T cells represent critical immunologic effectors in the anti-tumor immune response produced by therapeutic cancer vaccines. The investigators participating in this NCDDG grant have all been involved in utilizing current molecular technology to develop novel approaches for inducing T cell-mediated anti-tumor immune responses. In addition, they recently identified a new candidate tumor antigen that is overexpressed by the majority of pancreatic and ovarian cancers. Mesothelin is one of a large category of identified tumor-associated, non-mutated self-antigens which is overexpressed by tumor cells relative to normal tissue. Although there are examples of the induction of T cell responses against this category of antigens, including mesothelin, currently employed vaccine approaches are not potent enough to overcome the mechanisms of peripheral tolerance that occur to these self-antigens. Therefore, it is necessary to utilize relevant animal models for identifying the most potent combinatorial vaccine approaches that can overcome natural mechanisms of peripheral tolerance, systemic and locally within the tumor's micro-environment, and thus be worthy of clinical testing. Drs. Jaffee and Wu are developing the reagents and testing mesothelin-targeted vaccine approaches, in two mesothelin-expressing, murine tumor models, a pancreatic and ovarian tumor model, respectively. Taking advantage of active scientific collaborations with Drs. Pardoll and Chen, which have been ongoing over the past 10 years, the NCDDG group now proposes to utilize these two mouse models to evaluate and develop more potent antigen-specific vaccine strategies combined with immune modulators in the form of biologics, that can overcome tolerance to tumor-associated self antigens. This development will follow a four step process: 1) Individual vaccine strategies under development by the NCDDG project leaders will be optimized for a number of parameters using transplantable pancreas and ovarian tumors. Each model provides unique opportunities to understand local T cell tolerance in the tumor's micro-environment. 2) Baseline immunologic effector functions will be measured as an additional parameter for identifying the most potent vaccine approaches. 3) Optimized vaccine approaches will then be compared head-to-head for the ability to eradicate naturally developing hepatic metastases (pancreatic tumor model) and peritoneal metastases (ovarian tumor model). 4) Based on data from the in vivo studies and the measured immune parameters, a targeted evaluation of potential synergies between different vaccine strategies will be evaluated using potency against hepatic pancreatic tumor metastases and peritoneal ovarian tumor metastases as the final outcome.
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