[The Efficacy of Combined Use of Pertuzumab and Trastuzumab-Based Neoadjuvant Chemotherapy for HER2 Positive Breast Cancer].

NeoSphere trial showed that combined use of pertuzumab and trastuzumab-based chemotherapy for HER2 positive breast cancer improved the rate of pathological complete response (pCR). We retrospectively examined the efficacy of combined use of pertuzumab and trastuzumab-based neoadjuvant chemotherapy for HER2 positive breast cancer. Eleven patients with HER2 positive breast cancer who had completed neoadjuvant chemotherapy and undergone surgery included in this study. Four patients were hormone-receptor-positive and HER2 positive, 7 patients were hormone-receptor-negative and HER2 positive. Ten patients were treated with 4 courses of 5-fluorouracil, epirubicin, and cyclophosphamide (FEC), followed by 4 courses of docetaxel with trastuzumab and pertuzumab (HPD). One patient was treated with 4 courses of HPD. The rate of pCR (ypT0/is and ypN0) was 81.8%, and this outcome was better than the NeoSphere trial and the TRYPHAENA trial. As a result, our study suggested an additional therapeutic effect of 4 courses of FEC followed by 4 courses of HPD.