Study of Long-Term Safety and Efficacy on Gene Therapy in Glycogen Storage Disease Type Ia

March 16, 2026 updated by: Ultragenyx Pharmaceutical Inc

A Long-Term Follow-up Study to Evaluate the Safety and Efficacy of Adeno Associated Virus (AAV) Serotype 8 (AAV8)-Mediated Gene Transfer of Glucose-6-Phosphatase (G6Pase) in Adults With Glycogen Storage Disease Type Ia (GSDIa)

The primary objective of this study is to determine the long-term safety of DTX401 following a single intravenous (IV) dose in adults with GSDIa.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

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

Only participants who received DTX401 in study 401GSDIA01 (NCT03517085) are eligible to participate in study 401GSDIA02. No investigational product will be administered during study 401GSDIA02. Participants will be followed in study 401GSDIA02 for at least 4 years, and up to 6 years after administration of DTX401.

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.
Observational

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.
12

Contacts and Locations

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

Study Locations

  • Canada
    • Quebec
      • Montreal, Quebec, Canada, H4A3J1
        • Montreal Children Hospital, McGill University Health Centre
  • Netherlands
      • Groningen, Netherlands, 9700RB
        • University Medical Center Groningen
  • Spain
    • A Coruna
      • Santiago de Compostela, A Coruna, Spain, 15706
        • Complejo Hospitalario Universitario de Santiago
  • United States
    • Connecticut
      • Farmington, Connecticut, United States, 06030-3213
        • UConn Health
    • Michigan
      • Ann Arbor, Michigan, United States, 48109
        • Michigan Medicine University of Michigan
    • Texas
      • Houston, Texas, United States, 77030
        • University of Texas Health Science Center at Houston

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 (Adult, Older Adult)

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Subjects 18 years of age or older with GSDIa previously enrolled in 401GSDIA01.

Description

Inclusion Criteria:

  1. Received DTX401 in study 401GSDIA01.
  2. Willing and able to provide written informed consent after the nature of the study has been explained, and prior to any research-related procedures being performed.
  3. Willing and able to comply with all scheduled study visits, procedures, and requirements.

Exclusion Criteria:

  1. Planned or current participation in any other interventional clinical study that may confound the safety or efficacy evaluation of DTX401 during this study.
  2. Presence or history of any condition that, in the view of the Investigator, poses a risk to subject safety or places the subject at high risk of poor compliance or not completing the study or that would significantly affect the interpretation of study results.

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

  • Observational Models: Cohort
  • Time Perspectives: Prospective

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
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.
DTX401 Cohort 1
Participants received a single intravenous (IV) dose of 2.0 × 10^12 GC/kg DTX401(pariglasgene brecaparvovec) with a reactive steroid regimen during their participation in study 401GSDIA01 (NCT03517085). No intervention was provided during the 401GSDIA02 long term follow up study.
Other: No intervention
No intervention
DTX401 Cohort 2
Participants received a single IV dose of 6.0 × 10^12 GC/kg DTX401(pariglasgene brecaparvovec) with a reactive steroid regimen during their participation in study 401GSDIA01 (NCT03517085). No intervention was provided during the 401GSDIA02 long term follow up study.
Other: No intervention
No intervention
DTX401 Cohort 3
Participants received a single IV dose of 6.0 × 10^12 GC/kg DTX401(pariglasgene brecaparvovec) with an optimized reactive steroid regimen during their participation in study 401GSDIA01 (NCT03517085). No intervention was provided during the 401GSDIA02 long term follow up study.
Other: No intervention
No intervention
DTX401 Cohort 4
Participants received a single IV dose of 6.0 × 10^12 GC/kg DTX401(pariglasgene brecaparvovec) with a prophylactic steroid regimen during their participation in study 401GSDIA01 (NCT03517085). No intervention was provided during the 401GSDIA02 long term follow up study.
Other: No intervention
No intervention

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
Measure Description
Time Frame
Number of Participants With Treatment Emergent Adverse Events (TEAEs), Serious TEAEs and Discontinuations Due to TEAEs
Time Frame: From Baseline (Week 52 of 401GSDIA01/Visit 1 of 401GSDIA02) Up to Week 329
An adverse event (AE) is defined as any untoward medical occurrence, regardless of its causal relationship to study product. A TEAE is defined as any AE not present prior to the initiation of the drug treatment or any AE already present that worsens in either intensity or frequency following exposure to the drug treatment. A serious TEAE is an AE that meets any of the following criteria in the view of either the Investigator or Ultragenyx: death; life-threatening; inpatient hospitalization or prolongation of existing hospitalization; disability/Incapacity; congenital anomaly/birth defect not present at screening; other important medical events. Severity of events were graded as mild (grade 1), moderate (grade 2), severe (grade 3), life-threatening (grade 4), or death (grade 5). As DTX401 was administered as part of Study 401GSDIA01, all AEs in Study 401GSDIA02 were considered TEAEs.
From Baseline (Week 52 of 401GSDIA01/Visit 1 of 401GSDIA02) Up to Week 329

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 in Time to First Hypoglycemic Event During a Controlled Fasting Challenge Over Time
Time Frame: Baseline (Week 0 of 401GSDIA01), Weeks 52 (Visit 1 of 401GSDIA02), 78, 104, 130, 156, 182, 208, 234, 260, Last Visit (Up to Week 329)
The change from baseline in time (in hours) to first hypoglycemic event (defined as glucose < 54 mg/dL [< 3.0 mmol/L]) during a controlled fasting challenge at the participant's last visit. A positive change from baseline is favorable. Change from baseline is calculated from Baseline (Week 0) of the 401GSDIA01 study.
Baseline (Week 0 of 401GSDIA01), Weeks 52 (Visit 1 of 401GSDIA02), 78, 104, 130, 156, 182, 208, 234, 260, Last Visit (Up to Week 329)

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.
Ultragenyx Pharmaceutical Inc

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Medical Director, Ultragenyx Pharmaceutical 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.

Helpful Links

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.
July 15, 2019

Primary Completion (Actual)

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.
February 25, 2025

Study Completion (Actual)

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.
February 25, 2025

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).
May 29, 2019

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.
May 29, 2019

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.
May 31, 2019

Study Record Updates

Last Update Posted (Actual)

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.
March 18, 2026

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.
March 16, 2026

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.
March 1, 2026

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.
  • 401GSDIA02
  • 2018-004473-27 (EudraCT Number)
  • 2023-504004-29-00 (Ctis)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Due to the rarity of GSDIa and the small number of subjects in this trial, individual patient data will not be shared in order to safeguard patient privacy, consistent with the data sharing commitment statement listed on Ultragenyx.com.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

product manufactured in and exported from the U.S.

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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