Multicenter phase II study of capecitabine plus cisplatin as first-line therapy for human epidermal growth factor receptor 2-negative advanced gastric cancer: Yokohama Clinical Oncology Group Study YCOG1107

S-1 plus cisplatin therapy is the recommended standard first-line regimen for human epidermal growth factor receptor 2 (HER-2)-negative advanced unresectable or recurrent gastric cancer (AGC) in the Japanese Gastric Cancer Treatment Guidelines. By contrast, capecitabine plus cisplatin (XP) therapy has been second-line therapy for these patients. This prospective study aimed to evaluate the efficacy and safety of XP as a first-line regimen for HER2-negative patients with AGC. In this multicenter, open-label, phase II study, patients received cisplatin (80 mg/m(2) i.v. day 1) plus capecitabine (1000 mg/m(2) orally, twice daily, days 1-14) at 3 week intervals until disease progression or non-continuation for various reasons. The primary endpoint was overall response rate; secondary endpoints included progression-free survival (PFS), overall survival (OS), and toxicity profiles. Thirty-six patients with HER2-negative AGC were enrolled in this study. Of these, 16 patients with evaluable lesions were assessable for efficacy and 36 were assessable for toxicity. One patient achieved a complete response and five partial responses. The overall response rate was 37.5% [95% confidence interval (CI) 13.7-61.2%] calculated on an intention-to-treat basis. The median PFS and median OS were 5.2 months (95% CI 4.2-6.2 months) and 16.9 months (95% CI 5.8-27.9 months), respectively. Treatment-related adverse events were generally mild; the most common grade 3/4 adverse event was neutropenia (27.8%), followed by anorexia (19.4%), leucopenia (16.7%), anemia (16.7%), and nausea (13.9%). XP as first-line therapy is effective and well tolerated by patients with HER2-negative AGC.