In the course of treatment, it was found that targeting PD-1 led to the expansion and recruitment of anti-tumor T cells, while anti-CTLA4 therapy would produce new T cell clones, indicating that CTLA4 and PD-1 might simultaneously target the synergistic anti-tumor effect, and the anti-tumor effect of their combination therapy was better than that of single therapy [109]. This evidence concerns the gene PDCD1 and neoplasm.