Neoadjuvant palbociclib on ER+ breast cancer (N007): clinical response and EndoPredict’s value

    1. Masakazu Toi2,6
    1. 1State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technology, Macau SAR, Macao
    2. 2Organisation for Oncology and Translational Research, Hong Kong SAR, China
    3. 3UNIMED Medical Institute, Hong Kong SAR, China
    4. 4Department of Biomedical Statistics and Bioinformatics, Kyoto University Graduate School of Medicine, Kyoto, Japan
    5. 5Department of Pathology, Precious Blood Hospital, Hong Kong SAR, China
    6. 6Breast Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan
    1. Correspondence should be addressed to L W C Chow: lwcchow{at}


    The purpose of the study was to test the efficacy of neoadjuvant palbociclib therapy and to evaluate its impact on cell cycle arrest and changes in EndoPredict (EP) scores before and after treatment. Postmenopausal women with histologically proven ER+ve, HER2−ve invasive breast cancer, 2 cm or greater, were enrolled in an open-label, single-arm study. Twenty eligible patients were given letrozole 2.5 mg per day together with palbociclib 125 mg per day for 3 out of 4 weeks in repeated cycles for 16 weeks (4 cycles) before surgery. The primary end points were clinical response rates (cRR) and preoperative endocrine prognostic index (PEPI). The secondary end points were pathologic response and gene expression testing with EP test on collected tumor samples. The following results were obtained. 17 patients showed a clinical response of 50% or more, including 8 complete responses and 9 partial responses. There was significant reduction in area (P < 0.0001) and volume (P = 0.017) of the cancer. Pathologic complete response (pCR) was achieved in one patient; all cancers were downgraded after treatment. Ki67 (P = 0.044) and EP scores (P < 0.0001) were significantly reduced after treatment. Analysis of the relative gene expression levels showed that all proliferative genes, IL6ST and RBBP8 were decreased after palbociclib treatment. 6 patients with intermediate and three patients with high PEPI risk scores were found to have low EPclin scores. All patients with high PEPI relapse risk score had high EPclin score. In conclusion, effective clinical response was demonstrated by neoadjuvant letrozole in combination with palbociclib. Compared with PEPI, EPclin might be a better parameter to estimate prognosis after neoadjuvant therapy.

    • Received 5 November 2017
    • Accepted 20 November 2017
    • Made available online as an Accepted Preprint 20 November 2017
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    1. Endocr Relat Cancer 25 123-130
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