Innovative therapeutic concepts of progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is an opportunistic viral disease of the brain—caused by human polyomavirus 2. It affects patients whose immune system is compromised by a corresponding underlying disease or by drugs. Patients with an underlying lymphoproliferative disease have the worst prognosis with a mortality rate of up to 90%. Several therapeutic strategies have been proposed but failed to show any benefit so far. Therefore, the primary therapeutic strategy aims to reconstitute the impaired immune system to generate an effective endogenous antiviral response. Recently, anti-PD-1 antibodies and application of allogeneic virus-specific T cells demonstrated promising effects on the outcome in individual PML patients. This article aims to provide a detailed overview of the literature with a focus on these two treatment approaches. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00415-021-10952-5.