Circulating tumor cell detection in high-risk non-metastatic prostate cancer

Dissemination of Circulating Tumor Cells in Breast and Prostate Cancer: Implications for Early Detection

Burgeoning evidence suggests that circulating tumor cells (CTCs) may disseminate into blood vessels at an early stage, seeding metastases in various cancers such as breast and prostate cancer. Simultaneously, the early-stage CTCs that settle in metastatic sites [termed disseminated tumor cells (DTCs)] can enter dormancy, marking a potential source of late recurrence and therapy resistance. Thus, the presence of these early CTCs poses risks to patients but also holds potential benefits for early detection and treatment and opportunities for possibly curative interventions. This review delves into the role of early DTCs in driving latent metastasis within breast and prostate cancer, emphasizing the importance of early CTC detection in these diseases. We further explore the correlation between early CTC detection and poor prognoses, which contribute significantly to increased cancer mortality. Consequently, the detection of CTCs at an early stage emerges as a critical imperative for enhancing clinical diagnostics and allowing for early interventions.

Research progress of CTC, ctDNA, and EVs in cancer liquid biopsy

Circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), and extracellular vehicles (EVs) have received significant attention in recent times as emerging biomarkers and subjects of transformational studies. The three main branches of liquid biopsy have evolved from the three primary tumor liquid biopsy detection targets-CTC, ctDNA, and EVs-each with distinct benefits. CTCs are derived from circulating cancer cells from the original tumor or metastases and may display global features of the tumor. ctDNA has been extensively analyzed and has been used to aid in the diagnosis, treatment, and prognosis of neoplastic diseases. EVs contain tumor-derived material such as DNA, RNA, proteins, lipids, sugar structures, and metabolites. The three provide different detection contents but have strong complementarity to a certain extent. Even though they have already been employed in several clinical trials, the clinical utility of three biomarkers is still being studied, with promising initial findings. This review thoroughly overviews established and emerging technologies for the isolation, characterization, and content detection of CTC, ctDNA, and EVs. Also discussed were the most recent developments in the study of potential liquid biopsy biomarkers for cancer diagnosis, therapeutic monitoring, and prognosis prediction. These included CTC, ctDNA, and EVs. Finally, the potential and challenges of employing liquid biopsy based on CTC, ctDNA, and EVs for precision medicine were evaluated.

Application of microfluidic technology based on surface-enhanced Raman scattering in cancer biomarker detection: A review

With the continuous discovery and research of predictive cancer-related biomarkers, liquid biopsy shows great potential in cancer diagnosis. Surface-enhanced Raman scattering (SERS) and microfluidic technology have received much attention among the various cancer biomarker detection methods. The former has ultrahigh detection sensitivity and can provide a unique fingerprint. In contrast, the latter has the characteristics of miniaturization and integration, which can realize accurate control of the detection samples and high-throughput detection through design. Both have the potential for point-of-care testing (POCT), and their combination (lab-on-a-chip SERS (LoC-SERS)) shows good compatibility. In this paper, the basic situation of circulating proteins, circulating tumor cells, exosomes, circulating tumor DNA (ctDNA), and microRNA (miRNA) in the diagnosis of various cancers is reviewed, and the detection research of these biomarkers by the LoC-SERS platform in recent years is described in detail. At the same time, the challenges and future development of the platform are discussed at the end of the review. Summarizing the current technology is expected to provide a reference for scholars engaged in related work and interested in this field.

Circulating tumour cells for early detection of clinically relevant cancer

Given that cancer mortality is usually a result of late diagnosis, efforts in the field of early detection are paramount to reducing cancer-related deaths and improving patient outcomes. Increasing evidence indicates that metastasis is an early event in patients with aggressive cancers, often occurring even before primary lesions are clinically detectable. Metastases are usually formed from cancer cells that spread to distant non-malignant tissues via the blood circulation, termed circulating tumour cells (CTCs). CTCs have been detected in patients with early stage cancers and, owing to their association with metastasis, might indicate the presence of aggressive disease, thus providing a possible means to expedite diagnosis and treatment initiation for such patients while avoiding overdiagnosis and overtreatment of those with slow-growing, indolent tumours. The utility of CTCs as an early diagnostic tool has been investigated, although further improvements in the efficiency of CTC detection are required. In this Perspective, we discuss the clinical significance of early haematogenous dissemination of cancer cells, the potential of CTCs to facilitate early detection of clinically relevant cancers, and the technological advances that might improve CTC capture and, thus, diagnostic performance in this setting.

