Cytometric comparisons between circulating tumor cells from prostate cancer patients and the prostate-tumor-derived LNCaP cell line

Agent-based modeling of the prostate tumor microenvironment uncovers spatial tumor growth constraints and immunomodulatory properties

Inhibiting androgen receptor (AR) signaling through androgen deprivation therapy (ADT) reduces prostate cancer (PCa) growth in virtually all patients, but response may be temporary, in which case resistance develops, ultimately leading to lethal castration-resistant prostate cancer (CRPC). The tumor microenvironment (TME) plays an important role in the development and progression of PCa. In addition to tumor cells, TME-resident macrophages and fibroblasts express AR and are therefore also affected by ADT. However, the interplay of different TME cell types in the development of CRPC remains largely unexplored. To understand the complex stochastic nature of cell-cell interactions, we created a PCa-specific agent-based model (PCABM) based on in vitro cell proliferation data. PCa cells, fibroblasts, "pro-inflammatory" M1-like and "pro-tumor" M2-like polarized macrophages are modeled as agents from a simple set of validated base assumptions. PCABM allows us to simulate the effect of ADT on the interplay between various prostate TME cell types. The resulting in vitro growth patterns mimic human PCa. Our PCABM can effectively model hormonal perturbations by ADT, in which PCABM suggests that CRPC arises in clusters of resistant cells, as is observed in multifocal PCa. In addition, fibroblasts compete for cellular space in the TME while simultaneously creating niches for tumor cells to proliferate in. Finally, PCABM predicts that ADT has immunomodulatory effects on macrophages that may enhance tumor survival. Taken together, these results suggest that AR plays a critical role in the cellular interplay and stochastic interactions in the TME that influence tumor cell behavior and CRPC development.

Exploring the Onset and Progression of Prostate Cancer through a Multicellular Agent-based Model

Over 10% of men will be diagnosed with prostate cancer during their lifetime. Arising from luminal cells of the prostatic acinus, prostate cancer is influenced by multiple cells in its microenvironment. To expand our knowledge and explore means to prevent and treat the disease, it is important to understand what drives the onset and early stages of prostate cancer. In this study, we developed an agent-based model of a prostatic acinus including its microenvironment, to allow for in silico studying of prostate cancer development. The model was based on prior reports and in-house data of tumor cells cocultured with cancer-associated fibroblasts (CAF) and protumor and/or antitumor macrophages. Growth patterns depicted by the model were pathologically validated on hematoxylin and eosin slide images of human prostate cancer specimens. We identified that stochasticity of interactions between macrophages and tumor cells at early stages strongly affect tumor development. In addition, we discovered that more systematic deviations in tumor development result from a combinatorial effect of the probability of acquiring mutations and the tumor-promoting abilities of CAFs and macrophages. In silico modeled tumors were then compared with 494 patients with cancer with matching characteristics, showing strong association between predicted tumor load and patients' clinical outcome. Our findings suggest that the likelihood of tumor formation depends on a combination of stochastic events and systematic characteristics. While stochasticity cannot be controlled, information on systematic effects may aid the development of prevention strategies tailored to the molecular characteristics of an individual patient.

Significance

We developed a computational model to study which factors of the tumor microenvironment drive prostate cancer development, with potential to aid the development of new prevention strategies.

Zhoushi Qiling decoction inhibits proliferation of human prostate cancer cells through IL6/STAT3 pathway

Background: Prostate cancer is the most common malignant tumor in men, accounting for one of the top five cancer incidences worldwide. However, there is no effective pharmacological treatment for advanced prostate cancer (APC). Herein, we aim to investigate the mechanism of Zhoushi Qiling decoction (ZQD), a traditional Chinese medicine compound, in inhibiting prostate cancer cells proliferation and tumor growth. Methods: IC50 was determined in PC3 and DU145 cells. Cell viability was determined using MTT assay after interleukin (IL) 6 stimulation. Cell proliferation ability was evaluated using colony formation assay. IL-6/signal transducer and activator of transcription 3 (STAT3) signaling pathway was analyzed using qRT-PCR and Western blot in PC3 and DU145 cells and xenograft tumor tissues. Results: It was found that ZQD significantly inhibited Il-6-induced cell viability and proliferation in PC3 and DU145 cells. Moreover, ZQD significantly reduced mRNA levels of IL-6, IL-1β, STAT3, Bcl2, and CyclinD1, stimulated by IL-6. The protein levels of p-STAT3, Bcl2 and CyclinD1 were reduced by ZQD treatment at 40 mg/mL both in PC3 and DU145 cells. Additionally, in xenograft tumor tissues, tumor volume, weight and proliferation were significantly reduced by ZQD treatment. In addition, the mRNA and protein levels of IL-6 and pSTAT3 were significantly inhibited by ZQD treatment in vivo. Conclusion: We demonstrate that ZQD can effectively reduce cell proliferation and tumor growth by inhibiting the activation of IL-6/STAT3 signaling pathway.

Measuring antigen expression of cancer cell lines and circulating tumour cells

When evaluating EpCAM-based enrichment technologies for circulating tumour cells (CTCs), the cell lines used should closely resemble real CTCs, meaning the EpCAM expression of CTCs needs to be known, but also the EpCAM expression of cell lines at different institutions and times is important. As the number of CTCs in the blood is low, we enriched CTCs through the depletion of leukocytes from diagnostic leukapheresis products of 13 prostate cancer patients and measured EpCAM expression using quantitative flow cytometry. Antigen expression was compared between multiple institutions by measuring cultures from each institution. Capture efficiency was also measured for one of the used cell lines. Results show CTCs derived from castration-sensitive prostate cancer patients have varying but relatively low EpCAM expression, with median expression per patient ranging from 35 to 89,534 (mean 24,993) molecules per cell. A large variation in the antigen expression of identical cell lines cultured at different institutions was found, resulting in recoveries when using the CellSearch system ranging from 12 up to 83% for the same cell line. We conclude that large differences in capture efficiency can occur while using the same cell line. To closely resemble real CTCs from castration-sensitive prostate cancer patients, a cell line with a relatively low EpCAM expression should be used, and its expression should be monitored frequently.

Unraveling Cancer Metastatic Cascade Using Microfluidics-based Technologies

Cancer has long been a leading cause of death. The primary tumor, however, is not the main cause of death in more than 90% of cases. It is the complex process of metastasis that makes cancer deadly. The invasion metastasis cascade is the multi-step biological process of cancer cell dissemination to distant organ sites and adaptation to the new microenvironment site. Unraveling the metastasis process can provide great insight into cancer death prevention or even treatment. Microfluidics is a promising platform, that provides a wide range of applications in metastasis-related investigations. Cell culture microfluidic technologies for in vitro modeling of cancer tissues with fluid flow and the presence of mechanical factors have led to the organ-on-a-chip platforms. Moreover, microfluidic systems have also been exploited for capturing and characterization of circulating tumor cells (CTCs) that provide crucial information on the metastatic behavior of a tumor. We present a comprehensive review of the recent developments in the application of microfluidics-based systems for analysis and understanding of the metastasis cascade from a wider perspective.

