This genetically modified herpes simplex virus encodes GM-CSF and, upon intratumoural injection, has demonstrated overall response benefit over subcutaneous GM-CSF in advanced melanoma patients.89 GM-CSF gene transfection into autologous or allogeneic tumour cells has been the basis for GVAX products which, in the allogeneic setting, have not met satisfactory endpoints in prostate cancer phase III trials, but hold promise in the autologous setting and in combination regimens in pancreatic cancer.90,91. Here, CSF2 is linked to melanoma.