Immunotherapy has also made great progress in the therapy of CRC, two kinds of programmed cell death 1 (PD-1) blocking antibodies, pembrolizumab and nivolumab, show efficacy in patients with metastatic CRC who have defects in repair of mismatch repair and high microsatellite instability [5, 6]. Here, PDCD1 is linked to colorectal carcinoma.