A new insight to deformability correlation of circulating tumor cells with metastatic behavior by application of a new deformability-based microfluidic chip

Isolation and characterization of circulating tumor cells (CTCs) found in blood samples of cancer patients have been considered as a reliable source for cancer prognosis and diagnosis. A new continuous microfluidic platform has been designed in this investigation for simultaneous capture and characterization of CTCs based on their deformability. The deformability-based chip (D-Chip) consists of two sections of separation and characterization where slanted weirs with a gap of 7 μm were considered. Although sometimes CTCs and leukocytes have the same size, the deformability differs in such a way that can be exploited for enrichment purposes. MCF7 and MDA-MB-231 cell lines were used for the initial evaluation of the D-Chip performance. In the separation section, cancer cells were isolated based on deformability differences with an efficiency of higher than 93% (∼average capturing capacity of 2085 out of 2200 cancer cells ml^-1) and with significantly high purity (15-40 WBCs ml^-1; ∼5 log depletion of WBCs). Cancer cells were categorized based on the deformability difference in the characterization section. Subsequently, 15 clinical blood samples from breast cancer patients were analyzed by the D-Chip. Suggest 'The chip detected CTCs in all patient samples, processed the blood sample at a high throughput of 5.3 ml/h, and properly categorized CTCs based on deformability differences. Further characterization showed that the highly deformable breast cancer CTCs in our patient samples also showed higher potential of metastasis in support of a broader correlation between deformability of CTCs and metastatic behavior.

Short-Term Ex Vivo Culture of CTCs from Advance Breast Cancer Patients: Clinical Implications

Simple Summary

Circulating tumor cells (CTCs) are responsible for metastasis, they represent tumor biology and have also predictive value for therapy monitoring and prognosis of metastatic breast cancer patients. In the blood, CTCs are found in low frequency and a small percentage of them survive. Therefore, achieving their expansion in vitro will allow performing characterization and functional analysis. In this work, we used growth factors and Nanoemulsions to support CTCs culture. We have seen that the CTCs subpopulation capable of ex vivo expanding presented mesenchymal and stem characteristics and loss of epithelial markers. Besides, CTC culture predicted progression-free survival.

Abstract

Background: Circulating tumor cells (CTC) have relevance as prognostic markers in breast cancer. However, the functional properties of CTCs or their molecular characterization have not been well-studied. Experimental models indicate that only a few cells can survive in the circulation and eventually metastasize. Thus, it is essential to identify these surviving cells capable of forming such metastases. Methods: We isolated viable CTCs from 50 peripheral blood samples obtained from 35 patients with advanced metastatic breast cancer using RosetteSep^TM for ex vivo culture. The CTCs were seeded and monitored on plates under low adherence conditions and with media supplemented with growth factors and Nanoemulsions. Phenotypic analysis was performed by immunofluorescence and gene expression analysis using RT-PCR and CTCs counting by the Cellsearch^® system. Results: We found that in 75% of samples the CTC cultures lasted more than 23 days, predicting a shorter Progression-Free Survival in these patients, independently of having ≥5 CTC by Cellsearch^®. We also observed that CTCs before and after culture showed a different gene expression profile. Conclusions: the cultivability of CTCs is a predictive factor. Furthermore, the subset of cells capable of growing ex vivo show stem or mesenchymal features and may represent the CTC population with metastatic potential in vivo.

Circulating Tumor Cells: High-Throughput Imaging of CTCs and Bioinformatic Analysis

Circulating tumor cells (CTCs) represent novel biomarkers, since they are obtainable through a simple and noninvasive blood draw or liquid biopsy. Here, we review the high-definition single-cell analysis (HD-SCA) workflow, which brings together modern methods of immunofluorescence with more sophisticated image processing to rapidly and accurately detect rare tumor cells among the milieu of platelets, erythrocytes, and leukocytes in the peripheral blood. In particular, we discuss progress in methods to measure CTC morphology and subcellular protein expression, and we highlight some initial applications that lead to fundamental new insights about the hematogenous phase of cancer, as well as its performance in early-stage diagnosis and treatment monitoring. We end with an outlook on how to further probe CTCs and the unique advantages of the HD-SCA workflow for improving the precision of cancer care.

Targets, pitfalls and reference materials for liquid biopsy tests in cancer diagnostics

Assessment of cell free DNA (cfDNA) and RNA (cfRNA), circulating tumor cells (CTC) and extracellular vesicles (EV) in blood or other bodily fluids can enable early cancer detection, tumor dynamics assessment, minimal residual disease detection and therapy monitoring. However, few liquid biopsy tests progress towards clinical application because results are often discordant and challenging to reproduce. Reproducibility can be enhanced by the development and implementation of standard operating procedures and reference materials to identify and correct for pre-analytical variables. In this review we elaborate on the technological considerations, pre-analytical variables and the use and availability of reference materials for the assessment of liquid biopsy targets in blood and highlight initiatives towards the standardization of liquid biopsy testing.

Androgen receptor nuclear localization correlates with AR-V7 mRNA expression in circulating tumor cells (CTCs) from metastatic castration resistance prostate cancer patients

Androgen receptor (AR) signaling drives prostate cancer (PC) progression and remains active upon transition to castration resistant prostate cancer (CRPC). Active AR signaling is achieved through the nuclear accumulation of AR following ligand binding and through expression of ligand-independent, constitutively active AR splice variants, such as AR-V7, which is the most commonly expressed variant in metastatic CRPC (mCRPC) patients. Most currently approved PC therapies aim to abrogate AR signaling and activity by inhibiting this ligand-mediated nuclear translocation. In a prospective multi-institutional clinical study, we recently showed that taxane based chemotherapy is also capable of impairing AR nuclear localization (ARNL) in circulating tumor cells (CTCs) from CRPC patients, whereas taxane induced decreases in ARNL were associated with response. Thus, quantitative assessment of ARNL in CTCs can be used to monitor therapeutic response in patients and help guide clinical decisions. Here, we describe the development and implementation of quantitative high throughput (QHT) image analysis algorithms to aid in CTC identification and quantitative assessment of percent ARNL (%ARNL). We applied this algorithm to fifteen CRPC patients at the start of taxane chemotherapy, quantified %ARNL in CTCs, and correlated with expression of AR-V7 mRNA (from CTCs enriched via negative, CD45⁺ depletion of peripheral blood) and with biochemical (prostate specific antigen; PSA) response to taxane chemotherapy. We found that CTCs from AR-V7 positive patients had higher baseline %ARNL compared to CTCs from AR-V7 negative patients, consistent with the constitutive nuclear localization of AR-V7. In addition, lower %ARNL in CTCs at baseline was associated with biochemical response to taxane chemotherapy. High inter- and intra-patient heterogeneity was also observed. As ARNL is required for active AR signaling, the QHT algorithms described herein can provide prognostic and/or predictive value in future clinical studies.

