Abstract 3970: Impairment of tumor reactive CD8 T cells in liver cancer

Abstract Tumor reactive (TR) CD8 T cells in the liver have been studied in the setting of both immunotherapy and cellular therapy with the predominant dogma that these cells have equivalent functionality in the liver as compared to other organ sites. Herein, we detail that TR+ CD8 T cells are functionally impaired in the liver immune microenvironment in mice with liver tumors.TR+ CD8 T cells were studied in BALB/c and C57BL/6 mice injected intrahepatic, intravenous, and subcutaneously with either a colon (CT26) or a melanoma (B16F10) cancer cell line to create intrahepatic, pulmonary and subcutaneous tumors, respectively. Additionally, an ⍺CD8 antibody with IgG control was used to conduct functional studies. Samples were analyzed using flow cytometry and liver weights were measured. A high frequency of TR+ CD8 T cells were found in the liver in mice with intrahepatic tumors. Despite ~70% of CD8 T cells being tumor reactive in intrahepatic tumors, liver tumor growth kinetics were faster than subcutaneous tumors. Higher proportion of the TR+ CD8 T cells were found to be exhausted in the liver tumor by flow cytometry. Functional depletion of the CD8 T cells caused a fivefold higher tumor growth in the subcutaneous model but in contrast had no effect on intrahepatic tumors. In conclusion, despite the high frequency of “killer” tumor reactive T cells in the liver, the growth kinetics of the liver tumors, flow cytometry as well as functional studies demonstrate the impairment of TR+ CD8 T cells in the liver. We aim to dissect the mechanisms mediating intrahepatic TR CD8+ T cell exhaustion in primary liver tumors as well as metastatic models. Additionally, we aim to determine significant costimulatory molecules specific to intrahepatic exhaustion which could lead to better therapeutic models. Citation Format: Rajiv S. Trehan, Marlaine Soliman, Xin Wang, Patrick Huang, Noemi Kedei, Xiao Bin Zhu, Matthias Seifert, Mohamed-Reda Benmebarek, Amran Nur, Firouzeh Korangy, Chi Ma, Tim F. Greten. Impairment of tumor reactive CD8 T cells in liver cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3970.