Abivax Phase 3 data show obefazimod hits all UC endpoints
Abivax has reported positive topline results from the Phase 3 ABTECT maintenance trial of obefazimod in adults with moderately to severely active ulcerative colitis (UC), with both the 25 mg and 50 mg once-daily doses meeting the primary endpoint and all key secondary endpoints at Week 44.
The global, randomised, double-blind, placebo-controlled study enrolled 580 participants who had responded to one of two preceding eight-week ABTECT induction trials. Participants were re-randomised to obefazimod 25 mg, 50 mg, or placebo. Clinical remission rates at Week 44 were 50.8% and 51.3% for the two active doses respectively, against a placebo rate of 10.4% — the lowest recorded in any Phase 3 UC maintenance responder re-randomisation trial to date, according to the company. Placebo-adjusted differences were 39.3 percentage points for the 25 mg dose and 40.3 percentage points for the 50 mg dose (p<0.0001 for both).
Secondary endpoints and safety
All key secondary endpoints — endoscopic improvement, endoscopic remission, histologic-endoscopic mucosal improvement (HEMI), corticosteroid-free clinical remission, and sustained clinical remission — were also met at statistically significant levels. Sustained clinical remission rates were particularly striking: 67.1% and 65.6% for the 25 mg and 50 mg groups respectively, against 15.7% for placebo.
On safety, treatment-emergent adverse events were reported in 58.0% and 71.8% of the 25 mg and 50 mg groups compared with 50.0% in the placebo arm. Rates of serious adverse events were broadly comparable across arms, and no deaths occurred in any group. A small number of non-melanoma skin cancers were observed in the 50 mg cohort; investigators noted that affected patients were, on average, substantially older than the trial population as a whole, consistent with age-related background risk. No cases of acute pancreatitis or cardiac abnormalities suggestive of cardiac fibrosis were recorded.
David T. Rubin, director of the Inflammatory Bowel Disease Centre at the University of Chicago Medicine, said the data demonstrated "obefazimod's potential to deliver meaningful efficacy and durable disease control in ulcerative colitis," adding that the novel mechanism and favourable long-term safety profile "highlight its potential to address a significant unmet need."
Regulatory and competitive context
Abivax intends to submit a New Drug Application to the FDA in the fourth quarter of 2026. The company also disclosed that open-label extension data from a Phase 2a/2b study (Study 108) showed durable clinical remission with up to seven years of exposure, a dataset that will likely feature prominently in the NDA package. Topline results from a Phase 2b induction trial of obefazimod in Crohn's disease are anticipated around mid-2027, opening a potential second indication.
The UC treatment landscape is well populated. Approved biologics and small molecules — including TNF inhibitors, integrin blockers, IL-12/23 inhibitors and JAK inhibitors — are all established options, and several companies are advancing further oral candidates. Obefazimod's positioning as a once-daily oral agent with a novel mechanism of action — enhancing expression of the micro-RNA miR-124 to modulate the inflammatory response — differentiates it mechanistically, though commercial differentiation will ultimately depend on the label Abivax secures, head-to-head positioning versus JAK inhibitors, and pricing. Regulators on both sides of the Atlantic have shown willingness to approve new UC therapies where maintenance data are robust, and the ABTECT dataset — with its unusually low placebo remission rate strengthening the signal — appears well-constructed to support that conversation. The EMA pathway has not yet been detailed in this announcement.