The tumors treated with ttIL-12 showed dramatically higher levels of IFNγ than those treated with Ctrl (P < 0.05), higher frequency of CD8+ T cells (P = 0.0358), and lower frequencies of MDSCs (P = 0.0458) and Tregs (P = 0.0059) (Additional file 1: Figure S8), suggesting that ttIL-12 treatment converted the immune profile in these osteosarcoma PDX tumors to the IFNγHiCD8HiFOXP3LowCD33Low immune profile associated with longer OS. This evidence concerns the gene IFNG and osteosarcoma.