The overall goal of this project is to provide an analysis of the effectiveness of gene modified tumor (GMT) vaccines using objective markers of immune stimulation. Characterization of the mononuclear cells that mediate the anti-tumor effects elicited by interferon gamma (INFgamma)GMT vaccines will be important to determine the mechanism of tumor rejection in humans, but may also be critical to clinically monitor the response to vaccines. Currently, the clinical parameters that can be monitored in human subjects receiving GMT vaccines are 1. delayed type hypersensitivity (DTH)) reactions; 2. regression or stability of clinically measurable disease; and 3. survival. In the patients with metastatic disease and heavy tumor burdens likely to initially receive GMT vaccines, these clinical endpoints may lack the sensitivity to document an effective anti-tumor immune response. Therefore, other parameters of an effective anti-tumor immune response elicited by the GMT vaccine are necessary. The immunologic requirements for a successful vaccination appear to include the generation of both cytotoxic T lymphocytes (CTL) and T helper cells (TH) and the detection of these cells by phenotypic and functional analysis remains a cornerstone of immunologic evaluation. Examples of in vitro tests which may be used to detect a specific active immune response include testing peripheral blood mononuclear cells (PBMC) for CTL and YH effector and memory function in response to antigen expressing cells or purified antigen. Alternatives to the detection of tumor specific immune responses in PBMC are required if a specific antigen is unavailable, and may include the detection of markers of antigen specific T cells in the circulation or infiltrating the tumors following GMT vaccination. Although no specific markers for melanoma specific T cells exist, characteristics such as phenotype, cytokine production and restricted T cell receptor (TCR) variable (V) gene usage may serve as indicators of activated and expanded subpopulations of T cells and reflect tumor specific immune responses. We hypothesize that an expansion of populations of T cells with restricted TCR V gene rearrangements will correlate with in vitro tests of CTL and TH and prove to be a surrogate marker for a GMT specific immune response in patients with metastatic melanoma. This characteristic can then be utilized as a surrogate marker for the effectiveness of active immunotherapy in humans and allow putative anti- tumor vaccine strategies to be evaluated and compared.
The specific aims of this study include:
Aim 1. Compare TIL and PBMC Before and After IFNgamma Gene Modified Tumor (GMT) Vaccination by Phenotypic Analysis.
Aim 2. Compare T Cell Receptor (TCR) Variable (V) Gene Analysis of TIL and PBMC.
Aim 3. Characterization of Cytotoxic T Cell (CTL) Response in TCR V Gene Restricted TIL and PBMC.
Aim 4. Characterization of T Helper Cell (TH) Response in TCR V Gene Restricted TIL and PBMC.
Aim 5. Correlation of Laboratory Findings With Clinical Parameters of Melanoma Specific Immune Response.
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