PDCD1 and colorectal carcinoma: A fluoropyrimidine/oxaliplatin doublet had remained a first-line standard-of-care for all advanced stage colon cancers for decades, regardless of microsatellite status, until June 2020, when the PD-1 inhibitor pembrolizumab was granted approval by the US Food and Drug Administration (FDA) for the first-line treatment of patients with unresectable or metastatic MSI-H or dMMR CRC [116].