Some possible reasons for this are that 1) PD-L1 expression based on IHC were assessed by different anti-PD-L1 antibodies and staining methods (manual versus automated); 2) Different cut-off values to define PD-L1 positivity were applied, 1%, 5% and 10% were most used; and 3) PD-L1 expression is a dynamic process during cancer immune editing process [40]. The gene discussed is CD274; the disease is cancer.