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RecruitingNCT06871111MARCOUpdated Nov 4, 2025

The Microbiota Augmentation to Reestablish Commensal Organisms (MARCO) Trial

A Phase 1 interventional study of Commensal Bacteria Strains in Liver Diseases, Liver Failure and Cirrhosis, Liver, sponsored by University of Chicago. Recruiting at 1 site in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2025-11-04.

Sponsored by University of Chicago · Phase 1, Interventional, and Treatment

From the registry’s dates

  • Started Aug 2025; still recruiting 1 year 3 months later.
Phase
Phase 1
Study type
Interventional
Enrollment
24
Allocation
Non-randomized
Ages
18 Years and older
Sex
All
01

Study summary

The Microbiota Augmentation to Reestablish Commensal Organisms (MARCO) trial is a single center prospective adaptive phase 1b clinical trial in patients who are hospitalized with complications of liver disease and have low fecal metabolite levels (butyrate and deoxycholic acid). The study intervention is 1 of 9 novel live Commensal Consortia each containing eight commensal bacterial strains derived from healthy donors. The primary objective of the study is to determine safety and tolerability of Commensal Consortia administration.

Read the detailed description

The global burden of chronic liver disease (CLD) continues to rise. CLD is often clinically silent until an initial decompensation event, after which care is largely supportive without the ability to significantly modify the underlying disease with current therapies. Due to the high rates of infection in patients with liver disease, empiric, broad spectrum antibiotics are commonly prescribed. This practice is associated with altered gut microbiome compositions, reduced levels of health-promoting bacterial metabolites and high levels of antibiotic resistant organisms, findings that correlate with poor clinical outcomes including infection, repeat hepatic decompensation, re-hospitalization and death.

The primary objective of this clinical trial is to test the safety of commensal bacterial strain combinations designed to reconstitute microbiota compositions and metabolite production in patients with liver disease and profound dysbiosis as measured by low fecal metabolite (butyrate and deoxycholic acid) concentrations. The exploratory outcomes include strain engraftment and bacterial metabolite production.

The trial will occur in two phases. During the first phase, 8 patients will be recruited and administered the same combination of bacterial strains for 7 doses. Patients will be monitored for safety and tolerability. Additionally, fecal samples will be collected to assess for the presence of administered strains and fecal metabolite production.

After the first phase, additional combinations of bacteria will be chosen based upon the safety, engraftment and metabolite production in the first phase. In this adaptive phase, an additional 16 subjects will be enrolled and randomized to one of two additional consortia. In the two phases, a total of 24 patients will be enrolled, and each will be followed for 12 months to assess both primary (safety and tolerability) and exploratory (engraftment and metabolite production) outcomes. The investigators anticipate completing enrollment within 12 months of trial initiation.

02

Conditions studied

  • Liver Diseases
  • Liver Failure
  • Cirrhosis, Liver
03

In context

Liver Diseases

824 studies on the registry are indexed under Liver Diseases; 152 are open to participants now.

This study's planned enrollment of 24 is below the median of 52 across 521 interventional studies indexed under Liver Diseases.

Browse Liver Diseases studies →

Lead sponsor

University of Chicago is the lead sponsor of 924 studies on the registry; 185 are open to participants now.

Of its 103 completed or terminated interventional studies of FDA-regulated products, 72 (70%) have results posted.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
Accepts healthy volunteers
No

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.

Inclusion criteria

  • Age 18 years or older
  • Diagnosis of liver disease, liver failure, and/or cirrhosis
  • All patients will be hospitalized and have a hepatology consult in place.
  • They will be identified as having liver disease, liver failure, and/or cirrhosis based on a combination of at least one of the following:

    • Labs demonstrating elevated liver chemistries ( and ALT), elevated serum levels, prolonged , or radiologic evidence of cirrhosis (e.g. nodular liver contour);
    • Liver results; and/or
    • Clinical or radiologic evidence of portal hypertension (e.g. splenomegaly, known varices, ascites, or hepatic venous pressure gradient ≥ 10mmHg).
    • All diagnoses will be confirmed by the attending hepatologist's interpretation and consult note attestation.
  • Admitted to the hospital for hepatic decompensation
  • MELD score ≤ 30 at time of enrollment
  • Subject has ≤ 700µM butyrate and ≤ 10µM deoxycholate in fecal sample

Exclusion criteria

Exclusion Criteria:

  • MELD score >30 at time of enrollment
  • Patients receiving any antibiotics for treatment of an infection.
  • Chronic or prophylactic antibiotic administration other than rifaximin, ciprofloxacin, or trimethoprim-sulfamethoxazole.

