rAAVrh74.MCK.micro-dystrophine administration in 4 boys with DMD results in dystrophin production and has a functional effect

The results of a phase I / II clinical trial still underway in the USA which evaluates the safety and efficacy of rAAVrh74.MCK.micro-dystrophin (SRP-9001), a gene therapy product developed by Sarepta Therapeutics, were published in the journal JAMA Neurology on June 15, 2020.

This trial has so far included 4 boys aged 4 to 6 years (mean age: 4.8 years at inclusion) with Duchenne muscular dystrophy. The molecule was given to them all at once by intravenous infusion. Safety, pharmacokinetic and efficacy measurements were taken over time and 12 months after treatment.

Targeted dystrophin production and functional improvement

  • Three months after treatment, 81.2% of muscle fibers (on average) produce dystrophin. This proportion reaches 95% of purely muscle fibers,i.e. muscle fibers which have not become fatty or fibrotic tissue.
  • Dystrophin is well located under the membrane for 96% of the positive fibers. Beta-sarcoglycans are present in these cells, testifying to the restoration of the DAP complex.
  • One year after administration of the treatment, the treated children improved their motor skills. The performance scores measured with the NSAA scale for the 4 patients increased by an average of 5.5 points (range 2 to 8).
  • The level of creatine kinase in the blood has dropped by 67.29% on average, a sign that the muscle is getting better.
  • rAAVrh74.MCK.micro-dystrophin is well tolerated with no serious adverse effects.

The phase I / II trial is ongoing through 2021 and another phase II trial of rAAVrh74.MCK.micro-dystrophin including older children, aged 4 to 7 years, is being recruited.


Assessment of Systemic Delivery of rAAVrh74.MHCK7.micro-dystrophin in Children With Duchenne Muscular Dystrophy. A Nonrandomized Controlled Trial. Jerry R. Mendell, Zarife Sahenk, Lehman K, et al. JAMA Neurol. 2020 Jun 15 : e201484