Engineered OVs have been tested in several Phase I-III clinical trials, and Talimogene laherparepvec (Imlygic®), an Herpes Simplex Virus (HSV) expressing the granulocyte macrophage colony stimulating factor (GM-CSF), has been recently approved by FDA and EMA for the treatment of melanoma. The gene discussed is CSF2; the disease is melanoma.