Pyrotinib-based therapy for patients with HER2-positive breast cancer: A multicenter, real-world study.

Abstract

1040 Background: Pyrotinib, an irreversible pan-ErbB inhibitor, has been approved for the treatment of HER2-positive advanced breast cancer in China. Real-world data is instructive for effect evaluation and application of the drug in clinical practice. Herein, this study was conducted to evaluate the effectiveness and safety of pyrotinib-based therapy in patients with HER2-positive breast cancer in the real-world setting. Methods: In this retrospective, multicenter, real-world study, data of patients with HER2-positive breast cancer who received pyrotinib-based therapy from 19 sites were reviewed. Disease characteristics, prior therapies, and treatment patterns were summarized. Progression-free survival (PFS) and the incidence of diarrhea were analyzed. Results: Between September 2018 and June 2021, a total of 378 patients with HER2-positive advanced breast cancer were included. Of 378 patients, 47.4% had hormone receptor (HR)-positive disease, 41.3% had HR-negative disease, and 11.4% had unknown HR status. Brain, lung, liver, and bone metastases were found in 24.9%, 35.7%, 31.7%, and 33.1% of all cases, respectively. Most of patients (83.1%) were trastuzumab-exposed, 12.7% were pertuzumab-exposed, and 8.2% had been treated with lapatinib or neratinib before receiving pyrotinib. Pyrotinib plus chemotherapy (211 [55.8%]) was the most commonly used regimen, followed by pyrotinib monotherapy (115 [30.4%]), pyrotinib plus trastuzumab and chemotherapy (29 [7.7%]), other regimens (18 [4.8%]), and unknown regimen (5 [1.3%]). Standard dose (400 mg once daily) was used in 256 (67.7%) patients. With a median follow-up duration of 20.5 months, the median PFS was 13.0 months (95%CI, 12.0-14.0). Further analyses showed that the median PFS did not differ in subgroups by age (≥65 or < 65 years), HR status (positive or negative), brain metastasis (yes or no), lung metastasis (yes or no), liver metastasis (yes or no), bone metastasis (yes or no), prior exposure to trastuzumab (yes or no), treatment regimen (pyrotinib monotherapy or combination therapy). Significant variance was discovered between sufficient dosage group and non-sufficient group (13.2 months vs 10.93 months, p= 0.028). The survival advantage of sufficient dosage was also evident in brain metastasis cases (14.4 months vs 8.3 months, p= 0.043).The most common adverse event was diarrhea (85.7%), and grade ≥3 diarrhea occurred in 18.5% of patients. Diarrhea was the leading cause for does reduction of pyrotinib. Conclusions: The PFS data in our study was similar to previous clinical trials referring to HER2-positive advanced breast cancer treated with pyrotinib. Cases with brain metastasis also displayed a satisfactory survival result. Sufficient dosage is of great importance for prolonged survival, prevention of diarrhea may efficiently avoid does reduction and guarantee the drug efficacy.