Of interest, IDH1/2 mutated cancers accumulate 2-hydroxyglutarate in tumour tissue and release the molecule in blood, and the measurement of 2-hydroxyglutarate might be used as both a surrogate biomarker for IDH1/2 mutational status and a non-invasive test for the assessment of tumour burden in ICC [47]. This evidence concerns the gene IDH1 and intrahepatic cholangiocarcinoma.