Long-term Follow-Up for RGX-121

Study Overview
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Brief Summary
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RGX-121-5101 is the long-term follow-up study to the RGX-121-101 first in human study 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.

Detailed Description
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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 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) or until RGX-121 is commercially available in the participant's country, whichever occurs first. No treatment will be directed 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.

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

Conditions
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Mucopolysaccharidosis II

Intervention / Treatment
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* Other: Long-term Follow-Up


Participation Criteria
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Eligibility Criteria
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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: Patient has not received RGX-121 previously in a separate parent trial.

Ages Eligible for Study
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Minimum Age: 28 Months

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Long-term Follow-Up<br>No intervention. | Other: Long-term Follow-Up<br>* No intervention<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidences of Adverse Events over time. | Safety | 3 years | 
| Incidences of Serious Adverse Events over time | Safety | 3 year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Biomarkers [Time frame: 1 Month, 12 Months, 24 Months, 36 Months] | Change from baseline in Glycosaminoglycan levels (ng/mL) | 3 years | 
| Changes in neurodevelopmental parameters of cognitive function [Time Frame: 1 Month, 12 Months, 24 Months, 36 Months] | Change from baseline in neurodevelopment parameters of cognitive, behavioral and adaptive function as measured by the Bayley Scales of Infant and Toddler Development, 3rd Edition (BSID-III) or Kaufman Assessment Battery for Children, 2nd Edition (KABC-II). | 3 years | 
| Changes in neurodevelopmental parameters of cognitive function [Time Frame: 1 Month, 12 Months, 24 Months, 36 Months] | Change from baseline in neurodevelopment parameters of cognitive, behavioral and adaptive function as measured by the Mullen Scales of Early Learning (MSEL) | 3 years | 
| Changes in neurodevelopmental parameters of adaptive behavior function [Time Frame: 1 Month, 12 Months, 24 Months, 36 Months] | Vineland Adaptive Behavior Scales Second Edition (VABS-II) | 3 years | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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MPS II, Gene Therapy, Hunter