Abstract P3-03-01: Minimal Residual Disease Monitoring in Breast Cancer Patients

Abstract

Abstract BACKGROUND: Breast cancer (BC) patients still harbor a considerable risk of metastatic relapse caused by minimal residual disease (MRD) despite of complete removal of primary tumor. The aim of this study was to identify single disseminated tumor cells (DTC) in the bone marrow and circulating tumor cells (CTC) in the peripheral blood as potential biomarkers for therapy response monitoring and metastatic relapse risk prediction. Finally, the gene expression profiles of CTCs have been analyzed. METHODS: A total of 87 patients with diagnosed BC at stage I to III and 115 metastatic patients were enrolled into a prospective study between years 2008 - 2010. Peripheral blood (5ml) for CTC-detection was collected from primary BC patients before chemotherapy (CHT), after 2 cycles of CHT and after the CHT. Metastatic BC patients have been examined for CTCs before starting a new line of the treatment. Bone marrow aspirates from 16 premenopausal BC patients (mean age 31) with primary tumor were analyzed for the presence of DTC by immunocytochemistry using the pan-cytokeratin antibody A45-B/B3 (Epimet™, AS Diagnostik, Germany) before surgery. CTC detection in blood was performed by AdnaTest BreastCancerTM(AdnaGen AG, Germany), which is based on the detection of EpCAM, HER2 and MUC1 specific transcripts in enriched CTC-lysates. cDNA from isolated CTCs has been further pre-amplified and used for multimarker qPCR gene expression profiling using Biomark® microfluidic 48x48 GE Dynamic arrays (Fluidigm, USA). qPCR results have been analyzed by GENEX vs. 5.2 software (MultiD Analysis). RESULTS: 286 CTC samples have been analyzed in total. The analysis has shown that the expression profiles of CTCs from primary BC patients have been significantly different comparing them to the CTC-profiles from metastatic BC patients for several of tested genes (e.g., CK19, GA7332, MLFIP1, SATB1, PTEN). Interestingly, before surgery of primary tumor DTCs were found in 5/16 patients (31 %) and CTCs in 7/16 (43 %). Both DTCs and CTCs together were found in 4/16 (25%) patients. In 18% of the primary BC patients no dissemination markers were found CONCLUSIONS: Information based on the CTCs-gene expression profiles could provide an additional support for therapy management. Metastatic potential of enriched CTCs will be further evaluated on the single cell level. This work has been supported by Grant Agency of Ministry of Health, Czech Republic (IGA NS9976) and Grant Agency of Charles University in Prague, Czech Republic no. 7709 and 59410. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-03-01.