Four types of TIL and PD-L1 expression status have been proposed to predict tumour responses to immune checkpoint inhibitors: type I (PD-L1+/TIL+; adaptive immune resistance), type II (PD-L1-/TIL-; immunological ignorance), type III (PD-L1+/ TIL-; intrinsic induction) and type IV (PD-L1-/TIL+; tolerance) (Teng et al., 2015). This evidence concerns the gene CD274 and neoplasm.