After a turbulent path to approval, a subset of patients with Duchenne muscular dystrophy (DMD) have a new medication, the first to get the FDA’s go-ahead for their illness. But approval came with a critical caveat: because pivotal trials didn’t establish clinical efficacy, the manufacturer must conduct a postmarketing trial or the drug could be pulled from the market.
Eteplirsen, marketed as Exondys 51, is indicated specifically for patients with a confirmed mutation of the dystrophin gene amenable to exon 51 skipping, which affects about 13% of patients with DMD. Patients with DMD have no or inadequate dystrophin, a protein that helps keep muscle cells intact. Worldwide, DMD affects about 1 of every 3600 male infants; cases among girls are very rare. Eteplirsen is intended to remove exon 51 from premessenger RNA, which ultimately produces a truncated dystrophin protein.
Voelker R. First DMD Drug Gains Approval. JAMA. 2016;316(17):1756. doi:10.1001/jama.2016.15537