Li [100] and Silvestre [101] demonstrated that the fourth- generation CD19-targeted CAR (CAR.19) co-expressing IL-15 or IL-15/IL-15Rα significantly enhanced NK-92 cell proliferation, proinflammatory cytokine secretion, and cytotoxic activity against cancer cell lines in vitro and in a xenograft mouse model. The gene discussed is IL15; the disease is cancer.