PDCD1 and neoplasm: Other strategies were found to increase trafficking, such as disrupting the “sugar coat” by designing molecules that can break the sugar shield that tumors use to resist CAR -T cell attack (273), the combination of immune therapy with oncolytic viruses with effective tumor debulking by destroying the molecular shield used by some solid tumors to escape the immune system attack (274, 275), and using nanobody-based CAR-T cells such as PD-1/CTLA-4- antibodies secreting CAR-T cells (276).