[PTEN loss correlates withthe clinical efficacy of lapatinib in HER2 positive metastatic breast cancer with trastuzumab-resistance].

To discuss the indexes related to the efficacy of lapatinib after failure in trastuzumab in HER2-positive metastatic breast cancer (MBC) such as the status of PTEN, p-4EBP1 and clinical features.Sixtymatched patients were included. Immunohistochemical (IHC) test of tissue specimens of metastatic lesions were applied to determine the status of PTEN and p-4EBP1. The correlation betweenclinical efficacy andthestatus of PTEN, p-4EBP1 and clinical features were analysed by long-rank test and Cox regression.In all patients, themedian progression free survival (PFS), ORR and CBR was 4.6 months, 36.7% and 50.0% respectively.Univariate analysis revealed that lapatinib-treated patients with PTEN loss (P = 0.015) and liver metastasis (P = 0.02) had significantly shorter median PFS. Multivariate analysis revealed that patients with PTEN lossandliver metastasis had higher risk of diseaseprogression (P = 0.005, 0.006, respectively).HER2-positive MBC with trastuzumab-resistance could benefit from lapatinib regimen. PTEN statusand liver metastasis couldpredict theclinical efficacyof subsequent lapatinib therapy. The detection ofrelated biomarkers could provide some referenceto optimize the personal treatment with HER2-positive breast cancer.