RNA-Based CTC Analysis Provides Prognostic Information in Metastatic Breast Cancer

In metastatic breast cancer (MBC) the molecular characterization of circulating tumor cells (CTCs) provides a unique tool to understand metastasis-biology and therapy-resistance. We evaluated the prognostic significance of gene expression in EpCAM((+)) CTCs in 46 MBC patients based on a long follow-up. We selected a panel consisting of stem cell markers (CD24, CD44, ALDH1), the mesenchymal marker TWIST1, receptors (ESR1, PGR, HER2, EGFR) and the epithelial marker CK-19. Singleplex RT-qPCR was used for TWIST1 and CK-19 and multiplex RT-qPCR for stem cell markers and receptors. A group of 19 healthy donors (HD) was used as control. Univariate (p = 0.001) and multivariate analysis (p = 0.002) revealed the prognostic value of combined gene expression of CK-19(+), CD44(high)/CD24(low), ALDH1(high)/CD24(low) and HER2 over-expression for overall survival (OS). The Kaplan-Meier estimates of OS were significantly different in patients positive for CK-19 (p = 0.028), CD44(high)/CD24(low) (p = 0.002), ALDH1(high)/CD24(low) (p = 0.007) and HER2-positive (p = 0.022). Our results indicate that combined gene expression analysis in EpCAM((+)) CTCs provides prognostic information in MBC.

Automated summary

This study evaluated the prognostic significance of gene expression in CTCs of 46 MBC patients, showing that combined gene expression analysis can provide prognostic information for MBC.