Abstract P1-12-11: Real-world incidence and management of diarrhea secondary to pyrotinib in patients with HER-2 positive breast cancer
Authors: Liu Hong , Ma Li , Wang Xu , Chang Xinzhong , Yu Qi , Huang Qingfeng , Hao Chunfang , Liu Jun , Zhao Jing , Li Shufen , Tong Zhongsheng , Shi Yehui , Lu Ning , Zhao Weipeng , Wang Tong , Cao Xuchen , Wang Chen , Liu Juntian , Zhao Ying , Zhang Lina , Guo Baoliang , Wang Xin , Di Xu , Gao Chunhui , Liu Zongzhan , Sun Shuo , Li Linwei 
Published: March 2023

Objective: Pyrotinib, an oral irreversible pan-HER receptor tyrosine kinase inhibitor, showed promising efficacy and manageable safety profiles in the treatment of HER-2 positive breast cancer. Diarrhea is the most common adverse event associated with pyrotinib. This study aimed to evaluate the incidence and management of diarrhea secondary to pyrotinib in Chinese patients with HER-2 positive breast cancer.

Methods: In this prospective real-world study, consecutive patients aged over 18 with HER-2 positive breast cancer and an Eastern Cooperative Oncology Group performance status (ECOG PS) of 0-2 who planned to receive pyrotinib-based regimens for at least 21 days were included. Pyrotinib-treated patients and those with preexisting gastrointestinal conditions were excluded. There were no planned management strategy or primary prophylaxis for diarrhea, while loperamide, montmorillonite powder or Golden Bifid (a live combined Bifidobacterium, Lactobacillus and Streptococcus Thermophilus tablet) were recommended. Treatment was given in accordance with routine clinical practice by investigators. For patients developed grade 3 or higher diarrhea, pyrotinib was suspended until the diarrhea improving to grade 1 or less, and secondary prophylaxis (such as loperamide, loperamide plus montmorillonite powder, or loperamide plus Golden Bifid) was administrated before pyrotinib resumption. The baseline characteristics of patients and details of diarrhea (onset time, duration, severity according to the National Cancer Institute-Common Terminology Criteria for Adverse Events version 4.03, treatment and prognosis) were collected.

Results: Between August, 2020 and April, 2022, a total of 107 eligible patients were included, with a median age of 54 (range: 25-81) years old. Most patients (93.5%) had an ECOG PS of 0-1, and 51 patients (47.7%) were hormone receptor positive. A total of 46 patients (43.0%) received pyrotinib in the early stage and 61 (57.0%) in the advanced stage. Sixty-nine cases (64.5%) used pyrotinib-containing combination therapy (including 40 combined with capecitabine, 13 combined with trastuzumab, and 16 combined with other regimens), and 38 (35.5%) received pyrotinib alone. Ninety-eight cases (91.6%) reported diarrhea of any grade. Grade 1, 2 and 3 diarrhea occurred in 78 (72.9%), 9 (8.4%) and 11 (10.3%) patients, respectively. The median time to first onset of diarrhea of any grade was 2.5 (1-12) days, and the duration of first onset was 4 (1-24) days. The cumulative duration of diarrhea was 10 (1-60) days. Sixty-four, two, thirty, two patients used loperamide alone, montmorillonite powder alone, loperamide plus montmorillonite powder and loperamide plus Golden Bifid for the treatment of diarrhea, respectively. Eleven (10.3%) and seven (6.5%) patients experienced pyrotinib dose reduction and pyrotinib discontinuation. For 11 patients suffered grade 3 diarrhea, the median time to first onset of grade 3 diarrhea was 9 (4-14) days. Two, four and five patients administrated loperamide, loperamide plus Golden Bifid and loperamide plus montmorillonite powder as their secondary prophylaxis. Ten of eleven had grade 1 or 2 diarrhea after secondary prophylaxis, while one patient still suffered grade 3 diarrhea. All of them (11/11) held the pyrotinib dose. The incidence rate of constipation of all patients was 3.7%, which did not increase after treatment or secondary prophylaxis for diarrhea.

Conclusion: In this study, the majority of patients developed pyrotinib associated diarrhea, and most of them were grade 1. About 10% patients reported grade 3 diarrhea, which can be managed by loperamide-based treatment and secondary prophylaxis.

Table 1. Baseline characteristics of patients ECOG PS: Eastern Cooperative Oncology Group performance status; HER-2: human epidermal growth factor receptor 2.

Table 2. Summary of patients developed diarrhea

Table 3. Summary of patients developed grade 3 diarrhea

Citation Format: Hong Liu, Li Ma, Xu Wang, Xinzhong Chang, Qi Yu, Qingfeng Huang, Chunfang Hao, Jun Liu, Jing Zhao, Shufen Li, Zhongsheng Tong, Yehui Shi, Ning Lu, Weipeng Zhao, Tong Wang, Xuchen Cao, Chen Wang, Juntian Liu, Ying Zhao, Lina Zhang, Baoliang Guo, Xin Wang, Xu Di, Chunhui Gao, Zongzhan Liu, Shuo Sun, Linwei Li. Real-world incidence and management of diarrhea secondary to pyrotinib in patients with HER-2 positive breast cancer [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 P1-12-11.