Natalizumab-treated patient characteristics.

Only the long-lasting and relevant therapies are reported. The interval between IFNβ 1a or GA therapies and natalizumab was at least of 30 days. plmMS received MTX from February 2004 to November 2006, nMS3 from February 2003 to March 2005 and nMS4 from July 2004 to February 2007.**There was no trend of EDSS up- or downwards.***Time point in which PML was diagnosed. Four different samples were obtained over a 1-month period. For the other time points and in all other patients, only one biological sample was analyzed.F, female; M, male; y, years; w, weeks; IFN, interferon; MTX, mitoxantrone; GA, glatiramer acetate; na, not available.