PLK1 and cancer: So far, several CCC-targeting strategies for cancer treatment have been proposed; 1) inhibition of cancer cell intravasation using EpB2, PLK1 inhibitor, and anti-integrin antibody, 2) dissociation of CCC clusters or prevention of their formation using HPSE inhibitors, Na+/K+-ATPase inhibitors, platelet receptor inhibitors, and urokinase, 3) interference with metabolism, homeostasis, and immune cell-mediated survival, 4) immune checkpoint inhibition using anti-CD47, anti-PDL1/PD1, and anti-CTLA4 antibodies, 5) use of engineered CCCs as therapeutic vehicles, and 6) CCC-based chronotherapy [46].