Seres Therapeutics, Inc. · NASDAQ:MCRB
Seres Therapeutics — Investor Presentation (November 2026)
46 slides from Seres Therapeutics's investor presentation, Nov 4, 2026
Slide 1: Company Overview
Company Overview Harnessing the therapeutic potential of microbes to advance the treatment of cancer and inflammatory & immune diseases 2026Q3 Exhibit 99.2
Slide 2: Disclaimers
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: Seres has pioneered a new drug modality
Seres has pioneered a new drug modality and accessed the vast functional and therapeutic potential of microbes to treat and prevent disease Achieved two Breakthrough Therapy Designations (VOWST & SER-155) Clinically demonstrated biotherapeutics can target the mucosal epithelial barrier-immune interf
Slide 4: Harnessing the therapeutic potential of microbes with live biotherapeutics
Harnessing the therapeutic potential of microbes with live biotherapeutics Formulated for oral administration; manufactured from master cell banks Consortia of bacteria that are optimized to produce therapeutically active metabolites that target multiple disease-relevant pathways Clinical translatio
Slide 5: Addressing critical, unmet medical needs in oncology and inflammatory & immune diseases
Addressing critical, unmet medical needs in oncology and inflammatory & immune diseases that are linked to disrupted mucosal epithelial barrier and immunity Hematopoietic allogeneic stem cell transplant (allo-HCT) Patients are severely immune compromised with high-risk of bloodstream infections (BSI
Slide 6: SER-155 Allo-HCT: Ph1b 77% relative risk reduction in BSI
SER-155 Allo-HCT: Ph1b demonstrated 77% relative risk reduction in bloodstream infections (BSI) and well-tolerated FDA Breakthrough Therapy Opportunity Prevent bloodstream & antimicrobial resistant (AMR) infections linked to mortality in allo-HCT recipients and other blood cancer patients Infectious
Slide 7: SER-155 irEC: Phase 1b 80% immunosuppressive-free response
SER-155 irEC: Investigator sponsored Phase 1b study demonstrated 80% immunosuppressive-free clinical response and well-tolerated Primary endpoint: Immunosuppressive-free clinical response at Day 15 (open label n=15) 80% 80% of all participants achieved Response (diarrhea decrease by one or more Grad
Slide 8: SER-603 IBD: Improves response in preclinical models
SER-603 IBD: Improves response to IBD drugs in preclinical models and Seres unique translational biomarkers can predict response to advanced biologics SER-603 targets unique upstream mechanisms of action to treat inflammation with potential as mono- or combo-therapy to address efficacy ceiling Expan
Slide 9: Targeting the mucosal epithelial barrier-immune interface
Seres has clinically translated targeting the mucosal epithelial barrier-immune interface Gastrointestinal Mucosal Epithelial Barrier-Immune Interface GI lumen Epithelium Lamina propria Mucosa Disruption leads to translocation of pro-inflammatory molecules and microbes that drive aberrant host immun
Slide 10: Full stack platform capabilities in novel biotherapeutic modality
Seres has full stack platform capabilities & experience in novel biotherapeutic modality that has delivered two Breakthrough Therapies and a drug licensure Seres has built field-leading biological, clinical microbiome, and manufacturing capabilities with proven ability to design, develop, and receiv
Slide 11: Focused strategy to advance novel biotherapeutics
Focused strategy to advance novel biotherapeutics and deliver shareholder value Capital Strategy & Financial position Seres efforts ongoing to seek partnerships and funding to support continued development toward meaningful clinical milestones across pipeline assets Recent balance sheet strengthenin
Slide 12: Pipeline: Seres biotherapeutics target mucosal barrier-immune diseases
