Gene therapy hope for muscle disorder

US researchers have begun a clinical trial to test a new gene therapy treatment for Duchenne muscular dystrophy (DMD), an inherited muscle-wasting disorder. The team, based at the Columbus Children's Hospital in Ohio, will test the safety and effectiveness of gene injections in six affected boys aged 8-12 years. Scientists at the Universities of North Carolina and Pittsburgh have spent 20 years developing the new treatment, which involves the use of a 'miniaturised' version of a gene that makes a crucial muscle protein.    

DMD is a serious genetic disorder that mainly affects boys. It is caused by mutations in the dystrophin gene, which makes one of a cluster of proteins that hold muscle cells together. Although the main symptom of the condition is progressive wasting of the muscles used for movement, the heart is also often affected. Efforts to develop a gene therapy treatment for DMD have been hampered by the unusually large size of the dystrophin gene, which is too big to deliver using standard methods. The new trial will use a trimmed-down version of the gene, called 'minidystrophin', which will be delivered using a modified adeno-associated virus (AAV).

The six boys will receive injections of the replacement gene into the bicep of one arm, and injections of a placebo into the other. After six weeks, the researchers will analyse samples of muscle and test the strength of both arm muscles, to see if the treatment - dubbed Biostrophin - makes a difference. The scientists, who formed the company Asklepio BioPharmacuetical (AskBio) to make and test the treatment, obtained approval to proceed with the trial from the US Food and Drug Administration (FDA) on 3 March. 'After years of encouraging pre-clinical results, I'm excited that AskBio will help bring this promising new therapy into the clinic', said team leader Jude Samulski.

The first boy to receive the treatment was eight-year-old Andrew Kilbarger, who was given three injections in each arm on 29 March. His parents hope that by taking part in the research, funded by the US Muscular Dystrophy Association, they might one day improve the outlook for other boys affected by the disease. 'We don't hit the moon with our first shot', said Andrew's mother, Julie Kilbarger, adding 'somebody has to step up. Somebody has to be the first one'. The scientists hope that eventually, it will be possible to inject the gene treatment at higher doses, and into the patients' legs. 'Then, we really could improve the quality of life', said neurologist Jerry Mendell, who is running the trial.