Gilead Sciences and Arcus Biosciences ended parts of their TIGIT collaboration after a phase 3 setback. The partners discontinued the STAR-121 late-stage study of domvanalimab in metastatic NSCLC following a futility assessment, with the filing citing the inability to meet efficacy comparisons versus Merck’s Keytruda plus chemotherapy. The decision triggered rollback actions, including the discontinuation of the EDGE-Lung phase 2 study. While the companies did not flag new safety issues during data board check-ins, the futility result tightened development bandwidth for both platforms. Strategically, the termination shows how quickly TIGIT programs are being reprioritized after competitive efficacy signals fail to land against leading immunotherapy backbones.