Seres Therapeutics August 2025 slides: SER-155 shows 77% infection reduction

Introduction & Market Context

Seres Therapeutics (NASDAQ:MCRB) presented its investor slides for August 2025, highlighting significant progress in its clinical pipeline following the strategic sale of its VOWST asset. The company’s stock closed at $14.28 on August 5, down 3.38% for the day, but has shown volatility throughout the year with a 52-week range of $6.53 to $26.40.

The presentation comes after a strong financial turnaround in Q1 2025, when the company reported net income of $32.7 million compared to a net loss of $32.9 million in the same quarter last year, largely driven by milestone payments from its VOWST asset sale to Nestle (NSE:NEST).

Executive Summary

Seres is positioning itself as a pioneer in microbiome therapeutics, with a validated platform highlighted by the FDA approval and subsequent sale of VOWST, the first-ever oral live microbiome therapeutic. The company’s current focus is on advancing SER-155, which has demonstrated impressive clinical results in preventing bloodstream infections in allogeneic hematopoietic stem cell transplant (allo-HSCT) patients.

As shown in the following overview of the company’s strategy to transform patient outcomes:

The company has established a strong foundation with the VOWST approval and subsequent asset sale, providing cash runway into Q1 2026. With positive Phase 1b data for SER-155 showing a 77% relative risk reduction for bloodstream infections, Seres is now advancing this program as its anchor biotherapeutic with blockbuster potential.

SER-155 Clinical Results

The most compelling data from Seres’ presentation centers on SER-155’s efficacy in preventing bloodstream infections in allo-HSCT patients. The Phase 1b study demonstrated a statistically significant 77% relative risk reduction in bacterial bloodstream infections compared to placebo.

The following slide illustrates the key efficacy results from the SER-155 clinical trial:

This reduction in infections was accompanied by significantly lower mean cumulative exposure to systemic antibacterials and antimycotics, suggesting SER-155 could potentially reduce antibiotic use in this vulnerable patient population.

The detailed data showed that only 10% of SER-155-treated subjects experienced confirmed bloodstream infections, compared to 42.9% in the placebo group (p=0.0423), as illustrated in this chart:

Beyond infection prevention, SER-155 demonstrated positive effects on epithelial barrier function, with fecal albumin levels remaining low in treated subjects throughout the peri-transplant period, suggesting barrier protection:

The treatment was also associated with lower plasma concentrations of inflammatory cytokines relative to placebo, indicating an anti-inflammatory effect:

Financial Position & VOWST Asset Sale

The VOWST asset sale, completed on September 30, 2024, has significantly strengthened Seres’ financial position. The transaction provided an immediate $100 million upfront payment (less approximately $20 million in net obligations), along with additional milestone payments.

The following slide details the financial terms of the VOWST asset sale:

This strategic transaction has already yielded tangible financial benefits, as evidenced by the company’s Q1 2025 earnings report, which showed a net income of $32.7 million largely attributable to a $50 million installment payment from Nestle received in January 2025. The company also reported reduced R&D expenses of $11.8 million (down from $19.5 million in Q1 2024) and G&A expenses of $11.9 million (down from $14.9 million in Q1 2024), indicating effective cost management.

As of March 31, 2025, Seres reported cash and cash equivalents of $58.8 million, with the company projecting runway into Q1 2026.

Commercial Potential & Market Opportunity (SO:FTCE11B)

Seres believes SER-155 has blockbuster commercial potential, driven by significant unmet needs in preventing infections in transplant patients. The company estimates there are approximately 40,000 transplants performed annually worldwide, representing a substantial market opportunity.

The following slide illustrates the commercial potential for SER-155:

Healthcare providers and payers have expressed strong interest in SER-155’s potential to reduce infection risk. According to the company’s market research, clinicians are seeking therapies that can reduce bloodstream infections, decrease systemic antibiotic use, and reduce the incidence of febrile neutropenia – all areas where SER-155 has shown promise.

The company also highlighted a comparison to an existing viral prophylaxis drug with 2024 sales of $785 million, suggesting a benchmark for SER-155’s market potential.

Strategic Initiatives & Future Pipeline

Beyond SER-155 for allo-HSCT patients, Seres is exploring multiple additional indications that could expand the commercial opportunity. The company’s microbiome platform has potential applications in autologous HSCT (approximately 60,000 transplants worldwide annually) and broader leukemia indications (approximately 500,000 cases globally).

Seres is also advancing SER-147 for preventing infections in chronic liver disease and exploring applications in inflammatory bowel disease (IBD) with SER-603.

The company’s VOWST approval has validated its microbiome therapeutic approach, as highlighted in this slide:

Forward-Looking Statements

Seres has submitted a Phase 2 study protocol for SER-155 to the FDA in May 2025 and is awaiting feedback to finalize the protocol. The company is also exploring partnership opportunities to secure additional capital for advancing SER-155 and other live biotherapeutic candidates.

The following summary slide outlines the company’s path forward:

During the Q1 2025 earnings call, CEO Eric Schaff stated, "We are making significant progress advancing SER-155 bolstered by encouraging clinical and mechanistic data," while CFO Mirella Thorel emphasized the company’s disciplined financial management approach.

With its validated platform technology, promising clinical data for SER-155, and strengthened financial position following the VOWST asset sale, Seres Therapeutics appears well-positioned to advance its microbiome therapeutics pipeline while exploring strategic partnerships to maximize the value of its platform.

Full presentation:

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