Earnings season is upon us, and Biogen Idec (Nasdaq: BIIB) stepped up to report full-year and fourth-quarter results yesterday. It's been a busy, rumor-filled couple of months for Biogen, but the Stock Advisor pick already took much of the mystery out of its financial results by giving its 2008 guidance a while ago.

For 2007, Biogen's revenue rose 18%, and non-GAAP net income gained 13% year over year. Non-GAAP earnings totaled $2.74 per share. The previously announced 2008 guidance calls for revenue growth of 15% to 20% this year, and earnings per share of $3.20 to $3.35. Biogen's aiming for 20% average non-GAAP earnings-per-share (EPS) growth through 2010.

No discussion of a Biogen earnings call would be complete without a mention of its multiple sclerosis treatment Tysabri. Tysabri worldwide sales by Biogen and Elan (NYSE: ELN) in the fourth quarter totaled $129 million, compared to the $93 million the drugmakers brought in during the third quarter. Just last month, the FDA approved Tysabri to treat Crohn's disease in the U.S. as well.

Surprisingly, there didn't appear to be much Tysabri cannibalization on sales of Biogen's other multiple sclerosis (MS) treatment Avonex last quarter. Avonex sales grew a very healthy 15% year over year in the fourth quarter (partly because of price and foreign exchange gains, though). During the conference call, Biogen stated that patients leaving Teva's (NYSE: TEVA) Copaxone accounted for the biggest source of MS patients who switched therapies onto Tysabri.

The big news with Biogen as of late has been the continued activities of Carl Icahn. The latest wrinkle in the story of Icahn's involvement with Biogen is his worry that the biotech may be looking to do a large acquisition. Last week, Icahn pushed to get a seat on Biogen's board to prevent this from happening, and possibly to give the company another push toward a sale.

On the conference call, Biogen's CEO squashed the rumors that it might have a large acquisition in the works, saying that there were currently no large drugmakers to acquire that meet the "dual test of strategic fit at attractive valuation." At least that's one Biogen rumor we can put to rest for a little while.

Biogen is an active Stock Advisor pick.

Fool contributor Brian Lawler does not own shares of any company mentioned in this article. The Fool's disclosure policy is rumored to be running for president.