Funding outcome

Duchenne muscular dystrophy (DMD), the most common and lethal genetic disorder in childhood, is caused by mutations in a gene called dystrophin or DMD. Approximately 1 in every 3,500-5,000 boys are born with DMD regardless of ethnic background. Mean age of death is around 25-30 years. My group is working towards the goal of finding a cure for DMD. A most promising therapeutic strategy to treat DMD is a molecular therapy called exon skipping. Exon skipping employs a short DNA-like molecule that acts like a stitch. This 'DNA stitch' can facilitate the production of short but functional proteins. Currently, several phase II and Ill international clinical trials are being conducted based on our previous studies, and the FDA approved the first drug of this class of 'DNA-stitch' called eteplirsen for the treatment of DMD in late 2016. However, two challenges still remain unsolved. First, currently approved drug is only applicable to approximately 10% of DMD patients. Second, the clinical trials showed no significant improvement in patients, thus the approval is only conditional until further confirmation study is completed. Here, we will take this therapeutic a step further, by experimenting with a cocktail of DNA-like molecules. The overall objective of our research proposal is to expand the applicability of exon skipping therapy with a cocktail of DNA-like molecules targeting multiple parts of the mutated gene. This strategy (cocktail approach) is applicable to 63% of DMD patients with a deletion mutation in the gene. In addition, this specific deletion mutation in the DMD gene produced by the cocktail is known to be associated with remarkably mild or often almost no symptoms. We will employ muscle cell lines obtained from DMD patients as well as a humanized DMD mouse model, which harbors the human DMD gene instead of the mouse Dmd gene. We will quantitatively measure the efficacy by methods such as RT-PCR (to measure the corrected RNA levels), Western Blotting (to measure the protein restored), and immunocytochemistry (to visualize the restored protein in muscle cells), and select the best oligonucleotides to rescue dystrophin. The results of this study can have profound effects on current drug trials. By administrating a cocktail of antisense oligonucleotides, significant muscle function can be restored. Our goal is to achieve 10-15% of dystrophin protein levels, which will significantly decrease the symptoms of the lethal disorder.