Abivax (NASDAQ:ABVX) said its Phase 3 ABTECT maintenance trial of obefazimod in ulcerative colitis met its primary endpoint, with company executives describing the results as a key step toward a planned U.S. regulatory filing in late 2026.
On an investor webcast following the release of top-line results, Chief Executive Officer Marc de Garidel said both the 25 milligram and 50 milligram doses of obefazimod met the primary endpoint of clinical remission and all key secondary endpoints in the 44-week maintenance study. The company reported placebo-adjusted clinical remission rates of 39.3% and 40.3% for the 25 milligram and 50 milligram doses, respectively.
Trial Design and Efficacy Results
Chief Medical Officer Fabio Cataldi said the ABTECT program included two independent eight-week induction trials. Patients who responded to active drug during induction were then randomized into the maintenance trial. Responders to 50 milligrams were assigned to remain on 50 milligrams, step down to 25 milligrams or switch to placebo. Responders to 25 milligrams either stayed on 25 milligrams or switched to placebo.
The maintenance study randomized 580 patients. Cataldi said the treatment groups were generally balanced across age, induction-modified Mayo Score and mean disease duration, though the 50 milligram cohort had a higher proportion of patients who had failed prior advanced therapies.
According to Cataldi, the placebo clinical remission rate was 10.4%, which management characterized as historically low for a re-randomized responder maintenance trial in ulcerative colitis. He said the maintenance trial completion rate was approximately 80% in both obefazimod arms, compared with 34% among induction responders re-randomized to placebo.
Both obefazimod doses also met key secondary endpoints, including:
- Endoscopic improvement
- Endoscopic remission
- Histo-endoscopic mucosal improvement
- Corticosteroid-free clinical remission
- Sustained clinical remission
De Garidel said obefazimod delivered placebo-adjusted endoscopic remission rates of 38% for the 50 milligram dose and 31% for the 25 milligram dose, describing the endpoint as one of the most clinically meaningful in ulcerative colitis.
Safety Profile
Chris Rabbat, head of global medical affairs, said treatment-emergent adverse events occurred at a higher rate in the 50 milligram group versus placebo and at a similar rate in the 25 milligram group versus placebo. Serious treatment-emergent adverse events occurred at similar rates across the three groups, and no deaths occurred in the trial.
Rabbat said serious, severe and opportunistic infections occurred at low rates across the groups. He also said there were no cases of acute pancreatitis and no reports of cardiac abnormalities suggestive of cardiac fibrosis.
On malignancies, Rabbat said the 50 milligram arm included one case each of prostate cancer, breast cancer and colonic dysplasia, all in different organ systems and all considered unrelated by study investigators. Four non-melanoma skin cancer cases were observed in the 50 milligram group, while one squamous cell carcinoma case was observed in a 25 milligram patient who had a history of skin cancer and prior exposure to azathioprine.
Rabbat said the independent data monitoring committee did not consider the numerical difference in non-melanoma skin cancer cases in the 50 milligram arm to be a safety signal. He said the findings should be viewed in the context of the underlying ulcerative colitis population, which has an elevated background risk of non-melanoma skin cancer.
Headache and Longer-Term Data
Rabbat also addressed headache rates, noting that headaches had been seen more frequently with treatment than placebo in the induction trials. In the maintenance trial, he said exposure-adjusted incidence rates of headache were similar across the three groups, and headache did not lead to study discontinuation in either obefazimod arm.
De Garidel said the maintenance findings were complemented by long-term Phase 2a/2b open-label extension data announced in May. In that study, he said patients who received 50 milligram obefazimod for two to four years and then transitioned to 25 milligrams for up to an additional three years maintained durable clinical remission and a favorable safety profile for up to seven years of treatment exposure.
Physician Perspective and Commercial Positioning
David Rubin, chief of gastroenterology, hepatology and nutrition and director of the Inflammatory Bowel Diseases Center at the University of Chicago, joined the call as an advisor to Abivax. Rubin said he had seen the data the prior day and described the study as “very positive,” particularly in a moderately to severely active ulcerative colitis population that included patients refractory to multiple prior therapies.
Rubin said the results suggest obefazimod could be relevant both as a first-line advanced therapy and as a later-line option for more refractory patients, depending on factors such as payer coverage, patient characteristics and additional subset analyses. He also said the oral, small-molecule nature of the drug may be meaningful in ulcerative colitis because inflamed colons can leak protein, potentially affecting exposure to monoclonal antibody therapies.
During the question-and-answer session, management said it expects to present additional analyses, including results by prior advanced therapy exposure and data on patients who stepped down from 50 milligrams to 25 milligrams, at future medical meetings. De Garidel said Abivax plans to file for approval with both maintenance doses.
The company also said it remains confident in its Crohn’s disease program, though Cataldi noted that enrollment has been affected by a competitive clinical trial landscape. Management said recent ulcerative colitis results and prior data suggesting potential anti-fibrotic effects could support recruitment in Crohn’s disease trials.
About Abivax (NASDAQ:ABVX)
Founded in 2013 and headquartered in Paris, France, Abivax is a clinical-stage biopharmaceutical company focused on discovering and developing novel therapies for chronic inflammatory diseases and viral infections. The company’s technology platform targets host RNA biogenesis to modulate key immune pathways, offering a differentiated approach aimed at disease modification and improved safety profiles.
Abivax’s lead clinical asset, obefazimod (ABX464), is being evaluated in ulcerative colitis and other inflammatory disorders.
