Several cytokines, including IFN-α, IFN-γ, IL-2, IL-12, IL-15, and granulocyte-macrophage colony-stimulating factor (GM-CSF), exhibit antitumor properties in preclinical models.7 These cytokines slow tumor growth either by directly inhibiting proliferation and promoting apoptosis, or indirectly by mobilizing an antitumor immune response. This evidence concerns the gene IL15 and neoplasm.