Antibody therapy in acute myeloid leukemia: current status and future directions

Monoclonal antibodies have become an important modality for cancer therapy. The genetically engineered, humanized anti-CD33 antibody HuM195 has demonstrated modest activity against overt relapsed acute myeloid leukemia (AML) and more substantial activity against minimal residual disease in acute promyelocytic leukemia. Radioimmunotherpay with beta-particle-emitting isotopes has eliminated large leukemic burdens while minimizing radiation exposure to normal tissues in both nonmyeloablative and myeloablative regimens. Targeted beta-particle immunotherapy with agents such as bismuth 213-labeled HuM195 offers the possibility of a more selective tumor cell kill with less damage to surrounding normal cells. Directed chemotherapy using the anti-CD33-calicheamicin conjugate gemtuzumab ozogamicin (Mylotarg) has produced remissions in patients with relapsed AML.