Circulating tumor cells (CTC) detection: clinical impact and future directions

Aptamer based strategy for cytosensing and evaluation of HER-3 on the surface of MCF-7 cells by using the signal amplification of nucleic acid-functionalized nanocrystals

The electrochemical detection of cell lines of MCF-7 (human breast cancer) has been reported, using magnetic beads for the separation tool and high-affinity DNA aptamers for signal recognition. The high specificity was obtained by using the magnetic beads and aptamers, and the good sensitivity was realized with the signal amplification of DNA capped CdS or PbS nanocrystals. The ASV (anodic stripping voltammetry) technology was employed for the detection of cadmic cation and lead ions, for electrochemical assay of the amount of the target cells and biomarkers on the membrane of target cells, respectively. This electrochemical method could respond to as low as 100 cells mL(-1) of cancer cells with a linear calibration range from 1.0×10(2) to 1.0×10(6) cells mL(-1), showing very high sensitivity. Moreover, the amounts of HER-3 which were overexpressed on MCF-7 cells were calculated correspond to be 3.56×10(4) anti-HER-3 antibody molecules. In addition, the assay was able to differentiate between different types of target and control cells based on the aptamers and magnetic beads used in the assay, indicating the wide applicability of the assay for early and accurate diagnose of cancers.

An automated high-throughput counting method for screening circulating tumor cells in peripheral blood

Enumeration of circulating tumor cells (CTCs) has proved valuable for early detection and prognosis in cancer treatment. This paper describes an automated high-throughput counting method for CTCs based on microfluidics and line-confocal microscopy. Peripheral blood was directly labeled with multiple antibodies, each conjugated with a different fluorophore, pneumatically pumped through a microfluidic channel, and interrogated by a line-confocal microscope. On the basis of the fluorescence signals and labeling schemes, the count of CTCs was automatically reported. Due to the high flow rate, 1 mL of whole blood can be analyzed in less than 30 min. We applied this method in analyzing CTCs from 90 stage IV breast cancer patient samples and performed a side-by-side comparison with the results of the CellSearch assay, which is the only method approved by the U.S. Food and Drug Administration at present for enumeration of CTCs. This method has a recovery rate for cultured breast cancer cells of 94% (n = 9), with an average of 1.2 counts/mL of background level of detected CTCs from healthy donors. It detected CTCs from breast cancer patients ranging from 15 to 3375 counts/7.5 mL. Using this method, we also demonstrate the ability to enumerate CTCs from breast cancer patients that were positive for Her2 or CD44(+)/CD24(-), which is a putative cancer stem cell marker. This automated method can enumerate CTCs from peripheral blood with high throughput and sensitivity. It could potentially benefit the clinical diagnosis and prognosis of cancer.

Electrochemiluminescence biosensor based on conducting poly(5-formylindole) for sensitive detection of Ramos cells

A signal-on electrochemiluminescence (ECL) biosensor devoted to the detection of Ramos cells was fabricated based on a novel conducting polymer, poly(5-formylindole) (P5FIn), which was synthesized electrochemically by direct anodic oxidation of 5-formylindole (5FIn). This ECL platform was presented by covalently coupling the 18-mer amino-substituted oligonucleotide (ODN) probes with aldehyde groups that are strongly reactive toward a variety of nucleophiles on the surface of solid substrates. The specific identification and high-affinity between aptamers and target cells, gold nanoparticles (AuNPs) enhanced ECL nanoprobes, along with P5FIn induced ECL quenching contributed greatly to the sensitivity and selectivity. The ECL signals were logarithmically linear with the concentration of Ramos cells in a wide determination range from 500 to 1.0 × 10(5) cells mL(-1), and the corresponding detection limit was 300 cells mL(-1).

Lung cancer circulating tumor cells isolated by the EpCAM-independent enrichment strategy correlate with Cytokeratin 19-derived CYFRA21-1 and pathological staging

BACKGROUND

Cytokeratin 19-derived CYFRA21-1 is an acceptable lung cancer biomarker. However, whether CYFRA21-1 correlates with lung cancer circulating tumor cells (CTCs) remains unclear.

METHODS

CTCs in 42 lung cancer patients and 10 nonmalignant pulmonary disease patients were isolated by means of an EpCAM-independent enrichment strategy. Correlation of lung cancer CTCs with serum concentration of CYFRA21-1 and pathological staging was investigated.

RESULTS

Among lung cancer patients in this study, 39% (7/18) of those with normal CYFRA21-1 (≤3.3 ng/ml) and 62% (13/21) of high CYFRA21-1 (>3.3 ng/ml) patients were found to have ≥3 CTCs/7.5 ml blood. The CTCs-positive rate of stage I to IV lung cancer patients was 20% (2/10), 45% (5/11), 54% (6/11) and 70% (7/10), respectively. Comparing M0 vs M1 patients, the CTCs-positive rate was 43% (13/30) and 70% (7/10), respectively. All M1 patients (10/10) had one or more CTCs detected, whereas none of the nonmalignant pulmonary disease patients had detectable CTCs.

CONCLUSION

Lung cancer CTCs isolated by the EpCAM-independent enrichment approach correlate with CYFRA21-1 and TNM staging. Correlation of CTCs and CYFRA21-1 in lung cancer patients is of potential clinical utility in terms of early diagnosis and predicting prognosis.

Phenotypic switch in blood: effects of pro-inflammatory cytokines on breast cancer cell aggregation and adhesion

Hematogeneous metastasis can occur via a cascade of circulating tumor cell adhesion events to the endothelial lining of the vasculature, i.e. the metastatic cascade. Interestingly, the pro-inflammatory cytokines IL-6 and TNF-α, which play an important role in potentiating the inflammatory cascade, are significantly elevated in metastatic breast cancer (BCa) patients. Despite their high metastatic potential, human breast carcinoma cells MDA-MB-231 lack interactions with E-selectin functionalized surfaces under physiological shear stresses. We hypothesized that human plasma, 3-D tumor spheroid culture, and cytokine-supplemented culture media could induce a phenotypic switch that allows BCa cells to interact with E-selectin coated surfaces under physiological flow. Flow cytometry, immunofluorescence imaging, and flow-based cell adhesion assay were utilized to investigate the phenotypic changes of MDA-MB-231 cells with various treatments. Our results indicate that plasma, IL-6, and TNF-α promote breast cancer cell growth as aggregates and induce adhesive recruitment of BCa cells on E-selectin coated surfaces under flow. 3-D tumor spheroid culture exhibits the most significant increases in the interactions between BCa and E-selectin coated surfaces by upregulating CD44V4 and sLe(x) expression. Furthermore, we show that IL-6 and TNF-α concentrations in blood may regulate the recruitment of BCa cells to the inflamed endothelium. Finally, we propose a mechanism that could explain the invasiveness of 'triple-negative' breast cancer cell line MDA-MB-231 via a positive feedback loop of IL-6 secretion and maintenance. Taken together, our results suggest that therapeutic approaches targeting cytokine receptors and adhesion molecules on cancer cells may potentially reduce metastatic load and improve current cancer treatments.