Randomized Phase II Trial of Abiraterone Alone or With Dasatinib in Men With Metastatic Castration-resistant Prostate Cancer (mCRPC)

BACKGROUND

Signaling via the Src pathway is thought to be a mediator of resistance to androgen targeted therapy in prostate cancer. We studied whether adding the Src inhibitor dasatinib to abiraterone would delay progression.

PATIENTS AND METHODS

Eligible patients had metastatic castration-resistant prostate cancer (mCRPC), without prior chemotherapy. Abiraterone was prescribed at 1000 mg daily with prednisone 5 mg twice daily in both arms, and dasatinib 100 mg daily was added for Arm B. The primary endpoint was progression-free survival (PFS). The interim analysis was planned after 48 subjects, but the study was terminated early. PFS was evaluated using a 1-sided log rank test. The Fisher exact test was used for other categorical data analyses. Circulating tumor cells (CTCs) were identified with the Epic platform.

RESULTS

With 26 men randomized and a median follow up of 41.8 months, the median PFS was 15.7 months (95% confidence interval, 8.2-49.0+ months) for Arm B and 9.0 months (95% confidence interval, 4.4-30.7 months) for Arm A (P = .15). Response Evaluation Criteria in Solid Tumors responses were seen in 5 (36%) of 14 patients, including 2 complete responses (CRs) on Arm B, and 2 (17%) of 12 responses without CR on Arm A (P = .39). Grade ≥ 3 toxicities more common in Arm B included hypertension, pleural effusion/dyspnea, and gastrointestinal effects. CTCs were detected at baseline in 10 of 19 evaluable patients (median, 2.7/mL blood [range 0.41-59.7]). At week 4, CTCs increased in 1 (10%) of 10 patients on Arm A and 4 (44%) of 9 patients on Arm B.

CONCLUSION

Dasatinib did not significantly prolong PFS in combination with abiraterone, although power was limited owing to the incomplete study cohort. Treatment with the combination was associated with robust objective responses, including Response Evaluation Criteria in Solid Tumors CRs.

Circulating Tumor Cells: Overview and Opportunities in Cytology

Circulating tumor cells (CTCs) have long been assumed to be the substrate of cancer metastasis. However, only in recent years have we begun to leverage the potential of CTCs found in minimally invasive peripheral blood specimens to improve care for cancer patients. Currently, CTC enumeration is an accepted prognostic indicator for breast, prostate, and colorectal cancer; however, CTC enumeration remains largely a research tool. More recently, the focus has shifted to CTC characterization and isolation which holds great promise for predictive testing. This review summarizes the relevant clinical, biological, and technical background necessary for pathologists and cytopathologists to appreciate the potential of CTC techniques. A summary of relevant systematic reviews of CTCs for specific cancers is then presented, as well as potential applications to precision medicine. Finally, we suggest future applications of CTC technologies that can be easily incorporated in the pathology laboratory, with the recommendation that pathologists and particularly cytopathologists apply these technologies to small specimens in the era of "doing more with less."

Opportunities and Challenges in Implementation of Multiparameter Single Cell Analysis Platforms for Clinical Translation

The high-content interrogation of single cells with platforms optimized for the multiparameter characterization of cells in liquid and solid biopsy samples can enable characterization of heterogeneous populations of cells ex vivo. Doing so will advance the diagnosis, prognosis, and treatment of cancer and other diseases. However, it is important to understand the unique issues in resolving heterogeneity and variability at the single cell level before navigating the validation and regulatory requirements in order for these technologies to impact patient care. Since 2013, leading experts representing industry, academia, and government have been brought together as part of the Foundation for the National Institutes of Health (FNIH) Biomarkers Consortium to foster the potential of high-content data integration for clinical translation.

Multiplex protein detection on circulating tumor cells from liquid biopsies using imaging mass cytometry

Molecular analysis of circulating and disseminated tumor cells (CTCs/DTCs) has great potential as a means for continuous evaluation of prognosis and treatment efficacy in near-real time through minimally invasive liquid biopsies. To realize this potential, however, methods for molecular analysis of these rare cells must be developed and validated. Here, we describe the integration of imaging mass cytometry (IMC) using metal-labeled antibodies as implemented on the Fluidigm Hyperion Imaging System into the workflow of the previously established High Definition Single Cell Analysis (HD-SCA) assay for liquid biopsies, along with methods for image analysis and signal normalization. Using liquid biopsies from a metastatic prostate cancer case, we demonstrate that IMC can extend the reach of CTC characterization to include dozens of protein biomarkers, with the potential to understand a range of biological properties that could affect therapeutic response, metastasis and immune surveillance when coupled with simultaneous phenotyping of thousands of leukocytes.

Clonal diversity revealed by morphoproteomic and copy number profiles of single prostate cancer cells at diagnosis

Tumor heterogeneity is prevalent in both treatment-naïve and end-stage metastatic castration-resistant prostate cancer (PCa), and may contribute to the broad range of clinical presentation, treatment response, and disease progression. To characterize molecular heterogeneity associated with de novo metastatic PCa, multiplatform single cell profiling was performed using high definition single cell analysis (HD-SCA). HD-SCA enabled morphoproteomic and morphogenomic profiling of single cells from touch preparations of tissue cores (prostate and bone marrow biopsies) as well as liquid samples (peripheral blood and bone marrow aspirate). Morphology, nuclear features, copy number alterations, and protein expression were analyzed. Tumor cells isolated from prostate tissue touch preparation (PTTP) and bone marrow touch preparation (BMTP) as well as metastatic tumor cells (MTCs) isolated from bone marrow aspirate were characterized by morphology and cytokeratin expression. Although peripheral blood was examined, circulating tumor cells were not definitively observed. Targeted proteomics of PTTP, BMTP, and MTCs revealed cell lineage and luminal prostate epithelial differentiation associated with PCa, including co-expression of EpCAM, PSA, and PSMA. Androgen receptor expression was highest in MTCs. Hallmark PCa copy number alterations, including PTEN and ETV6 deletions and NCOA2 amplification, were observed in cells within the primary tumor and bone marrow biopsy samples. Genomic landscape of MTCs revealed to be a mix of both primary and bone metastatic tissue. This multiplatform analysis of single cells reveals several clonal origins of metastatic PCa in a newly diagnosed, untreated patient with polymetastatic disease. This case demonstrates that real-time molecular profiling of cells collected through prostate and bone marrow biopsies is feasible and has the potential to elucidate the origin and evolution of metastatic tumor cells. Altogether, biological and genomic data obtained through longitudinal biopsies can be used to reveal the properties of PCa and can impact clinical management.

