The expression levels of immune suppression-associated genes such as Foxp3, indoleamine-2,3-dioxygenase (IDO1), interleukin-10 (IL-10), and transforming growth factor-β (TGF-β) in the HMGB1-knockout tumor tissues were almost equivalent or slightly increased compared to the corresponding levels in the WT tumor tissues. This evidence concerns the gene IDO2 and neoplasm.