Seres Therapeutics Publishes Mechanism Data for VOWST in Nature Medicine, Validates Live Biotherapeutics Platform
Key Insights
Seres Therapeutics published two studies in Nature Medicine and Journal of Infectious Diseases demonstrating VOWST's mechanism of action through microbiome (search) restoration and metabolite production that inhibits C. difficile (search) growth.
The research confirmed that higher VOWST dosing enhances therapeutic bacterial engraftment and significantly alters intestinal microbiome (search) composition, including increased secondary bile acids and fatty acids.
Data from the ECOSPOR IV Phase 3 trial showed consistent disease etiology and VOWST efficacy across both first and multiply recurrent CDI patient populations.
Seres Therapeutics announced the publication of two manuscripts in Nature Medicine and the Journal of Infectious Diseases that provide new insights into the functional mechanism and clinical impact of VOWST, the first FDA-approved oral microbiome (search) biotherapeutic. The publications validate the company's Live Biotherapeutics Products approach and inform the continued development of its pipeline, including lead candidate SER-155.
VOWST Mechanism Confirmed Through Microbiome Analysis
The Nature Medicine article, titled "The impact of an oral purified microbiome (search) therapeutic on the gastrointestinal microbiome," confirmed Seres' pharmacological hypotheses from earlier VOWST studies. The research demonstrated that higher VOWST dosing was associated with enhanced pharmacokinetics, as assessed by faster and more robust therapeutic species engraftment in the gut.
Treatment significantly altered the composition of the intestinal microbiome (search) and microbe-associated metabolites, including decreased primary and increased secondary bile acids, as well as elevated short- and medium-chain fatty acids. These functional changes inhibit C. difficile (search) spore germination and vegetative growth. In vitro analyses confirmed that VOWST batches induced production of these metabolites that disrupt C. difficile life cycle and growth.
Consistent Efficacy Across Patient Populations
A complementary publication in the Journal of Infectious Diseases, titled "Comparability of Gastrointestinal Microbiome (search) and Bile Acid Profiles in Patients With First or Multiply Recurrent Clostridioides difficile Infection (search)," reported a post hoc analysis of the ECOSPOR IV Phase 3 trial. The study evaluated differences in gastrointestinal microbiome and bile acid profiles between patients experiencing first recurrence C. difficile (search) infection versus multiply recurrent infection.
The data demonstrate that the underlying functional disease etiology is consistent in both first and multiply recurrent CDI patient populations, with VOWST demonstrating similar efficacy and drug pharmacology across the broad patient population.
Platform Validation Supports Pipeline Development
"We are thrilled to see these high-impact publications highlighting the important role biotherapeutics that comprise commensal bacteria may have in treating human disease," said Matthew Henn, Ph.D., Chief Scientific Officer at Seres Therapeutics. "These data provide important clinical translation and further demonstrate the promise of live biotherapeutics to target specific microbiome (search) functions that are linked to serious disease, including those that are not effectively treated with other drug modalities."
The underlying data supporting these publications was developed using Seres' MbTx platform, which provides high-resolution assessment of drug pharmacology and functional mechanism of action. These data on bacterial function and pharmacology anchored the preclinical development of SER-155.
SER-155 Shows Promise in Stem Cell Transplant Patients
In a randomized, placebo-controlled Phase 1b study evaluating SER-155 in patients undergoing allogeneic hematopoietic stem cell transplant, SER-155 reduced bacterial bloodstream infections (search) by 77% and significantly lowered systemic antibiotic use and febrile neutropenia (search). SER-155 has received Breakthrough Therapy designation for the reduction of bloodstream infections in adults undergoing allo-HSCT and Fast Track designation for reducing the risk of infection and graft-versus-host disease (search).
Exploratory biomarker data presented at medical meetings has further supported the therapy's intended mechanisms and demonstrate the broader potential of live biotherapeutics in inflammatory and immune-mediated diseases. The company intends to evaluate SER-155 and other cultivated live biotherapeutic candidates in other medically vulnerable patient populations including autologous-HSCT patients, cancer patients with neutropenia, CAR-T recipients, individuals with chronic liver disease, solid organ transplant recipients, as well as patients in intensive care units and long-term acute care facilities.
VOWST was the first-ever oral microbiome (search) biotherapeutic licensed by the FDA, with approval in April 2023 for the prevention of recurrent Clostridioides difficile infection (search). The therapy was sold to Nestlé Health Science (search) in September 2024.