FDA approves $3.2 million gene therapy for rare muscular dystrophy in kids ages 4 and 5

The US Food and Drug Administration has approved the first gene therapy to treat a rare and devastating muscle disease but limited the approval to kids ages 4 and 5 based on available evidence.

The drug, from biotech company Sarepta Therapeutics, will need to prove in an ongoing clinical trial that it improves physical function and mobility in patients with Duchenne muscular dystrophy in order to stay on the market, the FDA said Thursday. The therapy was approved under the accelerated approval pathway, which clears medicines for diseases where they’re urgently needed based on data suggesting they’re likely to confer clinical benefits.

It was the first time a therapy of this nature – a one-time treatment that delivers a working copy of a gene to make up for one that leads to disease – has been cleared under the accelerated approval framework, and the move came after emotional testimonials from families at an FDA advisory committee meeting last month.

Duchenne muscular dystrophy causes progressive muscle weakness that can rob kids of their ability to walk by the time they’re teenagers, and many don’t live well into their 30s. It affects an estimated one in 3,300 boys.

Sarepta said the therapy, called Elevidys, will cost $3.2 million per patient. It’s designed to be taken just once.

The group for whom the drug was approved, children ages 4 and 5, is about 6% of the population of people with Duchenne muscular dystrophy, according to Brian Abrahams, an analyst with Wall Street firm RBC Capital Markets. He had estimated that Sarepta would price the drug at $2.8 million per patient, which could bring in $2.1 billion in revenue from the initial group eligible for the drug.

While eye-popping, such a pricetag isn’t out of step with other one-time gene therapies, which have topped $3 million per patient in recent years. But Elevidys will become the second most expensive drug in the world, after the $3.5 million hemophilia treatment Hemgenix.

“Today’s approval addresses an urgent unmet medical need and is an important advancement in the treatment of Duchenne muscular dystrophy, a devastating condition with limited treatment options, that leads to a progressive deterioration of an individual’s health over time,” Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said in the agency’s news release. “The FDA remains committed to facilitating the development of innovative new therapies to reduce the impact of debilitating diseases and to improve outcomes and quality of life for those affected.”

Sarepta said in its own news release that the first results from its confirmatory trial of the drug are expected late this year.