A potent, selective inhibitor of mutant IDH1 (isocitrate dehydrogenase 1). AGI-5198 inhibits IDH1 R132H and R132C mutants in vitro with IC₅₀ values of 0.07 and 0.16 µM, respectively, but not wild-type IDH1, wild-type IDH2, or IDH2 mutants (IC₅₀ s > 100 μM). Under conditions of near complete 2-HG (2-hydroxyglutarate) inhibition, AGI-5198 can induce demethylation of histone H3K9me3 and expression