Abivax, a French biotechnology company, saw its shares fall as much as 32% following the release of new data from a maintenance study of its lead drug candidate, obefazimod, for ulcerative colitis [1]. The trial, which assessed the drug's effects over 44 weeks, met its primary endpoints by demonstrating clinically meaningful efficacy and a remission rate of about 40% for both tested doses [1]. However, the update also revealed that cancer cases were observed among patients receiving the higher dose of the drug [1]. According to Abivax, investigators considered these cancer cases 'unrelated to treatment,' and no organ-specific clustering was observed [1].
Despite the positive efficacy results, the emergence of cancer cases has raised concerns among analysts. A Jefferies analyst noted, 'The cancer signal complicates matters. Even if unrelated noise, we think the overhang will be real, especially considering absence of other value-inflecting data events over the next [year]' [1]. This sentiment was reflected in the market reaction, as Abivax shares, which had previously gained nearly 1,700% in 2025, dropped over 27% in recent trading after already falling 7% prior to the announcement [1].
The trial results follow a late-stage study in mid-2025 that exceeded expectations for the same drug [1]. Analysts have described obefazimod as a potential best-in-class treatment for ulcerative colitis, and the company is also testing the drug for Crohn's disease, targeting the multi-billion-dollar market for Irritable Bowel Syndrome (IBS) [1]. David Rubin, director of the inflammatory bowel disease center at the University of Chicago Medicine, stated, 'The 44-week maintenance data demonstrate obefazimod's potential to deliver meaningful efficacy and durable disease control in ulcerative colitis,' highlighting its novel mechanism and favorable long-term safety profile [1].
Abivax has been viewed as a prime takeover target, with speculation about interest from major pharmaceutical companies, though no deals have been confirmed [1]. CEO Marc de Garidel indicated that the company is not rushing into any agreements, expressing confidence that upcoming June trial data could secure better terms for future partnerships [1].
CONCLUSION
Abivax's latest trial results for its ulcerative colitis drug delivered strong efficacy but were overshadowed by the emergence of cancer cases in higher-dose patients, leading to a sharp share price decline. While the company maintains the cancer cases are unrelated to treatment, market sentiment remains cautious, and analysts expect the issue to weigh on the stock in the near term. Abivax continues to position itself for potential partnerships or acquisition, pending further trial data.