A Retrospective Real-World Study of Pyrotinib in HER-2 Positive Advanced Breast Cancer.

Purpose: To explore the efficacy and safety of pyrotinib in a real-world setting in a population with HER2-positive advanced breast cancer, subgroup analysis was conducted based on different clinicopathological features to further explore the general characteristics of patients, tumor nature, and the effect of various lines of treatment before patients started pyrotinib on the efficacy of pyrotinib in the real-world study.

Methods: The clinical pathological characteristics, drug efficacy and related adverse reactions of HER2-positive MBC patients treated with pyrotinib in six hospitals in Southeast Zhejiang Province from February 2018 to December 2023 were collected and analyzed retrospectively.

Results: A total of 342 patients with HER2-positive MBC were enrolled. The median follow-up time of 42.0 months. The median age of the overall population was 52 years (range from 25-90 year old). Median progression-free survival in the total population was 10.0 months, the median overall survival was 29.0 months. The (objective response rate, ORR) was 40.35% and the (disease control rate, DCR) was 83.92%. The median progression-free survival (PFS) in the total population was 10.0 months, the median overall survival was 29.0 months. And pyrotinib had better mPFS for advanced first-line treatment than for second-third-line and beyond(14.0 months vs.10.0 months vs.6.0 months, P<0.001). Multivariate Cox regression analysis showed that ECOG, HER2 status, brain metastasis, liver metastasis, number of pyrotinib treatment lines, previous lapatinib treatment, combined capecitabine therapy and trastuzumab resistance were independent prognostic factors for PFS. Diarrhea was the most common adverse reaction (ADR) in 205 patients (59.94%), which could be controlled by antidiarrheal drugs.

Conclusion: This multicenter study suggested that the use of pyrotinib for HER2 positive MBC had a relatively good efficacy, especially for those who received first-line pyrotinib treatment and those who were sensitive to previous trastuzumab treatment. Patients with brain metastasis and liver metastases also benefit from pyrotinib treatment, especially for patients treated with brain radiotherapy and/or surgery. ECOG, HER2 status, brain metastasis, liver metastasis, number of pyrotinib treatment lines, previous lapatinib treatment, combined capecitabine therapy and trastuzumab resistance were independent prognostic factors for PFS in HER2 Positive MBC patients treated with pyrotinib. The most common adverse reaction associated with pyrotinib is diarrhea, which can be well controlled through antidiarrheal treatment. Pyrotinib combined with vinorelbine has similar efficacy to pyrotinib combined with capecitabine and has fewer side effects, and can be used as an alternative to capecitabine.