25P - Detection of HER2-status and genomic analysis of disseminated cancer cells (DCCs) of non-metastatic breast cancer patients with HER2-negative and po...

Date 07 May 2015
Event IMPAKT 2015
Session Welcome reception and Poster Walk
Topics Breast Cancer, Early Stage
Translational Research
Presenter Elisabeth Doblinger
Citation Annals of Oncology (2015) 26 (suppl_3): 10-14. 10.1093/annonc/mdv116
Authors E. Doblinger1, O. Schmidt2, Z. Czyz3, G. Haunschild2, B. Rack4, T. Schamberger2, C. Klein2
  • 1Experimental Medicine And Therapy Research, University of Regensburg, 93053 - Regensburg/DE
  • 2Experimental Medicine And Therapy Research, University of Regensburg, Regensburg/DE
  • 3Personalized Tumor Therapy, Fraunhofer Institute for Toxicology and Experimental Medicine (ITEM-R), Regensburg/DE
  • 4Department Of Gynecology And Obstretrics, LMU Klinikum der Universität München, München/DE

Abstract

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Background: HER2 amplification defines a very aggressive breast cancer subtype, which is treated with HER2-targeting therapies. HER2 amplifications are assessed on primary tumors, which are used as surrogate marker for the HER2 status of disseminated cancer cells (DCCs), the target cells of anti-HER2-directed therapies. Protein expression studies on DCCs as well as fluorescence in situ hybridization studies indicated that primary tumors and DCCs might be disparate for HER2 amplification. We developed a novel quantitative real-time PCR (qPCR) method following Ampli1TM single cell whole genome amplification (WGA) and determined the HER2-status of DCCs from breast cancer patients with HER2-negative and HER2-positive primary tumors.

Patients and methods: We investigated 56 breast cancer patients without evidence of metastasis, of whom we had successfully isolated 85 cytokeratin-positive cells from bone marrow. Forty-five patients (n= 70 cells) had HER2-negative and 11 patients (n= 15 cells) HER2-positive primary tumors. The DNA of isolated DCCs was amplified using the Ampli1TM WGA kit. HER2 amplification was assessed by qPCR. Selected DCCs were subsequently analyzed for genome-wide copy number alterations.

Results: Seven HER2-positive DCCs isolated from 7 patients were detected in 38 patients with HER2-negative primary tumors. Therefore, disparity for HER2 status was 18%. We detected only one HER2-positive DCC among 9 patients with HER2-positive primary tumors, translating into a disparity rate of 89%. In all cases with HER2-positive DCCs, additional DCCs were Her2-negative. Interestingly, upon comparative genomic hybridization analysis, we found that HER2-positive DCCs displayed only few and small losses and gains.

Conclusion: In summary, the disparity rate for HER2-status between DCCs and their HER2-positive primary tumors is higher than between DCCs and their HER2-negative primary tumors. However, as HER2-positive DCCs displayed rather few and small genomic alterations, we conclude that HER2 amplification is an early but not initiating event in the genomic evolution of these cells.

Disclosure: All authors have declared no conflicts of interest.