NCT07236606

RGX-121-3102 Gene Therapy in Participants With MPS II (Hunter Syndrome)

A Phase 3, Open-Label Study to Evaluate the Efficacy, Safety, and Pharmacodynamics of RGX 121 in Pediatric Participants With Neuronopathic MPS II (Hunter Syndrome)

• Status: Suspended
• Phase: Phase 3
• Study type: Interventional
• Enrollment: 2 (estimated)
• Sponsor: REGENXBIO Inc. · Industry
• Sex: Male
• Age: 4 Months – 5 Years
• Healthy volunteers: Not accepted

Summary

RGX-121 is a gene therapy which is intended to deliver a functional copy of the iduronate-2-sulfatase gene (IDS) to the central nervous system. This study is a safety, efficacy, and pharmacodynamic dose ranging study to determine whether RGX-121 is safe, effective and well-tolerated by patients with MPS II (Hunter Syndrome)

Detailed description

MPS II (Hunter Syndrome) is a rare X-linked recessive genetic disease caused by mutations in the iduronate-2-sulfatase gene (IDS). Enzyme replacement therapy (ERT) with recombinant idursulfase (ELAPRASE®) is the only approved product for the treatment of Hunter syndrome; however, ERT as currently administered does not cross the blood brain barrier and is therefore unable to address the unmet need in MPS II patients with central nervous system (CNS) (neurodevelopment and behavior) involvement. RGX-121 is designed to deliver a functional gene to cells in the CNS. Iduronate-2-sulfatase (I2S) may then be secreted by transduced cells, which may then cross-correct non-transduced cells by taking up the functional enzyme. This is a Phase III, open-label, confirmatory study investigating the efficacy, safety, and pharmacodynamics of RGX-121 treatment of patients with neuronopathic mucopolysaccharidosis type II (MPS II) aged ≥ 4 months to less than 5 years. A one time dose of RGX-121 will be studied in 2 male pediatric participants with neuronopathic MPS II, as supplemented in the analysis with 13 participants who were separately analyzed in the pivotal RGX-121-101 Part 2 study.

Conditions

• MPS II
• Hunter Syndrome (MPS II)

Interventions

Type	Name	Description
GENETIC	RGX-121-3102	Recombinant adeno-associated virus serotype 9 \[AAV9\] capsid containing human iduronate-2-sulfatase (hIDS) expression cassette

Timeline

• Start date: 2025-11-25
• Primary completion: 2028-04-30
• Completion: 2031-05-30
• First posted: 2025-11-19
• Last updated: 2026-02-27

Locations

1 site across 1 country: United States

Regulatory

• FDA-regulated drug study