Studies have reported that due to CH2/CH3 instability of Fc domain, IgG4 antibody is prone to aggregating with either IgG4 or IgG1 via Fc-Fc interaction (13, 14); moreover, anti-PD1 antibody might facilitate immune evasion of tumor cells in vivo by attenuating tumor-specific antibody mediated tumor killing (15–17). This evidence concerns the gene PDCD1 and neoplasm.