Our Programs

Seres’ microbiome therapeutics represent an entirely new class of medicines with promise across a wide range of diseases.

Pre-Clinical
Phase 1
Phase 2
Phase 3
Collaborators

Product overview

SER-109 is an investigational, oral, biologically-derived microbiome therapeutic designed to prevent recurrence of Clostridioides difficile, formerly known as Clostridium difficile, infection (CDI) in adults with recurrent CDI. SER-109 is a consortium of purified bacterial spores of multiple Firmicute species, manufactured by fractionating and purifying targeted bacteria from stool of healthy human donors with further steps to inactivate potential pathogens. The FDA has granted SER-109 Breakthrough Therapy designation and Orphan Drug designation. For information on the prior clinical studies of SER-109, see here.

Mechanism of action

SER-109 is a multifunctional consortium of commensal bacteria based on human clinical insights. It is designed to modulate the following microbiome functions →

Unmet need in C. difficile

C. difficile is one of the most urgent bacterial threats in the United States according to the Centers for Disease Control. It is the leading cause of hospital-acquired infection in the United States and is responsible for the deaths of more than 20,000 Americans each year.

The current standard of care for C. difficile infection is antibiotics. However, antibiotic treatment alone is ineffective against dormant spore forms of C. difficile, which can germinate and grow after antibiotics are completed, leading to a vicious cycle of recurrence. Repeated antibiotic exposure also depletes beneficial bacteria that inhibit C. difficile, increasing the risk of recurrence.

SER-109 is designed to break the cycle of recurrent C. difficile infection by acting on multiple disease-relevant pathways simultaneously to address key facets of the disease.

Status of clinical program

Seres has completed enrollment of a Phase 3 ECOSPOR study assessing the safety and efficacy of SER-109 for the treatment of recurrent C. difficile. Patients may still enroll in an open-label extension of the study.

Learn more about our current clinical trials.

Product overview

SER-287 is an investigational, oral, biologically-derived microbiome therapeutic for the treatment of ulcerative colitis (UC). SER-287 is a consortium of multiple bacterial spores manufactured by fractionating and purifying targeted bacteria from stool of healthy human donors. SER-287 has been granted Fast Track designation and Orphan Drug designation by the FDA. A completed SER-287 Phase 1b clinical study demonstrated a statistically significant difference in the clinical remission rate between patients with active mild-to-moderate ulcerative colitis treated with vancomycin followed by daily SER-287 for 8 weeks compared to the placebo group, and a favorable safety profile.

Mechanism of action

SER-287 is a multifunctional consortium of commensal bacteria based on human clinical insights. It is designed to modulate the following microbiome functions →

Unmet need in UC

Ulcerative colitis (UC) is a serious chronic condition marked by persistent inflammation in the digestive tract which can greatly reduce an individual’s quality of life. Although the pathogenesis of UC remains unclear, changes in the gastrointestinal microbiome and associated metabolites appear to be important. The relationship between the immune system and the gut microbiome also appears to play a role in the disease.

First-line therapies for UC are only modestly effective. Non-responders have limited treatment options because potent immunosuppressive therapies have serious side effects which are hard to justify in patients with mild-to-moderate disease. An unmet need exists for a safer and more efficacious oral therapy.

SER-287 is designed to improve symptoms and reduce colonic inflammation by acting on multiple disease-relevant pathways.

Status of clinical program

Seres is evaluating the safety and efficacy of SER-287 in the Phase 2b ECO-RESET study in patients with active mild-to-moderate ulcerative colitis.

Learn more about our current clinical trials.

Product overview

SER-401 is an investigational, oral, biologically-derived microbiome therapeutic designed to modify microbiome function to improve the effectiveness of checkpoint inhibitor therapy in patients with metastatic melanoma. SER-401 is the lead candidate in our immuno-oncology pipeline. It is a consortium of bacterial spores of multiple species manufactured by fractionating and purifying targeted bacteria from the stool of healthy human donors.