Baseline CTC Count as a Predictor of Long-Term Outcomes in High-Risk Prostate Cancer

The aim of the present study was to verify whether the baseline circulating tumor cell (CTC) count might serve as a predictor of overall survival (OS) and metastasis-free survival (MFS) in patients with high-risk prostate cancer (PCa) during a follow-up period of at least 5 years. CTCs were enumerated using three different assay formats in 104 patients: the CellSearch® system, EPISPOT assay and GILUPI CellCollector. A total of 57 (55%) patients survived until the end of the follow-up period, with a 5 year OS of 66% (95% CI: 56–74%). The analysis of univariate Cox proportional hazard models identified a baseline CTC count ≥ 1, which was determined with the CellSearch® system, a Gleason sum ≥ 8, cT ≥ 2c and metastases at initial diagnosis as significant predictors of a worse OS in the entire cohort. The CTC count ≥ 1 was also the only significant predictor of a worse OS in a subset of 85 patients who presented with localized PCa at the baseline. The baseline CTC number did not affect the MFS. In conclusion, the baseline CTC count can be considered a determinant of survival in high-risk PCa and also in patients with a localized disease. However, determining the prognostic value of the CTC count in patients with localized PCa would optimally require longitudinal monitoring of this parameter.

Liquid Biopsy in Diagnosis and Prognosis of Non-Metastatic Prostate Cancer

Currently, sensitive and specific methods for the detection and prognosis of early stage PCa are lacking. To establish the diagnosis and further identify an appropriate treatment strategy, prostate specific antigen (PSA) blood test followed by tissue biopsy have to be performed. The combination of tests is justified by the lack of a highly sensitive, specific, and safe single test. Tissue biopsy is specific but invasive and may have severe side effects, and therefore is inappropriate for screening of the disease. At the same time, the PSA blood test, which is conventionally used for PCa screening, has low specificity and may be elevated in the case of noncancerous prostate tumors and inflammatory conditions, including benign prostatic hyperplasia and prostatitis. Thus, diverse techniques of liquid biopsy have been investigated to supplement or replace the existing tests of prostate cancer early diagnosis and prognostics. Here, we provide a review on the advances in diagnosis and prognostics of non-metastatic prostate cancer by means of various biomarkers extracted via liquid biopsy, including circulating tumor cells, exosomal miRNAs, and circulating DNAs.

Isolation of Circulating Tumor Cells from Seminal Fluid of Patients with Prostate Cancer Using Inertial Microfluidics

Simple Summary

Prostate cancer (PCa) is notoriously difficult to diagnose owing to the lack of reliable biomarkers and the invasiveness of obtaining a tissue biopsy from the prostate. As an alternative, we developed a liquid biopsy technique, based on isolating tumor cells from semen samples via a microfluidic device. To optimize the device, we first attempted to recover PCa cells from semen samples spiked with PCa cell lines, achieving an average efficiency of >87% cell recovery at the chosen flow rate. We then transitioned to a clinical setting using semen samples from PCa patients. The yield of isolated clinical PCa cells varied between 67 and 307 cells per mL of semen (in 15 cancer patients). These cells were stained and compared to the standard prognostic parameters such as Gleason score and PSA serum level. This study presents a potential liquid biopsy technique to augment the existing diagnosis and prognosis of PCa.

Abstract

Prostate cancer (PCa) diagnosis is primarily based on prostate-specific antigen (PSA) testing and prostate tissue biopsies. However, PSA testing has relatively low specificity, while tissue biopsies are highly invasive and have relatively low sensitivity at early stages of PCa. As an alternative, we developed a technique of liquid biopsy, based on isolation of circulating tumor cells (CTCs) from seminal fluid (SF). The recovery of PCa cells from SF was demonstrated using PCa cell lines, achieving an efficiency and throughput as high as 89% (±3.8%) and 1.7 mL min⁻¹, respectively, while 99% (±0.7%) of sperm cells were disposed of. The introduced approach was further tested in a clinical setting by collecting and processing SF samples of PCa patients. The yield of isolated CTCs measured as high as 613 cells per SF sample in comparison with that of 6 cells from SF of healthy donors, holding significant promise for PCa diagnosis. The correlation analysis of the isolated CTC numbers with the standard prognostic parameters such as Gleason score and PSA serum level showed correlation coefficient values at 0.40 and 0.73, respectively. Taken together, our results show promise in the developed liquid biopsy technique to augment the existing diagnosis and prognosis of PCa.

Fast, Reusable, Cell Uniformly Distributed Membrane Filtration Device for Separation of Circulating Tumor Cells

Isolation of circulating tumor cells (CTCs) is of great significance for the diagnosis, prognosis, and treatment of metastatic cancer. Among CTC capture methods independent of antibodies, membrane filtration-based methods have the advantages of simplicity, rapidity, and high throughput but usually have problems such as clogging, high pressure drop, and impaired cell viability. In this study, we designed and tested a reusable device that used horizontal rotor and fluid-assisted separation to capture CTCs by centrifugal membrane filtration, achieving simple, fast, highly efficient, and viable cell capture on traditional centrifuge. The average capture efficiency was 95.8% for different types of cancer cells with >90% survival, and the removal of white blood cells can reach 99.72% under four times cleaning of the membrane after filtration. A further clinic demo was performed using the device to detect residual leukemic cells in patients; the results showed a 10-fold enrichment of the leukemic cells in peripheral blood samples. Taken together, the simple, robust, and efficient CTC capture device may have the potential for clinic routine detection and analysis of circulating tumor cells.

