IDH1 and cholangiocarcinoma: Subsequent studies revealed that mutations in IDH1 or IDH2 are prevalent in a variety of cancer types, including low‐grade glioma and secondary glioblastoma (~80%),7, 8 acute myeloid leukemia (AML, ~20%),9, 10 and intrahepatic cholangiocarcinoma (~10%).11, 12