Guidelines from the National Comprehensive Cancer Network (NCCN) and the European Society for Medical Oncology (ESMO) recommend that PD-L1 be used as a primary determinant for immunotherapy selection in metastatic NSCLC: patients with high PD-L1 expression (TPS ≥ 50%) are eligible for anti-PD-1/PD-L1 monotherapy, while those with intermediate expression (TPS 1–49%) are advised to receive combination chemo-immunotherapy [199]. The gene discussed is PDCD1; the disease is non-small cell lung carcinoma.