By targeting and blocking specific proteins on immune cells or cancer cells, ICIs overcome the mechanisms that cancer cells use to evade immune detection, reactivating the immune system to destroy cancer.[1, 2, 3] Notable examples of ICIs include agents that target PD‐1, PD‐L1, and CTLA‐4.[4, 5, 6] These therapies have shown remarkable success in treating a range of cancers,[7, 8, 9, 10] offering new hope to patients with previously limited treatment options. Here, CTLA4 is linked to cancer.