A potent, selective inhibitor of mutant IDH2 (IC50 = 23 nM) that inhibits 2-HG formation in human glioblastoma U87 and TF-1 cells expressing IDH2-R140Q (IC50s = 11 and 18 nM, respectively); suppresses cell growth of primary human AML cells and induces differentiation of immature blast cells towards macrophage and granulocytic lineages.