Abstract LB052: HIF1α-driven glycolysis in hypoxic T cells modulates cytokine production and immunotherapy responses

Abstract Other than the few T cells residing in the upper airways, most T cells live in hypoxia that shapes their survival and functions. Although it has long been known that HIF1α is the primary regulator of cellular adaptive responses to hypoxia, whether and how HIF1α regulates cell survival and effector functions (i.e., cytokine production) in hypoxic T cells have been poorly defined. Combining genetic mouse models, metabolic flux using 13C-labeled glucose tracer, and measurement of cellular metabolic function by Seahorse analyzer, we show that the HIF1α-dependent glycolysis drives IFN-γ but suppresses IL-2 production in T cells under hypoxia, cytokines associated with late and early stages of T cell activation, respectively. Specifically, HIF1α deletion in T cells (Hif1α -/-) and glycolytic inhibition with 2-DG suppresses IFN-γ but promotes IL-2 production. In contrast, HIF1α stabilization by hypoxia and VHL deletion in T cells (Vhl -/-) increases IFN-γ but reduces IL-2. Hypoxic Hif1α -/- T cells and T cells treated with 2-DG survive better. Despite this, Hif1α -/- T cells are less able to kill tumor cells in vitro, and Hif1α -/- mice bearing established tumors are not responsive to immune checkpoint blockers (ICB) (combined anti-CTLA-4 and anti-PD-1) in vivo, in line with their drastically reduced production of IFN-γ. Mechanistically, HIF1α deficiency diminishes glycolytic activity in hypoxic T cells, resulting in depleted intracellular acetyl-CoA. Restoration of intracellular acetyl-CoA by acetate supplementation rescues IFN-γ production in hypoxic Hif1α -/- T cells and re-sensitizes Hif1α -/- tumor-bearing mice to ICB. Taken together, HIF1α-dependent glycolysis reciprocally regulates the production of early (IL-2) and late effector cytokines (IFN-γ) as well as survival of hypoxic T cells, representing a key T cell-intrinsic metabolic checkpoint of ICB responses. Citation Format: Vivian Y. Shi, Hongxing Shen. HIF1α-driven glycolysis in hypoxic T cells modulates cytokine production and immunotherapy responses [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB052.