Ki-67 Index Guided Selection of Preoperative Chemotherapy for HER2-positive Breast Cancer: A Randomized Phase II Trial

Changes in Ki-67 may be a useful predictor of efficacy for preoperative therapy in breast cancer. This randomized Phase II trial will compare standard preoperative chemotherapy comprising paclitaxel and trastuzumab with Ki-67 index guided preoperative chemotherapy in patients with human epidermal growth factor receptor 2-positive operable breast cancer. In the Ki-67 index guided therapy, paclitaxel and trastuzumab were administered initially and the Ki-67 index is evaluated from biopsied specimens after 2 weeks of preoperative chemotherapy. The subsequent chemotherapy regimen is modified according to changes in the Ki-67 index from the start of therapy. If the Ki-67 index is reduced as expected, paclitaxel and trastuzumab are continued. If the Ki-67 index is not reduced as expected, the chemotherapy regimen is changed to epirubicin, cyclophosphamide and trastuzumab. The primary endpoint is the rate of pathological complete response. The secondary endpoints are the objective response rate, disease-free survival and overall survival. Two hundred patients were planned to be accrued.