Currently, immunotherapy has made significant breakthrough, especially programmed death 1/programmed death-ligand 1 (PD-1/PD-L1) checkpoint inhibitors (e.g, Nivolumab, Pembrolizumab, Atezolizumab, Durvalumab and Avelumab, etc.)have brought clinical benefits to patients with various pathological types of lung cancer, including squamous cell carcinoma, adenocarcinoma and small cell lung cancer. This evidence concerns the gene CD274 and small cell lung carcinoma.