Mass-spectrometry-based quantitation of Her2 in gastroesophageal tumor tissue: comparison to IHC and FISH.
Gastric Cancer
; 19(4): 1066-1079, 2016 Oct.
Article
in En
| MEDLINE
| ID: mdl-26581548
ABSTRACT
BACKGROUND:
Trastuzumab has shown a survival benefit in cases of Her2-positive gastroesophageal cancer (GEC). Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) currently determine eligibility for trastuzumab-based therapy. However, these low-throughput assays often produce discordant or equivocal results.METHODS:
We developed a targeted proteomic assay based on selected reaction monitoring mass spectrometry (SRM-MS) and quantified levels (amol/µg) of Her2-SRM protein in cell lines (n = 27) and GEC tissues (n = 139). We compared Her2-SRM protein expression with IHC/FISH, seeking to determine optimal SRM protein expression cutoffs in order to identify HER2 gene amplification.RESULTS:
After demonstrating assay development, precision, and stability, Her2-SRM protein measurement was observed to be highly concordant with the HER2/CEP17 ratio, particularly in a multivariate regression model adjusted for SRM expression of the covariates Met, Egfr, Her3, and HER2 heterogeneity, as well as their interactions (cell lines r (2) = 0.9842; FFPE r (2) = 0.7643). In GEC tissues, Her2-SRM protein was detected at any level in 71.2 % of cases. ROC curves demonstrated that Her2-SRM protein levels have a high specificity (100 %) at an upper-level cutoff of >750 amol/µg and sensitivity of 75 % at a lower-level cutoff of <450 amol/µg for identifying HER2 FISH-amplified tumors. An "equivocal zone" of 450-750 amol/µg of Her2-SRM protein was analogous to IHC2+ but represented fewer cases (9-16 % of cases versus 36-41 %).CONCLUSIONS:
Compared to IHC, targeted SRM-Her2 proteomics provided more objective and quantitative Her2 expression with excellent HER2/CEP17 FISH correlation and fewer equivocal cases. Along with its multiplex capability for other relevant oncoproteins, these results demonstrate a refined HER2 protein expression assay for clinical application.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Stomach Neoplasms
/
In Situ Hybridization, Fluorescence
/
Receptor, ErbB-2
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Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
/
Proteomics
Limits:
Humans
Language:
En
Journal:
Gastric Cancer
Journal subject:
GASTROENTEROLOGIA
/
NEOPLASIAS
Year:
2016
Document type:
Article
Affiliation country: