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 clinical-stage biopharmaceutical company Keryx Biopharmaceuticals scorched higher by as much as 99% after reporting positive late-stage data on its kidney disease drug, Zerenex.

So what: Zerenex, which targets hyperphosphatemia -- a complication that occurs at end-stage renal disease and can lead to calcification of the arteries leading to the heart -- performed remarkably well in trials. As my Foolish colleague Keith Speights noted, Zerenex "Reduced patients' mean serum phosphorus levels by 0.3 mg/DL during the four-week efficacy assessment period, while patients taking placebo saw their levels go up by 1.9 mg/DL." No one expected this much statistical success from Zerenex, which met many of its secondary endpoints as well, and the company is now readying to file for approval in the second quarter.


Now what: The results were nothing short of impressive, but I still have doubts heading into the FDA approval process that Zerenex could run into issues. The clinical studies speak for themselves, but from a commercial manufacturing standpoint, I'm almost certain Keryx lacks the capital to meet the FDA's rigorous safety and production requirements. As for me, I'd use today's huge run-up as a chance to calmly walk out the door and tip the doorman on the way out.

While you can certainly make huge gains in biotech and pharmaceuticals, the best investing approach is to choose great companies and stick with them for the long term. In our free report "3 Stocks That Will Help You Retire Rich," we name stocks that could help you build long-term wealth and retire well, along with some winning wealth-building strategies that every investor should be aware of. Click here now to keep reading.

The article Why Keryx Biopharmaceuticals Shares Nearly Doubled originally appeared on Fool.com.

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. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.

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