The FDA granted accelerated approval to Viltepso(viltolarsen), developed by NS Pharma, Inc., a unit of Japanese company Nippon Shinyaku Co., Ltd., on August 12, 2020, for the treatment of patients with Duchenne muscular dystrophy (DMD) who are amenable to exon 53 skipping therapy.Duchenne muscular dystrophy (DMD) is a genetic disorder caused by mutations to the dystrophin gene which is responsible for the production of dystrophin muscle protein. The lack of dystrophin causes progressive muscle weakness and premature death.Approximately 8% of patients with DMD have a mutation that is amenable to exon 53 skipping. Sarepta Therapeutics' Vyondys 53 (golodirsen) was given accelerated approval by the FDA in December last year to treat the same indication.As part of the accelerated approval process, the FDA has required the company to conduct a clinical trial to confirm the drug’s clinical benefit. The ongoing study is designed to assess whether Viltepso improves the time to stand for DMD patients with this confirmed mutation. If the trial fails to verify clinical benefit, the FDA may initiate proceedings to withdraw approval of the drug.The company has priced the drug at about $733,000 per year for patients weighing 30 kilograms.In March this year, Viltepso was approved in Japan for the treatment of patients with DMD who are amenable to exon 53 skipping therapy.