Shares in Abivax plunge as safety concerns cloud trial results

(Sharecast News) - Shares in Abivax tanked on Tuesday, after trial results for an inflammatory bowel drug developed by the French biotech disappointed.

Obefazimod is an investigational oral treatment for adults with moderately to severe active ulcerative colitis (UC).

Publishing phase III results, Abivax said that at week 44, both the 25mg and 50mg doses had met their primary endpoint of clinic remissions and all key secondary endpoints. Chief executive Marc de Garidel called the outcome a "landmark", adding: "With its compelling durable efficacy and favourable safety profile, combined with the convenience of a once-daily oral treatment, obefazimod has the potential to transform UC patient care."

However, investors focused instead on three patients in the study for the 50mg dose who each had one case each of prostate cancer, breast cancer and colonic dysplasia. Abivax said it considered the cases unrelated to treatment, but that did not stop the shares plunging, and by 1000 BST the Paris-listed stock had shed 29%.

There were also four cases of skin cancer on the higher dose. Abivax said two were deemed unlikely to be related to the drug, while the other two had a medical history of skin cancer.

Jefferies said the cancer cases "broke" its investment theses. In a note to investors, analysts said: "Even if proven to be not drug-related or very low incidence, we expect an overhang to investor interest, strategic optionality and commercial uptake."

According to Reuters, analysts at Truist Securities acknowledged that the drug's efficacy was impressive, but said safety questions were likely to affect the shares, even if causality had not been confirmed.