Arcus supports TIGIT combo with positive data from canceled trial

Arcus Biosciences has provided data from a discontinued late-stage study of its drug combination targeting TIGIT and PD-1, supporting its plan to pursue this treatment approach for a different type of lung cancer. The Phase 3 ARC-10 trial, which was conducted with the assistance of Gilead, focused on evaluating Arcus’ anti-TIGIT antibody domvanalimab in combination with the PD-1 drug zimberelimab. The study targeted patients with first-line locally advanced or metastatic non-small cell lung cancer (NSCLC) who had a PD-L1 tumor proportion score of at least 50%.

Despite the initial setup, the companies decided to halt the ARC-10 study in January. They have now initiated the Phase 3 STAR-131 trial, which will test the same drug combination in a different context, specifically perioperative lung cancer.

In the ARC-10 study, which included 98 participants, the combination of domvanalimab and zimberelimab was found to reduce the risk of death by 36% compared to zimberelimab alone, based on a median follow-up period of 24.5 months. For the primary endpoint of the trial, zimberelimab alone reached a median overall survival of two years, while the combination treatment has not yet reached the median overall survival.

Arcus highlights that the data from the ARC-10 study underscore the potential effectiveness of combining TIGIT inhibitors with PD-1 inhibitors. In January, Gilead invested $320 million in its partnership with Arcus, which Mizuho analysts suggested could be a step towards Gilead increasing its equity stake in Arcus, potentially hinting at future acquisition plans.

The results from the ARC-10 study are scheduled to be presented at the Society for Immunotherapy of Cancer annual meeting in Houston. Additionally, another set of trials is currently underway, featuring a trio of treatments—domvanalimab, zimberelimab, and chemotherapy. These trials are evaluating the combination in patients with untreated metastatic non-small cell lung cancer and gastrointestinal cancer.