Drug insight: using monoclonal antibodies to treat multiple sclerosis.

Multiple sclerosis (MS) is an immunopathological, presumably autoimmune, disease of the CNS. Several immunomodulatory treatments, including various preparations of interferon-beta, glatiramer acetate and mitoxantrone, have been approved for MS therapy. Because these agents are only partially effective, the search for better therapies continues. Therapeutic monoclonal antibodies (mAbs), a class of biotechnological agents, allow the precise targeting of molecules involved in pathological processes. Therapeutic mAbs have shown much promise in the treatment of many disorders, including inflammatory and putative autoimmune diseases such as MS. These agents have intrinsic limitations, however, such as induction of neutralizing 'anti-antibodies', systemic inflammatory reactions and severe adverse effects, some of which remain to be explained. Most notably, natalizumab (Tysabri), a mAb against alpha4 integrin, was very effective in suppressing MS activity, but had to be withdrawn from the market because several treated patients developed progressive multifocal leukoencephalopathy. This article reviews the state of development of various therapeutic mAbs for MS treatment.