Multiple biomarker expression in circulating tumor cells (CTCs) from locally advanced/inflammatory (LA/IBC) and metastatic breast cancer (MBC) patients (pts)

Abstract

1092 Background: Numeration of CTCs from MBC pts is predictive of outcome. Quantitative changes in CTC-s are currently tested for their potential to monitor therapy (Rx). Biomarker characterization of CTCs may be a useful adjunctive guide for Rx selection. Methods: At the COHCC between May 1, 2008 and December 31, 2008, consecutively treated pts with LABC/IBC, or with newly diagnosed/progressing MBC were accrued. Blood samples (20–30 mL) were procured prior to initiating neoadjuvant (neo)Rx (LABC and IBC patients) or systemic Rx (MBC), and were sent to PARC for analysis. A novel high-speed scanning instrument located CTCs from cytokeratin (CK) labeling enabling high resolution images to be selectively acquired using digital microscopy. From these images, CTCs were identified by CK, DAPI (nuclear marker) and CD45, and protein expression levels were determined for HER-2, estrogen receptor (ER), Excision repair cross-complementation group 1 (ERCC1), and EGFR. Cell lines with expression of each marker were used for normalization of the cell intensities, and a scoring system was used to account for relative number and expression levels of markers on the CTCs. Results: Twenty-seven pts with LABC, 4 pts with IBC, and 11 pts with MBC were enrolled. We have observed CTCs prior to initiating neoRx in all pts with IBC relative to 39% of all LABC/IBC cases, and in 57% of pts (n:14) with HER-2+ primary BC versus 24% (n = 17) with HER-2- BC . ER status, size, or grade did not predict for CTC detection. Numeration of CTCs was seen in 45% of pts with MBC. Expression of EGFR and ERCC1 was detected in 3 of 4, and 2 of 4 tested CTC samples from MBC cases. Expression of HER-2 and ER was observed on 1 of 3 and 3 of 4 CTC samples; there was discrepancy between the CTC expression profile and HER-2 and ER status of the primary BC in one case each. Conclusions: Detecting multiple markers in CTCs from pts with MBC is feasible, and similar testing in LABC/IBC patients is needed. Such multiplex testing may allow for more personalized Rx for pts with LABC/IBC and MBC. No significant financial relationships to disclose.