Efficacy and safety of pyrotinib‐containing regimen in the patients with HER2‐positive metastatic breast cancer: A multicenter real‐world study

BACKGROUND: Pyrotinib, a novel irreversible epidermal growth factor receptor 2 (EGFR)/HER2 dual tyrosine kinase inhibitor, has shown promising antitumor efficacy with tolerable toxicity in HER2‐positive metastatic breast cancer (MBC) in several clinical trials. However, the clinical trials do not usually well reflect the patients in real clinical settings. Despite several small‐sample studies in real world, the data on pyrotinib as first‐line and third‐or‐later‐line treatment and the efficacy comparison of pyrotinib combined with different regimens are still lacking. Therefore, this study aimed to investigate the efficacy and safety of pyrotinib for the HER2‐positive MBC in real world to replenish more comprehensive data. METHODS: A total of 172 HER2‐positive MBC patients treated with pyrotinib‐based therapy were recruited from multiple centers in nonclinical trial settings from September 2017 to June 2020. RESULTS: The median progression‐free survival (mPFS) of 172 patients was 8.83 months. The patients, receiving first‐line pyrotinib treatment, had the longest mPFS (20.93 months) compared with those receiving second‐line (8.67 months, p = 0.0339) and third‐or‐later‐line (7.13 months, p = 0.0075) treatments, respectively. Prior treatment with lapatinib (p = 0.012) and site of metastasis (visceral vs. nonvisceral) (p = 0.033) were the independent prognostic factors for PFS. The prior treatment with lapatinib compared with lapatinib‐native treatment (5.96 vs. 10.97 months, p = 0.0036) and those with visceral metastasis compared with nonvisceral metastasis (8.40 vs. 23.70 months, p = 0.0138) had worse mPFS. Among 146 patients evaluated for efficacy, 2.1%, 58.9%, and 32.9% showed complete response, partial response, and stable disease, respectively. Adverse events occurred in 92.4% of the patients with 33.3% Grade 3 and higher adverse events and diarrhea (57.0%), anemia (44.8%), and leukopenia (40.7%) as the most frequent ones. CONCLUSIONS: Pyrotinib‐containing regimen could effectively treat HER2‐positive MBC with acceptable toxicity, including the patients who progressed after lapatinib treatment and with brain metastasis.