The deadly saga of the controversial gene therapy Elevidys

In the days since, the company has acquiesced. But its reputation has already been hit. And the events have dealt a devastating blow to people desperate for treatments that might help them, their children, or other family members with DMD.

DMD is a rare genetic disorder that causes muscles to degenerate over time. It’s caused by a mutation in a gene that codes for a protein called dystrophin. That protein is essential for muscles—without it, muscles weaken and waste away. The disease mostly affects boys, and symptoms usually start in early childhood.

At first, affected children usually start to find it hard to jump or climb stairs. But as the disease progresses, other movements become difficult too. Eventually, the condition might affect the heart and lungs. The life expectancy of a person with DMD has recently improved, but it is still only around 30 or 40 years. There is no cure. It’s a devastating diagnosis.

Elevidys was designed to replace missing dystrophin with a shortened, engineered version of the protein. In June 2023, the FDA approved the therapy for eligible four- and five-year-olds. It came with a $3.2 million price tag.

The approval was celebrated by people affected by DMD, says Debra Miller, founder of CureDuchenne, an organization that funds research into the condition and offers support to those affected by it. "We've not had much in the way of meaningful therapies," she says. "The excitement was great."

But the approval was controversial. It came under an “accelerated approval” program that essentially lowers the bar of evidence for drugs designed to treat “serious or life-threatening diseases where there is an unmet medical need.”

Elevidys was approved because it appeared to increase levels of the engineered protein in patients’ muscles. But it had not been shown to improve patient outcomes: It had failed a randomized clinical trial.

The FDA approval was granted on the condition that Sarepta complete another clinical trial. The topline results of that trial were described in October 2023 and were published in detail a year later. Again, the drug failed to meet its “primary endpoint”—in other words, it didn’t work as well as hoped.