Shares of

Biogen

(BGEN)

rose sharply Tuesday after the biotech announced an upside surprise for its first quarter.

The company revised guidance upward, saying revenue for the quarter ended March 31 would be up about 5% to $320 million, while earnings would be in the range of 39 cents to 43 cents per share, well over guidance given in late January that ranged from 31 cents to 38 cents per share.

In recent trading, Biogen was up $3.78, or 12.5%, to $34.07.

The company also increased full-year guidance to a range of $1.72 to $1.85 per share from $1.63 to $1.78. Those estimates don't include possible one-time charges.

Revenue for the year would be near the high end of the range given in late January, according to the company.

Wall Street estimates for the company were for earnings of 37 cents per share on $305 million in revenue for the first quarter, according to Thomson Financial/First Call.

In a statement released with the new guidance, company CEO Jim Mullen said Biogen had succeeded in cutting costs and driving increased sales of its multiple sclerosis drug Avonex.

The third goal, for a successful launch of its psoriasis drug Amevive, is more problematic. The drug faces very stiff competition from

Genentech's

(DNA)

Raptiva and

Amgen's

(AMGN) - Get Report

Enbrel.

Some analysts, anticipating a tough launch for Amevive, lowered estimates for its sales and Biogen's shares have suffered for it.