Teng et al. proposed a model that classified the tumor microenvironment into four distinct categories based on the PD-L1 expression and density of the TILs: type I (PD-L1+TILs+), type II (PD-L1−TILs−), type III (PD-L1+TILs−) and type IV (PD-L1−TILs+). The gene discussed is CD274; the disease is neoplasm.