RT Journal Article SR Electronic T1 Phase II Study of S-1 in Combination with Trastuzumab for HER2-positive Metastatic Breast Cancer JF Anticancer Research JO Anticancer Res FD International Institute of Anticancer Research SP 3583 OP 3588 VO 34 IS 7 A1 TSUTOMU TAKASHIMA A1 TAKAHIRO NAKAYAMA A1 KATSUHIDE YOSHIDOME A1 HIDEMI KAWAJIRI A1 SHUNJI KAMIGAKI A1 JUNJI TSURUTANI A1 TAKASHI ARAI A1 TOSHIKAZU ITO A1 YOSHIHUMI KOMOIKE A1 TAKAKO DOI A1 NORIKAZU MASUDA A1 KEISUKE MIYAUCHI A1 YASUO MIYOSHI A1 JUNICHI SAKAMOTO A1 SATOSHI MORITA A1 TETSUYA TAGUCHI YR 2014 UL http://ar.iiarjournals.org/content/34/7/3583.abstract AB Aim: We undertook a prospective phase II study to evaluate the efficacy of S-1 plus trastuzumab combination regimen for human epidermal-growth factor receptor-2 (HER2)-positive metastatic breast cancer (MBC). Patients and Methods: HER2-positive MBC patients received oral administration of S-1 (80 mg/m2/day, days 1 to 28, every 6 weeks) and intravenous weekly trastuzumab (2 mg/kg), according to the results of a prior Phase I trial of our group. Results: A total of 28 patients were enrolled and received a median of 3.5 (range 1-10) cycles of treatment. Overall response rate and clinical benefit rate were 53.6% and 75.0%, respectively. Progression-free survival was 30 weeks. With regard to grade 3 and 4 adverse effects, leucopenia, neutropenia, increase in serum alanine aminotransferase, and diarrhea were observed. Conclusion: Combination of S-1 and trastuzumab was tolerable and had excellent efficacy with good response and disease control in this trial.