PDCD1 and neoplasm: As the malignant process can lead to generalized immune dysfunction and disease progression [4–6], there has been success across multiple tumor types with the introduction of various immunotherapies into systemic circulation including monoclonal antibody checkpoint blockers like those against programmed death-ligand 1 (PD-L1) and its receptor, programmed cell death protein 1 (PD-1) [7].