CTLA4 and cancer: Recent studies have indicated that using anti‐PD‐1 antibodies in conjunction with other cancer treatment agents, like anti‐CTLA‐4 antibodies, exhibits initial therapeutic activity in metastatic colorectal cancer (mCRC) patients harboring mismatch repair deficiency (dMMR) or microsatellite instability‐high (MSI‐H) phenotypes, compared to monotherapy.