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DTX401

Phase 3

Glycogen Storage Disease Type IA | Gene therapy | Metabolic |Ultragenyx Pharmaceutical Inc.|Last Updated: Mar 25, 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
RandomizedDouble-BlindPLACEBO_CONTROLLEDDMCBiomarker
Total Trials1
Total Enrollment49
FDA Designations
No designations recorded
Clinical Trials (1)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT05139316A Study of Adeno-Associated Virus Serotype 8-Mediated Gene Transfer of Glucose-6-Phosphatase in Patients With Glycogen Storage Disease Type Ia (GSDIa)PHASE3 COMPLETED 49Nov 8, 2021Feb 20, 2026Mar 25, 202620 United States, Brazil +7
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Study Endpoints
Primary Endpoints
Percent Change from Baseline to Week 48 in Daily Cornstarch Intake
Baseline, Week 48
Secondary Endpoints
Change from Baseline to Week 48 in Number of Total Daily Doses of Cornstarch in DTX401 Group Compared to Placebo Group
Baseline, Week 48
Change from Baseline to Week 48 in Percentage of Glucose Values in Hypoglycemic Range (<70mg/dL [3.9 mmol/L])
Baseline, Week 48
Patient Global Impression of Change (PGIC) Assessment Score at Week 48
Baseline, Week 48
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Study Design & Arms
AllocationRANDOMIZED
MaskingQUADRUPLE
ModelCROSSOVER
PurposeTREATMENT
Treatment Arms
ArmTypeDescription
DTX401, Then PlaceboEXPERIMENTALParticipants receive single peripheral intravenous (IV) infusion of DTX401 in solution. At week 48 participants receive single peripheral IV infusion of Placebo.
Placebo, Then DTX401PLACEBO_COMPARATORParticipants receive single peripheral IV infusion of Placebo. At week 48 eligible participants receive single peripheral IV infusion of DTX401 solution.
DTX401 (Japan Only)EXPERIMENTALParticipants receive single peripheral intravenous (IV)infusion of DTX401 in solution.
Interventions
NameTypeDescription
DTX401GENETICnonreplicating, recombinant, adeno-associated virus (AAV) serotype 8 (AAV8)
PlaceboOTHERNormal Saline infusion
Oral prednisoloneDRUGParticipants who receive DTX401 solution will receive oral prednisolone
Placebo for oral prednisoloneDRUGParticipants who receive placebo will receive placebo oral prednisolone to maintain the study blind
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Eligibility Criteria
Age Range8 Years — N/A
SexALL
Healthy VolunteersNo
Study Sites20

Key Inclusion Criteria: * Documented GSDIa with confirmation by molecular testing or enzymatic activity on liver biopsy * Currently receiving a therapeutic regimen of cornstarch (or equivalent), following international guidance/recommendations with stable nutrition, glycemic, and clinical status. *...

Countries:United StatesBrazilCanadaDenmarkGermanyItalyJapanNetherlandsSpain
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Recent Changes (Last 90 Days)
MEDIUMMay 21, 2026NCT05139316TRIAL_REMOVED: changed
MEDIUMMay 21, 2026NCT05139316TRIAL_REMOVED: changed