Classification of large circulating tumor cells isolated with ultra-high throughput microfluidic Vortex technology

Circulating tumor cells (CTCs) are emerging as rare but clinically significant non-invasive cellular biomarkers for cancer patient prognosis, treatment selection, and treatment monitoring. Current CTC isolation approaches, such as immunoaffinity, filtration, or size-based techniques, are often limited by throughput, purity, large output volumes, or inability to obtain viable cells for downstream analysis. For all technologies, traditional immunofluorescent staining alone has been employed to distinguish and confirm the presence of isolated CTCs among contaminating blood cells, although cells isolated by size may express vastly different phenotypes. Consequently, CTC definitions have been non-trivial, researcher-dependent, and evolving. Here we describe a complete set of objective criteria, leveraging well-established cytomorphological features of malignancy, by which we identify large CTCs. We apply the criteria to CTCs enriched from stage IV lung and breast cancer patient blood samples using the High Throughput Vortex Chip (Vortex HT), an improved microfluidic technology for the label-free, size-based enrichment and concentration of rare cells. We achieve improved capture efficiency (up to 83%), high speed of processing (8 mL/min of 10x diluted blood, or 800 μL/min of whole blood), and high purity (avg. background of 28.8±23.6 white blood cells per mL of whole blood). We show markedly improved performance of CTC capture (84% positive test rate) in comparison to previous Vortex designs and the current FDA-approved gold standard CellSearch assay. The results demonstrate the ability to quickly collect viable and pure populations of abnormal large circulating cells unbiased by molecular characteristics, which helps uncover further heterogeneity in these cells.

Effect of Blood Collection Tube Type and Time to Processing on the Enumeration and High-Content Characterization of Circulating Tumor Cells Using the High-Definition Single-Cell Assay

CONTEXT

- As circulating tumor cell (CTC) assays gain clinical relevance, it is essential to address preanalytic variability and to develop standard operating procedures for sample handling in order to successfully implement genomically informed, precision health care.

OBJECTIVE

- To evaluate the effects of blood collection tube (BCT) type and time-to-assay (TTA) on the enumeration and high-content characterization of CTCs by using the high-definition single-cell assay (HD-SCA).

DESIGN

- Blood samples of patients with early- and advanced-stage breast cancer were collected into cell-free DNA (CfDNA), EDTA, acid-citrate-dextrose solution, and heparin BCTs. Time-to-assay was evaluated at 24 and 72 hours, representing the fastest possible and more routine domestic shipping intervals, respectively.

RESULTS

- We detected the highest CTC levels and the lowest levels of negative events in CfDNA BCT at 24 hours. At 72 hours in this BCT, all CTC subpopulations were decreased with the larger effect observed in high-definition CTCs and cytokeratin-positive cells smaller than white blood cells. Overall cell retention was also optimal in CfDNA BCT at 24 hours. Whole-genome copy number variation profiles were generated from single cells isolated from all BCT types and TTAs. Cells from CfDNA BCT at 24-hour TTA exhibited the least noise.

CONCLUSIONS

- Circulating tumor cells can be identified and characterized under a variety of collection, handling, and processing conditions, but the highest quality can be achieved with optimized conditions. We quantified performance differences of the HD-SCA for specific preanalytic variables that may be used as a guide to develop best practices for implementation into patient care and/or research biorepository processes.

Extracellular vesicles for personalized therapy decision support in advanced metastatic cancers and its potential impact for prostate cancer

The use of circulating tumor cells (CTCs) and circulating extracellular vesicles (EVs), such as exosomes, as liquid biopsy-derived biomarkers for cancers have been investigated. CTC enumeration using the CellSearch based platform provides an accurate insight on overall survival where higher CTC counts indicate poor prognosis for patients with advanced metastatic cancer. EVs provide information based on their lipid, protein, and nucleic acid content and can be isolated from biofluids and analyzed from a relatively small volume, providing a routine and non-invasive modality to monitor disease progression. Our pilot experiment by assessing the level of two subpopulations of small EVs, the CD9 positive and CD63 positive EVs, showed that the CD9 positive EV level is higher in plasma from patients with advanced metastatic prostate cancer with detectable CTCs. These data show the potential utility of a particular EV subpopulation to serve as biomarkers for advanced metastatic prostate cancer. EVs can potentially be utilized as biomarkers to provide accurate genotypic and phenotypic information for advanced prostate cancer, where new strategies to design a more personalized therapy is currently the focus of considerable investigation.

Using circulating tumor cells to advance precision medicine in prostate cancer

The field of CTC enrichment has seen many emerging technologies in recent years, which have resulted in the identification and monitoring of clinically relevant, CTC-based biomarkers that can be analyzed routinely without invasive procedures. Several molecular platforms have been used to investigate the molecular profile of the disease, from high throughput gene expression analyses down to single cell biological dissection. The established presence of CTC heterogeneity nevertheless constitutes a challenge for cell isolation as the several subpopulations can potentially display different molecular characteristics; in this scenario, careful consideration must be given to the isolation approach, whereas methods that discriminate against certain subpopulations may result in the exclusion of CTCs that carry biological relevance. In the context of prostate cancer (PC), CTC molecular interrogation can enable longitudinal monitoring of key biological features during treatment with substantial clinical impact, as several biomarkers could predict tumor response to AR signaling inhibitors (abiraterone, enzalutamide) or standard chemotherapy (taxanes). Thus, CTCs represent a valuable opportunity to personalize medicine in current clinical practice.

Monolithic Chip for High-throughput Blood Cell Depletion to Sort Rare Circulating Tumor Cells

Circulating tumor cells (CTCs) are a treasure trove of information regarding the location, type and stage of cancer and are being pursued as both a diagnostic target and a means of guiding personalized treatment. Most isolation technologies utilize properties of the CTCs themselves such as surface antigens (e.g., epithelial cell adhesion molecule or EpCAM) or size to separate them from blood cell populations. We present an automated monolithic chip with 128 multiplexed deterministic lateral displacement devices containing ~1.5 million microfabricated features (12 µm–50 µm) used to first deplete red blood cells and platelets. The outputs from these devices are serially integrated with an inertial focusing system to line up all nucleated cells for multi-stage magnetophoresis to remove magnetically-labeled white blood cells. The monolithic CTC-iChip enables debulking of blood samples at 15–20 million cells per second while yielding an output of highly purified CTCs. We quantified the size and EpCAM expression of over 2,500 CTCs from 38 patient samples obtained from breast, prostate, lung cancers, and melanoma. The results show significant heterogeneity between and within single patients. Unbiased, rapid, and automated isolation of CTCs using monolithic CTC-iChip will enable the detailed measurement of their physicochemical and biological properties and their role in metastasis.

