PDCD1 and neoplasm: Pembrolizumab is the only anti-PD-1/PD-L1 inhibitor authorized in first line monotherapy for advanced non-squamous NSCLC without driver gene mutations (EGFR mutation and ALK fusion were excluded) expressing PD-L1 ≥ 50% of tumor cells and in second line monotherapy for advanced non-squamous or squamous NSCLC expressing PD-L1 ≥ 1%.