New DMD treatment shows promise in early trials

An experimental treatment for boys with the inherited muscle wasting disease Duchene Muscular Dystrophy (DMD) has showed promise in human safety trials, according to a study published in the New England Journal of Medicine. In the first ever trial on humans, the new drug was shown to help DMD patients produce dystrophin - an essential muscle protein missing in DMD patients.

DMD is a muscle-wasting disease that causes a steady deterioration of muscles and often results in death before the age of 30. The condition, which is usually inherited and incurable, affects one in 3500 male newborn boys and is caused by a fault in the gene that encodes the body's instructions for making dystrophin.

The treatment, developed by the Dutch pharmaceutical company Prosensa, uses an 'antisense-RNA' - a chemical relative of DNA - as a 'molecular patch' to fix the genetic defect which causes DMD. In the trial, four DMD boys aged 10-13 received an injection of the drug - called PRO051 - into a leg muscle and four weeks later low levels of dystrophin were measured in all four boys.

Although not enough dystrophin was produced to reduce the symptoms of DMD in the boys, the researchers have taken the results as 'proof of principal' - an indication the treatment is safe and could potentially be effective if administered in larger doses throughout the body.

Prof Gert-Jan van Ommen, together with his colleagues Dr Judith van Deutekom and Dr Jan Verschuuren, responsible for the research, reported that the next step would be to carry out a 'systemic' trial where the drug was injected under the skin of the patients, delivering the drug to muscles all over the body. 'The robust expression in all four patients with different mutations after a single injection points to a solid effect. The results form an excellent starting point for systemic treatment trials', they said in a statement.

DMD is caused by a variety of different mutations and so the PRO051 drug will only be suitable for around 13 per cent of all DMD patients explained Prof van Ommen. This means that if the technique works, it would probably take 10 different antisense drugs to treat about half of all children with Duchenne's, he said. Experts have warned that, if effective, the drug will be expensive - costing perhaps more than £100,000 - and will need to be administered throughout the patient's life to be effective.