Prime Medicine doses first patient in Wilson disease gene therapy trial

Cambridge, Massachusetts - Prime Medicine Inc. has initiated the initial patient enrollment for its groundbreaking Phase 1/2 clinical trial of PM577a, a novel gene therapy aimed at treating Wilson disease caused by the H1069Q mutation in the ATP7B gene. This marks the first clinical study of Prime Medicine's liver-focused gene editing technology and the debut of their in vivo Prime Editing approach.

PM577a represents a one-time treatment strategy to rectify the H1069Q mutation, which predominantly affects individuals of North American and European descent. The U.S. Food and Drug Administration has bestowed Rare Pediatric Disease designation upon PM577, a distinction reserved for therapies addressing serious or life-threatening conditions prevalent among children and adolescents under 18 years old, with a patient count falling below 200,000 in the United States.

Companies granted this designation may be eligible for a Priority Review Voucher. The Phase 1/2 trial is an open-label, global investigation designed to assess the safety, tolerability, and preliminary clinical efficacy of escalating doses of PM577a in adults and adolescents afflicted with Wilson disease and carrying at least one H1069Q allele.

Clinical enrollment will commence with stable adults currently receiving standard-of-care therapy. Efficacy assessments will encompass copper efflux via 64Cu PET, serum ceruloplasmin, non-ceruloplasmin-bound copper, and 24-hour urinary copper excretion. Discontinuation of baseline standard-of-care treatments will also be evaluated.

Anticipated data release from initial clinical observations is scheduled for 2027. Wilson disease is a genetic disorder characterized by impaired hepatic copper transport due to loss-of-function mutations in the ATP7B gene. Existing treatments entail copper chelators and zinc salts, necessitating lifelong daily administration, with liver transplantation serving as the exclusive curative option currently available.

Prime Medicine is concurrently investigating additional candidates for other ATP7B mutations, including a preclinical candidate targeting the R778L mutation prevalent in East Asian populations.