Although the anti-tumor capacity of OVs including “Armed” OVs has been investigated for decades, OVs are only now being used clinically after the recent approval of talimogene laherparepvec (T-VEC), a herpes simplex-1 (HSV) oncolytic virus expressing granulocyte macrophage colony-stimulating factor (GM-CSF), for the treatment of malignant melanoma (8). This evidence concerns the gene CSF2 and melanoma.