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RGX-121-3102

Phase 3

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

Success Probability
Approval Probability 71%
TA Base Rate26%
Adjusted LOA41%
ML RiskLOW_RISK
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Market & Valuation
rNPV $3.2B
Market Size $9.4B
Revenue Basis $1.6B
Competitors 6
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Trial Design
UNCONTROLLEDDMCBiomarker
Total Trials1
Total Enrollment2
FDA Designations
No designations recorded
Clinical Trials (1)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT07236606RGX-121-3102 Gene Therapy in Participants With MPS II (Hunter Syndrome)PHASE3 ACTIVE NOT_RECRUITING 2Nov 25, 2025May 30, 2031Jun 4, 20261 United States
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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 — 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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Recent Changes (Last 90 Days)
MEDIUMApr 8, 2026NCT07236606TRIAL_REMOVED: changed
MEDIUMApr 8, 2026NCT07236606TRIAL_REMOVED: changed