Sarepta Therapeutics Inc. (SRPT) experienced a bit of schadenfreude on Aug. 16 as a direct competitor stumbled badly at the finish line.

Competitor GlaxoSmithKline plc (GSK) had been neck-and-neck with Serepta in the race to develop a breakthrough muscle disorder drug to treat Duchenne Muscular Dystrophy. Both drugs were far ahead of the pack in the development process.

That is, until Baird analyst Brian Skorney reported that Glaxo’s drug, drisapersen, has encountered major stumbling blocks on several fronts that could significantly hamper development. Skorney cited clinical, regulatory, and commercials issues with the drug. Most importantly, the drug did not seem to effectively treat symptoms of the disease at the targeted dose.

Serepta’s drug, eteplirsen, so far has seemed to be effective at treating symptoms of Duchenne. Clinical trials have taken place in the UK. On Aug. 7 the company released promising clinical trial information, which will form the basis of their application for US FDA approval in early 2014.

Duchenne is a severely debilitating form of muscular dystrophy. The recessive muscular degenerative disorder affects approximately 1 in 3,600 boys, and life expectancy for sufferers is usually around 25. A drug from either company would be the first on the American market designed to treat the disorder.

The London-based GlaxoSmithKline , which is the fourth largest pharmaceutical company in the world, shrugged off the setback. Their stock is up .33 percent to hit $51.70 a share.

Serepta is up 6.77 percent to hit $34.21 a share.