Successful Management of Natalizumab-Associated Progressive Multifocal Leukoencephalopathy and Immune Reconstitution Syndrome in a Patient With Multiple Sclerosis

Objective: To describe a case of successful clinical management of natalizumab-associated progressive multifocal leukoencephalopathy (PML) and immune reconstitution syndrome (IRIS) in a patient with multiple sclerosis. Design: Case report. Setting: University hospital. Patient: A 41-year-old woman with relapsing-remitting multiple sclerosis developed PML after 29 natalizumab infusions. Interventions: Immediate plasma exchange was combined for removal of natalizumab with application of mefloquine and mirtazapine to limit viral replication and oligodendrocyte infection. A subsequent IRIS was treated with glucocorticosteroids. Results: After 3 months of treatment, cerebrospinal fluid tested negative for JC virus. There was a favorable outcome, and the Expanded Disability Status Scale score remained stable at 3.5 compared with before PML. Conclusions: In the setting of early diagnosis and consequent treatment, natalizumab-associated PML can be well managed in some cases. This situation differs from the course of PML in other conditions, eg, after the application of depleting monoclonal antibodies, in which irreversible cellular effects are associated with very high mortality.