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 biotechnology company Medivation (Nasdaq: MDVN) soared 19% earlier this morning after drug rival Janssen Pharmaceuticals, owned by Johnson & Johnson (NYSE: JNJ), reported it was unblinding its clinical trial of Zytiga.

So what: The real news here appears to be that Medivation's MDV3100 has shown actual clinical significance when it comes to extending prostate cancer survival rates, whereas J&J's experimental drug simply has not. Zytiga previously had been shown to extend survival rates to 4.8 months from 3.9 months, but that could just as easily be because of the population make-up of the study.

Now what: This news could also hurt Dendreon's (Nasdaq: DNDN) prostate treatment, Provenge, whose market share could be at risk with Zytiga being tested for different stages of prostate cancer treatment. And at least for the near term, it takes the possibility of a Dendreon buyout off the table. MDV3100 from Medivation isn't approved yet, but the path continues to be cleared for its potential approval and the chance at owning a lion's share of the market.

Craving more input? Start by adding Medivation 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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