Despite the great success of immune checkpoint therapies blocking the PD-1/PD-L1 interaction in a small subset of various cancer patients [12,13,14,15,16,17,18,19,20], the treatment failed in most cases, including in CRC patients, due to intrinsic unresponsiveness and/or acquired resistance [21,22,23,24,25,26]. The gene discussed is PDCD1; the disease is colorectal carcinoma.