IDH1 mutations are less frequent in AML compared to IDH2; however, the more durable responses to oral inhibitor AG-120, now called ivosidenib, led to its FDA approval initially for R/R AML with IDH1 mutations in July 2018, soon followed by approval for newly diagnosed AML patients who were unable to obtain intensive chemotherapy by May 2019. The gene discussed is IDH2; the disease is acute myeloid leukemia.