Abstract 2868: A chemogenetic approach reveals a GPCR-Gαs-PKA signaling axis promoting T cell dysfunction and cancer immunotherapy failure
Authors: Yung Bryan S. , Wu Victoria H. , Faraji Farhoud , Saddawi-Konefka Robert , Wang Zhiyong , Wenzel Alexander T. , Song Miranda , Pagadala Meghana S. , Clubb Lauren M. , Chiou Joshua , Sinha Sanju , Matic Marin , Raimondi Francesco , Hoang Thomas , Berdeaux Rebecca , Vignali Dario A. , Iglesias-Bartolome Ramiro , Carter Hannah , Ruppin Eytan , Mesirov Jill P. , Gutkind J. Silvio 
Published: June 2023

Abstract
Recent advances in immune checkpoint blockade (ICB) inhibiting programmed death-1 (PD-1) and cytotoxic T-lymphocyte-associated protein (CTLA-4) have revolutionized the standard of care for cancer treatment. However, the limited response rates to ICB across multiple cancer types suggest that new approaches and targets are clearly needed to fully elucidate the underlying biology of dysfunctional and exhausted CD8 T cells in cancer in order to achieve durable responses (cure). G protein-coupled receptors (GPCRs) are the most intensively studied drug targets, primarily due to their druggability and relevance to most physiological processes and disease conditions. However, the role of GPCRs in cancer and particularly in cancer immunology has been largely underexplored. We have applied a new computational pipeline to cross-integrate hundreds of thousands of CD8 T cells from multiple single cell RNA-seq datasets from 13 distinct cancer types. Using this approach, we identified many GPCRs that are overrepresented in exhausted CD8 T cells. A new computational strategy enabled us to predict the G protein coupling specificity of most GPCRs. This led to the discovery that Gαs-coupled GPCRs are significantly enriched in exhausted CD8 T cells. These include EP2, EP4, A2AR, β1AR, and β2AR, and we found that all of these receptors promote CD8 T cell dysfunction by inhibiting cytotoxicity and cytokine secretion. However, these receptors are also expressed in other immune cells within the tumor microenvironment. To address the direct impact of these receptors on T cell function we used a novel synthetic biology approach, involving the development of a chemogenetic CD8-restricted Gαs-DREADD (Designer Receptor Exclusively Activated by A Designer Drug) transgenic mouse model in which activation of Gαs signaling is temporally and spatially controlled. Utilizing this Gαs-DREADD model, we discovered that the Gαs-signaling axis represents a previously uncharacterized signaling axis that dampens the anti-tumor CD8 T cell activity and leads to ICB immunotherapy failure. Our central hypothesis is that secretion of GPCR ligands in the tumor microenvironment and their actions on CD8 T cells lead to the activation of the Gαs signaling cascade leading to T cell dysfunction, by decreasing cytotoxic and migratory activity that abolished the effectiveness of ICB. Our findings reveal that Gαs-coupled GPCRs may represent new targetable immune checkpoints that can be combined with ICB as part of novel multimodal precision approaches to enhance the response to immunotherapies.
Citation Format: Bryan S. Yung, Victoria H. Wu, Farhoud Faraji, Robert Saddawi-Konefka, Zhiyong Wang, Alexander T. Wenzel, Miranda Song, Meghana S. Pagadala, Lauren M. Clubb, Joshua Chiou, Sanju Sinha, Marin Matic, Francesco Raimondi, Thomas Hoang, Rebecca Berdeaux, Dario A. Vignali, Ramiro Iglesias-Bartolome, Hannah Carter, Eytan Ruppin, Jill P. Mesirov, J. Silvio Gutkind. A chemogenetic approach reveals a GPCR-Gαs-PKA signaling axis promoting T cell dysfunction and cancer immunotherapy failure [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2868.