French biotech stocks Abivax fell as much as 32% after it reported new data on its lead product, an ulcerative colitis drug.
The drug met its conclusions of showing clinically significant efficacy and a remission rate of nearly 40% at both doses tested, but it also showed that there was an incidence of cancer among patients taking the higher dose.
“[The] the cancer signal complicates things,” said the Jefferies analyst. “Even if the noise is unrelated, we think that the overhang will be real, especially if we consider the absence of other data events that reveal the value in the future. [year].”
In the study group, there was one reported case each of prostate cancer, breast cancer, and colonic dysplasia, which Abivax said were unrelated to the treatment.
There were also four cases of skin cancer at the higher 50 mg dose, two of which were considered unrelated or undesirable to the drug, and the other two had a medical history of skin cancer, Abivax said.
Analysts at Jefferies said the “rational explanation” of the cancer cases was sound, but “doesn’t appear to be something easily dismissed.”
The stock has gained nearly 1,700% in 2025, but shares were down 7% in trading on Tuesday. It last traded down more than 32%.
The best replacement for Abivax
The results of the study, published late Monday, were from a maintenance study in which Abivax tested the effect of the drug, olifazimod, over 44 weeks. It comes after the results of a late-stage trial of the drug for ulcerative colitis in mid-2025, which exceeded even the highest expectations.
Analysts described the experimental drug as the most effective treatment for ulcerative colitis. Abivax is also testing a drug for Crohn’s disease, opening up the multi-billion dollar market for Irritable Bowel Syndrome (IBS).
“The 44-week maintenance data demonstrate the potential of obefazimod to deliver efficacy and long-term disease control in ulcerative colitis,” said Abivax’s David Rubin, who is also director of the inflammatory bowel disease center at the University of Chicago Medicine.
“The novel approach, sustained clinical remission, and long-term safety profile highlight its potential to address a significant unmet need in UC..”
This company is positioned as a target for a takeover, which is not confirmed rumors that big pharma has its eyes on clinical-stage biotech led by CEO Marc de Garidel.
De Garidel told CNBC in March that he hopes the maintenance study will read well, and indicated that the company is not in a rush to find a deal or partnership, as terms will be better after that.
It is widely expected that Abivax will be acquired before launching obefazimod, and de Garidel told CNBC that he plans to raise funds after the June data is read.
