4 March 2021 - - US-based microbiome therapeutics platform company Seres Therapeutics, Inc. (NASDAQ: MCRB) has achieved target enrollment of the Phase 2b ECO-RESET clinical study of SER-287 in patients with mild-to-moderate ulcerative colitis in both the US and Canada, the company said.

SER-287, Seres' second microbiome therapeutic to reach late-stage clinical trials following a successful Phase 3 readout for SER-109, could represent a new therapeutic paradigm for UC by targeting underlying biological drivers of the disease.

The results of this study will inform Seres' broader development efforts in ulcerative colitis and other programs that target modulation of host inflammation and immunity.

The Phase 2b ECO-RESET study (Clinicaltrials.gov identifier: NCT03759041) is a multicenter, randomized, placebo-controlled study which has enrolled the targeted 201 patients with active mild-to-moderate UC.

Two groups of patients are receiving different doses of SER-287, both following pre-conditioning with a short course of oral vancomycin.

A third group is receiving placebo. The study's primary endpoint will evaluate clinical remission measured after 10 weeks of SER-287 administration. Endoscopic improvement will be measured as a secondary efficacy measure.

Based upon feedback obtained from the US Food and Drug Administration on the SER-287 Phase 2b study design, Seres believes the study could serve as one of two required pivotal trials supporting a Biologics License Application.

The company expects to share topline clinical data from ECO-RESET in mid-2021.

Mild-to-moderate UC is the most common form of the disease, representing a majority of the patient population in the US First-line therapies for UC are only modestly effective.

Non-responders have limited treatment options because potent immunosuppressive therapies have serious side effects which may be hard to justify in patients with mild-to-moderate disease.

An unmet need exists for an effective, safer alternative therapeutic approach for mild-to-moderate UC patients that is not immunosuppressive.

SER-287, an oral microbiome therapeutic candidate consisting of a consortium of highly purified Firmicute spores, is designed to normalize the gastrointestinal microbiome of individuals with UC.

Preclinical colitis animal models and in vitro screens provide evidence that SER-287 administration has the potential to reduce pathology and modulate inflammatory and immunological functional pathways.

SER-287 has been granted Fast Track Designation by the FDA for the induction and maintenance of clinical remission in adult subjects with active mild-to-moderate UC. SER-287 has been designated an Orphan Drug for pediatric UC by the FDA.

Seres Therapeutics, Inc., (NASDAQ: MCRB) is a leading microbiome therapeutics platform company developing a novel class of multifunctional bacterial consortia that are designed to functionally interact with host cells and tissues to treat disease.

Seres' SER-109 program achieved the first-ever positive pivotal clinical results for a targeted microbiome drug candidate and has obtained Breakthrough Therapy and Orphan Drug designations from the FDA.

The SER-109 program is being advanced for the treatment of recurrent C. difficile infection and has potential to become a first-in-class FDA-approved microbiome therapeutic.

Seres' SER-287 program has obtained Fast Track and Orphan Drug designations from the FDA and is being evaluated in a Phase 2b study in patients with active mild-to-moderate UC.

Seres is evaluating SER-401 in a Phase 1b study in patients with metastatic melanoma, SER-301 in a Phase 1b study in patients with ulcerative colitis, and SER-155 to prevent mortality due to gastrointestinal infections, bacteremia and graft versus host disease.