POLD1 Mutations May be Effective Predictive Biomarker for the Response to Durvalumab plus Gemcitabine and Cisplatin in Metastatic Cholangiocarcinoma: A Case Report

Abstract Biliary tract cancers have a poor prognosis with limited treatment options. While immune checkpoint inhibitors have recently shown modest survival benefits as standard first-line therapy, reliable predictive biomarkers for the response to treatment remain lacking. This case report describes a 61-year-old female diagnosed with metastatic intrahepatic cholangiocarcinoma who was treated with durvalumab plus cisplatin and gemcitabine. Next-generation sequencing showed the presence of the POLD1 R689W mutation, microsatellite stability, and low tumor mutational burden. The best response was complete response, and progression-free survival was 13.8 months. A comprehensive review of bioinformatic databases showed that POLD1 mutations have rarely been identified in cholangiocarcinoma. Functional studies of this mutation in cholangiocarcinoma are warranted.