REGULATION OF ANTI-TUMOR IMMUNITY

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The Program on "Regulation of Tumor Immunity" brings together investigators from the Department of Microbiology and Immunology, the Division of Hematology and Oncology in the Department of Medicine and the Department of Pathology to work together on the pressing problem of bringing Immunotherapy to a point where it can make an important contribution to patient care and treatment. The long-range goal of the program is to find ways to treat tumors with the aid of immunotherapy in the form of anti tumor vaccines. In order to develop successful immunotherapy it is necessary to define the parameters that allow the generation of anti tumor immunity and allow the maintenance of anti tumor effector functions over prolonged periods of time. Maintaining anti tumor effector responses over time necessitates our understanding of memory formation and maintenance. One important goal of the program in several projects is the elucidation of molecular mechanisms able to generate and maintain memory in the presence of established tumors. Anti tumor immunity requires TH1 polarization of the immune response. To the extent that TH2 and TH1 polarization are mutually antagonistic we suggest that elimination of TH2 responses may be beneficial for anti tumor therapy. B cells are the final effectors of TH2 polarization and we have shown that their elimination allows increased anti tumor activity. A second goal of the program examined in several projects therefore is the analysis of the mechanisms of anti tumor immunity in the absence of B cells. These studies are also aimed at the discovery of molecular pathways by which B cells dampen the anti tumor TH1 response. Our own studies and those by others support the hypothesis that the activation of the innate immune response is important for the generation of a powerful adaptive response and the generation of memory. The third goal of the program pursued therefore is the analysis of the contribution of NK cells and DC to anti tumor immunity. Since we have shown that heat shock proteins secreted by tumor cells activate DC, NK and CDS CTL this mode of activation will be studied in all projects and examined with regard to memory formation, generation of immunity in autologous bone marrow transplantation and in its effects under conditions of B cell depletion. Finally, a heat shock protein based vaccine will be used to test the hypothesis that non-immunogenic tumors are the best targets for vaccine-based immunotherapy. A phase I trial for non-small cell lung carcinoma patients will examine generation of an immune response and clinical benefit.