Abstract 3604: Centrosome amplification in epcam-captured circulating tumor cells from metastatic cancer patients

Abstract

Abstract Background: Genomic instability and evolution of cancers is linked to chemotherapy sensitivity and resistance in patients with metastatic cancer. Taxane-based chemotherapies operate by promoting chromosomal instability (CIN) by increasing multipolar mitoses. Breast tumors with CIN are more sensitive to paclitaxel compared to tumors without CIN. There is a critical need for new biomarkers based on biological evaluation of mechanisms of response and resistance in metastatic cancer. Although CIN is difficult to detect directly, centrosome amplification (CA) is a common mechanism of CIN. In this study, we develop an assay to detect CA in circulating tumor cells (CTCs) as a minimally invasive assay to evaluate sensitivity to taxane-based chemotherapies. Methods: Blood samples from patients with metastatic breast and prostate cancer were collected and processed for nucleated cells using a Ficoll gradient and magnetic depletion of CD45-positive cells. EpCAM-positive CTCs were captured using an exclusion-based sample preparation technology known as the VERSA (Versatile Exclusion-based Rare Sample Analysis) platform. CTCs were defined as cells positive for Hoechst, cytokeratin and negative for multiple immune and endothelial cell markers (CD45/CD11b/CD14 and CD34). EpCAM-captured CTCs were also stained with pericentrin and centrin to identify CA and evaluated for pericentrin (whole centrosome marker) and centrin (centriole marker) protein-staining intensity, number and size. Results: CA was detected in a subset of CTCs from patients with metastatic breast and prostate cancer patients. As a control, centrosomes were also analyzed in matched peripheral blood mononuclear cells from the same patients. CA was heterogeneous with 100% of patients demonstrating some degree of CA (>4 centrioles), ranging from 15-48% of CTCs. Conclusion: In conclusion, we report the presence of CA in EpCAM-captured CTCs from metastatic cancer patients. Evaluation of CA in CTCs using pericentrin and centrin staining may serve as a predictive biomarker of taxane based chemotherapy response and resistance. We are recruiting taxane-naïve metastatic cancer patients to test the hypothesis that CA and/or CIN predict taxane sensitivity. Citation Format: Ashok Singh, Ryan A. Denu, Jamie M. Sperger, Beth A. Weaver, Mark E. Burkard, Joshua M. Lang. Centrosome amplification in epcam-captured circulating tumor cells from metastatic cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3604.