New muscular dystrophy drug wins FDA approval, but questions linger
Tentative approval has been granted by federal regulators for the first muscular dystrophy drug. The approval follows an intense public campaign from patients and doctors who pushed for the largely unproven medication.
The approval comes nearly five months after the Food and Drug Administration and a panel of outside advisers panned the drug, saying there was little evidence that it helped. But regulators faced a public backlash from patients’ families, politicians and physicians.
The FDA cleared Sarepta Therapeutics’ Exondys 51 for a rare form of Duchenne muscular dystrophy, a deadly inherited disease that affects boys. It’s the first FDA approval for the degenerative condition, which causes muscle weakness, loss of movement and eventually death.
The approval was based on a company study of just 12 boys. The agency is requiring Sarepta to conduct a larger study examining whether Exondys 51 results in improved movement and function for patients. If the study fails to shows it helps, the FDA said it could withdraw the drug.
Duchenne muscular dystrophy is a rare disease, affecting about 1 of every 3,600 boys worldwide and usually causing death by age 25, according to the National Institutes of Health.
The new drug targets a genetic mutation that affects about 13 percent of Duchenne patients. Previously there were no U.S.-approved drugs to fight the disease, though steroid drugs have been used to slow the loss of muscle strength.
Pat Furlong, a patient advocate who lost two sons to the disease, called the announcement “an extraordinary win.”
“I think this is a collaborative effort that shows the FDA, companies and the patient community can work together toward a single goal, and that is improving the lives of patients,” said Furlong, founder and president of Parent Project Muscular Dystrophy, a nonprofit that helped fund travel and other expenses related to the study.
The FDA cleared Sarepta’s drug under its accelerated approval program, reserved for drugs that show promising early results that have not been confirmed. The drug acts on a protein called dystrophin, which plays a role in the growth of muscle fibers. The 12-patient study showed an increase in dystrophin “that is reasonably likely to predict” benefit in some patients, the FDA said in its announcement.
“Accelerated approval makes this drug available to patients based on initial data, but we eagerly await learning more about the efficacy of this drug through a confirmatory clinical trial,” said Dr. Janet Woodcock, director of the FDA’s drug center.
FDA staff said at a public meeting in April that they “strongly encouraged” Sarepta to conduct a larger, more comprehensive study of its drug with a randomly selected control group of patients receiving a placebo - considered the gold standard of study design.
An outside panel of experts voted 7-3 at the meeting that the drug did not show effectiveness in treating the disease. The FDA is not required to follow the advice of its advisory panels, though it often does.
Wall Street analysts called the approval decision surprising and perplexing.
“Ultimately, it appears to us that the FDA bowed to external pressure from patient advocates and others who demanded that a safe and potentially efficacious drug be made available,” said Leerink Swann analyst Joseph Schwartz, in a note to investors.
Shares of Sarepta Therapeutics jumped more than 90 percent to $25.54 in afternoon trading. The company is based in Cambridge, Massachusetts.