Mixed results on therapy for muscular dystrophy

Sarepta Therapeutics said Monday that its gene therapy for Duchenne muscular dystrophy failed to improve muscle function compared to a placebo in a large clinical trial — likely a major disappointment for patients and doctors who have been desperately awaiting the treatment for years.

The company said all patients in the study improved and that secondary measurements indicated the drug was having an effect. Nevertheless, the results are likely to raise questions about whether the Food and Drug Administration will expand access to the medicine.

The FDA gave accelerated approval — a form of provisional clearance — to the one-time gene therapy, called Elevidys, in June but only for 4- and 5-yearolds. The 125-patient, placebocontrolled study was designed to confirm the benefit in those patients while also potentially providing a basis to expand that approval to older patients.

In the study, called Embark, patients given Elevidys improved 2.6 points on the North Star Ambulatory Assessment, a measure of muscle function, after one year. Patients given placebo improved 1.9 points. The difference was not statistically significant.

The study enrolled boys with Duchenne ages 4-7, an age range when patients often begin to decline and when it can be easiest to show a benefit.

Despite missing the study’s primary goal, Sarepta said it intends to ask the FDA for an update to broaden Elevidy’s approval to remove restrictions based on age or walking ability.

“The Embark results have met the standard for substantial evidence of effectiveness,” Sarepta CEO Doug Ingram said on a conference call. “The evidence is also clear that Elevidys benefits patients across the ages in the study.”

Alexander Fay, a pediatric neurologist at University of California-San Francisco, took a more cautious view of the results. One year, he said, is probably not enough to measure the effect of the treatment, which experts hope will help stabilize the disease or alter its long-term course.

In the absence of more data, he was uncertain it should be approved for patients over the age of 7, a group that may also experience more side effects because they require a larger dose.

“I don’t feel there’s enough to say we can extrapolate to those older boys, and everyone will experience a benefit without doing harm,” said Fay, who was not involved in the study.