Using SER-155 to treat diarrhea in patients receiving immunotherapy

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

Phase 1 Interventional Memorial Sloan Kettering Cancer Center · NCT06801067

This study is testing if a new medication called SER-155 can help adults with severe diarrhea caused by immunotherapy feel better with fewer side effects.

Quick facts

PhasePhase 1
Study typeInterventional
Enrollment15 (estimated)
Ages18 Years and up
SexAll
SponsorMemorial Sloan Kettering Cancer Center Academic / other
Drugs / interventionsinfliximab, vedolizumab, ustekinumab, chemotherapy, Prednisone
Locations7 sites (Basking Ridge, New Jersey and 6 other locations)
Trial IDNCT06801067 on ClinicalTrials.gov

What this trial studies

This study aims to evaluate the safety and efficacy of SER-155 as a treatment for diarrhea caused by immunotherapy-related enterocolitis. Participants will be adults over 18 who have experienced grade 2-3 diarrhea linked to immune checkpoint inhibitors within the last 180 days. The study will assess whether SER-155 can provide relief with minimal side effects. Eligible patients will receive the oral medication and will be monitored for their response to treatment.

Who should consider this trial

Good fit: Ideal candidates are adults over 18 who have experienced significant diarrhea related to immunotherapy.

Not a fit: Patients with active gastrointestinal infections or those not experiencing diarrhea related to immunotherapy may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could significantly improve the quality of life for patients suffering from diarrhea due to immunotherapy.

How similar studies have performed: While the specific use of SER-155 is novel, similar approaches targeting diarrhea in immunotherapy patients have shown promise in other studies.

Eligibility criteria

Show full inclusion / exclusion criteria
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

Where this trial is running

Basking Ridge, New Jersey and 6 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions DiarrheaEnterocolitisSER-155Memorial Sloan Kettering Cancer Center24-231
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.