Similar studies have also found that IDH-mutated gliomas produce R-2-HG to promote tryptophan metabolism in infiltrating macrophages, thus leading to the activation of the aryl hydrocarbon receptor (AHR) signaling pathways in the macrophages and the inhibition of T cell function via immunosuppressive factors such as IL-10 [65]. This evidence concerns the gene IDH1 and central nervous system cancer.