CD274 and neoplasm: A phase 2 study by Le et al. revealed that the dMMR subset of CRC is sensitive to the PD-1 blockade immunotherapy, and the underlying mechanism is mainly ascribed to microsatellite instability (MSI) [24, 25], which is associated with high tumor mutation burden, inflammatory microenvironment, and PD-L1 upregulation, the features generally sparse in pMMR CRC tumors.