Seres Therapeutics Implements Austerity Drive Following Strategic Pivot

Seres Therapeutics stops Phase 2 SER-155 investment and reduces workforce by 30% to preserve capital, refocusing on early-stage immunology programs.

In a significant strategic shift, Seres Therapeutics has halted investment in its clinical Phase 2 study for SER-155, a program once considered a key pipeline asset. The biotechnology firm is now enacting a substantial workforce reduction, cutting approximately 30% of its positions, as it seeks to extend its financial runway and refocus its research priorities.

Capital Preservation and Pipeline Reallocation

The company’s decision to cease funding for the SER-155 study, which targeted patients following allogeneic hematopoietic stem cell transplantation (allo-HSCT), comes shortly after submitting the final protocol to the U.S. Food and Drug Administration. Management is redirecting resources toward earlier-stage programs focused on inflammatory and immune diseases. These drastic cost-cutting measures are projected to extend Seres’s funding horizon into the third quarter of 2026.

Concurrently, the leadership team is actively pursuing strategic partnerships or alternative financing avenues to enable the future development of its more advanced drug candidates.

Strategic Shift Follows Asset Divestment

This new direction follows the completion of a major transaction in September 2024: the sale of the VOWST business to Nestlé Health Science. VOWST had been the first FDA-approved oral microbiome therapeutic. Capital from that divestiture was initially earmarked to primarily fund the advancement of SER-155.

Despite encouraging Phase 1b results that demonstrated a significant reduction in bloodstream infections among transplant patients, the current financial reality has compelled the company to prioritize stringent cost control over the program's immediate progression.

Future Hinges on Partnerships and Upcoming Data

The path forward for Seres Therapeutics now largely depends on its ability to secure new collaborative agreements for its clinical programs. A critical milestone is anticipated next year, with initial data from an independent, investigator-led study of SER-155 expected in the second quarter of 2026. In the interim, market attention will likely focus on the progression of the company’s early-stage pipeline in the immunology space.