PDCD1 and neoplasm: Blockade of immune checkpoints such as PD-1 and its ligand PD-L1 has achieved unprecedented success across malignancies, particularly in the combination setting, including in melanoma, renal cell, high microsatellite instable (MSI-H) colorectal, triple-negative breast cancer (TNBC) and bladder cancers, and NSCLC, where tumor PD-L1 expression is observed in 14% to 100% of patients [10].