Japanese pharma Nippon Shinyaku (NS Pharma) has scored US Food and Drug Administration (FDA) approval for its Duchenne muscular dystrophy drug viltolarsen, now named Viltepso.
The approval will see Viltepso enter a competitive market and likely head into a rivalry with Sarepta’s Vyondys 53 (golodirsen), which gained FDA approval last December.
The approval of Viltepso was based on two clinical studies with a total of 32 patients with genetically confirmed DMD. The genetic disorder is caused by mutations in the DMD gene that results in an absence of dystrophin, which is needed to help keep muscle cells intact.
NS Pharma’s drug has been approved for the treatment of DMD patients who have a confirmed mutation of the DMD gene with exon 53 mutations. This represents around 8% of the overall DMD population, while those with the exon 51 mutation account for around 13%.
In one of the two studies, NS Pharma’s drug increased dystrophin production, with levels increasing on average by 0.6% at baseline to 5.9% at week 25.
The FDA said the data demonstrated an increase in dystrophin levels that is ‘reasonably likely’ to lead to clinical benefit in DMD patients with exon 53 mutations.
“For decades, neurologists who treat DMD have hoped for the discovery of therapies capable of significantly improving dystrophin production, and the magnitude of dystrophin increases observed with Viltepso are impressive,” said study investigator Vamshi Rao, Ann & Robert H. Lurie Children’s Hospital of Chicago, US.
“The approval of Viltepso is an exciting development for those DMD patients who are amenable to exon 53 skipping therapy and may rapidly become a foundational treatment for these patients,” he added.
Following the approval, NS Pharma is required to conduct a confirmatory clinical trial to demonstrate the drug’s clinical benefit. The study will assess whether Viltepso improves the length of time that DMD patients with the indicated mutations are able to stand.
Like NS Pharma, Sarepta is conducting a confirmatory trial of Vyondys 53 after winning initial approval to determine the drug’s clinical benefit. It is the company’s second DMD drug after Exondys 51 (eteplirsen), the first disease-modifying treatment for the disease to be introduced in the US.
Vyondys 53 was initially rejected by the FDA in August 2019, after concerns were raised when kidney toxicity caused by the drug was observed in preclinical studies.
Although no kidney toxicity was observed in the Viltepso clinical studies, the FDA has recommended that kidney function should be monitored in patients taking the drug due to the limited data available.