Relapses in patients treated with fingolimod after previous exposure to natalizumab.

In post hoc analyses of an open-label, phase 3b study (FIRST), relapse rates during 4 months of fingolimod therapy were compared in patients with and without previous natalizumab exposure. Reductions in the proportion of patients experiencing relapses and annualized relapse rates (ARRs) from years 1 and 1-2 pre-study were evident between months 1 and 2 of fingolimod treatment, and were most pronounced in natalizumab-naïve patients and those who discontinued natalizumab >6 months pre-study. Patients who discontinued natalizumab 3-6 months pre-study had a peak ARR during month 1 of fingolimod treatment, followed by a decrease during months 2-4. These data indicate that fingolimod has the potential to reduce disease reactivation but that timing of treatment initiation may be critical for achieving an optimal effect.