An observational study of the effectiveness and safety of natalizumab in the treatment of multiple sclerosis

Aim. To analyse the safety and effectiveness of natalizumab in the treatment of multiple sclerosis in a real clinical practice setting and according to the approved indications. Patients and methods. All patients with multiple sclerosis treated with natalizumab in our centre were evaluated. The clinical and radiological disease activity during the first year of treatment was analyzed in patients who received at least 12 doses of the drug. The data regarding moderate and severe adverse events in the entire study sample was also evaluated. Results. A total of 112 patients were included in the study, of which 110 had been previously treated with other drugs and 76 had received at least 12 doses of natalizumab. In this group, the annualized relapse rate was reduced by 89% compared to the preceding year and 80% of patients were free from relapses after one year of treatment. Nine percent of patients exhibited 3-month confirmed disability progression. At month 12, the mean number of gadolinium-enhancing lesions on brain MRI was decreased by 99% compared to the pre-treatment MRI. During the first year of treatment, 76% of patients remained free from clinical activity and 33% remained free from both clinical and radiological disease activity. Twenty-nine percent of patients had at least one moderate or severe adverse event, which led to treatment discontinuation in 6%. Four percent of patients experienced immediate hypersensitivity reactions. Conclusion. This study suggests that natalizumab is effective in reducing disease activity in patients with relapsing multiple sclerosis and inadequate response to other therapies, with a favorable risk-benefit ratio. © 2011 Revista de Neurología.