PD-1 inhibition: a novel approach to the treatment of progressive multifocal leukoencephalopathy

Joseph R. Berger


Progressive multifocal leukoencephalopathy (PML), a demyelinating disease of the brain due to an ubiquitous polyoma virus, JC virus, was first recognized in 1958 (1). PML was initially described in individuals with B cell malignancies, chronic lymphocytic leukemia and Hodgkins lymphoma, though it occurred with other predisposing illnesses as well.