In addition to the programmed cell death protein 1 (PD-1) and its ligand (PD-L1), vascular endothelial growth factor (VEGR), and vascular endothelial growth factor receptor (VEGFR), the most commonly used cancer therapies target proteasomes, epidermal growth factor receptor (EGFR), human epidermal growth factor receptor-2 (HER2), HER2 dimer, v-Raf murine sarcoma virus oncogene homolog B (BRAF), anaplastic lymphoma kinase (ALK), mammalian targets of receptor activators (RANKL) and rapamycin (mTOR) of nuclear factor κβ ligands (7, 81). Here, PDCD1 is linked to cancer.