Circulating Tumor Cells: A Review of Non–EpCAM-Based Approaches for Cell Enrichment and Isolation

Abstract

International audienceBackground: Circulating tumor cells (CTCs) are biomarkers for non-invasively measuring the evolution of tumor genotypes during treatment and disease progression. Recent technical progress has made it possible to detect and characterize CTCs at the single-cell level in blood. Content: Most current methods are based on epithelial cell adhesion molecule (EpCAM) detection, but numerous studies have demonstrated that EpCAM is not a universal marker for CTC detection since it fails to detect both carcinoma cells that undergo epithelial-mesenchymal transition (EMT), and CTCs of mesenchymal origin. Moreover, EpCAM expression has been found in patients with benign diseases. A large proportion of the current studies and reviews about CTCs describe EpCAM based methods, but there are evidences that not all tumor cells can be detected using this marker. Here we describe the most recent EpCAM-independent methods for enriching, isolating and characterizing CTCs, based on physical and biological characteristics, and point out their main advantages and disadvantages.Summary: CTCs offer an opportunity to obtain key biological information required for the development of personalized medicine. However there is no universal marker of these cells. To strengthen the clinical utility of CTCs, it is important to improve existing technologies and develop new, non-EpCAM based systems to enrich and isolate CTCs

Circulating tumor cells in breast cancer

“…Examples of commercial tests based on negative depletionRosetteSep. [11] Finally, CTC detection and characterization can be done by immunocytological (flow cytometry); molecular (reverse transcription-polymerase chain reaction [RT-PCR]); and functional assays (cell culture -EPISPOT; xenotransplantation).…”

Circulating Tumor Cells in the Parallel Invasion Model Supporting Early Metastasis

“…Alternative marker-independent methods are based on physical properties of CTCs for discrimination from blood cells such as size, rigidity, surface charge, flow characteristics and others. [19] These techniques result in detection of larger numbers of CTCs compared to the CellSearch© system and the additional cells found may be more aggressive and invasive than EpCAM-positive cancer cells. The multitude of methods to capture CTCs are described in a large number of comprehensive reviews.…”

Sample types applied for molecular diagnosis of therapeutic management of advanced non-small cell lung cancer in the precision medicine

“…size, density and electric charge) or biological (e.g. surface protein expression and invasive capacity) properties have been developed [70]. The only system approved by the United States Food and Drug Administration (US FDA) for enrichment and enumeration of CTCs is the CellSearch ® system, which enriches isolated CTCs by using magnetic bead-conjugated antibodies against epithelial-cell adhesion molecules (EpCAM) in 7.5 mL of blood [70].…”

“…surface protein expression and invasive capacity) properties have been developed [70]. The only system approved by the United States Food and Drug Administration (US FDA) for enrichment and enumeration of CTCs is the CellSearch ® system, which enriches isolated CTCs by using magnetic bead-conjugated antibodies against epithelial-cell adhesion molecules (EpCAM) in 7.5 mL of blood [70]. However, a large body of evidence has demonstrated that EpCAMs is not universal makers for isolating CTCs, especially for those CTCs that have undergone epithelial-mesenchymal transition or have originated from the mesenchymal [70].…”