Pediatric-onset Multiple Sclerosis treatment: a multicentre observational study comparing natalizumab with fingolimod

Background: Pediatric-onset Multiple Sclerosis (POMS) patients show more inflammatory disease compared with adult-onset MS. However, highly effective treatments are limited with only fingolimod being approved in Italy and natalizumab prescribed as off-label treatment. Objectives: to compare the efficacy of natalizumab versus fingolimod in POMS. Methods: This is an observational longitudinal multicentre study including natalizumab- and fingolimod-treated POMS patients (N-POMS and F-POMS, respectively). We collected Annual Relapse Rate (ARR), Expanded Disability Status Scale (EDSS), Symbol Digit Modality Test (SDMT), and MRI activity at baseline (T0), 12-18 months (T1), and last available observation (T2). Results: We enrolled 57 N-POMS and 27 F-POMS patients from six Italian MS Centres. At T0, N-POMS patients showed higher ARR (p = 0.03), higher EDSS (p = 0.003) and lower SDMT (p = 0.04) at baseline compared with F-POMS. Between T-0 and T-1 ARR improved for both N-POMS and F-POMS (p < 0.001), while EDSS (p < 0.001) and SDMT (p = 0.03) improved only for N-POMS. At T-2 (66.1 +/- 55.4 months) we collected data from 42 out of 57 N-POMS patients showing no further ARR decrease. Conclusion: Both natalizumab and fingolimod showed high and sustained efficacy in controlling relapses and natalizumab also associated to a disability decrease in POMS. This latter effect might be partly mediated by the high inflammatory activity at baseline in N-POMS.