Merck reported positive topline results from the Phase 3 ATLAS-UC induction-only study, with tulisokibart achieving clinical remission at week 12 in adults with moderately to severely active ulcerative colitis.
The drug also met key secondary endpoints, including endoscopic improvement, clinical response and histologic-endoscopic mucosal improvement, while showing no new safety concerns consistent with earlier Phase 2 data.
ATLAS-UC Study 2 tested high-dose and low-dose IV tulisokibart against placebo in a randomized, double-blind trial designed to show at least one dose was superior on remission by Modified Mayo Score.
Merck said the results are the first Phase 3 induction data for an anti-TL1A biologic and plans to present them alongside the ongoing induction-and-maintenance Study 1 at a scientific congress and to regulators.
Tulisokibart is being developed across 7 immune-mediated diseases, with Phase 3 programs already running in ulcerative colitis and Crohn's disease.
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Merck’s Tulisokibart Hits Key Phase 3 Milestone in Ulcerative Colitis, Paving Way for First-in-Class Anti-TL1A Therapy
Overview
On June 22, 2026, positive Phase 3 results were announced for tulisokibart (MK-7240), an investigational humanized monoclonal antibody, in treating moderately to severely active ulcerative colitis. Tulisokibart works by targeting TL1A, a protein linked to both inflammation and fibrosis in the gut. This novel approach addresses not only the inflammation seen in ulcerative colitis but also the tissue scarring that can worsen the disease. Currently, tulisokibart is being studied in two Phase 3 trials—one for ulcerative colitis and another for Crohn’s disease—highlighting its potential as a significant advancement for immune-mediated inflammatory conditions.