Loss of CD20 Expression after Rituximab Therapy for B-Cell Lymphomas: A Review of the Literature

Rituximab (Rx), a chimeric anti-human CD20 antibody, is used widely for the treatment of B-cell non-Hodgkin’s lymphomas (NHL) worldwide. Loss of CD20 expression in relapsed B-cell lymphomas after Rx treatment, however, is observed in some cases, which might be a cause of B-cell NHL unresponsiveness to Rx retreatment. The frequency of loss of CD20 expression after Rx treatment and radiotherapy, its correlation with histological changes, and its clinical implication together with possible molecular mechanisms are discussed in this review of pertinent literature. In high-grade B-cell NHL, loss of CD20 expression after Rx treatment was observed less frequently in Japan than in Australia. Evaluation of CD20 expression by immunohistochemical and flow cytometric methods is a reliable guide for employment of Rx treatment for B-cell lymphomas.