Pipeline: Seres biotherapeutics target mucosal epithelial barrier-immune associated inflammatory diseases and infection leveraging years of clinical progress and data Preclinical Ph1 Ph2 Ph3 Enabling Collaborators IND-enabling studies underway; Potential to target upstream disease pathways that curr
Slide 13: SER-155 Allogeneic hematopoietic stem cell transplant
SER-155 Allogeneic hematopoietic stem cell transplant (allo-HCT) --- Prevention epithelial barrier damage and resulting bloodstream infections (BSI) that can lead to mortality Breakthrough Therapy Designation & Phase 2 Ready
Slide 14: Infection is the leading cause of death post-HCT
Infection is the leading cause of death in first 100 days post-HCT, and recent increased use of post-transplant cyclophosphamide (PTCy) for GvHD is increasing bloodstream (BSI) risk by ~2.5-fold Translocation of pathogens are a significant problem in allogeneic hematopoietic cell transplant patients
Slide 15: Unmet need to prevent BSI and AMR infections
A significant unmet need exists to prevent bloodstream (BSI) and antimicrobial resistant (AMR) infections in immunocompromised patients Address conditioning chemotherapy and prophylactic antibiotic use damage to gastrointestinal microbiome and mucosal epithelial barrier that lead to infections Reduc
Slide 16: SER-155 potential to become critical component of care
SER-155 has the potential to become a critical component of care of immunocompromised patients — Prevent infections that lead to medical complications and mortality Top-Line Results Summary: SER-155 prevented bloodstream infections and protected and repaired the mucosal epithelail barrier integrity
Slide 17: BSIs are a leading cause of death post-transplant
Bloodstream infections (BSIs) are a leading cause of death post-transplant and are increasing in incidence with uptake of post-transplant cyclophosphamide (PTCy) BSI risk increasing due to recent adoption of post-transplant cyclophosphamide (PTCy) for GvHD prophylaxis BSI prevalence high despite sta
Slide 18: SER-155 Phase 1b in allo-HCT: Reduction in BSI and healthcare utilization
SER-155 Phase 1b in allo-HCT: Reduction in bloodstream infections, healthcare and antibiotic utilization, with placebo-like safety Significant reduction (p < 0.05) in bloodstream infection (BSI) incidence (HCT Day 0-30) Significant reduction (p ≤ 0.05) in healthcare utilization: days of antibiotics
Slide 19: SER-155 Phase 1b: Clinical translation on mechanisms of action
SER-155 Phase 1b in allo-HCT: Clinical translation on all drug mechanisms of action further support observed efficacy results Rapid protection of gastrointestinal mucosal epithelial barrier integrity Substantial reduction in pathogen domination in the GI microbiome Improved immune homeostasis reflec
Slide 20: SER-155 Safety: Generally well-tolerated
SER-155 Safety: Generally well-tolerated with no treatment-related severe adverse events (SAEs) All but one subject in the placebo arm experienced at least 1 TEAE Most common for SER-155 treated subjects (≥50% and with a delta ≥5% more than placebo): diarrhea (86% vs. 74% placebo), nausea (62% vs. 5
Slide 21: SER-155 BSI Path Forward
SER-155 BSI Path Forward: SER-155 is Phase 2 ready in allo-HCT and design provides opportunity for adjacent indication expansion Expansion: Auto-HCT, CAR-T & Cancer neutropenia Phase 2 Allo-HCT Allo-HCT bloodstream and antimicrobial resistant infections has strong biological adjacencies to auto-HCT,
Slide 22: US annual diagnoses or transplants and unmet needs
US annual diagnoses or transplants Unmet needs addressed by SER-155 Allo-HCT ~9,300 Prevent mortality and cost of post-transplant infections Autologous HCT ~13,500 Prevent mortality and costs of post-transplant infections Cancer Neutropenia / Broader leukemia & lymphoma population* ~87,000 initial f
Slide 23: Infections in allo-HCT are costly; Prevymis precedent
Infections in allo-HCT are costly; Merck viral prophylaxis drug provides precedent on commercial opportunity in medically vulnerable patients Sources: CMS.gov; Broder et al. 2017 Am Drug Health Benefits; Perales et al, 2017 Biol Blood Marrow Transplant; Merck SEC filings Cost of infections in 2015 d
