Tumor cells, rather than dendritic cells, deliver antigen to the lymph node for cross-presentation

It is widely accepted that generation of tumor specific CD8+ T-cell responses occur via cross-priming; however the source of tumor antigen for this event is unknown. We examined the source and form of tumor antigen required for cross-presentation in the local lymph node (LN) using a syngeneic mouse tumor model expressing a marker antigen. We found that cross-presentation of this model tumor antigen in the LN is dependent on continuous traffic of antigen from the tumor site, but without any detectable migration of tumor resident dendritic cells (DCs). Instead, small numbers of tumor cells metastasize to local LNs where they are exposed to a localized CTL attack, resulting in delivery of tumor antigen into the cross-presentation pathway.

Nanoscale metal-organic frameworks in detecting cancer biomarkers

Following the efficient performance of metal-organic frameworks (MOFs) as recognition elements in gas sensors, biosensors based on MOFs are now being investigated to capture and quantify potential cancer biomarkers, such as circulating tumor cells (CTCs), nucleic acids and proteins. The current status of MOF-based biosensors in the detection of early stages of cancer is in its infancy, although it has significantly emerged since the beginning of this decade. That said, salient research has been conducted in the past five years to utilize the distinctive porous crystalline structure of MOFs for highly sensitive and selective detection of cancer biomarkers. In this pursual, MOFs designed with bimetallic assembly, doped with magnetic nanoparticles, coated with polymers, and even conjugated with peptides or oligonucleotides have shown promising outcomes in detecting CTCs, nucleic acids and proteins. In particular, aptamer-conjugated MOFs are able to perform at a lower limit of detection down to the femtomolar, implying their efficacy for the point of care testing in clinical trials. In this way, aptasensors based on aptamer-conjugated MOFs present a newer sub-branch, to be coined as a MOFTA sensor in the current review. Considering the emerging progress and promising outcomes of MOFTA sensors as well as a variety of MOF-based techniques of detecting cancer biomarkers, this review will highlight their significant advances and related aspects in the recent five years on the context of detecting CTCs, nucleic acids and proteins for the early-stage detection of cancer.

Prognostic and therapeutic significance of circulating tumor cells in patients with lung cancer

BACKGROUND

Lung cancer is the second most common cancer and the main cause of cancer-related mortality worldwide. In spite of various efforts that have been made to facilitate the early diagnosis of lung cancer, most patients are diagnosed when the disease is already in stage IV, which is generally associated with the occurrence of distant metastases and a poor survival. Moreover, a large proportion of these patients will relapse after treatment, heralding the need for the stratification of lung cancer patients in addition to identifying those who are at a higher risk of relapse and, thus, require alternative and/or additional therapies. Recently, circulating tumor cells (CTCs) have been considered as valuable markers for the early diagnosis, prognosis and risk stratification of cancer patients, and they have been found to be able to predict the survival of patients with various types of cancer, including lung cancer. Additionally, the characterization of CTCs has recently provided fascinating insights into the heterogeneity of tumors, which may be instrumental for the development of novel targeted therapies.

CONCLUSIONS

Here we review our current understanding of the significance of CTCs in lung cancer metastasis. We also discuss prominent studies reporting the utility of enumeration and characterization of CTCs in lung cancer patients as prognostic and pharmacodynamic biomarkers for those who are at a higher risk of metastasis and drug resistance.

CTCs Expression Profiling for Advanced Breast Cancer Monitoring

The study of circulating tumor cells (CTCs) has a huge clinical interest in advance and metastatic breast cancer patients. However, many approaches are biased by the use of epithelial markers, which underestimate non-epithelial CTCs phenotypes. CTCs enumeration provides valuable prognostic information; however, molecular characterization could be the best option to monitor patients throughout the disease since it may provide more relevant clinical information to the physicians. In this work, we aimed at enumerating and performing a molecular characterization of CTCs from a cohort of 20 patients with metastatic breast cancer (MBC), monitoring the disease at different time points of the therapy, and at progression when it occurred. To this end, we used a CTC negative enrichment protocol that allowed us to recover a higher variety of CTCs phenotypes. With this strategy, we were able to obtain gene expression data from CTCs from all the patients. In addition, we found that high expression levels of PALB2 and MYC were associated with a worse outcome. Interestingly, we identified that CTCs with an EpCAM^highVIM^lowALDH1A1^high signature showed both shorter overall survival (OS) and progression-free survival (PFS), suggesting that CTCs with epithelial-stem features had the most aggressive phenotype.

A hybridization chain reaction based assay for fluorometric determination of exosomes using magnetic nanoparticles and both aptamers and antibody as recognition elements

Exosomes represent a new generation of biomarkers for the early diagnosis of hepatic carcinoma. A fluorometric assay is presented that is based on the hybridization chain reaction and magnetic nanoparticles for the highly sensitive determination of exosome (from HepG2 cells). Antibody as the recognition element was modified on the surface of magnetic nanoparticles. Antibody was used to capture the exosome. The Probe 1 was consisted of aptamer sequence and trigger sequence. Aptamer sequence will bind with the surface protein of exosome. The trigger sequence will hybridize with the probe2 (FAM-labeled) and the probe3 (FAM-labeled). So the product of the hybridization chain reaction will present a strong fluorescence signal. The fluorescence product of hybridization chain reaction will link with magnetic nanoparticles through the 'magnetic nanoparticles-antibody-exosome-aptamer' structure. The product can be separated from the matrix due to the present of the magnetic nanoparticles. The excitation was set at 490 nm. The fluorescence value of the emission spectra at 519 nm was set as the signal response. The linear range of this assay is from 1000 to 10⁷ particles·mL^-1. The detection limit is 100 particles·mL^-1. This assay was applied to the determination of exosome from the hepatic carcinoma cells. Graphical abstractIn the presence of exosmes, the hybridization chain reaction was triggered and strong green fluorescence will be produced. Moreover, the magnetic particles can separate the products from the matrix.

