Prime Medicine Announces Breakthrough Clinical Data Showing Rapid Restoration of DHR Positivity After Single Infusion of PM359, an Investigational Prime Editor for Chronic Granulomatous Disease

Core Insights - Prime Medicine announced positive initial data from the first patient dosed in its Phase 1/2 clinical trial of PM359 for Chronic Granulomatous Disease (CGD), demonstrating a significant restoration of NADPH oxidase activity and an encouraging safety profile [1][3][4] Company Overview - Prime Medicine is a biotechnology company focused on developing one-time curative genetic therapies using its proprietary Prime Editing technology, which allows precise genome editing to correct genetic mutations [12][13] Clinical Trial Results - The initial data from the trial showed that a single dose of PM359 led to 58% DHR positivity by Day 15 and 66% by Day 30, significantly exceeding the minimum threshold for clinical benefit of 20% [1][4] - Rapid engraftment was observed, with neutrophil engraftment confirmed on Day 14 and platelet engraftment on Day 19, nearly twice as fast as existing gene editing technologies [5] Safety Profile - PM359 was generally well-tolerated, with adverse events consistent with those observed during myeloablative conditioning, and no serious adverse events related to PM359 reported [6][7] Future Development Plans - Prime Medicine plans to explore external opportunities for the continued clinical development of PM359, while focusing its resources on advancing its in vivo liver franchise targeting Wilson's Disease and Alpha-1 Antitrypsin Deficiency [8][9] Disease Context - Chronic Granulomatous Disease (CGD) is a rare inherited disorder characterized by severe infections due to mutations affecting the NADPH oxidase complex, with an estimated occurrence of 1 in 100,000 to 1 in 200,000 births in the U.S. [2][11]