An observational study in Mucopolysaccharidosis I, sponsored by REGENXBIO Inc.. Enrolling by invitation at 2 sites in 2 countries. Per ClinicalTrials.gov, last updated 2026-04-29.
Sponsored by REGENXBIO Inc. · Observational
RGX-111-5101 is a long-term follow up study that evaluates the long-term safety and efficacy of RGX-111 in participants who have received RGX-111 (a gene therapy intended to deliver a functional copy of the alpha-L-iduronidase gene (IDUA) to the central nervous system) in a separate parent study.
This is a prospective, multicenter, long-term observational, follow-up study to evaluate the long-term safety and efficacy of RGX-111 after a single administration. Eligible participants are those who previously participated in a clinical study where they received a single intracisternal (IC) or intraventricular (IVR; also referred to as intracerebroventricular [ICV]) infusion of RGX-111. Enrollment of each participant in this study should occur on the same day or after the participant has completed the end of study (EOS) visit or early discontinuation visit (EDV) from a previous (parent) clinical study. Participants will be followed for up to five years after RGX-111 administration (inclusive of the parent study). No treatment will be directed under this observational study. The total study duration for each participant may vary depending on when s/he enrolls in the current study following RGX-111 administration in the parent study.
74 studies on the registry are indexed under Mucopolysaccharidosis I; 7 are open to participants now.
This study's planned enrollment of 21 is below the median of 41 across 21 observational studies indexed under Mucopolysaccharidosis I.
Browse Mucopolysaccharidosis I studies →REGENXBIO Inc. is the lead sponsor of 18 studies on the registry; 2 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Received RGX-111 in a separate parent trial.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Subjects who have received RGX-111 in a separate parent study.
Genetic: No Intervention
Observational study
Evaluation of the long-term safety of RGX-111
Incidences of treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs) over time using CTCAE Version 5.0
Time frame: 5 years inclusive of parent study
Long-term impact of RGX-111 on neurodevelopmental parameters of cognitive, behavioral, and adaptive function (WASI-II)
Change from baseline in neurodevelopmental parameters as measured by the Wechsler Abbreviated Scale of Intelligence (WASI-II). The WASI-II assesses intelligence in individuals from ages 6 to 90 years old. The assessment will yield composite scores that estimate verbal comprehension and perceptual reasoning abilities. The age equivalent scores are also provided for each of the subtests.
Time frame: 5 years inclusive of parent study
Long-term impact of RGX-111 on neurodevelopmental parameters of cognitive, behavioral, and adaptive function (WPPSI-IV)
Change from baseline in neurodevelopmental parameters as measured by the Wechsler Preschool and Primary Scale of Intelligence Fourth Edition (WPPSI-IV). The WPPSI-IV measures the cognitive development in young children approximately 30 to 91 months in age. This study utilizes the General Ability Index (GAI) comprised of 4 core subtests depending on the child's age; the subtests include receptive vocabulary, block design, information, and quiet assembly for children 3 to 47 months and block design, information, matrix reasoning and similarities for ages 48 to 91 months. The subtests have different scoring ranges, with higher subtest raw scores indicating completion of more complex items but can be normalized from cross-subtest comparison.
Time frame: 5 years inclusive of parent study
Long-term impact of RGX-111 on neurodevelopmental parameters of cognitive, behavioral, and adaptive function (BSID-III)
Change from baseline in neurodevelopmental parameters as measured by the Bayley Scales of Infant and Toddler Development, Third Edition. The BSID-III assesses children aged 1 to 42 months across several domains to give a holistic view of the child's development and potential delays. Participants will be assessed for the Cognitive, Language and Motor domains of the BSID-III. The domains have different scoring ranges but can be normalized for cross-domain comparisons.
Time frame: 5 years inclusive of parent study
Long-term impact of RGX-111 on neurodevelopmental parameters of cognitive, behavioral, and adaptive function (VABS-III)
Change from baseline adaptive behavior as measured by Vineland Adaptive Behavior Scales Third Edition (VABS-III). The VABS-III assesses adaptive behavior in individuals from infancy to age 90 years. In this study, 4 domains of Communication, Daily Living Skills, Socialization, and Motor Skills will be assessed. The domains have different scoring ranges, with higher subdomain raw scores indicating greater function, but can be normalized for cross-domain comparisons.
Time frame: 5 years inclusive of parent study
Pharmacodynamic Effect of RGX-111 on CSF Biomarkers (HS)
To assess the pharmacodynamic effect of RGX-111 on Heparan Sulfate (HS) levels measures by lumbar puncture.
Time frame: 5 years inclusive of parent study
Pharmacodynamic Effect of RGX-111 on CSF Biomarkers (IDUA)
To assess the pharmacodynamic effect of RGX-111 on α-L-iduronidase (IDUA) levels measures by lumbar puncture.
Time frame: 5 years inclusive of parent study
Pharmacodynamic Effect of RGX-111 on Plasma Biomarkers (HS)
To assess the pharmacodynamic effect of RGX-111 on Heparan Sulfate (HS) levels measures by plasma collection.
Time frame: 5 years inclusive of parent study
Pharmacodynamic Effect of RGX-111 on Plasma Biomarkers (IDUA)
To assess the pharmacodynamic effect of RGX-111 on α-L-iduronidase (IDUA) levels measures by plasma collection.
Time frame: 5 years inclusive of parent study
Pharmacodynamic Effect of RGX-111 on Urine Biomarkers (GAGs)
To assess the pharmacodynamic effect of RGX-111 on glycosaminoglycans (GAGs) levels measured by urine analysis.
Time frame: 5 years inclusive of parent study
Plan to share: No
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REGENXBIO Inc.