A Study of SER-155 to Treat Diarrhea in People on Immunotherapy

July 27, 2026 updated by: Memorial Sloan Kettering Cancer Center

A Single-Arm, Open-Label, Phase 1 Study to Assess Safety and Preliminary Efficacy of Cultivated Multi-Strain Live Bacterial Therapeutic SER-155 for First-Line Treatment of Immunotherapy-Related Enterocolitis

The purpose of this study is to find out whether SER-155 may be a safe first treatment that causes few or mild side effects for people due to irEC.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
15

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • United States
    • New Jersey
      • Basking Ridge, New Jersey, United States, 07920
        • Recruiting
        • Memoral Sloan Kettering at Basking Ridge (Limited Protocol Activities)
        • Contact:
          • David Faleck, MD
          • Phone Number: 212-639-8286
      • Middletown, New Jersey, United States, 07748
        • Recruiting
        • Memorial Sloan Kettering Monmouth (All Protocol Activities)
        • Contact:
          • David Faleck, MD
          • Phone Number: 212-639-8286
      • Montvale, New Jersey, United States, 07645
        • Recruiting
        • Memorial Sloan Kettering Bergen (All Protocol Activities)
        • Contact:
          • David Faleck, MD
          • Phone Number: 212-639-8286
    • New York
      • Commack, New York, United States, 11725
        • Recruiting
        • Memorial Sloan Kettering Suffolk-Commack (Limited protocol activity)
        • Contact:
          • David Faleck, MD
          • Phone Number: 212-639-8286
      • Harrison, New York, United States, 10604
        • Recruiting
        • Memorial Sloan Kettering Westchester (Limited Protocol Activities)
        • Contact:
          • David Faleck, MD
          • Phone Number: 212-639-8286
      • New York, New York, United States, 10065
        • Recruiting
        • Memorial Sloan Kettering Cancer Center (All Protocol Activities)
        • Contact:
          • David Faleck, MD
          • Phone Number: 212-639-8286
      • Rockville Centre, New York, United States, 11553
        • Recruiting
        • Memorial Sloan Kettering Nassau (Limited Protocol Activities)
        • Contact:
          • David Faleck, MD
          • Phone Number: 212-639-8286

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Age > 18 years
  • Receipt of ICI (single-agent or combination) within the 180 days preceding screening.

Concurrent treatment with cytotoxic chemotherapy or other tumor-directed agents is permitted.

  • Grade 2 - 3 diarrhea (i.e., increase of at least 4 bowel movements a day above baseline during the screening window), deemed by the treating provider as likely related to ICI therapy, with or without concomitant symptoms of grade 1 - 2 colitis (e.g.

abdominal pain, bloody or mucoid stools)

  • Able to swallow oral medication
  • Individuals of childbearing potential willing to use a highly effective method of contraception (failure rate of <1% per year when used consistently and correctly) for 30 days after the last dose of SER-155.
  • Willing to provide written informed consent, comply with the protocol, and understand the potential risks and benefits of study enrollment and treatment.

Exclusion Criteria:

  • Active GI infection, including untreated viral, bacterial or fungal cause(s) of diarrhea.
  • Received immunosuppressive therapies for suspected or confirmed irEC, including systemic corticosteroids (either oral or intravenous) and/or infliximab, vedolizumab or ustekinumab
  • Grade 3 colitis symptoms, i.e. severe abdominal pain or peritoneal signs
  • Admitted to the hospital for irEC
  • Prednisone (or steroid equivalent) dose > 10 mg a day for a non-GI irAE at time of screening
  • Pre-existing inflammatory bowel disease (e.g. Crohn's disease or ulcerative colitis) or microscopic colitis
  • Pregnant or lactating women
  • Any condition that requires ongoing prophylactic or therapeutic antibacterial antibiotics
  • Severe neutropenia, as defined by an absolute neutrophil count (ANC) < 500 cells/mm^3, at time of screening
  • Treatment with investigational medications used for diarrhea/colitis treatment and microbiome therapeutics within 30 days prior to enrollment
  • Known allergy or intolerance to oral vancomycin
  • Unable to comply with the protocol requirements
  • Any condition that in the opinion of the investigator may increase the risk of study participation and/or may interfere with the interpretation of study results

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Participants with Immune checkpoint inhibitor-related enterocolitis (irEC)
Participants with grade 2-3 diarrhea from irEC who have not yet received immunosuppressive therapy for irEC
Biological: SER-155
SER-155 (Cultivated Multi-Strain Live Bacterial Therapeutic, Encapsulated) is an experimental designed ecology of 16 unique, human-commensal bacterial strains encapsulated for oral administration and will be provided by Seres as an investigational drug
Other Names:
  • Cultivated Multi-Strain Live Bacterial Therapeutic, Encapsulated

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Proportion of participants with treatment-related adverse events of special interest
Time Frame: 1 year
Proportion of participants with treatment-related adverse events of special interest, i.e. blood stream infection
1 year
Proportion of patients with treatment-related adverse events
Time Frame: 1 year
Proportion of patients with treatment-related adverse events
1 year

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Proportion of patients with immunosuppressive-free clinical response of irEC (immunotherapy-related enterocolitis) at day 15
Time Frame: Day 15
Proportion of patients with immunosuppressive-free clinical response of irEC (immunotherapy-related enterocolitis) at day 15, defined as at least one grade decrease in diarrhea symptoms without the use of immunosuppressive therapy
Day 15
Proportion of patients with immunosuppressive-free clinical remission of irEC at day 15
Time Frame: Day 15
Proportion of patients with immunosuppressive-free clinical remission of irEC at day 15, defined as resolution in diarrhea symptoms (grade 0) without the use of immunosuppressive therapy
Day 15
Proportion of patients with immunosuppressive-free clinical response of irEC at day 43
Time Frame: Day 43
Proportion of patients with immunosuppressive-free clinical response of irEC at day 43
Day 43
Proportion of patients with immunosuppressive-free clinical remission of irEC at day 43
Time Frame: Day 43
Proportion of patients with immunosuppressive-free clinical remission of irEC at day 43
Day 43
Time to immunosuppressive-free clinical response
Time Frame: 1 year
Time to immunosuppressive-free clinical response
1 year
Time to immunosuppressive-free clinical remission
Time Frame: 1 year
Time to immunosuppressive-free clinical remission
1 year
Number of detectable SER-155 strains at day 15
Time Frame: Day 15
Number of detectable SER-155 strains at day 15
Day 15
Number of detectable SER-155 strains at day 43
Time Frame: Day 43
Number of detectable SER-155 strains at day 43
Day 43

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Memorial Sloan Kettering Cancer Center

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: David Faleck, MD, Memorial Sloan Kettering Cancer Center

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 24, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 24, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 24, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
January 24, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 24, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 30, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
July 28, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 27, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 24-231

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Memorial Sloan Kettering Cancer Center supports the international committee of medical journal editors (ICMJE) and the ethical obligation of responsible sharing of data from clinical trials. The protocol summary, a statistical summary, and informed consent form will be made available on clinicaltrials.gov when required as a condition of Federal awards, other agreements supporting the research and/or as otherwise required. Requests for deidentified individual participant data can be made beginning 12 months after publication and for up to 36 months post publication. Deidentified individual participant data reported in the manuscript will be shared under the terms of a Data Use Agreement and may only be used for approved proposals. Requests may be made to: crdatashare@mskcc.org.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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