Biogen Idec and Elan announced a global Phase 3b study, ASCEND, that is being conducted to evaluate the effectiveness of Tysabri (natalizumab) as a treatment for secondary-progressive multiple sclerosis (SPMS).

ASCEND is a double-blind, placebo-controlled study with SPMS patients being randomized to receive either Tysabri 300mg or placebo intravenously every four weeks for 96 weeks. ASCEND is expected to enroll approximately 850 patients in 15 countries. Study participants will be between the ages of 18 and 58, inclusive, with a diagnosis of SPMS for at least two years; an Expanded Disability Status Scale (EDSS) score between 3 and 6.5, inclusive; MS Severity Score of 4 or higher; documented, confirmed evidence of disease progression, independent of clinical relapses during the one-year prior to enrollment; and naïve to Tysabri treatment. The primary endpoint is to investigate whether treatment with Tysabri slows the accumulation of disability not related to relapses in subjects with SPMS.

Tysabri is an immunomodulator (integrin receptor antagonist) currently approved as a monotherapy for relapsing forms of MS, generally for patients who have had an inadequate response to, or are unable to tolerate, an alternative MS therapy.

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