Circulating Tumor Cell Analysis in Preclinical Mouse Models of Metastasis

Abstract

The majority of cancer deaths occur because of metastasis since current therapies are largely non-curative in the metastatic setting. The use of in vivo preclinical mouse models for assessing metastasis is, therefore, critical for developing effective new cancer biomarkers and therapies. Although a number of quantitative tools have been previously developed to study in vivo metastasis, the detection and quantification of rare metastatic events has remained challenging. This review will discuss the use of circulating tumor cell (CTC) analysis as an effective means of tracking and characterizing metastatic disease progression in preclinical mouse models of breast and prostate cancer and the resulting lessons learned about CTC and metastasis biology. We will also discuss how the use of clinically-relevant CTC technologies such as the CellSearch® and Parsortix™ platforms for preclinical CTC studies can serve to enhance the study of cancer biology, new biomarkers, and novel therapies from the bench to the bedside.

Lysyl Oxidase Like‐2 (LOXL2): An Emerging Oncology Target

“…This was further supported by circulating tumor cell (CTC) analysis, which showed a positive correlation between LOXL2 expression and CTCs. The knockout mice to have the least amount of CTC followed by the control, and then the LOXL2 over‐expressing mice, which had the greatest number of CTC, indicating a high potential for metastases . These results indicate that LOXL2 plays a vital role in metastasis to the lung in this model, in agreement with earlier findings …”

“…The knockout mice to have the least amount of CTC followed by the control, and then the LOXL2 over-expressing mice, which had the greatest number of CTC, indicating a high potential for metastases. [38,81] These results indicate that LOXL2 plays a vital role in metas-tasis to the lung in this model, in agreement with earlier findings. [55] Multiple reports have shown that MMP's and LOXL2 interplay to facilitate invasion.…”

Review of emerging biomarkers in head and neck squamous cell carcinoma in the era of immunotherapy and targeted therapy

“…Several important advances have been achieved in recent years, that have improved the potential of liquid biopsy markers as robust clinical tools. Such advances include (a) estimation of tumor mutational burden through evaluation of plasma cfDNA 200 ; (b) more therapy-directed applications of CTCs, for example, PD-L1 expression in CTCs 163,165,182 ; (c) use of CTCs as a longitudinal monitoring tool to detect minimal residual disease after curative surgery 171 ; (d) CTC-derived xenografts used as surrogates to study tumor biology [201][202][203] ; and (e) three-dimensional CTC cultures 204 and CTC-derived organoids to aid in individualized precision medicine. 205…”

The Parsortix™ Cell Separation System—A versatile liquid biopsy platform

“…Cell viability ensures integrity of nucleic acids, allowing molecular interrogation of the harvests with both increased sensitivity of detection (concentration effect) and decreased background (enrichment effect). The Parsortix System has been used to successfully capture and/or harvest CTCs from a number of different cancer types, with the harvested CTCs successfully evaluated by a variety of subsequent analysis techniques, including: cytological/histological staining and/or immunostaining for identification, enumeration and detection of protein biomarkers on captured and/or harvested CTCs (Figure B,C) ; individual gene expression (mRNA) analysis (e.g., ddPCR and qPCR) ; multiplex nucleic acid or protein evaluation (e.g., via Ziplex® System Flow‐Thru Chip® technology [ANGLE Biosciences, Toronto, CA]); evaluation of DNA aberrations (e.g., aCGH and HER2 FISH) ; whole transcriptome or genome sequencing (e.g., RNA‐seq and DNA‐seq) ; mouse xenograph models . …”

“…The typical rate of separation for whole blood on the system is approximately 5 ml/h. The Parsortix System allows for the harvest of the captured cells from the separation cassette into a small volume (100–210 μl) of buffer, such as PBS, enabling a high level of versatility in how the cells could be evaluated and/or clinically interrogated .…”