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Cancer Stem Cells as Targets for Anticancer Agents

Drugs directed at cancer-specific targets, such as imatinib mesylate in chronic myeloid leukemia, have the potential to favorably influence patient outcomes by decreasing toxicity and improving disease control. However, recent laboratory and clinical data raise questions about whether new anticancer agents will effectively target relevant subsets of cancer cells. In a commentary, Jones et al. (p. 583) discuss the biologic distinction between cancer stem cells—the rare population of cells that give rise to malignancies—and the differentiated cells that characterize the disease. They note that therapies that target mature cancer cells are unlikely to produce long-term remissions unless they also target the rare cancer stem cells responsible for maintaining the disease. They stress that the development of new anticancer treatments should take into account the pathogenesis and biology of the diseases being treated, and that survival, rather than response, should remain a primary endpoint of therapeutic efficacy in studies of such new treatments.