In active specific immunotherapy for human cancer, the vehicle for immunogenic stimulus, or the vaccine, has comprised tumor cells themselves, in one form or another. Tumor cells, however, might not be able to provide the antigenic and the co-stimulatory signals, two obligate necessities for T cell activation. In a search for a more effective vehicle for delivery of both signals, we seek to use the macrophage, a professional antigen presenting cell, to develop an autologous macrophage-based melanoma vaccine. Melanoma is an ideal tumor because it is an immunogenic tumor and the melanoma antigen gene has been structurally defined and the antigenic peptide sequenced. Accordingly, we propose to test the hypothesis that the state of immunologic unresponsiveness of hosts against autologous melanomas can be broken through a novel approach using active specific immunotherapy. The approach will incorporate a mechanism of delivery of the antigenic as well as the co-stimulatory signals, simultaneously, through various routes. Autologous macrophages will be pulsed with relevant tumor antigen derived peptides, or made to take up, process and present tumor associated antigens, or made to present the tumor antigen derived peptide following the introduction of the gene encoding the antigen into such APC by in vitro gene transfer technique. For this purpose, large numbers of macrophages will be grown from melanoma patients, and the cultured macrophages will be pulsed with the melanoma antigen (MAGE-1) peptide EADPTGHSY or will be loaded (through phagocytosis or endocytosis) with the autologous melanoma lysates for processing and presenting of antigen fragments on their MHC molecules. Patients, who are at risk for recurrence or who have recurrent disease and who are HLA A1/MAGE1 positive, will be vaccinated with the peptide pulsed Mphi. Other patients will be treated with autologous Mphi loaded with lysates of autologous melanomas as sources for melanoma associated protein antigen. All patients will be first primed, intravenously, with the peptide pulsed or the antigen loaded Mphi, followed by four intradermal challenge doses. A method of skin testing with the antigen or the vaccine will be developed to assess the immunogenicity of the vaccine. In addition, extensive laboratory evaluation of the immune status of the vaccinated patients will be undertaken to answer the question of whether or not this type of immunization can induce a T cell mediated response in vivo. T cells isolated from immunization sites, skin test sites and from metastatic deposits will be expanded in vitro and cloned for detailed phenotypic and functional analyses (proliferative and cytokine synthetic ability upon stimulation with the immunogen, cytolytic capacity against the autologous and other targets). Finally, we shall explore the feasibility of transferring the MAGE-1 gene along with the co-stimulatory molecule B7 into Mphi by in vitro gene transfer technique for future in vivo testing of such genetically altered Mphi vaccine. Results of in vitro assays for immunogenicity, skin testing and therapeutic result, if any, will be analyzed to establish clinical correlates. These studies will facilitate the development of a unique and effective form of specific biologic cancer therapy.
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