Pharmacologic Screening Identifies Metabolic Vulnerabilities of CD8+ T Cells

Abstract

Metabolic constraints in the tumor microenvironment constitute a barrier to effective antitumor immunity and similarities in the metabolic properties of T cells and cancer cells impede the specific therapeutic targeting of metabolism in either population. To identify distinct metabolic vulnerabilities of CD8⁺ T cells and cancer cells, we developed a high-throughput <i>in vitro</i> pharmacologic screening platform and used it to measure the cell type-specific sensitivities of activated CD8⁺ T cells and B16 melanoma cells to a wide array of metabolic perturbations during antigen-specific killing of cancer cells by CD8⁺ T cells. We illustrated the applicability of this screening platform by showing that CD8⁺ T cells were more sensitive to ferroptosis induction by inhibitors of glutathione peroxidase 4 (GPX4) than B16 and MC38 cancer cells. Overexpression of ferroptosis suppressor protein 1 (FSP1) or cytosolic GPX4 yielded ferroptosis-resistant CD8⁺ T cells without compromising their function, while genetic deletion of the ferroptosis sensitivity-promoting enzyme acyl-CoA synthetase long-chain family member 4 (ACSL4) protected CD8⁺ T cells from ferroptosis but impaired antitumor CD8⁺ T-cell responses. Our screen also revealed high T cell-specific vulnerabilities for compounds targeting NAD⁺ metabolism or autophagy and endoplasmic reticulum (ER) stress pathways. We focused the current screening effort on metabolic agents. However, this <i>in vitro</i> screening platform may also be valuable for rapid testing of other types of compounds to identify regulators of antitumor CD8⁺ T-cell function and potential therapeutic targets.