The PD-1-TREM2 scFv not only inhibits the PD-1/PD-L1 signaling axis but also blocks the binding of ligands to the TREM2 receptor on MDSCs and TAMs, thereby reducing the ratio of MDSCs to TAMs, significantly enhances the effector function of CAR-T cells, and improves therapeutic efficacy in colorectal cancer. This evidence concerns the gene PDCD1 and colorectal cancer.