Authors of a recent study evaluated inflammatory activity in multiple sclerosis patients who developed natalizumab-associated progressive multifocal leukoencephalopathy (PML) using translocator protein positron emission tomography (TSPO PET) for imaging of microglia. They demonstrated that TSPO PET can monitor PML longitudinally.
These authors evaluated the effect of pembrolizumab, a monoclonal antibody that functions as a down-regulator of PD-1 (programmed cell death protein 1), on patients with progressive multifocal leukoencephalopathy. In five of eight treated patients, clinical stabilization or improvement was seen in association with reduced cerebrospinal fluid JC viral load. This is the first reported effective treatment for this disease with a therapeutic agent targeting the JC virus.