Experimental drug helps those with muscular dystrophy to walk

An experimental drug appears to preserve and possibly even improve the ability of boys with Duchenne muscular dystrophy to walk, according to the results of a clinical trial announced Wednesday, raising hopes that the first effective treatment for the disease might be on the horizon.

Boys with the disease who received the highest dose of the drug had a slightly improved ability to walk after 48 weeks of treatment, the drug's developer, Sarepta Therapeutics, announced. By contrast, the boys who received a placebo suffered a sharp decline in how well they could walk.

The drug, called eteplirsen, also appeared to restore levels of the key protein that muscular-dystrophy patients lack to about half of normal levels, Sarepta said.

There are many caveats. The trial had only 12 patients, with four patients receiving the top dose and four the placebo, and the data has not been published or reviewed by experts. It is also unclear how long the effects of the drug will last or whether safety issues would arise with longer treatment.

Even if it does work, the drug would be appropriate for only about 15 percent of patients with the disease, those with the particular genetic mutation the drug is designed to counteract. However, a similar technological approach might work for some other mutations.

Duchenne, which affects about 15,000 Americans, mainly boys and young men, is the most severe common form of muscular dystrophy, a disease made more prominent by years of Jerry Lewis telethons. Because of genetic mutations, people with the disease make barely any dystrophin, a protein necessary for muscles to function. Boys with Duchenne typically lose the ability to walk as teenagers and die by age 30.

While prednisone, a steroid, can slow progression of the disease somewhat, it also can cause side effects such as weight gain and bone weakening. Eteplirsen, which Sarepta says has shown no side effects, is vying with a similar drug being developed by GlaxoSmithKline to become the first drug that works by directly countering the mutation that causes the disease.

Enthusiasm for eteplirsen among patients and investors has been growing since July, when Sarepta announced how well patients could walk after 36 weeks of treatment. Sarepta's stock has quadrupled since then.

Christopher Garabedian, chief executive of Sarepta, said that while he expected the drug to slow the decline in walking ability as it had done at the 36-week point the fact that it improved walking ability was "beyond expectations."

Garabedian suggested in an interview that Sarepta would ask the Food and Drug Administration to approve eteplirsen based on the results of this small trial, rather than require it to do the customary large Phase 3 trial, which could delay approval until 2015.

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Experimental drug helps those with muscular dystrophy to walk