title: In situ quantitative measurement of HER2mRNA predicts benefit from trastuzumab-containing chemotherapy in a cohort of metastatic breast cancer patients.
abstract: BACKGROUND
  We sought to determine the predictive value of in situ mRNA measurement compared to traditional methods on a cohort of trastuzumab-treated metastatic breast cancer patients.
  
  
  METHODS
  A tissue microarray composed of 149, classified as HER2-positive, metastatic breast cancers treated with various trastuzumab-containing chemotherapy regimens was constructed. HER2 intracellular domain(ICD), HER2 extracellular domain(ECD) and HER2 mRNA were assessed using AQUA. For HER2 protein evaluation, CB11 was used to measure ICD and SP3 to measure ECD of the HER2 receptor. In addition, HER2 mRNA status was assessed using RNAscope assay ERRB2 probe. Kaplan - Meier estimates were used for depicting time-to-event endpoints. Multivariate Cox regression models with backward elimination were used to assess the performance of markers as predictors of TTP and OS, after adjusting for important covariates.
  
  
  RESULTS
  HER2 mRNA was correlated with ICD HER2, as measured by CB11 HER2, with ECD HER2 as measured by SP3 (Pearson's Correlation Coefficient, r = 0.66 and 0.51 respectively) and with FISH HER2 (Spearman's Correlation Coefficient, r = 0.75). All markers, HER2 mRNA, ICD HER2 and ECD HER2, along with FISH HER2, were found prognostic for OS (Log-rank p = 0.007, 0.005, 0.009 and 0.043 respectively), and except for FISH HER2, they were also prognostic for TTP Log-rank p = 0.036, 0.068 and 0.066 respectively) in this trastuzumab- treated cohort. Multivariate analysis showed that in the presence of pre-specified set of prognostic factors, among all biomarkers only ECD HER2, as measured by SP3, is strong prognostic factor for both TTP (HR = 0.54, 95% CI: 0.31-0.93, p = 0.027) and OS (HR = 0.39, 95%CI: 0.22-0.70, p = 0.002).
  
  
  CONCLUSIONS
  The expression of HER2 ICD and ECD as well as HER2 mRNA levels was significantly associated with TTP and OS in this trastuzumab-treated metastatic cohort. In situ assessment of HER2 mRNA has the potential to identify breast cancer patients who derive benefit from Trastuzumab treatment.
authors: Yale University, School of Medicine, Department of Pathology, New Haven, Connecticut, United States of America.
authors: Maria
authors: M
authors: Vassilakopoulou
authors: Yale University, School of Public Health, Department of Biostatistics, New Haven, Connecticut, United States of America.
authors: Taiwo
authors: T
authors: Togun
authors: Laboratory of Biostatistics, University of Athens School of Nursing, Athens, Greece.
authors: Urania
authors: U
authors: Dafni
authors: Yale University, School of Medicine, Department of Pathology, New Haven, Connecticut, United States of America.
authors: Huan
authors: H
authors: Cheng
authors: Yale University, School of Medicine, Department of Pathology, New Haven, Connecticut, United States of America.
authors: Jennifer
authors: J
authors: Bordeaux
authors: Yale University, School of Medicine, Department of Pathology, New Haven, Connecticut, United States of America.
authors: Veronique M
authors: VM
authors: Neumeister
authors: Laboratory of Molecular Oncology, Hellenic Foundation for Cancer Research, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece.
authors: Mattheos
authors: M
authors: Bobos
authors: Department of Medical Oncology, Ioannina University Hospital, Ioannina, Greece.
authors: George
authors: G
authors: Pentheroudakis
authors: Second Department of Medical Oncology, "Metropolitan" Hospital, Piraeus, Greece.
authors: Dimosthenis V
authors: DV
authors: Skarlos
authors: Oncology Section, Second Department of Internal Medicine, "Hippokration" Hospital, Athens, Greece.
authors: Dimitrios
authors: D
authors: Pectasides
authors: Laboratory of Molecular Oncology, Hellenic Foundation for Cancer Research, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece; Department of Pathology, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece.
authors: Vassiliki
authors: V
authors: Kotoula
authors: Laboratory of Molecular Oncology, Hellenic Foundation for Cancer Research, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece; Department of Medical Oncology, "Papageorgiou" Hospital, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece.
authors: George
authors: G
authors: Fountzilas
authors: Yale University, School of Medicine, Department of Pathology, New Haven, Connecticut, United States of America.
authors: David L
authors: DL
authors: Rimm
authors: Division of Oncology, Second Department of Internal Medicine, University of Athens School of Medicine, Attikon University Hospital, Athens, Greece.
authors: Amanda
authors: A
authors: Psyrri
mesh_terms: D000328:Adult; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use*; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D009362:Neoplasm Metastasis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D000068878:Trastuzumab; D016896:Treatment Outcome
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; C508053:ERBB2 protein, human