Different Pcr Rates According Pam50 Defined Subtypes In Her2 Positive Early Breast Cancer Treated With Neoadjuvant Pertuzumab And Trastuzumab.

e12634Background: We aim to compare the benefit of adding pertuzumab (P) to the standard neoadjuvant treatment with trastuzumab (T) in patients (pt) with early immunohistochemically (IHC) defined HER2+ breast cancer (BC) in the different intrinsic molecular subtypes defined by PAM50 gene expression analysis. Methods: 219 pt. with IHC HER2+ BC, stage I-IIIC, diagnosed in 8 Spanish hospitals were consecutively treated with neoadjuvant chemotherapy (NAC) + antitargeted HER2 therapy. Cohort A (n128) received NAC+T and Cohort B (n91) received NAC+T+P. Patients were classified into intrinsic molecular subtypes based on the PAM50 signature. Rate of pathologic complete response in breast and axilla (pCR) in the different subtypes was compared by ChiSquared test. A multivariate logistic regression model was used to analyze the potential effects of the covariates over the pCR rates. Results: Characteristics of the patients and intrinsic molecular subtypes are shown in Table 1. The overall pCR rate was significantly...