CSF2 and neoplasm: In T-VEC, the HSV-1 has been genetically modified such that within the virus, the neurovirulence factors related to the ICP34.5 loci have been removed and coding for expression of granulocyte macrophage colony-stimulating factor (GM-CSF) has been included, resulting in selective replication within tumor cells, lysis, and local induction of a tumor-specific immune response [17].