CAMBRIDGE, Mass. — Prime Medicine, Inc. (Nasdaq: PRME), a biotechnology company committed to delivering a new class of differentiated one-time curative genetic therapies, today announced that the U.S. Food and Drug Administration (FDA) has cleared the Company’s Investigational New Drug (IND) application for PM577a, an investigational in vivo Prime Editor for Wilson disease (WD). With the IND cleared, PM577a may proceed to clinical study in the United States. Together with the Company’s previously announced New Zealand Clinical Trial Application (CTA) clearance, the IND clearance establishes a global Phase 1/2 program and opens participation to patients in the United States, where H1069Q is the single most common pathogenic variant causing WD.
“Wilson disease is a serious, progressive disorder with no approved curative option, and today’s standard of care requires lifelong therapy burdened by significant side effects and low adherence,” said Allan Reine, M.D., Chief Executive Officer of Prime Medicine. “With PM577a, we have the potential to offer a one-time therapy that corrects the disease at its genetic root. This clearance, alongside our recent New Zealand CTA, establishes a global Phase 1/2 program that reflects Prime’s confidence in our in vivo Prime Editing approach. We expect to initiate the Phase 1/2 trial in the second half of 2026 with initial clinical data anticipated in 2027, and we are committed to advancing this program with the rigor patients deserve.”
Phase 1/2 Clinical Trial
The Phase 1/2 clinical trial is an open-label, global, first-in-human study designed to evaluate the safety, tolerability, biological activity, and efficacy of ascending doses of PM577a in adults and adolescents with WD. The study will initially enroll adults who are clinically stable on standard-of-care therapy. Biological activity and efficacy assessments may include copper efflux by 64Cu PET, serum ceruloplasmin, non-ceruloplasmin bound copper, 24-hour urinary copper excretion, and hepatic copper by biopsy.
About PM577
PM577 is a family of LNP-formulated Prime Editing products designed to correct pathogenic ATP7B mutations in hepatocytes via a single intravenous infusion. Prime Medicine’s initial candidate, PM577a, targets the ATP7B H1069Q allele, which accounts for approximately 30–50% of WD-associated variants in the United States and Europe. The Company intends to develop additional products to address the majority of pathogenic variants on a global basis. Currently, a follow-on candidate is in pre-clinical development targeting R778L, the most common mutant allele in East Asian populations.
About Wilson Disease
Wilson disease is a rare, autosomal recessive disorder of hepatic copper transport caused by loss-of-function mutations in the ATP7B gene, affecting an estimated 1 in 30,000 individuals globally. Impaired biliary excretion drives progressive copper accumulation in the liver, followed by multi-organ involvement including the brain, kidneys, and cornea. Clinical manifestations range from asymptomatic hepatomegaly to decompensated cirrhosis and acute liver failure; neuropsychiatric complications affect approximately two-thirds of patients. Current pharmacologic therapies, copper chelators and zinc salts, are non-curative, require lifelong daily dosing under strict dietary conditions, carry tolerability challenges, and are associated with high non-adherence rates. Liver transplantation remains the sole curative option but is constrained by organ availability and carries substantial procedural risk.
About Prime Medicine
Prime Medicine is a leading biotechnology company dedicated to creating and delivering the next generation of gene editing therapies to patients. The Company is deploying its proprietary Prime Editing platform, a versatile, precise and efficient gene editing technology, to develop a new class of differentiated one-time curative genetic therapies. Designed to make only the right edit at the right position within a gene while minimizing unwanted DNA modifications, Prime Editors have the potential to repair almost all types of genetic mutations and work in many different tissues, organs and cell types. Taken together, Prime Editing’s versatile gene editing capabilities could unlock opportunities across thousands of potential indications. For more information, please visit www.primemedicine.com.
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