Detection of discordant HER2 status by FISH in circulating tumor cells and disseminated tumor cells in early-stage breast cancer using a microfluidic-based cell enrichment and extraction platform (OncoCEE).

TPS10631 Background: Evaluation of HER2 in circulating (CTCs) and disseminated (DTC) tumor cells may aid therapy in breast cancer. We report here the discordance in HER2 status in CTCs and DTCs in early stage breast cancer by fluorescence in situ hybridization (FISH) using a microfluidic cell platform (OncoCEE). Methods: Blood (10ml) and BM (1-2ml) from patients with Stage T1 and T2 breast cancer was collected in OncoCEE-Sure collection tubes. Mononuclear cells were recovered using a Percoll density gradient method, incubated with a mixture of 10 primary capture antibodies (Abs), and introduced into streptavidin coated OncoCEE microchannels for tumor cell capture. For blood samples, captured cells were stained with anti cytokeratin (CK) and CD45 Abs for CTC enumeration followed by FISH using probes specific to centromere 17 and HER2. For BM samples, captured cells were subjected to HER2 FISH analysis. The ratio of HER2:CEP17>2.0 in any CK+/ CD45- and CK-/CD45- cell was regarded as positive for HER2. Resul...