Seres Therapeutics Announces Layoffs and Strategic Shift to Fund Phase 2 Study

Seres Therapeutics, a prominent microbiome biopharma company, has announced a significant restructuring effort aimed at conserving resources for its upcoming phase 2 study of SER-155, a promising treatment for preventing bloodstream infections in adults undergoing allogeneic hematopoietic stem cell transplant.

Workforce Reduction and Financial Strategy

The Cambridge, Massachusetts-based company revealed plans to reduce its workforce by 25%, a move that will primarily affect employees not directly involved in the preparations for the phase 2 study of SER-155. This decision is expected to result in severance costs between $1 million and $1.4 million.

Seres co-CEOs Thomas DesRosier and Marella Thorell stated, "While we advance SER-155 phase 2 study start-up activities, we continue to engage in active discussions with multiple parties seeking capital to initiate the study, and to support our broader portfolio of product candidates with applications for inflammatory diseases."

The company anticipates that these cost-cutting measures, combined with additional operational streamlining, will extend its cash runway "well into" the second quarter of 2026. This extension is crucial, as Seres' current cash reserves were projected to be depleted by March 2026.

SER-155 Development and Clinical Trial Plans

Seres Therapeutics has reported "constructive" conversations with the FDA regarding the protocol for the SER-155 phase 2 study. The trial is set to involve 248 participants, with interim results expected within 12 months of its commencement.

The focus on SER-155 represents a strategic pivot for Seres, which has been seeking additional funding to advance this asset into mid-stage clinical development. The biotherapeutic is designed to prevent bloodstream infections in adults undergoing allogeneic hematopoietic stem cell transplant, a procedure that carries significant risk of infection.

Company Background and Recent Developments

Seres Therapeutics gained recognition for developing Vowst, the first oral microbiome product to receive FDA approval as a therapeutic. The company sold the rights to this Clostridioides difficile infection therapy to its commercialization partner Nestlé Health Science a year ago.

This latest restructuring follows a previous round of layoffs in November 2023, when Seres cut approximately 160 jobs to refocus its efforts on Vowst and SER-155. The company's strategic decisions reflect the challenges faced by many biotechnology firms in balancing innovative research with financial sustainability.