An orally available inhibitor of isocitrate dehydrogenase type 1 (IDH1), with potential antineoplastic activity. Upon administration, AG-120 specifically inhibits a mutated form of IDH1 in the cytoplasm, which inhibits the formation of the oncometabolite, 2-hydroxyglutarate (2HG). This may lead to both an induction of cellular differentiation and an inhibition of cellular proliferation in IDH1-expressing tumor cells. IDH1, an enzyme in the citric acid cycle, is mutated in a variety of cancers; it initiates and drives cancer growth by both blocking cell differentiation and catalyzing the formation of 2HG.