NS Pharma's Duchenne Treatment Gains FDA’s Rare Pediatric Disease Status, Paving Way For New Hope

NS Pharma's exon-skipping treatment for Duchenne muscular dystrophy (NS-050/NCNP-03) has received a rare pediatric disease designation from the U.S. FDA. This status is reserved for therapies targeting severe or life-threatening conditions that affect children and impact fewer than 200,000 patients in the United States.

Yukiteru Sugiyama, PhD, NS Pharma president, mentioned in a company press release. “We are grateful for this designation, which can help us accelerate the development of this therapy for Duchenne. The journey from first symptom to diagnosis and finally treatment can be long and challenging for patients with rare diseases and their caregivers.”

Duchenne muscular dystrophy (DMD) results from the absence of dystrophin, a crucial protein that shields muscles from contraction-related damage. This disorder leads to gradual muscle weakness and wasting, beginning in the hips and upper legs before spreading to other areas. The DMD gene holds the blueprint for producing dystrophin.

Genes are made up of segments called introns and exons. When a protein needs to be made, a molecule known as precursor messenger RNA (pre-mRNA) is created to copy the gene's instructions. The introns are cut out of the pre-mRNA, leaving only the exons in the final mature mRNA, which the cell then uses to build proteins according to the instructions.

Maintaining the integrity of introns and exons is essential for producing accurate, mature mRNA. If the instructions for creating a healthy protein are flawed or missing, the mature mRNA will relay incorrect building instructions, resulting in proteins of improper length and shape that fail to function correctly.

Exon-skipping therapies offer a solution by prompting muscle cells to bypass specific exons during the gene reading process, leading to the production of a shortened but functional version of dystrophin. In the U.S., four exon-skipping treatments for Duchenne muscular dystrophy (DMD) have received approval. Among them is Viltepso (viltolarsen), which targets exon 53.

NS-050/NCNP-03, another exon-skipping therapy, employs antisense oligonucleotides—a type of short genetic strand—to skip exon 50. This approach is suitable for approximately 4% of the DMD population. According to NS Pharma, NS-050/NCNP-03 is designed to produce a functional, albeit shorter, dystrophin protein that may help slow down muscle function decline.

This therapy is being evaluated in a Phase 1/2 clinical trial called Meteor50 (NCT06053814), which will be conducted in Japan and the U.S. The study will involve DMD patients who can walk and are eligible for exon 50 skipping. Participants will receive escalating doses of NS-050/NCNP-03 weekly for 12 weeks, followed by a 24-week period (about six months) of treatment with a selected dose of the therapy.

Key outcome measures will include the frequency and severity of adverse effects, pharmacological evaluations, and dystrophin production levels. Similar to Viltepso, NS-050/NCNP-03 was developed in collaboration with the National Center of Neurology and Psychiatry and Nippon Shinyaku, the parent company of NS Pharma.