2017), IL-18 (Loeffler et al. 2009), IL-2 (Kubiak et al. 2021; Barbé et al. 2005; Gniadek et al. 2020), and GM-CSF (Gurbatri et al. 2020). Of these, an IL-2 expressing strain of Salmonella has progressed the furthest. Promising pre-clinical efficacy in a canine model of osteosarcoma (Fritz et al. 2016) led to a Phase I single-dose clinical trial in human patients with metastatic gastrointestinal tumors (Gniadek et al. 2020). This evidence concerns the gene IL2 and osteosarcoma.