Natalizumab for multiple sclerosis: Appraising risk versus benefit, a seemingly demanding tango

Introduction: Natalizumab is a highly effective monoclonal antibody used for the treatment of multiple sclerosis (MS). It reduces relapses, delays the onset of disease progression and improves disease outcomes in relapsing-remitting MS. However, treatment with natalizumab is associated with progressive multifocal leukoencephalopathy (PML), a severe opportunistic brain infection with John Cunningham virus. Areas covered: In this review, we discuss the mechanism of action, results of pivotal studies, clinical use and adverse effects associated with natalizumab therapy with emphasis on PML. A risk stratification strategy to optimize natalizumab therapy is included. This review also summarizes the alternative and upcoming therapies available for the treatment of MS. Expert opinion: Natalizumab is a very effective therapy for MS and has shown tremendous results in reducing the disease activity and improving patients' quality of life. Serious adverse effect such as PML warrant extreme caution and heightened clinical vigilance while prescribing the drug. If used with prudence, the drug can be instrumental in treatment of patients with inadequate response to the first-line medications.