For example, Sillajen’s Pexa-Vec (formerly known as Jennerex’s JX-594) is an oncolytic vaccinia virus encoding the granulocyte-macrophage colony-stimulating factor (GM-CSF) and has demonstrated promising results as a single agent in both Phase I and II clinical trials for the treatment of hepatocellular carcinoma [84,85]. The gene discussed is CSF2; the disease is hepatocellular carcinoma.