Role of HER3 expression and PTEN loss in patients with HER2-overexpressing metastatic breast cancer (MBC) who received taxane plus trastuzumab treatment

Abstract

Background:The aim of this study was to investigate the role of human epidermal growth factor receptor (HER3) and PTEN expression in patients with HER2-overexpressing metastatic breast cancer (MBC).Methods:One hundred twenty-five MBC patients who were treated with taxane plus trastuzumab chemotherapy as first-line therapy were included in this analysis. Immunohistochemical (IHC) staining with HER3 and PTEN antibodies were conducted retrospectively.Results:Patients who had negative HER3 staining (62.4%) had a better progression-free survival (PFS) than did those who had positive HER3 staining (P=0.001; median PFS, 21 vs 11 months). Patients who had a PTEN score >20 (78.1%) showed longer PFS than did those with a PTEN score ⩽20 (P=0.006; median PFS, 13 vs 9 months). Patients who had a PTEN score >20 exhibited a longer overall survival (OS) than did those with a PTEN score ⩽20 (P=0.005; median OS, 48 vs 25 months). HER3 negativity and PTEN loss were identified as independent risk factors for PFS. PTEN loss was identified as an independent risk factor for OS.Conclusion:HER3 and PTEN expressions may be predictive markers, and PTEN expression may be a predictive and prognostic biomarker for trastuzumab treatment in HER2-positive MBCs.