In canine patients, IL-2 delivered subcutaneously, intralesionally, by inhalation and via liposome-DNA complexes encoding IL-2 gene, as a monotherapy or in combination with other modalities, promoted regression in dogs with oral melanoma, soft tissue sarcoma, squamous cell carcinoma and pulmonary metastases from osteosarcoma (126–131). Here, IL2 is linked to osteosarcoma.