NS Pharma Inc, a subsidiary of Japan-based Nippon Shinyaku Co Ltd (TYO:4516), announced on Monday that the National Center of Neurology and Psychiatry (NCNP) has presented 4.5-year safety and efficacy data for brogidirsen (NS-089/NCNP-02) for the treatment of Duchenne muscular dystrophy (DMD) at the 2026 MDA Clinical & Scientific Conference.

Brogidirsen is an antisense oligonucleotide co-discovered by Nippon Shinyaku and NCNP as an investigational therapy for DMD patients with dystrophin gene mutations that are amenable to exon 44 skipping.

The first-in-human Phase 1/2 open-label investigator-initiated clinical trial conducted by NCNP and the subsequent Phase 2 open-label extension trial conducted by Nippon Shinyaku evaluate the safety and efficacy of brogidirsen in six participants who received weekly IV dosing of brogidirsen.

From the initiation of weekly administration, participants maintained motor function in assessments such as North Star Ambulatory Assessment (NSAA). All participants, including those who transitioned to full-time wheelchair use due to disease progression, maintained their total scores in Performance of Upper Limb (PUL 2.0).

No serious or severe adverse events were reported related to long-term brogidirsen administration.

These findings support the potential of brogidirsen to modify the progression of DMD. This extension trial is ongoing to investigate the safety and efficacy of longer-term administration.

An ongoing global Phase II study of brogidirsen is also being conducted by Nippon Shinyaku and NS Pharma to further evaluate the safety and efficacy of brogidirsen.