Abstract P2-13-40: Treatment patterns and adverse events of pyrotinib-based therapy in HER2-positive breast cancer patients in China: Results from a multicenter, real-world study
Authors: Li Yiqun , Tong Zhongsheng , Ouyang Quchang , Wu Xinhong , Li Wei , Cai Li , Yu Zhiyong , Han Zhengxiang , Wang Xiaojia , Li Man , Yang Jin , Li Li , Niu Zhaofeng , Wang Haibo , Wang Qitang , Li Yi , Teng Yuee , Zhu Shiguang , Xu Binghe 
Published: March 2022

Background: Pyrotinib, a newly-developed irreversible pan-ErbB inhibitor, has shown promising antitumor activity and acceptable tolerability in phase 1-3 studies. However, findings from randomized clinical trials may have limited generalizability to patients treated in routine clinical practice. Herein, we conducted this multicenter real-world study to examine the treatment patterns, effectiveness and safety of pyrotinib-based therapy in human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC) patients in China.Methods: This is a China-based, observational study of HER2-positive BC patients receiving pyrotinib-based therapy (NCT04158505). Both early stage and advanced disease were included. Demographics, treatment patterns, and diarrhea management were summarized. The data cutoff date was April 30, 2021, and the study is ongoing to enroll. Real-world progression-free survival (PFS) and overall survival (OS) will be analyzed. Results: Between October 2019 and April 2021, a total of 907 patients (45 in the neoadjuvant setting [median age, 51 years] and 862 in the advanced setting [median age, 54 years]) from 65 sites received at least one dose of pyrotinib. Considering the limited sample size of early stage patients so far, we focused on advanced BC patients in this report. Of 862 patients with advanced disease, 44.2% had visceral metastases, 12.5% had brain metastases, 31.1%, 35.7%, and 33.2% received pyrotinib-based therapy as first-line, second-line, and third- or later-line treatment, respectively. The majority of patients (82.5%) were trastuzumab-exposed, and 10.2% were lapatinib-treated before receiving pyrotinib. Among 744 patients with available treatment information, 75.8% started with standard dose of pyrotinib (400 mg). Pyrotinib plus capecitabine (372 [50.0%]) was the most commonly used regimen for advanced disease, followed by pyrotinib plus chemotherapy other than capecitabine (189 [25.4%]), pyrotinib plus trastuzumab and chemotherapy (100 [13.4%]), and pyrotinib alone (77 [10.3%]). At the time of data cutoff, there were 164 (19.0%) progression or death events in 862 patients with advanced disease, and the median PFS and OS was not mature for the whole population. The median PFS for patients receiving second-line pyrotinib-based therapy was 11.7 months (95% CI, 8.8-not reached). The most common adverse event was diarrhea. Any grade and grade ≥3 diarrhea occurred in 70.5% and 14.9% of 907 patients, respectively. Diarrhea in eight (0.9%) patients with advanced disease were deemed as serious adverse events. Eighty-nine (9.8%) patients received diarrhea prophylaxis, and 436 (48.1%) used antidiarrhea drugs after diarrhea occurred. Montmorillonite powder (6.0% and 33.6%) were the most commonly used drug for both diarrhea prophylaxis and treatment, followed by loperamide (3.9% and 27.9%).Conclusions: In real world, a high percentage of physicians chose to use pyrotinib-based therapy in front lines when treating HER2-positive advanced BC patients, which might maximize its antitumor activity. Diarrhea is manageable in the real-world setting.

Citation Format: Yiqun Li, Zhongsheng Tong, Quchang Ouyang, Xinhong Wu, Wei Li, Li Cai, Zhiyong Yu, Zhengxiang Han, Xiaojia Wang, Man Li, Jin Yang, Li Li, Zhaofeng Niu, Haibo Wang, Qitang Wang, Yi Li, Yuee Teng, Shiguang Zhu, Binghe Xu. Treatment patterns and adverse events of pyrotinib-based therapy in HER2-positive breast cancer patients in China: Results from a multicenter, real-world study [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 P2-13-40.