Key molecular mechanisms in lung cancer invasion and metastasis: a comprehensive review

Lung cancer remains one of the most common and malignant cancers worldwide. It is most often diagnosed at late stages, when it has already presented local invasion and distal metastases. The basic stages of invasion and metastasis involve the detachment of tumor cells from the extracellular matrix, invasion of surrounding tissues and basal lamina, intravasation into the blood stream, survival and transport through the blood stream, migration, arrest and extravasation at a distal site and formation of a metastatic lesion. These steps require fundamental mechanisms such as angiogenesis, degradation of matrix barriers, disruption of cell-cell and cell-matrix adhesion and inducement of cellular motility. Genes that regulate functions like unlimited growth potential, survival, genomic instability, angiogenesis, epithelial to mesenchymal transition and apoptosis evasion, are involved in giving lung cancer tumors invasive and metastatic competence. Improving of understanding of the underlying molecular and cellular mechanisms remains an urgent and essential issue, in order to develop new more effective strategies in preventing and treating lung cancer.

Dielectrophoresis has broad applicability to marker-free isolation of tumor cells from blood by microfluidic systems

The number of circulating tumor cells (CTCs) found in blood is known to be a prognostic marker for recurrence of primary tumors, however, most current methods for isolating CTCs rely on cell surface markers that are not universally expressed by CTCs. Dielectrophoresis (DEP) can discriminate and manipulate cancer cells in microfluidic systems and has been proposed as a molecular marker-independent approach for isolating CTCs from blood. To investigate the potential applicability of DEP to different cancer types, the dielectric and density properties of the NCI-60 panel of tumor cell types have been measured by dielectrophoretic field-flow fractionation (DEP-FFF) and compared with like properties of the subpopulations of normal peripheral blood cells. We show that all of the NCI-60 cell types, regardless of tissue of origin, exhibit dielectric properties that facilitate their isolation from blood by DEP. Cell types derived from solid tumors that grew in adherent cultures exhibited dielectric properties that were strikingly different from those of peripheral blood cell subpopulations while leukemia-derived lines that grew in non-adherent cultures exhibited dielectric properties that were closer to those of peripheral blood cell types. Our results suggest that DEP methods have wide applicability for the surface-marker independent isolation of viable CTCs from blood as well as for the concentration of leukemia cells from blood.

Markers of circulating breast cancer cells

The detection of circulating tumor cells (CTC) aids in diagnosis of disease, prognosis, disease recurrence, and therapeutic response. The molecular aspects of metastasis are reviewed including its relevance in the identification and characterization of putative markers that may be useful in the detection thereof. Also discussed are methods for CTC enrichment using molecular strategies. The clinical application of CTC in the metastatic disease process is also summarized.

Circulating tumor cells: personalized medicine in interventional oncology?

Innovative technologic advancements have expanded the ability of interventional radiologists to capture and visualize directly tumor cells that have intravasated into the circulation. The detection of these circulating tumor cells (CTCs) is revolutionizing the understanding of the pathogenesis of metastasis and is paving the way for exquisitely sensitive techniques to detect malignancy, monitor recurrence, and prognosticate outcomes. In this review, the prevailing theories on the pathobiology of metastasis and the tools that have been developed to investigate CTCs are summarized. The tremendous impact CTCs are likely to have in oncology is discussed, with particular emphasis on their relevance to interventional oncology.

Epithelial mesenchymal transition is required for acquisition of anoikis resistance and metastatic potential in adenoid cystic carcinoma

Human adenoid cystic carcinoma (ACC) is characterized by diffused invasion of the tumor into adjacent organs and early distant metastasis. Anoikis resistance and epithelial mesenchymal transition (EMT) are considered prerequisites for cancer cells to metastasize. Exploring the relationship between these processes and their underlying mechanism of action is a promising way to better understand ACC tumors. We initially established anoikis-resistant sublines of ACC cells; the variant cells revealed a mesenchymal phenotype through Slug-mediated EMT-like transformation and displayed enhanced metastatic potential both in vitro and in vivo. Suppression of EMT by knockdown of Slug significantly impaired anoikis resistance, migration, and invasion of the variant cells. With overexpression of Slug and Twist, we determined that induction of EMT in normal ACC cells could prevent anoikis, albeit partially. These findings strongly suggest that EMT is indispensable in anoikis resistance, at least in ACC cells. Furthermore, we found that the EGFR/PI3K/Akt pathway acts as the common regulator for EMT-like transformation and anoikis resistance, as confirmed by their specific inhibitors. Gefitinib and LY294003 restored the sensibilities of anoikis-resistant cells to anoikis and simultaneously impaired their metastatic potential. In addition, the results from our in vivo model of metastasis suggest that pretreatment with gefitinib promotes mouse survival by alleviating pulmonary metastasis. Most importantly, immunohistochemistry of human ACC specimens showed a correlation between the overexpression of Slug and EGFR staining. This study has demonstrated that Slug-mediated EMT-like transformation is required by human ACC cells to achieve anoikis resistance and their metastatic potential. Targeting the EGFR/PI3K/Akt pathway holds potential as a preventive strategy against distant metastasis of ACC.

Methylated APC and GSTP1 genes in serum DNA correlate with the presence of circulating blood tumor cells and are associated with a more aggressive and advanced breast cancer disease

Background

Tumor-related methylated DNA and circulating tumor cells (CTC) in the peripheral blood might be of prognostic importance in breast cancer. Thus, the aim of our study was to examine free methylated DNA and CTC in the blood from breast cancer patients and to correlate it with clinicopathological features known to influence prognosis.

Materials and methods

We prospectively obtained serum samples from 85 patients with breast cancer and 22 healthy volunteers. Sera were analysed by methylation specific PCR (MethyLight PCR) for five genes: adenomatous polyposis coli (APC), ras association domain family protein 1A (RASSF1A), estrogen receptor 1 (ESR1), CDKN2A (p16) and glutathione s-transferase pi 1 (GSTP1). Beta actin (ACTB) served as control. In parallel matched peripheral blood of 63 patients was used to assay for circulating tumor cells in the peripheral blood by a modified immunomagnetic AdnaTest BreastCancerSelect with PCR detection for EPCAM, MUC1, MGB1 and SPDEF.

