Pathological Complete Response in a Patient With HER2-Negative Esophagogastric Junction Cancer Undergoing Conversion-Intent Surgery After Ramucirumab Plus Paclitaxel Following Nivolumab-Based Chemotherapy: A Case Report.

内容摘要

Nivolumab and other immune checkpoint inhibitors (ICIs) have improved survival in advanced gastric cancer. However, optimal management after progression on ICI-containing therapy remains uncertain. We report a case of HER2-negative esophagogastric junction (EGJ) cancer that showed a marked radiological and metabolic response to second-line ramucirumab plus paclitaxel (RAM + PTX) after nivolumab-based chemotherapy, allowing conversion-intent surgery, after which pathological complete response (pCR) was confirmed in the resected specimen. A 76-year-old woman was diagnosed with advanced HER2-negative EGJ adenocarcinoma with para-aortic lymph node metastases (cT3N3bM1[Lym], Stage IVB according to the 15th edition of the Japanese Classification of Gastric Carcinoma). The tumor was classified as Siewert type III with minimal esophageal invasion. First-line SOX plus nivolumab was administered, but disease progression with mediastinal lymph node enlargement and suspected pulmonary metastases was observed after five cycles. Second-line RAM + PTX was subsequently initiated and resulted in marked regression of the primary tumor and metastatic lesions on computed tomography and endoscopy, with metabolic complete response on positron emission tomography-computed tomography. Although chemotherapy was temporarily interrupted because of immune-related type 1 diabetes mellitus, metabolic complete response was maintained after glycemic control with insulin therapy. Following multidisciplinary evaluation of treatment response and resectability, robot-assisted proximal gastrectomy with D2 lymphadenectomy and double-flap reconstruction was performed. Histopathological examination demonstrated no residual viable tumor cells (ypT0N0), consistent with pCR. The postoperative course was uneventful, and the patient remains clinically recurrence-free 10 months after surgery. This case suggests that RAM + PTX after nivolumab-based chemotherapy may achieve substantial tumor regression in selected patients with advanced EGJ cancer and may provide an opportunity for conversion surgery. Robot-assisted proximal gastrectomy with double-flap reconstruction was feasible after successful systemic therapy. Careful multidisciplinary assessment and accumulation of further clinical evidence are needed to clarify the role of sequential systemic therapy and surgical intervention in this setting.