As it was the case for soft tissue sarcomas [34], 6 osteosarcoma bearing patients were subjected to a treatment combining (i) the local antiproliferative effects of cIFN-β and HSV-tk suicide gene therapy with (ii) the systemic effects triggered by osteosarcoma antigens in an immunostimulatory environment created by the slow secretion of hGM-CSF and hIL-2 [37]. Here, TKT is linked to osteosarcoma.