Galatea Kallergi
University of Crete, Greece
Title: Isolation and characterization of circulating tumor cells (CTCs) in triple negative breast cancer patients in response to chemotherapy
Biography
Biography: Galatea Kallergi
Abstract
Circulating tumor cells are considered as a liquid real time biopsy. Their phenotype is not always in concordance with the primary tumor due to cancer evolution. Therefore their characterization is critical before and after therapy in order to determine the response to therapy. Our results on CTCs have shown that CTCs phenotype can change in response to standard chemotherapy. Particularly blood samples from 55 early Triple negative breast cancer patients (TNBC) was examined before and after adjuvant chemotherapy. The expression of Cytokeratins (CK), Estrogen Receptor (ER), Progesterone Receptor (PR), EGFR and HER2 on CTCs was assessed using double immunofluorescent experiments and ARIOL analysis. Our results revealed that CTCs were detected in 39 out of 55 (70.9%) patients with early TNBC tumors before the initiation and in 34 out of 55 (61.8%) after the completion of adjuvant chemotherapy. The frequency of ER-, PR- and HER2- expressing CTCs was significantly reduced post-chemotherapy (p=0.019, p=0.017, 0.018) while the frequency of EGFR was not altered. The percentage of ER-, PR-, HER2- and EGFR-expressing CTCs in metastatic TNBC patients was 26%, 34%, 57% and 62%, respectively. Triple staining experiments revealed that there was no co-expression of CK/EGFR/ER, CK/EGFR/PR or CK/PR/HER2 in CTCs suggesting that ER, PR and EGFR were expressed in different subclones of CTCs in TNBC patients. In conclusion a significant percentage of CTCs in TNBC patients express HER2 and EGFR before treatment, implying that these receptors could be a potential target for the limitation of metastasis. EGFR-expressing CTCs persist after adjuvant chemotherapy, suggesting that additional treatment with EGFR-targeting agents could be used post-chemotherapy to eliminate chemo-resistant CTCs.