Advanced Cholangiocarcinoma With High Tumor Mutation Burden Achieving Complete Response to Immune Check Point Inhibitor.

Background/aim: Genomic examination of tumor tissue has been clinically accepted, and the identification of actionable mutations for molecular-targeted therapy may provide substantial survival benefit for patients with advanced malignancies.

Case Report: A female patient in her 60s showed a stenosis of the afferent loop of the small intestine because of circumferential metastatic tumor 14 months after curative surgery for hilar cholangiocarcinoma. Chemotherapy with gemcitabine plus cisplatin was administered for 18 months. An oncopanel examination was performed during chemotherapy, and a high tumor mutation burden was revealed. At 38 months after surgery, a new recurrent tumor, 2.7 cm in size, was observed in the abdominal wall, which was histologically proven to be metastatic adenocarcinoma. Atezolizumab was administered. After three cycles of treatment, treatment was switched to pembrolizumab because of its acceptance by healthcare insurance. The recurrent tumors in the abdominal wall and small intestine disappeared 6 months after the administration of immune checkpoint inhibitor, and the patient has continued pembrolizumab, surviving for 76 months after surgery without any clinical evidence of tumor.

Conclusion: Immune checkpoint blockade successfully prolonged the survival of a patient with advanced hilar cholangiocarcinoma with high tumor mutation burden, although the optimal number of mutations for such a successful response needs to be clarified.