Sarepta Slumps After FDA Says Duchenne Drug Efficacy Unproven

  • Stock down as much as 60%, biggest drop since November 2013
  • Effects `too small and variable, FDA staff says in report

Sarepta Therapeutics Inc.sank as much as 60 percent, the most since November 2013, after the U.S. Food and Drug Administration staff said its experimental drug aimed at treating Duchenne muscular dystrophy hasn’t been proven to work in clinical trials.

The stock was down 56 percent to $13.90 at 9:35 a.m. in New York. A competing drug from BioMarin Pharmaceutical Inc. was formally rejected by the FDA earlier this week. The agency is scheduled to give a final decision on Sarepta’s drug by Feb. 26.

Effects patients may have seen while on the drug, called eteplirsen, are “too small and variable, in the context of a poorly-controlled trial, to be reliably attributed to drug treatment,” FDA staff wrote in a report Friday, ahead of an advisory committee meeting Jan. 22 to discuss the treatment.

The report, coming a day after the FDA rejected BioMarin’s medication, is a major blow for patients who suffer a horrible disease that has no approved treatment. It will leave investors questioning how drugmakers could improve their chances for approval of drugs for a disease that afflicts a tiny segment of the population.

Reviewers who weighed in on eteplirsen wrote that “the data overall did not provide statistical evidence to support the efficacy” in Duchenne patients.

Duchenne muscular dystrophy is a deadly genetic disease that usually affects young boys. It’s a progressive disease in which the body lacks a protein, called dystrophin, that keeps muscles intact. It strikes in childhood, and patients typically end up in wheelchairs. Many die by age 25 from lung disorders, according to the National Institutes of Health.

Sarepta studied 12 Duchenne patients, some who received eteplirsen and others who received a placebo for 24 weeks. All the patients were then switched to eteplirsen for about three years. The study failed to meet its primary goal of increasing levels of the protein dystrophin, according to the report. The FDA staff also said that the ability of patients on the drug to function at basic tasks like rising from the floor and walking for six minutes was similar to patients historically who received intensive supportive care.

“Although FDA is prepared to be flexible with respect to a devastating illness with no treatment options, we cannot approve drugs for which substantial evidence of effectiveness has not been established,” the staff wrote in the report, noting no final conclusions on the drug had been reached.

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