Seres Therapeutics, Inc. · NASDAQ:MCRB
Seres Therapeutics — Investor Presentation (November 2025)
37 slides from Seres Therapeutics's investor presentation, Nov 5, 2025
Slide 1: Seres Therapeutics Investor Presentation November 2025
Seres Therapeutics Investor Presentation November 2025 Exhibit 99.2
Slide 2: Disclaimers: Forward Looking Statements
Disclaimers Forward Looking Statements This communication contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this communication that do not relate to matters of historical fact should be considered forward-looki
Slide 3: Transforming patient outcomes using proprietary consortia of live biotherapeutics
Transforming patient outcomes using proprietary consortia of live biotherapeutics Strong Foundation Validated platform highlighted by VOWST® FDA approval as first ever oral microbiome therapy with outstanding clinical results VOWST asset sale strengthened balance sheet and streamlined organization C
Slide 4: Validated therapeutic modality and platform: VOWST FDA approval
Validated therapeutic modality and platform: Seres pioneered the development and FDA approval of VOWST as the first-ever oral live microbiome therapeutic FDA approved (April 2023) to prevent the recurrence of C. difficile infection in adults Approximately 88% sustained clinical response rate (C. dif
Slide 5: VOWST asset sale to Nestle Health Science completed in September 2024
VOWST asset sale to Nestle Healh Science completed in September 2024: transformational for Seres – provided resources to support SER-155 development KEY FINANCIAL TERMS VOWST asset purchase agreement provided infusion of capital to support SER-155 development Asset sale extended operational runway R
Slide 6: The gut microbiome has substantial untapped therapeutic potential
The gut microbiome has substantial untapped therapeutic potential to both prevent and treat diseases The genetic content of the microbes living within and on your body is at least 100-fold greater than that contained in the human genome Microbes co-evolved for millions of years with and are integral
Slide 7: Disrupted gastrointestinal microbiome is linked to infections and disease
Disrupted gastrointestinal microbiome is mechanistically linked to infections and disease Impacted Biology & Disease Relevance Increased pathogen abundance, in combination with impaired barrier integrity and decreased immune function… …enables bacterial and antigen translocation leading to infection
Slide 8: Consortia of live commensal bacteria can be used as therapeutics
Consortia of live commensal bacteria can be used as therapeutics Change in microbiome function Bile acids Short-chain fatty acids Tryptophan metabolites Other Restructure microbiome composition Engraftment of drug strains Disrupted Microbiome with functional deficiencies (Disease susceptible) Change
Slide 9: Well tolerated safety profile reduces development risk
Seres’ biotherapeutics and pipeline candidates are expected to have well tolerated safety profile, reducing development risk Sources: Nanayakkara et al, CA Cancer J Clin 2021; Penack et al, Blood Adv 2020; Zheng et al, Infect Dis Ther 2021 Based on GI bacteria naturally found in healthy humans, and
Slide 10: Initial focus is preventing infections in allo-HSCT; potential is broad
Seres’ initial focus is preventing infections in allo-HSCT; potential is broad Allo-HSCT Survival by microbiome diversity Lower microbiome diversity post allo-HSCT is associated with increased blood stream infections and decreased overall survival Autologous HSCT Survival by microbiome diversity Low
Slide 11: Near-term focus on SER-155 as anchor biotherapeutic program
Near-term focus on SER-155 as anchor biotherapeutic program; constructive FDA engagement supported by Breakthrough Therapy and Fast Track designations Program Lead Indication & Development Stage Therapeutic Objectives Potential Additional Indications SER-155 Allogeneic HSCT: Phase 1b Cohort 2 (place
Slide 12: Allo-HSCT regimen can result in infectious consequences and increased mortality
Allo-HSCT regimen can result in infectious consequences and increased mortality Sources: CIBMTR 2023 US summary slides; Passweg et al BMT 2025; Penack et al, Blood Adv 2020; Khan et al, Blood 2021; Peled et al, NEJM 2020; Stein-Thoeringer et al, Science 2019; Bleakley & Riddell, Nat Rev Cancer 2004
Slide 13: Bloodstream infections are a leading cause of death post-transplant
Bloodstream infections (BSIs) are a leading cause of death post-transplant and are increasing in incidence BSI risk increasing due to recent adoption of post-transplant cyclophosphamide (PTCy) for GvHD prophylaxis BSI prevalence high despite standard of care use of antibacterial prophylaxis Majority
