The liver gene delivery of high IL-15 makes CD8+ T cells and NK cells proliferate in large quantities, resulting in the accumulation of CD8+ T cells in the body (over 40 days), especially in the liver. Hyper-IL-15 therapy has significant therapeutic effects on established liver metastases and even autologous HCC induced by DEN. These effects can be depleted by CD8+ T cells instead of NK cells. This evidence concerns the gene IL15 and hepatocellular carcinoma.