Immune checkpoint inhibitors (ICIs) are used as salvage treatments for advanced gastric cancer (AGC) regardless of HER2 status. This study assessed the efficacy of ICIs based on HER2 expression in AGC patients who received pembrolizumab as salvage monotherapy at Samsung Medical Center from November 2017 to March 2023. HER2 status was determined via immunohistochemistry, and tumor response and survival outcomes were compared accordingly. Among the 113 patients analyzed, with a median age of 61 years and 64.6% being male, 12 patients (10.6%) were HER2-positive, and 101 patients (89.4%) were HER2-negative. Of 92 evaluable patients, none had a complete response. However, 50% of HER2-positive patients had a partial response, compared to 4.9% of HER2-negative patients (p< 0.001). The disease control rate was 70% in HER2-positive and 37.8% in HER2-negative patients (p= 0.086). Median progression-free survival was 5.53 months for HER2-positive patients versus 1.81 months for HER2-negative patients (p= 0.037). Pembrolizumab as a salvage chemotherapy for the treatment of AGC demonstrated superior effectiveness in HER2-positive patients compared with HER2-negative patients.
免疫检查点抑制剂（ICIs）被用作晚期胃癌（AGC）的挽救性治疗，无论其HER2状态如何。本研究评估了2017年11月至2023年3月期间在三星医疗中心接受帕博利珠单抗作为挽救性单药治疗的AGC患者中，基于HER2表达的ICIs疗效。HER2状态通过免疫组织化学法确定，并据此比较肿瘤反应和生存结局。在分析的113名患者中，中位年龄为61岁，64.6%为男性，其中12名患者（10.6%）为HER2阳性，101名患者（89.4%）为HER2阴性。在92名可评估患者中，无人达到完全缓解。然而，50%的HER2阳性患者出现部分缓解，而HER2阴性患者中仅有4.9%（p<0.001）。疾病控制率在HER2阳性患者中为70%，在HER2阴性患者中为37.8%（p=0.086）。HER2阳性患者的中位无进展生存期为5.53个月，而HER2阴性患者为1.81个月（p=0.037）。作为晚期胃癌的挽救性化疗药物，帕博利珠单抗在HER2阳性患者中显示出优于HER2阴性患者的疗效。
The Impact of Pembrolizumab as a Salvage Therapy Based on HER2 Expression in Advanced Gastric Cancer
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