Minimal residual disease and circulating tumor cells in breast cancer

Breast Cancer Research, Oct 2011

Tumor cell dissemination in bone marrow or other organs is thought to represent an important step in the metastatic process. The detection of bone marrow disseminated tumor cells is associated with worse outcome in early breast cancer. Moreover, the detection of peripheral blood circulating tumor cells is an adverse prognostic factor in metastatic breast cancer, and emerging data suggest that this is also true for early disease. Beyond enumeration, the characterization of these cells has the potential to improve risk assessment, treatment selection and monitoring, and the development of novel therapeutic agents, and to advance our understanding of the biology of metastasis.

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Minimal residual disease and circulating tumor cells in breast cancer

Michail Ignatiadis 0 Monica Reinholz 1 0 Medical Oncology Department and Breast Cancer Translational Research Laboratory, Institut Jules Bordet , 121 Boulevard de Waterloo, 1000 Brussels , Belgium 1 Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, MN 55905 , USA Tumor cell dissemination in bone marrow or other organs is thought to represent an important step in the metastatic process. The detection of bone marrow disseminated tumor cells is associated with worse outcome in early breast cancer. Moreover, the detection of peripheral blood circulating tumor cells is an adverse prognostic factor in metastatic breast cancer, and emerging data suggest that this is also true for early disease. Beyond enumeration, the characterization of these cells has the potential to improve risk assessment, treatment selection and monitoring, and the development of novel therapeutic agents, and to advance our understanding of the biology of metastasis. - Introduction Breast cancer (BC) is the most common cancer in women in Europe [1]. Despite surgery and adjuvant systemic therapy, many women with early BC still relapse and die of their disease. Minimal residual disease (MRD) after potentially curative surgery for BC is thought to contribute to disease relapse and to be the target of adjuvant treatment. MRD is defined as micrometastatic cells undetectable by conventional imaging and laboratory tests. Surrogates of MRD are tumor cells detected in the bone marrow (disseminated tumor cells (DTCs)) and peripheral blood (circulating tumor cells (CTCs)) [2]. The detection and characterization of DTCs/CTCs are expected to lead to personalized treatment strategies and accelerate the development of novel therapeutic agents for BC [2]. Furthermore, genotypic and phenotypic characterization of DTCs/CTCs at the single cell level Antibody-based assays Since there are no universal tumor-specific antigen/ genes, epithelial-specific antigens, including cytokeratins (CKs), epithelial cell adhesion molecule (EpCAM), and growth factor receptors (for example, human epidermal growth factor receptor (HER2)), have been used as markers of choice for the detection of DTCs/CTCs. In consensus meetings, the use of appropriate staining controls, directly labeled fluorescent monoclonal antibodies, identification of DTCs/CTCs based on cytomorphologic criteria/phenotypic features, and validation by two independent observers have been suggested as measures to reduce false-positive results [8,9]. CellSearch (Veridex, Warren, NJ, USA) is an automated enrichment and immunostaining system for CTC FDA approval Reference Microfluidics. Enrichment based on physical properties Depletion of CD45+ cells Microfluidics. EpCAM-coated microposts RBC lysis, CK+, EpCAM+ enrichment Fiber-optic array scanning technology (FAST) Collagen adhesion matrix (CAM) assay Invasion and digestion of cell adhesion Single gene or multi-marker RT-PCR assays Multiparameter flow cytometry MUC1+ and EpCAM+ enrichment Ficoll or EpCAM+ enrichment or depletion of CD45+ cells HER2, MUC1 and EpCAM CK19, MGB1, HER2, MUC1 mRNA EpCAM+/CK8, 18, 19+/CD45CK, cytokeratin; EpCAM, epithelial cell adhesion molecule; FDA, Food and Drug Administration; HER, human epidermal growth factor receptor; MGB1, mammaglobin-A; MUC1, mucin 1; RBC, red blood cell. aApproval as an aid in monitoring patients with metastatic breast, colorectal and prostate cancer. detection that uses microscopic ferrofluids coated with an antibody against EpCAM to magnetically separate epithelial cells from whole blood [10]. Captured cells are stained with antibodies specific for cytokeratins 8, 18 and 19 (pan-CK) and CD45 (specific for leucocytes) and stained with 46-diamidino-2-phenylindole-2 (DAPI; to confirm the presence of a cell nucleus). A CTC is defined as a cell staining for pan-CK and DAPI, but not for CD45. Currently, CellSearch is the only technology that has received US Food and Drug Administration (FDA) approval for CTC detection as an aid in monitoring patients with metastatic breast, colorectal and prostate cancer [10-12]. The performance of CellSearch for CTC detection in metastatic solid tumors has also been validated in ring studies [13,14]. Other technologies include the MagSweeper, which uses immunomagnetic separation and gently enriches target cells by 108-fold from blood, eliminating cells that are not bound to magnetic particles [6]. This process has been shown to keep cell function intact and not to perturb rare cell gene expression [6]. CTCs have been also detected using multi-parameter flow cytometry, and their detection with this technology was associated with poor outcome in women with BC [15]. MAINTRAC, another method, detects circulating epithelial tumor cells from whole unseparated blood, and uses a laser scanning cytometer after staining with anti-human epithelial and anti-CD45 fluorescent antibodies [16]. This technology results in CTC counts up to 105 per milliliter of blood (...truncated)


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Michail Ignatiadis, Monica Reinholz. Minimal residual disease and circulating tumor cells in breast cancer, Breast Cancer Research, 2011, pp. 222, 13, DOI: 10.1186/bcr2906