Results

We found a hypermethylation in the APC gene in 29% (25/85), in RASSF1A in 26% (22/85), in GSTP1 in 18% (14/76) and in ESR1 in 38% (32/85) of all breast cancer patients. No hypermethylation of CDKN2A was found (0/25). Blood samples of patients were defined CTC positive by detecting the EPCAM 13% (8/63), MUC1 16% (10/63), MGB 9% (5/55), SPDEF 12% (7/58) and in 27% detecting one or more genes (15/55). A significant difference was seen in methylated APC DNA between cancer patients and healthy volunteers. Moreover, methylated APC, RASSF1 and CTC were significantly different in metastatic versus non-metastatic disease. In addition, the presence of methylated APC, RASSF1A and CTC correlated significantly with AJCC-staging (p = 0.001, p = 0.031 and 0.002, respectively). High incidences of methylations were found for the genes RASSF1 and ESR1 in healthy individuals (both 23% 5/22). Methylated GSTP1 was predominantly found in the serum of patients with large primaries (p = 0.023) and was highly significantly correlated with positive Her2/neu status (p = 0.003). Elevated serum CA15.3 was strongly correlated with methylated APC and CTC detection (both p = 0.000). Methylated ESR1 failed to exhibit significant correlations with any of the above mentioned parameters. The presence of CTC in peripheral blood was significantly associated with methylated APC (p = 0.012) and methylated GSTP1 (p = 0.001).

Conclusion

The detection of methylated APC and GSTP1 DNA in serum correlated with the presence of CTC in the blood of breast cancer patients. Both methylated DNA and CTC correlated with a more aggressive tumor biology and advanced disease.

Detection of circulating cancer cells using electrocatalytic gold nanoparticles

A rapid cancer cell detection and quantification assay, based on the electrocatalytic properties of gold nanoparticles towards the hydrogen evolution reaction, is described. The selective labeling of cancer cells is performed in suspension, allowing a fast interaction between the gold nanoparticle labels and the target proteins expressed at the cell membrane. The subsequent electrochemical detection is accomplished with small volumes of sample and user-friendly equipment through a simple electrochemical method that generates a fast electrochemical response used for the quantification of nanoparticle-labeled cancer cells. The system establishes a selective cell-detection assay capable of detecting 4 × 10(3) cancer cells in suspension that can be extended to several other cells detection scenarios.

Simultaneous, single particle, magnetization and size measurements of micron sized, magnetic particles

Single particle magnetization and size measurements of micron and nano sized, magnetic particles were made using a previously described device referred to as Cell Tracking Velocimetry, CTV. Three types of commercially available, and commonly used, magnetic particles were studied in this report. While the CTV instrument provides individual particles measurements, the average magnetization and size measurements were found to have reasonable agreements with reported values from instruments which measure bulk values. In addition, the CTV instrument, using electromagnets, can also determine magnetization curves, which also proved to have reasonable agreement with other published studies. Given that magnetic separation and analysis technology is dependent on the quality of the magnetic particles used, studies such as this one using CTV provide not only average data, but also provides information with respect to the distribution of the properties such as magnetization and size. For example, the spread of the data in magnetic and settling velocities were found to be predominately due to the size distribution of the analyzed particles.

Clinical implementation of comprehensive strategies to characterize cancer genomes: opportunities and challenges

An increasing number of anticancer therapeutic agents target specific mutant proteins that are expressed by many different tumor types. Recent evidence suggests that the selection of patients whose tumors harbor specific genetic alterations identifies the subset of patients who are most likely to benefit from the use of such agents. As the number of genetic alterations that provide diagnostic and/or therapeutic information increases, the comprehensive characterization of cancer genomes will be necessary to understand the spectrum of distinct genomic alterations in cancer, to identify patients who are likely to respond to particular therapies, and to facilitate the selection of treatment modalities. Rapid developments in new technologies for genomic analysis now provide the means to perform comprehensive analyses of cancer genomes. In this article, we review the current state of cancer genome analysis and discuss the challenges and opportunities necessary to implement these technologies in a clinical setting.

Capture, isolation and release of cancer cells with aptamer-functionalized glass bead array

Early detection and isolation of circulating tumor cells (CTC) can enable better prognosis for cancer patients. A Hele-Shaw device with aptamer functionalized glass beads is designed, modeled, and fabricated to efficiently isolate cancer cells from a cellular mixture. The glass beads are functionalized with anti-epidermal growth factor receptor (EGFR) aptamer and sit in ordered array of pits in polydimethylsiloxane (PDMS) channel. A PDMS encapsulation is then used to cover the channel and to flow through cell solution. The beads capture cancer cells from flowing solution depicting high selectivity. The cell-bound glass beads are then re-suspended from the device surface followed by the release of 92% cells from glass beads using combination of soft shaking and anti-sense RNA. This approach ensures that the cells remain in native state and undisturbed during capture, isolation and elution for post-analysis. The use of highly selective anti-EGFR aptamer with the glass beads in an array and subsequent release of cells with antisense molecules provide multiple levels of binding and release opportunities that can help in defining new classes of CTC enumeration devices.

Microsieve lab-chip device for rapid enumeration and fluorescence in situ hybridization of circulating tumor cells

Herein we present a lab-chip device for highly efficient and rapid detection of circulating tumor cells (CTCs) from whole blood samples. The device utilizes a microfabricated silicon microsieve with a densely packed pore array (10(5) pores per device) to rapidly separate tumor cells from whole blood, utilizing the size and deformability differences between the CTCs and normal blood cells. The whole process, including tumor cell capture, antibody staining, removal of unwanted contaminants and immunofluorescence imaging, was performed directly on the microsieve within an integrated microfluidic unit, interconnected to a peristaltic pump for fluid regulation and a fluorescence microscope for cell counting. The latter was equipped with a dedicated digital image processing program which was developed to automatically categorize the captured cells based on the immunofluorescence images. A high recovery rate of >80% was achieved with defined numbers of MCF-7 and HepG2 cancer cells spiked into human whole blood and filtered at a rapid flow rate of 1 mL min(-1). The device was further validated with blood drawn from various cancer patients (8 samples). The whole process, from sample input to result, was completed in 1.5 h. In addition, we have also successfully demonstrated on-microsieve fluorescence in situ hybridization for single cell molecular analysis. This simple method has great potential to supplant existing complex CTC detection schemes for cancer metastasis analysis.

