Abivax’s ulcerative colitis pill shows high remission rates but cancer cases spark safety worries

Abivax reported that its experimental oral therapy for ulcerative colitis achieved strong efficacy in a Phase 3 maintenance trial involving 580 patients who had previously responded in shorter studies. Participants took either a 25‑mg or 50‑mg daily dose of the drug, obefazimod, and were followed for 44 weeks.

Remission was observed in 50.8% of patients on the 25‑mg dose and 51.3% on the 50‑mg dose, compared with just 10.4% of those receiving placebo, representing the highest placebo‑adjusted remission rates seen in a long‑term ulcerative colitis trial.

However, the company disclosed a small number of cancer cases among treated patients, prompting safety concerns. The news sent Abivax’s shares sharply lower in post‑market trading as investors weighed the efficacy gains against the potential risk.

The mixed outcome underscores the need for further safety monitoring and may influence the timing of regulatory discussions, while the robust remission data keep the drug on the radar of clinicians and investors alike.