Biogen Idec, Elan Pull MS Drug Tysabri From Market

Biogen Idec and Elan have suspended sales of their multiple sclerosis (MS) drug Tysabri following reports that the product might have contributed to a pair of serious adverse events, including one patient death.

Tysabri (natalizumab), which was approved by the FDA Nov. 23, 2004, as a treatment for relapsing forms of MS, is considered to be one of the companies' most promising products. The drug had sales of nearly $10 million during its first month on the market and Wall Street analysts have predicted that Tysabri's sales could reach $3 billion annually. Ratings agency Standard & Poor's recently named the drug one of its top 10 products to watch in 2005.

The drug's once-promising future, however, is now in limbo following two recent adverse events that occurred in patients treated with Tysabri in combination with Avonex (interferon beta-1a), Biogen Idec's older MS treatment. The adverse events, which occurred during clinical trials, involved one fatal, confirmed case and one suspected case of progressive multifocal leukoencephalopathy, a rare and frequently fatal, demyelinating disease of the central nervous system. Both patients received more than two years of Tysabri therapy in combination with Avonex, the companies said.

To view the Dear Healthcare Professional Letter regarding Tysabri, go to http://www.tysabri.com/hcp.pdf (http://www.tysabri.com/hcp.pdf).