Paclitaxel, Trastuzumab, and Pertuzumab in the Treatment of Metastatic HER2-Positive Breast Cancer

The regimen will consist of paclitaxel (80 mg/m2) weekly + trastuzumab every 3 weeks (8 mg/kg loading dose → 6 mg/kg every 3 weeks) + pertuzumab every 3 weeks (840 mg as a loading dose → 420 mg), all given intravenously (IV). Patients may be given trastuzumab weekly in lieu of every 3 weeks (4 mg/kg loading dose → 2 mg/kg every 3 weeks). Patients will be on treatment until progression of disease.