Circulating Tumor Cell Composition in Renal Cell Carcinoma

CXCL12-loaded-hydrogel (CLG): A new device for metastatic circulating tumor cells (CTCs) capturing and characterization

Background

Circulating Tumor Cells (CTCs) represent a small, heterogeneous population that comprise the minority of cells able to develop metastasis. To trap and characterize CTCs with metastatic attitude, a CXCL12-loaded hyaluronic-gel (CLG) was developed. CXCR4+cells with invasive capability would infiltrate CLG.

Methods

Human colon, renal, lung and ovarian cancer cells (HT29, A498, H460 and OVCAR8 respectively) were seeded on 150 μl Empty Gels (EG) or 300 ng/ml CXCL12 loaded gel (CLG) and allowed to infiltrate for 16 h. Gels were then digested and fixed with 2 % FA-HAse for human cancer cell enumeration or digested with HAse and cancer cells recovered. CLG-recovered cells migrated toward CXCL12 and were tested for colonies/spheres formation. Moreover, CXCR4, E-Cadherin and Vimentin expression was assessed through flow cytometry and RT-PCR. The clinical trial "TRAP4MET" recruited 48 metastatic/advanced cancer patients (8 OC, 8 LC, 8 GBM, 8 EC, 8 RCC and 8 EC). 10 cc whole blood were devoted to PBMCs extraction (7 cc) and ScreenCell™ filters (3 cc) CTCs evaluation. Ficoll-isolated patient's PBMCs were seeded over CLG and allowed to infiltrate for 16 h; gels were digested and fixed with 2 % FA-HAse, cells stained and DAPI+/CD45-/pan-CK + cells enumerated as CTCs.

Results

Human cancer cells infiltrate CLG more efficiently than EG (CLG/EG ratio 1.25 for HT29/1.58 for A498/1.71 for H460 and 2.83 for OVCAR8). CLG-recovered HT29 cells display hybrid-mesenchymal features [low E-cadherin (40 %) and high vimentin (235 %) as compared to HT29], CXCR4 two-fold higher than HT29, efficiently migrate toward CXCL12 (two-fold higher than HT29) and developed higher number of colonies (171 ± 21 for HT29-CLG vs 131 ± 8 colonies for HT29)/larger spheres (spheroid area: 26561 ± 6142 μm2 for HT29-CLG vs 20297 ± 7238 for HT29). In TRAP4MET clinical trial, CLG-CTCs were isolated in 8/8 patients with OC, 6/8 with LC, 6/8 with CRC, 8/8 with EC, 8/8 with RCC cancer and 5/8 with GBM. Interestingly, in OC, LC and GBM, CLG isolated higher number of CTCs as compared to the conventional ScreenCell™ (CLG/SC ratio = 1.88 for OC, 2.47 for LC and 11.89 for GBM). Bland and Altman blot analysis and Passing and Bablok regression analysis showed concordance between the methodological approaches but indicate that SC and CLG are not superimposable suggesting that the two systems select cells with different features.

Conclusion

CLG might represent a new and easy tool to isolate invasive CTCs in multiple cancers such as OC, LC and GBM at today orphan of reliable methods to consistently detect CTCs.

Diagnostic liquid biopsy biomarkers in renal cell cancer

The clinical presentation of renal cell cancer (RCC) is shifting towards incidental and early detection, creating new challenges in RCC diagnosis. Overtreatment might be reduced with the development of new diagnostic biomarkers to distinguish benign from malignant small renal masses (SRMs). Differently from tissue biopsies, liquid biopsies are obtained from a patient's blood or urine and, therefore, are minimally invasive and suitable for longitudinal monitoring. The most promising types of liquid biopsy biomarkers for RCC diagnosis are circulating tumour cells, extracellular vesicles (EVs) and cell-free DNA. Circulating tumour cell assays have the highest specificity, with low processing time and costs. However, the biological characteristics and low sensitivity limit the use of these markers in SRM diagnostics. Cell-free DNA might complement the diagnosis of high-volume RCC, but the potential for clinical application in SRMs is limited. EVs have the highest biological abundance and the highest sensitivity in identifying low-volume disease; moreover, the molecular characteristics of these markers make EVs suitable for multiple analytical applications. Thus, currently, EV assays have the greatest potential for diagnostic application in RCC (including identification of SRMs). All these liquid biomarkers have potential in clinical practice, pending validation studies. Biomarker implementation will be needed to also improve characterization of RCC subtypes. Last, diagnostic biomarkers might be extended to prognostic or predictive applications.

Management of Renal Cell Carcinoma: Promising Biomarkers and the Challenges to Reach the Clinic

The incidence of renal cell carcinoma (RCC) is increasing worldwide, yet research within this field is lagging behind other cancers. Despite increased detection of early disease as a consequence of the widespread use of diagnostic CT scans, 25% of patients have disseminated disease at diagnosis. Similarly, around 25% progress to metastatic disease following curatively intended surgery. Surgery is the cornerstone in the treatment of RCC; however, when the disease is disseminated, immunotherapy or immunotherapy in combination with a tyrosine kinase inhibitor is the patient's best option. Immunotherapy is a potent treatment, with durable treatment responses and potential to cure the patient, but only half of the patients benefit from the administered treatment, and there are currently no methods that can identify which patients will respond to immunotherapy. Moreover, there is a need to identify the patients in greatest risk of relapsing after surgery for localized disease and direct adjuvant treatment there. Even though several molecular biomarkers have been published to date, we are still lacking routinely used biomarkers to guide optimal clinical management. The purpose of this review is to highlight some of the most promising biomarkers, discuss the efforts made within this field to date, and describe the barriers needed to be overcome to have reliable and robust predictive and prognostic biomarkers in the clinic for renal cancer.

