Characteristics and outcomes of progressive multifocal leukoencephalopathy in hematologic malignancies and stem cell transplant – a case series

: Progressive multifocal leukoencephalopathy (PML) is a life-threatening opportunistic infection of immunomodulatory therapies. PML cases reported in PubMed (1995-2017) following stem-cell transplantation (HSCT) or chemoimmunotherapy (CIT) for hematologic malignancies were reviewed. We found 107 cases, 40% were HSCT recipients (32 allogeneic, 11 autologous) and 40% indolent lymphomas receiving monoclonal antibodies (mAbs). HSCT cases had longer time to PML diagnosis (10.8 vs. 4 months, p < .001), higher proportion of PML therapy response (58% vs. 25%, p = .019), lower mortality rate (56% vs. 88%, p < .001), and longer median survival (8 vs. 2 months, p < .001). Outcome differences might be caused by selection bias as HSCT patients are most likely treated aggressively; however, time-dependent immune reconstitution might also contribute to their better prognosis. Increased use of mAbs and HSCT are associated with rising PML incidence in hematological malignancies, currently constituting the second largest vulnerable population after HIV-infected patients; further research is needed for its optimal treatment.