Management approach including pembrolizumab for fingolimod-associated progressive multifocal leukoencephalopathy in a patient with relapsing-remitting multiple sclerosis.

A 62-year-old man with relapsing-remitting multiple sclerosis developed progressive multifocal leukencephalopathy (PML) after 6 years on fingolimod. The fingolimod was immediately discontinued and preexisting mirtazepine increased. Three weeks later, with brain magnetic resonance imaging (MRI) appearances worsening and cerebrospinal fluid (CSF) JC virus (JCV) titres increasing, maraviroc was introduced.