Circulating tumor cells as a predictor and prognostic tool for metastatic clear cell renal carcinoma: An immunocytochemistry and genomic analysis

BACKGROUND

Treatment of metastatic clear cell renal carcinoma (mccRCC) has changed dramatically over the past 20 years, without improvement in the development of biomarkers. Recently, circulating tumor cells (CTCs) have been validated as a prognostic and predictive tool for many solid tumors.

OBJECTIVE

We evaluated CTCs in blood samples obtained from patients diagnosed with mccRCC. Comparisons of CTC counts, protein expression profiling, and DNA mutants were made in relation to overall survival and progression-free survival.

METHODS

CTCs were isolated from 10 mL blood samples using the ISET® system (Isolation by SizE of Tumor Cells; Rarecells, France) and counted. Protein expression was evaluated in immunocytochemistry assays. DNA mutations were identified with next generation sequencing (NGS).

RESULTS

Blood samples (10 mL) were collected from 12 patients with mccRCC before the start of first-line systemic therapy, and again 30 and 60 days after the start of treatment. All 12 patients had CTCs detected at baseline (median, 1.5 CTCs/mL; range: 0.25-7.75). Patients with CTC counts greater than the median had two or more metastatic sites and exhibited worse progression-free survival (19.7 months) compared to those with CTC counts less than the median (31.1 months). Disease progression was observed in 7/12 patients during the study. Five of these patients had baseline CTC counts greater than the median, one had higher CTC levels at the second blood collection, and one patient had CTCs present at 1 CTC/mL which positively stained for PD-L1, N-cadherin, VEGF, and SETD2. CTC DNA from six patients with worse outcomes was subjected to NGS. However, no conclusions could be made due to the low variant allele frequencies.

CONCLUSION

Detection of CTCs in patients with mccRCC receiving first-line treatment is a feasible tool with prognostic potential since increased numbers of CTCs were found to be associated with metastasis and disease progression.

Circulating tumor cells in colorectal cancer - a review of detection methods and clinical relevance

Colorectal cancer (CRC) is the third most common cancer; it is one of the leading malignancies contributing to cancer mortality. Colorectal cancer is the third most diagnosed cancer in men and the second in women worldwide. Diagnosis of CRC depends on several clinical features such as age, primary site, tumor-node-metastasis stage, genetic parameters and the presence or absence of metastasis. The latter is a phenomenon that is induced by the shedding of tumor cells in the blood circulation by the primary tumor. Such cells are known as circulating tumor cells (CTCs). The detection of CTCs is quite challenging due to their scarceness; thus it requires their enrichment and characterization. Studying the utility of CTCs in the diagnosis of CRC has been the aim of several studies; they demonstrated that ≥ 3 CTCs in 7.5 ml of blood is correlated with a worse prognosis and short progression-free and overall survival. Circulating tumor cells have also been monitored to study treatment response and predict future relapses. The present review aims to bring to light the different techniques used to detect and characterize these malignant cells in the peripheral blood of cancer patients as well as the clinical relevance of CTCs in CRC patients.

Clinical Validation of a Size-Based Microfluidic Device for Circulating Tumor Cell Isolation and Analysis in Renal Cell Carcinoma

Renal cell carcinoma (RCC) presents as metastatic disease in one third of cases. Research on circulating tumor cells (CTCs) and liquid biopsies is improving the understanding of RCC biology and metastases formation. However, a standardized, sensitive, specific, and cost-effective CTC detection technique is lacking. The use of platforms solely relying on epithelial markers is inappropriate in RCC due to the frequent epithelial-mesenchymal transition that CTCs undergo. This study aimed to test and clinically validate RUBYchip™, a microfluidic label-free CTC detection platform, in RCC patients. The average CTC capture efficiency of the device was 74.9% in spiking experiments using three different RCC cell lines. Clinical validation was performed in a cohort of 18 patients, eight non-metastatic (M0), five metastatic treatment-naïve (M1TN), and five metastatic progressing-under-treatment (M1TP). An average CTC detection rate of 77.8% was found and the average (range) total CTC count was 6.4 (0-27), 101.8 (0-255), and 3.2 (0-10), and the average mesenchymal CTC count (both single and clustered cells) was zero, 97.6 (0-255), and 0.2 (0-1) for M0, M1TN, and M1TP, respectively. CTC clusters were detected in 25% and 60% of M0 and M1TN patients, respectively. These results show that RUBYchip™ is an effective CTC detection platform in RCC.

Circulating Tumor Cells as Biomarkers for Renal Cell Carcinoma: Ready for Prime Time?

Renal cell carcinoma (RCC) is among the 15 most common cancers worldwide, with rising incidence. In most cases, this is a silent disease until it reaches advance stages, demanding new effective biomarkers in all domains, from detection to post-therapy monitoring. Circulating tumor cells (CTC) have the potential to provide minimally invasive information to guide assessment of the disease's aggressiveness and therapeutic strategy, representing a special pool of neoplastic cells which bear metastatic potential. In some tumor models, CTCs' enumeration has been associated with prognosis, but there is a largely unexplored potential for clinical applicability encompassing screening, diagnosis, early detection of metastases, prognosis, response to therapy and monitoring. Nonetheless, lack of standardization and high cost hinder the translation into clinical practice. Thus, new methods for collection and analysis (genomic, proteomic, transcriptomic, epigenomic and metabolomic) are needed to ascertain the role of CTC as a RCC biomarker. Herein, we provide a critical overview of the most recently published data on the role and clinical potential of CTCs in RCC, addressing their biology and the molecular characterization of this remarkable set of tumor cells. Furthermore, we highlight the existing and emerging techniques for CTC enrichment and detection, exploring clinical applications in RCC. Notwithstanding the notable progress in recent years, the use of CTCs in a routine clinical scenario of RCC patients requires further research and technological development, enabling multimodal analysis to take advantage of the wealth of information they provide.

