Forelimb treatment in a large cohort of dystrophic dogs supports delivery of a recombinant AAV for exon skipping in Duchenne patients

Mol Ther. 2014 Nov;22(11):1923-35. doi: 10.1038/mt.2014.151. Epub 2014 Aug 4.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cohort Studies
  • Dependovirus / genetics*
  • Disease Models, Animal
  • Dogs
  • Dose-Response Relationship, Drug
  • Dystrophin / genetics*
  • Exons
  • Forelimb / physiopathology*
  • Genetic Therapy
  • Genetic Vectors / administration & dosage
  • Humans
  • Infusions, Intravenous
  • Muscular Dystrophy, Duchenne / genetics
  • Muscular Dystrophy, Duchenne / physiopathology
  • Muscular Dystrophy, Duchenne / therapy*
  • RNA, Small Nuclear / genetics*
  • RNA, Small Nuclear / metabolism


  • Dystrophin
  • RNA, Small Nuclear
  • U7 small nuclear RNA