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RGX-121-3102

Phase 3

MPS II | Gene therapy | Rare Disease |REGENXBIO Inc.|Last Updated: Jun 4, 2026

Success Probability

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Market & Valuation

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Trial Design

UNCONTROLLEDDMC
Total Trials1
Total Enrollment2

FDA Designations

RMATORPHAN_DRUGRARE_PEDIATRIC_DISEASEFAST_TRACKACCELERATED_APPROVALPRIORITY_REVIEW

Clinical trial landscape

RGX-121-3102 · 1 trial · 2 indications

Phase 3 1
NCT07236606RGX-121-3102 Gene Therapy in Participants With MPS II (Hunter Syndrome)MPS II
ACTIVE NOT_RECRUITING2 Analytics
PHASE3ACTIVE NOT_RECRUITING
RGX-121-3102 Gene Therapy in Participants With MPS II (Hunter Syndrome)
MPS IIUnlock trial analytics

Study Endpoints

Primary Endpoints

Efficacy of RGX-121 on Neurodevelopmental Function (as measured by the Bayley Scales of Infant and Toddler Development, 3rd Edition)
Month 24

To evaluate the effect of RGX-121 on the neurodevelopmental function as measured by the Bayley Scales of Infant and Toddler Development, 3rd Edition (BSID-III).

Efficacy of RGX-121 on Neurodevelopmental Function (as measured by Kaufman Assessment Battery for Children, 2nd Edition)
Month 24

To evaluate the effect of RGX-121 on the neurodevelopmental function as measured by the Kaufman Assessment for Children, 2nd edition (KABC-II). The KABC-II is only given if the participant achieved the max ceiling on the BSID-III Cognitive scale at two consecutive administrations.

Long-term Safety of RGX-121
Year 5

To evaluate the safety of RGX-121 for up to five years including serious and adverse events as assessed by Common Terminology Criteria for Adverse Events (CTCAE) (Version 5.0)

Secondary Endpoints

RGX-121 Change in CSF Biomarkers (as measured by D2S6)
Week 16, Week 52, Month 24
RGX-121 Effect on Daily Living Skills
Month 24
RGX-121 Change in Brain Volume
Week 52 and Month 24
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Study Design & Arms

AllocationNA
MaskingNONE
ModelSINGLE_GROUP
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
2.9×1011 GC/g brain mass of RGX 121EXPERIMENTALAAV9.CB7.hIDS

Interventions

NameTypeDescription
RGX-121-3102GENETICRecombinant adeno-associated virus serotype 9 \[AAV9\] capsid containing human iduronate-2-sulfatase (hIDS) expression cassette
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Eligibility Criteria

Age Range4 Months to 5 Years
SexMALE
Healthy VolunteersNo
Study Sites1

Inclusion Criteria: * The participant's legal guardian(s) is (are) willing and able to provide written, signed informed consent after the nature of the study has been explained, and prior to any study-related procedures being performed. * Is a male ≥ 4 months to \< 5 years of age on Day 1. * Has a ...

Countries:United States
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Frequently asked questions about RGX-121-3102

What is RGX-121-3102 used for?

RGX-121-3102 is an investigational gene therapy being developed for the treatment of MPS II, also known as Hunter syndrome. It is designed to address the underlying genetic cause of this rare disease. The therapy is currently in Phase 3 clinical development.

Who is developing RGX-121-3102?

RGX-121-3102 is being developed by REGENXBIO Inc. (NASDAQ: RGNX). The company is conducting a Phase 3 clinical trial to evaluate the therapy in participants with MPS II (Hunter syndrome).

What phase is RGX-121-3102 in?

RGX-121-3102 is in Phase 3 clinical development. It is an investigational gene therapy and has not been approved by the FDA. The therapy has received several FDA designations, including Regenerative Medicine Advanced Therapy (RMAT), Orphan Drug, Rare Pediatric Disease, Fast Track, Accelerated Approval, and Priority Review.

What clinical trials is RGX-121-3102 in?

RGX-121-3102 is being studied in a Phase 3 clinical trial with the identifier NCT07236606. This trial is titled 'RGX-121-3102 Gene Therapy in Participants With MPS II (Hunter Syndrome)' and is currently active but not recruiting. The trial is enrolling male participants aged 4 months and older in the United States.

Is RGX-121-3102 the same as RGX-121?

RGX-121-3102 is a specific formulation or version of the gene therapy being developed by REGENXBIO. The clinical trial identifier NCT07236606 refers to this specific therapy. It is important to note that RGX-121-3102 is distinct from other RGX-121 products, and its development is focused on MPS II.