The Role of Circulating Biomarkers in the Oncological Management of Metastatic Renal Cell Carcinoma: Where Do We Stand Now?

Renal cell carcinoma (RCC) is an increasingly common malignancy that can progress to metastatic renal cell carcinoma (mRCC) in approximately one-third of RCC patients. The 5-year survival rate for mRCC is abysmally low, and, at the present time, there are sparingly few if any effective treatments. Current surgical and pharmacological treatments can have a long-lasting impact on renal function, as well. Thus, there is a compelling unmet need to discover novel biomarkers and surveillance methods to improve patient outcomes with more targeted therapies earlier in the course of the disease. Circulating biomarkers, such as circulating tumor DNA, noncoding RNA, proteins, extracellular vesicles, or cancer cells themselves potentially represent a minimally invasive tool to fill this gap and accelerate both diagnosis and treatment. Here, we discuss the clinical relevance of different circulating biomarkers in metastatic renal cell carcinoma by clarifying their potential role as novel biomarkers of response or resistance to treatments but also by guiding clinicians in novel therapeutic approaches.

Perioperative Circulating Tumor Cells (CTCs), MCTCs, and CTC-White Blood Cells Detected by a Size-Based Platform Predict Prognosis in Renal Cell Carcinoma

To explore the clinical significance of the perioperative counts of circulating tumor cells (CTCs), mesenchymal CTCs (MCTCs), and CTC- white blood cells (WBCs) in renal cell carcinoma patients. A total of 131 patients with renal cancer who underwent operation excision from our hospital were enrolled. In addition, 20 patients with benign renal diseases were recruited as a control. Blood samples were collected from the 131 patients, before operation and 3 months after surgery. Samples were also obtained simultaneously from the control group. CanPatrol CTC detection technique was used to enrich and identify CTCs, MCTCs, and CTC-WBCs. All enrolled patients were T1-3N0M0. From these, 52 patients with renal cancer underwent radical resection, while other 79 patients underwent nephron-sparing surgery. The positive rate of CTC, MCTC, and CTC-WBC before surgery were 95.4% (125/131), 61.1% (80/131), and 11.5% (15/131), respectively. Preoperative total CTCs, MCTCs, or CTC-WBCs were poorly correlated with patients' parameters. Preoperative CTC, MCTC, or CTC-WBC showed no association with progression-free survival (PFS). In contrast, postoperative total CTCs (≥6), positive MCTCs, and positive CTC-WBCs significantly correlated with recurrence and metastasis. These results remained independent indicators for worse PFS. In addition, the increased CTC and MCTC count after surgery also correlated with unfavorable PFS. The detection of six or more total CTCs, MCTC, or CTC-WBCs in peripheral blood after surgery might help to identify a subset of patients that have higher recurrent risk than the overall population of patients with at different stages of renal cancer.

Metastasis Prevention: Focus on Metastatic Circulating Tumor Cells

Metastasis is the main cause of cancer death. Metastatic foci are derived from tumor cells that detach from the primary tumor and then enter the circulation. Circulating tumor cells (CTCs) are generally associated with a high probability of distant metastasis and a negative prognosis. Most CTCs die in the bloodstream, and only a few cells form metastases. Such metastatic CTCs have a stem-like and hybrid epithelial-mesenchymal phenotype, can avoid immune surveillance, and show increased therapy resistance. Targeting metastatic CTCs and their progenitors in primary tumors and their descendants, particularly disseminated tumor cells, represents an attractive strategy for metastasis prevention. However, current therapeutic strategies mainly target the primary tumor and only indirectly affect metastasis-initiating cells. Here, we consider potential methods for preventing metastasis based on targeting molecular and cellular features of metastatic CTCs, including CTC clusters. Also, we emphasize current knowledge gaps in CTC biology that should be addressed to develop highly effective therapeutics and strategies for metastasis suppression.

Circulating tumor cell detection methods in renal cell carcinoma: A systematic review

Circulating tumor cells (CTCs) have a potential role as the missing renal cell carcinoma (RCC) biomarker. However, the available evidence is limited, and detection methods lack standardization, hindering clinical use. We performed a systematic review on CTC enrichment and detection methods, and its role as a biomarker in RCC. Full-text screening identified 54 studies. Reviewed studies showed wide heterogeneity, low evidence level, and high risk of bias. Various CTC detection platforms and molecular markers have been used, but none has proven to be superior. CTC detection and CTC count seem to correlate with staging and survival outcomes, although evidence is inconsistent. CTC research is still in an exploratory phase, particularly in RCC. Further studies are still necessary to achieve a standardization of techniques, molecular markers, CTC definitions, and terminology. This is essential to ascertain the role of CTCs as a biomarker and guide future liquid biopsy research in RCC.

Tumor heterogeneity and the potential role of liquid biopsy in bladder cancer

Bladder cancer (BC) is a heterogeneous disease that characterized by genomic instability and a high mutation rate. Heterogeneity in tumor may partially explain the diversity of responses to targeted therapies and the various clinical outcomes. A combination of cytology and cystoscopy is the standard methodology for BC diagnosis, prognosis, and disease surveillance. However, genomics analyses of single tumor‐biopsy specimens may underestimate the mutational burden of heterogeneous tumors. Liquid biopsy, as a promising technology, enables analysis of tumor components in the bodily fluids, such as blood and urine, at multiple time points and provides a minimally invasive approach that can track the evolutionary dynamics and monitor tumor heterogeneity. In this review, we describe the multiple faces of BC heterogeneity at the genomic and transcriptional levels and how they affect clinical care and outcomes. We also summarize the outcomes of liquid biopsy in BC, which plays a potential role in revealing tumor heterogeneity. Finally, we discuss the challenges that must be addressed before liquid biopsy can be widely used in clinical treatment.

