Dyne Therapeutics’ DYNE-251 Gains Orphan Drug Status in Japan for Duchenne Muscular Dystrophy

Dyne Therapeutics announced that Japan’s Ministry of Health, Labour and Welfare (MHLW) has granted Orphan Drug designation to DYNE-251, a therapy in development for Duchenne muscular dystrophy (DMD) patients with mutations amenable to exon 51 skipping. The treatment is currently being evaluated in the ongoing global Phase 1/2 DELIVER clinical trial.

Doug Kerr, Dyne’s chief medical officer, highlighted the promising results seen so far, noting sustained functional improvements driven by increased dystrophin expression. He emphasized that this designation in Japan complements similar statuses granted in the U.S. and Europe, reinforcing DYNE-251’s potential as a next-generation exon 51 skipping therapy targeting one of the most prevalent and severely affected subgroups of DMD patients.

In Japan, Orphan Drug status is awarded to treatments for rare diseases affecting fewer than 50,000 people and offers benefits such as development cost subsidies and up to 10 years of market exclusivity if approved. DYNE-251 has also received Breakthrough Therapy, Fast Track, and Rare Pediatric Disease designations from the U.S. FDA, alongside Orphan Drug status from both the FDA and the European Medicines Agency.