arcus and Gilead are now working with investigators to determine the appropriate next steps for patients involved in both the STAR-221 and Phase 2 EDGE-Gastric studies, while also conducting a thorough analysis of the collected data to inform future research. This re-prioritization underscores a commitment to maximizing the impact of their drug development efforts.

Strategic Focus: Advancing Casdatifan and Expanding the Pipeline

With the discontinuation of the STAR-221 study, Arcus Biosciences is intensifying its investment in casdatifan, a HIF-2α inhibitor that holds the potential to be a leading treatment in its class. This compound has shown strong single-agent activity in over 120 patients with late-stage clear cell renal cell carcinoma (ccRCC) during the ARC-20 Phase 1/1b study. The positive results, including improvements in overall response rate and progression-free survival, compare favorably to the only currently approved HIF-2α inhibitor, highlighting casdatifan's significant therapeutic potential. Arcus maintains global development and commercialization rights for casdatifan, excluding Japan and certain Asian regions, where rights were optioned to Taiho Pharmaceutical in late 2025.

Arcus has outlined key milestones for casdatifan in the coming years. Early 2026 will see additional analyses of ARC-20 monotherapy data in late-stage ccRCC, including updated progression-free survival for the 100 mg once-daily dose. By mid-2026, more mature combination data for casdatifan with cabozantinib in patients previously treated with immunotherapy will be available, aligning with the ongoing Phase 3 PEAK-1 study. The latter half of 2026 is expected to bring initial ARC-20 data from earlier-line settings, which will inform a go/no-go decision for the Phase 3 portion of eVOLVE-RCC02, with a potential initiation of a Phase 3 registrational trial in early- or first-line ccRCC by late 2026. Beyond kidney cancer, Arcus continues to advance its broader pipeline, including quemliclustat, a CD73 inhibitor in Phase 3 for pancreatic cancer, and several small-molecule programs for immunology and inflammation, with two candidates expected to enter clinical trials in 2026 and late 2026–early 2027 for conditions like atopic dermatitis, rheumatoid arthritis, psoriasis, and ulcerative colitis.