A Study of mRNA-3745 in Adult and Pediatric Participants With Glycogen Storage Disease Type 1a (GSD1a)

December 9, 2025 updated by: ModernaTX, Inc.

A Phase 1/2, Adaptive, Open-label, Single Ascending Dose to Multiple Ascending Dose Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of mRNA-3745 in Participants With Glycogen Storage Disease Type 1a (GSD1a), Followed by an Open-label Extension

The main goal of this trial is to evaluate the safety and tolerability of mRNA-3745 via intravenous (IV) administration in adult and pediatric participants with GSD1a.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The study includes a single ascending dose (SAD) stage and a multiple ascending dose (MAD) stage. Participants enrolled in the MAD stage have the option to continue treatment in an open-label extension (OLE) period that will assess long-term safety and clinical activity of mRNA-3745.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
15

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Canada
    • Alberta
      • Edmonton, Alberta, Canada, T6G 2R7
        • Stollery Children's Hospital University of Alberta
    • Ontario
      • Toronto, Ontario, Canada, M5G 1X8
        • The Hospital for Sick Children
  • France
      • Clamart, France, 92140
        • AP-HP - Hôpital Antoine Béclère
      • Tours, France, 37000
        • CHRU Tours - Hôpital Clocheville
  • Netherlands
      • Groningen, Netherlands, 9713 GZ
        • Universitair Medisch Centrum Groningen
  • Poland
      • Warsaw, Poland, 04-730
        • Instytut Pomnik Centrum Zdrowia Dziecka
  • Spain
      • Madrid, Spain, 28026
        • Hospital Universitario 12 de Octubre
      • Málaga, Spain, 29011
        • Hospital Regional Universitario de Málaga
  • United States
    • Connecticut
      • Farmington, Connecticut, United States, 06030-0001
        • University of Connecticut Health Center
    • Massachusetts
      • Boston, Massachusetts, United States, 02115
        • Boston Children's Hospital
    • North Carolina
      • Durham, North Carolina, United States, 27713
        • Duke University Medical Center
    • Ohio
      • Cincinnati, Ohio, United States, 45229
        • Cincinnati Children's Hospital Medical Center
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19104
        • Children's Hospital of Philadelphia
    • Texas
      • Houston, Texas, United States, 77030
        • Baylor College of Medicine
      • Houston, Texas, United States, 77030-1501
        • The University of Texas Health Science Center at Houston
    • Utah
      • Salt Lake City, Utah, United States, 84132-0001
        • University of Utah

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Child, Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Documented GSD1a with confirmation of biallelic gene encoding glucose-6-phosphatase-α (G6PC) mutations by genetic testing.
  • Absence of hospitalization for hypoglycemia in the 4 weeks prior to Screening

Exclusion Criteria:

  • Solid organ transplant
  • Received gene therapy for GSD1a
  • Presence of liver adenoma >5 centimeters (cm) in size
  • Diagnosis of type 1 or type 2 diabetes mellitus
  • Presence of liver adenoma with growth of >2 cm or >5 newly diagnosed liver adenomas, in the previous 2 years

Note: Additional inclusion/exclusion criteria may apply, per protocol.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Sequential Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: SAD: mRNA-3745
Participants will receive a single intravenous (IV) dose of mRNA-3745 on Day 1 in an inpatient setting. Participants that are/have been enrolled in the study and receive an administration of mRNA-3745 may also enroll in one of the MAD cohorts. The first MAD dose must occur at least 21 days after the SAD dose.
Drug: mRNA-3745
Sterile frozen liquid dispersion for injection
Experimental: MAD: mRNA-3745
Participants will receive multiple IV doses of mRNA-3745 in an inpatient setting. Participants will have the option to continue treatment in the OLE.
Drug: mRNA-3745
Sterile frozen liquid dispersion for injection

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
Number of Participants With Treatment-emergent Adverse Events (TEAEs), Serious Adverse Events (SAEs) and TEAEs Leading to Treatment Discontinuation
Time Frame: Day 1 up to approximately 3.5 years
Day 1 up to approximately 3.5 years

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change From Baseline of Area Under the Effect Curve (AUEC) of Blood Glucose and Lactate During Fasting Challenges
Time Frame: Baseline through up to Week 32
Baseline through up to Week 32
Change From Baseline in Time to Hypoglycemia During Fasting Challenges
Time Frame: Baseline through up to Week 32
Baseline through up to Week 32
Change From Baseline in Maximum Effect (Emax) During Fasting Challenges
Time Frame: Baseline through up to Week 32
Baseline through up to Week 32
Number of Participants Not Experiencing Hypoglycemia During Fasting Challenges
Time Frame: Baseline through up to Week 32
Hypoglycemia is defined as blood glucose <60 milligrams (mg)/deciliter (dL) (3.3 millimoles [mmol]/liter [L]) and/or symptoms of hypoglycemia.
Baseline through up to Week 32
SAD only: Maximum Observed Concentration (Cmax) of Messenger Ribonucleic Acid (mRNA) and Lipid Nanoparticle (LNP)
Time Frame: Pre-infusion, during infusion, at the end of infusion (EOI) and post-infusion on Day 1 up to Week 52
Pre-infusion, during infusion, at the end of infusion (EOI) and post-infusion on Day 1 up to Week 52
SAD only: Area Under the Concentration-Time Curve From Time 0 to the Time of the Last Measurable Concentration (AUC0-t) of mRNA and LNP
Time Frame: Pre-infusion, during infusion, at EOI and post-infusion on Day 1 up to Week 52
Pre-infusion, during infusion, at EOI and post-infusion on Day 1 up to Week 52
Change From Baseline in Metabolic Biomarkers of GSD1a
Time Frame: Baseline through up to approximately 6.5 years
Baseline through up to approximately 6.5 years
MAD only: Maximum Observed Concentration at Steady State (Cmax,ss) of mRNA and LNP
Time Frame: Pre-infusion, during infusion, at the EOI and post-infusion on Day 1 up to Week 52
Pre-infusion, during infusion, at the EOI and post-infusion on Day 1 up to Week 52

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
ModernaTX, Inc.

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 1, 2022

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
November 30, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
November 30, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
October 4, 2021

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 14, 2021

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 27, 2021

Study Record Updates

Last Update Posted (Estimated)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
December 15, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 9, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
December 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • mRNA-3745-P102
  • 2022-502963-39-00 (Registry Identifier: Clinical Trials Information System (CTIS))

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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