[LINK]Biogen Idec and Elan Corporation have just announced the voluntary suspension of Tysabri from the market and from all clinical trials due to safety concerns. Tysabri was approved for marketing in November 2004.According to the company press release, "This decision is based on very recent reports of two serious adverse events that have occurred in patients treated with TYSABRI in combination with AVONEX® (Interferon beta-1a) in clinical trials. These events involve one fatal, confirmed case and one suspected case of progressive multifocal leukoencephalopathy (PML), 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."