Shares of French biotech Abivax tumbled as much 32% after it reported fresh data on its lead asset, a drug for ulcerative colitis.
The medicine met its endpoints of demonstrating a clinically meaningful efficacy and a remission rate of about 40% for both doses tested, but also showed that there were cancer cases among patients taking the higher dose.
Abivax said the cancer cases were considered “unrelated to treatment by investigators, and no organ-specific clustering was observed.”
“[The] cancer signal complicates matters,” a Jefferies analyst said. “Even if unrelated noise, we think the overhang will be real, especially considering absence of other value-inflecting data events over the next [year].”
The stock gained nearly 1,700% in 2025, but shares had fallen 7% coming into Tuesday trading. It was last trading down over 27%.
Abivax shares year-to-date.
The trial results, published late Monday, were from a maintenance study in which Abivax assessed the effect of the drug, obefazimod, over 44 weeks. It comes after the results of a late-stage trial for an ulcerative colitis medicine in mid-2025, beating even the most optimistic expectations.
With analysts describing the experimental drug as a potential best-in-class treatment for ulcerative colitis. Abivax is also testing the medicine for Crohn’s disease, opening it up to a multi-billion-dollar market for Irritable Bowel Syndrome (IBS).
“The 44-week maintenance data demonstrate obefazimod’s potential to deliver meaningful efficacy and durable disease control in ulcerative colitis,” said Abivax’s David Rubin, also director of the inflammatory bowel disease center at the University of Chicago Medicine.
“The novel mechanism, sustained clinical remission, and favorable long-term safety profile highlight its potential to address a significant unmet need in UC.”
The company has been positioned as a prime takeover target, with unconfirmed speculation that big pharma has its eyes on the clinical-stage biotech led by CEO Marc de Garidel.
This is breaking news. Please refresh for updates.
