Discordance in HER2 gene amplification in circulating and disseminated tumor cells in patients with operable breast cancer

Abstract

Human epidermal growth factor receptor 2 (HER2) gene amplification in circulating tumor cells (CTCs) and disseminated tumor cells (DTCs) might be useful for modifying Herceptin therapy in breast cancer. In the process of investigating the utility of a microfluidic platform for detecting HER2 gene amplification in these cells, we observed novel results on discordance of HER2 status. Peripheral blood (8.5 mL) and bone marrow (BM) (7.5–10 mL) were collected prospectively from patients with clinical stages I–IV breast cancer. Mononuclear cells were recovered, stained with cytokeratin (CK), CD45, and DAPI, and processed through microfluidic channels for fluorescence in situ hybridization (FISH). A ratio of HER2:CEP17 >2 in any CK+/CD45 or CK−/CD45 cell was regarded as positive for HER2 gene amplification. Peripheral blood from 95 patients and BM from 78 patients were studied. We found CK+/CD45−/DAPI+ CTCs in 27.3% of patients. We evaluated HER2 gene amplification by FISH in 88 blood and 78 BM specimens and found HER2+ CTCs in 1 of 9 (11.1%) and HER2+ DTCs (27.2%) in 3 of 11 patients with HER2+ primary tumor. Among patients with a HER2− primary tumor, 5 of 79 had HER2+ CTCs (6.3%) and 14 of 67 had HER2+ DTCs (20.8%). The overall rate of discordance in HER2 status was 15% between primary tumor and CTCs and 28.2% between primary tumor and DTCs. HER2 was amplified in CTCs and DTCs in a portion of both HER2+ and HER2− primary tumors. HER2 discordance was more frequent for DTCs. The clinical implications of evaluating HER2 status in CTCs and DTCs in breast cancer needs to be established in prospective clinical trials. The cell enrichment and extraction microfluidic technology provides a sensitive platform for evaluation of HER2 gene amplification in CTCs and DTCs.

Prognostic Value of Circulating Tumor Cells Identified Before Surgical Resection in Nonmetastatic Breast Cancer Patients

“…Characterization of CTCs is important since it has been shown that therapeutic targets such as HER2neu may be found on CTCs, even when the primary tumor is HER2 negative. (37) Such findings would have clear significance for future clinical trials designed at targeted eradication of CTCs. The concept of “liquid biopsy”, including gene mutation analysis in cell-free DNA, holds promise of providing real-time snapshots of the microscopic tumor burden throughout treatment.…”

Circulating tumor cells in breast cancer

“…As any other tumor material (surgical specimen, biopsy, fine needle aspirate. ), CTC can be characterized with "omics" analyses: genomics, either focused on copy-number profiles (Kanwar et al, 2015;Neves et al, 2014;Polzer et al, 2014), ERBB2 amplification (Krishnamurthy et al, 2013;Mayer et al, 2011), point mutations (Deng et al, 2014;Fernandez et al, 2014;Markou et al, 2014;Pestrin et al, 2015;Schneck et al, 2013) or on DNA methylation (Chimonidou et al, 2013a(Chimonidou et al, , 2013b(Chimonidou et al, , 2011, transcriptomics (Mostert et al, 2015;Onstenk et al, 2015b;Powell et al, 2012;Sieuwerts et al, 2011) and proteomics. Among proteins of potential therapeutic interest, the estrogen and progesterone receptors (Nadal et al, 2012;Somlo et al, 2011), HER2 (Ligthart et al, 2013), Ki67 (Paoletti et al, 2015) and apoptosis and DNA-repair related proteins (Garcia-Villa et al, 2012;Smerage et al, 2013) have been investigated, together with PDL1 expression on CTC (Mazel et al, 2015) and many other potential biomarkers.…”

Circulating Tumor Cells: A Multifunctional Biomarker

“…1). Microfluidic platforms (CTC-chips) are based on devices with antibodycoated microstructures, which allow the mixing of blood cells through the generation of microvortices to significantly enhance the number of interactions between target CTCs and the antibody-coated chip surface (14)(15)(16). Such an approach enables the capture of large numbers of viable CTCs in a single step from whole blood without the need for an initial enrichment step.…”