When administrated as first-line therapy, pembrolizumab provided significantly prolonged PFS and OS over chemotherapy for metastatic NSCLC with PD-L1 TPS ≥ 50%.20, 21 Similarly, in the KEYNOTE-042 trial, patients with PD-L1 TPS ≥ 1%, the superiority of pembrolizumab over platinum-based chemotherapy is confirmed in treatment-naive metastatic NSCLC without epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK) driver mutations.22 Here, ALK is linked to non-small cell lung carcinoma.