Finally, limitations of our study should be mentioned: (1) cell lines were used as a model system expressing putative NSCLC -related antigens, (2) second- or multiple-line application of PD-1 blockade therapy, (3) cross-sectional study without longitudinal follow-up of the soluble mediators or cell surface markers, (4) relatively small number of subjects in the study cohorts, and (5) the complex immunophenotyping of smoker but non-tumorous cases would be relevant, but in those cases, the appearance and disappearance of previous tumors could not be ruled out. This evidence concerns the gene PDCD1 and non-small cell lung carcinoma.