4CPS-126 Analysis of the effectiveness of pertuzumab as neoadyuvant treatment in patients with her2-positive breast cancer

Background According to several neoadjuvant studies, pertuzumab combined with chemotherapy based on trastuzumab is effective in early and advanced HER2-positive breast cancer (BC). Based on the highest rate (51.9%) of complete pathological responses (CpR) (ypT0ypN0) with the combination of pertuzumab and trastuzumab with docetaxel-carboplatin (P-TCH scheme) in the pivotal Tryphaena study we want to analyse the pathological responses in our population. Purpose To analyse the effectiveness of the P-TCH scheme as a neoadjuvant treatment in patients with localised or locally advanced HER2-positive BC. Material and methods Analytical observational study of patients on neoadjuvant chemotherapy treatment by HER2-positive BC, comparing two groups: patients with hormone receptors (HR) positive and negative HR, in a general hospital. Data were obtained from manual and computerised medical records (Selene ® Version 5.3.3) and electronic prescription (Farmis Oncofarm ® Version 3.0.11.38) for a period of 2 years (2015–2017). Effective treatment was considered for the CpR, defined as the absence of residual infiltrating carcinoma at the time of surgery, by pathological anatomy (ypT0ypN0). The variables are expressed as absolute and relative frequencies. Comparisons using Fisher’s exact test. Independent predictors to measure effectiveness are analysed by logistic regression, with odds ratios (OR) being calculated with a 95% confidence interval (CI 95%). Statistical program SPSS Version 23 was used. Results Twenty-six patients were analysed. Mean age 49±3.3 years, all females, with good general status (ECOG 0–1). Seventeen patients (65.4%) had positive HR (oestrogen receptor and/or progestogen positive). The majority (61.5%) had CB located. The two groups were homogeneous. 57.7% (15 patients) had CpR. The independent predictors for effectiveness were: negative HR was 77.8% (seven of nine) (Fisher’s exact test P0.07); BC stratification was localised (53.3%) (Fisher’s exact test P0.4); and complete radiological response after six cycles of chemotherapy was 86.7% (13 of 15) (Fisher’s exact test p Conclusion Double anti-HER2 therapy is effective as a neoadjuvant treatment in patients with HER2-positive CM, with a percentage of responses similar to the pivotal study. The BC stratification did not correlate with the response to treatment, although patients with negative HR showed a higher percentage of CpR. However, it would be necessary to expand the sample to obtain definitive conclusions. Reference and/or Acknowledgements doi:10.1093/annonc/mdt182 No conflict of interest