Mechanism of action

SER-401 is a multifunctional consortium of commensal bacteria based on human clinical insights. SER-401 is designed to modulate the following microbiome function, which is associated with metastatic melanoma patients’ responses to immunotherapy →

Unmet need in metastatic melanoma

Cancer treatments that work by turning the immune system against cancer, such as checkpoint inhibitors and other immunotherapies, only provide benefit for an estimated 20-30% of treated patients. A robust body of evidence indicates that a diverse gut microbiome plays a central role in patients’ response to cancer immunotherapy.

Status of clinical program

Seres is currently evaluating SER-401 in the MCGRAW Phase 1b study in patients with metastatic melanoma, in collaboration with the Parker Institute for Cancer Immunotherapy and MD Anderson Cancer Center.

Learn more about our current clinical trials.

Product overview

SER-301 is an investigational, oral, rationally-designed, fermented microbiome therapeutic for the treatment of mild-to-moderate ulcerative colitis (UC). SER-301 is a consortium of multiple bacterial strains that is manufactured by fermenting each strain individually and then combining to form drug product.

Mechanism of action

SER-301 is a multifunctional consortium of commensal bacteria designed based on clinical insights from our SER-287 Phase 1b study in UC patients. SER-301 is designed to modulate the following microbiome functions →

Unmet need in UC

UC is a serious chronic condition marked by persistent inflammation in the digestive tract which can greatly reduce an individual’s quality of life, and there is no curative treatment. Though genetic factors contribute to a person’s risk for UC, the relationship between the immune system and the gut microbiome also appears to play a role in triggering the disease.

First-line therapies for UC are only modestly effective. Non-responders have limited treatment options because potent immunosuppressive therapies have serious side effects which are hard to justify in patients with mild-to-moderate disease. An unmet need exists for a safer and more efficacious oral therapy.

SER-301 is designed to improve the symptoms of UC and decrease colonic inflammation by simultaneously acting on multiple disease-relevant pathways to address disease.

Status of clinical program

Seres has initiated clinical activities for a Phase 1b study of SER-301 in patients with ulcerative colitis.

Learn more about our current clinical trials.

Product overview

SER-155 is an investigational, oral, rationally-designed, fermented microbiome therapeutic for the prevention of antibiotic-resistant bacterial infections and graft-versus-host disease (GvHD) in patients following solid organ and allogeneic stem cell transplantation. SER-155 is a consortium of multiple bacterial strains that is manufactured by fermenting them individually and then combining to form drug product.

Mechanism of action

SER-155 is a multifunctional consortium of commensal bacteria designed based on human clinical insights. SER-155 is designed to augment the following microbiome functions, which are associated with better survival and lower rates of infection and GvHD in patients undergoing stem cell transplantation →

Unmet need in antibiotic-resistant infections and GvHD

Antibiotic-resistant infections, GvHD and mortality are frequent serious complications of organ or stem cell transplantation. Antibiotics used to treat infections in this patient population are not always effective and can have significant side effects. Current therapies for the prevention of GvHD rely on broad immunosuppression, which increases the risk of infection, and has limited efficacy for a significant proportion of patients.

Status of clinical development

Initiation of clinical development in process.

Scientific literature

Wilcox et al. The Efficacy and Safety of Fecal Microbiota Transplant for Recurrent Clostridium difficile Infection: Current Understanding and Gap Analysis. Open Forum Infectious Diseases, Volume 7, Issue 5, May 2020, ofaa114, doi:10.1093/ofid/ofaa114. 11 April 2020

SER-109

Publications:

McGovern et al. SER-109, an Investigational Microbiome Drug to Reduce Recurrence After Clostridioides Difficile Infection: Lessons Learned From a Phase 2 Trial. Clin Infect Dis. 2020 Apr 7;ciaa387. doi: 10.1093/cid/ciaa387.

Khanna et al. A Novel Microbiome Therapeutic Increases Gut Microbial Diversity and Prevents Recurrent Clostridium Difficile Infection. J Infect Dis. 2016 Jul 15;214(2):173-81. doi: 10.1093/infdis/jiv766.

