Predictors for multiple sclerosis relapses after switching from natalizumab to fingolimod

Background: Risks of natalizumab (NAT) therapy have to be weighed against disease recurrence after stopping NAT. Objectives: The objective of this paper is to identify risk factors for recurrence of relapses after switching from NAT to fingolimod (FTY) in relapsing-remitting multiple sclerosis (RRMS). Methods: Patients (n = 33) were treated with NAT for 1 year, and then switched to FTY within 24 weeks (mean follow-up on FTY 81.1 (SD 26.5) weeks). Annual relapse rates (ARR) and Expanded Disability Status Scale scores (EDSS) were assessed. Descriptive statistics, univariate logistic regression analysis, and receiver operating characteristic curves were conducted. Results: Overall, 20 patients (61%) had relapses after discontinuation of NAT and 16 (48%) during FTY therapy. The maximum incidence of relapses occurred between weeks 13-24 post-NAT. The last EDSS during the switching period predicted relapses during subsequent FTY therapy. EDSS >3 separated most powerfully between the groups (sensitivity 64%, specificity 88%) and significantly predicted relapses (relative risk 3.27, 95% CI: 1.5-7.3). Seventy-five percent of patients with EDSS 3 remained free of relapses, compared to 18% of patients with EDSS >3. Conclusions: There was an increase of the ARR in the first year after switching from NAT to FTY. Last EDSS during the switching period was a predictor of relapses during FTY.