Circulating tumor cells in patients undergoing androgen deprivation therapy with versus without cryosurgery for metastatic prostate cancer: a retrospective analysis

BACKGROUND

The study aimed to assess the value of circulating tumor cells (CTCs) as a prognostic and treatment response marker in patients undergoing androgen deprivation therapy (ADT) plus cryosurgery vs. ADT alone for metastatic prostate cancer (mPCA).

METHODS

This retrospective analysis included 43 patients with mPCA: 23 receiving ADT alone (control) and 20 receiving additional cryosurgery (cryosurgery group). CTCs and progression-free survival (PFS) were compared between the two groups. Cox proportional hazards regression was conducted to identify variables associated with PFS.

RESULTS

Median PFS was 35 months (IQR, 33‑37) in the cryosurgery group vs. 30 months (IQR, 27‑32) in the control (p < 0.001). CTCs count was significantly lower in the cryosurgery group at both 3 months (z = 2.170, p = 0.030) and 12 months (z = 2.481; p = 0.013). In comparison to the baseline, the number of CTCs at both 3 and 12 months was lower in the cryosurgery group (p = 0.004 and p < 0.001, respectively), but not in the ADT alone group. In multivariate Cox regression, shorter PFS was associated with baseline PSA ≧100 ng/ml (HR 6.584, 95% CI, 5.309‑8.166), biopsy Gleason score ≧ 8 (HR 2.064, 95% CI, 1.608‑2.650), clinic T stage>T2b (HR 5.021, 95% CI, 3.925‑6.421), number of bone metastases>3 (HR 3.421, 95% CI, 2.786‑4.202), positive CTCs at 3 months post-treatment (HR 6.833, 95% CI, 5.176‑9.022), positive CTCs 1 year post-treatment (HR 6.051, 95% CI, 4.347‑8.424). Prostate cryosurgery was associated with longer PFS (HR 0.062, 95% CI, 0.048‑.080).

CONCLUSIONS

CTC was a prognostic and treatment response marker for mPCA. ADT plus cryosurgery could reduce CTCs and prolong PFS vs. ADT alone in mPCA patients with low metastatic volume.

Application of Primary/Secondary Circulating Tumor Cells for the Prediction of Biochemical Recurrence in Nonmetastatic Prostate Cancer Patients following Radical Prostatectomy or Radiotherapy: A Meta-Analysis

Background

Circulating tumor cells (CTCs) have been regarded as an independent prognostic marker for metastatic castration-resistant prostate cancer (mCRPC). Its prognostic value, however, in nonmetastatic prostate cancer (NMPC) is still unclear.

Purpose

To elucidate whether CTCs can predict the biochemical recurrence (BCR) in NMPC patients following radical prostatectomy (RP) or radiotherapy (RT).

Methods

PubMed, Cochrane Database, and Embase and the references in relevant studies were systematically searched. Studies that investigated the correlation of CTCs and BCR in NMPC patients after RP or RT were identified and reviewed. Overall odds ratio (OR) of BCR in such patients with/without CTCs was pooled. We also calculated and pooled overall prevalence of BCR in such CTC-positive patients.

Results

In total, 12 studies comprising 1917 participants were eligible for the meta-analysis and showed that the presence of secondary circulating tumor cells (SCTCs) is associated with a higher BCR rate of 59% (95% CI: 22%-88%) in patients with NMPC after RP or RT (OR = 6.12; 95% CI: 2.22-16.85; P < 0.001). However, regardless of the presence of primary circulating tumor cells (PCTCs), it has not been shown to be associated with higher BCR.

Conclusions

Our research demonstrated that SCTC-positive patients are associated with higher BCR compared to SCTC-negative patients in NMPC. Therefore, it is recommended that NMPC patients undergo CTC surveillance intensively after RP or RT.

Clinical Relevance of Circulating Tumor Cells in Prostate Cancer Management

Given the low specificity of the routinely used biomarker prostate-specific antigen, circulating tumor cell (CTC) enumeration seems to be particularly useful in the monitoring of prostate cancer. In this review, we focused on a few aspects of CTC enumeration in prostate malignancies: prognostic value in metastatic and non-metastatic tumors, role in the monitoring of treatment outcomes, use as a surrogate marker for survival, and other applications, mostly for research purposes. CTC enumeration, without a doubt, offers an attractive perspective in the management of prostate cancer. However, the vast majority of available data about the role of CTC in this malignancy originate from randomized studies of anticancer agents and do not necessarily translate into real-world clinical practice. Further, most studies on the application of CTC in prostate cancer patients were limited to advanced stages of this malignancy. Meanwhile, the role of CTC in the early stages of prostate cancer, in which some patients may present with occult disseminated disease, is still relatively poorly understood, and should thus be studied extensively. Other obstacles in the widespread application of CTC enumeration in routine clinical practice include considerable discrepancies in the number of cells determined with various commercially available systems.

Clinical utility of circulating tumor cells: an update

The prognostic role of circulating tumor cells (CTCs) has been clearly demonstrated in many types of cancer. However, their roles in diagnostic and treatment strategies remain to be defined. In this review, we present an overview of the current clinical validity of CTCs in nonmetastatic and metastatic cancer, and the main studies or concepts investigating the clinical utility of CTCs. In particular, we focus on breast, lung, colorectal, and prostate cancer. Two major topics concerning the clinical utility of CTC are discussed: treatment based on CTC count or CTC variations, and treatment based on the molecular characteristics of CTCs. Although some of these studies are inconclusive, many are still ongoing, and their results could help to define the role of CTCs in the management of cancers. A summary of published or ongoing phase II-III trials is also presented.

