The U.S. Food and Drug Administration (FDA) has approved an investigational new drug (IND) application for ABX464, Abivax’s treatment candidate for ulcerative colitis (UC), allowing the company to expand its Phase 2b trial assessing the medicine’s safety and efficacy to the U.S.

The trial, called ABX464-103 (NCT03760003), is ongoing in 15 European countries and in Canada. It’s expected to enroll up to 232 adults with moderate-to-severe UC, testing various daily doses (25 mg, 50 mg, and 100 mg capsules) against a placebo for 16 weeks.

Patient enrollment is still underway at several existing sites, and expected to open at U.S. sites in the coming months. More information is available here.

“We are very excited about the green light from the FDA, which is a very important milestone in Abivax’s global development strategy for our lead compound, ABX464,” Hartmut J. Ehrlich, MD, chief executive officer of Abivax, said in a press release.

“By expanding the ongoing … study of ABX464 to the U.S., Abivax is aiming to make this new potential treatment option available to a substantial number of UC patients in need of new therapeutic solutions,” Ehrlich said.

ABX464 is an oral small molecule with a new mechanism of action. It is designed to promote the production of a microRNA molecule (miRNA-124) that has strong anti-inflammatory properties. MicroRNAs are tiny RNA molecules that control the expression of several genes; RNA molecules can serve as a template for proteins produced in gene expression.

Abivax recently presented data from an open-label extension study (NCT03368118), called ABX464-102, showing that 75% of patients with moderate-to-severe UC who failed to respond to other treatments attained clinical remission — became symptom-free — after  one year of treatment with ABX464 (daily 50 mg capsules).

This long-term study included patients from a previous double-blind and placebo-controlled Phase 2a trial (NCT03093259), called ABX464-101, assessing the safety and efficacy of ABX464 in UC patients who were intolerant or failed to respond to immunomodulators, anti-TNF biologics, Entyvio (vedolizumab), and/or corticosteroids.

In all trials, ABX464 was found to be safe and well-tolerated. The most common adverse events reported include headache, abdominal pain, and diarrhea. Most of these events were mild or moderate in severity, with no serious drug reactions reported in any of the studies.

“I am pleased that this promising drug candidate can now move forward with Phase 2b testing in the U.S. Based on the data from previous trials, ABX464 has the potential to address the high unmet medical need of UC patients in the U.S. and worldwide, with many of them not responding or losing responsiveness to currently available treatments,” said William Sandborn, MD, director of the Inflammatory Bowel Disease (IBD) Center at the University of California San Diego Health and a principal trial investigator.

ABX464 is also being investigated in a Phase 2a trial (NCT03813199) in people with rheumatoid arthritis. A Phase 2a (NCT03905109), called ABX464-201, assessing the safety and efficacy of ABX464 in patients with moderate-to-severe, active Crohn’s disease is expected to start later this year.