title: On the relevance of a testing algorithm for the detection of ROS1-rearranged lung adenocarcinomas.
abstract: OBJECTIVE
  ROS1 proto-oncogene translocations define a new molecular subgroup in non-small cell lung cancers (NSCLC) and are associated with a response to the MET/ALK inhibitor, crizotinib. These rearrangements are described in 0.9-1.7% NSCLC, in wild-type EGFR, KRAS and ALK ("triple negative") lung adenocarcinomas. Rapid and efficient identification of these alterations is thus becoming increasingly important.
  
  
  METHODS
  In this study, 121 triple negative lung adenocarcinomas were screened by both IHC with the ROS1 D4D6 antibody, and FISH using two commercially available ROS1 break-apart probes. To address a possible cross-reactivity of the ROS1 antibody with other protein kinase receptors, we screened 80 additional cases with known EGFR, KRAS, PI3KCA, BRAF, HER2 mutations or ALK-rearrangement.
  
  
  RESULTS
  We diagnosed 9 ROS1-rearranged adenocarcinomas, with both a positive FISH result (51-87% rearranged nuclei) and a positive IHC staining (2+/3+ cytoplasmic staining). Only one of the ROS1-positive FISH cases was characterized by a classical split pattern, the others showed a variant pattern, most commonly involving a loss of the 5' telomeric probe. Considering a positivity threshold of 2+ stained cells, the sensitivity of the ROS1 D4D6 antibody compared to FISH was 100% and the specificity 96.9%, as two HER2-mutated tumors were positive with D4D6 antibody, without any translocation in FISH. All the ROS1-positive cases were at an advanced stage, arising in never or light smokers. They were mainly solid cribriform and acinar adenocarcinomas, with signet ring cells noted in 5 cases, and calcifications in 3 cases. One positive case was an invasive mucinous carcinoma.
  
  
  CONCLUSIONS
  Our results show that a screening algorithm based on an IHC detection of ROS1 fusion proteins, confirmed if positive or doubtful by a ROS1 break-apart FISH assay, is pertinent in advanced "triple negative" lung adenocarcinomas, since the prevalence of ROS1-positive cases in this selected population reaches 7.4% in our series.
authors.affiliation: Département d'Anatomie et Cytologie Pathologiques, Pôle de Biologie et Pathologie, CHU Grenoble, France; Plateforme de Génétique Moléculaire des Tumeurs, Pôle de Biologie et Pathologie, CHU Grenoble, France.
authors.forename: Lénaïg
authors.initials: L
authors.lastname: Mescam-Mancini
authors.affiliation: Département d'Anatomie et Cytologie Pathologiques, Pôle de Biologie et Pathologie, CHU Grenoble, France; Plateforme de Génétique Moléculaire des Tumeurs, Pôle de Biologie et Pathologie, CHU Grenoble, France; INSERM U 823-Institut A Bonniot-Université J Fourier, Grenoble, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Lantuéjoul
authors.affiliation: Pôle de médecine aigue communautaire, Unité d'oncologie thoracique, CHU Grenoble, France; INSERM U 823-Institut A Bonniot-Université J Fourier, Grenoble, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Moro-Sibilot
authors.affiliation: Département d'Anatomie et Cytologie Pathologiques, CHU Toulouse, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Rouquette
authors.affiliation: Servie de Pneumologie, CH Lyon Sud, France.
authors.forename: Pierre-Jean
authors.initials: PJ
authors.lastname: Souquet
authors.affiliation: Service de Pneumologie, CH Toulon, France.
authors.forename: Clarisse
authors.initials: C
authors.lastname: Audigier-Valette
authors.affiliation: Département d'Anatomie et Cytologie Pathologiques, CHU Rouen, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Sabourin
authors.affiliation: Service de Pneumologie, Centre Hospitalier de la Région d'Annecy, Annecy, France.
authors.forename: Chantal
authors.initials: C
authors.lastname: Decroisette
authors.affiliation: Pôle de médecine aigue communautaire, Unité d'oncologie thoracique, CHU Grenoble, France.
authors.forename: Linda
authors.initials: L
authors.lastname: Sakhri
authors.affiliation: Département d'Anatomie et Cytologie Pathologiques, Pôle de Biologie et Pathologie, CHU Grenoble, France; INSERM U 823-Institut A Bonniot-Université J Fourier, Grenoble, France.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Brambilla
authors.affiliation: Département d'Anatomie et Cytologie Pathologiques, Pôle de Biologie et Pathologie, CHU Grenoble, France; Plateforme de Génétique Moléculaire des Tumeurs, Pôle de Biologie et Pathologie, CHU Grenoble, France; INSERM U 823-Institut A Bonniot-Université J Fourier, Grenoble, France. Electronic address: AFlorin@chu-grenoble.fr.
authors.forename: Anne
authors.initials: A
authors.lastname: McLeer-Florin
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000235:genetics; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000077548:Anaplastic Lymphoma Kinase; D000911:Antibodies, Monoclonal / Q000378:metabolism; D055088:Early Detection of Cancer / Q000379:methods* / Q000592:standards; D066246:ErbB Receptors / Q000235:genetics; D005260:Female; D015321:Gene Rearrangement; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D016283:Proto-Oncogene Proteins p21(ras); D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics; D012680:Sensitivity and Specificity; D018631:ras Proteins / Q000235:genetics
chemical_list: D000911:Antibodies, Monoclonal; C117307:KRAS protein, human; C000715470:MAS1 protein, human; D015514:Oncogene Proteins, Fusion; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; C000626173:ALK protein, human; C000626175:Alk protein, rat; D000077548:Anaplastic Lymphoma Kinase; C512478:EGFR protein, human; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; C062333:ROS1 protein, human; D020794:Receptor Protein-Tyrosine Kinases; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins
keywords: ALK; EGFR; FISH; IHC; Immunohistochemistry; KRAS; Lung adenocarcinoma; ROS1; Targeted therapy; Testing algorithm; anaplastic lymphoma kinase; c-ros oncogene-1; epidermal growth factor receptor; fluorescent in situ hybridization; immunohistochemistry; v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog