CCL21 and neoplasm: Improving tumor trafficking could be achieved in two main ways: (1) CAR T-cells with chemokine receptors secreted by PCa such as CCL2, CCL21, (2) by converting the “cold” anti-immunogenic PCa into “hot” immunogenic tumor cells, thereby engaging the intrinsic ability of PCa by employing chemotherapy or local radiotherapy alongside with CAR T-cell therapy [93,94,95,96].