Slide 14: Standards of care to prevent bloodstream infections are inadequate
Standards of care to prevent bloodstream infections in allo-HSCT patients are inadequate and decreasing in efficacy * ASCO: American Society of Clinical Oncology; IDSA; Infectious Diseases Society of America; EBMT: formerly known as the European Society for Blood and Marrow Transplantation; PTCy: po
Slide 15: SER-155 Phase 1b study design in adult allo-HSCT recipients
SER-155 Phase 1b study evaluated safety, pharmacology, and efficacy in adult allo-HSCT recipients SER-155 COHORT 1 Open-label (n=15 enrolled) COHORT 2 Placebo-controlled 1:1 (n=45 enrolled) SER-155 Placebo results reported May 2023 results announced Sept. 2024 Primary Endpoints: Safety and tolerabil
Slide 16: SER-155 Safety: generally well tolerated with no treatment-related SAEs
SER-155 Safety: SER-155 was generally well tolerated with no treatment-related SAEs Treatment-emergent adverse events (TEAEs) All but one subject in the placebo arm experienced at least 1 TEAE Most common for SER-155 treated subjects (≥50% and with Δ ≥5% greater than placebo): diarrhea (86% vs. 74%
Slide 17: SER-155 Efficacy: 77% relative risk reduction in bacterial BSIs
SER-155 Efficacy: SER-155 associated with 77% relative risk reduction in bacterial BSIs and reduction in systemic antibiotic exposure Bloodstream infections Significant decrease in bacterial bloodstream infections in SER-155-treated subjects vs. placebo with 77% relative risk reduction Numerically l
Slide 18: Bloodstream infections from HSCT Day 0 to Day 100
Bloodstream infections from HSCT Day 0 to Day 100: Lower incidence in SER-155 treated subjects vs. placebo Bloodstream infections from Day 0 to Day 100 (# patients) SER-155 n=20 n (%) Placebo n=14 n (%) Subjects with confirmed BSI 2 (10.0) 6 (42.9) 95% confidence interval (1.2, 31.7) (17.7, 71.1) CI
Slide 19: Cumulative exposure to systemic antibacterials / antimycotics through Day 100
Cumulative exposure to systemic treatment antibacterials / antimycotics through HSCT Day 100: Lower incidence in SER-155 treated subjects vs. placebo Cumulative Antibacterial or Antimycotic Exposure (HSCT Days) SER-155 n=20 n (SD) Placebo n=14 n (SD) Mean (SD) 9.2 (5.44) 21.1 (20.31) Median 9.0 14.0
Slide 20: Cumulative exposure rate to systemic antibacterials / antimycotics through Day 100
Cumulative exposure rate to systemic treatment antibacterials / antimycotics through HSCT Day 100: Lower incidence in SER-155 treated subjects vs. placebo Cumulative Antibacterial or Antimycotic Exposure Rate SER-155 n=20 Rate (SD) Placebo n=14 Rate (SD) Mean (SD) 0.090 (0.0530) 0.305 (0.2898) Media
Slide 21: SER-155 Pharmacodynamics: Phase 1b measurements support mechanism of action
Measurements on Ph1b clinical study Preclinical Optimization SER-155 Pharmacodynamics: Phase 1b study included multiple measures of drug pharmacodynamics which provide support for the intended biological activity SER-155 Mechanism of Action Targets Concentration of fecal albumin in subject stool, re
Slide 22: SER-155 Pharmacodynamics: pathogen domination lower versus historical control
SER-155 Pharmacodynamics (pathogen domination): prevalence in SER-155 Cohort 2 was substantially lower relative to Historical Control Cohort Pathogen domination (i.e., relative abundance in the GI ≥30%) has been associated with risk of BSIs and other negative clinical outcomes1, 2 Observed pathogen
Slide 23: Epithelial barrier exploratory biomarker results
Clinical: Epithelial barrier exploratory translational biomarker results support intended mechanisms of action and clinical safety and efficacy results Box plots (SER-155 = blue; Placebo = grey; Healthy Control = green) represent the 25th and 75th percentiles of the inter-quartile range (IQR) of dis
Slide 24: Anti-inflammatory translational biomarker results
Clinical: Anti-inflammatory translational biomarker results support intended mechanisms of action and clinical safety and efficacy results "155 < PBO" indicates time points with lower biomarker concentrations in SER-155 arm compared to placebo. Blue shaded cells indicate time points with statistical
Slide 25: US HCPs seek significant reduction of infection risk without compromising safety
US HCPs seek significant reduction of infection risk without compromising patient safety and would incorporate such a therapeutic into standard of care Efficacy Safety Health economics Reduce incidence of bloodstream infections: target 20% BSI rate vs. current 40% rate Reduce systemic antibiotic use
