Following impressive results in IDH1-mutant acute myeloid leukaemia [41] and a dose-escalation and expansion study within CCA—which included no patients with pCCA [42]—the phase 3 ClarIDHy trial demonstrated improved mPFS for ivosidenib versus placebo (2.7 vs. 1.4 months; HR 0.37, 95% CI 0.25–0.54; p < 0.0001) in patients with previously treated, IDH1-mutated CCA, and was subsequently FDA-approved in this setting [21,43]. The gene discussed is IDH1; the disease is cholangiocarcinoma.