Potential Therapy for Duchenne MD Gets FDA's Rare Pediatric Disease Designation

The developer of eteplirsen announced on August 21 that the U.S. Food and Drug Administration (FDA) has granted Rare Pediatric Disease Designation for the medication, a potential therapy for patients with Duchenne muscular dystrophy (DMD) who are amenable to skipping exon 51. Sarepta Therapeutics noted that the Rare Pediatric Disease Designation supplements the Orphan Drug Designation and Fast Track Status that the FDA had previously granted for eteplirsen.

Under the designation, the regulatory clearance of eteplirsen will trigger the award of a Rare Pediatric Disease Priority Review Voucher to the company. This provides for Priority Review for a future marketing application after giving the FDA a 90-day notice of its intention to use it, a valuable benefit.

DMD is an X-linked rare degenerative neuromuscular disorder causing severe progressive muscle loss and premature death. One of the most common fatal genetic disorders, DMD affects approximately 1 in every 3,500 boys born worldwide. A devastating and incurable muscle-wasting disease, DMD is associated with specific errors in the gene that codes for dystrophin, a protein that plays a key structural role in muscle fiber function. Progressive muscle weakness in the lower limbs spreads to the arms, neck and other areas. Eventually, increasing difficulty in breathing due to respiratory muscle dysfunction requires ventilation support, and cardiac dysfunction can lead to heart failure. The condition is universally fatal, and death usually occurs before the age of 30.

Eteplirsen is designed to address the underlying cause of DMD by enabling the production of a functional dystrophin protein. Promoting the synthesis of a truncated dystrophin protein is intended to stabilize or significantly slow the disease process and prolong and improve the quality of life for patients with DMD.

Data from clinical studies of eteplirsen in DMD patients have demonstrated a broadly favorable safety and tolerability profile and restoration of dystrophin protein expression.

Eteplirsen uses Sarepta's novel phosphorodiamidate morpholino oligomer (PMO)-based chemistry and proprietary exon-skipping technology to skip exon 51 of the dystrophin gene enabling the repair of specific genetic mutations that affect approximately 13% of persons with DMD. By skipping exon 51, eteplirsen may restore the gene's ability to make a shorter but still functional form of dystrophin from messenger RNA (mRNA). Promoting the synthesis of a truncated dystrophin protein is intended to stabilize or significantly slow the disease process and prolong and improve the quality of life for patients with DMD.

The FDA defines a "rare pediatric disease" as a disease that affects fewer than 200,000 individuals in the United States, primarily aged from birth to 18 years. Under the FDA's Rare Pediatric Disease Priority Review Voucher program, a sponsor who receives an approval of a new drug application (NDA) or biologics license application (BLA) for a rare pediatric disease may be eligible for a voucher, which can be redeemed to obtain priority review for a subsequent marketing application for a different product. The Priority Review Voucher may be sold or transferred an unlimited number of times.