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Study on the Safety and Effects of mRNA-3745 for Patients with Glycogen Storage Disease Type 1a (GSD1a)

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 rare genetic condition called Glycogen Storage Disease Type 1a (GSD1a). This condition affects how the body processes sugar, leading to low blood sugar levels. The study will test a new treatment called mRNA-3745, which is designed to help manage this disease. The treatment involves a special type of genetic material called mRNA, which is delivered into the body through an injection. This mRNA is intended to help the body produce a specific enzyme that is missing or not working properly in people with GSD1a.

The purpose of the study is to evaluate the safety and tolerability of mRNA-3745 in participants with Glycogen Storage Disease Type 1a. Participants will receive the treatment through an intravenous (IV) injection, which means it will be administered directly into a vein. The study will start with a single dose and may progress to multiple doses, depending on how participants respond. Throughout the study, participants will be closely monitored to see how their bodies react to the treatment and to check for any side effects.

This study is designed to be adaptive, meaning that the researchers may adjust the treatment plan based on the results they observe. Participants will be involved in the study for a period of time, during which they will have regular check-ups and tests to monitor their health and the effects of the treatment. The study aims to provide valuable information about the potential benefits and risks of using mRNA-3745 for treating Glycogen Storage Disease Type 1a.

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

    Initial administration

    The study begins with the administration of mRNA-3745, which is a treatment designed for individuals with glycogen storage disease type 1a (GSD1a).

    This medication is given through an intravenous (IV) route, meaning it is delivered directly into the bloodstream.

  2. Step 2

    Dose escalation

    The trial involves a phase where the dose of mRNA-3745 is gradually increased. This is done to assess how the body tolerates the medication and to determine the appropriate dosage.

    Participants will receive multiple doses over a specified period, with careful monitoring of their response to the treatment.

  3. Step 3

    Monitoring and assessment

    Throughout the trial, participants will undergo regular monitoring to evaluate the safety and effects of the treatment.

    This includes checking vital signs, conducting blood tests, and performing other necessary assessments to ensure the participant's well-being.

  4. Step 4

    Open-label extension

    After the initial phases, participants may continue in an open-label extension. This means they will continue to receive mRNA-3745 and be monitored for a longer period.

    The purpose of this extension is to gather more information about the long-term effects and benefits of the treatment.

  5. Step 5

    Completion and follow-up

    Upon completion of the trial, participants will have a final assessment to evaluate their overall health and the impact of the treatment.

    Follow-up visits may be scheduled to monitor any lasting effects and to ensure the participant's continued health.

Who can join the trial?

10 criteria

  • Must be at least 18 years old at the time of giving consent. For those aged 12 to 17 or 6 to 11, the participant and/or their legal representative must be willing and able to provide consent or assent as required by local rules.
  • The condition called **Glycogen Storage Disease type 1a (GSD1a)** must be stable, meaning no hospital visits for low blood sugar (hypoglycemia) in the 4 weeks before the study starts.
  • The participant (or their legal representative if under the legal age) must be willing and able to follow the study schedule, treatment plan, and other study requirements.
  • Must have a confirmed diagnosis of **GSD1a** through a specific gene test called **G6PC gene sequencing**. This genetic confirmation is needed before receiving the study drug, but other study steps can start based on a clinical diagnosis.
  • Must have a history of at least one low blood sugar event (blood sugar 60 mg/dL or less) with symptoms, not caused by an illness, within the 12 months before the study starts.
  • Levels of certain liver enzymes, **aspartate aminotransferase** and **alanine aminotransferase**, must be less than 2.5 times the normal limit. These tests can be repeated up to 3 times if needed.
  • Must have a certain level of blood cells: **absolute neutrophil count** of at least 1500/mm3, **platelet count** of at least 150,000/mm3, and **hemoglobin** of at least 10 g/dL.
  • If female, must either not be able to have children or, if able, must not be sexually active or use a highly effective birth control method starting 28 days before the first dose and continuing for 52 weeks after the last dose.
  • If female and able to have children, must have a negative pregnancy test at the start of the study and just before the first dose.
  • If male and sexually active with a female partner who can have children, must agree to use a condom from the first day of treatment and for 52 weeks after the last dose. Additionally, the female partner must use a highly effective birth control method during this time.

Who cannot join the trial?

10 criteria

  • Participants with any other serious health condition that could interfere with the study.
  • Individuals who have had a recent infection or illness that could affect the study results.
  • People who are currently taking medications that might interfere with the study treatment.
  • Participants who have a history of allergic reactions to similar treatments.
  • Individuals who are pregnant or breastfeeding.
  • People who have participated in another clinical trial recently.
  • Participants with a history of substance abuse or alcohol dependency.
  • Individuals who have a mental health condition that could affect their ability to participate in the study.
  • People who have a history of non-compliance with medical treatments.
  • Participants who have any condition that the study doctors believe would make it unsafe for them to participate.
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Investigated drugs

mRNA-3745 is an experimental treatment being studied for its potential to help people with glycogen storage disease type 1a (GSD1a). This treatment involves using a special type of genetic material called mRNA, which is designed to produce a specific enzyme that people with GSD1a lack. The mRNA is delivered into the body using a protective coating made of various substances, including SM-716, OL-56, Cholesterol, and DSPC. The goal of this treatment is to see if it is safe and if it can help the body produce the missing enzyme, which may improve the symptoms of GSD1a.

What is already known about the treatment

mRNA-3745 – This medication is administered intravenously and is currently being studied in clinical trials for its safety and effectiveness. It is designed for individuals with glycogen storage disease type 1a (GSD1a), a rare genetic disorder. The medication works by delivering mRNA encoding the human enzyme G6Pase-α S298C, which is encapsulated in lipid nanoparticles to help restore normal enzyme function. It falls under the pharmacological classification of gene therapy, aiming to address the underlying cause of the disease at the molecular level.

Investigated diseases

Glycogen storage disease type 1a (GSD1a) – This is a rare genetic disorder that affects the body's ability to break down glycogen into glucose, leading to an accumulation of glycogen in the liver and kidneys. It is caused by a deficiency of the enzyme glucose-6-phosphatase, which is crucial for glucose production. As a result, individuals with GSD1a often experience low blood sugar levels, especially during fasting. The disease can also lead to an enlarged liver, growth delays, and increased levels of certain fats and uric acid in the blood. Over time, these symptoms can affect overall health and development. Regular monitoring and management of blood sugar levels are essential for individuals with this condition.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase I/IITrial ID2022-502963-39-00Protocol codemRNA-3745-P102Estimated enrolment59 patientsSponsorModerna Therapeutics Inc.

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