Role of circulating tumor cells in patients with metastatic clear-cell renal cell carcinoma

PURPOSE

Circulating tumor cells (CTC) have been demonstrated to have prognostic and predictive role in certain human cancers. However, studies exploring their role in metastatic renal cell carcinoma (mRCC) are scarce. We aimed to evaluate the prognostic and predictive role of CTC in mRCC.

MATERIALS AND METHODS

In this prospective study, 35 patients with mRCC were analyzed for the presence of CTC before starting tyrosine kinase inhibitors (TKI). Progression-free and overall survival rates were estimated using the Kaplan-Meier curves and log-rank test. The prediction to TKI therapy was calculated with the response to treatment determined by standard imaging techniques.

RESULTS

Outcomes were assessed according to the CTC positivity at baseline, before the patients started TKI for mRCC. At a mean follow-up of 12.4 ± 4.1 months, disease progression was noted in 17 patients (48.6%) including 8 deaths (22.9%). CTC positive patients had a significantly lower progression-free survival rate (12.5% vs. 64.1%, respectively; P = 0.009) but not in the overall survival rate (75% vs. 76.3%, respectively; P = 0.88) in the Kaplan-Meier estimation curves. CTC positivity at baseline significantly predicted a poorer response to TKI (87.5% vs. 37.1%, P = 0.01). The multivariate Cox proportional hazards analysis showed that CTC at baseline was the most significant predictor of progression-free survival (hazard ratio 4.17, 95% confidence interval 1.41-11.99, P = 0.01).

CONCLUSIONS

Baseline CTC detection can be an important prognostic factor of progression-free survival and significant predictor of poor response to TKI in patients with metastatic RCC.

Surface engineering for efficient capture of circulating tumor cells in renal cell carcinoma: From nanoscale analysis to clinical application

Sensitive detection of circulating tumor cells (CTCs) from patients' peripheral blood facilitates on-demand monitoring of tumor progression. However, clinically significant capture of renal cell carcinoma CTCs (RCC-CTCs) remains elusive due to their heterogenous surface receptor expression. Herein, a novel capture platform is developed to detect RCC-CTCs through integration of dendrimer-mediated multivalent binding, a mixture of antibodies, and biomimetic cell rolling. The nanoscale binding kinetics measured using atomic force microscopy reveal that dendrimer-coated surfaces exhibit an order of magnitude enhancement in off-rate kinetics compared to surface without dendrimers, which translated into cell capture improvements by ~60%. Selectin-induced cell rolling facilitates surface recruitment of cancer cells, further improving cancer cell capture by up to 1.7-fold. Lastly, an antibody cocktail targeting four RCC-CTC surface receptors, which included epithelial cell adhesion molecule (EpCAM), carbonic anhydrase IX (CA9), epidermal growth factor receptor (EGFR), and hepatocyte growth factor receptor (c-Met), improves the capture of RCC cells by up to 80%. The optimal surface configuration outperforms the conventional assay solely relying on EpCAM, as demonstrated by detecting significantly more CTCs in patients' samples (9.8 ± 5.1 vs. 1.8 ± 2.0 CTCs mL-1). These results demonstrate that the newly engineered capture platform effectively detects RCC-CTCs for their potential use as tumor biomarkers.

Prognostic Significance of Circulating Tumor Cells with Mesenchymal Phenotypes in Patients with Gastric Cancer: A Prospective Study

BACKGROUND

Circulating tumor cells (CTCs) have been shown to be heterogeneous. Focusing on the epithelial-mesenchymal transition and perioperative kinetics, we evaluated CTCs with mesenchymal phenotypes as a potential prognostic biomarker for patients with gastric cancer.

METHODS

Peripheral blood was collected from 54 patients with gastric cancer before surgery and at 1 week and 1 month after surgery. CTCs were enriched using density-gradient centrifugation and magnetic-activated cell sorting (negative selection). Cell suspensions were characterized by multi-immunofluorescence staining against cytokeratin and N-cadherin, and by 4',6'-diamidino-2-phenyldole staining.

RESULTS

CTCs were detected in five patients (17%) with early cancer and 14 patients (56%) with advanced cancer (p < 0.05). In our system, N-cadherin, but not cytokeratin, was expressed in the CTCs of 90% (19/21) of patients. Postoperative recurrence was detected in 10 patients, all of whom had N-cadherin+/cytokeratin-/CD45- CTCs preoperatively. Regarding perioperative kinetics, we divided patients into three risk groups: a high-risk group, with one or more preoperative CTCs and increased CTCs postoperatively; an intermediate-risk group, with one or more preoperative CTCs and decreased CTCs postoperatively; and a low-risk group, with no preoperative CTCs. Recurrence rates were 57% (4/7), 33% (4/12), and 6% (2/35), respectively. The relapse-free survival rate was lower in patients at high risk versus those at intermediate or low risk, for all patients (p = 0.00024) and in patients with advanced cancer (p = 0.00103).

CONCLUSIONS

N-cadherin is a highly useful marker to detect CTCs lacking cytokeratin, and the perioperative kinetics of CTC numbers is beneficial in risk stratification for survival in patients with gastric cancer.

