IDH1 and cholangiocarcinoma: A retrospective analysis from the aforementioned ClarIDHy trial—which evaluated the efficacy of IDH1 inhibitor ivosidenib in mutant IDH1 CCA—showed that IDH1 mutation clearance as evaluated on plasma ctDNA in patients followed longitudinally correlated with disease control [35]; data from the same cohort also confirmed the feasibility of IDH1 mutation detection in plasma, with a blood-tissue concordance of 92%.