Safety and Efficacy of MaaT013 with Vancomycin in Children and Adolescents with Gastrointestinal Acute Graft‑versus‑Host Disease

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What is this study about?

Gastrointestinal Acute Graft-versus-Host Disease is a rare condition that can occur after a stem‑cell transplant when the donor’s immune cells attack the lining of the digestive tract, causing pain, diarrhea and loss of appetite. It is especially serious in children and teenagers who have already tried two other treatments without success.

The study uses an investigational product called MaaT013, which is a preparation of allogeneic faecal microbiota, pooled given as a rectal solution. This means that healthy bacteria taken from several donors are mixed together and introduced into the lower intestine to help restore a normal balance of gut microbes. In addition, participants may receive the antibiotic vancomycin taken by mouth to control any unwanted bacteria while the new microbes settle in.

The purpose of the research is to find out whether MaaT013 can be given safely and is tolerated by pediatric and adolescent participants, and whether it can be administered feasibly in this age group. Participants receive the study medication at scheduled visits and are monitored for side effects, ability to keep the solution in the rectum for the required time, and changes in stress or anxiety. Follow‑up visits continue for up to twelve months, during which physicians check for improvement in gastrointestinal symptoms, the need for additional medicines, and overall health status.

1 enrollment

after you agree to take part, you are officially entered into the study.

the research team records your basic information and confirms that you meet the study criteria.

2 baseline assessments

you undergo a physical examination, vital‑sign measurements (such as blood pressure and heart rate), and laboratory tests.

a stress and anxiety questionnaire is completed to establish a starting point for later comparison.

3 start oral vancomycin

you begin taking vancomycin by mouth at a dose of 500 mg.

the exact timing and frequency are determined by the study protocol and your clinician.

4 first maat013 administration

you receive the study drug maat013 as a rectal solution.

the dose is 150 ml, delivered into the rectum.

you are asked to retain the fluid for at least 30 minutes, with the goal of keeping it for up to 1 hour and 2 hours, as tolerated.

5 short‑term safety monitoring

for the 72 hours following each maat013 administration, you are observed for any adverse events that might be related to the treatment.

any symptoms, new medical problems, or changes in your condition are recorded by the study team.

6 follow‑up visits and efficacy assessments

you attend scheduled visits on day 28, day 56, month 3, month 6, and month 12.

at each visit, the investigators evaluate the response of your gastrointestinal graft‑versus‑host disease and any other organ involvement.

they also record your use of steroids, any new or ongoing adverse events, and repeat laboratory tests.

7 extended safety monitoring

from the day you join the study until month 6, all treatment‑emergent and serious adverse events are recorded.

from month 6 to month 12, only serious adverse events and events of special interest are tracked.

8 final evaluation

at month 12, a comprehensive assessment is performed.

outcomes such as overall survival, progression‑free survival, time to disease progression, and steroid‑free status are documented.

the study concludes for you after this final visit.

Who Can Join the Study?

Age: You must be at least 6 years old but younger than 18 years old when you give consent to join the study.
Informed consent: A parent or legal guardian must sign a written permission form for you to take part.
Birth control: If you are a female who could become pregnant, or a male who is sexually active with a partner who could become pregnant, you must use an acceptable method of birth control during the study. Acceptable methods include a progestogen‑only pill, male or female condoms (with or without spermicide), a diaphragm, cap, or sponge, or double‑barrier methods such as a condom plus a diaphragm.
Pregnancy test: Females who could become pregnant must have a negative urine or blood pregnancy test taken within 72 hours before receiving the first dose of the study medication.
Karnofsky/Lansky performance status of 40 or higher: This is a simple scale that doctors use to rate how well you can carry out daily activities. A score of 40 means you are able to care for yourself with some assistance.
Weight: You must weigh at least 15 kilograms (about 33 pounds).
Allogeneic hematopoietic stem cell transplant (allo‑HSCT): You must have received a stem cell transplant from another donor, regardless of the type of donor, the source of the cells, or the medication used to prevent graft‑versus‑host disease (GvHD) before the transplant.
Acute graft‑versus‑host disease (aGvHD) with gut involvement: You must currently have an episode of aGvHD that affects the gastrointestinal (GI) tract at a moderate to severe level (grade II to IV), according to standard guidelines. It may also involve other organs.
Adequate organ function: Your recent lab results must show:
- Absolute neutrophil count (a measure of a type of white blood cell) greater than 500 per microliter.
- Platelet count (cells that help blood clot) greater than 10,000 per microliter.
Doctors may give growth‑factor medicines or platelet transfusions to help meet these numbers.
Resistance to steroids and ruxolitinib: You must have not responded adequately to high‑dose steroids (strong anti‑inflammatory medicines) or to the drug ruxolitinib. This means that after a certain period of treatment, your disease did not get better, got worse, or you could not tolerate the medication.
Non‑malignant disease review: If your underlying condition is not cancer, a special clinical board at the study site must review and approve your eligibility before you can join.

Who Cannot Join the Study?

