Inclusion of Rituximab in Treatment Protocols for Non-Hodgkin's Lymphomas and Risk for Progressive Multifocal Leukoencephalopathy

Abstract

Objectives. Rituximab is an anti-CD20 monoclonal antibody that promotes better treatment outcomes in patients with non-Hodgkin's lymphoma (NHL). Case series of progressive multifocal leukoencephalopathy (PML) in patients receiving rituximab within polychemotherapy regimens have led to the introduction of a black box warning, but no risk estimation has ever been provided. Methods. We performed a retrospective, monocentric cohort study on 976 NHL patients diagnosed in 1994–2008, including 517 patients who received at least one dose of rituximab. Results. Inclusion of rituximab into standard chemotherapy regimens for NHL caused a significantly higher incidence of PML cases (rate difference, 2.2 every 1,000 patient-years; 95% confidence interval, 0.1–4.3). Interpretation. Based on this finding, clinical surveillance of PML-related symptoms is recommended in NHL patients exposed to rituximab.