CD8A and cancer: analyzed the TME of biliary tract cancers patients samples using IMC and found that PD-1+CD8+ T cells, known to be important for the response to anti-PD-1 therapy, were not only higher in early-stage than in late-stage cancers, but they were also more numerous in direct interaction with tumor cells whereas CD8+ T cells in the stroma, at distance of tumor cells, were mainly PD-1- (44).