Clinical significance of detecting circulating tumor cells in patients with esophageal squamous cell carcinoma by EpCAM‑independent enrichment and immunostaining‑fluorescence in situ hybridization

Circulating tumor cells (CTCs) are tumor cells present in the bloodstream, which originate from tumor sites, and are ultimately responsible for metastasis or relapse in several types of cancer. However, to the best of our knowledge, only a few studies have investigated these extremely rare cells in esophageal squamous cell carcinoma (ESCC). In the present study, 63 patients with ESCC and 50 healthy donors were recruited, and the potential clinical significance of CTCs was assessed using subtraction enrichment and immunostaining‑fluorescence in situ hybridization. Blood samples were collected at the following times: At first diagnosis, following neoadjuvant chemoradiotherapy, 24 h and 13 days post‑surgery, and every 3 months during follow‑up. Cytokeratin (CK)‑positive and clustered CTCs only accounted for 1% of total CTCs detected, whereas most CTCs were CK‑negative aneuploid cells. Patients with ESCC (n=63) had higher CTC counts compared with healthy donors (control group; n=50) (area under curve=0.807, median CTC count, 2 vs. 0). However, there was no statistical association between CTC counts and sex, age, pathological stage, tumor location, tumor depth or lymph node involvement (P>0.05). The association of tumor development with CTC status and other circulating biomarkers was monitored in patients for a further 2 years. The results revealed that a change in CTC counts between first diagnosis and 13 days post‑surgery (ΔCTC) of ≥2/7.5 ml peripheral blood could be applied for predicting progression‑free survival (hazard ratio, 3.922; 95% confidence interval, 0.907‑16.951; P<0.05) in patients with ESCC. In conclusion, ΔCTC evaluation may be a promising indicator for predicting tumor prognosis and the clinical efficacy of treatment in patients with ESCC.

Current status of prognostic factors in patients with metastatic renal cell carcinoma

In recent years, the induction of novel agents, including molecular-targeted agents and immune checkpoint inhibitors, have dramatically changed therapeutic options and their outcomes for metastatic renal cell carcinoma. Several prognostic models based on the data of patients with metastatic renal cell carcinoma treated with targeted agents or cytokine therapy have been useful in real clinical practice. Serum or peripheral blood markers related to inflammatory response have been reported to be associated with their prognosis or therapeutic efficacy. In addition to them, investigation for novel predictive factors that represent the efficacy of agents, the risk of adverse events and the prognosis are required for the advance of therapeutic strategies. The present review discusses the conventional prognostic models and clinical factors, and recent advances of the identification of some of the most promising molecules as novel biomarkers for metastatic renal cell carcinoma.

Application of Circulation Tumor Cells Detection in Diagnosis and Treatment of Breast Tumors

In recent years, the clinical application of circulating tumor cell (CTCs) detection has become one of the research hotspots in the field of precision medicine. CTCs detection is noninvasive, easy to obtain, can be repeatedly collected, and highly repeatable with other advantages. It not only can be a real-time comprehensive monitoring of cancer treatment but also can have a large number of applications, including early diagnosis of tumor, timely evaluation of efficacy, condition monitoring, resistance factor analysis, prognosis judgment, individualized treatment of tumors, drug guidance, and so on. At present, many large-scale clinical studies at home and abroad run through all stages of breast cancer diagnosis and treatment. For different treatment stages of breast cancer, the application value of CTCs detection is different. Compared with traditional detection methods, CTCs have advantages in dynamic monitoring of disease changes and efficacy evaluation in real-time. In the era of breast cancer classificational and individualized treatment, CTCs detection can provide patients with the most timely and optimized treatment plan.

Comparison of analytic performances of Cellsearch and iFISH approach in detecting circulating tumor cells

Circulating tumor cells (CTCs) have been widely used to predict the prognosis of breast cancer patients. The aim of the present study was to compare the performances of Cellsearch and immunostaining-fluorescence in situ hybridization (iFISH) in detecting CTCs in breast cancer patients. Forty-five newly diagnosed breast cancer patients and 14 healthy donors were recruited and their CTCs were detected by both Cellsearch and iFISH. Correlation between clinicopathological features and CTCs was investigated. We found that the positive rate of CTC detected by iFISH was significantly higher than by Cellsearch system (91% vs 38%). The CTC count, detected either by iFISH or Cellsearch, was not significantly associated with clinical pictures of patients with breast cancer. Therefore, we concluded that, compared to conventional Cellsearch CTC detection, in situ karyotypic identification performed by iFISH had higher detection rate. Therefore, iFISH may be more clinically useful than Cellsearch system.

Full-angle tomographic phase microscopy of flowing quasi-spherical cells

We report a reliable full-angle tomographic phase microscopy (FA-TPM) method for flowing quasi-spherical cells along microfluidic channels. This method lies in a completely passive optical system, i.e. mechanical scanning or multi-direction probing of the sample is avoided. It exploits the engineered rolling of cells while they are flowing along a microfluidic channel. Here we demonstrate significant progress with respect to the state of the art of in-flow TPM by showing a general extension to cells having almost spherical shapes while they are flowing in suspension. In fact, the adopted strategy allows the accurate retrieval of rotation angles through a theoretical model of the cells' rotation in a dynamic microfluidic flow by matching it with phase-contrast images resulting from holographic reconstructions. So far, the proposed method is the first and the only one that permits to get in-flow TPM by probing the cells with full-angle, achieving accurate 3D refractive index mapping and the simplest optical setup, simultaneously. Proof of concept experiments were performed successfully on human breast adenocarcinoma MCF-7 cells, opening the way for the full characterization of circulating tumor cells (CTCs) in the new paradigm of liquid biopsy.