Separation of cancer cells from a red blood cell suspension using inertial force

The circulating tumor cell (CTC) test has recently become popular for evaluating prognosis and treatment efficacy in cancer patients. The accuracy of the test is strongly dependent on the precision of the cancer cell separation. In this study, we developed a multistage microfluidic device to separate cancer cells from a red blood cell (RBC) suspension using inertial migration forces. The device was able to effectively remove RBCs up to the 1% hematocrit (Hct) condition with a throughput of 565 μL min(-1). The collection efficiency of cancer cells from a RBC suspension was about 85%, and the enrichment of cancer cells was about 120-fold. Further improvements can be easily achieved by parallelizing the device. These results illustrate that the separation of cancer cells from RBCs is possible using only inertial migration forces, thus paving the way for the development of a novel microfluidic device for future CTC tests.

Advancing personalized cancer medicine in lung cancer

Although improvements in genomic technologies during the past decade have greatly advanced our understanding of the genomic alterations that contribute to lung cancer, and the disease has (to a degree) become a paradigm for individualized cancer treatment in solid tumors, additional challenges must be addressed before the goal of personalized cancer therapy can become a reality for lung cancer patients.

ALK-gene rearrangement: a comparative analysis on circulating tumour cells and tumour tissue from patients with lung adenocarcinoma

BACKGROUND

A subgroup of anaplastic lymphoma kinase (ALK)-rearranged lung tumours can respond to ALK inhibitors. Until now, the ALK status in circulating tumour cells (CTCs) isolated from patients with lung cancer has not been characterised. We assessed the ALK status in CTCs detected in patients with lung cancer and correlated the results to the ALK status defined in the corresponding tumour tissue.

PATIENTS AND METHODS

A total of 87 patients with lung adenocarcinoma showing CTCs isolated using the isolation by size of epithelial tumour cell method were screened for their ALK status both in tumour samples and in CTCs. ALK break-apart fluorescence in situ hybridisation (FISH) and immunoreactivity analyses using an anti-ALK antibody (5A4 clone) were carried out on CTCs and compared with the results obtained in the corresponding tissue specimens.

RESULTS

A total of five patients showed ALK-gene rearrangement and strong ALK protein expression in CTCs and in the corresponding tumour samples. Both ALK-FISH and ALK immunoreactivity analyses show negative results in CTCs and corresponding tumour samples for 82 patients. Conclusions We demonstrated that the ALK status can be determined in CTCs isolated from patients with lung cancer by immunocytochemistry and FISH analyses. These results favour non-invasive, ALK-gene status pre-screening on a routine basis on CTCs isolated from patients with lung cancer and open new avenues for real-time monitoring for adapted targeted therapy.

An electrochemiluminescence strategy based on aptamers and nanoparticles for the detection of cancer cells

A PCR (polymerase chain reaction)-free electrochemiluminescence (ECL) strategy based on aptamers and ECL nanoprobes was developed for rapid collection and detection of Ramos cells. The ECL nanoprobes consisted of gold nanoparticles (AuNPs), linker DNA and tris-(2,2'-bipyridyl) ruthenium (TBR)-labeled signal DNA. The linker DNA and signal DNA were modified on the surface of the AuNPs through AuS bonds. The linker DNA can hybridize partly with the aptamers loaded on the magnetic beads to construct the magnetic biocomplex. In the presence of the cancer cells, the aptamers conjugated with the cancer cells with higher affinity. The ECL nanoprobe released from the biocomplex and subsequently hybridized with the capture DNA modified on the Au electrode. The ECL intensity of the TBR loaded on the nanoprobes directly reflected the amount of the cancer cells. With the use of the developed ECL probe, a limit of detection as low as 50 Ramos cells per mL could be achieved. The proposed methods based on ECL should have wide applications in the diagnosis of cancers due to their high sensitivity, simplicity and low cost.

Preventing postoperative metastatic disease by inhibiting surgery-induced dysfunction in natural killer cells

Natural killer (NK) cell clearance of tumor cell emboli following surgery is thought to be vital in preventing postoperative metastases. Using a mouse model of surgical stress, we transferred surgically stressed NK cells into NK-deficient mice and observed enhanced lung metastases in tumor-bearing mice as compared with mice that received untreated NK cells. These results establish that NK cells play a crucial role in mediating tumor clearance following surgery. Surgery markedly reduced NK cell total numbers in the spleen and affected NK cell migration. Ex vivo and in vivo tumor cell killing by NK cells were significantly reduced in surgically stressed mice. Furthermore, secreted tissue signals and myeloid-derived suppressor cell populations were altered in surgically stressed mice. Significantly, perioperative administration of oncolytic parapoxvirus ovis (ORFV) and vaccinia virus can reverse NK cell suppression, which correlates with a reduction in the postoperative formation of metastases. In human studies, postoperative cancer surgery patients had reduced NK cell cytotoxicity, and we show for the first time that oncolytic vaccinia virus markedly increases NK cell activity in patients with cancer. These data provide direct in vivo evidence that surgical stress impairs global NK cell function. Perioperative therapies aimed at enhancing NK cell function will reduce metastatic recurrence and improve survival in surgical cancer patients.

[Advances in research on circulating tumor cells in lung cancer]

转移和复发是肺癌患者死亡的主要原因。研究发现循环肿瘤细胞（circulating tumor cells, CTCs）在肺癌转移和复发中起着重要作用。而且随着靶向治疗的不断进步，对于晚期无法取得肺癌实体组织的患者，CTCs作为一种肺癌组织替代物可以决定治疗方案。所以CTCs在早期发现肺癌患者的微转移、检测肿瘤复发、评估预后和选择个体化治疗方案方面有着重要作用。本文针对CTCs的研究进展及肺癌领域的应用进行综述。

Molecular characterization of circulating tumor cells in patients with ovarian cancer improves their prognostic significance -- a study of the OVCAD consortium

OBJECTIVE

The study aims at identifying novel markers for circulating tumor cells (CTCs) in patients with epithelial ovarian cancer (EOC), and at evaluating their impact on outcome.

METHODS

Microarray analysis comparing matched EOC tissues and peripheral blood leucocytes (N=35) was performed to identify novel CTC markers. Gene expression of these novel markers and of EpCAM was analyzed using RT-qPCR in blood samples taken from healthy females (N=39) and from EOC patients (N=216) before primary treatment and six months after adjuvant chemotherapy. All samples were enriched by density gradient centrifugation. CTC positivity was defined by over-expression of at least one gene as compared to the healthy control group.