Slide 26: US HCPs see SER-155 as potentially transformative
US HCPs see SER-155 as a potentially transformative means to eliminate complications that get in the way of achieving transplant success Primary Value Driver for SER-155 Reducing the risk of HSCT-related complications, thus ensuring successful engraftment and long-term health of the patient A relati
Slide 27: US payers confirm high unmet need for infection prophylaxis in allo-HSCT
US payers confirm high unmet clinical need for infection prophylaxis in allo-HSCT recipients and robust profile of SER-155 High clinical burden and unmet need High perceived clinical burden of BSIs within the allo-HSCT patient population is driven by high frequency of occurrences and poor associated
Slide 28: EU KOLs supportive of SER-155 Phase 1b results
EU KOLs supportive of SER-155 Phase 1b results; eager to participate in Phase 2 clinical trial AML: acute myelogenous leukemia. BSI: Blood stream infections. HCT: hematopoietic cell transplantation. MDRO: multi-drug resistant organism. PTCy: post-transplant cyclophosphamide Ω EU KOL feedback on SER-
Slide 29: Viral prophylaxis provides precedent in medically vulnerable patients
Viral prophylaxis provides precedent in medically vulnerable patients Prevymis - increasingly used for viral infection prophylaxis (e.g., allo-HSCT and solid organ transplant populations) $785M ‘24 WW sales (~30% growth over '23) Reduces CMV infection in allo-HSCT recipients Lowers mortality rate Ov
Slide 30: SER-155 has blockbuster commercial potential
SER-155 has blockbuster commercial potential, driven by a robust SER-155 profile and substantial unmet needs in allo-HSCT and additional groups Sources: CIBMTR; HRSA; Passweg et al, BMT 2021; IQVIA; Broder et al, Am Drug Health Benefits 2017; Perales et al, Biol Blood Marrow Transplant 2017 CMS.gov;
Slide 31: Representative indication expansion: potential 10x addressable population
Representative indication expansion: potential 10x addressable population US annual diagnoses or transplants Unmet needs addressed by SER-155 Allo-HSCT ~9,300 Prevent mortality and cost of post-transaction infections Autologous HSCT ~13,500 Prevent mortality and costs of post-transplant infections B
Slide 32: Accelerating SER-155 clinical development based on positive Phase 1b outcomes
Accelerating SER-155 clinical development based on positive Phase 1b outcomes Efforts are ongoing to seek capital and other resources to support SER-155 Phase 2 study Constructive engagement with FDA on advancement of SER-155 allo-HSCT program Received Breakthrough Therapy designation in December 20
Slide 33: SER-147 developed to prevent infections in chronic liver disease patients
SER-147 developed to prevent infections in chronic liver disease patients Substantial unmet need Promising preclinical data Sources: GBD 2017 Cirrhosis Collaborators, Lancet Gastroenterology & Hepatology 2020; United Nations world population data; Trebicka et al, J Hepatol 2020; Seres preclinical da
Slide 34: SER-603 designed to target inflammatory drivers of IBD
SER-603 designed to target inflammatory drivers of Inflammatory Bowel Disease (IBD) that current standards of care cannot Seres Therapeutics, Inc. © 2025 IBD is a mucosal barrier-immune disease Seres IBD Program Sources: Seres data on file Inflammatory microbiome Overabundance of pathogenic and infl
Slide 35: Manufacturing platform delivers defined consortia in oral formulation
Manufacturing platform delivers defined consortia in oral formulation using cost-effective production Novel formulations enabling consistent drug product composition, drug stability for distribution, and targeted drug delivery Quality systems to ensure product quality and stability, extending prior
Slide 36: Maximizing opportunity of live biotherapeutics going forward
Maximizing opportunity of live biotherapeutics going forward SER-155 Bloodstream infections in Allo-HSCT: Finalizing SER-155 Phase 2 study protocol based on FDA feedback and supported by Breakthrough Therapy designation Evaluate in additional cancer treatment populations w/ high risk of serious bact
Slide 37: Summary and path forward
Summary and path forward SER-155 Phase 1b placebo-controlled results promising, Phase 2 planning ongoing Finalizing SER-155 Phase 2 study protocol based on constructive FDA engagement; Commencement of study is funding dependent Administration associated with 77% relative risk reduction for BSIs, sig
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