Aptamer-based nanostructured interfaces for the detection and release of circulating tumor cells

Analysis of circulating tumor cells (CTCs) can provide significant clinical information for tumors, which has proven to be helpful for cancer diagnosis, prognosis monitoring, treatment efficacy, and personalized therapy. However, CTCs are an extremely rare cell population, which challenges the isolation of CTCs from patient blood. Over the last few decades, many strategies for CTC detection have been developed based on the physical and biological properties of CTCs. Among them, nanostructured interfaces have been widely applied as CTC detection platforms to overcome the current limitations associated with CTC capture. Furthermore, aptamers have attracted significant attention in the detection of CTCs due to their advantages, including good affinity, low cost, easy modification, excellent stability, and low immunogenicity. In addition, effective and nondestructive release of CTCs can be achieved by aptamer-mediated methods that are used under mild conditions. Herein, we review some progress in the detection and release of CTCs through aptamer-functionalized nanostructured interfaces.

A novel microfluidic device integrating focus-separation speed reduction design and trap arrays for high-throughput capture of circulating tumor cells

Isolation and analysis of circulating tumor cells (CTCs) from peripheral blood provides a potential way to detect and characterize cancer. Existing technologies to separate or capture CTCs from whole blood still have issues with sample throughput, separation efficiency or stable efficiency at different flow rates. Here, we proposed a new concept to capture rare CTCs from blood by integrating a triangular prism array-based capture apparatus with streamline-based focus-separation speed reduction design. The focus-separation design could focus and maintain CTCs, while removing a considerable proportion of liquid (98.9%) containing other blood cells to the outlet, therefore, a high CTC capture efficiency could be achieved in the trap arrays with a high initial flow rate. It is worth mentioning that the new design works well over a wide range of flow rates, so it does not require the stability of the flow rate. The results showed that this novel integrated chip can achieve a sample throughput from 5 to 40 mL h-1 with a stable and high CTC capture efficiency (up to 94.8%) and high purity (up to 4 log white blood cells/WBC depletion). The clinical experiment showed that CTCs including CTC clusters were detected in 11/11 (100.0%) patients (mean = 31 CTCs mL-1, median = 25 CTCs mL-1). In summary, our chip enriches and captures CTCs based on physical properties, and it is simple, cheap, fast, and efficient and has low requirements on flow rate, which is very suitable for large-scale application of CTC testing in clinics.

The Clinical Application and Potential Roles of Circulating Tumor Cells in Bladder Cancer and Prostate Cancer

Circulating tumor cells (CTCs) are considered to be promising biomarkers in malignant diseases. Recently, molecular profiles of CTCs in prostate cancer (PCa) and the role of CTCs in neoadjuvant chemotherapy and transurethral resections of bladder cancer (BCa) are intensely studied. However, localized PCa and nonmuscle-invasive BCa are less investigated and discussed. Moreover, the benefit and feasibility of clinical applications of CTCs should be critically questioned and reevaluated. This review focuses mainly on clinical issues and lesser on methodologies, and summarizes the quintessence of available works dealing with clinical applications of CTCs in PCa and BCa management.

Genome‑wide copy number analysis of circulating tumor cells in breast cancer patients with liver metastasis

The genome‑wide copy number analysis of circulating tumor cells (CTCs) provides a promising prognostic biomarker for survival in breast cancer liver metastasis (BCLM) patients. The present study aimed to confirm the prognostic value of the presence of CTCs in BCLM patients. We previously developed an assay for the genome‑wide pattern differences in copy number variations (CNVs) as an adjunct test for the routine imaging and histopathologic diagnosis methods to distinguish newly diagnosed liver metastases and recurrent liver metastases. Forty‑three breast cancer patients were selected for this study in which 23 newly diagnosed and 20 recurrent liver metastases were diagnosed by histopathology and 18F‑FDG PET/CT imaging. CTCs were counted from all patients using the CellSearch system and were confirmed by cytomorphology and three‑color immunocytochemistry. Genomic DNA of single CTCs was amplified using multiple annealing and looping based amplification cycles (MALBAC). Then, we compared the CTC numbers of newly diagnosed and recurrent BCLM patients using Illumina platforms. A high CTC frequency (>15 CTCs/7.5 ml blood) was found to be correlated with disease severity and metastatic progression, which suggests the value for CTCs in the diagnosis of BCLM in comparison with pathohistology and PET/CT imaging (P>0.05). Moreover, CTCs isolated from BCLM patients remained an independent prognostic detection factor associated with overall survival (P=0.0041). Comparison between newly diagnosed and recurrent liver metastases revealed different frequencies of CNVs (P>0.05). Notably, the CNV pattern of isolated CTCs of recurrent BCLM patients was similar to recurrent liver metastases (nearly 82% of the gain/loss regions). Functional enrichment analysis identified 25 genes as a CNV signature of BCLM. Among them, were defensin and β‑defensin genes, which are significantly associated with anti‑angiogenesis and immunomodulation signaling pathways. High CTC frequencies are effective in the evaluation and differentiation between newly diagnosed liver metastases from recurrent liver metastases. Future clinical studies will be necessary to fully determine the prognostic potential of CTC cluster signatures in patients with BCLM.

