Genethon Cleared to Launch French Trial Testing GNT0004 Gene Therapy for DMD

The French National Agency for Medicines and Health Products Safety has cleared Généthon to begin a clinical trial testing the safety and efficacy of GNT0004, a potential gene therapy for Duchenne muscular dystrophy (DMD), in France.

“From translational research to clinical application, Généthon has supported this candidate drug, which is the concrete result of years of cutting-edge research conducted at our laboratory,” Frédéric Revah, CEO of Généthon, said in a press release. “This trial for this devastating disease, marks a new decisive stage for Genethon.”

Duchenne is caused by a genetic mutation in the DMD gene, which gives the instructions necessary to produce a protein called dystrophin that provides structural support and protection for muscle fibers. In people with DMD, a mutation in this gene prevents the body from making this protein, leaving muscles open to potential damage when contracting and relaxing.

GNT0004 uses a harmless adeno-associated viral vector to carry instructions to make a shortened form of dystrophin, called micro-dystrophin.

In order to introduce dystrophin into patients’ cells, the gene had to be made shorter. As the largest known human gene, full-length DMD cannot fit into viral vectors. Micro-dystrophin was invented as a way around this obstacle, by shortening the gene down to its minimal functional components.

Généthon partnered with Sarepta Therapeutics to further develop the micro-dystrophin-based gene therapy in preclinical and clinical studies.

A study carried out in dogs that naturally develop muscular dystrophy supported micro-dystrophin’s potential in treating DMD. The treated dogs showed greater muscle function and their overall symptoms stabilized for two years.

Généthon has already begun a pre-inclusion study at the trial sites to be used in France. It will help identify children eligible for the trial by following the disorder’s natural progression over three months to three years, among 100 ambulatory boys ages 5 to 9. The measures used in the study will define the clinical trial’s goals.

The company aims to expand the trial beyond France, planning further sites in the U.S., the U.K., and Israel.

The participating centers in France are in Strasbourg, Paris, Brest, Bordeaux, Lyon, Marseille, and Lille.

Sarepta has been developing another micro-dystrophin known as SRP-9001. A Phase 1/2 trial (NCT03375164) run by Sarepta at Nationwide Children’s Hospital demonstrated sustained safety and tolerability among boys with DMD. Over a follow-up period of more than two years, these participants showed no immune system activation, and an average seven-point increase from the study’s start in their North Star Ambulatory Assessment score, a rating scale assessing motor abilities in DMD children who can walk independently.