TIGIT and neoplasm: Given that PD-1 and TIGIT inhibition significantly altered metabolism in OAC cells and that inhibition of oxidative phosphorylation or glycolysis significantly altered PD-1 and TIGIT expression on the surface of a subpopulation of OAC cells, this further highlights a role for PD-1 and TIGIT tumour cell intrinsic signalling in regulating OAC cell metabolism and may potentially suggest the existence of a positive/negative feedback loop between the expression of these ICs and regulation of metabolism in OAC cells.