Phase II study of neoadjuvant weekly nab-paclitaxel and carboplatin, with bevacizumab and trastuzumab, as treatment for women with locally advanced HER2+ breast cancer.

PURPOSE: Neoadjuvant treatment with chemotherapy plus trastuzumab is standard care for women with locally advanced, HER2-positive (HER2(+)) breast cancer. HER2 has been shown to stimulate angiogenesis through vascular endothelial growth factor upregulation. We investigated the feasibility and efficacy of bevacizumab in combination with trastuzumab, nab-paclitaxel, and carboplatin as neoadjuvant therapy for women with locally advanced HER2(+) breast cancer.

PATIENTS AND METHODS: Twenty-eight women with locally advanced HER2(+) breast cancer received nab-paclitaxel (100 mg/m(2) intravenously [I.V.] days 1,8, and 15) and carboplatin (AUC = 6 I.V. day 1) every 28 days × 6 cycles. Concurrent with chemotherapy, trastuzumab (4 mg/kg loading dose, then 2 mg/kg) and bevacizumab (5 mg/kg I.V.) were administered weekly × 23 weeks. Patients then underwent mastectomy or breast-conserving surgery; pathologic responses were assessed. After surgery, trastuzumab 6 mg/kg and bevacizumab 15 mg/kg were administered every 3 weeks (54 weeks total); locoregional radiotherapy and/or antiestrogen therapy was administered per standard guidelines.

RESULTS: Twenty-six patients (90%) completed neoadjuvant therapy, with objective responses in 86%. Pathologic complete response (pCR) was confirmed in 14 of the 26 patients (54%) who had surgery. However, bevacizumab-related complications were common postoperatively and during adjuvant trastuzumab/bevacizumab therapy. Ten patients had wound-healing delays or infections (6 patients discontinued therapy); 4 patients had left ventricular ejection fraction (LVEF) decreases (1 patient discontinued therapy). Other severe treatment-related toxicity was uncommon. Only 9 patients (31%) completed all protocol therapy.

CONCLUSIONS: Neoadjuvant therapy with nab-paclitaxel, carboplatin, trastuzumab, and bevacizumab was feasible in most patients, producing a pCR rate comparable to that in chemotherapy/trastuzumab combinations. In contrast, prolonged bevacizumab/trastuzumab therapy after surgical treatment was not well tolerated, primarily due to bevacizumab-related toxicity. The role of bevacizumab in neoadjuvant therapy remains undefined.