Both preclinical and clinical trials established that the secretion of interferon (IFN)-γ by tumor-specific CD8+ T cells contribute to the upregulation of PD-L1 and, seemingly, PD-L2 on tumor cells [19,20,21] that ligate PD-1 on activated T cells, further inhibiting T-cell effector function [10]. Here, PDCD1 is linked to neoplasm.