CSF2 and neoplasm: This oncolytic HSV-1 backbone has demonstrated improved tumour shrinkage properties compared to previously developed oncolytic viruses and has been used to successfully express a range of therapeutic genes in pre-clinical testing, including granulocyte macrophage colony-stimulating factor (GM-CSF), retroviral glycoprotein, pro-drug activating system, and Tumor Necrosis Factor-Alpha (TNFα) [28-30].