50% Gain for That?

On the surface, Alnylam Pharmaceuticals (NAS: ALNY) going up more than 50% yesterday after releasing clinical trial data isn't all that weird. Exelixis (NAS: EXEL) jumped 32% when phase 2 data on cabozantinib was released and another 20% upon positive phase 3 data. Threshold Pharmaceuticals (NAS: THLD) ran up 40% the day it released positive phase 2b data for its pancreatic cancer drug.

But Alnylam's data for ALN-TTR02 come from a phase 1 trial in healthy volunteers. There's no direct proof the drug will successfully treat TTR-mediated amyloidosis.

And Pfizer (NYS: PFE) seems to have a substantial head start on Alnylam's ALN-TTR02. Pfizer was recently turned down for approval of Vyndaqel in the U.S., with the Food and Drug Administration asking for data from a second phase 3 study currently under way. Vyndaqel is already approved in Europe, where the disease is more prevalent than it is in the U.S.

So what's got investors so excited? ALN-TTR02 knocked down the level of TTR protein in healthy volunteers, which should translate well to treating patients who have mutations in their TTR genes. The mutant protein clumps, which causes damage to the peripheral nerves and heart and all kinds of bad things to happen. If there's less mutant protein, there should be fewer amyloid clumps.

Or so the theory goes. The only way to know for sure is to see the drug in action in patients with TTR amyloidosis.

More important in the overall scheme of things, and possibly a bigger influence on the stock jump yesterday, the clinical trial confirms the approach that Alnylam is taking. The biotech is developing RNAi technology that targets RNA, the intermediary step between DNA and proteins. ALN-TTR02 was able to knock down the production of the TTR protein in a few days and keep it down for a few weeks. If it works this well on TTR, it should work well on other proteins.

Even after the 50% jump, Alnylam still has a market cap under $1 billion, lower than it was back in 2008 when there was a lot less proof that RNAi could work as a therapeutic. The valuation back then was a bit crazy, but seems considerably more reasonable now.

Looking for more high-tech stock ideas? Check out the Fool's free report, "The Next Trillion-Dollar Revolution," where you'll find a company quietly cashing in on the booming smartphone market. Click here to get your free copy.

The article 50% Gain for That? originally appeared on Fool.com.

Fool contributor Brian Orelli holds no position in any company mentioned. Click here to see his holdings and a short bio. The Motley Fool owns shares of Exelixis. Motley Fool newsletter services have recommended buying shares of Exelixis and Pfizer. The Motley Fool has a disclosure policy.We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. Try any of our Foolish newsletter services free for 30 days.

Copyright © 1995 - 2012 The Motley Fool, LLC. All rights reserved. The Motley Fool has a disclosure policy.