Abstract P6-17-31: Real world evidence of neoadjuvant treatment based on dual blockade with pertuzumab plus trastuzumab for early HER2+ breast cancer: The NeoPETRA study
Authors: Chacón JI , Saura C , Ciruelos E , Alonso JI , de la Morena P , Santisteban Eslava M , Gallegos I , de Luna A , Dalmau E , González-Santiago S 
Published: May 2019

Background: Evidence from clinical trials supports the neoadjuvant use of pertuzumab and trastuzumab with chemotherapy to improve the pathologic complete response (pCR) in early HER2+ breast cancer (BC), but information on the efficacy of this combination in the clinical practice setting is still limited. In order to widen its real-world data (RWD), we conducted an observational study to determine the pCR rate obtained in routine clinical practice.

Methods: This was a multicenter, retrospective, observational study in patients (pts) with early HER2+ BC who received neoadjuvant therapy based on dual blockade with pertuzumab and trastuzumab. All data were retrospectively collected from pts medical charts. The primary study objective was the total pCR rate (ypT0/is ypN0). Secondary objectives included patient characteristics, neoadjuvant treatment patterns with the dual blockade, surgery types, breast pCR rate (ypT0is), and neoadjuvant safety profile.

Results: Two hundred and forty-three evaluable pts treated in Spain between November 2013 and September 2017 were enrolled between October 2017 and February 2018 (median age [range] 51.7 [44.7-60.2] years; postmenopausal 47.7%; ECOG 0/1 88.9/10.6%; stage II/III tumors 54.3/28.7%; hormone receptor-positive 62.4%). The most common neoadjuvant chemotherapies used were taxanes+anthracyclines (n=180, 74.1%), platinum-based chemotherapies (n=35, 14.4%), and taxanes (n=27, 11.1%). Response rates (radiologic/clinical assessments) before surgery were: complete response 62.1% (n=151), partial response 33.3% (n=81), stable disease 4.1% (n=10), and non-evaluable 0.4% (n=1). Breast-conserving surgery (tumorectomy/lumpectomy and quadrantectomy) was performed in 57.8% (n=133) pts and not conserving (simple, radical and modified radical mastectomy) in 42.2% (n=97). The total pCR was 66.4% and breast pCR was 67.6%. Total pCR in the breast was achieved by 80.7% (n=67) hormone receptor-negative and 56.3% (n=76) hormone receptor-positive pts (statistically significant differences; p&lt;0.001). According to neoadjuvant treatment, total pCR in the breast was achieved by 71.0% (n=120) taxanes+anthracyclines, 48.6% (n=17) platinum-based chemotherapies, and 59.3% (n=16) taxanes users (statistically significant differences; p=0.028). Sixty-three (35.0%) pts experienced at least one adverse reaction (AR) to pertuzumab/trastuzumab+taxanes+anthracyclines (grade 3 ARs: asthenia 0.6%, diarrhea 2.2%, febrile neutropenia 1.1%, and neutropenia 1.1%; grade 4 AR: neutropenia 0.6%), 3 (8.6%) to pertuzumab/trastuzumab+platinum-based chemotherapies, and 22 (11.1%) to pertuzumab/trastuzumab+taxanes (grade 3 AR: diarrhea 3.7%).

Conclusions: This is the first, to the best of our knowledge, multicenter observational study to determine the pCR rate obtained in routine clinical practice in Spain. Results obtained from it have been remarkable: neoadjuvant therapy based on dual blockade with pertuzumab and trastuzumab for HER2+ BC in the routine clinical practice setting enabled the achievement of total pCR rates over 66%, which are even higher than those obtained in previous clinical trials. In addition, this therapy has showed an acceptable safety profile, in line with previous assessments.

Citation Format: Chacón JI, Saura C, Ciruelos E, Alonso JI, de la Morena P, Santisteban Eslava M, Gallegos I, de Luna A, Dalmau E, González-Santiago S. Real world evidence of neoadjuvant treatment based on dual blockade with pertuzumab plus trastuzumab for early HER2+ breast cancer: The NeoPETRA study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-17-31.