Ivosidenib (AG-120) is an inhibitor of isocitrate dehydrogenase 1 (IDH1) This experimental drug inhibits mutant IDH1, leading to increased differentiation and decreased proliferation in IDH1 positive tumors and thus is thought to be promising for the treatment of IDH1-mutated tumors. In vivo treatment with AG-120 of TF-1 cells, primary human AML patient samples expressing mutant IDH1 and primary human blast cells cultured ex vivo showed that AG-120 is effective at lowering 2-HG levels and restoring cellular differentiation. It showed promising results in a phase I trial in patients with relapsed or refractory acute myeloid leukemia and is being evaluated in Phase III in previously-treated subjects with nonresectable or metastatic cholangiocarcinoma with an IDH1 mutation.