Abivax SA ADR (NASDAQ:ABVX) saw its stock climb 18.5% in after-hours trading Monday after the company reported positive findings from the ABTECT Maintenance Part 2 Phase 3 trial evaluating obefazimod in patients with ulcerative colitis.
The trial reported that 37.2% of patients who had not responded to initial induction therapy reached clinical remission by Week 44 while continuing on 50 mg of obefazimod. In the same cohort, 34.5% achieved endoscopic remission. The study population included patients who either failed to respond to induction or experienced disease relapse during the first part of the maintenance program.
For patients who relapsed during Maintenance Part 1, escalating the dose to 50 mg recaptured clinical remission in 45.5% of those who had relapsed while on the 25 mg dose. Additionally, patients who relapsed after being switched to placebo and were then re-treated with 50 mg obefazimod achieved clinical remission at a rate of 45.0%.
The trial data also broadened the safety database for obefazimod. Across the integrated Phase 2 and Phase 3 programs, the combined exposure amounted to 1,704 patient-years. Within the active treatment groups, the exposure-adjusted incidence rate for malignancies excluding non-melanoma skin cancer was 0.35 events per 100 patient-years, which falls within the cited expected ulcerative colitis background range of 0.30-0.70 events per 100 patient-years.
For non-melanoma skin cancer specifically, the exposure-adjusted incidence rate in the combined active groups was 0.59 events per 100 patient-years, a figure that is within the referenced expected background range for ulcerative colitis of 0.70-1.40 events per 100 patient-years.
Abivax indicated it remains on schedule to submit a New Drug Application for obefazimod to the U.S. Food and Drug Administration in the fourth quarter of 2026. The company is also running a Phase 2b trial of obefazimod in Crohn's disease, with topline results anticipated in mid-2027.
Context and market reaction
The reported efficacy and safety figures were followed by a notable uptick in trading post-market, reflecting investor response to the Phase 3 maintenance data. The results include both primary remission endpoints and data on rescue strategies for patients who relapsed on lower doses or placebo.
What the data show
- Continued 50 mg obefazimod produced clinical remission in 37.2% of non-responders to induction by Week 44 and endoscopic remission in 34.5%.
- Dose escalation to 50 mg recaptured remission in 45.5% of patients who relapsed on 25 mg; re-treatment after placebo relapse led to 45.0% remission.
- Safety exposure across Phase 2 and Phase 3 programs summed to 1,704 patient-years, with malignancy and non-melanoma skin cancer rates within expected background ranges for ulcerative colitis.