Alemtuzumab in multiple sclerosis: latest evidence and clinical prospects.

Alemtuzumab was first used in multiple sclerosis in 1991. It is a monoclonal antibody which is directed against CD52, a protein of unknown function on lymphocytes. Alemtuzumab causes a lymphopenia, following which homeostatic reconstitution leads to prolonged alteration of the immune repertoire. This reduces the risk of relapse and disability accumulation in multiple sclerosis; it is the only drug to show superiority over interferon β-1a in disability outcomes in a monotherapy phase III trial. It should be used with a parallel risk management programme to identify the principal adverse effects of alemtuzumab, especially secondary autoimmunity months or years later, mainly against the thyroid but also immune thrombocytopenia. This review charts the development of alemtuzumab as a drug for multiple sclerosis and summarizes the latest clinical trial data.