title: Testing for ROS1 in non-small cell lung cancer: a review with recommendations.
abstract: Rearrangements of the ROS1 gene occur in 1-2 % of non-small cell lung cancers (NSCLCs). Crizotinib, a highly effective inhibitor of ROS1 kinase activity, is now FDA-approved for the treatment of patients with advanced ROS1-positive NSCLC. Consequently, focus on ROS1 testing is growing. Most laboratories currently rely on fluorescence in situ hybridisation (FISH) assays using a dual-colour break-apart probe to detect ROS1 rearrangements. Given the rarity of these rearrangements in NSCLC, detection of elevated ROS1 protein levels by immunohistochemistry may provide cost-effective screening prior to confirmatory FISH testing. Non-in situ testing approaches also hold potential as stand-alone methods or complementary tests, including multiplex real-time PCR assays and next-generation sequencing (NGS) platforms which include commercial test kits covering a range of fusion genes. In order to ensure high-quality biomarker testing, appropriate tissue handling, adequate control materials and participation in external quality assessment programmes are essential, irrespective of the testing technique employed. ROS1 testing is often only considered after negative tests for EGFR mutation and ALK gene rearrangement, based on the assumption that these oncogenic driver events tend to be exclusive. However, as the use of ROS1 inhibitors becomes routine, accurate and timely detection of ROS1 gene rearrangements will be critical for the optimal treatment of patients with NSCLC. As NGS techniques are introduced into routine diagnostic practice, ROS1 fusion gene testing will be provided as part of the initial testing package.
authors.affiliation: Institute of Pathology, University Hospital Basel, Basel, Switzerland.
authors.forename: Lukas
authors.initials: L
authors.lastname: Bubendorf
authors.affiliation: Institute of Pathology, University Hospital Cologne and Network Genomic Medicine, Cologne, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Büttner
authors.affiliation: Department of Pathology and Laboratory Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
authors.forename: Fouad
authors.initials: F
authors.lastname: Al-Dayel
authors.affiliation: Institute of Pathology, Charité Campus Mitte, Berlin, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Dietel
authors.affiliation: Department of Pathology and Cytology, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Göran
authors.initials: G
authors.lastname: Elmberger
authors.affiliation: Department of Pathology, Aberdeen University Medical School, Aberdeen, UK.
authors.forename: Keith
authors.initials: K
authors.lastname: Kerr
authors.affiliation: Laboratorio de Dianas Terapéuticas, Hospital Universitario HM Sanchinarro, C/Oña, 10, 28050, Madrid, Spain. flopezrios@hmhospitales.com.
authors.forename: Fernando
authors.identifier: http://orcid.org/0000-0001-6813-0395
authors.initials: F
authors.lastname: López-Ríos
authors.affiliation: Center of Predictive Molecular Medicine, University-Foundation, Chieti, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Marchetti
authors.affiliation: Cerrahpasa Medical Faculty, Istanbul University, Istanbul, Turkey.
authors.forename: Büge
authors.initials: B
authors.lastname: Öz
authors.affiliation: Institute of Pathology, University Hospital Antwerp, Edegem, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Pauwels
authors.affiliation: Department of Pathology, Centre Jean Perrin, Clermont-Ferrand, France.
authors.forename: Frédérique
authors.initials: F
authors.lastname: Penault-Llorca
authors.affiliation: Unit of Pathologic Anatomy, Azienda USL Valle d'Aosta, Aosta, Italy.
authors.forename: Giulio
authors.initials: G
authors.lastname: Rossi
authors.affiliation: The Fingerland Department of Pathology, Charles University Faculty of Medicine and Faculty Hospital in Hradec Kralove, Hradec Kralove, Czech Republic.
authors.forename: Aleš
authors.initials: A
authors.lastname: Ryška
authors.affiliation: Department of Pathology, VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Erik
authors.initials: E
authors.lastname: Thunnissen
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis* / Q000235:genetics*; D015321:Gene Rearrangement / Q000235:genetics*; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism; D009857:Oncogenes / Q000235:genetics*; D011505:Protein-Tyrosine Kinases / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics
chemical_list: D011518:Proto-Oncogene Proteins; D011505:Protein-Tyrosine Kinases; C062333:ROS1 protein, human; D020794:Receptor Protein-Tyrosine Kinases
keywords: Fluorescence in situ hybridisation; Immunohistochemistry; Non-small cell lung cancer; Predictive marker; ROS1; RT-PCR