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Clinical Study of DTX301 AAV-Mediated Gene Transfer for Ornithine Transcarbamylase (OTC) Deficiency | Clinical Trials | Clareo Health

ACTIVE_NOT_RECRUITINGPHASE3

Clinical Study of DTX301 AAV-Mediated Gene Transfer for Ornithine Transcarbamylase (OTC) Deficiency

A Phase 3, Randomized, Double-blind, Placebo-controlled Study of Adeno-associated Virus (AAV) Serotype 8 (AAV8)-Mediated Gene Transfer of Human Ornithine Transcarbamylase (OTC) in Patients With Late-onset OTC Deficiency

NCT05345171•Ultragenyx Pharmaceutical Inc

View on ClinicalTrials.gov

Summary

The primary objective is to evaluate the efficacy of DTX301 on the improvement of ornithine transcarbamylase (OTC) function by maintaining safe plasma ammonia levels.

Detailed Description

This study is a Phase 3, randomized, double-blind, placebo-controlled study of DTX301 in patients with late-onset OTC deficiency 12 years of age and older. Participants will be randomized 1:1 to DTX301 or placebo and followed closely for 36-64 weeks. Between Week 36 and Week 64, eligible participants will cross over and receive DTX301 if they had previously received placebo, and some who received DTX301 may receive placebo. The planned study duration is up to 324 weeks. Upon completion of this study or early withdrawal, all participants who received DTX301 are invited to enroll in the Disease Monitoring Program (DMP) for follow-up for up to an additional 5 years.

Eligibility

Age

12 - No limit years

Sex

ALL

Healthy Volunteers

Inclusion Criteria

•Confirmed clinical diagnosis of late-onset OTC deficiency with historical documentation by enzymatic (ie, liver biopsy), biochemical (ie, hyperammonemia in the presence of elevated plasma glutamine, low citrulline, and elevated spot urine orotic acid), or molecular testing (ie, OTC analysis)
•Free from symptomatic hyperammonemia and has not required emergent active intervention for hyperammonemia within 4 weeks before screening/baseline
•If on ongoing daily ammonia scavenger therapy, must be at stable daily dose(s) for ≥ 4 weeks prior to screening
•If on a protein-restricted diet, must be on a stable total daily protein intake that does not vary more than 20% for ≥ 4 weeks prior to screening
•From the time written informed consent through Visit 28, females of childbearing potential and fertile males must consent to use highly effective contraception. If female, agree not to become pregnant. If male, agree not father a child or donate sperm

Exclusion Criteria

•Significant hepatic inflammation or cirrhosis
•Estimated glomerular filtration rate \< 60 mL/min/1.73 m2 at screening by the 2021 CKD-EPI creatinine-based formula (Inker et al., 2021) for patients ≥ 18 years of age or the Schwartz bedside formula (Schwartz and Work, 2009) for patients \< 18 years of age
•Evidence of active hepatitis B virus (HBV) or hepatitis C virus (HCV) infection, documented by current use of antiviral therapy for HBV or HCV or by hepatitis B surface antigen (HBsAg) or HCV RNA positivity
•Active infection (viral or bacterial)
•Detectable pre-existing antibodies to the AAV8 capsid
•Presence or history of any condition that, in the view of the Investigator, would interfere with participation, pose undue risk, or would confound interpretation of results
•Participation (current or previous) in another gene transfer study

Locations (16)

University of California

Los Angeles, California, United States

University of Colorado

Aurora, Colorado, United States

Ann & Robert H. Lurie Children's Hospital of Chicago

Chicago, Illinois, United States

University Hospitals Cleveland Medical Center

Cleveland, Ohio, United States

Hospital Italiano de Buenos Aires

Buenos Aires, Argentina

Clinica Universitaria Reina Fabiola

Córdoba, Argentina

Hospital de Clinicas de Porto Alegre

Porto Alegre, Brazil

The Hospital for Sick Children

Toronto, Ontario, Canada

Hopital Femme Mere Enfant

Bron, France

Necker-Enfants Maladas Hospital

Paris, France

Key Dates

Start Date

October 18, 2022

Primary Completion Date

September 1, 2027

Completion Date

March 1, 2031

Last Updated

February 17, 2026

Enrollment

ESTIMATED participants

Conditions

OTC Deficiency

Interventions

DTX301

GENETIC

Placebo

OTHER

Oral Corticosteroids

DRUG

Placebo for oral corticosteroids

DRUG

Sodium Acetate

DRUG

Study for Adolescents and Adults With Ornithine Transcarbamylase Deficiency to Evaluate Safety and Tolerability of ARCT-810

NCT05526066

Ornithine Transcarbamylase DeficiencyOTC Deficiency+1 more

View study

Data Source & Attribution

This clinical trial information is sourced from ClinicalTrials.gov, a service of the U.S. National Institutes of Health.

ClinicalTrials.gov last update: February 17, 2026Data synced to Clareo: March 29, 2026

Modifications: This data has been reformatted for display purposes. Eligibility criteria have been parsed into inclusion/exclusion sections. Location data has been geocoded to enable distance-based search. For the authoritative and most current information, please visit ClinicalTrials.gov.

Neither the United States Government nor Clareo Health make any warranties regarding the data. Check ClinicalTrials.gov frequently for updates.

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