Natalizumab strongly suppresses cortical pathology in relapsing-remitting multiple sclerosis

Background: Since cortical pathology has been indicated to play a relevant role in the physical and cognitive disability of multiple sclerosis (MS) patients, this study aims to analyze the efficacy of natalizumab in slowing down its progression. Methods: A total of 120 relapsing-remitting MS patients completed a 2-year prospective study: 35 received natalizumab, 50 received interferon beta-1a or glatiramer acetate (immunomodulatory agents - IMA) and 35 remained untreated. Forty healthy subjects constituted the reference population. Clinical and magnetic resonance imaging (MRI) evaluations (including cortical lesions and atrophy) were performed at baseline and after 2 years. Results: Natalizumab significantly reduced accumulation of new cortical lesions (0.2 +/- 0.6, range 0-3) compared to immunomodulatory agents (1.3 +/- 1.1 togli spazio, range 1-6, p=0.001) and no treatment (2.9 +/- 1.5, range 1-8, p<0.001). The percentage of patients with new cortical lesions was also lower in natalizumab-treated patients (20%) compared to IMA-treated and untreated patients (68.0% and 74.2%; p<0.001 for both comparisons). Furthermore, the progression of cortical atrophy was significantly reduced by natalizumab (% change=1.7%) compared to IMA (3.7%, p=0.003) and no therapy (4.6%, p<0.001). Finally, a greater percentage (51.4%) of natalizumab-treated patients remained disease-free (no clinical or MRI evidence of disease activity or progression) compared to IMA-treated (18%, p=0.001) and untreated patients (5.7%, p<0.001). Conclusions: Natalizumab treatment significantly decreases cortical lesion accumulation and cortical atrophy progression in severe relapsing-remitting MS. While supporting the inflammatory origin of cortical lesions, our results highlight the significant impact of natalizumab on cortical pathology.