Neoadjuvant Pertuzumab-containing Regimens Improve Pathologic Complete Response Rates in Stage II to III HER-2/neu-positive Breast Cancer: A Retrospective, Single Institution Experience

Our findings show the efficacy of pertuzumab and trastuzumab-containing regimens compared with trastuzumab-containing regimens with regard to achieving pathologic complete response in over 900 patients with stage II to III human epidermal growth factor 2 (HER2)-positive breast cancer, emphasizing the effect of incorporating an additional anti-HER2 targeted agent into modern neoadjuvant therapy for HER2-positive breast cancer in clinical practice. Introduction: Several human epidermal growth factor 2 (HER2)-targeted regimens are used to treat HER2-positive (HER2 ⁺ ) breast cancer (BC). The goal of this study was to retrospectively determine the pathologic complete response (pCR) rate for trastuzumab and pertuzumab (HP)-containing regimens compared with trastuzumab (H)-containing regimens for stage II to III HER2 ⁺ BC. Patients and Methods: Patients (n = 977) with stage II to III HER2 ⁺ BC who received neoadjuvant HER2-targeted therapy from 2005 to 2016 and underwent definitive breast and axillary lymph node surgery were identified. pCR was defined as ypT0/is, ypN0. Univariate/multivariate logistic regression and the χ ² test for comparing proportions was used for the statistical analysis. Results: The pCR rate was higher for the HP group (n = 170) compared with the H group (n = 807): 59% versus 46% (odds ratio, 1.7; 95% confidence interval, 1.21-2.37; P =.0021). After adjustment for clinically important factors (age, date of diagnosis, stage, tumor grade, nodal status, hormone receptor [HR] status, menopausal status, and chemotherapy backbone) the adjusted odds ratio was 2.25 (95% confidence interval, 1.08-4.73; P =.032). In multivariate analysis, a significant predictor of pCR in both groups included HR status (HR-negative > HR-positive). Conclusion: These results demonstrate that HP-containing regimens yield higher pCR rates compared with H-containing regimens in patients with stage II to III HER2 ⁺ BC in clinical practice regardless of chemotherapy backbone.