ABTECT Maintenance Data Show Durable Remission in UC, With Remo Panaccione, MD

Part 2 of the phase 3 ABTECT maintenance trial found that obefazimod sustained clinical remission through week 44 in ulcerative colitis (UC) patients, including those who had not initially responded to induction therapy. The results build on positive Part 1 data and add to a growing safety database ahead of the company's planned US Food and Drug Administration (FDA) new drug application (NDA) submission.

"These results that we'll probably be talking about today are really building upon very impressive induction data, where we saw placebo-adjusted treatment differences for the primary endpoint of clinical remission, which was quite substantial," Remo Panaccione, MD, professor of medicine and director of the IBD Clinic at the University of Calgary, said in an interview with HCPLive.

How Large Was the ABTECT Maintenance Population?

Panaccione noted the onset of benefit was rapid, "with separation from placebo as early as one week for symptomatic response and week two for symptomatic remission." Part 1 of the maintenance study enrolled 580 patients who had responded to induction and entered the randomized, placebo-controlled maintenance phase, while Part 2 added 633 patients who had either not responded during induction or lost response during maintenance.

"This study also included a substantial portion of patients who were difficult to treat," Panaccione said. "In particular, it enrolled the largest cohort of patients with an inadequate response to a JAK inhibitor that we've ever studied in phase three clinical trials." He noted JAK inhibitor exposure typically signals later-line therapy, where patients tend to respond less robustly than treatment-naive patients or those exposed only to monoclonal antibodies.

Both the 25 mg and 50 mg doses met the primary endpoint of clinical remission at week 44, with remission rates around 51% compared to 10% with placebo. "This 40% difference, which is the largest placebo-adjusted difference that we've seen in a phase three trial, part of that may have been due to the fact that the placebo rate was quite low, and that speaks usually to the difficult-to-treat patient population," Panaccione said. Among initial non-responders continued on 50 mg, approximately 37% achieved remission and >60% achieved response; among those who relapsed on 25 mg and were escalated to 50 mg, remission was recaptured in approximately 56%.

What Did Endoscopic Remission Rates Show?

For Panaccione, the endoscopic data carried particular weight. "To get into the trial, the patients needed a Mayo endoscopy score of either two or three, signaling moderate to severe endoscopic disease. To achieve endoscopic remission, you needed to go all the way from that down to an endoscopic score of zero," he said. "This is important because this is a highly objective measure of drug efficacy."

Endoscopic remission was achieved in 41.5% of patients on 25 mg and 47.7% on 50 mg, compared to 10% with placebo. "These are amongst the highest endoscopic remission rates that we've seen, and this strong endoscopic remission data really signifies or signals the potential of this drug in moderate to severe ulcerative colitis," Panaccione said. Both doses also met key secondary endpoints, including endoscopic improvement, histologic-endoscopic mucosal improvement, and steroid-free remission, with no concerning safety signals through 44 weeks.

Is Obefazimod's Safety Profile Holding Up With Longer Exposure?

Addressing the drug's safety profile, Panaccione cautioned against over-reading early signals. "When the induction data was first released publicly, there were a few malignancies in the 50 mg dose, and I think that was a little bit misinterpreted," he said. "When we're interpreting rare safety events such as malignancy, it's important not to focus solely on the raw numbers... simple case counts can be really misleading, particularly when the amount of treatment exposure differs amongst groups."

He explained that the 50 mg group had both the greatest cumulative exposure and the most treatment-refractory patients, which would naturally be expected to produce more events. "The important thing is to look at exposure-adjusted incidence rates, and that's a more appropriate way to look at safety in general," Panaccione said.

Across the phase 2 and phase 3 programs, exposure totaled >1,700 patient-years. Rates of non-melanocytic skin cancer were consistent with published malignancy rates in UC, Panaccione said, noting that a prostate cancer and a breast cancer observed in the 50 mg group were not rare cancers and occurred in patients where they would be expected. "Certainly, the available data doesn't suggest a dose-dependent malignancy signal with obefazimod," he said. With phase 2 data now extending beyond four years, Panaccione characterized the overall benefit-risk profile as favorable.

Editors' note: Panaccione has relevant disclosures with Abbott, AbbVie, Abivax, Alimentiv, Amgen, AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, Eli Lilly, Ferring, Galapagos, Gilead Sciences, Janssen, Merck, Novartis, Pfizer, Takeda, and others.

References

1. Abivax announces landmark Phase 3 ABTECT maintenance trial results evaluating obefazimod in moderately to severely active ulcerative colitis. News release. Abivax. June 1, 2026. Accessed August 19, 2026. https://www.globenewswire.com/news-release/2026/06/01/3304711/0/en/abivax-announces-landmark-phase-3-abtect-maintenance-trial-results-evaluating-obefazimod-in-moderately-to-severely-active-ulcerative-colitis.html

2. Abivax reports positive ABTECT maintenance Part 2 results for obefazimod, demonstrating meaningful clinical benefit in refractory ulcerative colitis patients and strengthening the Phase 3 maintenance safety database. News release. Abivax. June 29, 2026. Accessed August 19, 2026. https://ir.abivax.com/news-releases/news-release-details/abivax-reports-positive-abtect-maintenance-part-2-results/