Abivax Reports Positive Phase 3 Maintenance Data for Obefazimod in Ulcerative Colitis

Abivax SA ADR (NASDAQ: ABVX), a clinical-stage biotechnology company, released positive results from the ABTECT Maintenance Part 2 trial evaluating obefazimod in ulcerative colitis patients on June 29, 2026. Investors sent shares up 18.5% in after-hours trading. The data extend Abivax’s growing efficacy and safety record for obefazimod as the company moves toward an FDA submission later this year.

Obefazimod Resets the Inflammatory Cascade at Its Source

Most approved ulcerative colitis therapies neutralize circulating inflammatory proteins after the immune system has already activated them. Obefazimod instead intervenes earlier in the process by enhancing the expression of microRNA-124 (miR-124), a natural regulator of inflammation. Once elevated, miR-124 downregulates a wide range of pro-inflammatory cytokines and chemokines, including IL-6, IL-17, TNF-alpha, and CCL2/MCP-1. Physicians have described this approach as a physiological brake on inflammation rather than a targeted strike against a single pathway. Because obefazimod modulates the immune response broadly rather than blocking one specific protein, it offers UC patients a mechanism distinct from existing biologics and small molecules.

Phase 3 Data Show Strong Recapture and Remission Rates

Abivax designed the ABTECT Maintenance Part 2 trial to evaluate patients who either failed to respond to induction treatment or relapsed during the first part of the maintenance study. Among non-responders, 37.2% achieved clinical remission at Week 44 after continued treatment with 50 mg obefazimod, and 34.5% reached endoscopic remission. The trial also tested dose escalation as a rescue strategy: when patients who relapsed on the 25 mg dose moved up to 50 mg, the higher dose recaptured clinical remission in 45.5% of cases. Patients who relapsed after switching to placebo fared similarly well, achieving a 45.0% clinical remission rate once re-treated with 50 mg obefazimod. Together, these results demonstrate that obefazimod can rescue a meaningful share of patients who initially lose response or fail to respond at all.

An Expanding Safety Database Reinforces the Drug’s Tolerability

Abivax has now accumulated 1,704 patient-years of exposure data across its integrated Phase 2 and Phase 3 programs, giving the company one of the deepest safety datasets in the UC space. Across that exposure, the combined active treatment groups recorded an exposure-adjusted incidence rate of 0.35 malignancy events per 100 patient-years (excluding non-melanoma skin cancer), a figure that falls squarely within the expected UC background rate of 0.30 to 0.70 events per 100 patient-years. Non-melanoma skin cancer occurred at a rate of 0.59 events per 100 patient-years, which sits comfortably below the expected background range of 0.70 to 1.40 events. These figures matter enormously for a chronic, lifelong therapy, since regulators and physicians alike scrutinize long-term cancer risk closely when evaluating immune-modulating drugs.

Obefazimod’s Mechanism Builds on a Validated Scientific Foundation

Abivax did not arrive at obefazimod’s mechanism by accident. Researchers first published evidence in 2023 showing that the molecule enhances selective splicing of a long non-coding RNA to generate miR-124, and the company has since reinforced that finding through peer-reviewed publications in journals including Clinical and Translational Gastroenterology and the Journal of Crohn’s and Colitis. Earlier open-label maintenance data also showed that 53% of patients achieved clinical remission after two years of continuous treatment with the 50 mg dose. This combination of mechanistic clarity and durable, multi-year efficacy data has helped Abivax build a credible case that obefazimod could become a long-term maintenance option rather than a short-term fix.

Abivax Targets a Fourth-Quarter FDA Submission and a Broader IBD Pipeline

Abivax remains on track to submit a New Drug Application for obefazimod in ulcerative colitis to the FDA during the fourth quarter of 2026. The company is simultaneously running a Phase 2b trial evaluating obefazimod in Crohn’s disease, with topline results expected in mid-2027. If that trial succeeds, Abivax would extend obefazimod’s reach across the two largest indications within inflammatory bowel disease, a combined market that includes millions of patients globally. CEO Marc de Garidel has emphasized that obefazimod’s combination of durable efficacy, a favorable safety profile, and once-daily oral convenience could meaningfully reshape how physicians approach UC treatment.

Strategic Investment Summary

• Trial Catalyst: Abivax (NASDAQ: ABVX) announced positive ABTECT Maintenance Part 2 results on June 29, 2026, sending shares up 18.5% in after-hours trading.
• Recapture Efficacy: Among initial non-responders, 37.2% achieved clinical remission and 34.5% reached endoscopic remission at Week 44 with continued 50 mg dosing.
• Dose Escalation Rescue: Escalating relapsed patients from 25 mg to 50 mg recaptured clinical remission in 45.5% of cases, demonstrating a viable rescue pathway within the dosing regimen.
• Differentiated Mechanism: Obefazimod enhances miR-124 expression to downregulate multiple inflammatory cytokines simultaneously, distinguishing it from single-target biologics already on the market.
• Safety Reassurance: Across 1,704 patient-years of exposure, malignancy and non-melanoma skin cancer rates both fell within or below expected UC background incidence ranges.
• Regulatory Timeline: Abivax plans to submit its NDA for obefazimod in ulcerative colitis to the FDA in the fourth quarter of 2026.
• Pipeline Expansion: A Phase 2b trial in Crohn’s disease is underway, with topline data expected in mid-2027, positioning obefazimod for a potential second major IBD indication.

Find out more about the latest clinical updates and financial reports at the Abivax investor portal.