Circulating tumor cells and serum levels of MMP-2, MMP-9 and VEGF as markers of the metastatic process in patients with high risk of metastatic progression

BACKGROUND AND AIMS

Metastases are a severe complication in cancer patients and biomarkers predicting their progression are still lacking for specific groups of patients. HER2 positive breast cancer (HER2 BC) patients on trastuzumab therapy are at risk of the development of unpredictable and often fatal central nervous system (CNS) metastases and castration resistant prostate cancer (CRPC) patients urgently need a marker of disease progression during therapy. Proposed metastatic markers: circulating tumor cells (CTC), serum levels of matrix metalloproteinase 2 (MMP-2), 9 (MMP-9) and vascular endothelial growth factor (VEGF) were prospectively studied to confirm their utility in these two narrowly defined groups of cancer patients.

PATIENTS AND METHODS

The groups comprised 44 advanced HER2 BC, 24 CRPC patients and 42 healthy controls. An immunomagnetic separation method followed by PCR and electrophoretic detection (AdnaGen, Germany) were used for CTC determination. Serum marker levels were determined by the ELISAs (R&D System, USA).

RESULTS

MMP-2 serum level was significantly higher in HER2 BC patients who developed CNS metastases, especially if there were also bone metastases. CTCs were a negative predictive marker for overall survival in HER2 BC patients. MMP-9 serum level was significantly higher in CRPC patients in whom disease progression occurred. CTC vanished from the blood of most of the CRPC patients (from 88% to 37%) during chemotherapy.

CONCLUSION

MMP-2 serum level and CTCs show the potential to predict CNS metastases and overall survival in BC patients. CTCs and MMP-9 serum level could be a promising therapy response marker in CRPC patients.

EGFR-Based Immunoisolation as a Recovery Target for Low-EpCAM CTC Subpopulation

Circulating tumour cells (CTCs) play a key role in the metastasis process, as they are responsible for micrometastasis and are a valuable tool for monitoring patients in real-time. Moreover, efforts to develop new strategies for CTCs isolation and characterisation, and the translation of CTCs into clinical practice needs to overcome the limitation associated with the sole use of Epithelial Cell Adhesion Molecule (EpCAM) expression to purify this tumour cell subpopulation. CTCs are rare events in the blood of patients and are believed to represent the epithelial population from a primary tumour of epithelial origin, thus EpCAM immunoisolation is considered an appropriate strategy. The controversy stems from the impact that the more aggressive mesenchymal tumour phenotypes might have on the whole CTC population. In this work, we first characterised a panel of cell lines representative of tumour heterogeneity, confirming the existence of tumour cell subpopulations with restricted epithelial features and supporting the limitations of EpCAM-based technologies. We next developed customised polystyrene magnetic beads coated with antibodies to efficiently isolate the phenotypically different subpopulations of CTCs from the peripheral blood mononuclear cells (PBMCs) of patients with metastatic cancer. Besides EpCAM, we propose Epidermal Growth Factor Receptor (EGFR) as an additional isolation marker for efficient CTCs detection.

Circulating Tumor Cell Composition in Renal Cell Carcinoma

Purpose

Due to their minimal-invasive yet potentially current character circulating tumor cells (CTC) might be useful as a “liquid biopsy” in solid tumors. However, successful application in metastatic renal cell carcinoma (mRCC) has been very limited so far. High plasticity and heterogeneity of CTC morphology challenges currently available enrichment and detection techniques with EpCAM as the usual surface marker being underrepresented in mRCC. We recently described a method that enables us to identify and characterize non-hematopoietic cells in the peripheral blood stream with varying characteristics and define CTC subgroups that distinctly associate to clinical parameters. With this pilot study we wanted to scrutinize feasibility of this approach and its potential usage in clinical studies.

Experimental Design

Peripheral blood was drawn from 14 consecutive mRCC patients at the West German Cancer Center and CTC profiles were analyzed by Multi-Parameter Immunofluorescence Microscopy (MPIM). Additionally angiogenesis-related genes were measured by quantitative RT-PCR analysis.

Results

We detected CTC with epithelial, mesenchymal, stem cell-like or mixed-cell characteristics at different time-points during anti-angiogenic therapy. The presence and quantity of N-cadherin-positive or CD133-positive CTC was associated with inferior PFS. There was an inverse correlation between high expression of HIF1A, VEGFA, VEGFR and FGFR and the presence of N-cadherin-positive and CD133-positive CTC.

Conclusions

Patients with mRCC exhibit distinct CTC profiles that may implicate differences in therapeutic outcome. Prospective evaluation of phenotypic and genetic CTC profiling as prognostic and predictive biomarker in mRCC is warranted.

