Pembrolizumab Treatment for Progressive Multifocal Leukoencephalopathy

Our findings are consistent with the hypothesis that in some patients with PML, pembrolizumab reduces JC viral load and increases CD4+ and CD8+ activity against the JC virus; clinical improvement or stabilization occurred in five of the eight patients who received pembrolizumab. Further study of immune checkpoint inhibitors in the treatment of PML is warranted. (Funded by the National Institutes of Health.).