Trastuzumab Combined Oxaliplatin and S-1 Therapy Demonstrated Pathological Complete Response of Synchronous Liver Metastasis of Gastric Cancer

The HER2 positive advanced or metastatic gastric cancer (GC) is recommended with Trastuzumab (Tmab) combined cisplatin (CDDP) and capecitabine (Cap). Otherwise, oxaliplatin (L-OHP) has been replaced in place of CDDP for GC. Furthermore, S-1 is a key oral anticancer drug used in the treatment of gastrointestinal cancer in Asia. A 59year-old man who received Tmab-SOX therapy for solitary synchronous liver metastasis of GC, because the operated intestinal type GC revealed HER2 score 3+ immunohistochemically. Tmab-SOX: (Tmab: 8 mg/kg for first cycle, 90minutes (mins) and 6 mg/kg for subsequent cycles on day 1, 30 mins, L-OHP: 100 mg/m2, day 1, 120 mins, S-1: 80 mg/m2 twice daily, days 1 to 15, orally, every 3 weeks). The solitary liver metastasis shrunk from 28 mm to 13 mm, 4 cycles later. We performed right lobe hepatectomy which specimens’ revealed pathological complete response. Tmab-SOX therapy proved remarkable response and might be an alternative chemotherapy plan against HER2 positive GC.