Sarepta Rises on Muscular Dystrophy Results: Boston Mover

Sarepta Therapeutics Inc. tripled in trading after its drug for Duchenne muscular dystrophy helped patients walk farther in a study and restored a key protein lacking in some of those with the disease.

Sarepta surged 200 percent to $44.93 at the close in New York, its biggest increase since 1997, after the Cambridge, Massachusetts-based biotechnology company said its experimental drug eteplirsen met the primary goal of the mid-stage study.

Patients who took 50 milligrams of eteplirsen once a week for 48 weeks could walk 89 meters (292 feet) farther during a six-minute test than those who took a placebo for 24 weeks and the drug for 24 weeks, Sarepta said today in a statement. The medicine may offer new promise against a disease in which current therapy only extends life and make it easier, rather than reverses the effects.

“With this study the boys actually got stronger, a pretty impressive result,” said Valerie Cwik, interim president of the Muscular Dystrophy Association in Tucson, Arizona.

Eteplirsen repairs a gene mutation in about 13 percent of Duchenne muscular dystrophy patients, helping them produce a missing protein and regain strength, Sarepta said in its statement.

$100,000 Help

Current therapy includes prednisone, a corticosteroid that can have the added side effect of weight gain, Cwik said. The association gave $100,000 to assist families who participated in Sarepta’s study with travel, she said.

Kimberly Lee, an analyst with ThinkEquity Partners in San Francisco, and Edward Tenthoff, an analyst with Piper Jaffray & Co., in New York, said Sarepta may file for approval based on the early results on the condition the company proves full benefit of the drug once it’s on the market, a process known as accelerated approval.

Tenthoff said he expected early approval, while Lee said eteplirsen will have to go through the normal approval process that will require another larger trial. The drug may reach peak annual sales of $600 million, Tenthoff estimated.

The trial studied four patients who received 50 milligrams of eteplirsen for 48 weeks and four patients who took the placebo first.

First-Ever Opportunities

The results “may lead to first-ever opportunities to target serious and life-threatening rare conditions at the origin of disease,” said Sarepta Chief Executive Officer Chris Garabedian in the statement.

Sarepta’s eteplirsen is made by manipulating RNA, or ribonucleic acid, which controls protein synthesis. RNA-based therapeutics can attack diseases by turning targeted proteins on or off, according to Sarepta.

The study results “signify the promise and tremendous potential of our RNA-based technology to impact and modulate disease at the genetic level,” Garabedian said.

Symptoms for Duchenne muscular dystrophy, which usually appears in boys before age 6, include loss of muscle tissue in the legs and pelvis and eventually throughout the body, according to the National Institutes of Health. Duchenne also causes learning difficulties, muscle weakness and mental retardation. The ability to walk may be lost by age 12.

Patients who took a 30 milligram-dose of eteplirsen didn’t experience a statistically significant benefit over those who began treatment on placebo. There were no adverse events.

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