(804c) Simultaneous, m-RNA and/Or Micro-RNA, and Protein Expression On Individual, Circulating Tumor Cells

Human Epidermal Growth Factor Receptor family includes four members: EGFR/HER1, ErbB2/HER2, HER3, and HER4. This signaling cascade has important prognostic and predictive significance in a variety of solid tumors and has several targeted therapies that are currently approved or in development.  EGFR and Her 2 currently have approved therapeutic that can block such pathways. Therefore, characterization of CTCs for presences of these drugable targets is of significant clinical interest since CTCs may give the most dynamic snapshot of the state of tumor progression.

Since it is challenging to obtain serial metastatic site biopsies, a significant promise of CTCs is in utilizing them as liquid biopsies and evaluate them for various targets including the Her family. A significant challenge in using CTCs as predictive markers is that more than a third of patients with metastatic disease do not have detectable CTCs by EpCAM-based technology.  One hypothesis is that these patients are more likely to have CTCs not captured by EpCAM based positive enrichment, such as those that have undergone epithelial to mesenchymal transition, EMT, which down regulates epithelial markers, such as EpCAM. EMT-like characteristics of CTCs has been reported recently by several groups.

As opposed to using positive EpCAM selection we are using a negative enrichment system, we have identified CTCs in all breast cancer stages.  However, to further characterize these cells, we need more than the traditional four color epi-flourescent and confocal approaches. In this presentation, we will demonstrated how we are able to obtain 6, and possibly more, specifically targeted cell markers, including mRNA, microRNA, as well as cellular proteins on each cell.  Markers targeted include: cytokeratin proteins, vimentin proteins, HER and EGRF surface proteins, and messenger RNA, and microRNA for HER, EGFR, and other relevant markers.  In addition, we will present the potential to quantify this presence of these targets using spectral deconvolution technology.