Pairing Microwell Arrays with an Affordable, Semiautomated Single-Cell Aspirator for the Interrogation of Circulating Tumor Cell Heterogeneity

Comprehensive analysis of tumor heterogeneity requires robust methods for the isolation and analysis of single cells from patient samples. An ideal approach would be fully compatible with downstream analytic methods, such as advanced genomic testing. These endpoints necessitate the use of live cells at high purity. A multitude of microfluidic circulating tumor cell (CTC) enrichment technologies exist, but many of those perform bulk sample enrichment and are not, on their own, capable of single-cell interrogation. To address this, we developed an affordable semiautomated single-cell aspirator (SASCA) to further enrich rare-cell populations from a specialized microwell array, per their phenotypic markers. Immobilization of cells within microwells, integrated with a real-time image processing software, facilitates the detection and precise isolation of targeted cells that have been optimally seeded into the microwells. Here, we demonstrate the platform capabilities through the aspiration of target cells from an impure background population, where we obtain purity levels of 90%-100% and demonstrate the enrichment of the target population with high-quality RNA extraction. A range of low cell numbers were aspirated using SASCA before undergoing whole transcriptome and genome analysis, exhibiting the ability to obtain endpoints from low-template inputs. Lastly, CTCs from patients with castration-resistant prostate cancer were isolated with this platform and the utility of this method was confirmed for rare-cell isolation. SASCA satisfies a need for an affordable option to isolate single cells or highly purified subpopulations of cells to probe complex mechanisms driving disease progression and resistance in patients with cancer.

Uncoupling Traditional Functionalities of Metastasis: The Parting of Ways with Real-Time Assays

The experimental evaluation of metastasis overly focuses on the gain of migratory and invasive properties, while disregarding the contributions of cellular plasticity, extra-cellular matrix heterogeneity, niche interactions, and tissue architecture. Traditional cell-based assays often restrict the inclusion of these processes and warrant the implementation of approaches that provide an enhanced spatiotemporal resolution of the metastatic cascade. Time lapse imaging represents such an underutilized approach in cancer biology, especially in the context of disease progression. The inclusion of time lapse microscopy and microfluidic devices in routine assays has recently discerned several nuances of the metastatic cascade. Our review emphasizes that a complete comprehension of metastasis in view of evolving ideologies necessitates (i) the use of appropriate, context-specific assays and understanding their inherent limitations; (ii) cautious derivation of inferences to avoid erroneous/overestimated clinical extrapolations; (iii) corroboration between multiple assay outputs to gauge metastatic potential; and (iv) the development of protocols with improved in situ implications. We further believe that the adoption of improved quantitative approaches in these assays can generate predictive algorithms that may expedite therapeutic strategies targeting metastasis via the development of disease relevant model systems. Such approaches could potentiate the restructuring of the cancer metastasis paradigm through an emphasis on the development of next-generation real-time assays.

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.

Emerging Molecular Technologies in Renal Cell Carcinoma: Liquid Biopsy

Liquid biopsy, based on the circulating tumor cells (CTCs) and cell-free nucleic acids has potential applications at multiple points throughout the natural course of cancer, from diagnosis to follow-up. The advantages of doing ctDNA assessment vs. tissue-based genomic profile are the minimal procedural risk, the possibility to serial testing in order to monitor disease-relapse and response to therapy over time and to reduce hospitalization costs during the entire process. However, some critical issues related to ctDNA assays should be taken into consideration. The sensitivity of ctDNA assays depends on the assessment technique and genetic platforms used, on tumor-organ, stage, tumor heterogeneity, tumor clonality. The specificity is usually very high, whereas the concordance with tumor-based biopsy is generally low. In patients with renal cell carcinoma (RCC), qualitative analyses of ctDNA have been performed with interesting results regarding selective pressure from therapy, therapeutic resistance, exceptional treatment response to everolimus and mutations associated with aggressive behavior. Quantitative analyses showed variations of ccfDNA levels at different tumor stage. Compared to CTC assay, ctDNA is more stable than cells and easier to isolate. Splice variants, information at single-cell level and functional assays along with proteomics, transcriptomics and metabolomics studies can be performed only in CTCs.

Dynamic changes of different phenotypic and genetic circulating tumor cells as a biomarker for evaluating the prognosis of RCC

BACKGROUND

Circulating tumor cells (CTCs) and relevant autophagy Beclin-1 genes expression are critical biomarkers for tumorigenesis and tumor progress. Here we investigated the relationship of dynamic changes of CTCs and Beclin-1 expression of CTCs with renal cell carcinoma (RCC) prognosis.

MATERIALS AND METHODS

A total of 69 patients with RCC were enrolled and divided into two groups based on the postoperative status of distant metastasis, including metastasis-free group (n = 58) and metastatic group (n = 11). Demographic characteristics of each patient were recorded in detail. All 69 enrolled patients had received multiple CTC tests and peripheral blood samples were obtained at three different time points (1 day before operation, 6 months and 12 months after operation). Peripheral blood samples were drawn before each time point and CTCs were separated by using Can Patrol CTC enrichment technique. CTCs were divided into epithelial, mesenchymal and mixed phenotype based on different surface biomarkers. RNA in situ hybridization assay was used to detect the expression of Beclin1 gene.

RESULTS

The percentages of epithelial, mesenchymal and mixed CTCs were 11.64%, 28.04% and 60.32%, respectively. There were no significant differences of initial CTCs counts between metastasis-free group (8.43 ± 5.15) and metastatic group (7.71 ± 3.82) (P > 0.05). As for metastatic group, the number of mixed CTCs at 12 months postoperatively was significantly higher than that of mixed CTCs preoperatively and 6 months postoperatively (P < 0.05). In the metastatic group, the number of Beclin1 positive CTCs was significantly higher than that of Beclin1 negative CTCs preoperatively (P < 0.05), moreover, there were several significantly changes of Beclin1 positive CTCs with different types and at different time points.

