In adult AML, dexamethasone has long been used to prevent or treat a severe inflammatory condition known as differentiation syndrome in patients with acute promyelocytic leukemia (APL) treated with all trans-retinoic acid (ATRA) and/or arsenic trioxide, or more recently in AML patients treated with IDH or FLT3 inhibitors (63, 64). The gene discussed is IDH1; the disease is acute promyelocytic leukemia.