CD8A and colorectal carcinoma: Several features of genomic instability, such as microsatellite instability (MSI), chromosomal instability and CpG island methylator phenotype, have emerged as major predictive markers for the efficacy of ICB.37,38 CRC patients with MSI-high tumors tend to have a good response to anti-PD-1 therapy, with enriched CD8+ T cells and activated dendritic cells as well as a higher expression of neoantigens in MSI-high tumors than in MSI-low tumors.37,39,40 These findings indicate that immune cell infiltration in tumors is a critical determinant for the clinical response to ICB.