Merck said its anti-TL1A antibody tulisokibart (developed from the Prometheus Biosciences acquisition) achieved a positive Phase 3 result in ulcerative colitis. In the ATLAS-UC induction-only study of patients with moderately to severely active disease, Merck reported benefit versus placebo on clinical remission at week 12 using the Modified Mayo Score, and it said no safety concerns emerged. Merck indicated it will share detailed results with regulators and at an upcoming scientific meeting, alongside data from an ongoing induction and maintenance study. The company framed the result as the first clinical-remission positive outcome at 12 weeks for the anti-TL1A approach in this patient population. The update adds momentum to Merck’s immunology strategy in a crowded UC market where IL-23 inhibitors, JAK inhibitors, and integrin-based therapies compete for switching and line-of-therapy decisions. Merck is also running additional trials across Crohn’s disease and other immune-mediated indications. Industry focus will now center on whether the drug demonstrates differentiation beyond induction—especially around durability, endoscopic improvement, and biomarker-defined responses as more data mature.