Abstract
A 65-year-old Japanese man presented with right-sided abdominal pain. Findings from computed tomography, esophagogastroduodenoscopy, and endoscopic ultrasound-guided tissue acquisition led to a diagnosis of ampullary cancer with para-aortic lymph node metastasis. To treat the biliary obstruction, a metallic stent was placed endoscopically. Combination therapy comprising gemcitabine-, cisplatin-, and durvalumab-induced marked regression of the lymph node metastases, and the patient's carbohydrate antigen 19-9 levels decreased to within normal limits. After eight gemcitabine, cisplatin, and durvalumab therapy cycles, the treatment was switched to maintenance durvalumab monotherapy. This monotherapy was continued for four cycles without adverse effects, and it maintained the metastatic lymph node's regression and the decreased carbohydrate antigen 19-9 levels. No stent occlusion was observed. Histopathological examination of the biopsy specimen obtained before treatment initiation revealed intestinal-type ampullary cancer, and programmed cell death ligand 1 expression was positive in 10% of tumor cells and 5% of immune cells. Despite the limited evidence regarding the long-term efficacy of gemcitabine, cisplatin, and durvalumab therapy in ampullary cancer, this case report demonstrates its sustained effectiveness over 18 months in a patient with intestinal-type ampullary cancer.