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 drug developer Dendreon (Nasdaq: DNDN) plunged 21% on Tuesday after its quarterly results and outlook disappointed Wall Street.

So what: Dendreon's first-quarter loss narrowed to $103.9 million (versus a loss of $112.8 million in the year-ago period), but modest sales of its prostate cancer treatment Provenge, coupled with an equally uninspiring full-year outlook, are reigniting concerns over its prospects going forward. Management said it would take "time and significant education" to see higher adoption rates for Provenge, but the continued losses and weak sales are weighing on investor patience.   

Now what: Dendreon expects second-quarter sales growth in the low single digits and sees only modest growth for the rest of 2012. "We continue to work on generating data for Provenge and our pipeline," CEO John Johnson reassured analysts on a conference call, "and we are preparing Provenge for global expansion." While Dendreon remains just too volatile for average Fools, today's big pullback -- the stock is now off a whopping 80% from its 52-week high -- might be an attractive opportunity for biotech-savvy bargain hunters.

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