RT Journal Article SR Electronic T1 Phase I Study of Triweekly Nab-Paclitaxel Combined with S-1 in Patients with HER2-negative Metastatic Breast Cancer JF Anticancer Research JO Anticancer Res FD International Institute of Anticancer Research SP 6515 OP 6519 VO 36 IS 12 A1 KOICHI SAKAGUCHI A1 KATSUHIKO NAKATSUKASA A1 TETSUYA TAGUCHI YR 2016 UL http://ar.iiarjournals.org/content/36/12/6515.abstract AB Aim: We conducted a phase I study to determine the maximum tolerated dose (MTD) and recommended dose (RD) of triweekly nanoparticle albumin-bound paclitaxel (nab-paclitaxel) and S-1 combination therapy in patients with human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC). Patients and Methods: This study was carried out with a 3+3 dose escalation design; patients with HER2-negative MBC received nab-paclitaxel at 180-260 mg/m2 on day 1 and S-1 at 65-80 mg/m2 daily on days 1-14, repeated every 3 weeks. Results: The MTD was level 3 (260 mg/m2 nab-paclitaxel with 80 mg/m2 S-1) and the RD was level 2 (260 mg/m2 nab-paclitaxel with 65 mg/m2 S-1). Dose-limiting toxicity was observed in two patients at level 3, who had grade 4 neutropenia and grade 3 myalgia, respectively. Conclusion: The response rate was 66.7%. The clinical benefit rate was 77.8%. Our study shows the efficacy and the feasibility of this combination therapy.