Recombinant OVs engineered with a GM-CSF gene are currently the most advanced tools in clinical development to enhance innate immune responses, which have been recently approved by the USA Food and Drug Administration for the treatment of metastatic melanoma.39 Despite many signs of progress, the appropriate immunomodulatory targets for intratumoral OV-based therapy are still unknown. Here, CSF2 is linked to metastatic melanoma.