Abivax Reports Positive Phase 3 Results for Ulcerative Colitis Drug Obefazimod

French biotech company Abivax has announced promising top-line data from two phase 3 trials of its lead ulcerative colitis candidate, obefazimod. The oral small molecule demonstrated statistically significant remission rates in patients with moderate to severe ulcerative colitis, potentially offering a novel treatment option in a competitive therapeutic landscape.

Trial Results and Clinical Significance

The twin phase 3 trials, ABTECT-1 and ABTECT-2, enrolled a combined 1,275 patients globally to evaluate two daily doses of obefazimod (50 mg and 25 mg) against placebo. The primary endpoint was the remission rate after eight weeks of treatment, measured using a modified version of the Mayo Score.

Across both trials, obefazimod achieved a pooled remission rate of 16.4%, meeting the studies' primary endpoints. In ABTECT-1, both dosage groups showed significantly higher remission rates compared to placebo. However, in ABTECT-2, only the 50-mg group demonstrated a significant difference.

Dr. Fabio Cataldi, Abivax's Chief Medical Officer, attributed the discrepancy in ABTECT-2 results to the specific patient population randomized to the 25-mg group, stating, "The patient population randomized to the 25-milligram dose in ABTECT-2 was the most difficult to treat population across both ABTECT-1 and ABTECT-2. Based on baseline disease characteristics, we believe this type of patient might require more than eight weeks to achieve clinical remission."

Safety Profile and Mechanism of Action

Obefazimod's safety profile in the phase 3 trials was consistent with previous studies, with no new safety concerns identified. Some patients experienced headaches, particularly in the early stages of treatment, but these were reported to be transient and less prevalent than in earlier phase studies.

Dr. David Rubin, a gastroenterologist and director of the Inflammatory Bowel Disease Center at the University of Chicago Medicine, explained the drug's unique mechanism of action: "We have no other therapies in our field that treat the disease the way this mechanism is believed to work. The way I like to explain it is that rather than targeting specific active inflammation, it shuts it off at the source, resetting a balance of the immune system."

Obefazimod is designed to boost levels of microRNA-124 in the intestines, helping to control inflammation. This novel approach could position the drug as a first-in-class option for ulcerative colitis patients, should it receive regulatory approval.

Regulatory Timeline and Financial Outlook

Abivax plans to submit obefazimod for approval to both the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) in the second half of 2026. This timeline aligns with the expected completion of an ongoing maintenance trial, which will follow patients from both ABTECT-1 and ABTECT-2 until 2030.

However, the company faces financial challenges as it approaches these milestones. Chief Financial Officer Didier Blondel revealed that Abivax's cash runway is set to run out by the fourth quarter of 2025. "We know we need to raise money in the short term," Blondel stated. "What we want to do at minimum is to be able to fund the company until the maintenance data readout," which is scheduled for the second quarter of 2026.

Abivax's journey with obefazimod has been marked by financial struggles, with the company pivoting the drug's development from HIV to ulcerative colitis after disappointing midstage HIV trial results. The company has relied on various funding sources, including investments from Sofinnova, a European stock sale in 2022, and an initial public offering in 2023, to sustain its operations.

As Abivax works to secure additional funding and advance obefazimod through the regulatory process, the drug's potential entry into the ulcerative colitis market could disrupt a space currently dominated by immunotherapies from major pharmaceutical companies such as AbbVie, Johnson & Johnson, Takeda, Pfizer, and Bristol Myers Squibb.