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.

“We are pleased to have received highly constructive guidance from the FDA regarding further SER-109 clinical development and we plan to initiate a new clinical study as soon as possible,” said Roger J. Pomerantz, managing director, president, chief executive officer and chairman of Seres. “Our prior SER-109 studies provided important new biological and clinical data that have advanced our pioneering microbiome therapeutic efforts. Based on our learnings and dialogue with the FDA, we believe that we are now positioned to initiate a robust clinical study that may provide the basis for SER-109 approval. There is an urgent need for improved treatments for C. Difficile infection, and we believe SER-109 has great potential to address the underlying cause of the disease and become the first approved microbiome therapeutic in this new field of medicine.”