In dogs with cancer, the exploration of single agent IL-2 as an anti-tumor immune cytokine has been demonstrated by subcutaneous, intratumoral, inhalation (liposome), and intravenous (DNA plasmid) routes in several different tumor histologies such as OS, mast cell tumor, and peripheral nerve sheath tumors (108, 182–184). This evidence concerns the gene IL2 and neoplasm.