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Study Comparing Metformin and Tolvaptan for Adults with Autosomal Dominant Polycystic Kidney Disease (ADPKD)

Verified siteRegistered drugNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying a condition called Autosomal Dominant Polycystic Kidney Disease (ADPKD). This is a genetic disorder that causes numerous cysts to grow in the kidneys, which can lead to kidney failure over time. The study is comparing two treatments: Metformin and Tolvaptan. Metformin is commonly used to treat diabetes, but researchers are exploring its potential benefits for ADPKD. Tolvaptan is a medication specifically used to slow down the progression of kidney disease in ADPKD patients.

The purpose of the study is to determine if taking 1500 mg of Metformin daily for two years is as effective or not inferior to Tolvaptan in slowing down the decline of kidney function in people with ADPKD. Participants in the study will be randomly assigned to receive either Metformin or Tolvaptan. The study will last for two years, during which participants will have regular check-ups to monitor their kidney function and overall health.

Throughout the study, the main focus will be on measuring the change in kidney function, specifically looking at the estimated glomerular filtration rate (eGFR), which is a test used to check how well the kidneys are working. Additionally, the study will assess changes in the size of the kidneys using a CT-scan at 12 and 24 months. This research aims to provide valuable insights into the effectiveness of Metformin compared to Tolvaptan in managing ADPKD.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Randomization

    Upon joining the study, participants are randomly assigned to one of two groups. One group will receive metformin, and the other will receive tolvaptan.

    This process ensures that each participant has an equal chance of being assigned to either treatment group.

  2. Step 2

    Medication administration

    Participants in the metformin group will take 1500 mg per day. This medication is administered orally in tablet form.

    Participants in the tolvaptan group will take the medication in tablet form as well. The specific dosage will be either 15 mg + 45 mg, 30 mg + 60 mg, or 30 mg + 90 mg, depending on the assigned regimen.

    Both medications are taken daily for the duration of the study.

  3. Step 3

    Monitoring and assessments

    Participants will undergo regular monitoring to assess kidney function. This includes measuring the estimated glomerular filtration rate (eGFR), which indicates how well the kidneys are filtering.

    The primary outcome is to evaluate the difference in the annualized slope of eGFR between the two treatment groups.

    Secondary assessments include measuring the percent change in total kidney volume (htTKV) using a CT scan at 12 and 24 months.

  4. Step 4

    Study duration

    The study is conducted over a period of two years.

    Participants will continue their assigned treatment and attend scheduled assessments throughout this time.

  5. Step 5

    Completion

    At the end of the study period, final assessments will be conducted to evaluate the outcomes of the treatments.

    The study aims to determine if metformin is equivalent or not inferior to tolvaptan in reducing the decline of kidney function in participants with Autosomal Dominant Polycystic Kidney Disease (ADPKD).

Who can join the trial?

4 criteria

  • Men and women aged between 18 and 55 years
  • A certain level of kidney function, measured as a mean of **eGFR** (a test that shows how well your kidneys are working) of at least 45 ml/min/1.73 m² in two specific visits
  • A **Genetic Diagnosis** of Type I ADPKD with a specific kind of mutation called a truncating mutation
  • Signed and dated **informed consent**, which means you agree to participate in the study after being told all the important details
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Investigated drugs

  • Metformin

    is a medication commonly used to manage blood sugar levels in people with type 2 diabetes. In this trial, it is being tested to see if it can help slow down the decline of kidney function in patients with Autosomal Dominant Polycystic Kidney Disease (ADPKD).

  • Tolvaptan

    is a medication that helps to slow the growth of kidney cysts and preserve kidney function in patients with ADPKD. It works by blocking a hormone that causes the kidneys to retain water, which can help reduce the size of the cysts.

What is already known about the treatment

  • Metformin

    Metformin is typically administered orally in tablet form. It is a well-established medication primarily used to manage type 2 diabetes by lowering blood sugar levels. In the context of clinical trials, it is being investigated for its potential benefits in treating Autosomal Dominant Polycystic Kidney Disease (ADPKD). Metformin works by decreasing glucose production in the liver and improving insulin sensitivity. It belongs to the pharmacological class of biguanides.

  • Tolvaptan

    Tolvaptan is administered orally in tablet form. It is currently approved for use in treating Autosomal Dominant Polycystic Kidney Disease (ADPKD) to slow the progression of kidney function decline. Tolvaptan acts by blocking vasopressin receptors, which helps reduce cyst growth in the kidneys. It is classified as a vasopressin receptor antagonist.

Investigated diseases

Autosomal Dominant Polycystic Kidney Disease – This is a genetic disorder characterized by the growth of numerous cysts in the kidneys. These cysts are filled with fluid and can lead to an increase in kidney size and a decrease in kidney function over time. As the disease progresses, the cysts can cause the kidneys to become enlarged and may lead to complications such as high blood pressure and kidney stones. The condition is inherited in an autosomal dominant pattern, meaning only one copy of the altered gene is sufficient to cause the disorder. Symptoms often appear in adulthood, and the severity can vary widely among individuals. The disease primarily affects the kidneys, but it can also impact other organs, including the liver and pancreas.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-517864-49-01Protocol codeAIFA-2016-02365060Estimated enrolment150 patientsSponsorUniversity Of Bari Aldo Moro

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