Merck announced on June 23 that its investigational antibody tulisokibart achieved clinical remission in a late-stage study for patients with ulcerative colitis. The company said the intravenous TL1A inhibitor met its primary endpoint at 12 weeks and also reached key secondary outcomes, though it did not specify which ones or provide detailed data. Merck stated it will share more comprehensive findings at an upcoming medical congress.
Analysts expressed caution about the asset’s prospects due to the lack of specific information and potential competition. BMO Capital Markets told investors in a note that "lack of detail meters upside," acknowledging Merck’s commentary appeared encouraging but emphasizing the need for full quantitative data before assessing the opportunity for treating ulcerative colitis. BMO highlighted Roche’s afimkibart as a possible competitor, noting that Roche acquired this anti-TL1A antibody—which can be administered intravenously or subcutaneously—through its $7.1 billion acquisition of Telavant in October 2023.
In the Phase 2b TUSCANY-2 study, Roche’s afimkibart saw 35% of patients achieve clinical remission at 14 weeks compared to 12% on placebo, setting a benchmark for Merck's therapy to surpass if it is to be competitive. Analysts said, “With Merck’s tulisokibart administered by IV and Roche’s afimkibart administered subcutaneously in the induction setting, tulisokibart’s efficacy would likely need to be meaningfully improved vs. afimkibart to be competitive and support strong preferential uptake if approved.”
To address these challenges, Merck is developing a subcutaneous formulation of tulisokibart intended for maintenance treatment. BMO noted this could help mitigate headwinds related to market uptake.
Guggenheim Partners offered a more optimistic perspective on Merck's results, stating that the readout "supports our above-consensus estimates for the product." The firm projects peak sales exceeding $5 billion by the late 2030s, while consensus estimates are around $4 billion. Guggenheim analysts added, “While some investors might be disappointed that no quantitative efficacy data were shared at this time, we would note that this is consistent with how MRK has historically toplined its data.”
Beyond ulcerative colitis, Merck reported it is conducting additional trials with tulisokibart in conditions including Crohn’s disease, systemic sclerosis-associated interstitial lung disease, and rheumatic arthritis.
