Spanish consensus on the use of natalizumab (Tysabri(®))--2011

Natalizumab is very effective at reducing relapses and delaying disease progression in patients with relapsing-remitting multiple sclerosis (RRMS). However, treatment has also been associated with a risk of progressive multifocal leukoencephalopathy (PML). The aim of this article is to provide a consensus view on the assessment and stratification of these risks, and to improve the management of natalizumab-treated patients.

At an initial meeting of experts on multiple sclerosis (the authors of this consensus), the relevant topics of the consensus were determined and assigned for further elaboration. Topics included how to establish benefit and risk in general, stratification for risk of PML, informing patients of benefits/risks, and how to monitor patients during treatment and after discontinuing treatment. During the drafting phase, all available information published or presented at international meetings was reviewed. After a series of review sessions and meetings, the final draft was produced.

Although natalizumab is a very effective drug, its use needs to be considered carefully in view of possible adverse effects and the risk of PML in particular. The neurologist should carefully explain the risks and benefits of treatment in terms the patient can best understand. Before starting treatment, baseline laboratory tests and magnetic resonance imaging (MRI) should be available for future comparisons in the event of suspected PML. The risk of PML should be stratified into high, medium and low risk groups according to presence or absence of anti-JC virus antibodies, prior immunosuppressive therapy, and treatment duration. The follow-up, and frequency of MRI scans in particular, should depend on the risk group to which patient belongs. As our understanding of the risk factors for PML develops, it should be possible to offer patients increasingly individualised therapy. This is a consensus that establishes general recommendations, but neurologists must use their clinical expertise to monitor patients individually.