Figure 1.

T cell metabolism and the tumour microenvironment. T cells face various metabolic challenges within the TME. Direct competition for nutrients arises such as glucose, glutamine, and amino acids, with the tumour outcompeting T cells. The tumour can also produce immunosuppressive nutrients such as lactate and kynurenine, and intrinsically modulate T cell metabolism through PD-1 checkpoint ligation and the production of TGF-β. This metabolic modulation of T cells within the TME results in an impaired anti-tumoural response. IDO, indoleamine 2,3-dioxygenase; OXPHOS, oxidative phosphorylation; PD-1, programmed cell death-1; PD-L1, programmed cell death-ligand 1; TCA cycle, tricarboxylic acid cycle; TGF-β, transforming growth factor-beta; and TME, tumour microenvironment.