Phase II neoadjuvant trial of albumin-bound paclitaxel, trastuzumab and pertuzumab followed by anthracycline based regimens in patients with operable HER2 positive breast cancer (OMC-BC05).

Abstract

e12594 Background: Anthracycline and Taxane have been widely used and studied in neoadjuvant setting for treatment of locally advanced breast cancer. Various regimens have explored the addition of newer agents to determine safety and efficacy, and pathological complete response(pCR) has been demonstrated to be associated with favorable overall survival in primary breast cancer. Pertuzumab increases the rate of pathological complete response in the preoperative context and increases overall survival among patients with metastatic disease when it is added to Trastuzumab and chemotherapy for the treatment of human epidermal growth factor receptor 2 (Her2)-positive breast cancer. In addition, APHINITY trial showed that Pertuzumab significantly improved the rates of invasive-disease-free survival among patients with HER2-positive, operable breast cancer when it was added to Tastuzumab and chemotherapy. We conducted a clinical phase II neoadjuvant trial of nab-Paclitaxel, Trastuzumab and Pertuzumab followed by Anthracycline Based Regimens in Patients with Operable Her2 Positive Breast Cancer. Methods: The study is designed to evaluate nab-paclitaxel, Trastuzumab and Pertuzumab followed by EC or AC or FEC as neoadjuvant therapy in patients with Her2 positive operable breast cancer. Patients are treated with neoadjuvant nab-paclitaxel(260 mg/m2 ), Trastuzumab and Pertuzumab followed by EC(Epirubicin 90 mg/m2 , Cyclophosphamide 600 mg/m2) or AC(Doxorubicin 60 mg/m2 , Cyclophosphamide 600 mg/m2) or FEC(Fluorouracil 500mg/m2, Epirubicin 100 mg/m2 , Cyclophosphamide 500 mg/m2 ) q21d x 4. Patients undergo surgery 4-6 weeks later from completing chemotherapy. The primary endpoint, pCR is defined as no evidence of invasive tumors in the final surgical sample both in the breast and axillary lymph nodes. Secondary endpoints include overall response rate, disease-free survival, rate of breast conserving surgery, histological response rate, rate of sensory neuropathy ant the safety of the treatment. Results: In 30 evaluable patients, the pCR rate was 50%; 6/19 (31.6%) in ER-positive and 9/11 (81.8%) in ER-negative, 1/7 (14.3%) in IHC 2+, FISH positive and 14/23 (60.9%) in IHC 3+ . Of the study treatments, the most frequent reason for delay or dose reduction was hematologic toxicity; no patient required a dose reduction for nab-PTX because of peripheral neuropathy. Conclusions: Neoadjuvant treatment using albumin-bound Paclitaxel, Trastuzumab and Pertuzumab followed by Anthracycline based regimens appears to be effective especially in pure HER2 type or IHC 3+ cases.