Gene Therapy Helps Boys Walk Stronger 3 Years After Treatment

Three years after receiving a groundbreaking gene therapy, boys with Duchenne muscular dystrophy are walking, running, and standing stronger than doctors expected without treatment.

Elevidys, developed by Sarepta Therapeutics, delivered lasting physical improvements to 52 boys who received the one-time treatment in a clinical trial. When compared to 73 untreated boys with the same condition, the treated children scored an average of 4.39 points higher on motor function tests and could stand up from lying down six seconds faster.

Duchenne muscular dystrophy is a genetic condition that prevents the body from making dystrophin, a protein that keeps muscle cells intact. Without it, boys with the disease experience progressive muscle weakness that typically accelerates around age 9. Most lose the ability to walk in their early teens.

Elevidys works by delivering a gene that produces a shortened but functional version of dystrophin. The therapy is currently approved in the U.S. for patients ages 4 and older who can still walk.

The Bright Side

What makes these results particularly meaningful is the timing. The treated boys are now around 9 years old, the exact age when Duchenne typically begins stealing mobility and independence at a faster pace. Instead of declining, these children are maintaining and even improving their physical abilities.

Dr. Crystal Proud, a pediatric neurologist who worked on the study, sees the impact firsthand. "The results reflect what I see in clinical practice: helping boys perform everyday movements, such as standing, walking and running with greater strength and speed than what we expect as Duchenne progresses without treatment," she said.

The gap between treated and untreated patients has grown wider over time, suggesting Elevidys may genuinely slow disease progression rather than just provide temporary benefits. For families who have watched their children lose strength month by month, the stability alone represents a profound victory.

Sarepta emphasized that this marks the first gene therapy for Duchenne to demonstrate such dramatic changes in disease trajectory over multiple years. The company continues testing ways to make the treatment even safer, including adding immune-suppressing medications to reduce potential liver inflammation.

For boys with Duchenne and their families, these results transform what once seemed inevitable into something that might be changeable.