CASE REPORT article
Front. Immunol.
Sec. Cancer Immunity and Immunotherapy
This article is part of the Research TopicPrecision Medicine and Targeted Therapies in Gastrointestinal and Genitourinary Solid TumorsView all 29 articles
Pathological Complete Response in Microsatellite-Stable Gastric Cancer with Liver and Bulky Lymph Node Metastases After Nivolumab-Based Chemotherapy and Surgery: A Case Report
Provisionally accepted
Kenichi Nonaka1*
Koji Maniwa1Chika Takao1Minoru Komura1Yoshinori Mushika1Noriyuki Takeuchi1Toshio Kato1Arizumi Kikuchi2Mitsuhiko Kusakabe1- 1Daiyukai General Hospital, Ichinomiya, Japan
- 2Daiyukai Research Institute for Medical Science, Ichinomiya, Japan
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Background: Gastric cancer with liver metastases is generally associated with poor prognosis, and curative treatment is rarely achieved. Recently, the combination of cytotoxic chemotherapy and immune checkpoint inhibitors (ICIs) has shown promise. However, the efficacy of ICIs in treating microsatellite-stable (MSS) gastric cancer remains controversial. Herein, we present a case of advanced MSS gastric cancer with liver and bulky lymph node metastases, in which combination therapy with S-1 plus oxaliplatin (SOX) and nivolumab led to a pathological complete response. Case Presentation: A 64-year-old man was diagnosed with gastric adenocarcinoma with a solitary liver metastasis (S6) and bulky regional lymph node metastasis. Four cycles of SOX and nivolumab (360 mg every 3 weeks) were administered. Imaging revealed marked tumor regression, and surgery was performed. The patient underwent distal gastrectomy with D2 lymphadenectomy and partial hepatectomy. Pathological evaluation revealed complete tumor regression in the primary lesion, lymph nodes, and liver. The tumor was MSS-and Epstein–Barr virus-negative and had a low tumor mutational burden (TMB). Immunohistochemistry showed a mean CD8+ tumor-infiltrating lymphocyte density of 59.5 ± 14.3 cells per high-power field, a programmed death-ligand 1 (PD-L1) combined positive score (CPS) of ≥ 70% (clone 28-8), and a germline TP53 p.R106C mutation. Conclusion: This case illustrates that even in MSS gastric cancer with low TMB levels, exceptionally high PD-L1 expression may predict a profound response to ICI-based therapy. The PD-L1 CPS may serve as a critical biomarker independent of TMB or microsatellite-instability status.
Keywords: bulky lymph node metastasis, gastric cancer, Immune checkpoint inhibitor, liver metastasis, microsatellite stable, Pathological complete response, PD-L1
Received: 20 Nov 2025; Accepted: 05 Feb 2026.
Copyright: © 2026 Nonaka, Maniwa, Takao, Komura, Mushika, Takeuchi, Kato, Kikuchi and Kusakabe. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Kenichi Nonaka
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