title: High HER2 protein levels correlate with increased survival in breast cancer patients treated with anti-HER2 therapy.
abstract: BACKGROUND
  Current methods to determine HER2 (human epidermal growth factor receptor 2) status are affected by reproducibility issues and do not reliably predict benefit from anti-HER2 therapy. Quantitative measurement of HER2 may more accurately identify breast cancer (BC) patients who will respond to anti-HER2 treatments.
  
  
  METHODS
  Using selected reaction monitoring mass spectrometry (SRM-MS), we quantified HER2 protein levels in formalin-fixed, paraffin-embedded (FFPE) tissue samples that had been classified as HER2 0, 1+, 2+ or 3+ by immunohistochemistry (IHC). Receiver operator curve (ROC) analysis was conducted to obtain optimal HER2 protein expression thresholds predictive of HER2 status (by standard IHC or in situ hybridization [ISH]) and of survival benefit after anti-HER2 therapy.
  
  
  RESULTS
  Absolute HER2 amol/μg levels were significantly correlated with both HER2 IHC and amplification status by ISH (p < 0.0001). A HER2 threshold of 740 amol/μg showed an agreement rate of 94% with IHC and ISH standard HER2 testing (p < 0.0001). Discordant cases (SRM-MS-negative/ISH-positive) showed a characteristic amplification pattern known as double minutes. HER2 levels >2200 amol/μg were significantly associated with longer disease-free survival (DFS) and overall survival (OS) in an adjuvant setting and with longer OS in a metastatic setting.
  
  
  CONCLUSIONS
  Quantitative HER2 measurement by SRM-MS is superior to IHC and ISH in predicting outcome after treatment with anti-HER2 therapy.
authors.affiliation: Molecular Oncology Laboratory, Vall d'Hebron Institute of Oncology, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain.|Universitat Autònoma de Barcelona, Plaça Cívica, 08193 Bellaterra (Cerdanyola del Vallès), Spain.
authors.forename: Paolo
authors.initials: P
authors.lastname: Nuciforo
authors.affiliation: OncoPlex Diagnostics (Division of NantOmics, LLC), 9600 Medical Center Drive, Suite 300, Rockville, MD 20850, USA.
authors.forename: Sheeno
authors.initials: S
authors.lastname: Thyparambil
authors.affiliation: Molecular Oncology Laboratory, Vall d'Hebron Institute of Oncology, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain.
authors.forename: Claudia
authors.initials: C
authors.lastname: Aura
authors.affiliation: Department of Oncology, Vall d'Hebron University Hospital, Vall d'Hebron Institute of Oncology, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Garrido-Castro
authors.affiliation: Molecular Oncology Laboratory, Vall d'Hebron Institute of Oncology, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Vilaro
authors.affiliation: Department of Pathology, Vall d'Hebron University Hospital, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain.
authors.forename: Vicente
authors.initials: V
authors.lastname: Peg
authors.affiliation: Molecular Oncology Laboratory, Vall d'Hebron Institute of Oncology, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Jimenez
authors.affiliation: Preclinical Research Program, Vall d'Hebron Institute of Oncology, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain.
authors.forename: Rocio
authors.initials: R
authors.lastname: Vicario
authors.affiliation: OncoPlex Diagnostics (Division of NantOmics, LLC), 9600 Medical Center Drive, Suite 300, Rockville, MD 20850, USA.
authors.forename: Fabiola
authors.initials: F
authors.lastname: Cecchi
authors.affiliation: OncoPlex Diagnostics (Division of NantOmics, LLC), 9600 Medical Center Drive, Suite 300, Rockville, MD 20850, USA.
authors.forename: William
authors.initials: W
authors.lastname: Hoos
authors.affiliation: OncoPlex Diagnostics (Division of NantOmics, LLC), 9600 Medical Center Drive, Suite 300, Rockville, MD 20850, USA.
authors.forename: Jon
authors.initials: J
authors.lastname: Burrows
authors.affiliation: OncoPlex Diagnostics (Division of NantOmics, LLC), 9600 Medical Center Drive, Suite 300, Rockville, MD 20850, USA.
authors.forename: Todd
authors.initials: T
authors.lastname: Hembrough
authors.affiliation: Department of Pathology, Vall d'Hebron University Hospital, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain.
authors.forename: Juan Carles
authors.initials: JC
authors.lastname: Ferreres
authors.affiliation: Department of Oncology, Vall d'Hebron University Hospital, Vall d'Hebron Institute of Oncology, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Perez-Garcia
authors.affiliation: Preclinical Research Program, Vall d'Hebron Institute of Oncology, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain.|Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain.
authors.forename: Joaquin
authors.initials: J
authors.lastname: Arribas
authors.affiliation: Department of Oncology, Vall d'Hebron University Hospital, Vall d'Hebron Institute of Oncology, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Cortes
authors.affiliation: Human Oncology & Pathogenesis Program (HOPP), Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, Box 20, New York, NY 10065, USA.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Scaltriti
mesh_terms: D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D005260:Female; D006801:Humans; D000077341:Lapatinib; D013058:Mass Spectrometry; D011799:Quinazolines / Q000627:therapeutic use; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016019:Survival Analysis; D000068878:Trastuzumab / Q000627:therapeutic use
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D000077341:Lapatinib; D011799:Quinazolines; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; C508053:ERBB2 protein, human; C485206:pertuzumab
keywords: Breast cancer; HER2; Immunohistochemistry; In situ hybridization; Mass spectrometry; Trastuzumab