Real-World Outcome and Prognostic Factors Among HER2-Positive Metastatic Breast Cancer Patients Receiving...

Area of Science:

• Oncology
• Pharmacology
• Clinical Medicine

Background:

• Human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) remains a significant clinical challenge.
• Pyrotinib is a targeted therapy agent used in HER2-positive cancers.

Purpose of the Study:

• To evaluate the real-world efficacy and safety of pyrotinib-based therapy in HER2-positive MBC.
• To identify factors influencing treatment response and outcomes.

Main Methods:

• Retrospective analysis of 169 HER2-positive MBC patients treated with pyrotinib-based regimens from September 2018 to February 2022.
• Assessment of objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and adverse events (AEs).
• Exploration of baseline serum vascular endothelial growth factor-A (VEGF-A) as a predictive factor.

Main Results:

• The overall cohort achieved an ORR of 65.1%, DCR of 87.6%, and median PFS (mPFS) of 12.4 months.
• Pyrotinib demonstrated efficacy across different treatment lines, with mPFS of 16.5 months in the first-line setting.
• Diarrhea was the most common AE (88.2%); severe diarrhea correlated with shorter mPFS (6.9 months vs 13.3 months).
• Low baseline VEGF-A was associated with higher ORR (81.5% vs 43.5%) and longer mPFS (19.1 months vs 7.8 months).
• Diarrhea severity and baseline VEGF-A were independent prognostic factors for PFS.

Conclusions:

• Pyrotinib-based regimens offer promising efficacy and manageable safety in HER2-positive MBC.
• Severe diarrhea and elevated baseline VEGF-A are predictive of poorer treatment outcomes.
• These findings support the use of pyrotinib and highlight key biomarkers for patient selection and outcome prediction.