Seres Therapeutics to Initiate New SER-109 Phase 2 Study

Seres Therapeutics, a leading microbiome therapeutics platform company, has announced plans to initiate a new SER-109 phase 2 clinical study (ECOSPOR III) in patients with multiply recurrent Clostridium Difficile (C. Difficile) infection. The ECOSPOR III study design was finalized following a positive Type B meeting with the US Food and Drug Administration (FDA). In a separate announcement, Seres reported fourth quarter and full year 2016 financial results and provided an update on multiple ongoing microbiome clinical programmes.

Seres plans to initiate a new SER-109 clinical study in approximately 320 patients with multiply recurrent C. Difficile infection. Study participants will be randomized 1:1 between SER-109 and placebo. To ensure accurate measurement of C. Difficile infection, diagnosis of recurrent C. Difficile infection for both study entry and for endpoint analysis will be confirmed by C. Difficile cytotoxin assay. Patients in the SER-109 arm will receive a total SER-109 dose, administered over three days, approximately 10-fold higher than the dose used in the prior ECOSPOR study. ECOSPOR III will evaluate patients for 24 weeks and the primary endpoint will compare the C. Difficile recurrence rate in subjects who receive SER-109 verses placebo at up to eight weeks after dosing. The FDA has agreed that this new trial may qualify as a pivotal study with achievement of a persuasive clinical effect and addressing FDA requirements, including clinical and statistical factors, an adequately sized safety database, and certain CMC parameters.