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

NCT04571970 | Completed Phase 1 DMC FDA Drug

• 1 other identifier: RGX-121-1102
• Study Type: interventional
• Target: 6
• Locations: 2 countries
• Sites: 2

Brief Summary

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.

Conditions

Mucopolysaccharidosis Type II (MPS II)

Keywords

MPS II; gene therapy; Hunter

Outcome Measures

Primary Outcomes (1)

• Number of participants with treatment-related adverse events and serious adverse events

  Number of participants with treatment-related adverse events and serious adverse events as assessed by CTCAE (Version 5.0)

  24 Weeks

Secondary Outcomes (6)

• Number of participants with treatment-related adverse events and serious adverse events

  104 Weeks

• Biomarkers

  Baseline, Week 1, Week 2, Week 4, Week 12, Week 24, Week 38, Week 52, Week 64, Week 78, Week 104

• Biomarkers

  Baseline, Week 1, Week 2, Week 4, Week 12, Week 24, Week 38, Week 52, Week 64, Week 78, Week 104

• Change in neurodevelopmental parameters

  Baseline, Week 52, Week 104

• Change in neurodevelopmental parameters

  Baseline, Week 52, Week 104

Study Arms (1)

Single Arm

EXPERIMENTAL

6.5 × 10\^10 GC/g brain mass of RGX-121

Genetic: RGX-121

Interventions

RGX-121 GENETIC

Recombinant adeno-associated virus serotype 9 capsid containing human iduronate-2-sulfatase expression cassette

Single Arm

Eligibility Criteria

• Age: 5 Years - 17 Years
• Healthy Volunteers: No
• Age Groups: Child (0-17)

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

Sponsors & Collaborators

• REGENXBIO Inc.: lead

Study Sites (2)

University of California San Francisco, Benioff Children's Hospital

Oakland, California, 94609, United States

Location

McGill University Heath Center

Montreal, Quebec, H4A 3J1, Canada

Location

MeSH Terms

Conditions

Mucopolysaccharidosis II; Sudden Infant Death

Condition Hierarchy (Ancestors)

X-Linked Intellectual Disability; Intellectual Disability; Neurobehavioral Manifestations; Neurologic Manifestations; Nervous System Diseases; Genetic Diseases, X-Linked; Genetic Diseases, Inborn; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Heredodegenerative Disorders, Nervous System; Mucopolysaccharidoses; Carbohydrate Metabolism, Inborn Errors; Metabolism, Inborn Errors; Lysosomal Storage Diseases; Mucinoses; Connective Tissue Diseases; Skin and Connective Tissue Diseases; Metabolic Diseases; Nutritional and Metabolic Diseases; Death, Sudden; Death; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Infant Death

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Model Details: Single-arm

Study Record Dates

• First Submitted: September 23, 2020
• First Posted: October 1, 2020
• Study Start: March 11, 2021
• Primary Completion: May 9, 2023
• Study Completion: May 23, 2024
• Last Updated: January 28, 2025

Record last verified: 2025-01

Data Sharing

• IPD Sharing: Will not share

Locations

US (1); CA (1)