LAUSR

1025Background: Pertuzumab (P) provided overall and progression-free survival (PFS) benefits in HER2-positive metastatic breast cancer (MBC) in the CLEOPATRA study as a first-line therapy. However, long-term administration of intravenous docetaxel at a dose of 75 mg/m2 every 3 weeks in MBC patients is difficult. Eribulin (E) is a well-tolerated cytotoxic agent. We report the efficacy and safety of E in combination with trastuzumab (T) plus P as first- and second-line therapy for metastatic or advanced BC in a multicenter, open-label phase II study (UMIN000012232). Methods: HER2-positive advanced or recurrent BC patients with no or a single prior therapy as advanced or recurrent chemotherapy were enrolled. All patients were administered T and taxane as adjuvant or first-line chemotherapy. Treatment consisted of E 1.4 mg/m2 on days 1 and 8 of a 21-day cycle and T (8 mg/kg loading dose > 6 mg/kg) plus P (840 mg loading dose > 420 mg) once every 3 weeks, all given intravenously. The primary end point was PFS....