Slide 24: Value capture: concentrated prescriber universe
Value capture: highly concentrated prescriber universe enables lean commercial model Many key centers were Ph1b trial sites; plan to add more for future trials 185 US centers performed an allo-HCT in 2016-2020 ~80% of US transplants in 70 centers Similar concentration in most major European countrie
Slide 25: SER-428 ICU BSI: Liquid oral dosing formulation
SER-428 ICU BSI: Formulation to enable liquid oral dosing to expand prevention of infections in intubated and other patients unable to swallow capsules Liquid oral dosing of SER-428 decolonizes key pathogens that colonize the GI tract and are associated with infections and poor outcomes Expand preve
Slide 26: SER-155 Immune Checkpoint Inhibitor-Related Enterocolitis (irEC)
SER-155 Immune Checkpoint Inhibitor-Related Enterocolitis (irEC) --- An Alternative To Immunosuppression That May Preserve Checkpoint Inhibitor Therapy Recent Topline Investigator Sponsored Study Results
Slide 27: irEC is a serious, frequent complication of checkpoint inhibitor therapy
irEC is a serious, frequent complication of rapidly growing immune checkpoint inhibitor therapy that requires immunosuppressive treatment and often disrupts life-extending cancer treatment What is Immune Checkpoint Inhibitor-Related Enterocolitis (irEC)? Immune Checkpoint inhibitors (ICIs) activate
Slide 28: Unmet need for therapies that prevent or treat irEC
A significant unmet need exists for new therapies that prevent or treat irEC without immunosuppression and that preserve life-extending checkpoint inhibitor therapy Oral treatment that prevents or resolves irEC without systemic immunosuppression and without a negative impact on immune checkpoint inh
Slide 29: SER-155 potential critical component of cancer care
SER-155 has the potential to become a critical component of cancer care — Reduce toxic side effects, preserve anti-tumor immunity, and enable patients to continue ICI therapy Top-Line Results Summary: SER-155 resulted in immunosuppressive-free clinical response with mechanistic biomarker data suppor
Slide 30: MSK trial of SER-155 in irEC
MSK initiated trial to evaluate safety and efficacy of SER-155, an investigational biotherapeutic optimized to specifically target the type of damage caused by ICIs Memorial Sloan Kettering Cancer Center (MSK) Trial Summary -- NCT06801067 Grade 2-3 irEC 15 participants who had not yet received immun
Slide 31: SER-155 efficacy in representative cancer patient population
SER-155 efficacy response occurred in a cancer patient population representative of current clinical practice, spanned multiple ICI and cancer types Multiple cancer types Majority with stage 3-4 Multiple ICI types used on study: PD-1 inhibitors (Keytruda, Opdivo, Zynz), PD-L1 inhibitors (Imfinzi, Ba
Slide 32: irEC is a significant side effect interrupting ICI therapy
Immune checkpoint inhibitor-related enterocolitis (irEC) is a significant side effect which can cause interruption of ICI cancer therapy and use of immunosuppressives Grade 1 Grade 2 Grade 3 Grade 5 Grade 4 Grade Diarrhea Treatment Guidelines Increase of <4 stools/day over baseline irEC increasing s
Slide 33: SER-155 Top Line Efficacy: 80% response at Day 15
SER-155 Top Line Efficacy: 80% of participants achieved immunosuppressive-free response at Day 15, with 33% of participants achieving complete clinical remission Day 15 Immunosuppressive-Free Response (Primary Endpoint; n=15) 80% 80% of all participants achieved Response 33% of all participants achi
Slide 34: At Day 43, responders had same grade or better
At Day 43, patients with a primary endpoint response at Day 15, had same grade or better Response = diarrhea decrease by ≥ 1 Grade; Remission = Grade 0 (no diarrhea) Secondary Endpoint: 5 of 15 participants maintained immunosuppressive-free response (2 in remission at Grade 0; 3 at Grade 1) 7 of 15
