PDCD1 and cancer: Many advances in antitumor therapies have been achieved with antagonistic antibodies targeting the programmed cell death protein 1 (PD-1) or its ligand (PD-L1); however, many cancer patients still develop resistance to anti–PD-1/PD-L1 treatments often associated with the upregulation of other immune checkpoints such as Lymphocyte Activation Gene-3 (LAG-3).