AbiVax shares plunge as safety concerns shadow strong ulcerative colitis trial results

AbiVax reported Phase 3 data for its experimental therapy obefazimod in patients with moderately to severely active ulcerative colitis. Two dose levels achieved placebo‑adjusted clinical remission rates of about 39% and 40% after 44 weeks, far exceeding analyst expectations and being called a best‑in‑disease result.

However, investigators identified a handful of malignancies among recipients of the higher dose. The company said the cancer cases were not linked to the drug, were not clustered in any organ, and remained under investigation.

The mixed news sent AbiVax’s stock down more than 30% on the day, erasing billions of market value. The firm still intends to file for regulatory approval in the fourth quarter despite the safety signals.