Treatment of Progressive Multifocal Leukoencephalopathy with Pembrolizumab

Abstract
A patient with variable immunodeficiency and progressive multifocal leukoencephalopathy was treated with five pembrolizumab infusions. The CSF JC viral load went from 119,000 copies per milliliter to undetectable levels. Neurologic signs stabilized, and the size of some white-matter lesions was reduced on MRI.