Precision Microfilters as an all in one System for Multiplex Analysis of Circulating Tumor Cells

Enumeration of circulating tumor cells (CTCs) from cancer patient blood is an established diagnostic assay used to evaluate patient status as a singleplex test. However, in the coming age of personalized medicine, multiplex analysis of patient CTCs, including proteomic and genomic techniques, will have to be integrated with CTC isolation platform technologies. Advancements in microfabrication have demonstrated that CTCs can be isolated and analyzed using microfluidic lab-on-a-chip devices. However, to date, most microfluidic devices are either still in the development phase, not applicable to all clinical tests, or are not commercially available. To overcome these discrepancies, we describe an all-in-one device for the isolation and multiplexing of clinically applicable CTC assays. Microfilters present an ideal lab-on-a-chip platform for analysis of CTCs as non-toxic and inert materials allow for a multitude of tests from cell growth through clinical staining techniques, all without background interference. Lithographically fabricated microfilters, can be made with high porosity, precise pore dimensions, arrayed pore distribution, and optimized for CTC size-based isolation. In this study we describe microfilter use in isolation and in situ analysis of CTCs using multiple sequential techniques including culture, FISH, histopathological analysis, H&E staining, photobleaching and re-staining. Further, as a proof of principle, we then describe the ability to quantitatively release patient derived CTCS from the microfilters for potential use in downstream genomic/proteomic analysis.

[No-touch pancreatectomy and radical antegrade modular pancreatosplenectomy: a systematic review]

AIM

To summarize the data of 'no-touch isolation technique' (NIT) for pancreatoduodenectomy and radical antegrade modular pancreato-splenectomy (RAMPS) for pancreatic malignancies.

MATERIAL AND METHODS

We looked through Pubmed and Cochrane databases for scientific papers published from January 2000 until September 2014.

RESULTS

Eight studies were included. There were 7 retrospective cohort studies and one randomized controlled trial (RCT). Mean operation time and blood loss were 267 min (198-386 min) and 132 ml (331-744 ml) respectively. Mean morbidity rate was 35% (17-58%). There was no 30-day mortality. Mean incidence of R0-resection varied from 50% to 97% with average value 84%. Median survival was reported in 3 studies (17, 18 and 26 months). Five-year actuarial overall survival was reported in 4 studies (31, 36, 40 and 53%).

CONCLUSION

Positive results of NIT and RAMPS might justify further evaluation of the method in pancreatic cancer. Prospective randomized controlled trials needs to be done to demonstrate the oncological value of this novel surgical technique.

Individual profiling of circulating tumor cell composition in patients with non-small cell lung cancer receiving platinum based treatment

BACKGROUND

Circulating tumor cells (CTC) could serve as a "liquid biopsy" for individualizing and monitoring treatment in patients with solid tumors as recently shown by our group. We assessed which non-hematopoietic cell types are identifiable in the peripheral blood of patients with non-small cell lung cancer (NSCLC) and correlated those to clinical characteristics.

METHODS

Blood from NSCLC patients (n=43) was processed as previously described. For subtype analyses CTC were negatively enriched by hematopoietic cell depletion. The remaining cell suspension included pre-enriched tumor cells and was spun onto glass slides and further characterized by multi-immunofluorescence staining against epithelial markers pan-cytokeratin (CK) and epithelial cell adhesion molecule (EpCAM), mesenchymal marker N-cadherin, stem cell marker CD133, hematopoietic marker CD45 and nuclear counterstain DAPI. Individual cell type profiles were analyzed and correlated to therapeutic outcome.

RESULTS

Among other associations of CTC subtypes with clinical parameters Kaplan-Meier test revealed that an increased CD133-positive to pan-CK-positive cell type ratio (stem cell like to epithelial ratio) and the presence of mesenchymal N-cadherin+ cells, both were significantly associated to shortened PFS (2 vs. 8 months, P=0.003, HR =4.43; 5 vs. 8 months, P=0.03, HR =2.63).

CONCLUSIONS

Our data suggest that different CTC populations are identifiable in peripheral blood and that these individual cell type profiles might be used to predict outcome to platinum based systemic therapies in lung cancer patients.

Detection of circulating tumor cell subpopulations in patients with head and neck squamous cell carcinoma (HNSCC)

Background

Since image based diagnostic tools fail to detect early metastasis in head and neck squamous cell carcinoma (HNSCC) it is crucial to develop minimal invasive diagnostic methods. A promising approach is to identify and characterize circulating tumor cells (CTC) in the peripheral blood of HNSCC patients. In this pilot study, we assessed which non-hematopoietic cell types are identifiable and whether their numbers differ in pre- and postoperative blood samples.

Methods

20 ml citrated peripheral blood was taken from 10 HNSCC patients before and after curative resection. CTC were enriched using density gradient centrifugation. CTC presence was verified by multi-immunofluorescence staining against cytokeratin (CK; epithelial), N-cadherin (mesenchymal); CD133 (stem-cell), CD45 (hematopoietic) and DAPI (nucleus). Individual cell type profiles were analyzed.

Results

We were able to detect cells with epithelial properties like CK+/N-cadherin−/CD45− and CK+/CD133−/CD45− as well as cells with mesenchymal features such as N-cadherin+/CK−/CD45− and cells with both characteristics like N-cadherin+/CK+/CD45−. We also observed cells showing stem cell-like features like CD133+/CK−/CD45− and cells with both epithelial and stem cell-like features such as CD133+/CK+/CD45−. The number of CK positive cells (p = 0.002), N-cadherin positive cells (p = 0.002) and CD133 positive cells (p = 0.01) decreased significantly after resection. Kaplan-Meier test showed that the survival was significantly shorter when N-cadherin+ cells were present after resection (p = 0.04; 474 vs. 235 days; [HR] = 3.1).

Conclusions

This is - to the best of our knowledge- the first pilot study identifying different CTC populations in peripheral blood of HNSCC patients and showing that these individual cell type profiles may have distinct clinical implications.

