# Pathological Complete Response after Surgery following Chemotherapy with Immune Checkpoint Inhibitors for Gastric Cancer with Liver Metastases: Two Case Reports

## TL;DR

Two patients with advanced gastric cancer and liver metastases achieved complete tumor removal after chemotherapy and immune therapy, showing promising results for this treatment approach.

## Contribution

Demonstrates the potential of combining chemotherapy and immune checkpoint inhibitors followed by surgery for advanced gastric cancer with liver metastases.

## Key findings

- Both patients achieved a pathological complete response after treatment with SOX and nivolumab followed by surgery.
- No residual tumor was found in the primary or liver lesions in both cases.
- Patients remained recurrence-free for 5 and 6 months post-surgery, respectively.

## Abstract

In recent years, advances in pharmacotherapy, including the introduction of immune checkpoint inhibitors (ICIs), have affected treatment strategies for advanced gastric cancer. Surgical intervention after systemic therapy has the potential to improve the prognosis of patients with advanced gastric cancer and liver metastases. Herein, we report two cases in which gastrectomy and hepatectomy were performed after pharmacotherapy with ICIs, resulting in a pathological complete response.

Case 1 was a 75-year-old man diagnosed with gastric cancer causing stenosis from the antrum to the duodenal bulb. Contrast-enhanced CT revealed a 3.2 cm liver metastasis with a tumor thrombus in the right portal and posterior sectoral branches. The patient was diagnosed with cT4aN+M1(HEP) Stage IVB gastric cancer and received four courses of S-1 plus oxaliplatin (SOX) and nivolumab. Marked tumor shrinkage led to surgery, including distal gastrectomy and posterior segmentectomy. Pathological examination revealed no residual tumor in the primary or liver lesions, with a histological grade 3 response. Postoperatively, S-1 and nivolumab were initiated, and the patient remained recurrence-free for 5 months. Case 2 was a 77-year-old man who was diagnosed with gastric cancer during screening. Contrast-enhanced CT revealed a 2.2 cm liver metastasis in segment 8. A diagnosis of cT4aN+M1(HEP) stage IVB disease was made, and he received four courses of SOX and nivolumab preoperatively. After tumor shrinkage, total gastrectomy and S8 partial hepatectomy were performed. Pathological examination revealed no residual tumor in the primary or liver lesions, with a histological grade 3 response. Postoperatively, S-1 and nivolumab were initiated, and the patient remained recurrence-free for 6 months.

Curative resection following pharmacotherapy with ICIs may represent a potential treatment strategy for gastric cancer with liver metastases. Further case reports are required to evaluate the safety and long-term outcomes of surgery following systemic therapy.