Encouragingly, in microsatellite stability (MSS) CRC patients, ARID1A mutation is defined as an immunologically active subgroup with abundant intra-tumoral T-cell infiltration, and these patients have the potential to benefit from immunotherapy, such as programmed death-1 monoclonal antibody (PD-1 mAb) [7, 12, 13]. The gene discussed is ARID1A; the disease is colorectal carcinoma.