Circulating Tumor Cells: Moving Biological Insights into Detection

Circulating tumor cells (CTCs) have shown promising potential as liquid biopsies that facilitate early detection, prognosis, therapeutic target selection and monitoring treatment response. CTCs in most cancer patients are low in abundance and heterogeneous in morphological and phenotypic profiles, which complicate their enrichment and subsequent characterization. Several methodologies for CTC enrichment and characterization have been developed over the past few years. However, integrating recent advances in CTC biology into these methodologies and the selection of appropriate enrichment and characterization methods for specific applications are needed to improve the reliability of CTC biopsies. In this review, we summarize recent advances in the studies of CTC biology, including the mechanisms of their generation and their potential forms of existence in blood, as well as the current CTC enrichment technologies. We then critically examine the selection of methods for appropriately enriching CTCs for further investigation of their clinical applications.

Automated electrorotation shows electrokinetic separation of pancreatic cancer cells is robust to acquired chemotherapy resistance, serum starvation, and EMT

We used automated electrorotation to measure the cytoplasmic permittivity, cytoplasmic conductivity, and specific membrane capacitance of pancreatic cancer cells under environmental perturbation to evaluate the effects of serum starvation, epithelial-to-mesenchymal transition, and evolution of chemotherapy resistance which may be associated with the development and dissemination of cancer. First, we compared gemcitabine-resistant BxPC3 subclones with gemcitabine-naive parental cells. Second, we serum-starved BxPC3 and PANC-1 cells and compared them to untreated counterparts. Third, we induced the epithelial-to-mesenchymal transition in PANC-1 cells and compared them to untreated PANC-1 cells. We also measured the electrorotation spectra of white blood cells isolated from a healthy donor. The properties from fit electrorotation spectra were used to compute dielectrophoresis (DEP) spectra and crossover frequencies. For all three experiments, the median crossover frequency for both treated and untreated pancreatic cancer cells remained significantly lower than the median crossover frequency for white blood cells. The robustness of the crossover frequency to these treatments indicates that DEP is a promising technique for enhancing capture of circulating cancer cells.

Paired High-Content Analysis of Prostate Cancer Cells in Bone Marrow and Blood Characterizes Increased Androgen Receptor Expression in Tumor Cell Clusters

Purpose: Recent studies demonstrate that prostate cancer clones from different metastatic sites are dynamically represented in the blood of patients over time, suggesting that the paired evaluation of tumor cells in circulation and bone marrow, the primary target for prostate cancer metastasis, may provide complementary information.Experimental Design: We adapted our single-cell high-content liquid biopsy platform to bone marrow aspirates (BMA) to concurrently identify and characterize prostate cancer cells in patients' blood and bone and thus discern features associated to tumorigenicity and dynamics of metastatic progression.Results: The incidence of tumor cells in BMAs increased as the disease advanced: 0% in biochemically recurrent (n = 52), 26% in newly diagnosed metastatic hormone-naïve (n = 26), and 39% in metastatic castration-resistant prostate cancer (mCRPC; n = 63) patients, and their number was often higher than in paired blood. Tumor cell detection in metastatic patients' BMAs was concordant but 45% more sensitive than using traditional histopathologic interpretation of core bone marrow biopsies. Tumor cell clusters were more prevalent and bigger in BMAs than in blood, expressed higher levels of the androgen receptor protein per tumor cell, and were prognostic in mCRPC. Moreover, the patterns of genomic copy number variation in single tumor cells in paired blood and BMAs showed significant inter- and intrapatient heterogeneity.Conclusions: Paired analysis of single prostate cancer cells in blood and bone shows promise for clinical application and provides complementary information. The high prevalence and prognostic significance of tumor cell clusters, particularly in BMAs, suggest that these structures are key mediators of prostate cancer's metastatic progression. Clin Cancer Res; 23(7); 1722-32. ©2016 AACR.

Systems Pharmacology Modeling of Prostate-Specific Antigen in Patients With Prostate Cancer Treated With an Androgen Receptor Antagonist and Down-Regulator

First‐in‐human (FIH) studies with AZD3514, a selective androgen receptor (AR) down‐regulator, showed decreases of >30% in the prostate‐specific antigen (PSA) in some patients. A modeling approach was adopted to understand these observations and define the optimum clinical use hypothesis for AZD3514 for clinical testing. Initial empirical modeling showed that only baseline PSA correlated significantly with this biological response, whereas drug concentration did not. To identify the mechanistic cause of this observation, a mechanism‐based model was first developed, which described the effects of AZD3514 on AR protein and PSA mRNA levels in LNCaP cells with and without dihydrotestosterone (DHT). Second, the mechanism‐based model was linked to a population pharmacokinetic (PK) model; PSA effects of clinical doses were subsequently simulated under different clinical conditions. This model was used to adjust the design of the ongoing clinical FIH study and direct the backup program.

Continuous Flow Deformability-Based Separation of Circulating Tumor Cells Using Microfluidic Ratchets

Circulating tumor cells (CTCs) offer tremendous potential for the detection and characterization of cancer. A key challenge for their isolation and subsequent analysis is the extreme rarity of these cells in circulation. Here, a novel label-free method is described to enrich viable CTCs directly from whole blood based on their distinct deformability relative to hematological cells. This mechanism leverages the deformation of single cells through tapered micrometer scale constrictions using oscillatory flow in order to generate a ratcheting effect that produces distinct flow paths for CTCs, leukocytes, and erythrocytes. A label-free separation of circulating tumor cells from whole blood is demonstrated, where target cells can be separated from background cells based on deformability despite their nearly identical size. In doping experiments, this microfluidic device is able to capture >90% of cancer cells from unprocessed whole blood to achieve 10(4) -fold enrichment of target cells relative to leukocytes. In patients with metastatic castration-resistant prostate cancer, where CTCs are not significantly larger than leukocytes, CTCs can be captured based on deformability at 25× greater yield than with the conventional CellSearch system. Finally, the CTCs separated using this approach are collected in suspension and are available for downstream molecular characterization.

Circulating tumor cell technologies†

Circulating tumor cells, a component of the “liquid biopsy”, hold great potential to transform the current landscape of cancer therapy. A key challenge to unlocking the clinical utility of CTCs lies in the ability to detect and isolate these rare cells using methods amenable to downstream characterization and other applications. In this review, we will provide an overview of current technologies used to detect and capture CTCs with brief insights into the workings of individual technologies. We focus on the strategies employed by different platforms and discuss the advantages of each. As our understanding of CTC biology matures, CTC technologies will need to evolve, and we discuss some of the present challenges facing the field in light of recent data encompassing epithelial‐to‐mesenchymal transition, tumor‐initiating cells, and CTC clusters.

