Sales of Tysabri stopped in United States

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Summary
Biogen Idec and Elan Corporation announced February 28 they have voluntarily withdrawn Tysabri^® (natalizumab) for sale in the United States and have stopped using it in clinical trials. They have asked doctors to stop prescribing the medication. The suspension follows disclosure of the death of one person because of the development of a rare but very serious central nervous system disease called progressive multifocal leukoencephalopathy (PML). A second person is suspected of having PML. Both people had received Tysabri in combination with Avonex^® (interferon beta-1a) for more than two years in a clinical trial setting.

The companies, which are both involved in the development and marketing of the medication, have said they will work with clinical investigators to evaluate people who have been treated with Tysabri and with medical experts and government regulatory agencies to investigate the adverse events. Biogen Idec Canada said it had already informed Health Canada of the new developments.

Tysabri was approved by the US Food and Drug Administration (FDA) on November 23, 2004. It is currently under review by Health Canada for approval in Canada as a therapy for multiple sclerosis.

Biogen Idec Canada has available an information line in English and French for further inquiries about Tysabri (natalizumab): 1-877-674-6365. For background information about Tysabri please see the following Medical Update Memos:

• FDA approves natalizumab (Tysabri^® - formerly known as Antegren) for relapsing forms of MS

• Two-year results released from Tysabri clinical trial

ASK MS Information System Code: 1.4.1.12.2.r

Disclaimer
The Multiple Sclerosis Society of Canada is an independent, voluntary health agency and does not approve, endorse or recommend any specific product or therapy but provides information to assist individuals in making their own decisions.