Clinical effectiveness of reduced fingolimod dose in relapsing remitting multiple sclerosis-a Portuguese cohort

Background Fingolimod is an oral daily treatment for relapsing remitting multiple sclerosis (RRMS). A decrease in lymphocytes count is a common side effect, whereby clinicians occasionally propose a reduced dose rather than its discontinuation. However, current data on the effectiveness of these regimens are scarce and contradictory. Our objective was to investigate if the fingolimod effectiveness is maintained with reduction in dosing frequency. Methods Retrospective and observational study of RRMS patients taking fingolimod-nondaily (FTY-ND) for at least 6 months. Propensity score-based matching was performed to select patients taking daily dose (FTY-ED) with comparable baseline characteristics: age, sex, disease duration, annualized relapse rate (ARR), and expanded disability status scale (EDSS). Afterwards, clinical and laboratorial assessment was evaluated in both groups. Results Thirty-six patients were included in each group (FTY-ED vs. FTY-ND). Decrease in lymphocytes count was the main reason for switching to FTY-ND (88.9%). Previous treatment with natalizumab was inversely associated with risk of reducing dose (OR 0.253, 95%CI = 0.08-0.807,p = 0.016). There were no significant differences in clinical disease activity between patients FTY-ED vs. FTY-ND: mean ARR 0.4 vs. 0.3 (p = 0.247), median EDSS 2.0 vs. 2.0 (p = 0.687), and proportion of patients with EDSS increase 8.3% vs. 13.9% (p = 0.453). FTY-ND was overall well tolerated and was associated with an increase in the mean lymphocytes count (362 +/- 103 cells/mm(3)to 541 +/- 183 cells/mm(3),p < 0.001). Conclusion These data suggest that the effectiveness of FTY is maintained despite the reduction of the dose, minimizing the most common adverse events. These findings warrant further confirmation, ideally with randomized clinical trials.