RGX-121 Gene Therapy in Children 5 Years of Age and Over With MPS II (Hunter Syndrome)

Completed · Phase 1/Phase 2

Conditions studied: Mucopolysaccharidosis Type II (MPS II)

In brief

RGX-121 is a gene therapy which is designed to deliver a functional copy of the iduronate-2-sulfatase (IDS) gene to the central nervous system. This study is a phase I/II study to determine whether RGX-121 is safe, well tolerated, and potentially effective in children five years of age and over who have severe MPS II.

Key facts

Study ID

NCT04571970

Run by

REGENXBIO Inc.

People needed

6

Starts

2021-03-11

Expected to finish

2024-05-23

Last updated by the study team

2025-01-28

Who can join

Age: 5 and older, up to 17. Sex: male. Healthy volunteers: not accepted.

You may qualify if…

• Meets any of the following criteria:
• Has a documented diagnosis of MPS II AND a neurocognitive testing score ≤ 1 ½ standard deviation (SD) from the test normative mean (BSID-III: 77 and MSEL Visual Reception: 35), OR
• Has a documented diagnosis of MPS II AND has a decline of ≥ 1 standard deviation on serial neurocognitive testing administered between 3 to 36 months apart (BSID-III Cognitive or MSEL Visual Reception), OR
• Has a relative clinically diagnosed with neuronopathic MPS II who has the same IDS mutation as the participant AND the participant in the opinion of a geneticist has inherited a neuronopathic form of MPS II, OR
• Has documented mutation(s) in IDS that in the opinion of a geneticist is known to result in a neuronopathic phenotype AND in the opinion of a clinician has a neuronopathic form of MPS II

You may not qualify if…

• Has contraindications for intracisternal injection, intracerebroventricular injection, or lumbar puncture
• Has contraindications for immunosuppressive therapy
• Has any neurocognitive deficit not attributable to MPS II or diagnosis of a neuropsychiatric condition
• Has had prior treatment with an AAV-based gene therapy product
• If receiving ELAPRASE® via intrathecal (IT) administration, must agree to discontinue IT idursulfase for the duration of the study
• Has experienced a serious hypersensitivity reaction to intravenous (IV) ELAPRASE®
• Is currently failing to respond to idursulfase (ELAPRASE®) IV due to neutralizing anti-idursulfase antibodies
• Has received any investigational product within 30 days of Day 1 or 5 half-lives before signing of the ICF, whichever is longer
• Has a platelet count <100,000 per microliter (µL), absolute neutrophil count <1.0 × 103/µL, or aminotransferase (ALT) or aspartate aminotransferase (AST) >3 × upper limit of normal (ULN) or total bilirubin >1.5 × ULN at screening unless the participant has a previously known history of Gilbert's syndrome

Where it is running

• University of California San Francisco, Benioff Children's Hospital — Oakland, California, United States
• McGill University Heath Center — Montreal, Quebec, Canada

Full record on ClinicalTrials.gov

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