CONCLUSION

The recurrence or metastasis of RCC was uncorrelated with initial CTCs counts, but probably related with the variation trend of CTCs, especially mesenchymal CTCs and Beclin1 positive CTCs.

Cytopathological Study of the Circulating Tumor Cells filtered from the Cancer Patients' Blood using Hydrogel-based Cell Block Formation

Circulating tumor cells have emerged as biomarkers for estimating the tumor burden and metastatic potential of cancer patients. However, to date, most of studies and applications of circulating tumor cells have been conducted and applied to epithelial cancers such as breast, colorectal, and prostate tumor. The only FDA-cleared method, CellSearch, makes use of antibody against epithelial surface protein expressed on CTCs, thus obstructing wide application for various cancers with non-epithelial and semi-epithelial characteristics including renal cell carcinoma. Due to rarity and ambiguity of CTCs, designed experiment including non-biased CTC isolation and subsequent cytopathological study for finding applicable immunomarkers are urgently needed for clinical use of CTCs for less-studied cancers. Here, in order to construct the fundamental step for CTC diagnosis without limitation of its epithelial characteristics, we present the simple and novel method which incorporate both label-free CTC isolation and pathological study using hydrogel-based cell block formation. Six cell lines from lung, ovarian, kidney cancers were used to make cell block and analyzed by conventional immunocytochemical staining method to find the candidate markers for CTC. Especially for renal cancer, the physically isolated CTCs were further immunocytochemically examined with the screened candidate markers by cell block construction, and verified their clinical utility using blood samples from patients with renal cell carcinoma. This comprehensive study demonstrates that the present approach can be used to find the potential markers for any type of cancers regardless of their epithelial characteristics and isolate the specific type of CTCs in label-free manners.

Candle soot-templated silica nanobiointerface chip for detecting circulating tumour cells from patients with urologic malignancies

Liquid biopsy, known as fluid biopsy or fluid phase biopsy, is of great clinical significance in cancer diagnosis and treatment monitoring. However, traditional techniques still meet restrictions when aiming for the detection of circulating tumour cells (CTCs) with high efficiency and low cost. Herein, we applied an easily prepared silica nanobiointerface chip for detecting CTCs in prostate cancer (PCa) and clear cell renal cell carcinoma (ccRCC) patients with high efficiency. The silica nanobiointerface chip was fabricated by depositing candle soot on a glass slide, followed by chemical vapour deposition, and then by modifying anti-epithelial cell adhesion molecule (EpCAM) antibody. The silica nanobiointerface chips exhibited excellent abilities to capture PC3 PCa cell lines, with average efficiency of 81.2 ± 1.4%. We demonstrate that the strong topographic interaction between targeted cells and nanostructured surface is critical to enhancing the capture efficiency of CTCs. We further tested peripheral blood samples from 10 preoperative PCa and 7 ccRCC patients. The results show that CTCs from 7 PCa cases and 4 ccRCC cases were successfully detected. We believe that the nanobiointerface chip will provide great potential for the clinical application of CTC.

N-cadherin in cancer metastasis, its emerging role in haematological malignancies and potential as a therapeutic target in cancer

In many types of solid tumours, the aberrant expression of the cell adhesion molecule N-cadherin is a hallmark of epithelial-to-mesenchymal transition, resulting in the acquisition of an aggressive tumour phenotype. This transition endows tumour cells with the capacity to escape from the confines of the primary tumour and metastasise to secondary sites. In this review, we will discuss how N-cadherin actively promotes the metastatic behaviour of tumour cells, including its involvement in critical signalling pathways which mediate these events. In addition, we will explore the emerging role of N-cadherin in haematological malignancies, including bone marrow homing and microenvironmental protection to anti-cancer agents. Finally, we will discuss the evidence that N-cadherin may be a viable therapeutic target to inhibit cancer metastasis and increase tumour cell sensitivity to existing anti-cancer therapies.

Circulating Tumor Cells for the Management of Renal Cell Carcinoma

Renal cell carcinoma is a highly malignant cancer that would benefit from non-invasive innovative markers providing early diagnosis and recurrence detection. Circulating tumor cells are a particularly promising marker of tumor invasion that could be used to improve the management of patients with RCC. However, the extensive genetic and immunophenotypic heterogeneity of cells from RCC and their trend to transition to the mesenchymal phenotype when they circulate in blood constitute a challenge for their sensitive and specific detection. This review analyzes published studies targeting CTC in patients with RCC, in the context of the biological, pathological, and molecular complexity of this particular cancer. Although further analytical and clinical studies are needed to pinpoint the most suitable approach for highly sensitive CTC detection in RCC patients, it is clear that this field can bring a relevant guide to clinicians and help to RCC patients. Furthermore, as described, a particular subtype of RCC-the ccRCC-can be used as a model to study the relationship between cytomorphological and genetic cellular markers of malignancy, an important issue for the study of CTC from any type of solid cancer.

Treatment approaches to small renal masses in patients of advanced age (≥75 years)

The elderly population is increasing in Turkey and across the world. With the frequent use of imaging modalities, the detection rate of coincidental small renal mass has also increased. Since small renal masses are generally not malignant, most of them can be followed up by active surveillance. In the current study, we examined the treatment options that can be offered to elderly patients with small renal masses. The optimum treatment method for patients of advanced age presenting with renal masses should be determined based on the presence of comorbidities such as age, renal function, and tumor characteristics.

Single-cell genetic analysis validates cytopathological identification of circulating cancer cells in patients with clear cell renal cell carcinoma

CONTEXT

Circulating Rare Cells (CRC) are non-haematological cells circulating in blood. They include Circulating Cancer Cells (CCC) and cells with uncertain malignant features (CRC-UMF) according to cytomorphology. Clear cell renal cell carcinomas frequently bear a mutated Von Hippel-Lindau (VHL) gene.