Uncontrolled infection: Any ongoing fungal, bacterial, viral, or other infection that is not under control and requires antibiotics, antivirals, or antifungal medicines. Simple urinary‑tract infections or uncomplicated sore throats are allowed if they are already improving with treatment.
Other medical problems: Any other illness, metabolic issue, physical exam finding, or lab test result that the doctor believes makes the study treatment unsafe for you.
Signs of chronic graft‑versus‑host disease: If your symptoms look like a new or overlapping chronic form of graft‑versus‑host disease, you cannot join.
Allergy to vancomycin: Known hypersensitivity (allergic reaction) to the antibiotic vancomycin or any of its inactive ingredients.
Active CMV colitis: Ongoing infection of the colon caused by cytomegalovirus (CMV), a type of virus.
Relapsed or persistent cancer: Cancer that has returned or is still present and requires rapid reduction of immune‑suppressing medicines.
Previous systemic aGvHD treatments: Having received systemic treatments for acute graft‑versus‑host disease other than corticosteroids (CS) or the drug ruxolitinib.
Severe organ problems not related to GvHD: Serious liver disease such as cholestasis (impaired bile flow) or unresolved veno‑occlusive disease (VOD) causing persistent bilirubin abnormalities, except for mild Gilbert syndrome.
Significant heart disease: Includes unstable chest pain (unstable angina), a heart attack within the past 6 months, severe heart failure (New York Heart Association class III or IV), or need for medications that support blood pressure and heart function (vasopressors or inotropes).
Serious lung disease: Requires a breathing machine (mechanical ventilation) or high‑flow oxygen with more than 50% oxygen concentration.
Recent severe gut problems: Evidence within the past 6 months of toxic megacolon (dangerous colon swelling), bowel obstruction, or a hole in the intestine (perforation).
Other conditions interfering with participation: Any condition that, in the investigator’s judgment, would prevent full participation, pose a significant risk, or make study results unclear.
Allergy to study ingredients: Known allergy or intolerance to trehalose or maltodextrin, which are ingredients in the study product.
Breastfeeding: Currently breastfeeding females are excluded.
Previous microbiome product: Having received any prior microbiome transplant product (fecal microbiota transplantation, FMT). Prior use of probiotics is allowed.
Other active clinical trial: Participation in another ongoing interventional study that could affect this trial’s outcomes.
Unlikely to complete study visits: If the investigator believes you are unlikely to attend all required visits, follow‑up appointments, or comply with study procedures.
France‑only criteria: Children who are under legal protection (court‑ordered guardianship), whose parents are not covered by French social security, or who would not have health coverage after turning 18 years old.

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name	City	Country	Status
Centre Hospitalier Universitaire De Lille	Lille	France

Other Sites

Site Name	City	Country
Azienda Ospedaliera Santobono Pausilipon	Naples	Italy
Fondazione IRCCS Policlinico San Matteo	Pavia	Italy
Robert Debre University Hospital	Paris	France
Prinses Maxima Centrum voor Kinderoncologie B.V.	Utrecht	The Netherlands
Centre Hospitalier Universitaire De Nantes	Nantes	France
Centre Hospitalier Universitaire De Rennes	Rennes	France
Ospedale Pediatrico Bambino Gesu’	Rome	Italy
Atdmfre Uuqxw Snmbroyam Lnsoch Dm Bwdehdr	Bologna	Italy
Fnafimtqp Pptz La Ibgzpovyzzcyf Bpfzaxfgc Dig Hsclqxtw Uohdopejunptd Lz Prt	Madrid	Spain
Hponzzpy Vzma ddoezpgu	Barcelona	Spain

Trial status

Country	Status	Recruitment Start
France	Not yet recruiting	01.05.2026
Italy	Not yet recruiting	01.05.2026
Spain	Not yet recruiting	01.05.2026
The Netherlands	Not yet recruiting	01.05.2026

Trial locations

Investigated drugs:

Vancomycin is an oral antibiotic that is given to treat bacterial infections in the gut. In this study it is used as a background medication, meaning all participants receive it as part of their standard care while the new treatment is being tested.

MaaT013 is a therapy that uses a mixture of healthy donor stool, called allogeneic pooled fecal microbiota, delivered into the rectum. The goal of this treatment is to restore a healthy balance of bacteria in the intestines of children and adolescents who have severe gastrointestinal graft‑versus‑host disease and cannot be helped by another drug called ruxolitinib.

Gastrointestinal Acute Graft-versus-Host Disease (GI-aGvHD) – GI-aGvHD is a complication that can occur after a stem cell or bone‑marrow transplant, when donor immune cells recognize the recipient’s gut tissue as foreign. The reaction causes inflammation of the stomach, small intestine, and colon, leading to diarrhea, abdominal cramping, and nausea. Early on, the inflammation may be mild and appear a few weeks after the transplant. As the condition progresses, the gut lining can become more damaged, increasing symptom frequency and possibly causing weight loss or dehydration. The disease is monitored over time to determine whether it improves, remains stable, or worsens.

Trial ID:

2025-524302-15-00

Protocol code:

MPOH14

Trial Phase:

Therapeutic exploratory (Phase II)

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Safety and Efficacy of MaaT013 with Vancomycin in Children and Adolescents with Gastrointestinal Acute Graft‑versus‑Host Disease

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?