Immune checkpoint inhibitors (ICIs), including anti-programmed cell death-1 (PD-1)/programmed death-ligand 1 (PD-L1) drugs (such as nivolumab, pembrolizumab, and atezolizumab) and anti-cytotoxic T-lymphocyte antigen-4 (CTLA-4) agents (ipilimumab), have become key treatments for patients with advanced or recurrent non-small-cell lung cancer (NSCLC) [25]. The gene discussed is PDCD1; the disease is non-small cell lung carcinoma.