A Phase 1 interventional study of SER-155 in Diarrhea and Enterocolitis, sponsored by Memorial Sloan Kettering Cancer Center. Recruiting at 7 sites in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-07-28.
Sponsored by Memorial Sloan Kettering Cancer Center · Phase 1, Interventional, and Treatment
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.
877 studies on the registry are indexed under Diarrhea; 76 are open to participants now.
This study's planned enrollment of 15 is below the median of 137 across 738 interventional studies indexed under Diarrhea.
Browse Diarrhea studies →Memorial Sloan Kettering Cancer Center is the lead sponsor of 1,964 studies on the registry; 327 are open to participants now.
Of its 135 completed or terminated interventional studies of FDA-regulated products, 71 (53%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Concurrent treatment with cytotoxic chemotherapy or other tumor-directed agents is permitted.
abdominal pain, bloody or mucoid stools)
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.
It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Absolute neutrophil count (ANC)
The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.
It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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
Also known as: Cultivated Multi-Strain Live Bacterial Therapeutic, Encapsulated
Proportion of participants with treatment-related adverse events of special interest
Proportion of participants with treatment-related adverse events of special interest, i.e. blood stream infection
Time frame: 1 year
Proportion of patients with treatment-related adverse events
Proportion of patients with treatment-related adverse events
Time frame: 1 year
Proportion of patients with immunosuppressive-free clinical response of irEC (immunotherapy-related enterocolitis) at 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
Time frame: Day 15
Proportion of patients with immunosuppressive-free clinical remission of irEC at 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
Time frame: Day 15
Proportion of patients with immunosuppressive-free clinical response of irEC at day 43
Proportion of patients with immunosuppressive-free clinical response of irEC at day 43
Time frame: Day 43
Proportion of patients with immunosuppressive-free clinical remission of irEC at day 43
Proportion of patients with immunosuppressive-free clinical remission of irEC at day 43
Time frame: Day 43
Time to immunosuppressive-free clinical response
Time to immunosuppressive-free clinical response
Time frame: 1 year
Time to immunosuppressive-free clinical remission
Time to immunosuppressive-free clinical remission
Time frame: 1 year
Number of detectable SER-155 strains at day 15
Number of detectable SER-155 strains at day 15
Time frame: Day 15
Number of detectable SER-155 strains at day 43
Number of detectable SER-155 strains at day 43
Time frame: Day 43
Plan to share: Yes — 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.
Started Jan 2025 (actual). Primary completion is estimated for Jan 2027, 24 months after the start.
Of 22 phase 1 interventional studies under Diarrhea, half reached primary completion within 14 months of starting (the median), counting those still running; a quarter within 6 and three quarters within 23. This study's planned 24 months is above that.
How these figures are worked out, and which studies are left out of them.
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