Long-term Follow-Up for RGX-121

August 17, 2026 updated by: REGENXBIO Inc.

A Long-term Follow-up Study to Evaluate the Safety and Efficacy of RGX-121

RGX-121-5101 is an observational long-term follow-up study to the RGX-121-101 or RGX-121-1102 studies where participants received RGX-121, a gene therapy intended to deliver a functional copy of the iduronate-2-sulfatase gene (IDS) to the central nervous system. This study will evaluate the long-term safety and efficacy of RGX-121.

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

This is a prospective follow-up study to evaluate the long-term safety and efficacy after a single administration of RGX-121. Eligible participants are those who previously have enrolled in clinical study RGX-121-101 or RGX-121-1102 and received a single intracisternal (IC) or intracerebroventricular (ICV) infusion of RGX-121. Enrollment of each participant will occur the same day or after the participant has completed the end of study (EOS) visit or early termination visit (ET) from the previous (parent) study. Participants will be followed in this study cumulatively for up to 5 years after RGX-121 administration (inclusive of the parent study). No treatment will be administered under this observational protocol. The total study duration for each participant may vary depending on when they enroll in the current study following RGX-121 administration in the parent study.

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.
27

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

  • Brazil
      • Porto Alegre, Brazil, 90035-903
        • Hospital de Clínicas de Porto Alegre
  • United States
    • California
      • San Francisco, California, United States, 94158
        • University of California, San Francisco (UCSF)- Benioff Children's Hospital
    • New Jersey
      • New Brunswich, New Jersey, United States, 08901
        • Saint Peter's Healthcare System
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19104
        • The Children's Hospital of Philadelphia (CHOP)

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

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

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Up to 54 subjects who have received RGX-121 in a previous parent study.

Description

Inclusion Criteria:

  • To be eligible, a participant must have previously received RGX-121 in a separate parent trial.
  • Participant or participant's legal guardian(s) is/(are) willing and able to provide written, signed informed consent

Exclusion Criteria:

  • Participant has not received RGX-121 previously in a separate parent trial.

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

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.
Long-term Follow-Up
No intervention.
Other: Long-term Follow-Up
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
Long-term Safety of RGX-121
Time Frame: 5 years inclusive of parent study
To evaluate the safety of RGX-121 serious and adverse events as assessed by Common Terminology Criteria for Adverse Events (CTCAE Version 5.0).
5 years inclusive of parent study

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
Evaluate the long-term effect of RGX-121 on neurodevelopmental parameters of cognitive, motor, behavioral, and adaptive function (Bayley Scales of Infant and Toddler Development, 3rd Edition)
Time Frame: 5 years inclusive of parent study
To evaluate the long-term effect of RGX-121 on neurodevelopmental parameters as measured by the BSID-III. The BSID-III assesses children aged 1 to 42 months across several domains (cognitive, language, and motor domains) to give a holistic view of the participants' development and potential delays.
5 years inclusive of parent study
Evaluate the long-term effect of RGX-121 on neurodevelopmental parameters of cognitive, motor, behavioral, and adaptive function (Kaufman Assessment Battery for Children, 2nd Edition)
Time Frame: 5 years inclusive of parent study
To evaluate the long-term effect of RGX-121 on neurodevelopmental parameters as measured by the KABC-II. The KABC-II is an individually administered measure of the cognitive processing abilities of children and adolescents aged 3 through 18.
5 years inclusive of parent study
Evaluate the long-term effect of RGX-121 on neurodevelopmental parameters of cognitive, motor, behavioral, and adaptive function (Mullen Scales of Early Learning)
Time Frame: 5 years inclusive of parent study
To evaluate the long-term effect of RGX-121 on neurodevelopmental parameters as measured by the MSEL. The MSEL is a standardized developmentally integrated system that assesses language, motor, and perceptual abilities, and measures cognitive ability and motor development.
5 years inclusive of parent study
Evaluate the long-term effect of RGX-121 on neurodevelopmental parameters of cognitive, motor, behavioral, and adaptive function (Vineland Adaptive Behavior Scales, 2nd Edition)
Time Frame: 5 years inclusive of parent study
To evaluate the long-term effects of RGX-121 on neurodevelopmental parameters as measured by the VABS-II. The VABS-II assesses adaptive behavior in individuals from infancy to age 90 years. The VABS-II offers a way to measure personal and social self-sufficiency in real-life situations and to observe how these cognitive abilities impact the autonomy management process when put into practice
5 years inclusive of parent study
Evaluate the long-term impact of RGX-121 on Plasma Biomarkers (I2S)
Time Frame: 5 years inclusive of parent study
To evaluate the long-term impact of RGX-121 on Plasma biomarker Iduronate-2-sulfatase (I2S) through plasma collection for participants not receiving ERT (discontinued or naïve).
5 years inclusive of parent study
Evaluate the long-term impact of RGX-121 on CSF Biomarkers (I2S)
Time Frame: 5 years inclusive of parent study
To evaluate the long-term impact of RGX-121 on CSF Biomarker Iduronate-2-sulfatase (I2S) through lumbar puncture.
5 years inclusive of parent study
Evaluate the long-term impact of RGX-121 on CSF Biomarkers (GAGs)
Time Frame: 5 years inclusive of parent study
To evaluate long-term impact of RGX-121 on CSF Biomarker Glycosaminoglycans (GAGs) through lumbar puncture.
5 years inclusive of parent study
Long-term effect of RGX-121 on Urine Biomarker (GAGs)
Time Frame: 5 years inclusive of parent study
To evaluate the long-term impact of RGX-121 on Urine Biomarker Glycosaminoglycans (GAGs) through urine analysis.
5 years inclusive of parent study

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.
REGENXBIO Inc.

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.
March 14, 2021

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.
October 1, 2028

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.
October 1, 2028

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 15, 2020

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 15, 2020

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 22, 2020

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.
August 19, 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.
August 17, 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.
August 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.
  • RGX-121-5101

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

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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