[A Case of Recurrent Gastric Cancer with Durable Complete Response after Short-Term Nivolumab Therapy]

We report the case of a patient with recurrent gastric cancer that showed a complete response(CR)after short-term nivolumab administration. A 76-year-old woman was diagnosed with unresectable advanced gastric cancer(T4b, N+, M0, cStage ⅣA). The patient was administered 7 courses of SOX. Since the primary lesion was reduced significantly after the chemotherapy, radical gastrectomy was performed. Although postoperative adjuvant chemotherapy with weekly nab-PTX was performed, cancer recurrence occurred in the abdominal cavity, and another surgery was performed. However, complete resection was difficult to achieve. Postoperatively, chemotherapy was continued; however, CEA levels increased, and thus RAM+PTX was administered as second-line treatment. Stable disease was maintained for a while; however, disease progression occurred eventually. Thus, RAM+PTX was discontinued after 8 courses, and nivolumab was administered as the third-line treatment. However, due to the rapid deterioration of renal function, nivolumab could not be continued after 3 courses. After nivolumab discontinuation, CEA levels normalized and the image showed CR. Approximately 1.5 years have passed since then, with no report of recurrence without any treatment. Although nivolumab has been shown to be useful as a third-line treatment for unresectable advanced/recurrent gastric cancer, there are few reports demonstrating CR and none showing maintenance of CR after short-term nivolumab administration. Moreover, the rationale of continuing nivolumab is unclear once clinical CR is achieved. Our experience shows the feasibility of discontinuation of short-term nivolumab if CR is achieved.