title: Epidermal Growth Factor Receptor (EGFR) gene copy number (GCN) correlates with clinical activity of irinotecan-cetuximab in K-RAS wild-type colorectal cancer: a fluorescence in situ (FISH) and chromogenic in situ hybridization (CISH) analysis.
abstract: BACKGROUND
  K-RAS wild type colorectal tumors show an improved response rate to anti-EGFR monoclonal antibodies. Nevertheless 70% to 40% of these patients still does not seem to benefit from this therapeutic approach. FISH EGFR GCN has been previously demonstrated to correlate with clinical outcome of colorectal cancer treated with anti-EGFR monoclonal antibodies. CISH also seemed able to provide accurate EGFR GCN information with the advantage of a simpler and reproducible technique involving immunohistochemistry and light microscopy. Based on these findings we investigated the correlation between both FISH and CISH EGFR GCN and clinical outcome in K-RAS wild-type colorectal cancer treated with irinotecan-cetuximab.
  
  
  METHODS
  Patients with advanced K-RAS wild-type, colorectal cancer receiving irinotecan-cetuximab after failure of irinotecan-based chemotherapy were eligible. A cut-off value for EGFR GCN of 2.6 and 2.12 for FISH and CISH respectively was derived from ROC curve analysis.
  
  
  RESULTS
  Forty-four patients were available for analysis. We observed a partial remission in 9 (60%) and 2 (9%) cases with a FISH EGFR GCN >or= 2.6 and < 2.6 respectively (p = 0.002) and in 10 (36%) and 1 (6%) cases with a CISH EGFR GCN >or= 2.12 and < 2.12 respectively (p = 0.03). Median TTP was 7.7 and 6.4 months in patients showing increased FISH and CISH EGFR GCN whereas it was 2.9 and 3.1 months in those with low FISH and CISH EGFR GCN (p = 0.04 and 0.02 respectively).
  
  
  CONCLUSIONS
  FISH and CISH EGFR GCN may both represent effective tools for a further patients selection in K-RAS wild-type colorectal cancer treated with cetuximab.
authors.affiliation: Clinica di Oncologia Medica, AO Ospedali Riuniti-Università Politecnica delle Marche, Ancona, Italy. marioscartozzi@libero.it
authors.forename: Mario
authors.initials: M
authors.lastname: Scartozzi
authors.forename: Italo
authors.initials: I
authors.lastname: Bearzi
authors.forename: Alessandra
authors.initials: A
authors.lastname: Mandolesi
authors.forename: Chiara
authors.initials: C
authors.lastname: Pierantoni
authors.forename: Fotios
authors.initials: F
authors.lastname: Loupakis
authors.forename: Alberto
authors.initials: A
authors.lastname: Zaniboni
authors.forename: Francesca
authors.initials: F
authors.lastname: Negri
authors.forename: Antonello
authors.initials: A
authors.lastname: Quadri
authors.forename: Fausto
authors.initials: F
authors.lastname: Zorzi
authors.forename: Eva
authors.initials: E
authors.lastname: Galizia
authors.forename: Rossana
authors.initials: R
authors.lastname: Berardi
authors.forename: Tommasina
authors.initials: T
authors.lastname: Biscotti
authors.forename: Roberto
authors.initials: R
authors.lastname: Labianca
authors.forename: Gianluca
authors.initials: G
authors.lastname: Masi
authors.forename: Alfredo
authors.initials: A
authors.lastname: Falcone
authors.forename: Stefano
authors.initials: S
authors.lastname: Cascinu
mesh_terms: D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D061067:Antibodies, Monoclonal, Humanized; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage*; D002166:Camptothecin / Q000008:administration & dosage / Q000031:analogs & derivatives; D000068818:Cetuximab; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000235:genetics*; D066246:ErbB Receptors / Q000235:genetics* / Q000378:metabolism; D005260:Female; D018628:Gene Dosage; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D017403:In Situ Hybridization; D017404:In Situ Hybridization, Fluorescence; D000077146:Irinotecan; D008297:Male; D008875:Middle Aged; D009154:Mutation; D012189:Retrospective Studies; D017211:Treatment Failure; D018631:ras Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000077146:Irinotecan; D066246:ErbB Receptors; D018631:ras Proteins; D000068818:Cetuximab; D002166:Camptothecin