A Phase 3 interventional study of Metformin hydrochloride (HCl) 500mg tablet and Placebo in Medulloblastoma, Childhood and Cognitive Impairment, sponsored by Donald Mabbott. Recruiting at 20 sites in 2 countries. Open to participants aged 7 Years to 21 Years. Per ClinicalTrials.gov, last updated 2026-09-24.
Sponsored by Donald Mabbott · Phase 3, Interventional, and Supportive care
The efficacy of treatment with metformin for promoting cognitive recovery and brain growth in children/adolescents treated for a brain tumour will be investigated in a multi-site Phase III randomized double-blind placebo-controlled parallel arm superiority trial. Specifically, in children/adolescents aged 7 years to 21 years and 11 months who have completed treatment for a brain tumour, is oral administration of metformin for 16 weeks associated with greater improvement of cognitive function and brain growth compared to placebo administered for 16 weeks?
A critical barrier to improving the quality of life of children/adolescents living with cancer is that our curative therapies, which include a combination of surgery, chemotherapy and radiation, have toxic effects on healthy tissue, resulting in long-term problems. This is evident for children and adolescents who survive brain tumours requiring aggressive therapy: they experience brain injury and cognitive impairment. There are few therapies for restoring cognitive function and promoting brain growth in survivors; however new work in regenerative medicine offers a possible alternative. The drug metformin promotes brain growth in animal models by activating neural stem cells. In a pilot trial with 24 participants, we found that metformin was safe and tolerable for use in children/adolescents treated with cranial radiation for a brain tumour and may improve cognition and promote white matter growth. In this multi-site clinical trial, we will test the efficacy of treatment with metformin for brain repair and cognitive recovery in paediatric medulloblastoma and other brain tumour survivors. If we find that metformin promotes cognitive improvement and brain growth in paediatric survivors of medulloblastoma and other paediatric brain tumours treated with cranial radiation, this may offer a viable therapeutic approach that may improve quality of life of these cancer patients and provide a model for treatment of late effects in other paediatric cancers.
This study is designed to test the efficacy of metformin in a 16-week multi-centre, phase III, double-blind, randomized placebo-controlled superiority trial with two parallel conditions (metformin versus placebo). Participants will be randomly assigned to one of the two treatments where they will either complete a 16-week cycle of metformin or a 16-week cycle of placebo. Participants will be randomized using Research Electronic Data Capture (REDCap) to ensure allocation concealment. The randomization code will not be released until the participant has been recruited, consented and passed screening. Outcome assessments will be conducted at Baseline immediately following the completion of week 16 treatment (Post-Intervention, Week 17), and 24 weeks following completion of the intervention (6 Month Follow-Up, Week 41).
The primary endpoint is cognitive function in children/adolescent survivors of a brain tumour at Post-Intervention (Week 17) compared to Baseline. We hypothesize that 16 weeks of treatment with metformin will be associated with better cognitive outcomes than 16 weeks of treatment with placebo. Cognitive outcomes will be measured using tests of working memory, declarative memory, and processing speed.
The key secondary outcome will be diffusion MRI within the corpus callosum at Post-Intervention (Week 17) compared to Baseline. We hypothesize that 16 weeks of treatment with metformin will be associated with increased white matter growth in the corpus callosum compared to 16 weeks of treatment with placebo. Increased white matter growth will be measured using diffusion MRI metrics.
Exploratory outcomes have been selected to investigate broader metformin-induced changes in the brain and cognition.
Metformin is a well-studied medication with a broad clinical experience in children including polycystic ovarian syndrome, diabetes, and obesity. The youngest age of use is 2 years old. The proposed dose and the schedule of administration of metformin is based on safety and toxicity data obtained from our pilot trial and previous use in paediatric populations. One hundred and twenty (120) English speaking and twenty (20) French speaking participants - aged 7 years to 21 years and 11 months - will be recruited from up to 20 sites across Canada and Australia.
Analysis of covariance (ANCOVA) will be used to examine the effects metformin versus placebo for each outcome in English speaking participants, controlling for Baseline outcome measurements. For French speaking participants, IQ testing will be completed, but not Cognitive testing as French-Canadian translations are not available. By focusing on a disease that requires some of the most aggressive therapy used in modern protocols, and by targeting the patients most vulnerable to the harmful effects of treatment we hope to provide a model of intervention that can then be applied to other cancers and actively promote brain health and cognitive recovery.
317 studies on the registry are indexed under Medulloblastoma; 51 are open to participants now.
