Biogen Idec Inc. appeared to make peace with billionaire investor Carl Icahn on Monday, as it appointed a third Icahn-backed nominee to its board while Icahn Partners agreed to drop two other nominations.

Biogen will appoint one of its own candidates to the board, and secured Icahn's support for two other directors.

Icahn's nominee is Eric Rowinsky, a former executive of ImClone Systems. Icahn Partners LP attempted a takeover of ImClone in 2006 and eventually orchestrated the sale of ImClone to Eli Lilly & Co.

Biogen appointed Stephen Sherwin, the former chairman and CEO of Cell Genesys.

Icahn Partners also agreed to vote in favor of Biogen's other nominees — current directors Nancy Leaming and Brian Posner — at the company's upcoming annual meeting. Icahn Partners is withdrawing the nominations of two other candidates and a proposal to limit the size of Biogen's board to 12.

The appointments of Rowinsky, 53, and Sherwin, 61, temporarily expand Biogen's board to 13 members. The company said President and CEO James Mullen and former chairman Bruce Ross will complete their terms on the board, but will not stand for re-election at the 2010 annual meeting. After they depart, there will be 12 directors.

Icahn Partners owns about 9 percent of Biogen. Icahn, an activist shareholder, has criticized the company and launched a campaign to take control of the board in 2008. He hoped to engineer a sale of Biogen to a large drugmaker.

Two other Icahn nominees, Alexander Denner and Richard Mulligan, won spots on the Biogen board in 2009 after a proxy fight.

Biogen's drugs include Tysabri, a treatment for multiple sclerosis and Crohn's disease, Avonex for MS, and Rituxan for lymphoma and rheumatoid arthritis.

In midday trading, Biogen shares rose 33 cents to $59.96. Earlier shares set a 52-week high of $60.28.