Rituximab: perspective on single agent experience, and future directions in combination trials.

The chimeric anti-CD20 antibody rituximab is the first monoclonal antibody to gain regulatory approval for the treatment of any malignancy. As such, its development represents a major milestone in cancer therapy. It is an effective single agent for patients with CD20-positive B-cell malignancies, using a well-tolerated and brief (weekly x 4) schedule that has become the accepted standard. Since this weekly x 4 schedule is not a maximum tolerated dose, additional research is being done on different doses and schedules of rituximab. Researchers are also exploring the use of rituximab in conjunction with cytokines or chemotherapy. Further developments in the use of rituximab and other targeted therapy approaches can be expected as we learn more about the mechanisms of action of, and resistance to, rituximab.