Moreover, CAR-T cells secreting IL-7 [97], IL-12 [98–101], IL-15 [102–107], IL-18 [108–110], IL-33 [111], and IL-36γ [112] have also exhibited improved persistence or anti-tumor ability in preclinical or clinical trials; however, the continuous expression of pro-inflammatory cytokines such as IL-12 may lead to systemic toxicity [113, 114]. The gene discussed is IL15; the disease is neoplasm.