Abstract 5590: MiSelect R: A novel single-cell retrieval system for CTC from whole blood for biomarker analysis in cancer targeted and immunotherapy
Authors: Tseng Ju-Yu , Chen Yen-Ru , Lee Chia-Ying , Wu Li-Fan , Wang Cheng-Hsu , Wang Shin-Hang , Yu Hui-Min , Fang Wei-Feng , Chen Mu-Yi , Chen Chwen-Cheng 
Published: August 2018

Background: Circulating tumor cells' (CTCs) presence in patient's peripheral circulation has been recognized as a useful tool of liquid biopsy for cancer treatment. In addition to enumeration, analysis of associated protein and molecular alterations offers great potential for precision medicine. MiSelect R was invented for purification and characterization of rare cells including CTC. This study evaluates MiSelect R analytic performances and validates with clinical samples.

Methods: Lung cancer cell line H2228 was spiked into 8 mL of whole blood (16 cells/ 8mL) for single-cell retrieval, subsequent RT-PCR and sequencing analysis on ALK-translocation. Breast cancer cell lines, SKBr3 (high EpCAM expressing) and MDA-MB-231 (low EpCAM expressing), were spiked into 8mL whole blood from healthy subjects at various concentrations (4-1024 cells/ 8mL) for recovery rate and linearity. Experiments with low cell spikes (32 cells/ 8mL) vs. high cell spikes (1024 cells/ 8mL) were carried out to assess the within-device precision. The assay specificity was examined in blood of healthy subjects. Further evaluation was performed in metastatic breast cancer (mBC) patients.

Results: Spiked H2228 cells were retrieved with greater than 90% recovery rate and 70% purity from whole blood. Each retrieved single H2228 cell was confirmed to have ALK-EML4 translocation by RT-PCR and sequencing analysis. The detection ranges of 4 to 1024 SkBr3 and MDA-MB-231 cells per 8mL were confirmed to be linear with average recovery rate of 91% (R2 = 0.9949) and 70% (R2 = 0.9983), respectively. The within-device precision showed 9.23% and 7.82% CV for low cell spikes vs. high cell spikes. Great assay specificity was achieved with no CTC detected in healthy subjects (N = 42). 100% detection rate of CTC was achieved in untreated mBC patients and 47% for patients regardless of treatment history. Also, the HER2 score analyzed by MiSelect R in isolated CTCs was in agreement with that by IHC analysis. Nonetheless, the HER2 expression level was heterogeneous in the CTCs isolated from HER2-positive patients. Furthermore, the PD-L1 expression in CTCs was shown to be heterogeneous within and between cancer patients.

Conclusion: The MiSelect R System showed excellent capability for single-cell retrieval of rare cells from whole blood. It also demonstrated outstanding analytic performances and clinical sensitivity for CTC detection as well as versatile capability for multiple-biomarker characterization. It potentially provides important cellular and molecular information at single-cell level from liquid biopsy for prognosis.

Citation Format: Ju-Yu Tseng, Yen-Ru Chen, Chia-Ying Lee, Li-Fan Wu, Cheng-Hsu Wang, Shin-Hang Wang, Hui-Min Yu, Wei-Feng Fang, Mu-Yi Chen, Chwen-Cheng Chen. MiSelect R: A novel single-cell retrieval system for CTC from whole blood for biomarker analysis in cancer targeted and immunotherapy [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 5590.