Abivax answers safety questions with new data
Abivax has reported additional Phase III maintenance data for obefazimod in ulcerative colitis, giving the French biotech more efficacy and safety evidence to support its planned US regulatory filing later this year.
Why it matters: The new readout follows a market sell-off earlier this month, when strong Phase III maintenance efficacy data were overshadowed by investor concerns over malignancy cases seen in the 50 mg arm.
Zoom in: The latest results come from ABTECT Maintenance Part 2, a supplemental portion of the Phase III programme that enrolled patients who either did not respond after induction treatment or relapsed during the earlier maintenance trial.
- In induction non-responders, continued treatment with 50 mg obefazimod led to clinical remission in 37.2% of patients and endoscopic remission in 34.5% at Week 44.
- In patients who relapsed during maintenance, treatment with open-label 50 mg obefazimod recaptured clinical remission in 45.0% of patients previously re-randomised to placebo and 45.5% of those escalated from 25 mg to 50 mg.
The context: These patients represent a more difficult-to-treat population than the registrational maintenance cohort. The data therefore support the company’s argument that some patients may benefit from longer exposure or dose escalation, although the Part 2 analyses are less definitive than the earlier placebo-controlled maintenance results.
What we’re watching: Abivax also used the update to expand its safety analysis.
- Across the integrated Phase II and Phase III ulcerative colitis programme, covering 1,704 patient-years of exposure, the company said exposure-adjusted incidence rates for malignancies excluding non-melanoma skin cancer were 0.35 events per 100 patient-years across all active treatment and 0.64 in the 50 mg cohort. For non-melanoma skin cancer, rates were 0.59 and 0.64 events per 100 patient-years, respectively.
- Those figures fall within the ulcerative colitis background ranges cited by Abivax. But the narrower Phase III maintenance dataset remains more mixed: in the 50 mg group, the exposure-adjusted rate for malignancies excluding non-melanoma skin cancer was 0.91 events per 100 patient-years, above the company’s cited background range of 0.30 to 0.70. The rate for non-melanoma skin cancer was 1.37 events per 100 patient-years, near the upper end of the cited 0.70 to 1.40 range.
What they’re saying: Abivax said the additional data strengthen confidence in obefazimod’s benefit-risk profile ahead of a planned New Drug Application submission to the FDA in the fourth quarter of 2026.
Market reaction: Investors appeared to respond positively after the data were released. Abivax’s Euronext stock jumped from €83,3 at closing yesterday to €103,5 this morning at opening (+24%) and was still climbing at the time we published this article.
Yes, but: The new results give Abivax more clinical evidence to argue that obefazimod can benefit refractory ulcerative colitis patients and that malignancy rates should be interpreted against a broader exposure-adjusted safety database. They do not remove the safety question from the story, but they give regulators and investors more context as the company prepares for a potential FDA filing.
The bottom line: The once-daily oral drug is the company’s lead asset and the main driver of its regulatory and commercial strategy. If approved, it would enter an increasingly crowded ulcerative colitis market that already includes injectable biologics such as anti-TNF, anti-integrin and IL-23 therapies, as well as oral options including JAK inhibitors and S1P receptor modulators from larger pharma groups. That puts pressure on Abivax to show not only strong efficacy, but also a differentiated safety and convenience profile.