Prospective Study of the Clinical Impact of Epithelial and Mesenchymal Circulating Tumor Cells in Localized Prostate Cancer

Background

Although circulating tumor cells (CTCs) are considered as a surrogate marker in monitoring disease progression and treatment response in late stage prostate cancer (PCa), its clinical impact in localized PCa remains unclear, indicating the limitation that is simply based on cell count. This perspective observational study aimed to detect the epithelial-to-mesenchymal transition (EMT) subtypes of CTCs in localized PCa and analyze their clinical relevance and application in predicting PCa stages before surgery compared with the Partin table.

Patients and Methods

Between August 2017 and April 2019, 80 newly diagnosed localized PCa patients were enrolled in the study. Peripheral blood samples (5 mL) were collected prior to surgery. The CanPatrol^TM CTC enrichment technique, a size-based isolation method, was used to detect the EMT CTCs. Clinical relevance of the CTCs was analyzed with Spearman’s rank correlation test. Models to predict pathological were built with multivariate logistic regression. Receiver operating characteristic (ROC) curve and area under the curve (AUC) analysis were performed to evaluate the accuracy of the prediction model.

Results

CTCs were detected in 55% of all patients. The biophenotypic CTCs were most valuable and closely correlated with PSA, Gleason score, D’Amico risk classification, and pathological stage in localized PCa. The mesenchymal subtype was rare in this population but associated with seminal vesicle invasion, while the epithelial subtype had limited clinical significance. In addition, the biophenotypic CTCs combined with traditional clinical variables were analyzed by multivariate logistic regression to predict organ-confined disease before surgery, of which the AUC reached 0.818 and was superior to the Partin table 2017 in our cohort.

Conclusion

This study highlights the clinical impact of the biophenotypic CTCs in localized PCa, which was most closely related to clinical variables and could help to predict pathology outcomes before surgery.

Detection and dynamics of circulating tumor cells in patients with high-risk prostate cancer treated with radiotherapy and hormones: a prospective phase II study

BACKGROUND

Circulating tumor cells (CTCs) are an established prognostic marker in castration-resistant prostate cancer but have received little attention in localized high-risk disease. We studied the detection rate of CTCs in patients with high-risk prostate cancer before and after androgen deprivation therapy and radiotherapy to assess its value as a prognostic and monitoring marker.

PATIENTS AND METHODS

We performed a prospective analysis of CTCs in the peripheral blood of 65 treatment-naïve patients with high-risk prostate cancer. EpCAM-positive CTCs were enumerated using the CELLSEARCH system at 4 timepoints. A cut off of 0 vs ≥ 1 CTC/7.5 ml blood was defined as a threshold for negative versus positive CTCs status.

RESULTS

CTCs were detected in 5/65 patients (7.5%) at diagnosis, 8/62 (12.9%) following neoadjuvant androgen deprivation and 11/59 (18.6%) at the end of radiotherapy, with a median CTC count/7.5 ml of 1 (range, 1-136). Only 1 patient presented a positive CTC result 9 months after radiotherapy. Positive CTC status (at any timepoint) was not significantly associated with any clinical or pathologic factors. However, when we analyzed variations in CTC patterns following treatment, we observed a significant association between conversion of CTCs and stages T3 (P = 0.044) and N1 (P = 0.002). Detection of CTCs was not significantly associated with overall survival (P > 0.40).

CONCLUSIONS

Our study showed a low detection rate for CTCs in patients with locally advanced high-risk prostate cancer. The finding of a de novo positive CTC count after androgen deprivation therapy is probably due to a passive mechanism associated with the destruction of the tumor. Further studies with larger samples and based on more accurate detection of CTCs are needed to determine the potential prognostic and therapeutic value of this approach in non-metastatic prostate cancer.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT01800058.

Circulating ensembles of tumor-associated cells: A redoubtable new systemic hallmark of cancer