Slide 35: SER-155 Safety through Day 43
SER-155 Safety through Day 43: Generally well-tolerated with no treatment-related severe adverse events (SAEs) Majority of participants (73.3%) experienced a TEAE, most mild to moderate Most common: diarrhea (26.7%), though diarrhea is the primary symptom associated with irEC 4 events were assessed
Slide 36: Pharmacology: Biomarkers support barrier repair and reduced inflammation
Pharmacology: Biomarkers support SER-155 repaired mucosal epithelial barrier & reduced GI inflammation consistent with drug’s design & clinical results Participants show high levels of gastrointestinal (GI) inflammation with a subset also showing evidence of epithelial barrier damage prior to treatm
Slide 37: SER-155 irEC Path Forward
SER-155 irEC Path Forward: Planning FDA engagement to discuss clinical development program for prophylaxis of irEC Unmet medical need with strong economics Advancing the irEC Prophylaxis Program Prevention approach addresses unmet medical need and aims to keep patients on immune checkpoint inhibitor
Slide 38: irEC results represent an additional valuable oncology indication
SER-155 irEC study results are clinically meaningful and represent an additional valuable oncology indication Immune checkpoint inhibitors have revolutionized cancer treatment and represent a sizable market (2025 revenues) Well over $50B [KEYTRUDA, OPDIVO, YERVOY, IMFINZI, others] ~15% projected CAG
Slide 39: SER-603 Inflammatory Bowel Disease (IBD)
SER-603 Inflammatory Bowel Disease (IBD) --- Targeting inflammatory drivers of IBD that current standards of care cannot
Slide 40: Key challenges in IBD suggest new solutions are needed
Key challenges in IBD suggest new solutions are needed Efficacy ceiling experienced by many patients due to non-response or poor durability of response (see figure) Safety concerns limit the potential for combining advanced therapies that are immunosuppressive Current therapies don’t directly target
Slide 41: Biomarker Validation: bacterial features predict response to therapy
Biomarker Validation: Identified bacterial features can predict response to therapy in clinical datasets 8% of Seres biomarker (+) patients experience remission, suggesting patients that have an inflammatory microbiome are very unlikely to respond to Ustekinumab, and may be candidates for combinatio
Slide 42: Monotherapy Proof of Concept: SER-603 in preclinical IBD models
Monotherapy Proof of Concept: SER-603 addresses microbiome-driven inflammation in preclinical disease models of IBD Th1 cells Th17 cells SER-603 intervention reduces fecal lipocalin from inflammatory microbiome SER-603 intervention reduces Th1 and Th17 CD4+ T cells * ** Biomarker-based inflammatory
Slide 43: Combination Therapy Proof of Concept: SER-603 with anti-TNFa
Combination Therapy Proof of Concept: SER-603 increases the efficacy of anti-TNF�� therapy in a preclinical model of microbiome-driven inflammation GF IL10-/-mice Biomarker (+) microbiome test article ~4-5 weeks of colonization Evaluate treatment effect of SER-603 in combination with anti-TNF�� to a
Slide 44: SER-603 potential to address inadequate response in IBD
SER-603 holds the potential to address challenge of inadequate response in IBD patients as well as benefit patients earlier Well-tolerated safety profile and oral delivery creates potential for SER-603 to target mild-moderate patients as Monotherapy or add-on to 5-ASA Novel and complementary mechani
Slide 45: Seres continues on successful journey in live biotherapeutics
Seres continues on successful journey to lead on delivering on the therapeutic potential of live biotherapeutics (LBP) 2011 Seres founded by Flagship Pioneering 2015 SER-109 Breakthrough Therapy Designation -- Seres goes public $133M IPO (MCRB) 2023 SER-109 FDA approval and launch* -- 2020 SER-109 p
Slide 46: Thank You
THANK YOU
Seres Therapeutics — Investor Presentation (November 2026) on 6ix