{'fraction_non_alphanumeric': 0.034887860448558204, 'fraction_numerical': 0.018867924528301886, 'mean_word_length': 5.162280701754386, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Abstract A10: Constitutive HIF activity enhances T-cell antitumor immunity and memory T-cell formation in the murine adoptive cell therapy model

Purpose: To determine if unrestrained hypoxia inducible factor (HIF) activity in CD8 T cells improves antitumor response. Methods: CD8 T cells were isolated from von Hippel Lindau (VHL)-deficient (VHL KO) mice, which have unrepressed HIF1 and HIF2 activity, as well as from VHL/HIF1/HIF2 triple-deficient (TKO) and WT mice. Following in vitro activation, T cells were transferred to melanoma (B16) tumor-bearing mice and monitored for tumor progression and survival. In other studies, activated VHL KO and TKO CD8 cells were mixed with WT CD8 cells and transferred to B16 or adenocarcinoma (MC38) tumor-bearing mice; after 7-10 days, donor T cells were analyzed from tumors, spleens, and draining lymph nodes (LN). Results: Single transfer of VHL KO CD8 T cells to B16 tumor-bearing mice resulted in delayed tumor growth and prolonged survival compared to transfer of CD8 T cells from TKO or WT donors. Co-transfer of VHL KO cells with WT cells into B16 tumor-bearing mice resulted in superior accumulation of VHL KO cells in all tissues including tumors. In contrast, mixed transfer of TKO cells with WT cells to B16 tumor-bearing mice resulted in poorer accumulation of TKO cells in all tissues including tumors. VHL KO tumor-infiltrating lymphocytes (TILs) had superior expression of tissue resident memory (TRM) phenotype markers CD103 and CD69 compared to WT and TKO TILs. Similarly in the MC38 tumor model, VHL KO cells showed improved accumulation in all tissues compared to WT cells. Conclusions: Here we demonstrate that VHL deletion in CD8 T cells results in superior efficacy in delaying tumor growth and improving recipient survival, greater accumulation in multiple solid tumor models, and increased development of the TRM phenotype. Further, TKO recipients demonstrated increased tumor growth, reduced survival, reduced TIL numbers, and absence of TRM phenotype following adoptive transfer, confirming the HIF dependency of the VHL-deletion phenotype. Taken together, these data demonstrate that T cells with constitutive HIF activity provide a more robust antitumor response. Therefore, manipulation of HIF regulation could offer new tools for enhanced T-cell efficacy in adoptive cellular therapy for solid tumors. Citation Format: Colette R. Lauhan, Deborah Witherden, Ilkka Liikanan, Ananda Goldrath. Constitutive HIF activity enhances T-cell antitumor immunity and memory T-cell formation in the murine adoptive cell therapy model [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr A10.