Merck’s tulisokibart meets a Phase 3 ulcerative-colitis endpoint

The Tip Desk · September 23, 2026 · 2 min read

The sponsor’s induction readout advances the TL1A program, with detailed results and separate maintenance evidence still important.

Tulisokibart links the earlier Prometheus code PRA023 with Merck's MK-7240 program. It is an investigational antibody targeting TL1A. Merck's acquisition of Prometheus in June 2023 changed the corporate owner, not the compound's identity.

On June 22, 2026, Merck said the induction-only Study 2 within ATLAS-UC met its primary week-12 clinical-remission endpoint and key secondary endpoints. The release did not provide a complete numerical results table. It reported no new safety concerns, but that sponsor statement should not be read as proof of absence of risk or as a comparison with another drug.

The ATLAS-UC registry separates two studies: one includes induction and maintenance, while the other assesses induction only. The program uses intravenous induction and includes subcutaneous maintenance or extension arms. Study 1's week-52 remission assessment addresses a different question from Study 2's week-12 result.

Detailed results and the remaining maintenance evidence are therefore important next steps. Tulisokibart should be compared with duvakitug as another TL1A approach while retaining differences in trial design, population and follow-up. Neither a shared target nor a more advanced readout establishes superiority.

The Prometheus purchase price covered a company and wider assets; it is not money earmarked solely for this compound.

At June 30, Merck held $6.849 billion of cash and equivalents and $0.292 billion of short-term investments. Current loans and debt were $2.825 billion, alongside $51.081 billion of long-term debt. First-half operating cash generation was $9.288 billion. These figures describe the resources and obligations of the diversified group, not the economics of tulisokibart alone. Acquisition-related accounting can make earnings a poor substitute for cash flow; this context therefore reports the cash-flow measure directly.

Merck completed its acquisition of Prometheus on June 16, 2023. The change in ownership brought the program previously known as PRA023 into a larger pharmaceutical group, where it is also identified as MK-7240. The transaction covered the company and its wider assets; its value should not be presented as money assigned solely to tulisokibart. The historical owner and aliases remain useful when connecting early trials with the current Phase 3 program.