title: Detection of circulating tumor cells harboring a unique ALK rearrangement in ALK-positive non-small-cell lung cancer.
abstract: OBJECTIVE
  The diagnostic test for ALK rearrangement in non-small-cell lung cancer (NSCLC) for crizotinib treatment is currently done on tumor biopsies or fine-needle aspirations. We evaluated whether ALK rearrangement diagnosis could be performed by using circulating tumor cells (CTCs).
  
  
  METHODS
  The presence of an ALK rearrangement was examined in CTCs of 18 ALK-positive and 14 ALK-negative patients by using a filtration enrichment technique and filter-adapted fluorescent in situ hybridization (FA-FISH), a FISH method optimized for filters. ALK-rearrangement patterns were determined in CTCs and compared with those present in tumor biopsies. ALK-rearranged CTCs and tumor specimens were characterized for epithelial (cytokeratins, E-cadherin) and mesenchymal (vimentin, N-cadherin) marker expression. ALK-rearranged CTCs were monitored in five patients treated with crizotinib.
  
  
  RESULTS
  All ALK-positive patients had four or more ALK-rearranged CTCs per 1 mL of blood (median, nine CTCs per 1 mL; range, four to 34 CTCs per 1 mL). No or only one ALK-rearranged CTC (median, one per 1 mL; range, zero to one per 1 mL) was detected in ALK-negative patients. ALK-rearranged CTCs harbored a unique (3'5') split pattern, and heterogeneous patterns (3'5', only 3') of splits were present in tumors. ALK-rearranged CTCs expressed a mesenchymal phenotype contrasting with heterogeneous epithelial and mesenchymal marker expressions in tumors. Variations in ALK-rearranged CTC levels were detected in patients being treated with crizotinib.
  
  
  CONCLUSIONS
  ALK rearrangement can be detected in CTCs of patients with ALK-positive NSCLC by using a filtration technique and FA-FISH, enabling both diagnostic testing and monitoring of crizotinib treatment. Our results suggest that CTCs harboring a unique ALK rearrangement and mesenchymal phenotype may arise from clonal selection of tumor cells that have acquired the potential to drive metastatic progression of ALK-positive NSCLC.
authors.affiliation: Institut de Cancérologie Gustave Roussy, Villejuif, France.
authors.forename: Emma
authors.initials: E
authors.lastname: Pailler
authors.forename: Julien
authors.initials: J
authors.lastname: Adam
authors.forename: Amélie
authors.initials: A
authors.lastname: Barthélémy
authors.forename: Marianne
authors.initials: M
authors.lastname: Oulhen
authors.forename: Nathalie
authors.initials: N
authors.lastname: Auger
authors.forename: Alexander
authors.initials: A
authors.lastname: Valent
authors.forename: Isabelle
authors.initials: I
authors.lastname: Borget
authors.forename: David
authors.initials: D
authors.lastname: Planchard
authors.forename: Melissa
authors.initials: M
authors.lastname: Taylor
authors.forename: Fabrice
authors.initials: F
authors.lastname: André
authors.forename: Jean Charles
authors.initials: JC
authors.lastname: Soria
authors.forename: Philippe
authors.initials: P
authors.lastname: Vielh
authors.forename: Benjamin
authors.initials: B
authors.lastname: Besse
authors.forename: Françoise
authors.initials: F
authors.lastname: Farace
mesh_terms: D000328:Adult; D000368:Aged; D000077548:Anaplastic Lymphoma Kinase; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D000077547:Crizotinib; D005260:Female; D015321:Gene Rearrangement; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D007633:Keratins / Q000235:genetics / Q000378:metabolism; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D061986:MCF-7 Cells; D008297:Male; D008875:Middle Aged; D009360:Neoplastic Cells, Circulating / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use; D011720:Pyrazoles / Q000627:therapeutic use; D011725:Pyridines / Q000627:therapeutic use; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D014746:Vimentin / Q000235:genetics / Q000378:metabolism
chemical_list: D015820:Cadherins; D047428:Protein Kinase Inhibitors; D011720:Pyrazoles; D011725:Pyridines; D014746:Vimentin; D000077547:Crizotinib; D007633:Keratins; C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D020794:Receptor Protein-Tyrosine Kinases