Efficacy and tolerability of natalizumab in relapsing-remitting multiple sclerosis patients: a post-marketing observational study

To evaluate the efficacy and safety of natalizumab in patients with active relapsing remitting multiple sclerosis (MS). We included 285 MS patients receiving natalizumab. Clinical, neuroradiological and safety data were registered every 6 months. Neutralizing antibodies (NABs) were tested after 6 months of treatment. After 1 year, the annualized relapse rate decreased to 0.26, with a significant reduction compared to the previous year (2.13). At 24 months the proportion of relapse free patients was 78% while that of MRI free patients was 69%. Considering clinical and MRI cumulative activity, disease free patients were 63% at 24 months. A total of 18 patients showed NABs positivity. We reported 34 cases of treatment interruptions. In conclusion, our data confirm the remarkable efficacy of natalizumab in a group of patients with higher disease activity than that of pivotal studies.