    -Rifaximin will be either temporarily held or switched to another non-antibiotic therapy (e.g. lactulose or sodium benzoate) during the treatment phase of the trial. Potential subjects in whom the treating hepatologist deem it unsafe to pause or switch from Rifaximin therapy during the 7-10 day treatment phase will be excluded from the study.

  • Patients who are currently admitted to the intensive care unit for vasoactive support or mechanical ventilation.
  • Patients meeting the North American Consortia for Study of End Stage Liver Disease (NACSELD) criteria for acute-on-chronic liver failure (ACLF) with ≥ 2 organ failures by NACSELD-ACLF criteria at time of enrollment.
  • Patients with known intestinal barrier dysfunction, including active GI bleeding, enteropathy (including celiac disease), clinically active inflammatory bowel disease (Crohn's or Ulcerative Colitis), ischemic colitis, microscopic colitis, (GVHD), or gastrointestinal .

    o Active inflammatory bowel disease (IBD) will be defined based on a combination of:

    • Symptoms (diarrhea and/or abdominal pain without another explanation)
    • Laboratory evidence of inflammation (e.g. elevated CRP or fecal calprotectin without another explanation); and
    • Either radiologic, endoscopic, and/or histologic evidence of active IBD.
    • If IBD is suspected, this will be investigated with the general GI consult service prior to approaching for enrollment.
    • If patients carry a diagnosis of IBD but do not meet the above criteria, they will be eligible for enrollment unless their IBD is managed with a systemic medication (e.g. anti-TNF-alpha therapy).
    • If any form of the above intestinal disorders is suspected, they will be investigated with the general GI consult service prior to approaching for enrollment.
  • Profoundly immunocompromised patients, including patients with primary immunodeficiency, solid organ transplant recipients, any history of hematopoietic stem cell transplant (), ongoing cancer treatment, neutropenia \< 500 cells/mm3, untreated or with CD4 \< 200 cells/mm3, immunosuppressive medications, including rituximab, anti-cytokine therapy, anti-rejection medications, chronic (a dose ≥ 20mg of prednisone daily for ≥ 1 month), biologic therapy for condition.
  • Patients with delayed gastrointestinal motility as evidenced by ≤ 2 bowel movements per week at the time of enrollment.
  • Patients who are allergic to both ampicillin/sulbactam and meropenem.

    • These are the two empiric antibiotic therapies that every strain is susceptible to.
    • If a patient is allergic to only one of these medications, they may still be approached for enrollment.
  • A history of allergy to any of the products/components.
  • Patients with liver disease from .
  • Patients with existing inflammatory arthritis.
  • History of total colectomy.
  • Patients who do not intend to continue their care on a routine basis at the University of Chicago beyond 6 months from the time of enrollment.
  • Patients with untreated psychiatric conditions, including illicit substance use disorders, that may interfere with reliable follow-up.
  • Unable to participate based on medical judgement of the care team.
  • Special populations:

    • Women of childbearing age will have a:

      • Negative serum pregnancy test at screening
      • Use a medically acceptable and highly effective method of for at least 6 weeks following completion of treatment.
    • Another investigational drug or LBP:

      • Prior use will be permitted;
      • Concurrent use will preclude enrollment;
      • Use will be restricted for the duration of the study (12 months after commensal consortia completion)
    • Patients who are prescribed ACE-inhibitors and receive a consortium containing C. comes will receive more frequent blood pressure monitoring.
    • Patients who are prescribed metformin will require either:

      • Switch to another medication for diabetes control; or
      • More frequent Vitamin B12 monitoring at 1, 3, 6, and 12 months of enrollment.
  • If a Vitamin B12 deficiency is discovered, it will be repleted as clinically indicated.
Terms in these criteria, in plain language(14)

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.

ALT and AST (liver enzymes)

Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.

Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.

Bilirubin

A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.

Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.

INR, PT and aPTT (clotting tests)

Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.

Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.

Biopsy and archival tissue

A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.

Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.

GVHD (graft-versus-host disease)

After a transplant from a donor, the donor’s immune cells attack the recipient’s body, often the skin, gut or liver.

Cancer (malignancy)

Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.

Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.

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.

Allogeneic and autologous transplant

Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.

HIV

The human immunodeficiency virus, which weakens the immune system.

Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.

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.

Autoimmune disease

A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.

Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.

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.

Hepatitis C tests

Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.

After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.

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.

