Genethon, released positive long-term efficacy data revealing three Duchene muscular dystrophy patients showed significant motor function gain as compared to untreated patients, and experienced significant and sustained reductions in creatine phosphokinase (CPK), a biomarker of muscle damage, two years after receiving an injection of Genethon’s low dose micro-dystrophin gene therapy (GNT0004).
At the micro-dystrophin dose of 3×10¹³ vg/kg the following was observed two years after injection:
- A significant gain in motor function as measured by a 34-point clinical assessment scale (NSAA): +5.8 points at 18 months compared to a cohort of untreated patients from the natural history study conducted in parallel (matched by propensity score). A gain significantly greater than the minimum difference is considered clinically relevant (>2.5 points).
- Clinical benefit at 18 months, maintained at 2 years, on functional parameters via timed tests, key indicators for ambulatory patients: -6.98s to get up from the floor and walking speed over 10 meters of +0.67 m/s (comparison similar to that of the NSAA score).
- A significant and sustained reduction in CPK levels by an average of 75% at 18 months and 61% at 2 years (compared to the patients’ baseline condition before treatment), reflecting a lasting effect on cell membrane stability.
- A slowdown in disease progression with a difference of more than 7% in muscle fat fraction (a marker of disease progression), observed by quantitative MRI, compared to a cohort of untreated patients from the natural history study.
- No serious side effects, confirming the safety of the product.
These results also were presented at the World Muscular Society’s WMS2025 October 7 – 11 in Vienna, Austria.
“These patients were treated in the dose escalation portion of our Phase 1/2/3 European trial and we are excited to present these positive long-term efficacy findings as we begin the Phase 3 pivotal trial, which is under way with the first patients included in France,” said Genethon CEO Frederic Revah. “The therapeutic 3×10¹³ vg/kg dose administered to the three patients is lower than other DMD gene therapies and is the dose being used the Phase 3 trial, which will enroll 64 boys, ages 6 to 10, who have retained their ability to walk.”
Read More: Potential Upcoming New Gene Therapies for Duchenne Muscular Dystrophy
