First patient dosed in the Phase 2 study of SER-109 in recurrent Clostridium difficile infection

Seres Therapeutics has enrolled and dosed the first patient in its Phase 2 clinical study of SER-109, an investigational oral microbiome therapeutic for the prevention of recurrent Clostridium difficile infection (CDI) in adults.

The objective of the Phase 2 study is to further assess the efficacy and safety of SER-109 Seres’ leading development candidate.

“Recurrent CDI is a rapidly growing problem in the US and antibiotics are currently the only FDA-approved treatment option” said Roger Pomerantz, Chairman President and CEO of Seres. “For many patients antibiotics may exacerbate the problem by inducing or prolonging an imbalance of the microbiome and creating the conditions that support disease recurrence. We are excited about evaluating the potential of SER-109 to correct the microbiome and address this critical patient need.”

SER-109 is a potentially transformative therapeutic

Mr Pomerantz continued, “The start of our Phase 2 study is an important milestone for patients and for Seres. Our earlier studies suggest that SER-109 is a potentially transformative therapeutic for tens of thousands of patients each year validating our conviction that treating dysbiosis of the microbiome enables us to address the underlying cause of disease and bring about rapid improvements in health.”

CDI is one of the top three most urgent antibiotic-resistant bacterial threats in the US according to the US Centers for Disease Control. It is responsible for the death of approximately 29,000 Americans each year. The incidence of first occurrence is between approximately 640,000 and 820,000 patients per year in the US alone. The risk of recurrence is approximately 25% and an additional 8% of patients fail to respond to antibiotics after the primary occurrence of CDI; 40% or greater after a first recurrence and more than 60% for those who have experienced two or more recurrences.

97% of patients achieved  a clinical cure after SER-109 dosing in the Phase 1b/2 study

Results from the Phase 1b/2 study of SER-109 in recurrent CDI patients showed that 87% of patients met the primary study endpoint and 97% of patients achieved a clinical cure which was defined as the absence of CDI requiring antibiotic treatment during the eight-week period after SER-109 dosing.

The Phase 2 study is a multicentre, randomised placebo-controlled study that will evaluate the efficacy and safety of SER-109. The primary outcome measure is the absence of clinically-significant CDI through eight weeks following administration of SER-109 compared to placebo.