Does Rituximab Have a Place in Treating Classic Hodgkin Lymphoma?

Monoclonal antibodies targeting surface proteins on the malignant Hodgkin and Reed-Sternberg (HRS) cells are currently under intensive investigation with promising early results. Of particular interest is the CD20 antigen, because it is expressed not only on a small fraction of HRS cells but also on the benign reactive B cells in the microenvironment. The rationale of using rituximab in classic Hodgkin lymphoma (cHL) comprises several points: 1) HRS cells infrequently express CD20; 2) elimination of CD20-positive reactive B cells supporting HRS cells would deprive the malignant cells of survival signals; 3) elimination of reactive B cells may also potentially increase host immune response against HRS cells; 4) HRS stem cells express CD20. Although this rationale has not generally been confirmed in patients, promising results in managing cHL have occurred in early-phase clinical trials of rituximab, including trials of rituximab as a single agent in refractory or recurrent cHL, rituximab plus gemcitabine in refractory or recurrent cHL, and rituximab plus ABVD in newly diagnosed cHL. Based on the results of these trials, several prospective clinical trials using rituximab in the management of advanced-stage cHL and early-stage cHL are ongoing. These trials further clarify the role of rituximab in cHL. Enrollment of patients with this "classic" disease in clinical trials is encouraged.