RESULTS

CTC were detected in 24.5% of the baseline and 20.4% of the follow-up samples, of which two thirds were identified by overexpression of the cyclophilin C gene (PPIC), and just a few by EpCAM overexpression. The presence of CTCs at baseline correlated with the presence of ascites, sub-optimal debulking, and elevated CA-125 and HE-4 levels, whereas CTC during follow-up occurred more often in older and platinum resistant patients. PPIC positive CTCs during follow-up were significantly more often detected in the platinum resistant than in the platinum sensitive patient group, and indicated poor outcome independent from classical prognostic parameters.

CONCLUSIONS

Molecular characterization of CTC is superior to a mere CTC enumeration or even be the rationale for CTC diagnostics at all. Ultimately CTC diagnostics may lead to more personalized treatment of EOC, especially in the recurrent situation.

Highly efficient assay of circulating tumor cells by selective sedimentation with a density gradient medium and microfiltration from whole blood

Isolation of circulating tumor cells (CTCs) by size exclusion can yield poor purity and low recovery rates, due to large variations in size of CTCs, which may overlap with leukocytes and render size-based filtration methods unreliable. This report presents a very sensitive, selective, fast, and novel method for isolation and detection of CTCs. Our assay platform consists of three steps: (i) capturing CTCs with anti-EpCAM conjugated microbeads, (ii) removal of unwanted hematologic cells (e.g., leukocytes, erythrocytes, etc.) by selective sedimentation of CTCs within a density gradient medium, and (iii) simple microfiltration to collect these cells. To demonstrate the efficacy of this assay, MCF-7 breast cancer cells (average diameter, 24 μm) and DMS-79 small cell lung cancer cells (average diameter, 10 μm) were used to model CTCs. We investigated the relative sedimentation rates for various cells and/or particles, such as CTCs conjugated with different types of microbeads, leukocytes, and erythrocytes, in order to maximize differences in the physical properties. We observed that greater than 99% of leukocytes in whole blood were effectively removed at an optimal centrifugal force, due to differences in their sedimentation rates, yielding a much purer sample compared to other filter-based methods. We also investigated not only the effect of filtration conditions on recovery rates and sample purity but also the sensitivity of our assay platform. Our results showed a near perfect recovery rate (~99%) for MCF-7 cells and very high recovery rate (~89%) for DMS-79 cells, with minimal amounts of leukocytes present.

SSA-MOA: a novel CTC isolation platform using selective size amplification (SSA) and a multi-obstacle architecture (MOA) filter

Circulating tumor cells (CTCs) have gained increasing attention as physicians and scientists learn more about the role these extraordinarily rare cells play in metastatic cancer. In developing CTC technology, the critical criteria are high recovery rates and high purity. Current isolation methods suffer from an inherent trade-off between these two goals. Moreover, ensuring minimal cell stress and robust reproducibility is also important for the clinical application of CTCs. In this paper, we introduce a novel CTC isolation technology using selective size amplification (SSA) for target cells and a multi-obstacle architecture (MOA) filter to overcome this trade-off, improving both recovery rate and purity. We also demonstrate SSA-MOA's advantages in minimizing cell deformation during filter transit, resulting in more stable and robust CTC isolation. In this technique, polymer microbeads conjugated with anti-epithelial cell adhesion molecules (anti-EpCAM) were used to selectively size-amplify MCF-7 breast cancer cells, definitively differentiating from the white blood cells (WBCs) by avoiding the size overlap that compromises other size selection methods. 3 μm was determined to be the optimal microbead diameter, not only for size discrimination but also in maximizing CTC surface coverage. A multi-obstacle architecture filter was fabricated using silicon-on-glass (SOG) technology-a first such application of this fabrication technique-to create a precise microfilter structure with a high aspect ratio. The filter was designed to minimize cell deformation as simulation results predicted that cells captured via this MOA filter would experience 22% less moving force than with a single-obstacle architecture. This was verified by experiments, as we observed reliable cell capture and reduced cell deformation, with a 92% average recovery rate and 351 peripheral blood leukocytes (PBL) per millilitre (average). We expect the SSA-MOA platform to optimize CTC recovery rates, purity, and stability, increasing the sensitivity and reliability of such tests, thereby potentially expanding the utilization of CTC technologies in the clinic.

A microfluidic-based device for study of transendothelial invasion of tumor aggregates in realtime

Circulating tumor aggregates exhibit a high metastatic potential and could potentially serve as an important target for cancer therapies. In this study, we developed a microfluidic model that reconstitutes and is representative of the principal components of biological blood vessels, including vessel cavity, endothelium, and perivascular matrix containing chemokines. Using this model, the transendothelial invasion of tumor aggregates can be observed and recorded in realtime. In this study we analyzed the extravasation process of salivary gland adenoid cystic carcinoma (ACC) cell aggregates. ACC aggregates transmigrated across the endothelium under the stimulation of chemokine CXCL12. The endothelial integrity was irreversibly damaged at the site of transendothelial invasion. The transendothelial invasion of ACC aggregates was inhibited by AMD3100, but the adhesion of ACC aggregates to the endothelium was not affected by the CXCR4 antagonist. This model allows for detailed study of the attachment and transendothelial invasion of tumor aggregates; thus, it would be a useful tool for analysis of the underlying mechanisms of metastasis and for testing novel anti-metastasis agents.

Progress in circulating tumor cell capture and analysis: implications for cancer management

The hematogenous dissemination of cancer and development of distant metastases is the cause of nearly all cancer deaths. Detection of circulating tumor cells (CTCs) as a surrogate biomarker of metastases has gained increasing interest. There is accumulating evidence on development of novel technologies for CTC detection, their prognostic relevance and their use in therapeutic response monitoring. Many clinical trials in the early and metastatic cancer setting, particularly in breast cancer, are including CTCs in their translational research programs and as secondary end points. We summarize the progress of detection methods in the context of their clinical importance and speculate on the possibilities of wider implementation of CTCs as a diagnostic oncology tool, the likelihood that CTCs will be used as a useful biomarker, especially to monitor therapeutic response, and what may be expected from the future improvements in technologies.

