PDCD1 and colorectal carcinoma: The success of Chekmate-649, ORIENT-16, Keynote-177, Keynote-590 clinical trials has made anti-PD-1/PD-L1 antibody combined with chemotherapy has become the primary first-line treatment for GC (GC), mismatch repair defect (dMMR)/high microsatellite instability (MSI-H) colorectal cancer (CRC) (19).