PDCD1 and neoplasm: For the increase of Treg cells in the antibody monotherapy, it is possible that the PD-1 expressed Treg cells were protected by anti-PD-1 antibody via blocking the interaction between PD-1 and PD-L1 in tumor tissues 52; but for the inhibitory effect on the Treg cells by CGA that we have seen in the combination group, more investigation is needed.