CSF2 and metastatic melanoma: In October 2015, the first United States Food and Drug Administration-approved OV agent, talimogene laherparepvec (T-VEC), led the way for clinically effective virotherapy treatment of patients with metastatic melanoma.4,5 This genetically modified herpes simplex virus, encoding a human granulocyte macrophage colony-stimulating factor (GM-CSF) gene, is a lytic virus that promotes the release and presentation of tumor antigens to enhance an antitumor immune response both at the site of injection and systemically.6