BACKGROUND: The use of monoclonal antibodies to deliver radioactive isotopes directly to tumor cells has become a promising strategy to enhance the antitumor effects of native monoclonal antibodies. In this article, we summarize the role of radioimmunotherapy in the treatment of leukemia. METHODS: The authors reviewed the published clinical trials of radioimmunotherapy in acute leukemia. RESULTS: Radioimmunoconjugates that emit beta-particles, such as 131I-anti-CD33, 90Y-anti-CD33, 131I-anti-CD45, and 188Re-anti-CD66c, deliver significant doses of radiation to the bone marrow and may be particularly effective when used as part of a conditioning regimen for hematopoietic stem cell transplantation. Radioimmunoconjugates that emit short-ranged alpha-particles, such as 213Bi-anti-CD33, are better suited for the treatment of low-volume or residual disease. CONCLUSIONS: Radiolabeled antibodies can be administered safely to patients with advanced leukemias and have significant antileukemic activity. Radiolabeled antibodies can potentially intensify the antileukemic effects of conditioning regimens when used in conjunction with hematopoietic stem cell transplantation. Whether or not radiolabeled antibodies improve the outcome of patients with leukemia remains to be demonstrated by randomized studies.
