title: MYC copy gain, chromosomal instability and PI3K activation as potential markers of unfavourable outcome in trastuzumab-treated patients with metastatic breast cancer.
abstract: There is an unmet need for more efficient patient stratification for receiving trastuzumab in the metastatic breast cancer (mBC) setting, since only part of such patients benefit from the addition of this agent to chemotherapy. The aim of this study was to investigate the prognostic value of biomarkers including MYC and MET in mBC patients treated with trastuzumab-based regimens.
  
  
  
  mBC patients, locally tested as HER2-positive, treated with trastuzumab and chemotherapy between 1998 and 2010 were evaluated. Paraffin tumors (n = 229) were retrospectively centrally assessed by immunohistochemistry (IHC) for HER2, ER, PgR and Ki67; fluorescence in situ hybridization (FISH) for HER2, TOP2A and centromere (CEN) 17, MYC and CEN8, MET and CEN7; qPCR for MYC, MET copy number (CN); and, for PI3K activation (PIK3CA mutations; PTEN and phospho-mTOR protein expression). Increased CEN CN was assessed based on normal cut-offs. Time to progression (TTP) and survival were evaluated from the initiation of trastuzumab as first line treatment.
  
  
  
  Among all tumors, 90 were HER2-negative upon central testing (ambiguous HER2) and the rest were true HER2-positive. Further, 156 patients presented with mBC upon relapse of pre-treated disease (R-mBC) and 65 were diagnosed at stage IV (de novo mBC). Concordance between FISH and qPCR on gene CN status was fair for MYC (Kappa = 0.458) and absent for MET. The presence of MYC CN gain with qPCR and the absence of PI3K activation were infrequent events (7 and 8 % of evaluable tumors, respectively), while 41 % of tumors had increased CEN CN in one or more chromosomes, indicative of chromosomal instability. The most consistent finding in the entire cohort and in the above patient subgroups with respect to outcome was the unfavourable effect of MYC CN gain, which was retained upon multivariable analysis (e.g., survival in the entire cohort, HR 6.02; 95 % CI 2.67-13.6; p < 0.001). Further unfavourable prognosticators were increased CEN CN in one chromosome in R-mBC but not in de novo mBC (multivariable interaction p = 0.048), PI3K activation in R-mBC (multivariable p = 0.004) and increased Ki67 for patient TTP.
  
  
  
  MYC gene copies, centromere status and PI3K activation may adversely impact trastuzumab treated mBC patient outcome and seem worthy validating in larger series.
authors.affiliation: First Department of Medicine, Laiko General Hospital, National and Kapodistrian University of Athens School of Medicine, Athens, Greece. hgogas@hol.gr.
authors.forename: Helen
authors.initials: H
authors.lastname: Gogas
authors.affiliation: Department of Pathology, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece.|Laboratory of Molecular Oncology, Hellenic Foundation for Cancer Research/Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece.
authors.forename: Vassiliki
authors.initials: V
authors.lastname: Kotoula
authors.affiliation: Department of Biostatistics, Health Data Specialists Ltd, Athens, Greece.
authors.forename: Zoi
authors.initials: Z
authors.lastname: Alexopoulou
authors.affiliation: Second Department of Medical Oncology, Metropolitan Hospital, Piraeus, Greece.
authors.forename: Christos
authors.initials: C
authors.lastname: Christodoulou
authors.affiliation: Department of Pathology, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Kostopoulos
authors.affiliation: Laboratory of Molecular Oncology, Hellenic Foundation for Cancer Research/Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece.
authors.forename: Mattheos
authors.initials: M
authors.lastname: Bobos
authors.affiliation: Department of Pathology, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece.
authors.forename: Georgia
authors.initials: G
authors.lastname: Raptou
authors.affiliation: Laboratory of Molecular Oncology, Hellenic Foundation for Cancer Research/Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece.
authors.forename: Elpida
authors.initials: E
authors.lastname: Charalambous
authors.affiliation: Laboratory of Molecular Oncology, Hellenic Foundation for Cancer Research/Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece.
authors.forename: Eleftheria
authors.initials: E
authors.lastname: Tsolaki
authors.affiliation: Department of Medical Oncology, Papageorgiou Hospital, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Xanthakis
authors.affiliation: Department of Medical Oncology, Ioannina University Hospital, Ioannina, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Pentheroudakis
authors.affiliation: Division of Oncology, Department of Medicine, University Hospital, University of Patras Medical School, Patras, Greece.
authors.forename: Angelos
authors.initials: A
authors.lastname: Koutras
authors.affiliation: First Department of Medical Oncology, Metropolitan Hospital, Piraeus, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Bafaloukos
authors.affiliation: Oncology Unit, Hippokration Hospital, Athens, Greece.
authors.forename: Pavlos
authors.initials: P
authors.lastname: Papakostas
authors.affiliation: Second Department of Medical Oncology, Agii Anargiri Cancer Hospital, Athens, Greece.
authors.forename: Gerasimos
authors.initials: G
authors.lastname: Aravantinos
authors.affiliation: Division of Oncology, Second Department of Internal Medicine, Attikon University Hospital, Athens, Greece.
authors.forename: Amanda
authors.initials: A
authors.lastname: Psyrri
authors.affiliation: Pathology Department, Metropolitan Hospital, Piraeus, Greece.
authors.forename: Kalliopi
authors.initials: K
authors.lastname: Petraki
authors.affiliation: Laboratory of Molecular Oncology, Hellenic Foundation for Cancer Research/Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece.|Translational Research Section, Hellenic Cooperative Oncology Group, Data Office, Athens, Greece.
authors.forename: Konstantine T
authors.initials: KT
authors.lastname: Kalogeras
authors.affiliation: Oncology Section, Second Department of Internal Medicine, Hippokration Hospital, Athens, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Pectasides
authors.affiliation: Laboratory of Molecular Oncology, Hellenic Foundation for Cancer Research/Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece.|Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Fountzilas
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000473:pathology; D002503:Centromere / Q000378:metabolism; D043171:Chromosomal Instability / Q000235:genetics*; D015331:Cohort Studies; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D018628:Gene Dosage; D006801:Humans; D008875:Middle Aged; D015999:Multivariate Analysis; D009362:Neoplasm Metastasis; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D016016:Proportional Hazards Models; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D016019:Survival Analysis; D000068878:Trastuzumab / Q000494:pharmacology / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor; D019869:Phosphatidylinositol 3-Kinases; D016271:Proto-Oncogene Proteins c-myc; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; C508053:ERBB2 protein, human
keywords: Amplification; Centromere copy number; FISH; HER2; MET; MYC; Metastatic breast cancer; TOP2A; Trastuzumab; qPCR