title: Amphiregulin and epiregulin mRNA expression in primary tumors predicts outcome in metastatic colorectal cancer treated with cetuximab.
abstract: OBJECTIVE
  To study the power of the epidermal growth factor receptor (EGFR) epiregulin (EREG) and amphiregulin (AREG) ligands' expression in primary tumors to predict the outcome in patients with chemorefractory metastatic colorectal cancer (cmCRC) treated with the combination of cetuximab and irinotecan.
  
  
  METHODS
  Gene expression measurements and KRAS mutation analysis were performed on archival formalin-fixed paraffin-embedded primary tumors of 220 cmCRC patients. Response was measured using RECIST (Response Evaluation Criteria in Solid Tumors) criteria. The relation between ligand expression levels and outcome was evaluated using logistic regression for response and Cox regression for survival data. Receiver operating characteristics analysis was performed for response and survival data. CIs for the performance indices were obtained with a nonparametric bootstrap procedure. Findings were externally validated on a series of 67 samples treated in a similar setting.
  
  
  RESULTS
  In KRAS wild type (WT) patients, there was a significant association between log-transformed ligand expression and response for EREG (odds ratio for objective response, 1.90; 95% CI, 1.27 to 2.83; P = .0005; concordance index [c-index], 0.681) and for AREG (odds ratio for objective response, 1.862; 95% CI, 1.22 to 2.72; P = .0017; c-index, 0.673). In a Cox regression model, dichotomized ligand expression was significantly associated with progression-free survival (PFS) and overall survival (OS). EREG PFS hazard ratio (HR) was 0.41 (95% CI, 0.274 to 0.609; P < .001; time-dependent c-index [Ctau index], 0.640), and AREG PFS HR was 0.43 (95% CI, 0.29 to 0.64; P < .001; Ctau index, 0.627). EREG OS HR was 0.42 (95% CI, 0.28 to 0.63; P < .0001; Ctau index, 0.639), and AREG OS HR was 0.40 (95% CI, 0.27 to 0.64; P < .0001; Ctau index, 0.625). There was no predictive power of ligand expression in patients with KRAS mutation.
  
  
  CONCLUSIONS
  Expression of EGFR ligands in primary tumors significantly predicts outcome in KRAS WT cmCRC treated with cetuximab and irinotecan.
authors.affiliation: Department of Pathology, Digestive Oncology Unit, University Hospital Gasthuisberg, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Jacobs
authors.forename: Wendy
authors.initials: W
authors.lastname: De Roock
authors.forename: Hubert
authors.initials: H
authors.lastname: Piessevaux
authors.forename: Robin
authors.initials: R
authors.lastname: Van Oirbeek
authors.forename: Bart
authors.initials: B
authors.lastname: Biesmans
authors.forename: Jef
authors.initials: J
authors.lastname: De Schutter
authors.forename: Steffen
authors.initials: S
authors.lastname: Fieuws
authors.forename: Jo
authors.initials: J
authors.lastname: Vandesompele
authors.forename: Marc
authors.initials: M
authors.lastname: Peeters
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Van Laethem
authors.forename: Yves
authors.initials: Y
authors.lastname: Humblet
authors.forename: Frederique
authors.initials: F
authors.lastname: Pénault-Llorca
authors.forename: Gert
authors.initials: G
authors.lastname: De Hertogh
authors.forename: Pierre
authors.initials: P
authors.lastname: Laurent-Puig
authors.forename: Eric
authors.initials: E
authors.lastname: Van Cutsem
authors.forename: Sabine
authors.initials: S
authors.lastname: Tejpar
mesh_terms: D066258:Amphiregulin; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002166:Camptothecin / Q000031:analogs & derivatives / Q000627:therapeutic use; D000068818:Cetuximab; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000401:mortality / Q000556:secondary; D066255:EGF Family of Proteins; D004815:Epidermal Growth Factor / Q000235:genetics*; D066260:Epiregulin; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics; D015870:Gene Expression; D006023:Glycoproteins / Q000096:biosynthesis* / Q000235:genetics*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis* / Q000235:genetics*; D000077146:Irinotecan; D008024:Ligands; D011379:Prognosis; D011518:Proto-Oncogene Proteins / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D012333:RNA, Messenger / Q000235:genetics; D016019:Survival Analysis; D018631:ras Proteins / Q000235:genetics
chemical_list: C587848:AREG protein, human; D066258:Amphiregulin; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D066255:EGF Family of Proteins; C587880:EREG protein, human; D066260:Epiregulin; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; C117307:KRAS protein, human; D008024:Ligands; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D004815:Epidermal Growth Factor; D000077146:Irinotecan; D066246:ErbB Receptors; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins; D000068818:Cetuximab; D002166:Camptothecin