IDO1 and neoplasm: Adding to that, CD8A expression correlated significantly with CD274, PDCD1, PDCD1LG2, IDO1, LAG3, ILT2, HAVCR2, TIGIT, ADORA2A and ILT4 expression in the tumor compared to unexposed normal skin, reiterating that CD8 expression is of paramount significance for a successful response to ICI therapies (57, 58) (Figure S7B).