Conference Talks and Posters:

Inactivation of Vegetative Bacteria During Production of SER-109, a Microbiome-Based Therapeutic for Recurrent Clostridium difficile Infection
ASM Microbe 2016 conference, June 2016

Comparisons of Microbiomes from US and European Populations Suggest that SER-109 may have Clinical Utility in Broad Geographic Locations for the Treatment of Patients with Recurrent Clostridium difficile Infection
26th European Congress of Clinical Microbiology and Infectious Diseases, April 2016

Vancomycin-Resistant Enterococcal (VRE) Titers Diminish Among Patients with Recurrent Clostridium difficile Infection After Administration of SER-109, a Novel Microbiome Agent
IDWeek 2015 conference, October 2015

Engraftment of SER-109 Spores was Rapid and Durable in Patients with Recurrent Clostridium difficile infection
ICCAC 2015 conference, September 2015

SER-262

Conference Talks and Posters:

Design and Evaluation of SER-262: A Fermentation-Derived Microbiome Therapeutic for the Prevention of Recurrence in Patients with Primary Clostridium difficile Infection
ASM Microbe 2016 conference, June 2016

Design & Evaluation of SER-262: A Fermentation-Derived Investigational Microbiome Therapeutic for the Prevention of Recurrence following Primary difficile Infection.
CDF 2019 conference, November 2019

Sartor & Wu. Roles for Intestinal Bacteria, Viruses, and Fungi in Pathogenesis of Inflammatory Bowel Diseases and Therapeutic Approaches. Gastroenterology. 2017 Feb;152(2):327-339.e4. doi: 10.1053/j.gastro.2016.10.012.

Lloyd-Price et al. Multi-omics of the gut microbial ecosystem in inflammatory bowel diseases. Nature. 2019 May;569(7758):655-662. doi: 10.1038/s41586-019-1237-9.

Rubin et al. ACG Clinical Guideline: Ulcerative Colitis in Adults. Am J Gastroenterol. 2019 Mar;114(3):384-413. doi: 10.14309/ajg.0000000000000152.

SER-287

Conference Talks and Posters:

SER-287, an investigational microbiome therapeutic, induces widespread transcriptional changes related to clinical remission in a placebo-controlled, double-blind randomized trial (SERES-101) in patients with active mild-to-moderate ulcerative colitis
Digestive Disease Week, May 2019

Gopalakrisnan et al. Gut Microbiome Modulates Response to anti-PD-1 Immunotherapy in Melanoma Patients. Science. 2018 Jan 5;359(6371):97-103. doi: 10.1126/science.aan4236.

Matson et al. The Commensal Microbiome Is Associated With anti-PD-1 Efficacy in Metastatic Melanoma Patients. Science. 2018 Jan 5;359(6371):104-108. doi: 10.1126/science.aao3290.

Routy et al. Gut Microbiome Influences Efficacy of PD-1-based Immunotherapy Against Epithelial Tumors. 2018 Jan 5;359(6371):91-97. doi: 10.1126/science.aan3706.

SER-401

Publications:

Gopalakrishnan et al. Intervention Strategies for Microbial Therapeutics in Cancer Immunotherapy. IOTECH. 2020 May 20; (awaiting formal publication) doi:10.1016/j.iotech.2020.05.001

Conference Talks and Posters:

Leveraging gut microbiota networks to impact tumor immunotherapy
American Association for Cancer Research conference, May 2019

Leveraging gut microbiota to impact tumor immunotherapy
American Association for Cancer Research Conference, April 2018

Gooley et al. Reduced mortality after allogeneic hematopoietic cell transplantation. N Engl J Med. 2010 Nov 25; 363(22): 2091–2101. doi: 1056/NEJMoa1004383

Gratwohl et al. Hematopoietic Stem Cell Transplantation: A Global Perspective. JAMA 2010 Apr 28;303(16):1617-24. doi: 1001/jama.2010.491

SER-155 / Infection & GvHD

Taur et al. The effects of intestinal tract bacterial diversity on mortality following allogeneic hematopoietic stem cell transplantation. Blood 2014; 124(7):1174-1182. doi: 10.1182/blood-2014-02-554725

Stein-Thoeringer et al. Lactose drives Enterococcus expansion to promote graft-versus-host disease. Science 2019; 366, 1143–1149. doi: 10.1126/science.aax3760

Peled et al. Microbiota as predictor of mortality in allogeneic hematopoietic-cell transplantation. N Engl J Med 2020; 382:822-34. doi: 1056/NEJMoa1900623