A Phase 1/2/3 Study of UX701 Gene Therapy in Adults With Wilson Disease

Stage 1 (Phase 1/2) is an open-label safety and dose-finding stage designed to evaluate the safety and efficacy of 4 dose levels of UX701 to establish initial safety of UX701 and select a safe and efficacious dose for further evaluation. Stage 2 (Phase 3) is a randomized, open-label, active-controlled stage to evaluate the safety and efficacy of UX701 using the dose selected in Stage 1. Stage 3 is a long-term follow-up stage designed to evaluate the safety, efficacy, and clinical benefit of UX701 for at least 5 years from the time of UX701 administration.

Participants who receive UX701 will receive premedication, prophylactic oral corticosteroids and immunomodulation therapy.

Key Inclusion Criteria:

• Confirmed diagnosis of Wilson disease based on genetic confirmation of heterozygous or homozygous biallelic ATP7B mutation.
• Stable Wilson disease as evidenced by ongoing copper chelator (ie, penicillamine, trientine) and/or zinc therapy for at least 2 months at screening, with no medication or dose changes for at least 2 months at screening.
• Ongoing restriction of high copper containing foods for at least 2 months at Screening and continued through study participation.
• Willing and able to comply with all study procedures and requirements, including frequent blood collection, total urine collection over a 24-hour period, patient-reported outcome assessments, and long-term follow-up

Key Exclusion Criteria:

• Detectable pre-existing antibodies to the AAV9 capsid.
• Stage 1 only: History of copper chelator or zinc therapy noncompliance, in the Investigator's judgment, within 6 months prior to Screening.
• History of liver transplant.
• Active decompensated hepatic cirrhosis or history of hepatic encephalopathy.
• Significant hepatic inflammation as evidenced by laboratory abnormalities.
• Model for End-Stage Liver Disease (MELD) score > 13.
• Hemoglobin < 9 g/dL
• Presence of Stage 3 or higher chronic kidney disease based on estimated glomerular filtration rate < 60 mL/min/1.73 m2.
• Marked neurological deficit or compromise that, in the Investigator's opinion, would interfere with the subject's safety or ability to participate in the study.
• Moderate to severe depression, recent or active suicidal ideation with intent or suicidal behavior, psychosis, or unstable psychiatric illness.
• Known hypersensitivity to UX701 or its excipients, copper chelators, zinc, rituximab, tacrolimus, corticosteroids, or eculizumab that, in the Investigator's judgement, places the participant at increased risk for adverse events.
• Participation in another gene transfer study or use of another gene transfer product before or during study participation.
• Subjects with known hypersensitivity to amide-containing local anesthetics are excluded from participating in the optional liver biopsy substudy.

Note: Other protocol defined Inclusion/ Exclusion criteria may apply