PDCD1 and neoplasm: At present, PD-1/PD-L1 inhibitors are combined with chemotherapy, radiotherapy, targeted drug therapy and other immunotherapies, which increases the number of CD8+ T cells in the tumor microenvironment of patients, destroys the immune escape of tumors, and enhances the anti-tumor effect of PD-1/PD-L1 inhibitors (18–20).