Genome-wide copy number analysis of circulating tumor cells from patients (pts) with metastatic breast cancer (MBC).

9 Background: We developed a novel approach to isolate circulating tumor cells (CTCs) via immunomagnetic enrichment followed by fluorescence activated cell sorting (IE/FACS) and examined copy number alterations in these cells. Methods: Magnetic beads coated with EpCAM mAb were added to blood to enrich for tumor cells. Enriched samples were then subjected to FACS analysis using differentially labeled mAbs to distinguish tumor cells (EpCAM+) from leukocytes (CD45+) during sorting. DNA from isolated tumor cells was subjected to whole genome amplification (WGA) and copy number analysis via array comparative genomic hybridization (aCGH). The assay was evaluated in CTCs from 5 MBC pts with matched archival primary tumors and later extended to an additional 176 MBC pts, 97 of which were successfully profiled. Results: Comparison of CTCs with matched archival primary tumors confirmed shared lineage with notable divergence. In addition, serial testing of CTCs confirmed reproducibility, and indicated genomic change...