CSF2 and neoplasm: T-VEC is genetically created through deletion of ICP34.5 and ICP47 and insertion of GM-CSF.36 The deletion of ICP34.5, encoding the neurovirulence factor, stops virus replication in neurons but supports virus replication in tumor cells.37 Furthermore, in the placement of ICP34.5 T-VEC contains two copies of GM-CSF, which promotes dendritic cell maturation.