Circulating ensembles of tumor‐associated cells (C‐ETACs) which comprise tumor emboli, immune cells and fibroblasts pose well‐recognized risks of thrombosis and aggressive metastasis. However, the detection, prevalence and characterization of C‐ETACs have been impaired due to methodological difficulties. Our findings show extensive pan‐cancer prevalence of C‐ETACs on a hitherto unreported scale in cancer patients and virtual undetectability in asymptomatic individuals. Peripheral blood mononuclear cells (PBMCs) were isolated from blood samples of 16,134 subjects including 5,509 patients with epithelial malignancies in various organs and 10,625 asymptomatic individuals with age related higher cancer risk. PBMCs were treated with stabilizing reagents to protect and harvest apoptosis‐resistant C‐ETACs, which are defined as cell clusters comprising at least three EpCAM⁺ and CK⁺ cells irrespective of leucocyte common antigen (CD45) status. All asymptomatic individuals underwent screening investigations for malignancy including PAP smear, mammography, low‐dose computed tomography, evaluation of cancer antigen 125, cancer antigen 19‐9, alpha fetoprotein, carcinoembryonic antigen, prostate specific antigen (PSA) levels and clinical examination to identify healthy individuals with no indication of cancer. C‐ETACs were detected in 4,944 (89.8%, 95% CI: 89.0–90.7%) out of 5,509 cases of cancer. C‐ETACs were detected in 255 (3%, 95% CI: 2.7–3.4%) of the 8,493 individuals with no abnormal findings in screening. C‐ETACs were detected in 137 (6.4%, 95% CI: 5.4–7.4%) of the 2,132 asymptomatic individuals with abnormal results in one or more screening tests. Our study shows that heterotypic C‐ETACs are ubiquitous in epithelial cancers irrespective of radiological, metastatic or therapy status. C‐ETACs thus qualify to be a systemic hallmark of cancer.

What's new?

Circulating Ensembles of Tumor Associated Cells (C‐ETACs) comprised of tumor emboli, immune cells, and fibroblasts pose well‐recognized risks of thrombosis and aggressive metastasis. However, the detection and characterization of C‐ETACs have been impaired by methodological difficulties. Here, the authors have developed a label‐free non‐mechanical process that permits enrichment of viable apoptosis‐resistant C‐ETACs from peripheral blood. They show that heterotypic C‐ETACs are not merely incidental findings in cancer but rather a systemic manifestation of malignancy. C‐ETACs are present in a significant proportion of all solid organ malignancies and are rare in asymptomatic individuals. Monitoring of C‐ETACs could help inform cancer management.

In Vivo Detection of Circulating Tumor Cells in High-Risk Non-Metastatic Prostate Cancer Patients Undergoing Radiotherapy

High-risk non-metastatic prostate cancer (PCa) has the potential to progress into lethal disease. Treatment options are manifold but, given a lack of surrogate biomarkers, it remains unclear which treatment offers the best results. Several studies have reported circulating tumor cells (CTCs) to be a prognostic biomarker in metastatic PCa. However, few reports on CTCs in high-risk non-metastatic PCa are available. Herein, we evaluated CTC detection in high-risk non-metastatic PCa patients using the in vivo CellCollector CANCER01 (DC01) and CellSearch system. CTC counts were analyzed and compared before and after radiotherapy (two sampling time points) in 51 high-risk non-metastatic PCa patients and were further compared according to isolation technique; further, CTC counts were correlated to clinical features. Use of DC01 resulted in a significantly higher percentage of CTC-positive samples compared to CellSearch (33.7% vs. 18.6%; p = 0.024) and yielded significantly higher CTC numbers (range: 0-15 vs. 0-5; p = 0.006). Matched pair analysis of samples between two sampling time points showed no difference in CTC counts determined by both techniques. CTC counts were not correlated with clinicopathological features. In vivo enrichment using DC01 has the potential to detect CTC at a higher efficiency compared to CellSearch, suggesting that CTC is a suitable biomarker in high-risk non-metastatic PCa.

Clinical Impact of Circulating Tumor Cells in Patients with Localized Prostate Cancer

The main issue concerning localized prostate cancers is the lack of a suitable marker which could help patients’ stratification at diagnosis and distinguish those with a benign disease from patients with a more aggressive cancer. Circulating Tumor Cells (CTC) are spread in the blood by invasive tumors and could be the ideal marker in this setting. Therefore, we have compiled data from the literature in order to obtain clues about the clinical impact of CTC in patients with localized prostate cancer. Forty-three publications have been found reporting analyses of CTC in patients with non-metastatic prostate cancer. Of these, we have made a further selection of 11 studies targeting patients with clinical or pathological stages T1 and T2 and reporting the clinical impact of CTC. The results of this search show encouraging data toward the use of CTC in patients with early-stage cancer. However, they also highlight the lack of standardized methods providing a highly sensitive and specific approach for the detection of prostate-derived CTC.

Analysis of Circulating Tumor Cells in Patients with Non-Metastatic High-Risk Prostate Cancer before and after Radiotherapy Using Three Different Enumeration Assays

The characterization of circulating tumor cells (CTCs) can lead to a promising strategy for monitoring residual or relapsing prostate cancer (PCa) after local therapy. The aim of this study was to compare three innovative technologies for CTC enumeration in 131 high-risk patients with PCa, before and after radiotherapy, combined with androgen deprivation. The CTC number was tested using the FDA-cleared CellSearch^® system, the dual fluoro-EPISPOT assay that only detects functional CTCs, and the in vivo CellCollector^® technology. The highest percentage of CTC-positive patients was detected with the CellCollector^® (48%) and dual fluoro-EPISPOT (42%) assays, while the CellSearch^® system presented the lowest rate (14%). Although the concordance among methods was only 23%, the cumulative positivity rate was 79%. A matched-pair analysis of the samples before, and after, treatment suggested a trend toward a decrease in CTC count after treatment with all methods. CTC tended to be positivity correlated with age for the fluoro-EPISPOT assay and with PSA level from the data of three assays. Combining different CTC assays improved CTC detection rates in patients with non-metastatic high-risk PCa before and after treatment. Our findings do not support the hypothesis that radiotherapy leads to cancer cell release in the circulation.

