Long‑term treatment with ivosidenib in IDH1‑mutant combined hepatocellular–cholangiocarcinoma: a case report

Combined hepatocellular–cholangiocarcinoma (cHCC-CCA) is a rare liver cancer characterized by cancerous cells of bile duct origin. Treatment options are limited and prognosis is poor. When a mutation of isocitrate dehydrogenase-1 ( IDH1 ) is present, the patient may be eligible for treatment with ivosidenib, an IDH1 inhibitor. Ivosidenib improved overall survival versus placebo in patients with previously treated advanced CCA with IDH1 mutation in the ClarIDHy phase III trial. We describe the case of a male patient aged 55 years diagnosed with cHCC-CCA with an IDH1 pathogenic mutation who failed first-line treatment with cisplatin plus gemcitabine. Ivosidenib 500 mg once daily treatment was initiated, and after 3 months, partial regression of the target lesion was observed, and after 22 months, best overall response was partial remission. No adverse events were reported. After 35 months, the patient continued to receive ivosidenib since the target lesion had not progressed, and treatment was very well tolerated. Ivosidenib appeared to be an effective and well-tolerated treatment for this patient with previously treated cHCC-CCA who had IDH1 mutations.