Abstract 6439: CapioCyte™ technology for efficient capture and downstream analysis of circulating tumor cells from renal cell carcinoma
Authors: Jiyoon Bu, Michael J. Poellmann, Marco Reyes-Martinez, Andrew Armstrong, Daniel George, Tian Zhang, Andrew Z. Wang, seungpyo hong
Journal: Cancer Research (2020)

Abstract Objective: The objective of this work was to obtain highly sensitive purification and post-capture analysis of renal cell carcinoma (RCC) circulating tumor cells (CTCs) using CapioCyte™ technology. Background: Circulating tumor cells (CTCs) may be a highly valuable source of actionable information for the practice of precision medicine. However, CTCs are exceptionally rare in peripheral blood. The CapioCyte™ chip purifies live CTCs through a combination of biomimetic cell rolling and dendrimer-mediated multivalent immunorecognition. The CapioCyte™ platform has been previously shown to isolate CTCs with high sensitivity from peripheral blood collected from patients with head and neck cancer using a mixture of antibodies against epithelial cell adhesion molecule (EpCAM), human epidermal growth factor receptor 2 (HER2), and epidermal growth factor receptor (EGFR) [Myung et al., Clinical Cancer Research 2018, 24(11):2539-2547]. However, this antibody cocktail is not universally applicable to all types of cancer. In particular, renal cell carcinoma (RCC), having no clinically actionable circulating biomarkers, often do not express HER2. To address this, we have employed a new antibody mixture targeting EpCAM, EGFR, carbonic anhydrase IX (CAIX), and hepatocyte growth factor receptor (c-MET). Our study presents enhanced capture of CTCs from renal cancer, demonstrating the modular nature of our CapioCyte™ technology. Methods: Antibody-coated beads were used to determine the functional recognition of ACHN and 786-O RCC cell lines. Flow channel experiments and atomic force microscopy (AFM) force spectroscopy measurements were used to quantify off-rate kinetics. A clinical pilot study of 7 RCC patients (pre-treatment) and 5 healthy controls was performed to validate the CapioCyte™ surface tuned for RCC capture. In recent work, CTCs recovered from the CapioCyte™ surface were sequenced using 10X Chromium system with v3 chemistry and analyzed using RaceID clustering and Gene Set Enrichment Analysis (GSEA). Results: The optimized mixture of EpCAM, CAIX, EGFR, and c-MET showed 80% enhancement in the capture of RCC cell lines compared to the mixture of EpCAM, EGFR, and HER2. Force spectroscopy measurements were used to show that dendrimers contributed to an order of magnitude enhancement in off-rate kinetics. In patient samples, the RCC capture surface isolated a total of 9.8 +/- 5.1 CTC ml-1 whole blood compared to just 1.8 +/- 2.0 CTC ml-1 with the conventional three-antibody mixture. Finally, preliminary results show the detection of oncogenic signatures within two additional peripheral blood samples. Conclusions: The prototype CapioCyte™ platform is a flexible liquid biopsy that can be tuned for various disease indications. Here, enhanced capture of RCC CTCs was demonstrated in clinical blood samples with high sensitivity. Proof-of-concept RNA sequencing shows the promise of CapioCyte™ in providing further clinically-actionable information from CTCs. Citation Format: Jiyoon Bu, Michael J. Poellmann, Marco Reyes-Martinez, Andrew Armstrong, Daniel George, Tian Zhang, Andrew Z. Wang, seungpyo hong. CapioCyte™ technology for efficient capture and downstream analysis of circulating tumor cells from renal cell carcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6439.