This approach raises several questions, in particular whether PD-1/PD-L1 expression status is important in order to select patients eligible for these treatments, which technique is best suited in evaluating their levels, if these tumor immunity factors may be regulated by miRNAs, and how to define a threshold for positive PD-1/PD-L1 staining of tissue samples, considering that certain patients respond to treatment targeting PD-L1/PD-1, despite low or absent immunoreactivity for these biomarkers. The gene discussed is PDCD1; the disease is neoplasm.