Sarepta Therapeutics ($SRPT) got a go-ahead from U.S. regulators to file a new drug application for its lead drug eteplirsen based on existing studies. The Cambridge, MA-based biotech company plans to file an early application for the RNA drug to treat Duchenne muscular dystrophy, a rare muscle-wasting disease that robs mostly boys of their ability to walk.
Based on a meeting with the FDA yesterday, Sarepta said that the company plans to file an NDA for eteplirsen in the first half of 2014. Regulators declined to commit to a measure of dystrophin in muscle fiber as a surrogate endpoint for Accelerated Approval, which many of the most ardent backers were watching as a sign of the agency's full embrace of the program.
Shares of Sarepta dropped 14.9% to $38.50 as of 12:03 pm ET, with the price of the stock likely to change as analysts dissect comments and statements from the company and what they mean for the future of eteplirsen.
Sarepta, whose stock price has skyrocketed 444.95% over the past year, has pushed for a rapid path to the market for eteplirsen after a series of results from a 12-patient Phase IIb study of the therapy that showed impressive benefits to boys with the disease based on results in a 6-minute walk test and other data. Boys have shown improvements in their walking ability after beginning treatment on eteplirsen, and the biotech group has reported benefits from more than a year and a half of tracking patients in the trial. The company said that the FDA was "open to considering an NDA based on these data for filing."President and CEO Chris Garabedian
"We are encouraged by the feedback from the FDA and believe that data from our ongoing clinical study merits review by the Agency and will be sufficient for an NDA filing," Chris Garabedian, president and chief executive officer of Sarepta, said in a statement. "We plan to work closely with the FDA to prepare an NDA submission in the first half of 2014 as we continue to prepare for our confirmatory study and our manufacturing scale up."
Sarepta has been racing against GlaxoSmithKline ($GSK), which is developing a rival therapy called drisapersen in partnership with Prosensa ($RNA). Glaxo has also revealed some upbeat Phase II data and is expected to report more results later this year, putting the company on track to seek approval of its DMD therapy next year as well.
These are exciting times for the DMD community, which lacks approved therapies to reverse the disease, and advocates have been pushing for swift approval of eteplirsen. They may get their way, but the information from Sarepta indicates that the agency has made no promises about approving the drug. However, the FDA has bolstered its efforts to provide rapid reviews of therapies for treating patients in need. Duchenne typically strikes boys in their youth and leads to premature death in their mid-twenties, so there's a huge need for therapies to give them a shot at better lives.
Like GSK's drug, Sarepta's lead therapy targets exon skipping 51 and is expected to combat cases of DMD with genotypes that can benefit from the treatment. The company plans to treat patients with multiple genotypes in its confirmatory trial for eteplirsen, while the company advances other candidates in preclinical development for exon skipping 45, 53, 50 and 44. Garabedian said during a conference call that his company plans to file an IND for the first of those therapies by mid-2014 with others to follow.