Forelimb Treatment in a Large Cohort of Dystrophic Dogs Supports Delivery of a Recombinant AAV for Exon Skipping in Duchenne Patients
Authors: Caroline Le Guiner, Marie Montus, Laurent Servais, Yan Cherel, Virginie Francois, Jean-Laurent Thibaud, Claire Wary, Béatrice Matot, Thibaut Larcher, Lydie Guigand, Maeva Dutilleul, Claire Domenger, Marine Allais, Maud Beuvin, Amélie Moraux, Johanne Le Duff, Marie Devaux, Nicolas Jaulin, Mickaël Guilbaud, Virginie Latournerie, Philippe Veron, Sylvie Boutin, Christian Leborgne, Diana Desgue, Jack-Yves Deschamps, Sophie Moullec, Yves Fromes, Adeline Vulin, Richard H Smith, Nicolas Laroudie, Frédéric Barnay-Toutain, Christel Rivière, Stéphanie Bucher, Thanh-Hoa Le, Nicolas Delaunay, Mehdi Gasmi, Robert M Kotin, Gisèle Bonne, Oumeya Adjali, Carole Masurier, Jean-Yves Hogrel, Pierre Carlier, Philippe Moullier, Thomas Voit
Journal: Molecular Therapy (2014)

Duchenne muscular dystrophy (DMD) is a severe muscle-wasting disorder caused by mutations in the dystrophin gene, without curative treatment yet available. Our study provides, for the first time, the overall safety profile and therapeutic dose of a recombinant adeno-associated virus vector, serotype 8 (rAAV8) carrying a modified U7snRNA sequence promoting exon skipping to restore a functional in-frame dystrophin transcript, and injected by locoregional transvenous perfusion of the forelimb. Eighteen Golden Retriever Muscular Dystrophy (GRMD) dogs were exposed to increasing doses of GMP-manufactured vector. Treatment was well tolerated in all, and no acute nor delayed adverse effect, including systemic and immune toxicity was detected. There was a dose relationship for the amount of exon skipping with up to 80% of myofibers expressing dystrophin at the highest dose. Similarly, histological, nuclear magnetic resonance pathological indices and strength improvement responded in a dose-dependent manner. The systematic comparison of effects using different independent methods, allowed to define a minimum threshold of dystrophin expressing fibers (>33% for structural measures and >40% for strength) under which there was no clear-cut therapeutic effect. Altogether, these results support the concept of a phase 1/2 trial of locoregional delivery into upper limbs of nonambulatory DMD patients. Duchenne muscular dystrophy (DMD) is a severe muscle-wasting disorder caused by mutations in the dystrophin gene, without curative treatment yet available. Our study provides, for the first time, the overall safety profile and therapeutic dose of a recombinant adeno-associated virus vector, serotype 8 (rAAV8) carrying a modified U7snRNA sequence promoting exon skipping to restore a functional in-frame dystrophin transcript, and injected by locoregional transvenous perfusion of the forelimb. Eighteen Golden Retriever Muscular Dystrophy (GRMD) dogs were exposed to increasing doses of GMP-manufactured vector. Treatment was well tolerated in all, and no acute nor delayed adverse effect, including systemic and immune toxicity was detected. There was a dose relationship for the amount of exon skipping with up to 80% of myofibers expressing dystrophin at the highest dose. Similarly, histological, nuclear magnetic resonance pathological indices and strength improvement responded in a dose-dependent manner. The systematic comparison of effects using different independent methods, allowed to define a minimum threshold of dystrophin expressing fibers (>33% for structural measures and >40% for strength) under which there was no clear-cut therapeutic effect. Altogether, these results support the concept of a phase 1/2 trial of locoregional delivery into upper limbs of nonambulatory DMD patients.