Abstract

Since the use of interferon beta and glatiramer acetate in multiple sclerosis, a new step has been taken with the approval of natalizumab (Tysabri) in the relapsing remitting form of the disease. Natalizumab is a monoclonal antibody and binds to the alpha4 subunit of the alpha4B1 integrin. This antibody blocks the adhesion of activated T cells to endothelial cells and thereby reduces inflammation. In a randomized, placebo-controlled study, natalizumab reduced the rate of clinical relapses by 68 p. 100 and the risk of sustained progression of disability by 42 p. 100 over two years. All the MRI variables corroborate the clinical results with 92 p. 100 fewer lesions as detected by gadolinium enhanced MRI in the natalizumab group than in the placebo group. In a combination study with interferon beta-1a, two cases of progressive multifocal leukoencephalopathy, one of which was fatal, were diagnosed in natalizumab-treated patients. The safety of long-term use of natalizumab treatment is unknown. Promising results have been shown with other monoclonal antibodies, such as alemtuzumab.