Rituximab in autologous stem cell transplantation for follicular lymphoma

Contamination of stem cell harvests with residual tumor cells is a significant problem hampering the success of autologous peripheral blood stem cell transplantation in non-Hodgkin's lymphoma (NHL). Techniques have therefore been introduced to attempt to remove these cells, either in vivo, prior to harvesting, or ex vivo, before reinfusion into the patient. Rituximab is a human-mouse chimeric anti-CD20 monoclonal antibody that has been administered to patients prior to stem cell harvesting, to purge the blood of residual malignant cells. Clinical studies have shown that rituximab is safe to use during stem cell mobilization since administration did not adversely affect the yield of CD34+ stem cells or the functional capability of these progenitors. Rituximab was also effective in purging stem cell harvests of malignant cells. Translocation of the bcl-2 gene was found in a significantly smaller proportion of stem cell harvests from patients who had received a purging infusion of rituximab than controls. Rituximab may also be useful as salvage therapy following post-transplant relapse or as maintenance therapy for patients in remission. Prospective randomized trials will ultimately define the role of rituximab in the autologous transplantation setting.