A phase II prospective study of the trastuzumab combined with 5-weekly S-1 and CDDP therapy for HER2-positive advanced gastric cancer

Background We evaluated the efficacy and safety of 5-weekly S-1 and cisplatin combined with trastuzumab, a monoclonal antibody against human epidermal growth factor receptor type 2 (HER2) for HER2-positive advanced gastric cancer (AGC). Methods This phase II study treatment consisted of S-1 (80-120 mg per day) orally on day 1-21, cisplatin (60 mg/m(2)) intravenously on day 8, and trastuzumab (8 mg/kg on day 1 of the first cycle, followed by 6 mg/kg every 3 weeks) intravenously. The primary end point was 1-year survival rate. The secondary end points included overall survival, progression-free survival (PFS), response rate (RR), and safety. Results A total 22 patients from seven centers were enrolled. In the 20 patients evaluable for analysis, the 1-year survival rate was 70 % (95 % confidence interval (CI) 49.9-90.1 %), and median survival time, PFS, and RR were 15.3, 7.5 months and 41.2 %, respectively. Major grade 3/4 adverse events were neutropenia (30 %), anorexia (30 %), leukopenia (25 %), fatigue (20 %), and anemia (15 %). Conclusions Five-weekly S-1 and cisplatin combined with trastuzumab showed effective with favorable safety profile in patients with HER2-positive AGC.