However, the application of immune checkpoint inhibitors (ICIs), especially PD-1/PD-L1 inhibitors, in advanced LC, along with evidence of the imbalance of immune checkpoint protein (PD-1 and PD-L1) expression and changes in the immune microenvironment in COPD patients (8, 11, 12), revealed that COPD-related LC may respond better to immunotherapy (8, 13). Here, PDCD1 is linked to chronic obstructive pulmonary disease.