This study is a randomized, double-blind, placebo-controlled, seamless, adaptive Phase 1/2/3 clinical study of UX701 in patients with Wilson disease.~Stage 1 (Phase 1/2) is a nonrandomized, open-label safety and dose-finding stage designed to evaluate the safety and efficacy of 3 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, double-blind, placebo-controlled stage designed to evaluate the safety and efficacy of UX701 using the dose selected in Stage 1. Stage 3 is designed to evaluate the long-term safety, efficacy, and clinical benefit of UX701. All participants will be followed for at least 5 years from the time of UX701 administration.~Participants who receive UX701 will receive prophylactic oral corticosteroids. Participants who receive placebo will receive placebo oral corticosteroids to maintain the study blind.
The primary objectives of this study are to evaluate the safety of single IV doses of UX701 in patients with Wilson disease, to select the UX701 dose with the best benefit/risk profile based on the totality of safety and efficacy data and to evaluate the effect of UX701 on copper regulation.