Comparative analysis of EpCAM high-expressing and low-expressing circulating tumour cells with regard to their clonal relationship and clinical value

Abstract

Background Circulating tumour cells (CTCs) are mainly enriched based on the epithelial cell adhesion molecule (EpCAM). Although it was shown that an EpCAM low-expressing CTC fraction is not captured by such approaches, knowledge about its prognostic and predictive relevance and its relation to EpCAM-positive CTCs is lacking. Methods We developed an immunomagnetic assay to enrich CTCs from metastatic breast cancer patients EpCAM independently using antibodies against Trop-2 and CD-49f and characterised their EpCAM expression. DNA of single EpCAM high expressing and low expressing CTCs was analyzed regarding chromosomal aberrations and predictive mutations. Additionally, we compared CTC-enrichment on the CellSearch system using this antibody mix and the EpCAM based enrichment. Results Both antibodies acted synergistically in capturing CTCs. Patients with EpCAM high-expressing CTCs had a worse overall and progression-free survival. EpCAM high- and low-expressing CTCs presented similar chromosomal aberrations and mutations indicating a close evolutionary relationship. A sequential enrichment of CTCs from the EpCAM-depleted fraction yielded a population of CTCs not captured EpCAM dependently but harbouring predictive information. Conclusions Our data indicate that EpCAM low-expressing CTCs could be used as a valuable tumour surrogate material—although they may be prognostically less relevant than EpCAM high-expressing CTCs—and have particular benefit if no CTCs are detected using EpCAM-dependent technologies.

ZeptoCTC - Sensitive Protein Analysis of True Single Cell Lysates using Reverse Phase Protein Arrays (RPPA)

“…Due to this precise performance of ZeptoCTC, we argue that the observed signal variabilities observed between single cells – also of the same cell line – are pointing toward well-known cell-to-cell heterogeneity, a phenomenon that has been previously noted in other single cell experiments (43–45). For instance, EpCAM expression levels in two MCF7 cells were highly different, matching observations we have made previously suggesting a continuum of EpCAM-positivity in MCF-7 cells (46). Similarly, varying levels of Akt and pAkt in single MCF7 cells treated with Capivasertib suggest diverse drug responses within individual cells.…”

Transcriptome Profiling of Circulating Tumor Cells to Predict Clinical Outcomes in Metastatic Castration-Resistant Prostate Cancer

“…Genes were ranked using HR (Figure S5). Notably, the epithelial marker, EPCAM, was not a high-ranking prognosticator in this cohort, yet CTCs expressing EPCAM are known to be prognostically relevant in various malignancies [7,19]. Instead, genes involved in AR signaling (KLK3, HOXB13, and GRHL2), and metastasis (MYO6 and TRPM8) were more informative [20,21].…”

Sensitive Detection of Tumor Cells Using Protein Nanoparticles with Multiple Displays of DNA Aptamers and Bioluminescent Reporters

“…Therefore, the protein nanoparticles would tolerantly select for antigens and specific DNA aptamers that target tumor cells. In fact, the antigenic complexity and heterogeneity of CTCs lead to poor detection and capture of CTCs by a specific antibody, such as EpCAM. − Protein nanoparticles have a potential for detecting a variety of CTCs with different phenotypes.…”