Evolving role of monoclonal antibodies in the treatment of chronic lymphocytic leukemia.

Recognition of cancer-specific antigens resulted in development of monoclonal antibodies as treatments for various neoplasms including chronic lymphocytic leukemia (CLL). Two monoclonal antibodies, alemtuzumab and rituximab, have been extensively studied, as monotherapy or in combination, in patients with various clinical stages of CLL. Alemtuzumab, particularly when combined with fludarabine-based chemotherapy, sequentially or concomitantly, represents a promising therapeutic approach that results in improved efficacy by further reducing levels of residual disease in previously untreated or relapsed/refractory CLL. On the other hand, single-agent rituximab has limited activity by itself, even at very high doses, and seldom induces complete remissions. However, rituximab is feasible to combine with conventional chemotherapies such as purine analogs, alkylating chemotherapy and/or alemtuzumab. Newer monoclonal antibodies are already showing activity in relapsed/refractory CLL and will eventually be evaluated in combinations with conventional chemotherapy, or with already established antibodies. Modern definitions for assessment of responses such as minimal residual disease negativity (MRD negativity) are emerging and, consequently, development of assays capable of measuring such responses. MRD negativity should become the primary objective of clinical trials when evaluating treatment interventions in patients with CLL. The future of monoclonal antibodies for treatment of CLL is bright.