We present a comprehensive overview of CTC detection and capture technologies.

We provide a conceptual description of strategies used in different technologies.

We highlight the key features of individual technologies.

We discuss CTC technology performance in the context of clinical studies.

Circulating Tumor Cells: When a Solid Tumor Meets a Fluid Microenvironment

Solid tumor dissemination from the primary site to the sites of metastasis involves tumor cell transport through the blood or lymph circulation systems. Once the tumor cells enter the bloodstream, they encounter a new hostile microenvironment. The cells must withstand hemodynamic forces and overcome the effects of fluid shear. The cells are exposed to immunological signaling insults from leukocytes, to collisions with erythrocytes, and to interactions with platelets or macrophages. Finally, the cells need to attach to the blood vessel walls and extravasate to the surrounding stroma to form tumor metastases. Although only a small fraction of invasive cells is able to complete the metastatic process, most cancer-related deaths are the result of tumor metastasis. Thus, investigating the intracellular properties of circulating tumor cells and the extracellular conditions that allow the tumor cells to survive and thrive in this microenvironment is of vital interest. In this chapter, we discuss the intravascular microenvironment that the circulating tumor cells must endure. We summarize the current experimental and computational literature on tumor cells in the circulation system. We also illustrate various aspects of the intravascular transport of circulating tumor cells using a mathematical model based on immersed boundary principles.

Using circulating tumor cells to inform on prostate cancer biology and clinical utility

Substantial advances in the molecular biology of prostate cancer have led to the approval of multiple new systemic agents to treat men with metastatic castration-resistant prostate cancer (mCRPC). These treatments encompass androgen receptor directed therapies, immunotherapies, bone targeting radiopharmaceuticals and cytotoxic chemotherapies. There is, however, great heterogeneity in the degree of patient benefit with these agents, thus fueling the need to develop predictive biomarkers that are able to rationally guide therapy. Circulating tumor cells (CTCs) have the potential to provide an assessment of tumor-specific biomarkers through a non-invasive, repeatable "liquid biopsy" of a patient's cancer at a given point in time. CTCs have been extensively studied in men with mCRPC, where CTC enumeration using the Cellsearch® method has been validated and FDA approved to be used in conjunction with other clinical parameters as a prognostic biomarker in metastatic prostate cancer. In addition to enumeration, more sophisticated molecular profiling of CTCs is now feasible and may provide more clinical utility as it may reflect tumor evolution within an individual particularly under the pressure of systemic therapies. Here, we review technologies used to detect and characterize CTCs, and the potential biological and clinical utility of CTC molecular profiling in men with metastatic prostate cancer.

Circulating tumor microemboli diagnostics for patients with non-small-cell lung cancer

INTRODUCTION

Circulating tumor microemboli (CTM) are potentially important cancer biomarkers, but using them for cancer detection in early-stage disease has been assay limited. We examined CTM test performance using a sensitive detection platform to identify stage I non-small-cell lung cancer (NSCLC) patients undergoing imaging evaluation.

METHODS

First, we prospectively enrolled patients during 18F-FDG PET-CT imaging evaluation for lung cancer that underwent routine phlebotomy where CTM and circulating tumor cells (CTCs) were identified in blood using nuclear (DAPI), cytokeratin (CK), and CD45 immune-fluorescent antibodies followed by morphologic identification. Second, CTM and CTC data were integrated with patient (age, gender, smoking, and cancer history) and imaging (tumor diameter, location in lung, and maximum standard uptake value [SUVmax]) data to develop and test multiple logistic regression models using a case-control design in a training and test cohort followed by cross-validation in the entire group.

RESULTS

We examined 104 patients with NSCLC, and the subgroup of 80 with stage I disease, and compared them to 25 patients with benign disease. Clinical and imaging data alone were moderately discriminating for all comers (Area under the Curve [AUC] = 0.77) and by stage I disease only (AUC = 0.77). However, the presence of CTM combined with clinical and imaging data was significantly discriminating for diagnostic accuracy in all NSCLC patients (AUC = 0.88, p value = 0.001) and for stage I patients alone (AUC = 0.87, p value = 0.002).

CONCLUSION

CTM may add utility for lung cancer diagnosis during imaging evaluation using a sensitive detection platform.

Advancing cancer patient care by integrating circulating tumor cell technology to understand the spatial and temporal dynamics of cancer

Spatial and temporal dynamics of cancer, studied with physical science approaches at critical transition points of the disease can provide insight into the biology of cancer and the evolutionary changes that occur both naturally and in response to therapy. A very promising development in translational cancer medicine has been the emergence of circulating tumor cells (CTC) as minimally invasive "liquid biopsies." We envision that the future utility of CTC will not simply be confined to enumeration, but also include their routine characterization using a high-content approach that investigates morphometrics, protein expression and genomic profiling. This novel approach guided by mathematical models to predict the spread of disease from the primary site to secondary site can bring the bench to the bedside for cancer patients. It is agnostic with reference to drug choice and treatment regimen, which also means that each patient is unique. The approach is Bayesian from a data collection perspective and is patient-centric rather than drug or new chemical entity-centric. The analysis of data comes from an understanding of commonalities and differences that are detected among patients with a given cancer type. Thus, patients are treated over the course of their disease with various drug regimens that reflects our real-time understanding of their evolving tumor genomics and response to treatment. This likely means that smaller cohorts of patients receive any given regimen but we hypothesize that it would lead to better patient outcomes than with the current classic approach to drug testing and development.

Combined genome and transcriptome analysis of single disseminated cancer cells from bone marrow of prostate cancer patients reveals unexpected transcriptomes

Bone is the most frequent site of metastasis in prostate cancer and patients with bone metastases are deemed incurable. Targeting prostate cancer cells that disseminated to the bone marrow before surgery and before metastatic outgrowth may therefore prevent lethal metastasis. This prompted us to directly analyze the transcriptome of disseminated cancer cells (DCC) isolated from patients with nonmetastatic (UICC stage M0) prostate cancer. We screened 105 bone marrow samples of patients with M0-stage prostate cancer and 18 bone marrow samples of patients without malignancy for the presence of EpCAM(+) single cells. In total, we isolated 270 cells from both groups by micromanipulation and globally amplified their mRNA. We used targeted transcriptional profiling to unambiguously identify DCCs for subsequent in-depth analysis. Transcriptomes of all cells were examined for the expression of EPCAM, KRT8, KRT18, KRT19, KRT14, KRT6a, KRT5, KLK3 (PSA), MAGEA2, MAGEA4, PTPRC (CD45), CD33, CD34, CD19, GYPC, SCL4A1 (band 3), and HBA2. Using these transcripts, we found it impossible to reliably identify true DCCs. We then applied combined genome and transcriptome analysis of single cells and found that EpCAM(+) cells from controls expressed transcripts thought to be epithelial-specific, whereas true DCCs may express hematopoietic transcripts. These results point to an unexpected transcriptome plasticity of epithelial cancer cells in bone marrow and question common transcriptional criteria to identify DCCs.

