Since late 2016, PD-1 inhibitors have been approved for melanoma, non-small cell lung cancer, renal cell carcinoma, and head and neck cancer by the U.S. Food and Drug Administration; compared with old cytotoxic agents, PD-1 inhibitors have superior efficacy with an improved safety profile in various tumour types6. This evidence concerns the gene PDCD1 and non-small cell lung carcinoma.