Pre-activation of NK cells with IL-18, IL-12, and IL-15 prior to adoptive NK cell transfer leads to high levels of IFN-γ production coupled with enhanced NK cell survival [42], while co-administration of IL-15 has been shown to amplify the anti-tumor activity of IL-12 in a murine metastatic melanoma model [16,43]. This evidence concerns the gene IL15 and metastatic melanoma.