FDA Grants Review, Sets PDUFA Date for SER-109

The US Food and Drug Administration (FDA) has accepted a Biologics License application (BLA) for SER-109, live microbiome therapeutic for the prevention of recurrent Clostridioides difficile infection (rCDI).

The FDA granted SER-109, developed by Seres Therapeutics, priority review and set a Prescription Drug User Fee Act (PDUFA) action data of April 26, 2023, but are not planning to hold an advisory committee meeting on the application.

The acceptance is based on multiple completed development programs, including ECOSPOR III, a multicenter randomized placebo controlled study and ECOSPOR IIV, an open-label extension of the previous study.

The first study included 182 adult patients with rCDI, with results showing 88% of the SER-109 were free from recurrence 8 weeks post treatment and 79% were free at 24 weeks, compared to 53% for the placebo group.

Then in the open-label extension, the investigators examined 263 adult patients with rCDI at the commercial dose of SER-109. Topline results for this study show the safety profile was well-tolerated with a 91% sustained clinical response at 8 weeks. The investigators also found 86% of patients treated with SER-109 experienced sustained clinical response at week 24.

"We’re aiming to strengthen the body’s defenses against the return of C. difficile infection by repairing the microbiome,” said Lisa von Moltke, M.D., Chief Medical Officer at Seres, in a statement. “The clinical evidence to date from both ECOSPOR III and ECOSPOR IV continues to support the potential use of SER-109 to reduce the suffering and health risks inflicted by repeated occurrences of this incredibly difficult-to-treat disease.”

Seres presented data from both studies during the 2022 American College of Gastroenterology (ACG) Annual Meeting in Charlotte.