IDH2 and cholangiocarcinoma: In recent years, IDH inhibitors targeting IDH mutants, including ivosidenib and enasidenib (Table 1), have been approved by the Food and Drug Administration to be used in patients with IDH1 or IDH2 mutant recurrent or refractory AML, respectively (Kim, 2017; Dhillon, 2018), while trials of IDH inhibitors for other tumors such as cholangiocarcinoma, chondrosarcoma, and myelodysplastic syndrome are still underway (Abou-Alfa et al., 2020; Stein et al., 2020; Tap et al., 2020).