Efficacy of natalizumab in second line therapy of relapsing-remitting multiple sclerosis: results from a multi-center study in German speaking countries

Background: Natalizumab has been recommended for the treatment of relapsing-remitting multiple sclerosis (RRMS) in patients with insufficient response to interferon-beta/glatiramer acetate (DMT) or aggressive MS. The pivotal trials were not conducted to investigate natalizumab monotherapy in this patient population. Method: Retrospective, multicenter study in Germany and Switzerland. Five major MS centers reported all RRMS patients who initiated natalizumab >= 12 months prior to study conduction. Results: Ninety-seven RRMS patients were included [69% female, mean age 36.5 years, mean Expanded Disability Status Scale (EDSS) 3.4; 93.8% were pre-treated with DMT], mean treatment duration with natalizumab was 19.3 +/- 6.1 months. We found a reduction of the annualized relapse rate from 2.3 to 0.2, 80.4% were relapse free with natalizumab. EDSS improved in 12.4% and 89.7% were progression free (change of >/= 1 EDSS point). Eighty-six per cent of patients with highly active disease (>/= 2 relapses in the year and >/= 1 Gadolinium (Gd)+ lesion at study entry, n = 20) remained relapse free. The mean number of Gd enhancing lesions was reduced to 0.1 (0.8 at baseline). Discontinuation rate was 8.2% (4.1% for antibody-positivity). Conclusion: Natalizumab is effective after insufficient response to other DMT and also in patients with high disease activity.