Abstract P1-11-18: The efficacy and safety of trastuzumab and pertuzumab in combination with different chemotherapy regimens for neoadjuvant treatment of HER2-posotive breast cancer: a multi-center real-world study in China

Abstract Background: Dual HER2 targeted therapy with trastuzumab (H) and pertuzumab (P) has been approved as neoadjuvant therapy for patients with HER2-positive breast cancer in China in 2019 based on the results from NeoSphere and PEONY study. However, the real-world efficacy and safety data are currently lack of evidence in China. Therefore, this multi-center real-world study aims to retrospectively analyze the efficacy and safety of neoadjuvant trastuzumab and pertuzumab combined with different chemotherapy regimens of HER2-positive early breast cancer. Methods: Patients received trastuzumab and pertuzumab in combination with different chemotherapy regimens, including taxanes (T), cyclophosphamide (C), anthracyclines (A) were collected retrospectively from 12 centers. The primary endpoint was total pathological complete response (tpCR, ypT0/is ypN0) rate. Results: A total of 357 patients were enrolled, among which 204 (57.5%) recieved TCbHP, 92 (25.9%) recieved EC-THP, and 51 (14.4%) received THP as chemotherapy regimens. The median age was 48 years old (range, 22-76), 142 (39.8%) of patients were classified as hormone receptor (HR)-positive, and 215 (60.2%) were HR-negative. The overall tpCR rate was 58.5% (95%CI, 53.2%-63.7%). tpCR rate for HR-negative patients was significantly higher than HR-positive patients (65.6% vs. 47.9%, p=0.001) and there was not any statistical difference according to chemotherapy regimens (56.9% for TCbHP, 56.5% for EC-THP, and 66.7% for THP, p=0.445). The most common adverse events included anemia (40.1%), white blood cell count decreased (34.3%), ejection fraction decreased (19.5%), Alanine aminotransferase increased (18.9%), platelet count decreased (12.8%) and neutrophil count decreased (12.0%). There was not any toxicity leading to death. Conclusions: Multi-center real-world data show satisfactory tpCR rate and tolerable adverse events of trastuzumab and pertuzumab in combination with different chemotherapy regimens in China. Citation Format: Xiaowei Qi, Hong Hu, chen wenlin, xu yan, liu shu, fang yanman, Taolang Li, ming jia, zhou sihai, chai fan, liang yueyang, fan yuanming, Yi Zhang, Peng Tang, jiang jun, nie jianyun, Li Chen, Shushu Wang. The efficacy and safety of trastuzumab and pertuzumab in combination with different chemotherapy regimens for neoadjuvant treatment of HER2-posotive breast cancer: a multi-center real-world study in China [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-11-18.