Rapid phenotypic and genomic change in response to therapeutic pressure in prostate cancer inferred by high content analysis of single circulating tumor cells

Timely characterization of a cancer's evolution is required to predict treatment efficacy and to detect resistance early. High content analysis of single Circulating Tumor Cells (CTCs) enables sequential characterization of genotypic, morphometric and protein expression alterations in real time over the course of cancer treatment. This concept was investigated in a patient with castrate-resistant prostate cancer progressing through both chemotherapy and targeted therapy. In this case study, we integrate across four timepoints 41 genome-wide copy number variation (CNV) profiles plus morphometric parameters and androgen receptor (AR) protein levels. Remarkably, little change was observed in response to standard chemotherapy, evidenced by the fact that a unique clone (A), exhibiting highly rearranged CNV profiles and AR+ phenotype was found circulating before and after treatment. However, clinical response and subsequent progression after targeted therapy was associated with the drastic depletion of clone A, followed by the sequential emergence of two distinct CTC sub-populations that differed in both AR genotype and expression phenotype. While AR- cells with flat or pseudo-diploid CNV profiles (clone B) were identified at the time of response, a new tumor lineage of AR+ cells (clone C) with CNV altered profiles was detected during relapse. We showed that clone C, despite phylogenetically related to clone A, possessed a unique set of somatic CNV alterations, including MYC amplification, an event linked to hormone escape. Interesting, we showed that both clones acquired AR gene amplification by deploying different evolutionary paths. Overall, these data demonstrate the timeframe of tumor evolution in response to therapy and provide a framework for the multi-scale analysis of fluid biopsies to quantify and monitor disease evolution in individual patients.

Circulating tumor cells in prostate cancer diagnosis and monitoring: an appraisal of clinical potential

Circulating tumor cells (CTCs) have emerged as a viable solution to the lack of tumor tissue availability for patients with a variety of solid tumors, including prostate cancer. Different approaches have been used to capture this tumor cell population and several of these techniques have been used to assess the potential role of CTCs as a biological marker to predict treatment efficacy and clinical outcome. CTCs are now considered a strong tool to understand the molecular characteristics of prostate cancer, and to be used and analyzed as a 'liquid biopsy' in the attempt to grasp the biological portrait of the disease in the individual patient.

Circulating tumour cells-monitoring treatment response in prostate cancer

The availability of new therapeutic options for the treatment of metastatic castration-resistant prostate cancer (mCRPC) has heightened the importance of monitoring and assessing treatment response. Accordingly, there is an unmet clinical need for reliable biomarkers that can be used to guide therapy. Circulating tumour cells (CTCs) are rare cells that are shed from primary and metastatic tumour deposits into the peripheral circulation, and represent a means of performing noninvasive tumour sampling. Indeed, enumeration of CTCs before and after therapy has shown that CTC burden correlates with prognosis in patients with mCRPC. Moreover, studies have demonstrated the potential of molecular analysis of CTCs in monitoring and predicting response to therapy in patients. This Review describes the challenges associated with monitoring treatment response in mCRPC, and the advancements in CTC-analysis technologies applied to such assessments and, ultimately, guiding prostate cancer treatment.

Blood-based analyses of cancer: circulating tumor cells and circulating tumor DNA

The ability to study nonhematologic cancers through noninvasive sampling of blood is one of the most exciting and rapidly advancing fields in cancer diagnostics. This has been driven both by major technologic advances, including the isolation of intact cancer cells and the analysis of cancer cell-derived DNA from blood samples, and by the increasing application of molecularly driven therapeutics, which rely on such accurate and timely measurements of critical biomarkers. Moreover, the dramatic efficacy of these potent cancer therapies drives the selection for additional genetic changes as tumors acquire drug resistance, necessitating repeated sampling of cancer cells to adjust therapy in response to tumor evolution. Together, these advanced noninvasive diagnostic capabilities and their applications in guiding precision cancer therapies are poised to change the ways in which we select and monitor cancer treatments.

SIGNIFICANCE

Recent advances in technologies to analyze circulating tumor cells and circulating tumor DNA are setting the stage for real-time, noninvasive monitoring of cancer and providing novel insights into cancer evolution, invasion, and metastasis.

Recent advances in the molecular characterization of circulating tumor cells

Although circulating tumor cells (CTCs) were first observed over a century ago, lack of sensitive methodology precluded detailed study of these cells until recently. However, technological advances have now facilitated the identification, enumeration, and characterization of CTCs using a variety of methods. The majority of evidence supporting the use of CTCs in clinical decision-making has been related to enumeration using the CellSearch® system and correlation with prognosis. Growing evidence also suggests that CTC monitoring can provide an early indication of patient treatment response based on comparison of CTC levels before and after therapy. However, perhaps the greatest potential that CTCs hold for oncology lies at the level of molecular characterization. Clinical treatment decisions may be more effective if they are based on molecular characteristics of metastatic cells rather than on those of the primary tumor alone. Molecular characterization of CTCs (which can be repeatedly isolated in a minimally invasive fashion) provides the opportunity for a "real-time liquid biopsy" that allows assessment of genetic drift, investigation of molecular disease evolution, and identification of actionable genomic characteristics. This review focuses on recent advances in this area, including approaches involving immunophenotyping, fluorescence in situ hybridization (FISH), multiplex RT-PCR, microarray, and genomic sequencing.

Morphological differences between circulating tumor cells from prostate cancer patients and cultured prostate cancer cells

Circulating tumor cell (CTC) enumeration promises to be an important predictor of clinical outcome for a range of cancers. Established CTC enumeration methods primarily rely on affinity capture of cell surface antigens, and have been criticized for underestimation of CTC numbers due to antigenic bias. Emerging CTC capture strategies typically distinguish these cells based on their assumed biomechanical characteristics, which are often validated using cultured cancer cells. In this study, we developed a software tool to investigate the morphological properties of CTCs from patients with castrate resistant prostate cancer and cultured prostate cancer cells in order to establish whether the latter is an appropriate model for the former. We isolated both CTCs and cultured cancer cells from whole blood using the CellSearch® system and examined various cytomorphological characteristics. In contrast with cultured cancer cells, CTCs enriched by CellSearch® system were found to have significantly smaller size, larger nuclear-cytoplasmic ratio, and more elongated shape. These CTCs were also found to exhibit significantly more variability than cultured cancer cells in nuclear-cytoplasmic ratio and shape profile.

