Final Report Summary - ANTITUMOR IMMUNITY (An in-vivo RNAi approach to identify and evaluate suppressors of anti-tumor T cell immunity)
Here, we aimed at systematically identifying and functionally exploring new key players in the suppression of T cell anti-tumor immunity using an innovative approach by combining well-established genetically engineered mouse models (GEMMs) of human cancer, T cell receptor (TCR) / cognate antigen transgenic systems, and state-of-the-art in vivo RNAi technologies. To systematically probe the biology of dysfunctional anti-tumor T cell responses and explore candidate targets for the development of immune-modulatory therapies we established scalable experimental in vivo systems for screening and evaluating genes involved in the suppression of anti-tumor T cell responses in a model of acute myeloid leukemia (AML) and in a model of pancreatic ductal adenocarcinoma (PDAC). In brief, we generated T cell focused candidate shRNA libraries and probed them in multiplexed in vivo RNAi screens to systematically identify key genes involved in the suppression of anti-tumor T cell responses. We employed next generation sequencing to assess changes in the abundance of individual genetic elements (shRNA expression cassettes) in the context of an anti-tumor T cell response, and – after setting up a novel bioinformatic analysis pipeline – could identify both, already established as well as new modulators of T cell function. Furthermore, the dual setup of our approach allowed us to pinpoint common, as well as tumor type specific mediators of T cell dysfunction. We are currently following up on the function of these genes to evaluate their suitability as drug targets.
In sum, we have established a robust screening platform that allows multiplexed interrogation of gene function in the context of anti-tumor T cell immunity. With this we could identify genes that are involved in the functional suppression of tumor reactive CD8+ T cells in vivo, which may be exploited as novel drug targets.