Abivax shares rise 35% after safety data eases cancer risk

Shares of French biotechnology company Abivax surged on Tuesday, June 30, 2026, recovering most of a steep decline from earlier in the month after new clinical trial data eased investor concerns about potential cancer risks associated with its experimental ulcerative colitis drug. The company's stock, listed in Paris and the United States, rose approximately 35% to 36% on the day, clawing back a significant portion of the 44% drop it suffered on June 2.

That earlier selloff was triggered by data showing seven distinct cancer diagnoses among patients taking the highest dose of Abivax's lead drug candidate, obefazimod, in a Phase 3 trial. While investigators had assessed those cases as unlikely related to the drug, the disclosure rattled the market. The newly released data, covering the second part of the Phase 3 ABTECT maintenance trial, provided a larger and more reassuring safety picture.

The expanded analysis combined safety data from Phase 2 and Phase 3 programs, representing the equivalent of 1,704 patient-years of drug exposure. Within this larger dataset, the rate of malignancies, excluding non-melanoma skin cancer, across all active treatment doses was 0.35 events per 100...