PM359

June 22, 2026: Prime Medicine, Inc. (NASDAQ: PRME) announced the FDA granted Regenerative Medicine Advanced Therapy (RMAT) designation to PM359, an investigational autologous prime-edited hematopoietic stem cell therapy for p47phox-deficient chronic granulomatous disease (CGD). The RMAT decision was based on Phase 1/2 clinical data, including results previously published in The New England Journal of Medicine (December 2025).

The company said the initial Phase 1/2 results showed a single dose of PM359 led to rapid engraftment and durable, clinically meaningful restoration of immune cell function in both treated patients, with neutrophil activity above levels associated with clinical benefit, and a safety profile consistent with busulfan-based conditioning alone.

RMAT status enables earlier and more intensive FDA interactions and eligibility for rolling and priority review of a future Biologics License Application (BLA). PM359 also holds FDA Fast Track, Orphan Drug, and Rare Pediatric Disease designations, and is being evaluated in an ongoing Phase 1/2 multinational first-in-human trial.