Biogen Idec and Elan Corporation plc have submitted an application for approval of Antegren (natalizumab) as a treatment for multiple sclerosis (MS) in Canada and expect to submit applications in Australia and Switzerland, based on one-year data from the ongoing Phase III trials. The companies also anticipate that the first release of the one-year data from these trials will be upon approval of natalizumab by the US FDA.

The companies have submitted their application to regulatory authorities in Canada and anticipate submissions will be filed in Australia and Switzerland in the second half of 2004. The companies previously announced that the FDA designated natalizumab for Priority Review and Accelerated Approval, and that the European Medicines Agency validated their application.

Based on the FDA's designation of Priority Review for natalizumab in MS, the companies anticipate action by the FDA approximately six months from the submission date, rather than 10 months for a standard review. On May 25, 2004, the companies announced they had previously submitted the Biologics License Application for the approval of natalizumab for MS.

The decision to file applications for approval in Canada, Australia and Switzerland was made after discussions with the countries' respective regulatory agencies of the one-year data from the two ongoing two-year Phase III trials in MS. After discussion with the regulatory authorities and clinical investigators, the companies expect to release the one-year data upon US approval, in order to protect the integrity of the two-year trials. The companies anticipate that the two-year data will be available beginning in the first half of 2005.

The regulatory review of natalizumab will be based on one-year data from two ongoing Phase III trials, Affirm (natalizumab safety and efficacy in relapsing-remitting MS) and Sentinel (safety and efficacy of natalizumab in combination with Avonex (Interferon beta-1a)), which evaluate the ability of natalizumab to slow the progression of disability and reduce the rate of clinical relapses in patients with relapsing-remitting MS.

Natalizumab, a humanized monoclonal antibody, is the first alpha-4 antagonist in the new selective adhesion molecule (SAM) inhibitor class. It is designed to inhibit the migration of immune cells into tissues where they may cause or maintain inflammation.