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Clinical studies have confirmed that nab-paclitaxel(nab-PTX)therapy is effective and safe in patients with metastatic breast cancer. Neoadjuvant chemotherapy(NAC) with nab-PTX has resulted in a pathological complete response (pCR) rate of 29% in all cases and 58% in HER2-positive cases. However, these data were obtained from an overseas study, and the effectiveness and safety of NAC with nab-PTX remain unclear in Japan. Thus, the present study was conducted to investigate these aspects. In patients with T1-3, N0-2, M0 breast cancer, 4 cycles of 260 mg/m2 nab-PTX were administered every 3 weeks after 4 cycles of EC therapy(100 mg/m2 of epirubicin and 600 mg/m2 of cyclophosphamide)as NAC. In HER2- positive patients, trastuzumab was used in combination with nab-PTX. Overall, 14 patients were registered between October 2014 and October 2018. One patient who had requested for another drug after providing informed consent was excluded, and the remaining 13 patients were analyzed. The primary endpoint was pCR rate. The median age of the subjects was 57 years, and the median tumor diameter was 35 mm. There were 7 cases of Stage Ⅱ disease and 6 cases of Stage Ⅲ disease. As for tumor subtype, there were 7 cases of Luminal-type, 2 cases of Luminal- HER2-type, 4 cases of HER2-type, and no triple negative-type tumors(the cut-off values for estrogen receptor [ER] and progesterone receptor were both 1%). The objective response rate to NAC was 77%(10/13 cases), and no PD was observed. The pCR rate was 54%(7/13 cases): 2 patients had Luminal-type tumors, 1 had a Luminal-HER2-type tumor, and 4 had HER2-type tumors. Predictive factors for pCR were ER negativity and HER2 positivity. Common adverse events of chemotherapy were hair loss, pain, malaise, anemia, dysgeusia, constipation, itchiness, and numbness, but their severity was modest, and they were manageable. This study suggests the efficacy and safety of nab-PTX after EC therapy in Japanese patients with operable breast cancer.

Background: Matrix-producing breast carcinoma (MPBC) is a very rare and usually aggressive triple-negative breast cancer. We successfully established a patient-derived orthotopic xenograft (PDOX) model from a patient with MPBC and used it to study tumor sensitivity to various agents., Case Report: A 40-year-old woman was diagnosed with MPBC with a triple-negative phenotype. Due to axillary lymph-node metastases found during radical mastectomy, the patient was subsequently treated with epirubicin, cyclophosphamide and paclitaxel. In addition, radiotherapy was directed to the chest wall and subclavicular fossa. A portion of the cancer tissue from the mastectomy was used to establish a PDOX nude-mouse model. The PDOX model was resistant to paclitaxel, bevacizumab, vinorelbine, cisplatinum and olaparib, and sensitive to eribulin. Metastases in mediastinal lymph nodes and the right ovary were observed in the patient 14 months after mastectomy. Thoracoscopic mediastinal lymph-node biopsy and laparoscopic oophorectomy were performed, and both confirmed breast-cancer metastasis. The patient was then treated with paclitaxel and bevacizumab but no response was observed, which correlated with the inability of these drugs to arrest tumor growth in the PDOX models of the patient's tumor. The patient was then given eribulin based on the PDOX-model result, but treatment had to be stopped because of rapid progression of metastasis into the cervical lymph nodes and thyroid gland. The patient was subsequently treated with atezolizumab and nab-paclitaxel. Unfortunately, the patient died of her cancer 8 months after recurrence., Conclusion: The present study demonstrates that the PDOX model of a patient's triple-negative MPBC accurately predicted that paclitaxel and bevacizumab would not arrest the patient's tumor growth. Eribulin may have been effective if administered at an earlier stage of the patient's cancer course. Drug-screening results from PDOX models should be used as early as possible in order to improve patient outcome., (Copyright © 2021 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)