Sustained Clinical Response to Ivosidenib in Previously Treated Patients with Advanced Intrahepatic Cholangiocarcinoma Harboring an IDH1 R132 Mutation: Two Case Reports

Introduction: Patients with progressing intrahepatic cholangiocarcinoma (iCCA) harboring an isocitrate dehydrogenase 1 (IDH1) mutation who received ivosidenib showed a median progression-free survival (PFS) benefit of 1.3 months compared to placebo in the phase 3 ClarIDHy trial. Case Presentations: We describe 2 consecutive patients with previously treated unresectable and metastatic iCCA harboring an IDH1 R132 mutation who achieved durable clinical responses with ivosidenib 500 mg once daily for >12 months until disease progression. In one case with a mixed response, a single progressive liver metastasis was additionally treated locally with interstitial brachytherapy, while ivosidenib was continued until further progression. Ivosidenib therapy resulted in long-term disease control with PFS of 20 and 13 months and duration of treatment of 26 and 13 months, respectively, with no relevant side effects. Conclusion: Patients with unresectable or metastatic IDH1-mutated iCCA can achieve sustained clinical responses for >12 months with ivosidenib. No new safety signals were observed during long-term treatment with ivosidenib.