CD274 and neoplasm: Moreover, Teng and colleagues proposed that four different types of tumor microenvironment exist based on the presence or absence of TILs and PD‐L1 expression levels (type I: TILs+ and PD‐L1+; type II: TILs− and PD‐L1−; type III: TILs+ and PD‐L1−; type IV: TILs− and PD‐L1+) 12.