CSF2 and cancer: ,3 Pexa-Vec, a thymidine kinase (TK)-deleted VV that encodes granulocyte-macrophage colony-stimulating factor (GM-CSF), has been shown to be safe and effective in a range of cancers, including melanoma,4,5 liver cancer,6, 7, 8, 9, 10, 11 and colorectal cancer9,12