CAMBRIDGE, Mass., July 23, 2026
Prime Medicine (Nasdaq: PRME) announced that the U.S. Food and Drug Administration (FDA) has cleared the Investigational New Drug (IND) application for PM577a, the company’s investigational in vivo Prime Editing therapy for H1069Q-mutated Wilson disease (WD). The FDA clearance, combined with the previously approved New Zealand Clinical Trial Application (CTA), establishes a global Phase 1/2 clinical development program for PM577a. The milestone enables patient enrollment in the United States, where the H1069Q mutation in the ATP7B gene is the most common genetic cause of Wilson disease. Prime Medicine expects to initiate the Phase 1/2 clinical trial during the second half of 2026, with initial clinical data anticipated in 2027.
Global Phase 1/2 Trial to Evaluate One-Time Prime Editing Therapy
The global Phase 1/2 study is an open-label, first-in-human clinical trial designed to evaluate the safety, tolerability, biological activity, and efficacy of ascending doses of PM577a in adults and adolescents with Wilson disease. The study will initially enroll clinically stable adult patients receiving current standard-of-care treatment. Researchers will assess treatment activity using several biomarkers, including 64Cu PET copper efflux imaging, serum ceruloplasmin, non-ceruloplasmin bound copper, 24-hour urinary copper excretion, and liver copper measurements obtained through biopsy. The program aims to determine whether a single intravenous infusion of PM577a can restore normal copper metabolism by correcting the underlying genetic mutation.
PM577a Targets the Most Common ATP7B Mutation Causing Wilson Disease
PM577a is part of Prime Medicine’s LNP-formulated Prime Editing platform, developed to correct disease-causing ATP7B gene mutations directly in liver cells. The therapy specifically targets the H1069Q mutation, which accounts for approximately 30% to 50% of Wilson disease-associated variants in the United States and Europe. Prime Medicine also plans to expand the program with additional Prime Editing candidates, including a preclinical therapy targeting the R778L mutation, the most common ATP7B mutation in East Asian populations. The company’s long-term strategy is to develop therapies capable of addressing the majority of Wilson disease-causing genetic variants worldwide.
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Prime Editing Aims to Deliver a Curative Option for Wilson Disease
Wilson disease is a rare inherited disorder caused by mutations in the ATP7B gene, resulting in the toxic accumulation of copper in the liver, brain, kidneys, and other organs. Existing treatments, including copper chelators and zinc therapy, require lifelong administration, are associated with adherence challenges and side effects, and do not cure the disease. Liver transplantation remains the only curative option but is limited by donor availability and surgical risks. Prime Medicine believes PM577a has the potential to become a one-time curative genetic therapy by correcting the disease at its genetic source, offering a transformative treatment option for patients living with Wilson disease.
Source: Prime Medicine press release
