PDCD1 and neoplasm: Although anti-programmed cell death 1 (PD1)/programmed cell death ligand 1 (PD-L1) immunotherapy has emerged as a standard of care for stage III-IV NSCLC patients, it cannot be ignored that there are still part patients who do not respond to immunotherapy, which may be due to complex tumor heterogeneity or some molecular mechanisms that have not yet been elucidated [10, 11].