Genethon Receives Regulatory Approvals for Pivotal Phase 3 AAV Gene Therapy Trial for DMD in Europe

PARIS – (BUSINESS WIRE) – Genethon, a global pioneer and leader in AAV gene therapy research and development for rare genetic diseases, today announced it has received approvals from the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) and the European Medicines Agency (EMA) to commence pivotal Phase 3 clinical trials for its AAV gene therapy, GNT0004, for Duchenne muscular dystrophy (DMD) in France and the UK.

“We are delighted to be able to continue these trials and are determined to bring GNT0004 to market for young patients and their families who are waiting for a therapeutic solution,” said Frederic Revah, Genethon CEO. “This marks a decisive step forward for our AAV gene therapy program for DMD, which began in 2021 and has demonstrated extremely promising results in the first children treated in the Phase 1/2 portion of our Phase 1/2/3 study.”

Dr. Revah emphasized the unique aspects of GNT0004, adding, “In addition to the very positive results in patients treated in the early phases, one of the strengths of our product is the dose selected for the pivotal phase, which is lower than those used in other AAV gene therapy trials for DMD. Approvals of our Phase 3 trials reflect the regulatory authorities’ confidence in GNT0004 as well as the work accomplished by our teams.”

The European Phase 3 authorizations are based on compelling results from earlier Phase 1/2 studies. These studies showed GNT0004 to be well-tolerated and demonstrated efficacy through microdystrophin expression, a reduction in creatine phosphokinase (CPK — a key marker of muscle damage), and improvements in motor function. Patients exhibited prolonged improvement or stabilization of motor functions and a significant, persistent reduction in CPK levels.

The double-blind Phase 3 trials are scheduled to begin in August and September in the UK and France. Participants will receive a single intravenous injection of GNT0004. The AAV therapy contains an optimized hMD1 transgene, a shortened but functional version of the gene encoding dystrophin (3×10¹³ vg/kg microdystrophin), delivered via an AAV8 vector. This AAV vector is specifically designed to express in muscle tissue and the heart due to a Spc5-12 promoter sequence, and is associated with transient immunological prophylactic treatment. A total of 64 boys aged 6 to 10 with DMD who retain their walking ability will be enrolled in the study.

About Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a rare, progressive genetic disease that primarily affects boys (approximately 1 in 5,000). It is caused by abnormalities in the gene responsible for producing dystrophin, a crucial structural protein for muscle fiber stability and metabolism. The absence of dystrophin leads to progressive degeneration of skeletal and cardiac muscles, resulting in loss of walking and respiratory capacity, progressive heart failure, and often leads to death between the ages of 20 and 40.