IMMUNO GENE THERAPY OF COLON CANCER

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DESCRIPTION: (Applicant's Description) The objective of this proposal is to translate encouraging pre-clinical results of novel immuno-gene therapies of colon carcinoma into the clinical setting and to further our understanding of immunostimulatory and immunosuppressive factors which may affect host anti-tumor immune responses against known and novel tumor associated antigens (TAAs). We plan to examine the effects of three different types of genetic manipulations to enhance the efficacy of therapeutic tumor cell vaccines: 1) Gene transfer of the immunostimulatory cytokine IL-2; 2) Inhibition of the immunosuppressive factor TGF-b by an antisense vector; and 3) Expression of the co-stimulatory molecule B7.1-CD80. We have recently initiated the proposed clinical analyses in the setting of the first RAC/FDA approved Phase I trial in colon carcinoma of active tumor immunotherapy with IL-2 transduced cells. In this trial, patients are immunized with autologous, irradiated tumor cells mixed with autologous IL-2 transduced fibroblasts. Practical considerations mandate the exploration of allogeneic cells for tumor immunotherapy which is supported by the recent identification of shared MUC-1, GA733 ) and MAGE TAAs expressed by many colon tumors and the tumor cell lines we will employ in our clinical trials. We plan to follow our initial trial using autologous cells with a trial employing allogeneic tumor cells and allogeneic IL-2 transduced fibroblasts. Subsequent trials will examine the effects of genetically modifying the allogeneic tumor cells to inhibit TGF-b and to express B7.1 in combination will IL2 transduced fibroblasts. The different vaccine preparations will be compared with respect to the generation of anti-tumor immune and clinical responses. Patients' peripheral blood and vaccination site mononuclear cells and derived cytotoxic T cell (CTL) clones will be utilized in cytotoxicity assays against panels of tumor cells and HLA matched fibroblasts transduced with known TAA genes to identify immune responses directed against known TAAS. RNA fingerprinting "differential display" techniques comparing tumor cells sensitive and insensitive to cell mediated cytotoxicity will be utilized to identify novel TAA genes. The information obtained from these studies will identify practical, genetically modified allogeneic tumor vaccines suitable for further evaluation in clinical trials and further our understanding of the relationships between immunostimulatory and immunosuppressive factors in generating anti-tumor immunity against known and novel TAAS.