(Adds UnitedHealth, Aetna)
By Natalie Grover
Oct 7 (Reuters) - Health insurer Anthem Inc said it will not cover Sarepta Therapeutics Inc's drug to treat the rare condition of Duchenne muscular dystrophy (DMD), calling it "investigational and not medically necessary."
The U.S. Food & Drug Administration approved the drug last month under pressure from patient advocates, even though an outside panel of experts and the agency's own reviewers had questioned its efficacy.
Sarepta has priced the drug, called Exondys 51, at about $300,000 per patient per year.
The Cambridge, Massachusetts-based company's stock was down about 7 percent on Friday.
UnitedHealth Group Inc., the largest U.S. health insurer, does plan to cover the drug, a spokesman said on Friday. Aetna Inc plans to conduct a full clinical review to determine its coverage policy, spokesman T.J. Crawford said on Friday.
Anthem, the second-largest U.S. health insurer, said on Thursday on its website that clinical benefit, including improved motor function, had not been demonstrated by Exondys 51.
"Exondys 51 failed to show it improves health outcomes, and therefore it is not a covered benefit for our members," Anthem spokeswoman Leslie Porras said in an emailed statement on Friday.
DMD, a rare genetic muscle-wasting condition, typically emerges in childhood and mostly affects boys. It causes weakness in the arms and legs and eventually affects the lungs and heart. Patients frequently die in their 20s or 30s, according to the National Institutes of Health.
The drug is designed to treat about 13 percent of all DMD patients, or some 1,300 to 1,900 people in the United States.
The FDA gave it accelerated approval based on data believed to predict a clinical benefit. Sarepta has to prove that benefit in a subsequent clinical trial, the outcome of which is expected to take at least a few years.
To keep health insurance affordable, companies need to ensure that they are paying for safe and effective treatments, said Diana Zuckerman, president of non-profit organization National Center for Health Research.
"When FDA fails to ensure those standards, then 'FDA approval' is no longer a gold standard that insurance companies can rely on," she said.
Shares of Sarepta, which has announced DMD collaborations with Catabasis Pharmaceuticals Inc and Summit Therapeutics Plc, have more than doubled since the FDA announced its approval on Sept. 19.
Reporting by Natalie Grover in Bengaluru and Caroline Humer in New York; Editing by Shounak Dasgupta and Steve Orlofsky