2P - Detection of treatment predictive biomarkers and genomic characterization of fixated circulating tumor cells (CTCs) in metastatic breast cancer

Date 04 May 2017
Event IMPAKT 2017
Session Welcome reception and Poster Walk
Topics Breast Cancer
Imaging, Diagnosis and Staging
Presenter Kristina Aaltonen
Authors K.E. Aaltonen1, C. Levin Tykjaer Jorgensen1, A. Ebbesson1, A. Larsson2, L. Rydén3
  • 1Department Of Clinical Sciences Lund - Oncology And Pathology, Lund University, 22381 - Lund/SE
  • 2Skåne Department Of Oncology, Skåne University Hospital, 22241 - Lund/SE
  • 3Department Of Surgery, Skåne University Hospital, 22241 - Lund/SE

Abstract

Body

The presence of circulating tumor cells (CTCs) in the blood of patients with breast cancer is by now a well-recognized prognosticator for poor prognosis but the selection of systemic therapy based on characteristics of CTCs is still under investigation. We present methods to characterize CTCs with respect to protein biomarker expression and genomic changes in individually selected CTCs.

Blood samples spiked with cell line cells (SKBr3, MCF7, BT474, Colo205) were used for method optimization and all applications were further validated in patient samples from the CTC-MBC study of metastatic breast cancer (Clinical Trials NCT01322893). CTCs were enriched with the FDA-approved CellSearch® system (Janssen Diagnostics) and subsequently fixated on glass slides using the CTC-DropMount method.

Here, we present additional applications for characterization of fixated CTCs. We have established a multiplex fluorescence staining procedure for detection of the established treatment predictive markers human epidermal growth factor receptor 2 (HER2) and estrogen receptor α (ERα), concurrent with positive and negative staining for CTCs according to a pre-defined evaluation protocol. In addition, we have now optimized fluorescence staining for programmed death-ligand 1 (PD-L1) expression on CTCs. This marker is suggested to be associated with response to immune checkpoint regulators. A protocol for HER2 gene amplification analysis has also been established using fluorescence in situ hybridization (FISH). Moreover, we have isolated individually selected CTCs using laser capture microdissection (PALM MicroBeam, Zeiss). Following whole genome amplification of the selected cells, the DNA quality suggests that a variety of genomic analyses could be employed to further characterize CTCs with regard to treatment predictive mutations, as well as to increase our understanding of tumor evolution.

CTCs are easily accessible in patient blood samples and could be used for further improvement of treatment selection as well as for monitoring treatment response. We have optimized methods to characterize CTCs following enrichment with the CellSearch® system.

Clinical trial identification

Verification of the methods presented in the abstract has been performed in patient samples from the CTC-MBC study (Clinical Trials NCT01322893).