SAN FRANCISCO -- Biogen Idec ( BIIB) provided upbeat guidance and new data for multiple sclerosis drug Tysabri on Monday at the JPMorgan HealthCare conference.Shares of the Cambridge, Mass.-based company, which plunged earlier this year after failing to attract a buyer, were up 95 cents a share, or 1.7%, to $56.17 in early trading. The company said Monday that it now expects that 2007 earnings per share will be at the top end of the previously announced guidance range of $2.60 to $2.70 a share, or 16% to 20% annual growth. Analysts surveyed by Thomson Financial are looking for $2.62 a share. For 2008, Biogen is eyeing adjusted earnings in the range of $3.20 to $3.35, also bullish compared to the consensus target of $3.20 a share. Separately, Biogen and partner Elan ( ELN) said that there are now 21,000 patients on MS drug Tysabri, compared to 17,000 at the end of the third quarter. Biogen expects 100,000 patients will be on Tysabri by the end of 2010. But Bear Stearns analyst Mark Schoenebaum said in a note to investors that this will mean the average rate of new patients will have to increase to 506 a week, compared to the current 308 patient/week. "This is an aggressive assumption, in our opinion," he noted.