Biogen Idec's 2Q profit rises 11 percent

The results also helped to allay Wall Street's continued concerns that sales might slow for Biogen's MS drug Avonex as its other treatment Tysabri gains ground in the market.

"The second-quarter results make it clear that Biogen's fundamentals are solid and that the company retains good earnings visibility," Cowen and Co. analyst Eric Schmidt said in a note to investors.

Shares of Biogen rose $4.43, or 6.6 percent, to $71.28.

The company earned $206.6 million, or 70 cents per share, compared with $186.1 million, or 54 cents per share, in the prior-year period. Revenue rose 28 percent to $993.4 million from $773.2 million.

Excluding charges for restructuring and acquired assets, the company earned 91 cents per share.

Analysts polled by Thomson Financial expected profit of 85 cents per share on revenue of $962.6 million.

Avonex sales rose 14 percent to $527.2 million, while sales of its other MS drug, Tysabri, more than tripled to $147.2 million.

Analysts have been carefully watching sales of Tysabri, with many still cautious because of its troubled past. Biogen pulled the drug from the market in 2005 after three patients developed a rare nervous system disorder. The FDA allowed it back on the market the following year, but only under a restricted distribution program.

Tysabri had international sales of $101 million and Biogen received $46 million from sales in the U.S. through its partner Elan. At the end of June, more than 31,800 patients were taking Tysabri worldwide, with 17,800 coming from the U.S. The company said there have still been no additional cases of the nerve disorder progressive multifocal leukoencephalopathy.