Development of a Highly Sensitive Technique for Capturing Renal Cell Cancer Circulating Tumor Cells

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.

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.

Liquid biopsy at the frontier in renal cell carcinoma: recent analysis of techniques and clinical application

Renal cell carcinoma (RCC) is a major pathological type of kidney cancer and is one of the most common malignancies worldwide. The unremarkable symptoms of early stages, proneness to postoperative metastasis or recurrence, and low sensitivity to radiotherapy and chemotherapy pose a challenge for the diagnosis and treatment of RCC. Liquid biopsy is an emerging test that measures patient biomarkers, including circulating tumor cells, cell-free DNA/cell-free tumor DNA, cell-free RNA, exosomes, and tumor-derived metabolites and proteins. Owing to its non-invasiveness, liquid biopsy enables continuous and real-time collection of patient information for diagnosis, prognostic assessment, treatment monitoring, and response evaluation. Therefore, the selection of appropriate biomarkers for liquid biopsy is crucial for identifying high-risk patients, developing personalized therapeutic plans, and practicing precision medicine. In recent years, owing to the rapid development and iteration of extraction and analysis technologies, liquid biopsy has emerged as a low cost, high efficiency, and high accuracy clinical detection method. Here, we comprehensively review liquid biopsy components and their clinical applications over the past 5 years. Additionally, we discuss its limitations and predict its future prospects.

Antibody-Based Therapeutics for the Treatment of Renal Cell Carcinoma: Challenges and Opportunities

Renal cell carcinoma (RCC) is among the top 10 most common cancers in both men and women with an estimated 75 000 cases each year in the US. Over the last decade, the therapeutic landscape for patients with metastatic RCC has significantly evolved, with immunotherapy emerging as the new front-line therapy. Despite significant improvement in toxicity profile and survival outcomes, key concerns such as patient selection, treatment sequencing, and intrinsic and acquired resistance remain unresolved. Emerging options such as antibody-based therapeutics (eg, anti-CD70, anti-CA9, and anti-ENPP3) are being explored in clinical trials for patients with cancer resistant or refractory to current immunotherapies. Despite positive results for hematological cancers, breast cancer, and more recently bladder cancer, most antibody-based therapies failed to improve the outcomes in patients with advanced RCC. This underscores the need to understand the underlying causes of failed responses to this treatment class, which will ultimately support the rational design of more effective and tolerable treatments. In this review, we summarize the evolving landscape of RCC therapeutics and describe recent clinical trials with emerging antibody-based therapeutics. We also describe the challenges that need to be overcome for the successful creation of therapeutic antibodies for treating 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.

Clinical significance of circulating tumour cells and Ki-67 in renal cell carcinoma

Background

Renal cell carcinoma (RCC) is a common malignant tumour of the genitourinary system. We aimed to analyse the potential value of metastasis-related biomarkers, circulating tumour cells (CTCs) and the proliferative marker Ki-67 in the diagnosis of RCC.

Methods

Data from 24 laparoscopic radical nephrectomies (RNs) and 17 laparoscopic partial nephrectomies (PNs) were collected in 2018. The numbers and positive rates of CTCs and circulating tumour microemboli (CTM) in the peripheral blood were obtained at three different time points: just before surgery, immediately after surgery and 1 week after surgery. Ki-67 protein expression was evaluated in the RCC tissue by immunohistochemistry.

Results

Except for the statistically significant association between the preoperative CTC counts and tumour size, no association between the number and positive rate of perioperative CTCs and clinicopathological features was found. The CTC counts gradually decreased during the perioperative period, and at 1 week after surgery, they were significantly lower than those before surgery. High Ki-67 expression was significantly positively correlated with preoperative CTC counts. In addition, Ki-67 expression was higher in the high CTC group (≥ 5 CTCs).

Conclusion

Our results suggest that surgical nephrectomy is associated with a decrease in CTC counts in RCC patients. CTCs can act as a potential biomarker for the diagnosis and prognosis of RCC. A careful and sufficient long-term follow-up is needed for patients with high preoperative CTC counts.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-021-02268-5.

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.

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.

The Role of Proteoglycans in Cancer Metastasis and Circulating Tumor Cell Analysis

Circulating tumor cells (CTCs) are accessible by liquid biopsies via an easy blood draw. They represent not only the primary tumor site, but also potential metastatic lesions, and could thus be an attractive supplement for cancer diagnostics. However, the analysis of rare CTCs in billions of normal blood cells is still technically challenging and novel specific CTC markers are needed. The formation of metastasis is a complex process supported by numerous molecular alterations, and thus novel CTC markers might be found by focusing on this process. One example of this is specific changes in the cancer cell glycocalyx, which is a network on the cell surface composed of carbohydrate structures. Proteoglycans are important glycocalyx components and consist of a protein core and covalently attached long glycosaminoglycan chains. A few CTC assays have already utilized proteoglycans for both enrichment and analysis of CTCs. Nonetheless, the biological function of proteoglycans on clinical CTCs has not been studied in detail so far. Therefore, the present review describes proteoglycan functions during the metastatic cascade to highlight their importance to CTCs. We also outline current approaches for CTC assays based on targeting proteoglycans by their protein cores or their glycosaminoglycan chains. Lastly, we briefly discuss important technical aspects, which should be considered for studying proteoglycans.

Update on Circulating Tumor Cells in Genitourinary Tumors with Focus on Prostate Cancer

Current developments in the treatment of genitourinary tumors underline the unmet clinical need for biomarkers to improve decision-making in a challenging clinical setting. The detection of circulating tumor cells (CTCs) has become one of the most exciting and important new approaches to identifying biomarkers at different stages of disease in a non-invasive way. Potential applications of CTCs include monitoring treatment efficacy and early detection of progression, selecting tailored therapies, as well as saving treatment costs. However, despite the promising implementation of CTCs in a clinical scenario, the isolation and characterization of these cells for molecular studies remain expensive with contemporary platforms, and significant technical challenges still need to be overcome. This updated, critical review focuses on the state of CTCs in patients with genitourinary tumor with focus on prostate cancer, discussing technical issues, main clinical results and hypothesizing potential future perspectives in clinical scenarios.

Spindle cell renal cell carcinoma diagnosed after sunitinib treatment for chromophobe renal cell carcinoma

INTRODUCTION

Chromophobe renal cell carcinoma presents in early pathological stages with a lower risk of metastasis. However, aggressive features and metastasis can occur. A rare case of rapidly progressive disease with histological changes is presented.

CASE PRESENTATION

A 56-year-old woman had a right renal tumor with multiple lymph node metastases, and the pathological diagnosis of the biopsy specimens from the primary tumor was chromophobe renal cell carcinoma. After sunitinib treatment, the metastatic lymph node had decreased in size and the numbers of circulating tumor cells were decreased, consequently, cytoreductive nephrectomy was performed. However, rapid progression of lymph node metastases was observed. Histopathological examination showed that the renal tumor was diagnosed as spindle cell renal carcinoma.

CONCLUSION

It appears that the primary tumor underwent epithelial-mesenchymal transition; further tissue specimen collection and analysis might be needed.