AIM

To match blind genetic analysis of CRC and tumor samples with CRC cytopathological diagnosis.

RESULTS

29/30 patients harboured CRC (20 harboured CCC, 29 CRC-UMF) and 25/29 patients carried VHL mutations in their tumour. 205 single CRC (64 CCC, 141 CRC-UMF) provided genetic data. 57/57 CCC and 104/125 CRC-UMF from the 25 patients with VHL-mutated tumor carried the same VHL mutation detected in the tumor. Seven CCC and 16 CRC-UMF did not carry VHL mutations but were found in patients with wild-type VHL tumor tissue.

CONCLUSIONS

All the CCC and 83,2% (104/125) of the CRC-UMF were found to carry the same VHL mutation identified in the corresponding tumorous tissue, validating cytopathological identification of CCC in patients with clear cell renal cell carcinoma.

METHODS

The blood of 30 patients with clear cell renal cell carcinoma was treated by ISET® for CRC isolation, cytopathology and single-cell VHL mutations analysis, performed blindly and compared to VHL mutations of corresponding tumor tissues and leukocytes.

Circulating and disseminated tumor cells: diagnostic tools and therapeutic targets in motion

Enumeration of circulating tumor cells (CTCs) in peripheral blood with the gold standard CellSearchTM has proven prognostic value for tumor recurrence and progression of metastatic disease. Therefore, the further molecular characterization of isolated CTCs might have clinical relevance as liquid biopsy for therapeutic decision-making and to monitor disease progression. The direct analysis of systemic cancer appears particularly important in view of the known disparity in expression of therapeutic targets as well as epithelial-to-mesenchymal transition (EMT)-based heterogeneity between primary and systemic tumor cells, which all substantially complicate monitoring and therapeutic targeting at present. Since CTCs are the potential precursor cells of metastasis, their in-depth molecular profiling should also provide a useful resource for target discovery. The present review will discuss the use of systemically spread cancer cells as liquid biopsy and focus on potential target antigens.

Extracting microtentacle dynamics of tumor cells in a non-adherent environment

During metastasis, tumor cells dynamically change their cytoskeleton to traverse through a variety of non-adherent microenvironments, including the vasculature or lymphatics. Due to the challenges of imaging drift in non-adhered tumor cells, the dynamic cytoskeletal phenotypes are poorly understood. We present a new approach to analyze the dynamic cytoskeletal phenotypes of non-adhered cells that support microtentacles (McTNs), which are cell surface projections implicated in metastatic reattachment. Combining a recently-developed cell tethering method with a novel image analysis framework allowed McTN attribute extraction. Full cell outlines, number of McTNs, and distance of McTN tips from the cell body boundary were calculated by integrating a rotating anisotropic filtering method for identifying thin features with retinal segmentation and active contour algorithms. Tethered cells behave like free-floating cells; however tethering reduces cell drift and improves the accuracy of McTN measurements. Tethering cells does not significantly alter McTN number, but rather allows better visualization of existing McTNs. In drug treatment experiments, stabilizing tubulin with paclitaxel significantly increases McTN length, while destabilizing tubulin with colchicine significantly decreases McTN length. Finally, we quantify McTN dynamics by computing the time delay autocorrelations of 2 composite phenotype metrics (cumulative McTN tip distance, cell perimeter:cell body ratio). Our automated analysis demonstrates that treatment with paclitaxel increases total McTN amount and colchicine reduces total McTN amount, while paclitaxel also reduces McTN dynamics. This analysis method enables rapid quantitative measurement of tumor cell drug responses within non-adherent microenvironments, using the small numbers of tumor cells that would be available from patient samples.

Tumor Evolution, Heterogeneity, and Therapy for Our Patients With Advanced Cancer: How Far Have We Come?

The clinical and molecular heterogeneity of various cancer types is well documented. In the era of precision oncology whereby molecular profiling of tumors is incorporated into clinical care, both intra- and intertumoral molecular and genetic heterogeneity have been described. Together, they impact patient treatment and outcomes. Host genetics and the tumor microenvironment impact on tumor evolution and heterogeneity through variations in immune cell infiltration, stromal variations, and selection pressures from hypoxia or nutrient stress, among others. Tumor progression and exposure to therapeutic agents lead to further molecular evolution and heterogeneity that is clinically relevant. Moreover, tumors that evolve after diagnosis and as a function of therapy generally become more aggressive and refractory to available therapeutics, including targeted agents and immunotherapy. The evolving clinical and molecular heterogeneity of patient tumors can be explored with various clinical and research-based specimens and testing such as pre- and post-treatment biopsies; serial liquid biopsies; single cell analysis; PDX and organoid models; anatomic, functional, and molecular imaging; and rapid postmortem studies. Other factors that influence tumor heterogeneity include immune checkpoints, cancer stem cells, therapy-acquired resistance mechanisms that may occur through secondary mutations, and adaptive responses. Modern technologic advances for tumor characterization provide opportunities to understand tumor evolution and its impact on clinical outcomes to improve therapeutic regimens. Characterization of novel targets and development of effective therapeutics are needed to target heterogeneity and the evolution of resistance mechanisms.

Comparison of isolation platforms for detection of circulating renal cell carcinoma cells

Background

Analysis of circulating tumor cells (CTCs) has progressed in several tumor entities. However, little is known about CTCs in clear cell renal cell carcinoma (ccRCC) patients. Aim of our studies was to build a stable in vitro fundament for isolation of CTCs in ccRCC.

Methods

We compared the analytical performance of different CTC isolation methods with regard to yield and purity: EpCAM based enrichment, leukocyte depletion and size based enrichment. EpCAM and cytokeratin 8 (KRT8) as biomarker for CTCs expression were evaluated in ccRCC cell lines as well as clinical samples.

