PD-1 is a common immunosuppressive factor on the surface of T cells, and PD-L1 is overexpressed on the surface of malignant tumour cells, whereas the interaction between PD-1 and PD-L1 leads to therapeutic failure by inhibiting the activity of effector T cells and enhancing the function of immunosuppressive Tregs and ultimately inducing immune escape [55]. The gene discussed is CD274; the disease is neoplasm.