Effectiveness and Adverse Events of Use of Natalizumab in a Brazilian Cohort of Patients With Multiple Sclerosis

Purpose: Natalizumab (NTZ) is a monoclonal antibody with confirmed efficacy in white populations with recurrent-remitting multiple sclerosis (RRMS); there are few studies, however, in mixed-race populations. Real-world studies of NTZ are needed to better understand the drug's effectiveness. This study evaluated the effectiveness and adverse events of NTZ in a cohort of Brazilian patients with MS, as well as the impact of clinical and demographic factors on patient response to treatment.

Methods: This multicenter, Brazilian observational study was conducted from January 2011 until December 2016 and included patients with RRMS (McDonald criteria 2005 and 2010) aged ≥18 years treated with NTZ for at least 3 months. Demographic, clinical, and radiologic data were obtained from medical records and during follow-up visits. The primary outcomes investigated were the absolute number of relapses and annualized rate of relapses, change in Expanded Disability Status Scale value, and presence of new lesions on magnetic resonance imaging after starting NTZ treatment; the occurrence and type of adverse events were also analyzed. In addition, the impact of demographic and clinical prognostic factors and radiologic activity on the effectiveness of NTZ was measured. Descriptive and univariate statistical analyses used a significance level of P < 0.05.

Results: The study enrolled 56 patients; 64% were women, and 36% were of African descent. There was a significant reduction in the mean absolute number (P = 0.001) and in the annualized rate (P = 0.001) of relapses and in the radiologic activity of the disease (P = 0.001). Furthermore, 71% of patients showed no increase in Expanded Disability Status Scale score after 1 year of treatment. The effectiveness of NTZ was not associated with the presence of clinical and demographic prognostic factors, and the most frequent adverse events during the use of NTZ were gastrointestinal symptoms; there were no cases of progressive multifocal leukoencephalopathy.

Implications: According to patients' reports and clinicians' observations regarding clinical and radiologic benefits and tolerability to adverse events, the use of NTZ was favorable in this Brazilian MS cohort, regardless of the presence of unfavorable prognostic factors.