Background: There is no clinical evidence supporting the effectiveness of trastuzumab deruxtecan (T-DXd) for treating advanced gastric cancer (AGC) with brain metastasis. Case report: This is a case of a 65-year-old man with human epidermal growth factor-2 (HER2)-positive AGC. He was initially treated with capecitabine, cisplatin, and trastuzumab, followed by paclitaxel and ramucirumab, nivolumab, trifluridine and tipiracil, and irinotecan regimens in addition to radiation therapy for brain metastasis. The patient exhibited refractoriness to the standard regimen used for AGC and developed relapse of the brain metastasis after radiation accompanied by headache, nausea, and dizziness. In August 2020, following the approval of T-DXd for HER2-positive AGC, he received T-DXd therapy. After 5 cycles of T-DXd, contrast-enhanced computed tomography and magnetic resonance imaging demonstrated significant tumor shrinkage and improvement of symptoms. Conclusion: T-DXd demonstrated effectiveness for the treatment of brain metastasis arising from HER2-positive AGC.

背景：没有临床证据支持曲妥珠单抗 deruxtecan (T-DXd) 治疗晚期胃癌 (AGC) 脑转移的有效性。案例报告：这是一例 65 岁男性，人表皮生长因子 2 (HER2) 阳性 AGC。他最初接受卡培他滨、顺铂和曲妥珠单抗治疗，随后是紫杉醇和雷莫芦单抗、纳武利尤单抗、曲氟尿苷和替吡嘧啶，以及伊立替康方案，以及脑转移的放射治疗。患者对用于 AGC 的标准方案表现出顽固性，并在放疗后出现脑转移复发，并伴有头痛、恶心和头晕。2020年8月，T-DXd获批治疗HER2阳性AGC后，接受T-DXd治疗。5 个周期的 T-DXd 后，对比增强计算机断层扫描和磁共振成像显示肿瘤显着缩小和症状改善。结论：T-DXd 证明了治疗 HER2 阳性 AGC 引起的脑转移的有效性。