European Commission Grants Orphan Drug Designation to Dyne Therapeutics’ DYNE-251 for Duchenne Muscular Dystrophy

April 25, 2025 /Pharmaceutical-technology/

The European Commission (EC) has granted orphan drug designation to Dyne Therapeutics’ DYNE-251 for the treatment of Duchenne muscular dystrophy (DMD).

This designation is a significant step in the development of DYNE-251, which is currently being assessed in the Phase I/II DELIVER trial involving individuals with DMD who are amenable to exon 51 skipping.

Long-term clinical data from the DELIVER trial, at the selected registrational dose, have indicated functional improvement. These evaluations include Stride Velocity 95th Centile (SV95C), an objective digital outcome recognised as a primary endpoint in European DMD studies.

Dyne Therapeutics is committed to pursuing accelerated approval pathways for DYNE-251 globally, particularly for DMD patients who could benefit from exon 51 skipping therapies.

The company has enrolled 32 participants in the registrational expansion cohort of the DELIVER trial, with data anticipated by late 2025. Furthermore, Dyne Therapeutics expects to submit a biologics license application for accelerated approval in the US in early 2026.

According to the company, DYNE-251 consists of a phosphorodiamidate morpholino oligomer conjugated to a fragment antibody that binds to the transferrin receptor 1, facilitating targeted delivery to muscle tissue.

This therapeutic approach aims to promote exon skipping within the nucleus, potentially halting or reversing the progression of DMD, a rare genetic disorder characterised by mutations in the dystrophin protein gene, which is essential for normal muscle cell function.

Dyne Therapeutics’ chief medical officer, Doug Kerr, stated, “We are pleased that the EC has granted orphan drug designation to DYNE-251, reinforcing our belief that our next-generation exon 51 skipping investigational therapy for DMD may be able to bring clinically meaningful functional improvement to those living with this devastating disease.”

The US Food and Drug Administration has previously granted orphan drug, rare paediatric disease, and fast track designations to DYNE-251.

In addition to DYNE-251, Dyne Therapeutics is expanding its DMD portfolio with preclinical programmes targeting other exons, including 44, 45, and 53.