This is particularly relevant for patients with low frequency of pre-existing intra-tumoral CD8+ cells, who respond poorly to cancer immunotherapy (50) and particularly for the vast majority of human (CEA-expressing) colorectal cancer tumors with proficient mismatch repair (MMR) or with microsatellite stable (MSS) tumors who do not benefit from immunotherapy. This evidence concerns the gene CEACAM5 and cancer.