Olutasidenib (FT-2102) is a highly potent, orally bioavailable, brain-penetrant, and selective inhibitor of mutant IDH1. Olutasidenib was designed to reduce R-2-HG and revert pathologic epigenetic modifications that impair cellular differentiation to restore regulatory enzyme function. In patients with AML, susceptible IDH1 mutations are defined as those leading to increased levels of 2-hydroxyglutarate (2-HG) in the leukemia cells and where efficacy is predicted by 1) clinically meaningful remissions with the recommended dose of olutasidenib and/or 2) inhibition of mutant IDH1 enzymatic activity at concentrations of olutasidenib sustainable at the recommended dosage according to validated methods. The most common of such mutations in patients with AML are R132H and R132C substitutions. In vitro, olutasidenib inhibited mutated IDH1 R132H, R132L, R132S, R132G, and R132C proteins; wild-type IDH1 or mutated IDH2 proteins were not inhibited. Olutasidenib inhibition of mutant IDH1 led to decreased 2-HG levels in vitro and in in vivo xenograft models. On December 1, 2022, the FDA approved olutasidenib (brand name Rezlidhia) capsules for adult patients with relapsed or refractory acute myeloid leukemia with a susceptible IDH1 mutation as detected by an FDA-approved test.