title: Establishment of a multimarker qPCR panel for the molecular characterization of circulating tumor cells in blood samples of metastatic breast cancer patients during the course of palliative treatment.
abstract: BACKGROUND
  Circulating tumor cells (CTC) are discussed to be an ideal surrogate marker for individualized treatment in metastatic breast cancer (MBC) since metastatic tissue is often difficult to obtain for repeated analysis. We established a nine gene qPCR panel to characterize the heterogeneous CTC population in MBC patients including epithelial CTC, their receptors (EPCAM, ERBB2, ERBB3, EGFR) CTC in Epithelial-Mesenchymal-Transition [(EMT); PIK3CA, AKT2), stem cell-like CTC (ALDH1) as well as resistant CTC (ERCC1, AURKA] to identify individual therapeutic targets.
  
  
  RESULTS
  At TP0, at least one marker was detected in 84%, at TP1 in 74% and at TP2 in 79% of the patients, respectively. The expression of ERBB2, ERBB3 and ERCC1 alone or in combination with AURKA was significantly associated with therapy failure. ERBB2 + CTC were only detected in patients not receiving ERBB2 targeted therapies which correlated with no response. Furthermore, patients responding at TP2 had a significantly prolonged overall-survival than patients never responding (p = 0.0090).
  
  
  METHODS
  2 × 5 ml blood of 62 MBC patients was collected at the time of disease progression (TP0) and at two clinical staging time points (TP1 and TP2) after 8-12 weeks of chemo-, hormone or antibody therapy for the detection of CTC (AdnaTest EMT-2/StemCell Select™, QIAGEN Hannover GmbH, Germany). After pre-amplification, multiplex qPCR was performed. Establishment was performed using various cancer cell lines. PTPRC (Protein tyrosine phosphatase receptor type C) and GAPDH served as controls.
  
  
  CONCLUSIONS
  Monitoring MBC patients using a multimarker qPCR panel for the characterization of CTC might help to treat patients accordingly in the future.
authors.affiliation: Department of Gynecology and Obstetrics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Maren
authors.initials: M
authors.lastname: Bredemeier
authors.affiliation: Department of Gynecology and Obstetrics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Philippos
authors.initials: P
authors.lastname: Edimiris
authors.affiliation: Department of Medical Oncology, West German Cancer Center, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Mitra
authors.initials: M
authors.lastname: Tewes
authors.affiliation: Department of Gynecology and Obstetrics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Pawel
authors.initials: P
authors.lastname: Mach
authors.affiliation: Department of Gynecology and Obstetrics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Bahriye
authors.initials: B
authors.lastname: Aktas
authors.affiliation: QIAGEN Hannover GmbH, Langenhagen, Germany.
authors.forename: Doreen
authors.initials: D
authors.lastname: Schellbach
authors.affiliation: QIAGEN Hannover GmbH, Langenhagen, Germany.
authors.forename: Jenny
authors.initials: J
authors.lastname: Wagner
authors.affiliation: Department of Gynecology and Obstetrics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Kimmig
authors.affiliation: Department of Gynecology and Obstetrics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Kasimir-Bauer
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics*; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D061986:MCF-7 Cells; D008991:Monitoring, Physiologic / Q000379:methods; D009362:Neoplasm Metastasis; D009360:Neoplastic Cells, Circulating / Q000378:metabolism* / Q000473:pathology; D010166:Palliative Care; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D059467:Transcriptome; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor
keywords: circulating tumor cells; metastatic breast cancer; multimarker gene panel