title: Concordance of anaplastic lymphoma kinase (ALK) gene rearrangements between circulating tumor cells and tumor in non-small cell lung cancer.
abstract: Anaplastic lymphoma kinase (ALK) gene rearrangement in non-small cell lung cancer (NSCLC) is routinely evaluated by fluorescent in-situ hybridization (FISH) testing on biopsy tissues. Testing can be challenging however, when suitable tissue samples are unavailable. We examined the relevance of circulating tumor cells (CTC) as a surrogate for biopsy-based FISH testing. We assessed paired tumor and CTC samples from patients with ALK rearranged lung cancer (n = 14), ALK-negative lung cancer (n = 12), and healthy controls (n = 5) to derive discriminant CTC counts, and to compare ALK rearrangement patterns. Blood samples were enriched for CTCs to be used for ALK FISH testing. ALK-positive CTCs counts were higher in ALK-positive NSCLC patients (3-15 cells/1.88 mL of blood) compared with ALK-negative NSCLC patients and healthy donors (0-2 cells/1.88 mL of blood). The latter range was validated as the 'false positive' cutoff for ALK FISH testing of CTCs. ALK FISH signal patterns observed on tumor biopsies were recapitulated in CTCs in all cases. Sequential CTC counts in an index case of lung cancer with no evaluable tumor tissue treated with crizotinib showed six, three and eleven ALK-positive CTCs per 1.88 mL blood at baseline, partial response and post-progression time points, respectively. Furthermore, ALK FISH rearrangement suggestive of gene copy number increase was observed in CTCs following progression. Recapitulation of ALK rearrangement patterns in the tumor on CTCs, suggested that CTCs might be used to complement tissue-based ALK testing in NSCLC to guide ALK-targeted therapy when suitable tissue biopsy samples are unavailable for testing.
authors.affiliation: Department of Pathology, Singapore General Hospital, Singapore.
authors.forename: Chye Ling
authors.initials: CL
authors.lastname: Tan
authors.affiliation: Department of Pathology, Singapore General Hospital, Singapore.
authors.forename: Tse Hui
authors.initials: TH
authors.lastname: Lim
authors.affiliation: Department of Pathology, Singapore General Hospital, Singapore.
authors.forename: Tony Kh
authors.initials: TKh
authors.lastname: Lim
authors.affiliation: Department of Medical Oncology, National Cancer Center Singapore, Singapore.
authors.forename: Daniel Shao-Weng
authors.initials: DS
authors.lastname: Tan
authors.affiliation: Department of Pathology, Singapore General Hospital, Singapore.
authors.forename: Yong Wei
authors.initials: YW
authors.lastname: Chua
authors.affiliation: Department of Medical Oncology, National Cancer Center Singapore, Singapore.
authors.forename: Mei Kim
authors.initials: MK
authors.lastname: Ang
authors.affiliation: Department of Molecular Oncology, National University Health System Singapore, Singapore.
authors.forename: Brendan
authors.initials: B
authors.lastname: Pang
authors.affiliation: Faculty of Engineering, Department of Biomedical Engineering, National University of Singapore, Singapore.|Mechanobiology Institute, National University of Singapore, Singapore.
authors.forename: Chwee Teck
authors.initials: CT
authors.lastname: Lim
authors.affiliation: Department of Pathology, Singapore General Hospital, Singapore.
authors.forename: Angela
authors.initials: A
authors.lastname: Takano
authors.affiliation: Department of Pathology, Singapore General Hospital, Singapore.
authors.forename: Alvin Soon-Tiong
authors.initials: AS
authors.lastname: Lim
authors.affiliation: Clearbridge Biomedics Pte Ltd., Singapore.
authors.forename: Man Chun
authors.initials: MC
authors.lastname: Leong
authors.affiliation: Department of Medical Oncology, National Cancer Center Singapore, Singapore.|Institute of Molecular and Cell Biology, Singapore.
authors.forename: Wan-Teck
authors.initials: WT
authors.lastname: Lim
mesh_terms: D000230:Adenocarcinoma / Q000097:blood / Q000235:genetics* / Q000473:pathology; D000328:Adult; D000368:Aged; D000077548:Anaplastic Lymphoma Kinase; D014408:Biomarkers, Tumor / Q000097:blood / Q000235:genetics*; D002289:Carcinoma, Non-Small-Cell Lung / Q000097:blood / Q000235:genetics* / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D015321:Gene Rearrangement; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008175:Lung Neoplasms / Q000097:blood / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009360:Neoplastic Cells, Circulating / Q000473:pathology*; D011379:Prognosis; D020794:Receptor Protein-Tyrosine Kinases / Q000097:blood / Q000235:genetics*
chemical_list: D014408:Biomarkers, Tumor; C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D020794:Receptor Protein-Tyrosine Kinases
keywords: ALK-gene rearrangement; circulating tumor cells; fluorescent in-situ hybridization; lung cancer; molecular diagnosis