05

Study design

Phase
Phase 1
Primary purpose
Treatment
Allocation
Non-randomized
Intervention model
Sequential assignment
Masking
None (open label)
Enrollment
24 participants (estimated)

Study arms

  • Experimental
    Commensal Consortium A

    Stage 1: 1st 8 patients enrolled will receive Consortium A. This consortium contains 7 different organisms.

    Biological: Commensal Bacteria Strains

  • Experimental
    Commensal Consortium B1

    Stage 2: Based on fecal metagenomic and metabolomic data from Stage 1, subjects may be assigned to this Commensal Consortium. This consortium contains 7 different organisms.

    Biological: Commensal Bacteria Strains

  • Experimental
    Commensal Consortium B2

    Stage 2: Based on fecal metagenomic and metabolomic data from Stage 1, subjects may be assigned to this Commensal Consortium. This consortium contains 7 different organisms.

    Biological: Commensal Bacteria Strains

  • Experimental
    Commensal Consortium C1

    Stage 2: Based on fecal metagenomic and metabolomic data from Stage 1, subjects may be assigned to this Commensal Consortium. This consortium contains 7 different organisms.

    Biological: Commensal Bacteria Strains

  • Experimental
    Commensal Consortium C2

    Stage 2: Based on fecal metagenomic and metabolomic data from Stage 1, subjects may be assigned to this Commensal Consortium. This consortium contains 7 different organisms.

    Biological: Commensal Bacteria Strains

  • Experimental
    Commensal Consortium D1

    Stage 2: Based on fecal metagenomic and metabolomic data from Stage 1, subjects may be assigned to this Commensal Consortium. This consortium contains 7 different organisms.

    Biological: Commensal Bacteria Strains

  • Experimental
    Commensal Consortium D2

    Stage 2: Based on fecal metagenomic and metabolomic data from Stage 1, subjects may be assigned to this Commensal Consortium. This consortium contains 8 different organisms.

    Biological: Commensal Bacteria Strains

  • Experimental
    Commensal Consortium E1

    Stage 2: Based on fecal metagenomic and metabolomic data from Stage 1, subjects may be assigned to this Commensal Consortium. This consortium contains 7 different organisms.

    Biological: Commensal Bacteria Strains

  • Experimental
    Commensal Consortium E2

    Stage 2: Based on fecal metagenomic and metabolomic data from Stage 1, subjects may be assigned to this Commensal Consortium. This consortium contains 7 different organisms.

    Biological: Commensal Bacteria Strains

Interventions

  • BiologicalCommensal Bacteria Strains

    7 doses containing 7 capsules will be administered over 7-10 days

    Also known as: Lyophilized live commensal bacterial strains (Live Biotherapeutic Product), Commensal Consortium

06

What researchers measure

Primary outcomes

  1. The incidence of adverse events (AEs and SAEs) attributable to the Commensal Consortia

    Adverse events will be monitored for 1 year after Commensal Consortium administration using in-person contact, telephone calls and/or Patient-Reported Outcomes

    Time frame: Day 1- Month 12

  2. Patient-Reported Outcomes Measurement Information System (PROMIS) scores after Commensal Consortia administration

    Tolerability will be assessed for 1 year after Commensal Consortium administration through completion of PROMIS surveys. Surveys will be obtained by the investigators using in-person contact, telephone calls and/or Patient-Reported Outcomes.

    Time frame: Day 1- Month 12

Secondary outcomes

  1. The presence of administered bacterial strains in fecal samples

    Stool samples will be collected at regular intervals and subjected to shotgun metagenomic sequencing. Strain engraftment will be defined as detection of the administered strains.

    Time frame: Day 1- Month 12

Other outcomes

  1. Metabolite concentrations in fecal samples

    Concentrations of targeted metabolites will be measured in fecal samples collected at regular intervals after Commensal Consortium administration.

    Time frame: Day 1- Month 12

07

Study locations

1 of 1 sites recruiting
08

References and documents

Individual participant data

Plan to share: No

No publications or documents are linked to this record.

09

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Nov 4, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT06871111
Responsible party
Sponsor
First posted
Mar 11, 2025
Start date
Aug 4, 2025
Primary completion
Aug 4, 2027 (estimated)
Completion
Feb 4, 2028 (estimated)
Last update
Nov 4, 2025

Study contacts

Matthew A Odenwald, MD, PhD
Contact
matthew.odenwald@uchicagomedicine.org
773-702-6331
Christopher Lehmann, MD
Contact
773.834.6015

Oversight

Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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