Protective antitumor immunity to murine tumors can be induced by immunization strategies designed to make tumor antigens more immunogenic. Promising results have been obtained using gene transfer in preclinical studies through: the use of ex vivo gene modified tumor cells, which express immunostimulatory cytokines such as GM-CSF; the use of in vivo modified tumor cells treated to express stimulatory molecules such as foreign MHC antigens or IL-12; and with direct immunization using genes controlling immunogenic peptides inserted into antigen presenting tissues such as skin or dendritic cells. Each of these approaches is now being tested in clinical trials. We have pursued preclinical development of particle mediated gene transfer (PMGT), which is a gene transfer technology using 2 micro gold beads, where each bead carries over 10,000 copies of the desired transgene on a non-infectious expression vector. Efficient DNA delivery occurs in each cell receiving a gold bead, and transfection in vitro or in vivo is rapid, technically simple, and would be clinically expedient. Our preclinical data document the efficacy and immunologic advantage of PMGT in ex vivo, and purified antigen gene delivery model systems for tumor immune reactions. These concepts and this technology are now ready for clinical testing. We thus propose four years of integrated clinical and laboratory research to be performed through this CATBRM mechanism. Specifically, we will: 1) Perform four Phase I/IB clinical trials of PMGT, testing the safety, biologic and immunologic efficacy, and anti-tumor potential of three distinct cancer immunization approaches designed to initiate systemic anti-tumor immunity. These four protocols are: A-1: Immunization with melanoma and sarcoma cells transfected ex vivo with the GM-CSF gene by PMGT; A-2: Immunization by in vivo PMGT to the tumor vaccination site with the GM-CSF gene; B: Immunization by in vivo PMGT with the IL-12 gene to the peri-tumor epidermis; C: PMGT to normal epidermis, combining genes for the MART-1 antigen; the B7.1 co-stimulatory molecule, and IFN-gamma. 2) For each protocol: a) perform detailed clinical evaluations of local and systemic toxicity; b) assay gene transfection sites and tumor sites for transgene expression and local immune responses; c) assay blood specimens for systemic gene expression and immune responses; and d) determine anti-tumor effects in each patient. 3) Analyze all clinical and laboratory results to compare each regimen for induction of anti-tumor immunity, to determine the design for Phase II testing of these PMGT strategies, and determine how they may be modified or combined to obtain enhanced immunologic and anti-tumor effects.
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