Gene expression profiling of circulating tumor cells in breast cancer

BACKGROUND

Determining the transcriptional profile of circulating tumor cells (CTCs) may allow the acquisition of clinically relevant information while overcoming tumor heterogeneity-related biases associated with use of tissue samples for biomarker assessment. However, such molecular characterization is challenging because CTCs are rare and outnumbered by blood cells.

METHODS

Here, we describe a technical protocol to measure the expression of >29 000 genes in CTCs captured from whole blood with magnetic beads linked with antibodies against epithelial cell adhesion molecule (EpCAM) and the carcinoma-associated mucin, MUC1, designed to be used for CTC characterization in clinical samples. Low numbers of cells (5-200) from the MCF7 and MDA-MB-468 breast cancer cell lines were spiked in healthy donor blood samples and isolated with the AdnaTest EMT-1/Stem CellSelect kit. Gene expression profiles (GEPs) were obtained with the WG-DASL HT assay and compared with GEPs obtained from RNA isolated from cultured cell lines and unspiked samples.

RESULTS

GEPs from samples containing 25 or more spiked cells correlated (r = 0.95) with cognate 100-ng RNA input samples, clustered separately from blood control samples, and allowed MCF7 and MDA-MB-468 cells to be distinguished. GEPs with comparable technical quality were also obtained in a preliminary series of clinical samples.

CONCLUSIONS

Our approach allows technically reliable GEPs to be obtained from isolated CTCs for the acquisition of biologically useful information. It is reproducible and suitable for application in prospective studies to assess the clinical utility of CTC GEPs, provided that >25 CTCs can be isolated.

Laboratory medicine and medical oncology: the tale of two Cinderellas

Cancer represents a leading cause of death in the developed countries. The past 50 years have witnessed major progress in both laboratory medicine and clinical oncology that has translated into improved prognosis of cancer patients. From the humble beginnings as unrelated specialties, major advances in the understanding of molecular bases of cancer progression led to increased interactions between laboratory medicine and clinical (mostly medical) oncology. Laboratory medicine is now an integral part of the management of cancer patients. The many aspects of the role of laboratory medicine in clinical oncology include the determination of biomarkers that are used in establishing the diagnosis, predicting response to therapy or prognosis, study of the host response to tumor growth, detection of treatment toxicity and determining the concentrations of anticancer drugs.

Rapid translation of circulating tumor cell biomarkers into clinical practice: technology development, clinical needs and regulatory requirements

The great hope in circulating tumor cell (CTC) research lies in the use of these rare cells as an accessible "fluid biopsy" that would permit frequent, minimally invasive sampling of tumor cells for similar molecular assays that are performed on traditional biopsies. Given the rarity of CTCs in peripheral circulation, microscale methods show great promise and superiority to capture and analyze these cells from patients with solid tumors. Novel technologies that produce validated CTC biomarkers may finally provide medical oncologists the tools needed to provide precise, personalized medical care for patients with advanced cancer. However, few CTC technologies demonstrate both experimental and clinical evidence of an accurate, reliable and reproducible assay that also meets the regulatory requirements to enter routine clinical practice. Many opportunities exist to incorporate clinical needs and regulatory benchmarks into technology development to more quickly garner FDA approval to direct decisions on patient care. This review will address: 1) device development tailored to address predictive, prognostic and/or therapeutic needs across the multitude of malignancies and disease stages; 2) validation benchmarks for clinical assay development; 3) early establishment of standard operating procedures for sample acquisition and analysis; 4) demonstration of clinical utility; 5) clinical qualification of a novel biomarker; and 6) integration of a newly validated and qualified technology into routine clinical practice. Early understanding and incorporation of these regulatory requirements into assay development can simplify and speed the integration of these novel technologies into patient care. Meeting these benchmarks will lead to the true personalization of cancer therapies, directing initial and subsequent treatments for each individual based on initial tumor characteristics while monitoring for emerging mechanisms of resistance in these continually evolving tumors.

The systematic study of circulating tumor cell isolation using lithographic microfilters

Circulating tumor cells (CTCs) disseminated into peripheral blood from a primary, or metastatic, tumor can be used for early detection, diagnosis and monitoring of solid malignancies. CTC isolation by size exclusion techniques have long interested researchers as a simple broad based approach, which is methodologically diverse for use in both genomic and protein detection platforms. Though a variety of these microfiltration systems are employed academically and commercially, the limited ability to easily alter microfilter designs has hindered the optimization for CTC capture. To overcome this problem, we studied a unique photo-definable material with a scalable and mass producible photolithographic fabrication method. We use this fabrication method to systematically study and optimize the parameters necessary for CTC isolation using a microfiltration approach, followed by a comparison to a "standard" filtration membrane. We demonstrate that properly designed microfilters can capture MCF-7 cancer cells at rate of 98 ± 2% if they consist of uniform patterned distributions, ≥160 000 pores, and 7 μm pore diameters.

In vitro validation of an ultra-sensitive scanning fluorescence microscope for analysis of circulating tumor cells

Analysis of circulating tumor cells (CTC) holds promise of providing liquid biopsies from patients with cancer. However, current methods include enrichment procedures. We present a method (CytoTrack®), where CTC from 7.5 mL of blood is stained, analyzed and counted by a scanning fluorescence microscope. The method was validated by breast cancer cells (MCF-7) spiked in blood from healthy donors. The number of cells spiked in each blood sample was exactly determined by cell sorter and performed in three series of three samples spiked with 10, 33 or 100 cells in addition with three control samples for each series. The recovery rate of 10, 33 and 100 tumor cells in a blood sample was 55%, 70% and 78%, percent coefficient of variation (CV%) for samples was 59%, 32% and 18%, respectively. None of the control samples contained CTC. In conclusion, the method has been validated to highly sensitively detect breast cancer cells in spiking experiments and should be tested on blood samples from breast cancer patients. The method could benefit from automation that could reduce the CV%, and further optimization of the procedure to increase the recovery.

