PDCD1 and colorectal carcinoma: In the treatment of CRC, the PD-1 inhibitors pembrolizumab and nivolumab, which have been approved by the Food and Drug Administration (FDA), led a to durable response in patients with metastatic CRC that is mismatch-repair-deficient (dMMR) and microsatellite instability-high (MSI-H) (dMMR-MSI-H).