Sievers EL. Clinical studies of new "biologic" approaches to therapy of acute myeloid leukemia with monoclonal antibodies and immunoconjugates.
Curr Opin Oncol 2000;
12:30-5. [PMID:
10687726 DOI:
10.1097/00001622-200001000-00005]
[Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Conventional chemotherapeutic treatments of acute leukemias are often associated with life-threatening toxic effects due to a lack of specificity for hematopoietic cells. Monoclonal antibodies and fusion proteins that target antigens on leukemic blasts are being explored for their antileukemic effects and as a means of delivering chemotherapy or radiation directly to malignant cells. This approach might be safer and more effective than current non-specific chemotherapeutic agents. The cell surface antigens CD33 and CD45 are attractive targets. Although CD33 is expressed on acute myelocytic leukemic blast cells from about 90% of patients, normal hematopoietic stem cells lack this antigen, as do essentially all non-hematopoietic tissues. Anti-CD33 antibodies have been engineered to selectively target malignant myeloid and immature normal cells while sparing normal stem cells. Recently, anti-CD33 antibodies have also been used to deliver radiation or a cytotoxic agent directly to leukemic cells. The strategy for using CD45 as a target differs from CD33 in that it is expressed not only by the vast majority of leukemias, but also by normal stem cells. Therefore, 131I-labeled anti-CD45 antibody has been used in combination with conventional preparative regimens for patients receiving marrow transplantation for acute leukemia. Because the receptor for granulocyte-macrophage colony-stimulating factor is expressed by most myeloid leukemias, fusion proteins consisting of granulocyte-macrophage colony-stimulating factor ligand associated with diphtheria toxin have been proposed as a means of delivering a toxic agent directly to leukemic cells. Both unconjugated and conjugated antibodies show significant promise in the treatment of acute myelocytic leukemia.
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