In agreement with our previous work (Tardito et al, 2015), isotopically labeled glutamine intravenously injected in glioma xenografts was neither efficiently taken up by the brain nor by tumors independent of their IDH status (Fig EV3A); thus, it can be ruled out that blood‐borne glutamine is a relevant source of carbons for D2HG production in IDHm glioma. The gene discussed is IDH2; the disease is central nervous system cancer.