title: EGFR and EGFRvIII analysis in glioblastoma as therapeutic biomarkers.
abstract: BACKGROUND
  EGFR and EGFRvIII analysis is of current interest because of new EGFRvIII vaccine trials opened in the UK. EGFR activation promotes cellular proliferation via activation of MAPK and PI3K-Akt pathways. EGFRvIII is the most common variant resulting from an in-frame deletion of 801bp, leading to constitutively active EGFR.
  
  
  METHODS
  51 glioblastoma samples from a cohort of 50 patients were tested for EGFR amplification by FISH and immunohistochemistry and EGFRvIII expression by reverse-transcriptase PCR (RT-PCR), and immunohistochemistry. EGFR and EGFRvIII expression was compared with Overall Survival in the cohort.
  
  
  RESULTS
  Overall 22/51 samples (43%) were positive for EGFR, 16/51 (31%) were positive for EGFRvIII and 13/51 (25%) were positive for both. 9/51 cases (18%) were positive for EGFR alone, and 3/51 (6%) were positive for EGFRvIII alone. Of the EGFR positive cases, 22/51 (43%) were positive by FISH, 24/51 (47%) were positive by IHC and 2/51 (4%) were discrepant between methods (positive by IHC but non-amplified by FISH). Of the EGFRvIII positive cases, 16/51 (31%) were positive by RT-PCR, 17/51 (33%) were positive by IHC and 1/51 (2%) sample was discrepant (positive by IHC but not by RT-PCR). Neither EGFRvIII or EGFR are predictive of overall survival in this cohort.
  
  
  CONCLUSIONS
  In our cohort, 25/51 (49%) of GBM showed EGFR alterations, including 16/51 (31%) with EGFRvIII. There was high concordance between IHC and FISH (96%) and IHC and RT-PCR (98%) as diagnostic methods. Neither EGFR or EGFRvIII is predictive of overall survival in this cohort. These results are key for selecting patients for novel individualised anti-EGFR therapies.
authors.affiliation: a Bristol Genetics Laboratory, Southmead Hospital, North Bristol NHS Trust , Bristol , UK.
authors.forename: Claire
authors.initials: C
authors.lastname: Faulkner
authors.affiliation: a Bristol Genetics Laboratory, Southmead Hospital, North Bristol NHS Trust , Bristol , UK.
authors.forename: Abigail
authors.initials: A
authors.lastname: Palmer
authors.affiliation: b Department of Neuropathology , Brain Tumour Research Group, Frenchay Hospital, North Bristol NHS Trust Bristol , Bristol , UK.
authors.forename: Hannah
authors.initials: H
authors.lastname: Williams
authors.affiliation: a Bristol Genetics Laboratory, Southmead Hospital, North Bristol NHS Trust , Bristol , UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Wragg
authors.affiliation: b Department of Neuropathology , Brain Tumour Research Group, Frenchay Hospital, North Bristol NHS Trust Bristol , Bristol , UK.
authors.forename: Harry R
authors.initials: HR
authors.lastname: Haynes
authors.affiliation: d Department of Biostatistics , University of West of England , Bristol , UK.
authors.forename: Paul
authors.initials: P
authors.lastname: White
authors.affiliation: c Department of Neurosurgery , King's College Hospital , London , UK.
authors.forename: Ruth-Mary
authors.initials: RM
authors.lastname: DeSouza
authors.affiliation: a Bristol Genetics Laboratory, Southmead Hospital, North Bristol NHS Trust , Bristol , UK.
authors.forename: Maggie
authors.initials: M
authors.lastname: Williams
authors.affiliation: d Department of Biostatistics , University of West of England , Bristol , UK.|e Department of Neuro-oncology , Bristol Haematology and Oncology Centre , Bristol , UK.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Hopkins
authors.affiliation: b Department of Neuropathology , Brain Tumour Research Group, Frenchay Hospital, North Bristol NHS Trust Bristol , Bristol , UK.
authors.forename: Kathreena M
authors.initials: KM
authors.lastname: Kurian
keywords: epidermal growth factor receptor; glioblastoma; glioma