Seres Therapeutics Announces FDA Clearance of IND for Investigational Microbiome Therapeutic for the Prevention of Antibiotic-Resistant Bacterial Infections and GvHD

In collaboration with Memorial Sloan Kettering Cancer Center, Seres will now advance SER-155 into a Phase 1b clinical study

Seres Therapeutics, Inc. (Nasdaq: MCRB), a leading microbiome therapeutics company, announces the U.S. Food and Drug Administration (FDA) has indicated studies for SER-155 may proceed under an Investigational New Drug (IND) application. SER-155 is an investigational oral, rationally-designed, cultivated microbiome therapeutic designed to reduce the incidence of gastrointestinal antibiotic-resistant bacterial infections, bacteremia and graft-versus-host disease (GvHD) in immunocompromised patients, including patients receiving allogeneic hematopoietic stem cell transplantation (HSCT). Prior published studies by Memorial Sloan Kettering Cancer Center collaborators indicate that HSCT patients with a dysbiotic microbiome are at substantially increased risk for bacterial infections and poor outcomes.

“Antibiotic-resistant bacterial infections represent one of the most pressing public health threats with significant implications for HSCT patients and, more broadly, other cancer and immunocompromised patients,”

said Matthew Henn, Ph.D., Chief Scientific Officer at Seres.

“SER-155 represents a novel microbiome technology with the potential to address antibiotic-resistant bacterial bloodstream infections and further to modulate host immunomodulatory responses to decrease graft-versus-host disease.”

The SER-155 Phase 1b study is designed to include approximately 70 patients in both an open-label and a randomized, double-blind, placebo-controlled cohort that will evaluate safety and tolerability before and after HSCT. Additionally, the engraftment of SER-155 bacteria (a measure of pharmacokinetics) and the efficacy of SER-155 in preventing infections and GvHD will be evaluated. Seres developed SER-155 with support from a CARB-X grant, including financial and operational support into Phase 1b. Seres fully owns worldwide rights for commercialization of SER-155.

“This milestone represents another exciting opportunity to support patients through Seres microbiome therapeutic candidates and illustrates the potential for microbiome therapeutics to change how disease is treated for immunocompromised patients,”

said Eric Shaff, Chief Executive Officer at Seres.

“Our commitment is to provide more options for people living with serious diseases, and we look forward to an eventful year with additional clinical milestones from our investigational pipeline.”

Antibiotic-resistant infections and GvHD are frequent and serious complications of organ and stem cell transplantation, which can lead to mortality. Additionally, such infections can lead to medical complications in immunocompromised patients more broadly. Antibiotics used to treat infections in HSCT individuals are not always effective and can have significant side effects. Current therapies for the prevention of GvHD rely on broad immunosuppression, which increases the risk of infection, and has limited efficacy for a significant proportion of patients.

About SER-155
SER-155, an oral consortium of cultivated bacteria, is a microbiome therapeutic candidate intended to advance into clinical development. SER-155 is designed using microbiome biomarker data from human clinical data, human cell-based assays, and in vivo disease models, with the aim to decrease infection and translocation of antibiotic-resistant bacteria in the gastrointestinal tract and modulate host immune responses to decrease GvHD. The rationale for this program is based in part on published clinical evidence from Seres’ collaborators at Memorial Sloan Kettering Cancer Center showing that allogeneic HSCT patients with decreased diversity of commensal microbes are significantly more likely to die due to infection and/or lethal GvHD. SER-155 was developed using Seres’ reverse translational discovery platform to reduce morbidity and mortality due to gastrointestinal infections, bacteremia and GvHD in immunocompromised patients, including in patients receiving allogeneic HSCT or solid organ transplants.