In a randomized phase III trial of intratumoral T-VEC versus GM-CSF injection in unresectable stage III/IV melanoma (OPTiM trial), 19.3% (n = 57) of patients treated with T-VEC had a durable response lasting ≥ 6 months compared to 1.4% (n = 2) in the GM-CSF cohort [6]. This evidence concerns the gene CSF2 and melanoma.