Survival analysis of pyrotinib in HER2-positive metastatic breast cancer: A multicenter real-world study.

e13007 Background: In previous clinical trials, pyrotinib has shown good antitumor activity and manageable toxicity in human epidermal growth factor receptor 2(HER2)-positive metastatic breast cancer (MBC). However, the real-world data on pyrotinib remains limited. In this study, we reported the real-world data on the overall survival (OS) of pyrotinib in HER2-positive MBC for the first time. Methods: This multicenter retrospective study involved 337 HER2-positive MBC patients treated with pyrotinib between October 2016 and October 2024. We updated the analysis of the efficacy and safety of pyrotinib in HER2-positive MBC, including progression-free survival (PFS), OS, objective response rate (ORR), disease control rate (DCR), clinical benefit rate (CBR), and adverse events. Results: As of the data cutoff date of 31 December 2024, the median follow-up duration was 42.0 months (range, 2.0-92.7 months). The median line of treatment was the second, with 19.6% of patients receiving first-line therapy, 54.9% receiving second-line therapy, and 25.5% receiving third-line or above therapy. The overall median PFS was 14.7 (95%CI, 12.6-15.8) months . By treatment line, the median PFS was 21.4 months (95% CI, 10.4–32.3 months) for first-line therapy, 14.6 months (95% CI, 12.0–17.2 months) for second-line therapy, and 10.9 months (95% CI, 8.0–13.7 months) for third-line or above therapy. At the data cutoff, the OS data remained immature. The 3-year OS rate was 58.7% overall, with rates of 69.7%, 64.8%, and 41.8% for first-line, second-line, and third-line or above therapies, respectively. The ORR was 41.5% (95CI%, 35.8%-47.3%), the DCR was 91.2% (95CI%, 87.3%-94.6%), and the CBR was 80.0% (95CI%, 75.4%-84.6%). The most frequent grade 3 or 4 adverse events were diarrhea (21.3%), neutropenia (8.6%), leukopenia (7.9%), hand-foot syndrome (2.5%) and nausea (2.1%). No treatment-related deaths were reported. Conclusions: The updated analysis demonstrated that pyrotinib could be a good treatment option in HER2-positive MBC with acceptable toxicity in the real world. Survival is still under assessment with longer follow-up.