title: Circulating tumor cells (CTCs) in metastatic breast cancer (MBC): prognosis, drug resistance and phenotypic characterization.
abstract: BACKGROUND
  the expression of ATP-binding cassette transporters on circulating tumor cells (CTCs) is predictive of response to chemotherapy in cancer patients. We tested the hypothesis that drug-resistant CTCs might have predictive value in metastatic breast cancer (MBC) and possibly retain stem-like properties.
  
  
  METHODS
  CTCs obtained from 42 MBC patients were evaluated for multidrug-resistance-related proteins (MRPs), aldehyde dehydrogenase 1 (ALDH1), estrogen receptor α (ERα) and human epidermal growth factor receptor 2 (HER2/neu). Primary objective was to evaluate the prognostic and predictive value of CTCs profile. Secondary end points were the level of concordance in ERα and HER2/neu status between primary tumors and CTCs and the correlation in CTCs between ALDH1, drug resistance profile and number of MRPs.
  
  
  RESULTS
  A difference in progression-free survival (PFS) was found between CTCs-positive and CTCs-negative patients. PFS was shorter in patients with a 'drug resistance' CTCs profile and in patients whose CTCs expressed two or more MRPs. No correlation was found between tumor characteristics and ALDH1. ALDH1 correlated to negative ERα and positive HER2/neu status in CTCs. The correlation between the number of MRPs expressed in CTCs and ALDH1 was statistically significant.
  
  
  CONCLUSIONS
  in MBC, the presence of CTCs expressing MRPs and ALDH1 is predictive of response to chemotherapy.
authors.affiliation: Department of Experimental Medicine.
authors.forename: A
authors.initials: A
authors.lastname: Gradilone
authors.affiliation: Department of Experimental Medicine, Division of Medical Oncology, 'Sapienza' University of Rome.
authors.forename: G
authors.initials: G
authors.lastname: Naso
authors.affiliation: Department of Experimental Medicine, Division of Medical Oncology, 'Sapienza' University of Rome.
authors.forename: C
authors.initials: C
authors.lastname: Raimondi
authors.affiliation: Department of Experimental Medicine, Division of Medical Oncology, 'Sapienza' University of Rome.
authors.forename: E
authors.initials: E
authors.lastname: Cortesi
authors.affiliation: Department of Experimental Medicine.
authors.forename: O
authors.initials: O
authors.lastname: Gandini
authors.affiliation: Division of Medical Oncology, University 'Campus Biomedico', Rome.
authors.forename: B
authors.initials: B
authors.lastname: Vincenzi
authors.affiliation: Division of Medical Oncology, Hospital 'S. Giovanni Evangelista', Tivoli, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Saltarelli
authors.affiliation: Division of Medical Oncology, Hospital 'S. Giovanni Evangelista', Tivoli, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Chiapparino
authors.affiliation: Division of Medical Oncology, Hospital 'S. Giovanni Evangelista', Tivoli, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Spremberg
authors.affiliation: Department of Medical Oncology, Fox Chase Cancer Center, Philadelphia, PA, USA.
authors.forename: M
authors.initials: M
authors.lastname: Cristofanilli
authors.affiliation: Department of Experimental Medicine; Department of Experimental Medicine, Division of Medical Oncology, 'Sapienza' University of Rome.
authors.forename: L
authors.initials: L
authors.lastname: Frati
authors.affiliation: Department of Experimental Medicine.
authors.forename: A M
authors.initials: AM
authors.lastname: Aglianò
authors.affiliation: Department of Experimental Medicine. Electronic address: paola.gazzaniga@uniroma1.it.
authors.forename: P
authors.initials: P
authors.lastname: Gazzaniga
mesh_terms: D000328:Adult; D000368:Aged; D000444:Aldehyde Dehydrogenase / Q000378:metabolism; D000080924:Aldehyde Dehydrogenase 1 Family; D001943:Breast Neoplasms / Q000097:blood* / Q000473:pathology*; D019008:Drug Resistance, Neoplasm; D047628:Estrogen Receptor alpha / Q000378:metabolism; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009360:Neoplastic Cells, Circulating / Q000378:metabolism* / Q000473:pathology*; D010641:Phenotype; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D050697:Retinal Dehydrogenase
chemical_list: D000444:Aldehyde Dehydrogenase; D000080924:Aldehyde Dehydrogenase 1 Family; D047628:Estrogen Receptor alpha; D007527:Isoenzymes; D018719:Erb-b2 Receptor Tyrosine Kinases; D050697:Retinal Dehydrogenase; C510223:ALDH1A1 protein, human