BACKGROUND: This study shows the results of a regional pharmacovigilance program on Natalizumab therapy in relapsing-remitting multiple sclerosis (RR-MS) patients after 3 years of experience.

MATERIAL AND METHODS: The primary objectives of this study were to estimate the incidence of expected and unexpected adverse effects correlated to Natalizumab therapy in a cohort of 88 RR-MS patients from Sicily, Italy, and to investigate the procedures adopted by the physicians to minimize the risk of developing severe adverse reactions correlated to Natalizumab therapy. Secondary objectives of this study were to evaluate the effectiveness of Natalizumab therapy for a careful examination of the risk/benefit ratio and to assess the actions undertaken in case of adverse reactions.

RESULTS: Among 88 RR-MS patients, 55.68% did not report any type of adverse reaction, 35.22% showed expected adverse reactions (58.70% slight, 22.58% moderate, and 19.35% severe), and 9.10% showed unexpected adverse effects (62.50% slight, 25.00% moderate, and 12.50% severe). Approximately 4.54% of the patients treated with Natalizumab interrupted the therapy. Overall, among all patients, 56.62% showed ameliorated condition, 32.53% had stable disease condition, and 10.85% worsened.

CONCLUSIONS: We provide a short overview of evidence, which may be useful to better characterize the efficacy and potential adverse effects correlated to Natalizumab therapy.

Keywords: Antibodies, Monoclonal, Humanized, Drug-Related Side Effects and Adverse Reactions, Multiple Sclerosis, Relapsing-Remitting, pharmacovigilance