Molecular characterization of circulating tumor cells in breast cancer: challenges and promises for individualized cancer treatment

Blood testing using Circulating Tumor Cells (CTCs) has emerged as one of the hottest fields in cancer diagnosis. Research on CTCs present nowadays a challenge, as these cells are well defined targets for understanding tumour biology and improving cancer treatment. The presence of tumor cells in patient's bone marrow or peripheral blood is an early indicator of metastasis and may signal tumor spread sooner than clinical symptoms appear and imaging results confirm a poor prognosis. CTC enumeration can serve as a "liquid biopsy" and an early marker to assess response to systemic therapy. Definition of biomarkers based on comprehensive characterization of CTCs has a strong potential to be translated to individualized targeted treatments and spare breast cancer patients unnecessary and ineffective therapies but also to reduce the costs for the health system and to downsize the extent and length of clinical studies. In this review, we briefly summarize recent studies on the molecular characterization of circulating tumor cells in breast cancer and discuss challenges and promises of CTCs for individualized cancer treatment.

Circulating tumor cells as therapy-related biomarkers in cancer patients

Carcinomas (tumors of epithelial origin) are responsible for most of all new cancers in the industrialized countries. Due to the high mortality rate caused by the metastatic spread of aggressive cancer cells, there is an urgent demand in finding new biomarkers, which should detect early formation of metastases and monitor efficacy of systemic adjuvant therapy in a timely manner. It has been considered that the molecular analysis of cells which are shed from tumors into the blood system (circulating tumor cells (CTCs)) might provide new insights for the clinical management of cancer, probably far earlier than using traditional high-resolution imaging technologies. Clinical trials indicated that CTCs can be deployed for diagnostic, monitoring, and prognostic purposes. Furthermore, these cells are discussed to be suitable as predictive markers. In any case, identification of CTCs requires innovative and challenging technologies as detection methods should be specific, sensitive, standardized, and highly reproducible. Although many different approaches have been developed until now, only the CellSearch™ method has been cleared by the American Food and Drug Administration. Although the detection of CTCs has already shown to have a prognostic impact in many tumor entities including breast, prostate, lung and colon cancer, ongoing and future studies are aimed to explore whether CTCs can be used for an individual therapy decision making including novel immunotherapeutic approaches. This review discusses (1) different detection strategies for CTCs, (2) their clinical impact, and (3) the potential use of CTCs guiding the treatment of individual cancer patients.

Comparison of three molecular assays for the detection and molecular characterization of circulating tumor cells in breast cancer

Introduction

Comparison studies between different analytical methodologies for circulating tumor cells (CTC) detection and molecular characterization are urgently needed, since standardization of assays is essential before their use in clinical practice.

Methods

We compared three different CTC molecular assays. To avoid discrepancies due to pre-analytical errors we used the same cDNAs throughout our study. CTC were isolated using anti-EpCAM and anti-MUC1 coated magnetic beads from 2 × 5 ml of peripheral blood of 254 early and 51 metastatic breast cancer patients and 30 healthy individuals. The same cDNAs were analyzed by: a) singleplex RT-qPCR assay for CK-19; b) multiplex RT-qPCR for CK-19, HER-2, MAGE- A3, and PBGD; and c) a commercially available molecular assay (AdnaTest BreastCancer) for GA733-2, MUC-1, HER-2 and beta-actin.

Results

In early breast cancer, CK-19 RT-qPCR, multiplex RT-qPCR and the AdnaTest, were positive for the presence of CTC in 14.2%, 22.8% and 16.5% subjects, respectively. The concordance between the AdnaTest and CK-19 RT-qPCR was 72.4% while between the AdnaTest and multiplex RT-qPCR was 64.6%. In patients with overt metastasis, CK-19 RT-qPCR, multiplex RT-qPCR and the AdnaTest were positive in 41.2%, 39.2% and 54.9% patients, respectively. The concordance between the AdnaTest and CK-19 RT-qPCR was 70.6% while between the AdnaTest and multiplex RT-qPCR was 68.6%.

Conclusions

All CTC assays gave similar results in about 70% of cases. Better agreement was found in the metastatic setting, possibly explained by the higher tumor load in this group. Discordances could be attributed to the different gene transcripts used to evaluate CTC positivity. Our results indicate the importance of CTC heterogeneity for their detection by different analytical methodologies.

Insulin-like growth factor receptor I (IGF-IR) and vascular endothelial growth factor receptor 2 (VEGFR-2) are expressed on the circulating epithelial tumor cells of breast cancer patients

BACKGROUND

Circulating epithelial tumor cell (CETC) analysis is a promising diagnostic field for estimating the risk for metastatic relapse and progression in patients with malignant disease. CETCs characterization can be used as a liquid biopsy for prognostic and predictive purposes in breast and other cancers. IGF-IR and VEGFR-2 play an important role in tumor growth and the progression of cancer disease. The purpose of the current study was therefore to investigate their expression on CETCs.

METHODS

CETCs were determined from the blood of 50 patients suffering from breast cancer. The number of vital CETCs and the expression of IGF-IR and VEGFR-2 were investigated using the maintrac® method.

