Altogether, an extensive understanding of the mechanisms by which PD-L1 is governed will help us to reach a comprehensive evaluation of PD-1/PD-L1 targeting therapy, and further potentiate the efficacy and expand the usage of this kind of cancer therapy via patient selection and rational combination with other antineoplastic agents, as well as develop new effective strategies for cancer immunotherapy. The gene discussed is PDCD1; the disease is cancer.