Drug developer Dendreon's (NASDAQ:DNDN) shareholders had a good day yesterday, as the stock rose 5% on positive regulatory news from the U.S. Food and Drug Administration.

After completing the filing of an application for marketing approval of its lead drug candidate, Provenge, back in November, Dendreon finally got word from the FDA yesterday that the prostate cancer treatment was granted a priority review. This shortens the time the FDA will take to either accept or reject the drug for marketing from the more common 10 months to only six.

Investors should remember that granting Provenge a priority review is no guarantee of FDA marketing approval, nor does it lower the agency's standards of judgment. It's simply an acknowledgement that Provenge potentially treats a disease with no other good treatment options currently available.

Though a priority review doesn't alter Provenge's odds of approval, an earlier ruling could mean millions of dollars in sales for Dendreon, if Provenge gets the nod from the FDA.

The FDA will try to rule on Provenge by May 15 -- in this process, that's known as the PDUFA date. I've previously predicted that the FDA will give Dendreon an approvable letter for Provenge, since its phase 3 trial results have been muddled so far. With the PDUFA date only months away, I won't have to wait long to see whether my prediction comes true.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. The Fool has a disclosure policy.