Abivax's Ulcerative Colitis Drug Shows Promise in Phase 3 Trials, Stock Soars

French biotech company Abivax has reported positive Phase 3 results for its experimental ulcerative colitis medicine, obefazimod, sending its stock price skyrocketing. The drug, which represents a novel approach in treating inflammatory bowel disease (IBD), has positioned itself as a frontrunner in the rapidly growing market for oral IBD treatments.

Trial Results and Clinical Significance

Abivax conducted two studies, ABTECT-1 and ABTECT-2, involving patients with moderately to severely active ulcerative colitis who had not responded adequately to previous therapies. The 50 milligram dose of obefazimod achieved a pooled 16.4% placebo-adjusted clinical remission rate at week 8, surpassing the results observed in Phase 2 testing.

The drug met its primary endpoints and all key secondary endpoints at the 50 milligram dose. While the 25 milligram dose did not reach statistical significance for clinical remission in the ABTECT-2 study, its pooled clinical response rate suggested that remission might be achievable with extended treatment.

Market Impact and Financial Implications

Following the announcement of these results, Abivax's shares experienced a dramatic surge of over 500% on the Paris exchange, closing at approximately 56 euros on Wednesday, up from 8.90 euros the previous day.

Leerink Partners analyst Thomas J. Smith has revised his peak sales forecast for obefazimod to about $4 billion for both ulcerative colitis and Crohn's disease, up from an earlier estimate of $2.6 billion. Smith noted that the drug offers a "compelling balance of efficacy, safety and convenience."

The IBD market, which includes both ulcerative colitis and Crohn's disease, is projected to reach $30 billion by 2030, according to estimates from Leerink Partners. This growth potential has attracted significant attention from major pharmaceutical companies, with Merck & Co., Roche, Pfizer, and Eli Lilly all making substantial investments in recent years to acquire companies developing experimental drugs for inflammatory conditions.

Next Steps and Regulatory Timeline

Researchers are currently conducting a 44-week maintenance trial, with topline results expected in the second quarter of 2026. If these results prove positive, Abivax plans to submit applications to U.S. and European regulators in the second half of 2026.

The ABTECT study program, which includes the ongoing maintenance trial, involves more than 600 sites worldwide and 1,275 patients, making it one of the largest studies ever undertaken in ulcerative colitis. This extensive clinical program underscores the potential significance of obefazimod in the treatment landscape for IBD.