This week, Sarepta Therapeutics announced encouraging preliminary results from a phase 1/2a gene therapy trial designed to assess the investigational drug AAVrh74.MHCK7.micro-Dystrophin in boys with Duchenne muscular dystrophy (DMD).
After 90 days in the trial, the first three participants all showed robust expression of micro-dystrophin — a shortened version of the protein that is absent in the muscle of those with DMD. Participants also showed a decrease in levels of serum creatine kinase (CK), an enzyme biomarker strongly associated with muscle damage caused by DMD.
Additional studies, conducted for a longer period of time and with a larger number of trial participants, will be needed to determine whether AAVrh74.MHCK7.micro-Dystrophin could be a safe and effective therapy for treatment of Duchenne.
Delivering a replacement dystrophin gene
Principal investigator Jerry Mendell, M.D., of Columbus, Ohio’s Nationwide Children’s Hospital, in collaboration with Louise Rodino-Klapac, Ph.D., developed AAVrh74.MHCK7 specifically for DMD. The drug is designed to address the genetic cause of the disease via the delivery of highly miniaturized “micro-dystrophin” replacement genes that enable production of a functional protein to substitute for the dystrophin missing in people with DMD.
Encased in an adeno-associated virus (AAV) vector, or delivery vehicle, micro-dystrophin genes are administered systemically to the body via intravenous infusion. Researchers believe the AAV used in this study should allow delivery of micro-dystrophin genes to skeletal muscle, cardiac muscle and the diaphragm.
An exciting time for gene therapy research
“I have been waiting my entire 49-year career to find a therapy that dramatically reduces CK levels and creates significant levels of dystrophin,” Mendell says. “Although the data are early and preliminary, these results, if they persist and are confirmed in additional patients, will represent an unprecedented advancement in the treatment of DMD.”
MDA President and CEO Lynn O’Connor Vos agrees.
“The Muscular Dystrophy Association is very encouraged by Sarepta’s interim results from the micro-dystrophin gene therapy study,” she says. “The findings look promising, and we believe that important progress is being made. This is an exciting time in clinical development for neuromuscular disease and we look forward to continued advancement of gene therapies for Duchenne and related disorders.”
Eligibility requirements for participation
Sarepta Therapeutics expects to enroll additional participants in the study. Initial details on eligibility criteria include:
- Participants must be male and between the ages of 3 months to 7 years old.
- Participants must have a genetic test, and their mutation must be between exons 18 to 58.
- All participants must be below a pre-determined threshold for antibodies against AAV; this will be tested as part of the screening process. Screening and selection will be conducted by investigators at the clinical trial sites.