[A Case of Recurrent Esophagogastric Junction Cancer with Long‒Term Complete Response by Trastuzumab Deruxtecan]

A 44-year-old man presented in December 2019 with a chief complaint of pericardial discomfort. Type 2 lesion at the esophagogastric junction and enlarged periaortic lymph nodes were observed. After neoadjuvant chemotherapy (docetaxel +oxaliplatin + S-1: DOS), he underwent proximal gastrectomy, double tract reconstruction and para-aortic lymph node dissection. The pathological examination showed residual para-aortic lymph node metastases, Ae, T3N1M1 (LYM) CY0P0H0, pStage Ⅳ, HER2 positive. In November 2021, the patient presented with para-aortic lymph node recurrence and was treated with S-1 + oxaliplatin (SOX) + trastuzumab (Tmab) and paclitaxel + ramucirumab, but the lymph nodes were enlarged and trastuzumab deruxtecan (T-DXd) therapy was started. After 4 courses, tumour markers normalised and para-aortic lymph nodes disappeared. After 17 courses, chemotherapy was discontinued after 1 year of complete response (CR). Sixteen months after completing chemotherapy, the patient maintained a CR. T-DXd was approved for the treatment of HER2-positive unresectable advanced or recurrent gastric cancer from the 6th edition of Gastric Cancer Treatment Guidelines. We report a case of long-term CR maintenance after T-DXd therapy for recurrent esophagogastric junction gastric cancer.