Abstract 669: Quantification of estrogen (ER) and progestin receptor (PR) as well as HER2/neu proteins and gene expression improves discrimination of clinical behavior by triple positive breast carcinomas
Authors: Hameed Zohair R. , Daniels Michael W. , Kerr D. Alan , Wittliff James L. 
Published: July 2017

IHC analyses of ER, PR and HER2 proteins are used as clinical biomarkers for breast cancer management. However, IHC provides semi-quantitative results sometimes complicated by variation in methods and interpretation. Our goal was to ascertain clinical use of these three analytes to predict breast cancer recurrence when analyses for gene expression and protein products were quantified.

Procedures: We examined ER and PR protein in 1059 de-identified carcinoma biopsies previously quantified by radio-ligand binding and/or enzyme immunoassay (EIA) using FDA approved reagents and HER2 oncoprotein determined by EIA to assess relationships between biomarker profiles and disease-free (DFS) and overall survival (OS) for 123 patients. Our comprehensive, IRB-approved Database also contained de-identified Microarray results obtained for ~ 22,000 genes from LCM-procured breast carcinoma cells of 247 primary breast biopsies. ESR1, PGR and ERBB2 gene expression levels were validated previously in 278 cancers by qPCR.

Results: Generalized Pair Plots of the three protein biomarkers indicated a relationship only between ER and PR supporting evidence that ER complexed with estrogenic ligands promotes synthesis of PR. Of the 8 possible combinations of the 3 protein biomarkers, only breast cancers exhibiting ER+PR+HER2+ (triple positive breast cancer, TPBCa) exhibited increased OS, whereas those with triple negative breast cancers (TNBCa) had decreased OS. TPBCa was exhibited by 32.5 % of specimens compared to TNBCa, which represented 7.3% of biopsies when biomarker proteins were quantified. Number of TPBCa was less when expression of the 3 genes (ESR1+/PGR+/ERBB2+) was measured by microarray or by qPCR while those of TNBCa increased. Furthermore, when TPBCa were identified by either microarray or by qPCR measurements, collectively increased ESR1, PGR and ERBB2 expression was associated with increased PFS and OS of patients. In contrast, biopsies that were ESR1-/PGR-/ERBB+ (14.1%) correlated with poor prognosis and overall survival using qPCR data, while those exhibiting ESR1-PGR+ERBB2- (14.1%) profiles by microarray results exhibited decreased PFS and OS. Influence of patient menopausal status on biomarker profiles was examined.

Conclusions: Quantitative measurements of ER, PR and HER2 proteins as well as microarray and qPCR assessment of ESR1, PGR and ERBB2 gene expression were correlated with prediction of clinical outcomes of breast carcinomas exhibiting Triple Positive Breast Cancers (TPBCa). Results reinforce importance of assessing levels of the three biomarkers in a quantified fashion to enhance their use in breast cancer management and prediction of risk of recurrence.

Citation Format: Zohair R. Hameed, Michael W. Daniels, D. Alan Kerr, James L. Wittliff. Quantification of estrogen (ER) and progestin receptor (PR) as well as HER2/neu proteins and gene expression improves discrimination of clinical behavior by triple positive breast carcinomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 669. doi:10.1158/1538-7445.AM2017-669