26P - Whole exome sequencing of circulating and disseminated tumour cells in patients with metastatic breast cancer

Date 07 May 2015
Event IMPAKT 2015
Session Welcome reception and Poster Walk
Topics Breast Cancer, Metastatic
Translational Research
Presenter Dieter Peeters
Citation Annals of Oncology (2015) 26 (suppl_3): 10-14. 10.1093/annonc/mdv116
Authors D. Peeters1, A. Brouwer1, K. Op de Beeck2, G. Van de Weyer2, P. Pauwels3, M. Peeters3, P. Vermeulen1, S. Van Laere1, G. Van Camp2, L.Y. Dirix1
  • 1Center For Oncological Research, University of Antwerp, 2610 - Antwerp/BE
  • 2Center For Medical Genetics, University of Antwerp, Antwerp/BE
  • 3Center For Oncological Research, University of Antwerp, Antwerp/BE



Introduction: Circulating tumor cells (CTC) offer the potential to provide a repeatedly accessible source of tumor cells for the real-time assessment of tumor characteristics. This research focuses on evaluating the molecular heterogeneity within the CTC population and to what extent CTCs reflect mutational profiles in metastasis. Here, we report on the first results of a comparative study of mutation profiles of CTCs and synchronously isolated disseminated tumor cells (DTC) from metastatic sides of patients with clinically progressive MBC.

Methods: CTCs are isolated from 7.5 ml blood samples via enrichment by the CellSearch system and subsequent purification and sorting into several batches of 1-125 CTCs using the DEPArray system. DNA is isolated and amplified using the Ampli1 whole genome amplification kit and subjected to whole exome paired-end sequencing. DTCs from metastatic effusions, tissue from solid metastases or primary tumor, or bulk CTCs from patients having >10.000/7.5 ml (CellSearch Profile), are sequenced as a comparator for mutation profiles. Leukocyte DNA is sequenced to enable somatic mutation analysis.

Results: 8 samples of CTCs and a CellSearch Profile (patient 1) and 4 samples of CTC, 2 samples of DTC from a pleural effusion, and the primary tumor (patient 2) have been sequenced so far. Average base coverages were 13.6x (patient 1) and 11.8x (patient 2) for CTC/DTC samples, 175x for the CellSearch Profile, and 120x for the primary tumor sample. 29.6–53.6% of the exomes of amplified products were uncovered, probably due to technical limitations of the WGA procedure. Overall good concordances were observed for variants identified with MuTect in 28 frequently mutated genes between the CTC and the CellSearch Profile samples of patient 1. In patient 2, the same H1047R PIK3CA mutation was identified in the primary tumor and all CTC/DTC samples. In-depth analyses of the full exome data are being conducted and will be updated.

Disclosure: All authors have declared no conflicts of interest.