Review on PML Risk Stratification in Natalizumab-Treated Multiple Sclerosis Patients

Natalizumab (NAB) is the first approved among the monoclonal antibodies tested for the treatment of relapsing forms of multiple sclerosis (MS). However, despite the high effectiveness of this drug in MS, the risk of JCV infection within the central nervous system (CNS) leading to progressive multifocal leukoencephalopathy (PML), a potentially lethal condition, is of high concern. Consequently, attempts to stratify patients treated with NAB into those of higher or lower risk for developing PML are urgent. For the time being, three key factors seem to determine the risk of PML: treatment duration beyond 24 months, prior immunosuppressive therapy and the serum anti-JCV antibody detection. Clearly, serum JCV antibody detection represents a tool for PML risk stratification in MS patients treated with NAB. The large variety of methods published so far has resulted in controversies with regard to JCV seroprevalence. However, a standardized assay is now available. (Archives of Neuropsychiatry 2011; 48 Supplement 2:61-3)