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NGN-401

Phase 3

Rett Syndrome | Gene therapy | Other |Neurogene Inc.|Last Updated: Mar 13, 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
CONTROLLEDDMCBiomarker
Total Trials1
Total Enrollment33
FDA Designations
No designations recorded
Clinical Trials (1)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT05898620A Novel, Regulated Gene Therapy (NGN-401) Study for Females With Rett SyndromePHASE3 RECRUITING 33Jun 13, 2023Dec 1, 2029Mar 13, 202616 United States, Australia +1
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Study Endpoints
Primary Endpoints
Efficacy of NGN-401
52 Weeks

Responders will be defined as participants who: * Attain a CGI-I score of ≤ 3 ("minimally improved"); * and gain any one developmental milestone/skill from a list of 28, as captured through standardized video recordings and independently verified by blinded central raters.

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Study Design & Arms
AllocationNON_RANDOMIZED
MaskingSINGLE
ModelSEQUENTIAL
PurposeTREATMENT
Treatment Arms
ArmTypeDescription
Pediatric 1e15 vg dose (fully enrolled)EXPERIMENTALDose Level 1 for ages 4-10 years
Adolescent/Adult 1e15 vg Dose (fully enrolled)EXPERIMENTALDose Level 1 for ages 11 years \& above
Pediatric 3e15 vg dose (discontinued)EXPERIMENTALDose Level 2 for ages 4-10 years (discontinued)
Pivotal CohortEXPERIMENTALDose Level 1 for ages 3 and above
Interventions
NameTypeDescription
NGN-401GENETICNGN-401 is a non-replicating, recombinant AAV9 carrying a full length human MECP2 transgene.
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Eligibility Criteria
Age Range3 Years — N/A
SexFEMALE
Healthy VolunteersNo
Study Sites16

Inclusion Criteria: * Females who are between the ages of ≥4 and ≤10 years for Arms 1 and 2 (Arms closed). Females who are ≥11 years of age or older for Arm 3 (Arm closed). Females who are ≥3 for Arm 4, the pivotal cohort. * Diagnosis of typical Rett syndrome with a documented disease-causing mutat...

Countries:United StatesAustraliaUnited Kingdom
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Recent Changes (Last 90 Days)
LOWMay 26, 2026NCT05898620primaryCompletionDate: changed
LOWMay 24, 2026NCT05898620studyFirstPostDate: changed