Abstract P2-13-41: First-line pyrotinib plus trastuzumab and nab-paclitaxel for patients with HER2-positive advanced breast cancer
Authors: Xie Hui , Li Wei , Yao Yufeng , Ni Sujie , Yi Tongbo , Cheng Jinling , Fang Qi , Zhang Lei , Zhou Jun , Wu Xiaohong , Wang Chunbin , Zhang Yanan , Qin Jianwei , Shao Qing , Zhao Tao , Huang Xiaohong , Xu Lingyun 
Published: March 2022

Background: Overexpression of human epidermal factor receptor 2 (HER2) is seen in 15-20% of breast cancer and results in more aggressive clinical behavior and poor prognosis. This study (ChiCTR2000030618) analyzed the efficacy and safety of pyrotinib plus trastuzumab and nab-paclitaxel in patients with previously untreated HER2-positive locally recurrent or metastatic breast cancer.Methods: Patients with previously untreated HER2-positive locally recurrent or metastatic breast cancer received pyrotinib (400 mg, qd), trastuzumab (H, 8 mg/kg loading dose, followed by 6 mg/kg every 3 weeks) and nab-paclitaxel (260 mg/m² every 3 weeks) until disease progression or an unacceptable adverse event (AE). The primary endpoint was progression-free survival (PFS). Secondary endpoints included objective response rate (ORR), disease control rate (DCR), overall survival (OS), and AEs.Results: A total of 28 patients (median age: 55.5 years [28-78]) were enrolled from April 2020 to June 2021. All 28 patients (100%) had Eastern Cooperative Oncology Group performance status of 1. The metastatic sites were in brain (14.29%), liver (25.00%), bone (28.57%) and lung (53.57%). HR+ and HR- for primary tumor accounted for 57.14% and 42.86%, respectively. Trastuzumab was previously administered in the (neo)adjuvant setting to 17(60.71%) patients. Eight patients with measurable lesions were evaluable for response. 5 (62.50%) patients had partial response (PR) and 3 (37.50%) patients achieved stable disease (SD), resulting in an ORR of 62.50% and DCR of 100.00%. Median PFS has not yet been reached. Twenty-one patients were included in the safety assessments. The most common AE was diarrhea (85.71%), but only 3 (14.29%) patients reported Grade ≥ 3 diarrhea which could be well controlled. The median onset of diarrhea was 1.5 days after start of treatment and the median duration was 9 days. Most diarrhea events were reported during the first cycle of treatment and the frequency persistently declined in the following cycles. Moreover, the AEs of all grades that were documented in ≥20% of patients included leukopenia (28.57%), anemia (23.81%), thrombocytopenia (19.05%), γ-glutamyltransferase increased (19.05%), vomiting (19.05%), rash (19.05%) and alanine aminotransferase increased (19.05%). No treatment-related deaths were reported.Conclusion: Pyrotinib plus trastuzumab and nab-paclitaxel showed promising efficacy in first-line HER2-positive breast cancer and were well tolerated. More data would be analyzed and reported in the future.

Citation Format: Hui Xie, Wei Li, Yufeng Yao, Sujie Ni, Tongbo Yi, Jinling Cheng, Qi Fang, Lei Zhang, Jun Zhou, Xiaohong Wu, Chunbin Wang, Yanan Zhang, Jianwei Qin, Qing Shao, Tao Zhao, Xiaohong Huang, Lingyun Xu. First-line pyrotinib plus trastuzumab and nab-paclitaxel for patients with HER2-positive advanced breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-13-41.