CD274 and cancer: Programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) are the current focus of immunotherapy and they play an important role in T lymphocyte-mediated cellular immunity.[9–11] In addition, some studies have shown that PD-1/PD-L1 was abnormally expressed in renal cell carcinoma, lung cancer, bladder cancer and other malignant tumors, and may be involved in the induction of maternal immune tolerance and the maintenance of pregnancy.[12]