Merck's bowel disease drug meets main goal in late-stage trial

Merck said on Monday its experimental drug met the main goal and key secondary goals in a late-stage trial in patients with a type of inflammatory bowel disease.

At 12 weeks, the drug, tulisokibart, showed clinical remission in symptoms of ulcerative colitis.

Ulcerative colitis is a type of chronic bowel disease that causes long-lasting inflammation and ulcers in the innermost lining of the large intestine and rectum.

Merck said patients who received the drug also showed signs of improvement in the condition of their colon and reduced inflammation in tissue samples after 12 weeks.

At least two analysts said the results appeared positive, but noted the lack of quantitative details from the trial.

Citi analyst Geoff Meacham said Merck did not disclose numbers on how many patients went into remission, how different doses performed, how the drug compared with placebo, or how it worked in specific patient groups.

The lack of data, for now, "limits competitive read-through" with rival treatments, Meacham added.

Tulisokibart is designed to block TL1A, a protein involved in immune activity and scar-like tissue buildup.

RBC Capital Markets analyst Trung Huynh said the results mark the first positive late-stage data for an anti-TL1A drug, giving Merck an early lead in a drug class seen as a "compelling therapeutic option" for inflammatory bowel disease.

Huynh expects a 2027 launch and $5.2 billion in annual sales in 2034.

Merck said results from the trial will be presented with those from an ongoing maintenance study at an upcoming scientific congress.

Tulisokibart is currently being tested as a treatment for seven diseases, including ulcerative colitis, Merck said.

(Reporting by Christy Santhosh in Bengaluru; Editing by Leroy Leo)

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This story was originally published June 22, 2026 at 8:23 AM.