RESULTS

IGF-IR and VEGFR-2 expression on the surface of CETCs were detected in 84% of patients. A statistically high correlation was found between IGF-IR and VEGFR-2 (r = 0.745 and p<0.001) on the CETCs. The co-expression of both receptors was confirmed in some experiments and ranged between 70% and 100%. Statistically significant correlations were observed between the number of CETCs and IGF-IR (r = 0.315 and p<0.05) and VEGFR-2 (r = 0.310 and p<0.05) expression. The presence of CETCs and the level of IGF-IR and VEGFR-2 expression were not associated with tumor stage, hormone receptor status or nodal/distant metastasis.

SUMMARY

In this study, a parallel and co-expression of IGF-IR and VEGFR-2 was examined on the surface of CETCs in breast cancer patients for the first time. Characterization of CETCs may be a promising approach for the rational design of targeted anticancer therapies.

SOX17 Promoter Methylation in Circulating Tumor Cells and Matched Cell-Free DNA Isolated from Plasma of Patients with Breast Cancer

INTRODUCTION

Detection of circulating tumor cells (CTCs) and cell-free DNA (cfDNA) in the peripheral blood of patients with solid tumors has been widely studied for the early detection of metastatic spread. We evaluated whether there was an association between the origin of cfDNA and CTCs. We investigated whether SRY (sex determining region Y)-box 17 (SOX17) promoter methylation in CTCs was associated with the methylation pattern of this gene in matched cfDNA isolated from plasma of patients with breast cancer.

METHODS

We examined SOX17 methylation in 79 primary breast tumors, in 114 paired samples of DNA isolated from CTCs and cfDNA, and in 60 healthy individuals. Isolated DNA was modified by sodium bisulfite and subjected to methylation specific PCR.

RESULTS

The SOX17 promoter was methylated in 68 (86.0%) of 79 of primary breast tumors. In CTCs, SOX17 was methylated in 19 (34.5%) of 55 patients with early breast cancer, 27 (45.8%) of 59 patients with metastatic cancer, and 1 (4.3%) of 23 healthy individuals, whereas in matched cfDNA SOX17 was methylated in 19 (34.5%) of 55, 24 (40.7%) of 59, and 1 (2.0%) of 49 of these same groups, respectively. There was a significant correlation between SOX17 methylation in cfDNA and CTCs in patients with early breast cancer (P = 0.008), but not in patients with verified metastasis (P = 0.283).

CONCLUSIONS

The SOX17 promoter is highly methylated in primary breast tumors, in CTCs isolated from patients with breast cancer, and in corresponding cfDNA samples. Our findings indicate a direct connection between the presence of CTCs and cfDNA in patients with operable breast cancer, after surgical removal of the primary tumor.

mRNA-Seq of single prostate cancer circulating tumor cells reveals recapitulation of gene expression and pathways found in prostate cancer

Circulating tumor cells (CTC) mediate metastatic spread of many solid tumors and enumeration of CTCs is currently used as a prognostic indicator of survival in metastatic prostate cancer patients. Some evidence suggests that it is possible to derive additional information about tumors from expression analysis of CTCs, but the technical difficulty of isolating and analyzing individual CTCs has limited progress in this area. To assess the ability of a new generation of MagSweeper to isolate intact CTCs for downstream analysis, we performed mRNA-Seq on single CTCs isolated from the blood of patients with metastatic prostate cancer and on single prostate cancer cell line LNCaP cells spiked into the blood of healthy donors. We found that the MagSweeper effectively isolated CTCs with a capture efficiency that matched the CellSearch platform. However, unlike CellSearch, the MagSweeper facilitates isolation of individual live CTCs without contaminating leukocytes. Importantly, mRNA-Seq analysis showed that the MagSweeper isolation process did not have a discernible impact on the transcriptional profile of single LNCaPs isolated from spiked human blood, suggesting that any perturbations caused by the MagSweeper process on the transcriptional signature of isolated cells are modest. Although the RNA from patient CTCs showed signs of significant degradation, consistent with reports of short half-lives and apoptosis amongst CTCs, transcriptional signatures of prostate tissue and of cancer were readily detectable with single CTC mRNA-Seq. These results demonstrate that the MagSweeper provides access to intact CTCs and that these CTCs can potentially supply clinically relevant information.

Prognostic value of circulating tumor cells in primary and metastatic breast cancer

In patients with breast cancer, there is evidence correlating the presence of circulating tumor cells (CTCs) with disease-free survival, progression-free survival and overall survival. The detection of CTCs may be useful in gaining a better understanding of the mechanisms of tumor growth and in the improvement of patient management. This review analyzes the prognostic and predictive relevance of CTCs through the principal published studies, cytometric techniques and nucleic acid-based approaches to detect CTCs, phenotypic expression of specific receptors, molecular pathways and genetic signatures for potential tailored therapies.

Adhesion receptors as therapeutic targets for circulating tumor cells

Metastasis contributes to >90% of cancer-associated mortality. Though primary tumors can be removed by surgical resection or chemo/radiotherapy, metastatic disease is a great challenge to treatment due to its systemic nature. As metastatic “seeds,” circulating tumor cells (CTCs) are believed to be responsible for dissemination from a primary tumor to anatomically distant organs. Despite the possibility of physical trapping of CTCs in microvessels, recent advances have provided insights into the involvement of a variety of adhesion molecules on CTCs. Such adhesion molecules facilitate direct interaction with the endothelium in specific tissues or indirectly through leukocytes. Importantly, significant progress has been made in understanding how these receptors confer enhanced invasion and survival advantage during hematogenous circulation of CTCs through recruitment of macrophages, neutrophils, platelets, and other cells. This review highlights the identification of novel adhesion molecules and how blocking their function can compromise successful seeding and colonization of CTCs in new microenvironment. Encouraged by existing diagnostic tools to identify and isolate CTCs, strategic targeting of these adhesion molecules to deliver conventional chemotherapeutics or novel apoptotic signals is discussed for the neutralization of CTCs in the circulation.

