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: Medivation (Nasdaq: MDVN) popped 11% in intraday trading today after announcing it initiated a phase 2 clinical trial.

So what: Medivation is developing a drug called MDV3100 for the early treatment of advanced prostate cancer. Currently, there are limited options for treatment of this disease, with Dendreon's (Nasdaq: DNDN) Provenge as the established competitor. 

Now what: MDV3100 is already in phase 3 testing for advanced prostrate cancer. The new trial announced today should determine whether it is effective earlier in the course of the disease, which would open up a larger market. Johnson & Johnson (NYSE: JNJ), Exelixis (Nasdaq: EXEL) OncoGenex Pharmaceuticals (Nasdaq: OGXI) and its partner Teva Pharmaceuticals (Nasdaq: TEVA) are also testing drugs to treat the disease, with J&J appearing to be ahead of the others.

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Fool contributor Cindy Johnson does not own shares of any company named above. We Fools may not 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.