Shares of Seres Therapeutics (MCRB) fell 23% after the company reported topline results from a SER-287 Phase 1b placebo-controlled induction study in 58 patients with mild-to-moderate Ulcerative Colitis (UC), who were failing current therapies.
Study data demonstrated that SER-287, a microbiome therapy containing a consortium of live bacterial spores, resulted in a benefit in clinical remission rates, and also an improvement in mucosal appearance by endoscopy.
Management noted that clinical remissions and endoscopic improvements of 30% versus the placebo for the highest SER-287 dose were positive, but investors were disappointed that 60% of patients saw a clinical response in both the placebo and SER-287 arms of the study.
The SER-287 safety and tolerability profile, a co-primary study endpoint, demonstrated no clinically significant safety findings. The lack of safety issues gives the company more leeway with the FDA because there is an unmet need for ulcerative colitis treatments.
Full microbiome study results, a co-primary endpoint, are expected in the coming months.
Seres said it will meet with the FDA to discuss the next study -- it's unclear which phase will be necessary.
Seres recently initiated a Phase 3 study of SER-109 treating patients with multiply recurrent Clostridium difficile (C. difficile) infection Top-line data from the Pase 1 study of SER-162 treating primary C. difficile infection are expected in early 2018. Seres will use -287 data to help develop SER-301 for IBD.
Seres has a market capitalization of just under $500 million after today's decline.