Pharmacovigilance and PML in the oncology setting.

Methods developed by the Southern Network on Adverse Reactions project, the only state-funded pharmacovigilance program in the nation, are invaluable in identifying rare and serious drug events and in disseminating related safety reports quickly throughout the medical community. An important discovery was identification and reporting of an association of rituximab and progressive multifocal leukoencephalopathy (PML) in patients without human immunodeficiency virus (HIV). A recent investigation identified 57 patients with rituximab-associated PML, including bone marrow samples, brain biopsies, and autopsy materials from patients with lymphoma and PML who tested positive for JC virus. The investigation identified an association of rituximab-chemotherapy administration and PML, although a causal relationship remains an area of active investigation. Additional investigations evaluated the epidemiology of PML in the oncology setting before and after the introduction of rituximab for lymphoma treatment. Focused analyses investigated risk factors for development of this rare complication. Further studies are needed to investigate the pathophysiology, epidemiology, and risk factors for PML developing among HIV-negative cancer patients who receive rituximab and chemotherapy.