After three decades without bringing a drug to market, Sarepta Therapeutics Inc stands on the verge of a breakthrough with its treatment for a crippling genetic disorder that affects one in every 3,500 newborn boys. If U.S. regulators fast-track approval of its treatment for Duchenne muscular dystrophy, as some investors are betting, it would complete a remarkable turnaround for the company that began life as AVI Biopharma in Corvallis, Oregon, 33 years ago. Sarepta’s stock has more than doubled in value since October, when its drug, eteplirsen, yielded positive results in a mid-stage trial. The company has a market capitalization of $1.1 billion. Duchenne muscular dystrophy, or DMD, is classed as an orphan disease -- a condition affecting fewer than 200,000 people. More than a quarter of the 39 new medicines approved in the United States last year were designated for such diseases.
