Dyne Therapeutics Receives Breakthrough Therapy for DYNE-251 in Duchenne Muscular Dystrophy
Monday, August 04, 2025
Dyne Therapeutics has announced that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy Designation for DYNE-251, a treatment for patients with Duchenne muscular dystrophy (DMD) who are eligible for exon 51 skipping.
DYNE-251 is an investigational therapy that combines a phosphorodiamidate morpholino oligomer (PMO) with a transferrin receptor-binding fragment. This combination is intended to support dystrophin production in muscle and the central nervous system, contributing to improved muscle function.
Duchenne muscular dystrophy is a rare genetic disorder caused by mutations in the DMD gene, resulting in the lack of dystrophin protein. The condition primarily affects males, with around 12,000 cases in the U.S. and 16,000 in the EU. Symptoms often begin in early childhood and progressively worsen, leading to loss of mobility, respiratory difficulties, and cardiac complications. There remains a strong need for effective treatments that improve quality of life and slow disease progression.
The designation is supported by clinical data from the ongoing DELIVER trial.
DYNE-251 is designed to enable the production of near full-length dystrophin, a protein vital for muscle function. The treatment has shown sustained functional improvement over an 18-month period in key clinical measures, including time to rise and stride velocity. This development represents a significant step in addressing the needs of DMD patients.
This marks the second Breakthrough Therapy Designation received by Dyne Therapeutics, following a similar designation earlier in the year for DYNE-101 in the treatment of myotonic dystrophy type 1. Breakthrough Therapy Designation is intended to accelerate the development and review of treatments that may offer substantial improvements over existing therapies for serious conditions. The designation provides benefits such as enhanced guidance from the FDA, frequent communication regarding regulatory strategy, and eligibility for rolling and priority review, which may shorten the approval timeline.
DYNE-251 has already received Fast Track, Orphan Drug, and Rare Paediatric Disease designations in the U.S., as well as Orphan Drug designation in the EU.
The DELIVER trial is a global, double-blind, placebo-controlled Phase 1/2 study assessing the safety, tolerability, and efficacy of DYNE-251 in DMD patients amenable to exon 51 skipping. The selected dose for the registrational cohort is 20 mg/kg administered every four weeks. The primary endpoint is the change in dystrophin protein levels at six months, measured by Western blot.
Dyne has completed enrolment of 32 patients in the Registrational Expansion Cohort of the DELIVER trial, with data expected in late 2025. A Biologics License Application (BLA) for accelerated approval in the U.S. is planned for early 2026. The company also aims to pursue regulatory approvals outside the U.S.
Source: dyne-tx.com
