Multicenter phase II study of trastuzumab with S-1 alone in elderly patients with HER-2 positive advanced gastric cancer (JACCRO GC-06).

106 Background: S-1 plus cisplatin (SP) is a standard regimen for advanced gastric cancer (AGC) in East Asia. In patients with HER2-positive AGC, ToGA trial showed survival benefit with the addition of trastuzumab to capecitabine plus cisplatin or fluorouracil plus cisplatin and HERBIS-1 trial demonstrated promising antitumor activity with the addition of trastuzumab to SP. However, cisplatin has several important drawbacks, including nausea, vomiting, and renal toxicity. And these disadvantages of cisplatin are noticeable in elderly patients. We evaluated the efficacy and safety of trastuzumab combined with S-1 alone in elderly patients with HER-2 positive AGC. Methods: Patients, 65 years or older, with HER2-positive AGC received S-1 (80–120mg per day) orally on days 1–28 of a 42-day cycle and trastuzumab (course 1, 8 mg/kg; course 2 onward, 6 mg /kg) intravenously on day 1 of a 21-day cycle. The primary end point was response rate (RR); secondary endpoints were overall survival (OS), progression free su...