Abivax’s shares swung after the company’s Phase 3 ABTECT maintenance trial posted positive topline results for obefazimod in ulcerative colitis, but investors focused on malignancies seen in late-stage maintenance data. Jefferies, Morgan Stanley, Truist, and Wedbush issued divergent reactions, with some flagging a potential black-box risk. The dataset included malignancies in 9 of 580 enrolled patients, with dosing distribution spanning 25 mg, 50 mg, and placebo groups. Several analysts emphasized the need to determine whether events are drug-related, low-incidence, or a confounding background signal. The episode underscores how even positive efficacy readouts can face immediate re-rating when oncology-type safety questions emerge in inflammatory disease maintenance settings.