Extensive tumor inflammation shows hyperactivation of interferon‐γ (IFN‐γ) signaling, leading to elevated indoleamine 2, 3‐dioxygenase 1 (IDO1) expression.[8] High IDO1 level causes tryptophan (Trp) consumption via the kynurenine (Kyn) pathway. This evidence concerns the gene IDO1 and neoplasm.