CHICAGO - Biogen Idec Inc launched a hostile $355 million takeover bid for Facet Biotech Corp on Monday, two weeks after Facet's board rejected an identical offer.

Facet and Biogen are jointly developing daclizumab, a drug for multiple sclerosis, and volociximab, for solid tumors.

Biogen's $14.50-a-share offer represents a 64 percent premium over the $8.82 closing price of Facet shares on Sept. 3, when Biogen first offered that price. The bid expires Oct. 19.

Biogen's offer to Facet shareholders follows a written proposal to Facet's board seeking to acquire all outstanding shares of Facet at the same price.

Facet's board rejected the proposal on Sept. 8, saying the offer was inadequate and valued only the company's cash, marketable securities and restricted cash while placing no value on operating and other assets.

Biogen on Monday said it had sent a letter to Facet's board stating its contention that Facet's available cash is considerably below the Biogen offer price and that the takeover bid assigns meaningful value to daclizumab.

Biogen offered $15.00 a share for Facet on Aug. 17, before Facet announced a collaboration with Trubion Pharmaceuticals Inc. Biogen said the collaboration reduced Facet's value.

Shares of Biogen, which makes the multiple sclerosis drugs Avonex and Tysabri, rose 10 cents to $50.10 in morning trading on Nasdaq. Shares of Facet were down 5 cents to $16.50. (Reporting by Susan Kelly, editing by Gerald E. McCormick and John Wallace)