Enumeration and Changes in Circulating Tumor Cells and Their Prognostic Value in Patients Undergoing Cytoreductive Radical Prostatectomy for Oligometastatic Prostate Cancer-Translational Research Results from the Prospective ProMPT trial

BACKGROUND

The prognostic value of circulating tumor cells (CTCs) in patients with hormone-naïve oligometastatic prostate cancer (HNoMPC) undergoing cytoreductive radical prostatectomy (CRP) is unknown.

OBJECTIVE

To determine the pre- and postoperative prognostic value of CTC enumeration in patients undergoing CRP.

DESIGN, SETTING, AND PARTICIPANTS

Thirty-three patients with HNoMPC from the prospective, single-arm ProMPT trial who underwent CRP between 2014 and 2015 at the Martini-Klinik were evaluated. Follow-up visits for all patients were conducted every 6 mo up to 36 mo after CRP and included serial detection of CTCs in 7.5 ml blood samples using the CellSearch system.

INTERVENTION

CRP.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

CTC enumerations before and after CRP, and their prognostic value on metastatic castration-resistant prostate cancer-free survival and overall survival (OS) were analyzed using Kaplan-Meier plots and univariable Cox-regression analysis.

RESULTS AND LIMITATIONS

Sixteen patients (48.5%) had positive CTCs prior to CRP. A CTC count of ≥2 before or 6 mo after CRP was a prognostic factor for worse oncologic outcome. Compared with other biomarkers (prostate-specific antigen, lactate dehydrogenase, and bone-specific alkaline phosphatase), the prognostic value of CTCs was highest using Harrell's C for OS (0.69), while the highest C-index could be achieved for a combination of conventional markers and CTC count (0.74). After progression to metastatic castration-resistant prostate cancer, CTC enumeration of ≥5 was prognostic for OS. The main limitation is the small sample size.

CONCLUSIONS

CTC enumeration contributes to prognostic information, which might help select HNoMPC patients who might benefit most from CRP.

PATIENT SUMMARY

In this report, we looked at the value of circulating tumor cell (CTC) determination in patients undergoing radical prostatectomy for oligometastatic prostate cancer. We could show that the number of CTCs was a prognostic factor at all analyzed time points and was more closely associated with prognosis than other biomarkers commonly used in daily clinical practice.

The biology and clinical potential of circulating tumor cells

Background

Tumor cells can shed from the tumor, enter the circulation and travel to distant organs, where they can seed metastases. These cells are called circulating tumor cells (CTCs). The ability of CTCs to populate distant tissues and organs has led us to believe they are the primary cause of cancer metastasis. The biological properties and interaction of CTCs with other cell types during intravasation, circulation in the bloodstream, extravasation and colonization are multifaceted and include changes of CTC phenotypes that are regulated by many signaling molecules, including cytokines and chemokines. Considering a sample is readily accessible by a simple blood draw, monitoring CTC levels in the blood has exceptional implications in oncology field. A method called the liquid biopsy allows the extraction of not only CTC, but also CTC products, such as cell free DNA (cfDNA), cell free RNA (cfRNA), microRNA (miRNA) and exosomes.

Conclusions

The clinical utility of CTCs and their products is increasing with advances in liquid biopsy technology. Clinical applications of liquid biopsy to detect CTCs and their products are numerous and could be used for screening of the presence of the cancer in the general population, as well as for prognostic and predictive biomarkers in cancer patients. With the development of better CTC isolation technologies and clinical testing in large prospective trials, increasing clinical utility of CTCs can be expected. The understanding of their biology and interactions with other cell types, particularly with those of the immune system and the rise of immunotherapy also hold great promise for novel therapeutic possibilities.

Circulating Tumor Cells in Prostate Cancer: From Discovery to Clinical Utility

BACKGROUND

Prostate cancer represents the most common non–skin cancer type in men. Unmet needs include understanding prognosis to determine when intervention is needed and what type, prediction to guide the choice of a systemic therapy, and response indicators to determine whether a treatment is working. Over the past decade, the “liquid biopsy,” characterized by the analysis of tumor cells and tumor cell products such as cell-free nucleic acids (DNA, microRNA) or extracellular vesicles circulating in the blood of cancer patients, has received considerable attention.

CONTENT

Among those biomarkers, circulating tumor cells (CTCs) have been most intensively analyzed in prostate cancer. Here we discuss recent studies on the enumeration and characterization of CTCs in peripheral blood and how this information can be used to develop biomarkers for each of these clinical contexts. We focus on clinical applications in men with metastatic castration-resistant prostate cancer, in whom CTCs are more often detected and at higher numbers, and clinical validation for different contexts of use is most mature.

SUMMARY

The overall goal of CTC-based liquid biopsy testing is to better inform medical decision-making so that patient outcomes are improved.

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.

