Understanding the mechanisms that control PD-1/PD-L1 expression in various types of cancer cells and the key involved accessory cells may not only identify important predictive biomarkers for controlling the efficacy of anti-PD-1/PD-L1 antibody-based immunotherapy but also help in the development of novel targeted therapies that can be combined with checkpoint inhibitors for additional clinical efficacy. The gene discussed is CD274; the disease is cancer.