Biotech stock Dendreon Corporation (NASDAQ:DNDN - 4.21) has been targeted by call buyers over the last week, according to data from the major options exchanges. During the past five sessions, speculators on the International Securities Exchange (ISE) and Chicago Board Options Exchange (CBOE) have bought to open 3,490 calls on DNDN, along with only 365 puts. In other words, 9.56 times more calls than puts have been purchased during this time frame, revealing a strong preference for bullish bets over bearish.

Checking out the front-month series -- which is due to expire at the end of this week -- peak call open interest of 6,877 contracts can be found at the November 5 strike. DNDN is trading just north of the $4 level, which means all of these calls are out of the money. In fact, as expiration approaches, the biotech concern could actually encounter some options-related resistance around the $5 level.

In today's trading, however, DNDN is enjoying a healthy pop after Needham Research started coverage of the stock with a "buy" rating and $7 price target. It's a rare bullish note for the security, which currently sports 12 "holds" and six "sell" or "strong sell" recommendations from analysts.

Technically speaking, DNDN has shed roughly 47% of its value year-to-date -- but the shares are chipping away at that deficit with today's gain of more than 4%. However, the stock is staring up at familiar resistance from its 10-week moving average, which has guided DNDN lower since early March.