Using circulating tumor cells as a prognostic indicator in metastatic castration-resistant prostate cancer

A more reliable tumor marker is needed as a prognostic indicator in metastatic castration-resistant prostate cancer. Circulating tumor cells (CTCs) are cells that have broken away from a tumor and flow in the bloodstream. Evidence has indicated that the presence of CTCs in the peripheral blood of men with solid malignancies correlates with clinical outcomes. When the CTC number is reduced to fewer than five cells per 7.5 ml of blood, survival outcomes often improve. The relationship between the number of CTCs and prognosis has the potential to influence treatment decisions. Therefore, oncology nurses and practitioners must evaluate the scientific evidence, understand the clinical implications, and realize the impact CTC counts may have on practice to effectively communicate the CTC results to a patient. In addition, oncology nurses and practitioners must know that although favorable changes in CTC count are associated with a better prognosis, that alone cannot be used to guide treatment decisions for an individual.

Molecular markers in peripheral blood of Iranian women with breast cancer

A biomarker is a quantifiable laboratory measure of a disease specific biologically relevant molecule that can act as an indicator of a current or future disease state. The purpose of this study is to detect the expression of RNA biomarkers using Cytokeratin 19 (CK-19), Mammaglobin (MAM), Carcinoembryonic antigen (CEA), Mucin (MUC), C-Myc, erb-B2, a proliferation marker (Ki-67), Epidermal growth factor receptor (Her2/neu) and Estrogen receptor (ER) in Iranian women who were diagnosed with breast cancer. In this study, 90 samples; 60 cancer patients and 30 healthy controls were considered. 73.4 % patients were in stage I/II and 26.6 % were in stage III/IV. Patients were selected prior to the administration of any adjuvant systemic therapy. Total RNA extraction was obtained from peripheral blood of each patient and healthy control. Reverse transcription polymerase chain reaction (RT-PCR) method was used for detection of mRNA of the selected biomarkers of circulating breast cancer cells in blood. Molecular characterization is assessed as a method for early detection of breast cancer. For this purpose, eleven specific primers were selected and RT-PCR was used. The data of RT-PCR revealed that expression of MUC1, CK19, CEA, MAM, erbB-2, Ki67 and C-Myc biomarkers were significantly different between breast cancer patients and healthy controls. On the other hand, ERα, ERβ and Her2 markers were not significantly different between the two mentioned groups. Biomarkers detection of breast cancer patients could be assessed as a diagnostic factor and its potential for conveying as a prognostic factor require further studies, with a larger number of patients.

A novel method for the in vivo isolation of circulating tumor cells from peripheral blood of cancer patients using a functionalized and structured medical wire

The isolation of circulating tumor cells (CTCs) from the blood of patients afflicted with solid malignant tumors becomes increasingly important as it may serve as a 'liquid biopsy' with the potential of monitoring the course of the cancer disease and its response to cancer therapy, with subsequent molecular characterization. For this purpose, we functionalized a structured medical Seldinger guidewire (FSMW), normally used to obtain safe access to blood vessels and other organ cavities, with a chimeric monoclonal antibody directed to the cell surface expressed epithelial cell surface adhesion molecule (EpCAM). This medical device was optimized in vitro and its biocompatibility was tested according to the regulations for medical devices and found to be safe with no noteworthy side effects. Suitability, specificity and sensitivity of the FSMW to catch and enrich CTCs in vivo from circulating peripheral blood were tested in 24 breast cancer or non-small cell lung cancer (NSCLC) patients and in 29 healthy volunteers. For this, the FSMW was inserted through a standard venous cannula into the cubital veins of healthy volunteers or cancer patients for the duration of 30 min. After removal, CTCs were identified by immuno-cytochemical staining of EpCAM and/or cytokeratins and staining of their nuclei and counted. The FSMW successfully enriched EpCAM-positive CTCs from 22 of the 24 patients, with a median of 5.5 (0-50) CTCs in breast cancer (n=12) and 16 (2-515) CTCs in NSCLC (n=12). CTCs could be isolated across all tumor stages, including early stage cancer, in which distant metastases were not yet diagnosed, while no CTCs could be detected in healthy volunteers. In this observatory study, no adverse effects were noted. Evidently, the FSMW has the potential to become an important device to enrich CTCs in vivo for monitoring the course of the cancer disease and the efficacy of anticancer treatment.

Stem cells as a tool for breast imaging

Stem cells are a scientific field of interest due to their therapeutic potential. There are different groups, depending on the differentiation state. We can find lonely stem cells, but generally they distribute in niches. Stem cells don't survive forever. They are affected for senescence. Cancer stem cells are best defined functionally, as a subpopulation of tumor cells that can enrich for tumorigenic property and can regenerate heterogeneity of the original tumor. Circulating tumor cells are cells that have detached from a primary tumor and circulate in the bloodstream. They may constitute seeds for subsequent growth of additional tumors (metastasis) in different tissues. Advances in molecular imaging have allowed a deeper understanding of the in vivo behavior of stem cells and have proven to be indispensable in preclinical and clinical studies. One of the first imaging modalities for monitoring pluripotent stem cells in vivo, magnetic resonance imaging (MRI) offers high spatial and temporal resolution to obtain detailed morphological and functional information. Advantages of radioscintigraphic techniques include their picomolar sensitivity, good tissue penetration, and translation to clinical applications. Radionuclide imaging is the sole direct labeling technique used thus far in human studies, involving both autologous bone marrow derived and peripheral stem cells.

Cell separation based on size and deformability using microfluidic funnel ratchets

The separation of biological cells by filtration through microstructured constrictions is limited by unpredictable variations of the filter hydrodynamic resistance as cells accumulate in the microstructure. Applying a reverse flow to unclog the filter will undo the separation and reduce filter selectivity because of the reversibility of low-Reynolds number flow. We introduce a microfluidic structural ratchet mechanism to separate cells using oscillatory flow. Using model cells and microparticles, we confirmed the ability of this mechanism to sort and separate cells and particles based on size and deformability. We further demonstrate that the spatial distribution of cells after sorting is repeatable and that the separation process is irreversible. This mechanism can be applied generally to separate cells that differ based on size and deformability.

