Emerging applications of gene transfer in the hematopoietic cancers

Purpose: Originally conceived as a means to replace or correct defective genes in patients with inherited disorders, gene transfer has shown broad potential for medical intervention in the hematopoietic cancers and for study of hematopoietic stem cell biology. The purpose of this article is to review emerging applications of gene therapy with special reference to hematopoietic neoplasia. Results: Gene transfer strategies now under investigation in the hematopoietic cancers focus on (a) repair of one or more genetic defects associated with the malignant process, (b) delivery of a prodrug-metabolizing enzyme that causes tumor cells to become sensitive to the corresponding anticancer drug, (c) modification of immune responses to the cancer, or (d) introduction of drug resistance genes to increase the therapeutic index of cytotoxic agents. Finally, by marking normal or malignant cells with readily detectable genes, one can monitor the efficacy of therapy or study the dynamics of stem cell behavior in vivo. Conclusion: Despite their undisputed contributions to our knowledge of the hematopoietic cancers, gene transfer studies have been limited by the quality of vector technologies. As transduction efficiencies and gene regulatory mechanisms improve, gene transfer can be expected to evolve into a major therapeutic modality in its own right.