Overview of the Situation#
Arcus Biosciences Inc. (NASDAQ:RCUS) experienced a 4% drop in its stock price on Monday. This decline followed the company's announcement regarding the discontinuation of its Phase 3 STAR-121 lung cancer study, which was halted due to concerns about its effectiveness, a situation referred to as "futility."
Details of the Study#
The STAR-121 study was conducted in partnership with Gilead Sciences, Inc. It aimed to evaluate the effectiveness of a combination treatment involving domvanalimab (an anti-TIGIT antibody), zimberelimab (an anti-PD-1 antibody), and chemotherapy. This combination was compared to pembrolizumab (another anti-PD-1 antibody) plus chemotherapy for treating metastatic non-small cell lung cancer, a serious form of lung cancer.
The decision to stop the study was made based on a recommendation from the Independent Data Monitoring Committee (IDMC), which reviewed data from a planned analysis. Importantly, no new safety concerns were identified during regular reviews, although safety was not specifically assessed during the futility analysis.
Implications for Future Studies#
Alongside the STAR-121 study, Arcus also announced the discontinuation of its Phase 2 EDGE-Lung study. Gilead is currently in discussions with investigators to determine the next steps for patients who were enrolled in these trials.
Changes in Collaboration with Gilead#
In a separate announcement, Arcus revealed that Gilead's option rights under their 2020 collaboration agreement will end on July 14, 2026. This follows Gilead's decision not to make a continuation payment. As a result, Gilead will not have rights to additional early-stage programs at Arcus, although it will maintain limited options on certain existing programs. Arcus retains full rights to its casdatifan program, with some exceptions for rights licensed to Taiho in Japan and other Asian territories, excluding China.