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Gene Therapy

RGX-121 Gene Therapy for Hunter Syndrome

Phase 1 & 2
Waitlist Available
Research Sponsored by REGENXBIO, Inc.
Eligibility Criteria Checklist
Specific guidelines that determine who can or cannot participate in a clinical trial
Must have
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)
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)
Must not have
Has contraindications for immunosuppressive therapy
Is currently failing to respond to idursulfase (ELAPRASE®) IV due to neutralizing anti-idursulfase antibodies
Timeline
Screening 3 weeks
Treatment Varies
Follow Up baseline, week 1, week 2, week 4, week 12, week 24, week 38, week 52, week 64, week 78, week 104
Awards & highlights

Summary

This trial tests RGX-121, a gene therapy designed to help children with severe MPS II by delivering a healthy gene to their brain cells. The goal is to produce an enzyme that can improve brain function. The study will check if this treatment is safe and effective. Brain-targeted hematopoietic stem cell gene therapy provides a promising therapy for MPS II patients.

Who is the study for?
This trial is for children over 5 with severe Hunter Syndrome, showing specific neurocognitive decline. They must have a genetic diagnosis of MPS II and not be responding to standard treatments. Kids can't join if they've had gene therapy before, are allergic to certain enzyme treatments, or have immune system issues that prevent them from taking immunosuppressants.
What is being tested?
The study tests RGX-121 gene therapy aimed at delivering a working IDS gene to the brain. It's in early stages (phase I/II) to see if it's safe and might work for kids with neuronopathic Hunter Syndrome who haven't improved on current therapies.
What are the potential side effects?
Specific side effects aren't listed here, but common risks of gene therapies include immune reactions, potential damage at injection site, and general symptoms like fever or fatigue. Long-term effects are unknown due to the novelty of this treatment.

Eligibility Criteria

Inclusion Criteria

You may be eligible if you check “Yes” for the criteria below
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I have MPS II and my neurocognitive test scores are below average.
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I have MPS II and my brain function tests show a decline over time.

Exclusion Criteria

You may be eligible for the trial if you check “No” for criteria below:
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I cannot take immunosuppressive medications due to health reasons.
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My body is not responding to ELAPRASE® due to certain antibodies.
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I agree to stop my ELAPRASE® treatment via spinal injection for the study.
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I have previously received AAV-based gene therapy.
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I cannot have treatments injected into my spine or brain.
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I have a brain function issue not caused by my MPS II condition.

Timeline

Screening ~ 3 weeks
Treatment ~ Varies
Follow Up ~baseline, week 1, week 2, week 4, week 12, week 24, week 38, week 52, week 64, week 78, week 104
This trial's timeline: 3 weeks for screening, Varies for treatment, and baseline, week 1, week 2, week 4, week 12, week 24, week 38, week 52, week 64, week 78, week 104 for reporting.

Treatment Details

Study Objectives

Study objectives can provide a clearer picture of what you can expect from a treatment.
Secondary study objectives
Biomarkers
Change in neurodevelopmental parameters
Number of participants with treatment-related adverse events and serious adverse events

Trial Design

1Treatment groups
Experimental Treatment
Group I: Single ArmExperimental Treatment1 Intervention
6.5 × 10\^10 GC/g brain mass of RGX-121

Research Highlights

Information in this section is not a recommendation. We encourage patients to speak with their healthcare team when evaluating any treatment decision.
Mechanism Of Action
Side Effect Profile
Prior Approvals
Other Research
Hunter Syndrome treatments primarily focus on replacing or supplementing the deficient enzyme iduronate-2-sulfatase (IDS). Enzyme replacement therapy (ERT) provides synthetic IDS to reduce glycosaminoglycan (GAG) accumulation but is less effective for neurological symptoms due to its inability to cross the blood-brain barrier. Gene therapy, like RGX-121, delivers a functional IDS gene directly to the CNS, potentially addressing both systemic and neurological symptoms by enabling endogenous enzyme production in critical areas, including the brain.
Toxicology Study of Intra-Cisterna Magna Adeno-Associated Virus 9 Expressing Iduronate-2-Sulfatase in Rhesus Macaques.Insights gained from gene therapy in animal models of retGC1 deficiency.

Find a Location

Who is running the clinical trial?

REGENXBIO, Inc.Lead Sponsor
19 Previous Clinical Trials
2,287 Total Patients Enrolled
Regenxbio Inc.Lead Sponsor
19 Previous Clinical Trials
2,287 Total Patients Enrolled
REGENXBIO Inc.Lead Sponsor
24 Previous Clinical Trials
2,544 Total Patients Enrolled

Media Library

RGX-121 (Gene Therapy) Clinical Trial Eligibility Overview. Trial Name: NCT04571970 — Phase 1 & 2
Hunter Syndrome Research Study Groups: Single Arm
Hunter Syndrome Clinical Trial 2023: RGX-121 Highlights & Side Effects. Trial Name: NCT04571970 — Phase 1 & 2
RGX-121 (Gene Therapy) 2023 Treatment Timeline for Medical Study. Trial Name: NCT04571970 — Phase 1 & 2
~1 spots leftby Oct 2025