Comparative analysis of EpCAM high-expressing and low-expressing circulating tumour cells with regard to their clonal relationship and clinical value
Menée à partir de l'analyse de l'ADN de cellules tumorales circulantes (CTCs) issues de patientes atteintes d'un cancer métastatique du sein, cette étude examine, en fonction du niveau d'expression de la molécule d'adhésion EpCAM, les caractéristiques clonales (présence d'aberrations chromosomiques et de mutations) et la valeur prédictive des CTCs
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.
British Journal of Cancer , article en libre accès, 2023