Natalizumab to Fingolimod Switching in Multiple Sclerosis: Results from a and#8220;Real Wordand#8221; Retrospective Analysis

Fingolimod is an alternative for patients with multiple sclerosis who discontinue natalizumab because of leukoencephalopathy risk. However, the interruption of natalizumab might cause disease reactivation. We aimed to describe the disease course of patients switching to fingolimod after treatment with natalizumab or β-interferon, in a real-world setting, through a retrospective analysis of data in patients with multiple sclerosis that receiving fingolimod at a single centre in Italy. Ninety patients were divided into two groups: patients switching to fingolimod from natalizumab (n = 43, Group 1), and treatment naive (n=5) plus patients switching from β-interferon (n = 42) (Group 2). In Group 1, the mean annualised relapse rate significantly increased from 0.36 at natalizumab discontinuation to 0.80 after natalizumab washout and 1.12 after the first 3 months of fingolimod, decreasing thereafter to 0.49 by the end of followup. In Group 2, the relapse rate significantly decreased from 1.16 to 0.47 at the end of follow-up. Relapses during natalizumab washout predicted increased disease activity during the first 3 months of fingolimod (p = 0.043). We conclude that fingolimod has a delayed effect in patients switching from natalizumab versus treatment-naive patients or those switching from β-interferon. Worsening of disease activity during the washout period may be predictive of treatment failure.