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scAAV8OTC

Phase 1

Ornithine Transcarbamylase (OTC) Deficiency | Gene therapy | Other |Ultragenyx Pharmaceutical Inc.|Last Updated: Jan 26, 2023

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
CONTROLLEDDMC
Total Trials1
Total Enrollment16
FDA Designations
No designations recorded
Clinical Trials (1)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT02991144Safety and Dose-Finding Study of DTX301 (scAAV8OTC) in Adults With Late-Onset Ornithine Transcarbamylase (OTC) DeficiencyPHASE1 COMPLETED 16Jul 31, 2017Dec 16, 2021Jan 26, 20239 United States, Canada +2
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Study Endpoints
Primary Endpoints
Number of Participants With Adverse Events (AEs), Treatment-Emergent Adverse Events (TEAEs), Serious Adverse Events (SAEs), Deaths, and TEAEs Leading to Discontinuation
AEs Prior to Dosing: From signing the informed consent form (ICF) to first dose of study drug. TEAEs: From first dose of study drug up to End of Study (Week 52).

AE: any untoward medical occurrence regardless of its causal relationship to study product. TEAE: any event not present before exposure to study product or any event already present that worsens in either intensity or frequency after exposure to study product. SAE: any event that results in death; is immediately life-threatening; requires inpatient hospitalization or prolongation of existing hospitalization; results in persistent or significant disability/incapacity; results in a congenital anomaly/birth defect; is an important medical event, according to the investigator. AE intensity was rated as Grade 1 (mild), 2 (moderate), 3 (severe), 4 (life threatening), or 5 (death) according to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE). The relationship or association of the study product in causing or contributing to the AE was characterized as: unrelated; possible; probably; definite.

Secondary Endpoints
Change From Baseline Over Time in Rate of Ureagenesis
Baseline (Day 0), Weeks 6, 12, 20, 24, End of Study (Week 52). AUC was derived based on the following time points: 0.5, 1, 1.5, 2, 3, and 4 hours postdose.
Change From Baseline Over Time in Area Under the Curve From Time Zero to 24 Hours (AUC0-24) of Plasma Ammonia
Baseline (Day 0), Weeks 6, 12, 24, End of Study (Week 52). AUC was derived based on predose (time 0) and approximately 2, 4, 8, 12, 16, 20, 24 hours (±5 minutes) postdose.
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Study Design & Arms
AllocationNON_RANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeTREATMENT
Treatment Arms
ArmTypeDescription
Cohort 1: DTX301 2.0 × 10^12 GC/kgEXPERIMENTALDTX301 (scAAV8OTC) 2.0 × 10\^12 GC/kg will be administered as a single peripheral IV infusion. A reactive corticosteroid taper regimen will be administered to control transient vector-induced hepatic effects. Sodium acetate will be used as a tracer to measure the rate of ureagenesis.
Cohort 2: DTX301 6.0 × 10^12 GC/kgEXPERIMENTALDTX301 (scAAV8OTC) 6.0 × 10\^12 GC/kg will be administered as a single peripheral IV infusion. A reactive corticosteroid taper regimen will be administered to control transient vector-induced hepatic effects. Sodium acetate will be used as a tracer to measure the rate of ureagenesis.
Cohort 3: DTX301 1.0 × 10^13 GC/kgEXPERIMENTALDTX301 (scAAV8OTC) 1.0 × 10\^13 GC/kg will be administered as a single peripheral IV infusion. A reactive corticosteroid taper regimen will be administered to control transient vector-induced hepatic effects. Sodium acetate will be used as a tracer to measure the rate of ureagenesis.
Cohort 4: DTX301 1.0x10^13 GC/kg + Prophylactic CorticosteroidsEXPERIMENTALA prophylactic corticosteroid taper regimen (oral prednisone \[or prednisolone\], 60 mg tapered over 9 weeks) will be administered before dosing with DTX301 (scAAV8OTC) to prevent or minimize transient vector-induced hepatic effects. DTX301 (scAAV8OTC) 1.0x10\^13 GC/kg administered as a single peripheral IV infusion. Sodium acetate will be used as a tracer to measure the rate of ureagenesis.
Interventions
NameTypeDescription
scAAV8OTCGENETICnon-replicating, recombinant scAAV8 encoding human ornithine transcarbamylase (OTC)
Reactive Corticosteroid Taper RegimenDRUGOral prednisone \[or oral prednisolone\] 60 mg/day week 1, 40 mg/day Week 2, 30 mg/day Weeks 3 and 4, tapered by 5 mg/week Week 5 and beyond until liver enzymes return to baseline levels. Corticosteroid treatment will be considered when a participant's alanine aminotransferase (ALT) level exceeded the upper limit of normal (ULN) and the ALT increase was considered by the Investigator to be related to DTX301.
Prophylactic Corticosteroid Taper RegimenDRUGOral prednisone \[or oral prednisolone\] 60 mg/day at least 5 days prior to DTX301 administration, tapered over 9 weeks. A prophylactic corticosteroid taper regimen will be administered to prevent or minimize transient vector-induced hepatic effects.
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Eligibility Criteria
Age Range18 Years — N/A
SexALL
Healthy VolunteersNo
Study Sites9

Key Inclusion Criteria: 1. Males and females ≥18 years of age with documented diagnosis of late onset (defined as first manifestation of signs and symptoms at ≥1 month of age) OTC deficiency, confirmed via enzymatic, biochemical, or molecular testing 2. Documented history of ≥1 symptomatic hyperamm...

Countries:United StatesCanadaSpainUnited Kingdom
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