The shares of a Cambridge biotechnology firm fell sharply Thursday despite the release of clinical data that showed its treatment for a severe form of muscular dystrophy slowed the effects of the fatal, muscle-wasting disease.
While the company, Sarepta Therapeutics, hailed the results as positive, they apparently were not positive enough for investors, who dumped the stock when markets opened. Chad Messer, an analyst with Needham & Co. LLC, a New York investment firm, said he was puzzled by the market reaction.
He said the results of Sarepta’s three-year study showed the company is on the right track. “This is an unwarranted sale . . . of shares at a lower price than merits,” Messer said.
Sarepta’s stock lost about 13 percent Thursday, closing at $22.54.
Sarepta said that the results are good enough to seek approval from the Food and Drug Administration later this year with the goal of selling the drug, called eteplirsen, in 2015, to treat the disease known as Duchenne muscular dystrophy. If approved, it would be Sarepta’s first commercial drug.
“We’re very encouraged by this data,” Sarepta’s chief executive, Chris Garabedian, said in an interview. “This is more evidence that the FDA can look at to positively review eteplirsen’s treatment benefits.”
Duchenne muscular dystrophy occurs in about 1 of every 3,500 boys, destroying muscle function and quality of life over time. The disease moves swiftly, robbing most of those afflicted of the ability to walk by their teen years and damaging their respiratory muscles. Duchenne patients typically do not live past their 20s
Sarepta has tried its experimental drug in a dozen boys over about three years. Lung function of the boys, who are, on average 12 years old, has not deteriorated as it does for most with Duchenne. Some published reports, however, suggested that data showed the boys ability to walk declined more than expected.
Of the 12 in the trial, 10 are still walking, while the other two lost that ability early in the studies. Sarepta said their treatment slowed or stabilized the progression of the disease.
“We now have three years of data that shows something that’s very different from what would be expected in the natural progression of this disease,” Garabedian said.
Sarepta’s technology uses RNA, genetic material that among other functions directs the production of proteins in the body. Sarepta’s drug is designed to change how RNA molecules are processed in muscle cells to boost production of a protein called dystrophin, which people with Duchenne are missing. The company is moving quickly to expand trials.
Jenn McNary of Pembroke said the drug has been life-changing for her 12-year-old son, Max Leclaire, who is part of the original study. Before he started using the drug, Max had trouble walking and sometimes used a wheelchair.
“Eteplirsen has changed Max’s quality of life in amazing ways,” McNary said. “He is able to pedal a simple bicycle, be on foot for entire days [at] the zoo, the airport, hospital, all places where he used to require a wheelchair prior to being in the trial.”
None of the boys on eteplirsen experienced adverse events or had to be hospitalized because of reactions to the drug, Sarepta said. The drug is given in weekly injections.
Sarepta was founded on the West Coast in 1980 and went public in 1997. This year, Sarepta moved its headquarters from Seattle to Cambridge’s Kendall Square, where it employs about 90.
A rival biotech company, Prosensa Holding N.V. of the Netherlands, is developing a similar drug for Duchenne patients called drisapersen and also plans to file for approval with the FDA this year.
Both Sarepta and Prosensa’s drugs are designed for about 13 percent of Duchenne patients who have a certain genetic mutation. The companies also are developing treatments for other forms of Duchenne.
Akashi Therapeutics, another Cambridge company focused on Duchenne, is working on an oral medication to reduce scar tissue and inflammation. Akashi said last week that according to early data, its drug appears to be safe.Deirdre Fernandes of the Globe staff contributed to this report. Priyanka Dayal McCluskey can be reached at firstname.lastname@example.org. Follow her on Twitter @priyanka_dayal.