Fig. 2From: Circulating tumor cells in cancer patients: developments and clinical applications for immunotherapyThe four current immunotherapeutic strategies targeting circulating tumor cells. a Immune checkpoint therapy: The dual inhibition of both CD47 and PD-L1 inhibits immune evasion to promotes immune activation by T cells and NK cells. b Monoclonal antibody therapy: Depending on FcγRI and FcγRIV, monoclonal antibodies (mAbs) mediate CTC elimination by Kupffer cells. c “Unnatural killer cell” therapy: Leukocytes coated with E-selectin (ES)/tumor necrosis factor-related apoptosis inducing ligand (TRAIL) liposomes enhance the apoptotic effects of CTCs. d In vivo P-aPDL1 therapy: Conjugating anti-PDL1 (aPDL1) to the surface of platelets can facilitate the delivery of aPDL1 to target CTCsBack to article page