Size-selective collection of circulating tumor cells using Vortex technology

A blood-based, low cost alternative to radiation intensive CT and PET imaging is critically needed for cancer prognosis and management of its treatment. "Liquid biopsies" of circulating tumor cells (CTCs) from a relatively non-invasive blood draw are particularly ideal, as they can be repeated regularly to provide up to date molecular information about the cancer, which would also open up key opportunities for personalized therapies. Beyond solely diagnostic applications, CTCs are also a subject of interest for drug development and cancer research. In this paper, we adapt a technology previously introduced, combining the use of micro-scale vortices and inertial focusing, specifically for the high-purity extraction of CTCs from blood samples. First, we systematically varied parameters including channel dimensions and flow rates to arrive at an optimal device for maximum trapping efficiency and purity. Second, we validated the final device for capture of cancer cell lines in blood, considering several factors, including the effect of blood dilution, red blood cell lysis and cell deformability, while demonstrating cell viability and independence on EpCAM expression. Finally, as a proof-of-concept, CTCs were successfully extracted and enumerated from the blood of patients with breast (N = 4, 25-51 CTCs per 7.5 mL) and lung cancer (N = 8, 23-317 CTCs per 7.5 mL). Importantly, samples were highly pure with limited leukocyte contamination (purity 57-94%). This Vortex approach offers significant advantages over existing technologies, especially in terms of processing time (20 min for 7.5 mL of whole blood), sample concentration (collecting cells in a small volume down to 300 μL), applicability to various cancer types, cell integrity and purity. We anticipate that its simplicity will aid widespread adoption by clinicians and biologists who desire to not only enumerate CTCs, but also uncover new CTC biology, such as unique gene mutations, vesicle secretion and roles in metastatic processes.

Physical biology in cancer. 2. The physical biology of circulating tumor cells

The identification, isolation, and characterization of circulating tumor cells (CTCs) promises to enhance our understanding of the evolution of cancer in humans. CTCs provide a window into the hematogenous, or "fluid phase," of cancer, underlying the metastatic transition in which a locally contained tumor spreads to other locations in the body through the bloodstream. With the development of sensitive and specific CTC identification and isolation methodologies, the role of CTCs in clinical diagnostics, disease surveillance, and the physical basis of metastasis continues to be established. This review focuses on the quantification of the basic biophysical properties of CTCs and the use of these metrics to understand the hematogenous dissemination of these enigmatic cells.

Circulating tumor cells: advances in isolation and analysis, and challenges for clinical applications

Circulating tumor cells (CTCs) are rare cancer cells released from tumors into the bloodstream that are thought to have a key role in cancer metastasis. The presence of CTCs has been associated with worse prognosis in several major cancer types, including breast, prostate and colorectal cancer. There is considerable interest in CTC research and technologies for their potential use as cancer biomarkers that may enhance cancer diagnosis and prognosis, facilitate drug development, and improve the treatment of cancer patients. This review provides an update on recent progress in CTC isolation and molecular characterization technologies. Furthermore, the review covers significant advances and limitations in the clinical applications of CTC-based assays for cancer prognosis, response to anti-cancer therapies, and exploratory studies in biomarkers predictive of sensitivity and resistance to cancer therapies.

Mutational Analysis of Circulating Tumor Cells Using a Novel Microfluidic Collection Device and qPCR Assay

Circulating tumor cells (CTCs) provide a readily accessible source of tumor material from patients with cancer. Molecular profiling of these rare cells can lead to insight on disease progression and therapeutic strategies. A critical need exists to isolate CTCs with sufficient quantity and sample integrity to adapt to conventional analytical techniques. We present a microfluidic platform (IsoFlux) that uses flow control and immunomagnetic capture to enhance CTC isolation. A novel cell retrieval mechanism ensures complete transfer of CTCs into the molecular assay. Improved sensitivity to the capture antigen was demonstrated by spike-in experiments for three cell lines of varying levels of antigen expression. We obtained spike-in recovery rates of 74%, 75%, and 85% for MDA-MB-231 (low), PC3 (middle), and SKBR3 (high) cell lines. Recovery using matched enumeration protocols and matched samples (PC3) yielded 90% and 40% recovery for the IsoFlux and CellSearch systems, respectively. In matched prostate cancer samples (N = 22), patients presenting more than four CTCs per blood draw were 95% and 36% using IsoFlux and CellSearch, respectively. An assay for detecting KRAS mutations was described along with data from patients with colorectal cancer, of which 87% presented CTCs above the assay's limit of detection (four CTCs). The CTC KRAS mutant rate was 50%, with 46% of patients displaying a CTC KRAS mutational status that differed from the previously acquired tissue biopsy data. The microfluidic system and mutation assay presented here provide a complete workflow to track oncogene mutational changes longitudinally with high success rates.

Immunomagnetic nanoscreening of circulating tumor cells with a motion controlled microfluidic system

Combining the power of immunomagnetic assay and microfluidic microchip operations, we successfully detected rare CTCs from clinical blood samples. The microfluidic system is operated in a flip-flop mode, where a computer-controlled rotational holder with an array of microfluidic chips inverts the microchannels. We have demonstrated both theoretically and experimentally that the direction of red blood cell (RBC) sedimentation with regards to the magnetic force required for cell separation is important for capture efficiency, throughput, and purity. The flip-flop operation reduces the stagnation of RBCs and non-specific binding on the capture surface by alternating the direction of the magnetic field with respect to gravity. The developed immunomagnetic microchip-based screening system exhibits high capture rates (more than 90%) for SkBr3, PC3, and Colo205 cell lines in spiked screening experiments and successfully isolates CTCs from patient blood samples. The proposed motion controlled microchip-based immunomagnetic system shows great promise as a clinical tool for cancer diagnosis and prognosis.

Fluid biopsy for solid tumors: a patient's companion for lifelong characterization of their disease

Cancer is currently diagnosed and treated based on the results of a tissue biopsy of the primary tumor or a metastasis using invasive techniques such as surgical resection or needle biopsy. New technology for retrieving cancer cells from the circulation, developed in the last 5 years, has made it possible to obtain a 'fluid biopsy' from the bloodstream without the need for an invasive procedure. This technological development makes it possible to diagnose and manage cancer from a blood test rather than from a traditional biopsy. It also allows the repeated sampling of cancer cells from a patient, making it possible, in a practical manner, to interrogate the disease repeatedly in order to understand the mechanisms by which cancer cells evolve within a given individual. The ability to obtain cancer cells repeatedly also has the potential to substantially advance drug development by enabling early ex vivo validation of both targets and early-stage compounds, as well as creating new efficiencies in the drug development process during clinical trials.