Results

While the EpCAM based approach failed to successfully isolate tumor cells, CD45 based approaches showed intermediate recovery rates. The cell-size based Parsortix system showed highest recovery rates. EpCAM expression was low or absent in most cell lines as well as in clinical samples, whereas KRT8 was detected as a potential biomarker in ccRCC.

Conclusion

EpCAM based approaches might miss a high number of CTCs due to low or absent expression of EpCAM in ccRCC, as shown in cell lines as well as in patient samples. We identified the cell-sized based, label independent Parsortix system to be the most effective recovery system for ccRCC CTCs.

Renal Mass and Localized Renal Cancer: AUA Guideline

PURPOSE

This AUA Guideline focuses on evaluation/counseling and management of adult patients with clinically localized renal masses suspicious for cancer, including solid-enhancing tumors and Bosniak 3/4 complex-cystic lesions.

MATERIALS AND METHODS

Systematic review utilized research from the Agency for Healthcare Research and Quality and additional supplementation by the authors and consultant methodologists. Evidence-based statements were based on body of evidence strength Grade A/B/C (Strong/Moderate/Conditional Recommendations, respectively) with additional statements presented as Clinical Principles or Expert Opinions.

RESULTS

Great progress has been made since the previous guidelines on management of localized renal masses were released (2009). The current guidelines provide updated, evidence-based recommendations regarding evaluation/counseling of patients with clinically localized renal masses, including the evolving role of renal mass biopsy. Given great variability of clinical, oncologic and functional characteristics, index patients are not utilized and the panel advocates individualized counseling/management. Management options (partial nephrectomy/radical nephrectomy/thermal ablation/active surveillance) are reviewed including recent data about comparative effectiveness and potential morbidities. Oncologic issues are prioritized while recognizing that functional outcomes are of great importance for survivorship for most patients with localized kidney cancer. A more restricted role for radical nephrectomy is recommended following well-defined selection criteria. Priority for partial nephrectomy is recommended for clinical T1a lesions, along with selective use of thermal ablation, particularly for tumors ≤3.0 cm. Important considerations for shared decision-making about active surveillance are explicitly defined.

CONCLUSIONS

Several factors should be considered during counseling/management of patients with clinically localized renal masses, including general health/comorbidities, oncologic potential of the mass, pertinent functional issues and relative efficacy/potential morbidities of various management strategies.

Current Role of Renal Biopsy in Urologic Practice

Most small renal masses (SRMs) are indolent. In fact, only approximately 80% of SRMs are malignant. Furthermore, SRMs are commonly detected in elderly and comorbid patients. Therefore, opportunities for better care intensity calibration exist. Renal mass biopsy (RMB), when appropriately used, is a valuable clinical tool to help with critical clinical decision-making in patients with SRM. This article summarizes the role of modern RMB in helping gauge care for patients with SRM.

New applications of the acridine orange fluorescence staining method: Screening for circulating tumor cells

The aim of the present study was to explore use of the acridine orange fluorescence (AO-F) staining method for screening of circulating tumor cells (CTCs) in renal cell carcinoma (RCC) patients. The AO-F positive staining rate of live and dead tumor cells was calculated. The positive staining rate in the live group was 93.4±3.0%, while the dead group failed to emit specific fluorescence. A known number of tumor cells were added to peripheral blood, and the detection sensitivity of the four groups (50, 100, 200 and 500 cells/tube) was 10.2±3.8, 9.2±2.3, 10.8±2.6 and 10.5±1.9%, respectively. The average detection sensitivity of the four groups was 10.16±2.73%. There was a positive correlation between the number of cells that was positively stained with AO-F and the total number cells in the system (χ²=0.959; P<0.001). Subsequently, the AO-F staining method was used to detect positive staining cells in 8 healthy volunteers (control group), and 112 non-metastatic and 27 metastatic RCC patients. The positive staining rate was 13.67% (19/139) in RCC patients, while none of the control group was positive. The AO-F positive staining rate was not significantly different between the metastatic and non-metastatic patients according to age, gender, the pathological pattern, T2/3 (according to the Tumor-Node-Metastasis classification) or Fuhrman grade, while there was a significant difference according to T1. The positive staining rate was 8.93% (10/112) for non-metastatic patients and 33.33% (9/27) for metastatic patients, which showed a significant difference (P<0.05). In 112 non-metastatic and 27 metastatic patients, the positive staining rate was not significantly associated with gender, age, tumor size, the pathological pattern, T classification, Fuhrman grade, the presence of a lesion or metastasis to the lungs. The present study demonstrated that the method of CTC staining with AO-F, which has high reproducibility and specificity, was feasible for identifying CTCs and warrants further study.

Circulating Tumor Cells in Genitourinary Malignancies: An Evolving Path to Precision Medicine

Precision medicine with molecularly directed therapeutics is rapidly expanding in all subspecialties of oncology. Molecular analysis and treatment monitoring require tumor tissue, but resections or biopsies are not always feasible due to tumor location, patient safety, and cost. Circulating tumor cells (CTCs) offer a safe, low-cost, and repeatable tissue source as an alternative to invasive biopsies. "Liquid biopsies" can be collected from a peripheral blood draw and analyzed to isolate, enumerate, and molecularly characterize CTCs. While there is deserved excitement surrounding new CTC technologies, studies are ongoing to determine whether these cells can provide reliable and accurate information about molecular drivers of cancer progression and inform treatment decisions. This review focuses on the current status of CTCs in genitourinary (GU) cancer. We will review currently used methodologies to isolate and detect CTCs, their use as predictive biomarkers, and highlight emerging research and applications of CTC analysis in GU malignancies.