Single-domain antibodies: a versatile and rich source of binders for breast cancer diagnostic approaches

Noninvasive early detection of breast cancer through the use of biomarkers is urgently needed since the risk of recurrence, morbidity, and mortality is closely related to disease stage at the time of primary surgery. A crucial issue in this approach is the availability of relevant markers and corresponding monoclonal antibodies suitable for the development of effective immunodiagnostic modalities. The identification of such markers from human pathological lesions and the isolation of specific antibodies using conventional approaches remain major challenges. Camelids produce functional antibodies devoid of light chains in which the single N-terminal domain of the heavy chain is fully capable of antigen binding. When produced as an independent domain, these so-called single-domain antibody fragments (sdAbs) or nanobodies have several advantages for biotechnological applications owing to their unique properties of size (13 kDa), stability, solubility, and expression yield. In this work, we have generated phage display libraries from animals immunized with breast cancer biopsies. These libraries were used to isolate sdAbs against known and relevant antigens such as HER2, or several cancer-specific sdAbs against unknown targets. We describe the identification of one these targets, cytokeratin 19, using affinity purification in combination with mass spectrometry. Some of these sdAbs were used in several straightforward diagnostic applications such as immunohistochemical analysis of tumor samples, multiplexed cytometric bead array analysis of crude samples, or an immune enrichment procedure of rare cells. Here, we demonstrate that phage display-based selection of single-domain antibodies is an efficient and high-throughput compatible approach to generate binders with excellent characteristics for the fast development of diagnostic and prognostic modalities.

Albumin-coated monodisperse magnetic poly(glycidyl methacrylate) microspheres with immobilized antibodies: application to the capture of epithelial cancer cells

Monodisperse (4 μm) macroporous crosslinked poly(glycidyl methacrylate) (PGMA) microspheres for use in microfluidic immunomagnetic cell sorting, with a specific application to the capture of circulating tumor cells (CTCs), were prepared by multistep swelling polymerization in the presence of cyclohexyl acetate porogen and hydrolyzed and ammonolyzed. Iron oxide was then precipitated in the microspheres to render them magnetic. Repeated precipitation made possible to raise the iron oxide content to more than 30 wt %. To minimize nonspecific adsorption of the microspheres in a microchannel and of cells on the microspheres, they were coated with albumin crosslinked with glutaraldehyde. Antibodies of epithelial cell adhesion molecule (anti-EpCAM) were then immobilized on the albumin-coated magnetic microspheres using the carbodiimide method. Capture of breast cancer MCF7 cells as a model of CTCs by the microspheres with immobilized anti-EpCAM IgG was performed in a batch experiment. Finally, MCF7 cells were captured by the anti-EpCAM-immobilized albumin-coated magnetic microspheres in an Ephesia chip. A very good rejection of lymphocytes was achieved. Thus, albumin-coated monodisperse magnetic PGMA microspheres with immobilized anti-EpCAM seem to be promising for capture of CTCs in a microfluidic device.

Microfluidic cell sorter (μFCS) for on-chip capture and analysis of single cells

A low-cost and rapid microfluidic cell sorter (μFCS) for circulating tumor cell (CTC) detection, culture and analyses is developed. Based on size separation and molecular characterization, μFCS efficiently enriches CTCs from unprocessed whole blood, allows on-chip culture and molecular profiling, and provides cell retrieval for subsequent analyses. The potential clinical application of the technology is demonstrated by capturing and genetically analyzing CTCs in tumor-bearing mice.

Monitoring of the generation of circulating tumor cells in central venous blood of patients undergoing right hepatectomy using anterior liver hanging maneuver

AIM: To monitor the generation of circulating tumor cells in central venous blood of patients undergoing right hepatectomy using anterior liver hanging (ALH) maneuver.

METHODS: From January 2008 to June 2011, 40 patients undergoing right hepatectomy were randomly allocated to ALH and conventional approach (CA) groups. Blood samples were collected from all patients through a central venous catheter, just before skin incision, just before parenchymal transection (after hilar dissection in the ALH group and after mobilization of the liver in the CA group), and after delivery of the tumor. All samples were detected for CTCs using an asialoglycoprotein receptor-based isolation strategy. The proportions of CTC-positive patients at various stages of surgery were compared between the two groups.

RESULTS: The proportion of CTC-positive patients showed no significant difference before surgery between the two groups (2/18 vs 1/19, P > 0.05) but was significantly lower in the ALH group than in the CA group before parenchymal transection and at the end of surgery after delivery of the tumor (20% vs 55%, 40% vs 80%, P = 0.022, 0.010).

CONCLUSION: Right hepatectomy using anterior liver hanging maneuver can reduce intraoperative blood-borne spread of tumor cells compared with the conventional method.

Microtube Device for Selectin-Mediated Capture of Viable Circulating Tumor Cells from Blood

BACKGROUND

Circulating tumor cells (CTCs) can be used clinically to treat cancer. As a diagnostic tool, the CTC count can be used to follow disease progression, and as a treatment tool, CTCs can be used to rapidly develop personalized therapeutic strategies. To be effectively used, however, CTCs must be isolated at high purity without inflicting cellular damage.

METHODS

We designed a microscale flow device with a functionalized surface of E-selectin and antibody molecules against epithelial markers. The device was additionally enhanced with a halloysite nanotube coating. We created model samples in which a known number of labeled cancer cells were suspended in healthy whole blood to determine device capture efficiency. We then isolated and cultured primary CTCs from buffy coat samples of patients diagnosed with metastatic cancer.

RESULTS

Approximately 50% of CTCs were captured from model samples. Samples from 12 metastatic cancer patients and 8 healthy participants were processed in nanotube-coated or smooth devices to isolate CTCs. We isolated 20–704 viable CTCs per 3.75-mL sample, achieving purities of 18%–80% CTCs. The nanotube-coated surface significantly improved capture purities (P = 0.0004). Experiments suggested that this increase in purity was due to suppression of leukocyte spreading.

CONCLUSIONS

The device successfully isolates viable CTCs from both blood and buffy coat samples. The approximately 50% capture rate with purities >50% with the nanotube coating demonstrates the functionality of this device in a clinical setting and opens the door for personalized cancer therapies.

Molecular biology techniques for the surgeon

New technologies are constantly being introduced into the medical and surgical fields. These technologies come in the form of newer medicines, imaging methods and prognostic tools, among others, and allow clinicians to make more rational and informed decisions on the care of their patients. Many of these technologies utilize advanced techniques which are at the forefront of many research fields and represent a transition of bench advances into the clinical realm. This review will highlight four technologies that are at the forefront in the treatment of oncology patients treated by surgeons on a daily basis. Circulating tumor cells, microarray analysis, proteomic studies and rapid sequencing technologies will be highlighted. These technologies will be reviewed and their potential use in the care of surgical patients will be discussed.

