For molecular targeted therapy as second-line therapy, only ivosidenib (a small-molecule targeted inhibitor of IDH1) significantly improved median PFS compared with placebo (2.7 months vs 1.4 months, hazard ratio 0.37, one-sided p<0.0001) in patients with previously treated IDH1-mutant cholangiocarcinoma 21. Here, IDH1 is linked to cholangiocarcinoma.