Cancer gene therapy utilizing interleukin-13 receptor alpha2 chain

Cancer cells are known to express cell surface molecules such as specific antigens or cytokine receptors, e.g., EGFR, Fas/CD95, gp100, HER-2/neu, IL-13Ralpha2, and MAGE. Among them, interleukin-13 receptor (IL-13R) alpha2 chain is expressed on certain types of cancer cells including glioblastoma, AIDS Kaposi's sarcoma, and head and neck cancer. This protein is one of the receptor components for IL-13, a Th2 cell-derived pleiotropic immune regulatory cytokine. IL-13Ralpha2 chain on these cancer cells can be targeted with a receptor-directed cytotoxin termed IL13-PE to induce specific cancer cell killing, however, this molecule does not mediate cytotoxicity to cells that do not express or express low levels of IL-13Ralpha2. In order to achieve a broad therapeutic window for IL13-PE, plasmid-mediated gene transfer of IL-13Ralpha2 in cancer cells was employed in vitro and in vivo. Cancer cells transfected with IL-13Ralpha2 demonstrated increased binding to IL-13 and sensitivity to IL13-PE in vitro. In vivo intratumoral gene transfer of IL-13Ralpha2 profoundly enhanced the antitumor activity of IL13-PE, providing complete elimination of established tumor in some xenografts. In this review article, current findings from IL-13Ralpha2 gene transfer in a variety of human cancer models in nude mice are summarized. In addition, safety issues and possible future directions utilizing this therapeutic approach are discussed.