FDA Grants Breakthrough Therapy Designation to First Exon 44 Skipping Drug for Duchenne Muscular Dystrophy

Investigational antisense oligonucleotide brogidirsen (NS-089/NCNP-02; NS Pharma, Paramus, NJ) has been granted breakthrough therapy designation by the Food and Drug Administration (FDA) for treatment of patients with Duchenne muscular dystrophy (DMD). On July 7, 2023, NS Pharma anounced the FDA granted rare pediatric designation to brogidirsen to treat DMD.

A Japanese, investigator-initiated, first-in-human clinical trial evaluating the safety and efficacy of brogidirsen demonstrated that treatment with the investigational agent was associated with maintenance or improvement in motor function and increased expression of the dystrophin protein in participants with DMD, indicating potential therapeutic efficacy. FDA breakthrough therapy designation was granted to brogidirsen based on these study results.

DMD is an incurable form of muscular dystrophy associated with progressive skeletal, cardiac, and respiratory muscle weakness; individuals with DMD have an average life expectancy of 26 years. In DMD, a genetic mutation in specific gene exons, or regions, prevents the production of the dystrophin protein essential for proper muscle function. Brogidirsen is designed as an exon skipping therapy, intended to bypass mutated exons to restore dystrophin production. Brogidirsen represents the world’s first exon 44 skipping drug, targeting exon 44.

Breakthrough therapy designation is intended to expedite drug development and approval. NS Pharma states that they are planning a phase 2 clinical study in the United States to further investigate brogidirsen, with details forthcoming.