This study's planned enrollment of 140 is above the median of 31 across 255 interventional studies indexed under Medulloblastoma.
Browse Medulloblastoma studies →This is the only study on the registry with Donald Mabbott as lead sponsor.
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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.
In order to be eligible to participate in this study, an individual must meet all of the following criteria:
No less than 3 weeks after completion of:
Primary therapy for:
medulloblastoma
OR
ependymoma
OR
craniopharyngioma
OR
germ cell tumours
OR
OR
Meet criteria for normal organ function requirements as described below:
Normal renal function defined as: Estimated (eGFR) > 75ml/min/1.73m²
Normal liver function defined as:
Exclusion Criteria:
Participants who meet any of the following criteria will not be eligible to take part in the trial:
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.
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
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.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
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.
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.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Relapsed and refractory
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests 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.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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.
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.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Oral metformin will be administered approximately 500mg/m2/day for 1 week and increased to 1000mg/m2/day for 15 weeks. Doses will be rounded to increments of half tablets (250mg, 500mg, 750mg and 1000mg).
Drug: Metformin hydrochloride (HCl) 500mg tablet
Oral placebo will be administered approximately 500mg/m2/day for 1 week and increased to 1000mg/m2/day for 15 weeks. Doses will be rounded to increments of half tablets (250mg, 500mg, 750mg and 1000mg).
Drug: Placebo
Metformin HCl 500mg tablets contain 500mg of active pharmaceutical ingredient (API) and are white, round, biconvex, film-coated tablets, with a score line on one face and debossed with "HMR" on the other. Each tablet contains the non-medicinal ingredients magnesium stearate and povidone. Tablet coating is comprised of hydroxypropyl methylcellulose, polyethylene glycol and titanium dioxide.
Also known as: Glucophage
Matching white round tablet containing excipients only. The placebo tablets will match the active drug as closely as possible in terms of appearance.
Also known as: Control
Change from Week 1 (Baseline) Children's Auditory Verbal Learning Test-2 (CAVLT-2)/Rey Auditory Verbal Learning Test (RAVLT) Immediate Recall at Week 17 (Post-Intervention) to Assess Declarative Memory
To examine the effectiveness of 16 weeks of treatment with metformin versus 16 weeks of placebo for improving cognition, as measured by CAVLT-2/RAVLT which is a test of auditory verbal learning and memory.
Time frame: Week 1 (Baseline), Week 17 (Post-Intervention)
Change from Week 1 (Baseline) NIH Toolbox List Sort Working Working Memory Test at Week 17 (Post-Intervention) to Assess Working Memory
To examine the effectiveness of 16 weeks of treatment with metformin versus 16 weeks of placebo for improving cognition, as measured by List Sorting Working Memory Test (LSWMT) in which participants will be required to recall and place in sequence stimuli that are presented visually and verbally.
Time frame: Week 1 (Baseline), Week 17 (Post-Intervention)
Change from Week 1 (Baseline) Cambridge Neuropsychological Test Automated Battery (CANTAB) Mean Reaction Time for Correct Trials across the RVP, RTI, MTS, and DMS Subtests at Week 17 (Post-Intervention) to Assess Processing Speed
To examine the effectiveness of 16 weeks of treatment with metformin versus 16 weeks of placebo for improving cognition, as measured by mean reaction time for correct trials across subtests of the CANTAB: 1. Rapid Visual Information Processing (RVP) 2. Reaction Time (RTI) 3. Match to Sample Visual Search (MTS) 4. Delayed Matching to Sample (DMS) Each subtest provides an outcome measure of response latency, which will be averaged across all correct trials for each subtest to provide an overall measure of processing speed.
Time frame: Week 1 (Baseline), Week 17 (Post-Intervention)
Diffusion Kurtosis Imaging (DKI) to Assess White Matter Growth within the Corpus Callosum
To examine the effectiveness of 16 weeks of treatment with metformin versus 16 weeks of placebo for promoting white matter growth within the corpus callosum as measured by DKI including axonal water fraction (AWF), a metric sensitive to myelin. This secondary outcome measure (MRI scan) was made optional to participants enrolled after April 2024.
Time frame: Week 1 (Baseline), Week 17 (Post-Intervention)
Not enrolling at this site.
Plan to share: No
No publications or documents are linked to this record.
Started Jul 2022 (actual). Primary completion is estimated for Nov 2027, 64 months after the start.
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Studies of the drug tested here: Metformin