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 over time. Genomic profiling of CTCs from 102 MBC pts revealed a wide range of copy number alterations including those previously reported in breast cancer. Comparison with a published aCGH dataset of primary breast tumors revealed similar frequencies of recurrent genomic copy number aberrations. Conclusions: It is feasible to isolate CTCs away from hematopoietic cells with high purity via IE/FACS and profile them via aCGH analysis following WGA. Our approach may be utilized to explore genomic events involved in cancer progression and to monitor therapeutic efficacy of targeted therapies in clinical trials in a relatively non-invasive manner. This work was supported by grants from the CALGB, BCRF, TBCRC (Avon, Komen), EDRN and U54.
Genome-wide copy number analysis of cerebrospinal fluid tumor cells and their corresponding archival primary tumors