Circulating tumor cells in melanoma patients

Circulating tumor cells (CTCs) are of recognized importance for diagnosis and prognosis of cancer patients. With melanoma, most studies do not show any clear relationship between CTC levels and stage of disease. Here, CTCs were enriched (∼400X) from blood of melanoma patients using a simple centrifugation device (OncoQuick), and 4 melanocyte target RNAs (TYR, MLANA, MITF, and MIF) were quantified using QPCR. Approximately one-third of melanoma patients had elevated MIF and MLANA transcripts (p<0.0001 and p<0.001, respectively) compared with healthy controls. In contrast, healthy controls had uniformly higher levels of TYR and MITF than melanoma patients (p<0.0001). There was a marked shift of leukocytes into the CTC-enriched fractions (a 430% increase in RNA recovery, p<0.001), and no relationship between CTC levels and stage of disease was found. CTCs were captured on microfabricated filters and cultured. Captured melanoma CTCs were large cells, and consisted of 2 subpopulations, based on immunoreactivity. One subpopulation (∼50%) stained for both pan-cytokeratin (KRT) markers and the common leukocyte marker CD-45, whereas the second subpopulation stained for only KRT. Since similar cells are described in many cancers, we also examined blood from colorectal and pancreatic cancer patients. We observed analogous results, with most captured CTCs staining for both CD-45/KRT markers (and for the monocyte differentiation marker CD-14). Our results suggest that immature melanocyte-related cells (expressing TYR and MITF RNA) may circulate in healthy controls, although they are not readily detectable without considerable enrichment. Further, as early-stage melanomas develop, immature melanocyte migration into the blood is somehow curtailed, whereas a significant proportion of patients develop elevated CTC levels (based on MIF and MLANA RNAs). The nature of the captured CTCs is consistent with literature describing leukocyte/macrophage-tumor cell fusion hybrids, and their role in metastatic progression.

A simple multicolor flow cytometry protocol for detection and molecular characterization of circulating tumor cells in epithelial cancers

Circulating tumor cells (CTCs) might not only serve as prognostic marker but could also be useful for monitoring treatment efficacy. A multicolor flow cytometry protocol for their detection and molecular characterization in peripheral blood was developed which consisted of erythrocyte lysis followed by staining of cells with fluorochrome-labeled antibodies against CD45 and the epithelial markers EpCam and cytokeratin 7/8. For reducing the number of events acquired by flow cytometry, an electronic threshold for the fluorescent signals from the epithelial markers was applied. After establishment of the protocol by using spiking experiments, its suitability to determine the absolute number of CTCs as well as their expression of epidermal growth factor receptor (EGFR) and its phosphorylated form (phospho-EGFR) in blood samples from patients with squamous cell carcinoma of the head and neck (SCCHN) was validated. Spiking experiments demonstrated an excellent recovery (mean 85%) and a linear performance (R(2) = 0.98) of the protocol. Sensitivity and specificity were comparable to our former protocol using immunomagnetic CTC pre-enrichment. The analysis of 33 SCCHN patient samples revealed the presence of CTCs in 33.3% of cases with a mean ± SD of 1.5 ± 0.5 CTCs per 3.75 ml blood. EGFR was expressed in 100% and phospho-EGFR in 36.4% of the CTC+ cases. We have established a simple and sensitive multicolor flow cytometry protocol for detection of CTCs in patients with epithelial cancers including SCCHN which will allow their detailed molecular characterization.

Molecular assays for the detection and characterization of CTCs

Molecular characterization for circulating tumor cells (CTCs) can be used to better understand the biology of metastasis, to improve patient management and help to identify novel targets for biological therapies aimed to prevent metastatic relapse. New areas of research are directed towards developing novel sensitive assays for CTC molecular characterization. Towards this direction, molecular detection technologies that take advantage of the extreme sensitivity and specificity of PCR, offer many advantages, such as high sensitivity, specificity, and significant flexibility in the clinical lab setting, in terms of high-throughput analysis, multiplexing, and quality control issues. Using molecular assays, a variety of molecular markers such as multiple gene expression, DNA methylation markers, DNA mutations, and miRNAs have been detected and quantified in CTCs in various cancer types, enabling their molecular characterization. Here, we present the main molecular detection technologies currently used for CTC analysis and molecular characterization.

Lack of evidence for increased level of circulating urothelial cells in the peripheral blood after transurethral resection of bladder tumors

PURPOSE

Aggressive intervention against the bladder wall during transurethral resection of bladder tumors (TURBT) causes damage and leakage from blood vessels to the bladder lumen. The aim of this study was to determine whether TURBT could increase the level of circulating urothelial cells.

METHODS

Expression of tumor markers, discriminative for nucleated blood cells and urothelium, was evaluated by quantitative (q) RT-PCR on RNA isolated from peripheral blood samples of 51 patients who underwent TURBT for ≥cT1c bladder tumors.

RESULTS

Four of 14 studied genes, epidermal growth factor receptor (EGFR), Collagen α-1(I) chain, Mast/stem cell growth factor receptor (KIT) and CD47, exhibited significant differences in gene expression between controls and cancer patients. While TURBT did not significantly increase the number of PCR-positive results of any transcripts, positive RT-PCR detection for EGFR was significantly less frequent on day 30 compared to results obtained before surgery.

CONCLUSIONS

Although the results of our study do not provide evidence for increased tumor cell release into the peripheral blood after TURBT, they seem to indicate that EGFR mRNA measurement in the blood may provide useful information for urologists.