This application represents a continued examination of the requirements for eradication of disseminated tumors by the adoptive transfer of tumor-specific T cells. Studies from our laboratory have demonstrated in murine models that T cell clones specific for tumor antigens can be generated and expanded in vitro for use in adoptive therapy, and that both non-cytolytic CD4+ and cytolytic CD8+ T cells can mediate complete elimination of disseminated tumors independent of contributions by the other subset. Many laboratories are now attempting to similarly expand T cells reactive with human tumors to treat cancer patients, but several significant obstacles have been identified. These include requirements for transferred T cells to survive, persist, and selectively home to sites of tumor; and determining if tumor-associated antigens detected in abundance on tumor cells but also found in limited amounts on some normal tissues represent appropriate antigens to pursue as targets for T cell therapy. The proposed studies will use two new molecular techniques to modify the conditions in murine tumor therapy models that have been developed and characterized in our laboratory as a means for gaining insights into how to overcome some of these obstacles. Retroviral-mediated gene transfer represents a promising method to introduce genes into T cells, which we propose to use to modify T cell function and phenotype for enhancing the therapeutic efficacy and safety of adoptively transferred T cells. Additionally, the technology for producing transgenic (TG) mice has provided new methods for examining issues of tolerance and autoimmunity, and we have developed several founder TG mice that express previously defined unique tumor-specific antigens in normal host tissues under the control of tissue-specific promoters. The proposed experiments will determine if: a.Cytolytic tumor-specific CD8+ T cell clones can be rendered more effective in tumor therapy by inducing regulated endogenous IL2 production through introduction of the genes for the IL1R and/or IL2. b.The therapeutic efficacy of T cell clones which lack expression of the gp9OMELl4 lymph node homing receptor can be enhanced by introducing the gp9OMELl4 gene. c.Introduction of an inducible "suicide gene" such as HSV-thymidine kinase can provide a means to eliminate T cell clones after adoptive transfer. d. The expression of a tumor antigen on peripheral tissues in TG mice, including tissues with low endogenous MHC expression, interferes with the efficacy of adoptive tumor therapy with T cells specific for the tumor antigen and/or becomes a target for autoimmune injury. e. A "suicide gene" can be used to eliminate transferred tumor-reactive T cell clones that are inducing autoimmune injury in TG mice expressing the target tumor-associated antigens normal tissues. f. T cells specific for a tumor antigen can be elicited in TG hosts also expressing that antigen in normal tissues.
NIH ExPorter
NIH ExPorter