Merck’s Phase 3 ATLAS-UC trial met its primary endpoint, with tulisokibart becoming the first anti-TL1A therapy to achieve clinical remission in moderate-to-severe ulcerative colitis at 12 weeks.
Written By: Farha Farheen, PharmD
Reviewed By: Pharmacally Editorial Team
Merck has reported positive topline results from the Phase 3 ATLAS-UC Study 2 (NCT06052059) evaluating tulisokibart (MK-7240) in adults with moderately to severely active ulcerative colitis (UC). The investigational anti-TL1A monoclonal antibody met the study’s primary endpoint, demonstrating clinical remission at Week 12 based on the Modified Mayo Score (MMS), while also achieving key secondary endpoints.
The findings mark the first Phase 3 demonstration of clinical remission by an anti-TL1A therapy in ulcerative colitis, strengthening interest in this emerging therapeutic class for inflammatory bowel disease (IBD). Merck reported no new safety concerns, with results remaining consistent with previous Phase 2 studies.
Targeting Inflammation and Fibrosis in Ulcerative Colitis
Tulisokibart is a humanized monoclonal antibody that targets tumor necrosis factor-like cytokine 1A (TL1A), a signaling protein implicated in both intestinal inflammation and fibrosis. Unlike many current therapies that primarily suppress inflammation, TL1A inhibition may address immuno-fibrosis, a process that contributes to chronic tissue damage and disease progression in ulcerative colitis and other immune-mediated disorders.
Ulcerative colitis is a chronic inflammatory bowel disease affecting the colon and rectum. Patients often experience recurrent episodes of diarrhea, rectal bleeding, abdominal pain, bowel urgency, and weight loss. Despite multiple approved treatment options, many patients fail to achieve sustained remission or adequate disease control.
Phase 3 ATLAS-UC Study Met Primary and Key Secondary Endpoints
ATLAS-UC (NCT06052059) is a randomized, double-blind, placebo-controlled Phase 3 program consisting of two independent studies. The newly reported Study 2 evaluated induction therapy only and enrolled adults with moderately to severely active ulcerative colitis.
Participants were randomized to receive either a high-dose intravenous regimen of tulisokibart, a low-dose intravenous regimen, or placebo.
The study met its primary endpoint, demonstrating superiority over placebo in the proportion of patients achieving clinical remission according to the Modified Mayo Score at Week 12.
Key secondary endpoints were also achieved, including:
- Endoscopic improvement at Week 12
- Clinical response based on Modified Mayo Score criteria
- Histologic-endoscopic mucosal improvement
Merck has not yet disclosed detailed efficacy percentages or statistical analyses. Full data will be presented at an upcoming scientific congress alongside results from ATLAS-UC Study 1, which is evaluating both induction and maintenance treatment.
Expanding the Anti-TL1A Development Landscape
According to Dr. Eliav Barr, Senior Vice President, Head of Global Clinical Development and Chief Medical Officer at Merck Research Laboratories, the findings represent an important milestone for patients who continue to experience symptoms despite existing treatment options. He noted that the results support the potential of targeting immuno-fibrosis as a novel approach to modifying disease progression in ulcerative colitis.
Clinical Path Forward
Merck plans to present comprehensive Phase 3 data at a forthcoming medical meeting and share the results with regulatory authorities.
Tulisokibart currently has one of the broadest development programs among anti-TL1A therapies. In addition to Phase 3 studies in ulcerative colitis and Crohn’s disease, the antibody is being evaluated in Phase 2 trials across several immune-mediated conditions, including rheumatoid arthritis, psoriatic arthritis, radiographic axial spondyloarthritis, hidradenitis suppurativa, and systemic sclerosis-associated interstitial lung disease.
The Phase 3 success in ulcerative colitis positions tulisokibart as a leading candidate in the emerging anti-TL1A class and may further validate fibrosis-focused approaches in chronic inflammatory diseases.
What This Means for Patients
These results offer hope for people living with moderate to severe ulcerative colitis, especially those who continue to experience symptoms despite currently available treatments. If tulisokibart is approved, it could provide a new treatment option that may help patients achieve longer-lasting symptom relief, fewer disease flare-ups, and better day-to-day quality of life. Because the therapy targets both inflammation and tissue scarring, it may also help slow disease progression and reduce the likelihood of complications that can lead to hospitalization or surgery. More research is still needed, but these findings represent an important step toward expanding treatment choices for people with ulcerative colitis.
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About the Writer
Farha Farheen, PharmD (LinkedIn) is a pharmacy professional with a strong interest in pharmacovigilance and clinical research. She has completed her Doctor of Pharmacy (Pharm.D) along with her internship as a Clinical Pharmacist. She has hands-on experience in adverse drug reaction (ADR) reporting, safety data documentation, and pharmacovigilance workflows, and is proficient in using VigiFlow. She is also a patent holder for an antibacterial formulation enriched with bioactive substances, granted by the German Patent and Trademark Office.