title: High level of chromosomal instability in circulating tumor cells of ROS1-rearranged non-small-cell lung cancer.
abstract: BACKGROUND
  Genetic aberrations affecting the c-ros oncogene 1 (ROS1) tyrosine kinase gene have been reported in a small subset of patients with non-small-cell lung cancer (NSCLC). We evaluated whether ROS1-chromosomal rearrangements could be detected in circulating tumor cells (CTCs) and examined tumor heterogeneity of CTCs and tumor biopsies in ROS1-rearranged NSCLC patients.
  
  
  METHODS
  Using isolation by size of epithelial tumor cells (ISET) filtration and filter-adapted-fluorescence in situ hybridization (FA-FISH), ROS1 rearrangement was examined in CTCs from four ROS1-rearranged patients treated with the ROS1-inhibitor, crizotinib, and four ROS1-negative patients. ROS1-gene alterations observed in CTCs at baseline from ROS1-rearranged patients were compared with those present in tumor biopsies and in CTCs during crizotinib treatment. Numerical chromosomal instability (CIN) of CTCs was assessed by DNA content quantification and chromosome enumeration.
  
  
  RESULTS
  ROS1 rearrangement was detected in the CTCs of all four patients with ROS1 rearrangement previously confirmed by tumor biopsy. In ROS1-rearranged patients, median number of ROS1-rearranged CTCs at baseline was 34.5 per 3 ml blood (range, 24-55). In ROS1-negative patients, median background hybridization of ROS1-rearranged CTCs was 7.5 per 3 ml blood (range, 7-11). Tumor heterogeneity, assessed by ROS1 copy number, was significantly higher in baseline CTCs compared with paired tumor biopsies in the three patients experiencing PR or SD (P < 0.0001). Copy number in ROS1-rearranged CTCs increased significantly in two patients who progressed during crizotinib treatment (P < 0.02). CTCs from ROS1-rearranged patients had a high DNA content and gain of chromosomes, indicating high levels of aneuploidy and numerical CIN.
  
  
  CONCLUSIONS
  We provide the first proof-of-concept that CTCs can be used for noninvasive and sensitive detection of ROS1 rearrangement in NSCLC patients. CTCs from ROS1-rearranged patients show considerable heterogeneity of ROS1-gene abnormalities and elevated numerical CIN, a potential mechanism to escape ROS1-inhibitor therapy in ROS1-rearranged NSCLC tumors.
authors.affiliation: INSERM U981 "Identification of Molecular Predictors and new Targets for Cancer Treatment", University of Paris-Sud XI, Gustave Roussy, Villejuif Translational Research Laboratory, Gustave Roussy, Villejuif.
authors.forename: E
authors.initials: E
authors.lastname: Pailler
authors.affiliation: Departments of Biopathology, Gustave Roussy, Villejuif, France.
authors.forename: N
authors.initials: N
authors.lastname: Auger
authors.affiliation: INSERM U981 "Identification of Molecular Predictors and new Targets for Cancer Treatment", University of Paris-Sud XI, Gustave Roussy, Villejuif Translational Research Laboratory, Gustave Roussy, Villejuif.
authors.forename: C R
authors.initials: CR
authors.lastname: Lindsay
authors.affiliation: INSERM U981 "Identification of Molecular Predictors and new Targets for Cancer Treatment", University of Paris-Sud XI, Gustave Roussy, Villejuif Translational Research Laboratory, Gustave Roussy, Villejuif Departments of Biopathology, Gustave Roussy, Villejuif, France.
authors.forename: P
authors.initials: P
authors.lastname: Vielh
authors.affiliation: Translational Research Laboratory, Gustave Roussy, Villejuif.
authors.forename: A
authors.initials: A
authors.lastname: Islas-Morris-Hernandez
authors.affiliation: Biostatistics and Epidemiology, Gustave Roussy, Villejuif, France.
authors.forename: I
authors.initials: I
authors.lastname: Borget
authors.affiliation: Medicine, Gustave Roussy, Villejuif, France.
authors.forename: M
authors.initials: M
authors.lastname: Ngo-Camus
authors.affiliation: Medicine, Gustave Roussy, Villejuif, France.
authors.forename: D
authors.initials: D
authors.lastname: Planchard
authors.affiliation: INSERM U981 "Identification of Molecular Predictors and new Targets for Cancer Treatment", University of Paris-Sud XI, Gustave Roussy, Villejuif Medicine, Gustave Roussy, Villejuif, France.
authors.forename: J-C
authors.initials: JC
authors.lastname: Soria
authors.affiliation: Medicine, Gustave Roussy, Villejuif, France.
authors.forename: B
authors.initials: B
authors.lastname: Besse
authors.affiliation: INSERM U981 "Identification of Molecular Predictors and new Targets for Cancer Treatment", University of Paris-Sud XI, Gustave Roussy, Villejuif Translational Research Laboratory, Gustave Roussy, Villejuif francoise.farace@gustaveroussy.fr.
authors.forename: F
authors.initials: F
authors.lastname: Farace
mesh_terms: D000328:Adult; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000097:blood / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D043171:Chromosomal Instability; D000077547:Crizotinib; D005260:Female; D005500:Follow-Up Studies; D015321:Gene Rearrangement; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008175:Lung Neoplasms / Q000097:blood / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009360:Neoplastic Cells, Circulating / Q000473:pathology*; D011379:Prognosis; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use; D011505:Protein-Tyrosine Kinases / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D011720:Pyrazoles / Q000627:therapeutic use; D011725:Pyridines / Q000627:therapeutic use; D014407:Tumor Cells, Cultured
chemical_list: D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D011720:Pyrazoles; D011725:Pyridines; D000077547:Crizotinib; D011505:Protein-Tyrosine Kinases; C062333:ROS1 protein, human
keywords: FA-FISH; ROS1-rearranged non-small-cell lung cancer; circulating tumor cells; filtration enrichment; predictive biomarker
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