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Why Prosensa NV Shares Roared Higher

By Sean Williams – Jan 16, 2014 at 3:44PM

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Prosensa shares soar after it reported encouraging clinical findings for Duchenne muscular dystrophy drug drisapersen. Here's why investors might want to consider taking this "encouraging" news with a grain of salt.

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 Prosensa (NASDAQ: RNA), a clinical-stage developer of RNA-modulating therapeutic agents for genetic disorders, jumped as much as 50% after reporting additional clinical findings on drisapersen at the JPMorgan Healthcare Conference.

So what: According to Prosensa's press release, which corresponds with its earlier presentation time at the JPMorgan Healthcare Conference, further analysis from the aggregate data collected from its late-stage drisapersen trial to treat Duchenne muscular dystrophy suggest that earlier treatment of the disease, and therefore a longer duration of treatment, could delay progression of the disease. Prosensa intends to consult with clinical experts and regulators to determine if there is a path forward for drisapersen, which failed to meet its primary endpoint in a phase 3 trial in September.

Now what: Before you get too excited, my suggestion would be "Don't!" There are a lot of variables to work through here, including persuading the Food and Drug Administration that drisapersen has clinical benefits following a trial that demonstrated no benefits over the placebo, and the development of a drug that has no partner, as GlaxoSmithKline (GSK 1.27%) announced that it would be ending its pact with Prosensa earlier this week. To further complicate matters, Sarepta Therapeutics (SRPT 0.14%) earlier today reported 120-week results for eteplirsen, which showed continued six-minute walk test improvements relative to the placebo. In other words, drisapersen may not be a dead compound, but on a scale of dead to FDA-approved, it's a lot closer to the dead end at the moment. As such, I'd take today's gains with a grain of salt.

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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Stocks Mentioned

Sarepta Therapeutics Stock Quote
Sarepta Therapeutics
SRPT
$122.98 (0.14%) $0.17
GSK plc Stock Quote
GSK plc
GSK
$35.03 (1.27%) $0.44

*Average returns of all recommendations since inception. Cost basis and return based on previous market day close.

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