Abivax Races to Defend Safety Profile After Promising Ulcerative Colitis Data Sparks Divergent Analyst Views

Abivax shares tumbled on obefazimod Phase 3 results: strong remission rates but eight malignancies spook investors, splitting analysts and sparking a securities investigation.

The market’s verdict on Abivax’s pivotal ABTECT study was swift and severe. Shares in the French biotech cratered by more than 40% on 2 June after the Phase 3 maintenance data delivered a double-edged message: best-in-class efficacy for obefazimod in ulcerative colitis, but a worrying cluster of malignancies that has sent investors scrambling to reassess risk. By Friday, the stock had clawed back some ground to trade at 91.55 euros, a 2.92% gain on the session, but the weekly loss still stood at 19.27% and the year-to-date decline at 20.53%.

The emotional whipsaw stems from a sharp disconnect between the drug’s performance and its safety baggage. In the 25 mg arm, 50.8% of patients achieved clinical remission at week 44, versus 51.3% in the 50 mg arm. Placebo managed only 10.4%. With a p-value below 0.0001, the statistical strength is not in doubt. Yet the higher dose produced seven malignancies – one prostate cancer, one breast cancer, a colorectal dysplasia, and four cases of non-melanoma skin cancer. An additional malignancy appeared in the 25 mg group, bringing the total to eight.

Abivax stresses that all events were classified as not treatment-related. The company also notes that the skin cancer patients had an average age of 62, compared with 42 for the study population as a whole, and that no organ-specific cluster was observed. But the market has so far refused to give management the benefit of the doubt. The stock’s 30-day annualised volatility has spiked to 156.43%, and the relative strength index of 45.5 suggests the selling wave has moderated but not fully exhausted.

Analysts are now deeply split on how to weigh the trade-off. Jefferies slashed its rating to “Hold” with a price target of $90, while Wolfe Research, Citizens and Morgan Stanley remain far more optimistic, pegging targets at $136, $187 and $132 respectively. The disparity reflects the core uncertainty: those focused on the remission data see a drug with clear regulatory and commercial potential; those zeroing in on the safety signal anticipate either a prolonged FDA review or a restrictive label that would limit peak sales.

The legal picture has also darkened. Levi & Korsinsky, a shareholder rights firm, is investigating potential securities law violations related to the disclosure of the study results and the subsequent sell-off. That adds another layer of headline risk to an already volatile story.

Financially, Abivax has breathing room. Cash and equivalents stood at 491.6 million euros as of 31 March, enough, the company says, to fund operations through the fourth quarter of 2027. That runway covers the planned New Drug Application submission to the FDA in the fourth quarter of 2026, as well as the expected induction data for obefazimod in Crohn’s disease, due in mid-2027. A detailed safety update is promised for this month.

In the nearer term, the stock’s technical picture offers little comfort. The share price has fallen below its 100.20-euro moving average, and the 12-month gain – still a staggering 1,209.73% – does little to cushion the short-term pain. The debate now hinges on whether Abivax can construct a convincing safety narrative that allows the efficacy advantage to drive the valuation. If the FDA requests an advisory committee or insists on a black-box warning, the risk premium will stay elevated. Until that clarity arrives, the stock is likely to remain hostage to every new piece of safety data and analyst note.