Late occurrence of progressive multifocal leukoencephalopathy after anti-CD19 chimeric antigen receptor T-cell therapy.

Progressive multifocal leukoencephalopathy (PML) is a life-threatening infection of the central nervous system in immunocompromised patients, with an established predilection in non-Hodgkin's lymphoma and stem cell transplant recipients. In the era of chimeric antigen receptor T-cell therapy (CAR T-cell), the occurrence of new-onset neurological symptoms and encephalopathy in this patient population can be attributed to a variety of factors, including therapy-related neurotoxicity or disease progression. PML has not been implicated as a common cause of encephalopathy in CAR T-cell therapy recipients, and the identification of such rare infections is important to guide prognosis and treatment decisions. We hereby report the first case of late occurrence of PML, over one year after CAR T-cell therapy, for a patient with relapsed large B-cell lymphoma.