The first gene therapy that can treat Duchenne muscular dystrophy (DMD) has been approved by the U.S. Food and Drug Administration; it will be marketed as Elevidys (delandistrogene moxeparvovec-rokl) by Sarepta Therapeutics Inc. Children aged four to five with the disorder and confirmed gene mutations will be eligible to receive the one-time treatment if insurers approve, as the cost is $3.2 million per patient.
DMD is caused by mutations in a gene called dystrophin, which results in a serious lack of functional dystrophin protein. The gene therapy works by sending a gene that can produce a shortened version of the dystrophin protein to patients; the company has termed it Elevidys micro-dystrophin.
Two clinical trials showed that a micro-dystrophin protein was expressed in recipients of the treatment. However, this approach has only been shown to benefit some very young patients, and did not seem to improve the condition of affected kids who were a bit older.
The company will now undergo a Phase 3, double-blinded trial to confirm that it will can improve motor function in kids who carry mutations in the dystrophin gene. If it does not produce positive results in that trial, the FDA can revoke the approval.
Like any gene therapy, this trial will come with risks. There were adverse events in fewer than five percent of people who were exposed to the drug, but some did arise. Elevidys has caused disruptions in liver function in a few recipients, so anyone who is treated with the drug will also have to be monitored very closely for any sign of liver problems, and treatment will have to be carefully considered for those with pre-existing liver issues. Muscle inflammation and severe muscle weakness also occurred in some people who were treated with Elevidys.
Children with DMD are urgently in need of new treatments, so the FDA thought the potential benefits outweigh the risks. This drug was also approved through the FDA's fast track route. This mode of approval is meant to quickly bring potential treatments for severe disorders to patients. But some have criticized this method, and drugmakers have often failed to show that their fast-tracked drugs are actually helping people.
DMD is a serious disorder that often kills patients by the time they reach their twenties, so for many patients and families, it will be worth testing the drug to see if it helps.
"The approval of Elevidys is a watershed moment for the treatment of Duchenne. Elevidys is the first and only gene therapy approved for Duchenne, and this approval brings us closer to our goal of bringing forward a treatment that provides the potential to alter the trajectory of this degenerative disease," said Sarepta President and CEO Doug Ingram.
Sources: FDA, AP, Serepta Therapeutics
