Switching from natalizumab to fingolimod treatment in multiple sclerosis: real life data from the Austrian MS Treatment Registry.

Objectives: To compare the efficacy of natalizumab (NTZ) and fingolimod (FTY) in the treatment of relapsing-remitting multiple sclerosis (MS) in sequential use in common and as a function of transition periods in a nationwide observational cohort using prospectively collected data from a real-life setting.

Materials And Methods: We included 195 patients from the Austrian MS Treatment Registry, who had started treatment with NTZ at any time since 2006 and stayed on NTZ for at least 24 months, switched afterwards within 1 year to FTY and stayed on FTY for at least another 12 months. Transition periods between NTZ and FTY were grouped into three different intervals: < 3 months (135 patients), 3-6 months (44 patients), and 6-12 months (16 patients).

Results: Estimated mean annualized relapse rates (ARR) over a mean treatment period of 44 months were 0.26 for NTZ and 0.32 for FTY (p = 0.381) over 46 months. In the treatment gap, differences were found concerning the relapse probability, seven (5.2%) patients in the < 3 months group, six (13.6%) in thef 3-6 months group, and seven (43.8%) in the 6-12 months group (p < 0.001). After this treatment gap, no significant differences concerning ARR, EDSS change, EDSS progression, and regression were observed regardless the proceeding transition periods. Significantly higher efficacy of NTZ compared to FTY in sequential use was found regarding EDSS change, EDSS progression, and EDSS regression sustained for 12 and 24 weeks.

Conclusions: First, we here show an increased short-time risk for relapses during the treatment gap between NTZ and FTY therapy, dependent on the length of transition time. Second, the disease course after switching to FTY remained stable in the long-term evaluation. Therefore, switching from NTZ to FTY in a real-world setting appears efficacious and safe, but this data advocate for a short switching gap of 3 months or less.