Abivax (Nasdaq: ABVX) reported Phase III ABTECT maintenance results for obefazimod in moderately to severely active ulcerative colitis that demonstrated clinically meaningful response rates in a refractory population, while expanding the long-term safety database ahead of a planned NDA submission to US FDA in Q4 2026.
In the ABTECT Maintenance Part 2 trial, patients who failed to achieve clinical response after eight weeks of induction and continued on obefazimod 50 mg reached clinical remission in 37.2% of cases and endoscopic remission in 34.5% at Week 44. Among patients who relapsed during Maintenance Part 1 and escalated from 25 mg to 50 mg, clinical remission was recaptured in 45.5%, with clinical response in 66.7%. Patients who had responded during induction, relapsed after re-randomization to placebo in Part 1, and then received open-label 50 mg obefazimod achieved clinical remission in 45.0% and clinical response in 69.7%. Across the integrated Phase II and Phase III UC program encompassing 1,704 patient-years of exposure, exposure-adjusted incidence rates for malignancies excluding non-melanoma skin cancer were 0.35 and 0.64 events per 100 patient-years in the all-active combined and 50 mg cohorts respectively, consistent with published UC background rates of 0.30–0.70 per 100 patient-years. NMSC rates of 0.59 and 0.64 per 100 patient-years similarly fell within the expected UC background range of 0.70–1.40. No new safety patterns emerged with the additional cumulative exposure from Part 2.
The ABTECT Maintenance Part 2 study enrolled patients who either did not achieve clinical response following induction or experienced disease relapse during the re-randomized Part 1 maintenance trial, representing a more refractory population than the registrational cohort. All efficacy endpoints reported from Part 2 are designated exploratory, and the data are open-label for the relapse rescue arm. The combined Phase III maintenance dataset (Part 1 plus Part 2) showed NMSC rates of 1.09 and 1.37 per 100 patient-years for the 25 mg and 50 mg cohorts respectively, sitting at the upper boundary of the published UC background reference range of 0.70–1.40; Abivax attributed the four NMSC events in Part 2 to patients with established risk factors including advanced age, prior thiopurine use, prior skin cancer history, and failure of multiple prior advanced therapies. The exploratory nature of the Part 2 efficacy data and the open-label design of the rescue arms limit direct comparison with the blinded registrational Part 1 results.