A stochastic Markov chain model to describe lung cancer growth and metastasis

A stochastic Markov chain model for metastatic progression is developed for primary lung cancer based on a network construction of metastatic sites with dynamics modeled as an ensemble of random walkers on the network. We calculate a transition matrix, with entries (transition probabilities) interpreted as random variables, and use it to construct a circular bi-directional network of primary and metastatic locations based on postmortem tissue analysis of 3827 autopsies on untreated patients documenting all primary tumor locations and metastatic sites from this population. The resulting 50 potential metastatic sites are connected by directed edges with distributed weightings, where the site connections and weightings are obtained by calculating the entries of an ensemble of transition matrices so that the steady-state distribution obtained from the long-time limit of the Markov chain dynamical system corresponds to the ensemble metastatic distribution obtained from the autopsy data set. We condition our search for a transition matrix on an initial distribution of metastatic tumors obtained from the data set. Through an iterative numerical search procedure, we adjust the entries of a sequence of approximations until a transition matrix with the correct steady-state is found (up to a numerical threshold). Since this constrained linear optimization problem is underdetermined, we characterize the statistical variance of the ensemble of transition matrices calculated using the means and variances of their singular value distributions as a diagnostic tool. We interpret the ensemble averaged transition probabilities as (approximately) normally distributed random variables. The model allows us to simulate and quantify disease progression pathways and timescales of progression from the lung position to other sites and we highlight several key findings based on the model.

Electrochemiluminescent determination of cancer cells based on aptamers, nanoparticles, and magnetic beads

Herein we report a polymerase chain reaction (PCR)-free electrochemiluminescence (ECL) approach that uses ECL nanoprobes for the determination of cancer cells with high sensitivity. The ECL nanoprobe consists of gold nanoparticles (AuNPs), linker DNA, and tris(2,2'-bipyridyl)ruthenium (TBR)-labeled signal DNA. The linker DNA and signal DNA were modified on the surface of the AuNPs through Au-S bonds. The linker DNA can partly hybridize with the aptamers of cancer cells loaded onto the magnetic beads (MB1) to construct the magnetic biocomplexes. In the presence of the cancer cells, the aptamers conjugated with the cancer cells with higher affinity. The ECL nanoprobe was released from the biocomplexes and subsequently hybridized with the capture DNA loaded onto another magnetic bead (MB2) to form the magnetic nanocomposite. The nanocomposites can be easily separated and firmly attached to an electrode on account of their excellent magnetic properties. The ECL intensity of the TBR loaded onto the nanocomposites directly reflected the amount of cancer cells. By using cell lines of Burkitt's lymphoma (Ramos cells) as a model, the ECL response was proportional to the cell concentration in the range from 5 to 100 cells ml(-1); a limit of detection as low as 5 cells ml(-1) of Ramos cells could be achieved. The proposed method described here is ideal for the diagnosis of cancers due to its high sensitivity, simplicity, and low cost.

Channel surface patterning of alternating biomimetic protein combinations for enhanced microfluidic tumor cell isolation

Here, we report a new method for multicomponent protein patterning in a microchannel and also a technique for improving immunoaffinity-based circulating tumor cell (CTC) capture by patterning regions of alternating adhesive proteins using the new method. The first of two proteins, antiepithelial cell adhesion molecule (anti-EpCAM), provides the specificity for CTC capture. The second, E-selectin, increases CTC capture under shear. Patterning regions with and without E-selectin allows captured leukocytes, which also bind E-selectin and are unwanted impurities in CTC isolation, to roll a short distance and detach from the capture surface. This reduces leukocyte capture by up to 82%. The patterning is combined with a leukocyte elution step in which a calcium chelating buffer effectively deactivates E-selectin so that leukocytes may be rinsed away 60% more efficiently than with a buffer containing calcium. The alternating patterning of this biomimetic protein combination, used in conjunction with the elution step, reduces capture of leukocytes while maintaining a high tumor cell capture efficiency that is up to 1.9 times higher than the tumor cell capture efficiency of a surface with only anti-EpCAM. The new patterning technique described here does not require mask alignment and can be used to spatially control the immobilization of any two proteins or protein mixtures inside a sealed microfluidic channel.

Cascade signal amplification strategy for the detection of cancer cells by rolling circle amplification and nanoparticles tagging

A cascade signal amplification strategy was proposed for detection of cancer cells at ultralow concentration by combining the rolling circle amplification (RCA) technique with oligonucleotide functionalized nanoparticles (NPs), and anodic stripping voltammetric detection. This flexible biosensing system exhibited high sensitivity and specificity with the detection limits of 10 Ramos cells mL(-1).

Tumor cell and carcinoma-associated fibroblast interaction regulates matrix metalloproteinases and their inhibitors in oral squamous cell carcinoma

Co-culture of periodontal ligament (PDL) fibroblasts and SCC-25 oral squamous carcinoma cells (OSCC), results in conversion of PDLs into carcinoma-associated fibroblasts (CAFs). Paracrin circuits between CAFs and OSCC cells were hypothesized to regulate the gene expression of matrix remodeling enzymes in their co-culture, which was performed for 7days, followed by analysis of the mRNA/protein expression and activity of metalloproteinases (MMPs), their tissue inhibitors (TIMPs) and other relevant genes. Interleukin1-β, transforming growth factor-β1, fibronectin and αvβ6 integrin have shown to be involved in the regulation of the MMP and TIMP gene expression in co-culture of CAFs and tumor cells. In addition, these cells also cooperated in activation of MMP pro-enzymes. It is particularly interesting that the fibroblast-produced inactive MMP-2 has been activated by the tumor-cell-produced membrane-type 1 matrix metalloproteinase (MT1-MMP). The crosstalk between cancer- and the surrounding fibroblast stromal-cells is essential for the fine tuning of cancer cells invasivity.

Identification and enumeration of circulating tumor cells in the cerebrospinal fluid of breast cancer patients with central nervous system metastases

The number of circulating tumor cells (CTCs) in the peripheral blood of metastatic breast cancer patients is now an established prognostic marker. While the central nervous system is a common site of metastasis in breast cancer, the standard marker for disease progression in this setting is cerebrospinal fluid (CSF) cytology. However, the significance of CSF cytology is unclear, requires large sample size, is insensitive and subjective, and sometimes yields equivocal results. Here, we report the detection of breast cancer cells in CSF using molecular markers by adapting the CellSearch system (Veridex). We used this platform to isolate and enumerate breast cancer cells in CSF of breast cancer patients with central nervous system (CNS) metastases. The number of CSF tumor cells correlated with tumor response to chemotherapy and were dynamically associated with disease burden. This CSF tumor cell detection method provides a semi-automated molecular analysis that vastly improves the sensitivity, reliability, objectivity, and accuracy of detecting CSF tumor cells compared to CSF cytology. CSF tumor cells may serve as a marker of disease progression and early-stage brain metastasis in breast cancer and potentiate further molecular analysis to elucidate the biology and significance of tumor cells in the CSF.