Therefore, based on the aforementioned molecular regulatory mechanisms of the PD-1/PD-L1 signaling pathway, it is not difficult to see that pathogen-infected cells utilize the PD-1/PD-L1 axis to promote the occurrence of immune inflammation in the local tumor microenvironment, breaking the immune balance of the organism and evading the attack of the host immune system. Here, PDCD1 is linked to neoplasm.