Effect of afatinib alone and in combination with dasatinib in triple-negative breast cancer cell lines.

1128 Background: TNBC is a subtype of breast cancer negative for expression of estrogen and progesterone receptors and lack of HER2 gene amplification. It is associated with poor prognosis and lack of targeted therapies. Therefore, there is a need for identification of new therapies. EGFR, a member of the ErbB family, is frequently overexpressed in TNBC. Furthermore, crosstalk between EGFR and Src kinase signaling has been observed in breast cancer. The aim of this study is to assess the activity of afatinib, an irreversible pan-HER tyrosine kinase inhibitor alone and in combination with dasatinib, a Src inhibitor, in TNBC. Methods: Using proliferation assays, the effect of afatinib was assessed alone and in combination with dasatinib in TNBC cell lines. Combination indexes (CI) at ED50, effective dose of combination that inhibits 50% of growth, were determined using the Chou and Talalay equation. CI 1 implies antagonism. Results: The 6 TNBC cell lines tested responded to afat...