Walking Easier with Muscular Dystrophy

Duchenne muscular dystrophy may get new treatment

(RxWiki News) Tasks as simple as walking can be difficult for patients with Duchenne muscular dystrophy. The disorder causes the body to produce too little dystrophin, a necessary protein for muscles. Without this protein, muscles continue to worsen.

A new study showed that the medication eteplirsen could help the body make more dystrophin. This study also showed that patients who received eteplirsen were able to walk better than the patients who received a placebo (fake medication).

Currently, there is no cure for Duchenne muscular dystrophy. Steroids and physical therapy have been shown to be somewhat helpful to slow muscle weakening.

Eteplirsen is not currently available, but researchers expect the medication to be reviewed by the FDA for approval in early 2014.

"Ask your doctor about ways to help manage Duchenne muscular dystrophy."

Jerry Mendell, MD, director of the Centers for Gene Therapy and Muscular Dystrophy at Nationwide Children's Hospital, and colleagues conducted this study to find out if eteplirsen causes the body to create more dystrophin — the missing protein in Duchenne muscular dystrophy patients.

Duchenne muscular dystrophy is a disorder that causes muscle loss.

The authors of this study said that previous studies had found that the medication eteplirsen caused dystrophin to be produced in Duchenne muscular dystrophy patients, relieving the muscle loss caused by the disease.

Currently, there is no known cure for Duchenne muscular dystrophy or ways to reverse the damage caused by the disease. There are therapies, such as steroid injections and physical therapy, which can slow the disease from getting worse.

Eteplirsen is a once-a-week medication, also called AVI-4658. It's currently in the experimental phase. The US Food and Drug Administration is expected to decide whether to approve eteplirsen in 2014.

From this study, the researchers also wanted to see if patients receiving eteplirsen would be able to walk better than they did before taking the medication.

The researchers identified 12 boys from 7 to 13 years of age with Duchenne muscular dystrophy. Each boy was randomly assigned to receive either a placebo, 30 milligrams of eteplirsen or 50 milligrams of eteplirsen. The study lasted 24 weeks, and at the end, the patients who had received the placebo also received eteplirsen.

The patients have continued receiving eteplirsen in an “open label” long-term extension study, meaning the researchers now know which medications the boys are receiving and will follow them through 84 weeks.

The researchers took muscle biopsies (sample of tissue) to test dystrophin levels before the study began, then again 48 weeks later. At 48 weeks, the 30-milligram patients had increased, on average, to 52 percent of normal dystrophin levels. The 50-milligram patients also had increased dystrophin levels. On average, they had 43 percent of normal dystrophin levels.

The patients who took the placebo showed no increase in dystrophin levels. When the placebo patients received eteplirsen later in the studies, their dystrophin levels increased as well.

The researchers also tested the patients' ability to walk with a six-minute walk test at 48 weeks. They found that the patients who received eteplirsen were able to walk 67.3 meters further than the placebo patients. The patients receiving both the 30- and 50-milligram doses of eteplirsen had more stability while walking.

The authors noted that it was the length of time eteplirsen was taken that influenced the level of dystrophin, not the dose of medication.

The study was double-blind, meaning neither the patients nor researchers knew what kind of medication the patients were receiving. The authors stated that there were no bad reactions to the medication. No one was hospitalized or stopped taking the medication due to side effects.

This study was published online August 1 in the Annals of Neurology. It was funded by Sarepta Therapeutics, a pharmacology company which hopes to produce the medication if it is FDA-approved.

Review Date: 
August 9, 2013