IL2 and neoplasm: The studies on PD-1 KO/KD found an increased CAR T cell infiltration into tumor tissue [100, 108], augmented survival and expansion of CAR T cells in the tissue [100, 105, 111, 118, 142], enhanced cytokine production against the tumors (such as IL-2) [100, 108, 111], better CAR T cell cytotoxicity [49, 53, 99, 100, 108, 111, 118, 119, 127, 139, 144, 176], and increased mice survival [31, 64, 99, 100, 104, 108, 109, 116, 117, 119, 139, 142] with PD-1 KO/KD mice compared to the controls.