title: Chromogenic in situ hybridization is a reliable assay for detection of ALK rearrangements in adenocarcinomas of the lung.
abstract: Reliable detection of anaplastic lymphoma kinase (ALK) rearrangements is a prerequisite for personalized treatment of lung cancer patients, as ALK rearrangements represent a predictive biomarker for the therapy with specific tyrosine kinase inhibitors. Currently, fluorescent in situ hybridization (FISH) is considered to be the standard method for assessing formalin-fixed and paraffin-embedded tissue for ALK inversions and translocations. However, FISH requires a specialized equipment, the signals fade rapidly and it is difficult to detect overall morphology and tumor heterogeneity. Chromogenic in situ hybridization (CISH) has been successfully introduced as an alternative test for the detection of several genetic aberrations. This study validates a newly developed ALK CISH assay by comparing FISH and CISH signal patterns in lung cancer samples with and without ALK rearrangements. One hundred adenocarcinomas of the lung were included in this study, among them 17 with known ALK rearrangement. FISH and CISH were carried out and evaluated according to the manufacturers' recommendations. For both assays, tumors were considered positive if ≥15% of tumor cells showed either isolated 3' signals or break-apart patterns or a combination of both. A subset of tumors was exemplarily examined by using a novel EML4 (echinoderm microtubule-associated protein-like 4) CISH probe. Red, green and fusion CISH signals were clearcut and different signal patterns were easily recognized. The percentage of aberrant tumor cells was statistically highly correlated (P<0.001) between FISH and CISH. On the basis of 86 samples that were evaluable by ALK CISH, we found a 100% sensitivity and 100% specificity of this assay. Furthermore, EML4 rearrangements could be recognized by CISH. CISH is a highly reliable, sensitive and specific method for the detection of ALK gene rearrangements in pulmonary adenocarcinomas. Our results suggest that CISH might serve as a suitable alternative to FISH, which is the current gold standard.
authors.affiliation: Institute of Pathology, University Hospital Cologne (as part of the Lung Cancer Group Cologne (LCGC)), Cologne, Germany.
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Schildhaus
authors.forename: Karl-Friedrich
authors.initials: KF
authors.lastname: Deml
authors.forename: Katja
authors.initials: K
authors.lastname: Schmitz
authors.forename: Maren
authors.initials: M
authors.lastname: Meiboom
authors.forename: Elke
authors.initials: E
authors.lastname: Binot
authors.forename: Sven
authors.initials: S
authors.lastname: Hauke
authors.forename: Sabine
authors.initials: S
authors.lastname: Merkelbach-Bruse
authors.forename: Reinhard
authors.initials: R
authors.lastname: Büttner
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D000077192:Adenocarcinoma of Lung; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000077548:Anaplastic Lymphoma Kinase; D014408:Biomarkers, Tumor / Q000235:genetics*; D018797:Cell Cycle Proteins / Q000235:genetics; D002863:Chromogenic Compounds; D004252:DNA Mutational Analysis; D066246:ErbB Receptors / Q000235:genetics; D005240:Feasibility Studies; D005260:Female; D015321:Gene Rearrangement; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing / Q000379:methods*; D006801:Humans; D017403:In Situ Hybridization; D017404:In Situ Hybridization, Fluorescence; D008175:Lung Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D008297:Male; D008869:Microtubule-Associated Proteins / Q000235:genetics; D008875:Middle Aged; D009154:Mutation; D010641:Phenotype; D011237:Predictive Value of Tests; D011518:Proto-Oncogene Proteins / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D015203:Reproducibility of Results; D012697:Serine Endopeptidases / Q000235:genetics; D012815:Signal Processing, Computer-Assisted; D018631:ras Proteins / Q000235:genetics
chemical_list: D014408:Biomarkers, Tumor; D018797:Cell Cycle Proteins; D002863:Chromogenic Compounds; C117307:KRAS protein, human; D008869:Microtubule-Associated Proteins; D011518:Proto-Oncogene Proteins; C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; C512478:EGFR protein, human; D066246:ErbB Receptors; D020794:Receptor Protein-Tyrosine Kinases; C415585:EML4 protein, human; D012697:Serine Endopeptidases; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins