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Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Sarepta Therapeutics (NASDAQ:SRPT), a biopharmaceutical company that uses RNA-based therapeutics for the treatment of infectious diseases, shot higher by as much as 12% following disappointing news from one of its competitors in treating Duchenne muscular dystrophy, or DMD.

So what: According to an article published by Adam Feuerstein at TheStreet.com earlier today, GlaxoSmithKline (NYSE:GSK) disclosed safety data from its early stage trial of drisapersen, which showed that some patients had to be hospitalized because of kidney toxicity and low platelet counts. The news stands to benefit Sarepta, whose lead drug candidate is Eteplirsen in DMD and has demonstrated a tame adverse event profile through clinical trials.

Now what: Glaxo didn't offer any additional information about those patients who were hospitalized over the previous two years, but clearly this is another step in the right direction for Sarepta if its competitors are faltering. If you recall, Sarepta's Eteplirsen not only curbed progression of the disease, but actually improved walking distance over a six-minute period in trials -- a truly astonishing result should it hold up in further testing and translate over to the general DMD-suffering population. Sarepta is definitely a name you must have on your watchlist.

Craving more input? Start by adding Sarepta Therapeutics to your free and personalized Watchlist so you can keep up on the latest news with the company.

Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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