Molecular biomarkers to guide precision medicine in localized prostate cancer

INTRODUCTION

Major advances through tumor profiling technologies, that include next-generation sequencing, epigenetic, proteomic and transcriptomic methods, have been made in primary prostate cancer, providing novel biomarkers that may guide precision medicine in the near future. Areas covered: The authors provided an overview of novel molecular biomarkers in tissue, blood and urine that may be used as clinical tools to assess prognosis, improve selection criteria for active surveillance programs, and detect disease relapse early in localized prostate cancer. Expert commentary: Active surveillance (AS) in localized prostate cancer is an accepted strategy in patients with very low-risk prostate cancer. Many more patients may benefit from watchful waiting, and include patients of higher clinical stage and grade, however selection criteria have to be optimized and early recognition of transformation from localized to lethal disease has to be improved by addition of molecular biomarkers. The role of non-invasive biomarkers is challenging the need for repeat biopsies, commonly performed at 1 and 4 years in men under AS programs.

Clinical applications of the CellSearch platform in cancer patients

The CellSearch® system (CS) enables standardized enrichment and enumeration of circulating tumor cells (CTCs) that are repeatedly assessable via non-invasive "liquid biopsy". While the association of CTCs with poor clinical outcome for cancer patients has clearly been demonstrated in numerous clinical studies, utilizing CTCs for the identification of therapeutic targets, stratification of patients for targeted therapies and uncovering mechanisms of resistance is still under investigation. Here, we comprehensively review the current benefits and drawbacks of clinical CTC analyses for patients with metastatic and non-metastatic tumors. Furthermore, the review focuses on approaches beyond CTC enumeration that aim to uncover therapeutically relevant antigens, genomic aberrations, transcriptional profiles and epigenetic alterations of CTCs at a single cell level. This characterization of CTCs may shed light on the heterogeneity and genomic landscapes of malignant tumors, an understanding of which is highly important for the development of new therapeutic strategies.

An RNA-Based Digital Circulating Tumor Cell Signature Is Predictive of Drug Response and Early Dissemination in Prostate Cancer

Blood-based biomarkers are critical in metastatic prostate cancer, where characteristic bone metastases are not readily sampled, and they may enable risk stratification in localized disease. We established a sensitive and high-throughput strategy for analyzing prostate circulating tumor cells (CTC) using microfluidic cell enrichment followed by digital quantitation of prostate-derived transcripts. In a prospective study of 27 patients with metastatic castration-resistant prostate cancer treated with first-line abiraterone, pretreatment elevation of the digital CTC_M score identifies a high-risk population with poor overall survival (HR = 6.0; P = 0.01) and short radiographic progression-free survival (HR = 3.2; P = 0.046). Expression of HOXB13 in CTCs identifies 6 of 6 patients with ≤12-month survival, with a subset also expressing the ARV7 splice variant. In a second cohort of 34 men with localized prostate cancer, an elevated preoperative CTC_L score predicts microscopic dissemination to seminal vesicles and/or lymph nodes (P < 0.001). Thus, digital quantitation of CTC-specific transcripts enables noninvasive monitoring that may guide treatment selection in both metastatic and localized prostate cancer.Significance: There is an unmet need for biomarkers to guide prostate cancer therapies, for curative treatment of localized cancer and for application of molecularly targeted agents in metastatic disease. Digital quantitation of prostate CTC-derived transcripts in blood specimens is predictive of abiraterone response in metastatic cancer and of early dissemination in localized cancer. Cancer Discov; 8(3); 288-303. ©2018 AACR.See related commentary by Heitzer and Speicher, p. 269This article is highlighted in the In This Issue feature, p. 253.

Multiplex Gene Expression Profiling of In Vivo Isolated Circulating Tumor Cells in High-Risk Prostate Cancer Patients

BACKGROUND

Molecular characterization of circulating tumor cells (CTCs) is important for selecting patients for targeted treatments. We present, for the first time, results on gene expression profiling of CTCs isolated in vivo from high-risk prostate cancer (PCa) patients compared with CTC detected by 3 protein-based assays-CellSearch^®, PSA-EPISPOT, and immunofluorescence of CellCollector^® in vivo-captured CTCs-using the same blood draw.

METHODS

EpCAM-positive CTCs were isolated in vivo using the CellCollector from 108 high-risk PCa patients and 36 healthy volunteers. For 27 patients, samples were available before and after treatment. We developed highly sensitive multiplex RT-qPCR assays for 14 genes (KRT19, EpCAM, CDH1, HMBS, PSCA, ALDH1A1, PROM1, HPRT1, TWIST1, VIM, CDH2, B2M, PLS3, and PSA), including epithelial markers, stem cell markers, and epithelial-to-mesenchymal-transition (EMT) markers.

RESULTS

We observed high heterogeneity in gene expression in the captured CTCs for each patient. At least 1 marker was detected in 74 of 105 patients (70.5%), 2 markers in 45 of 105 (40.9%), and 3 markers in 16 of 105 (15.2%). Epithelial markers were detected in 31 of 105 (29.5%) patients, EMT markers in 46 of 105 (43.8%), and stem cell markers in 15 of 105 (14.3%) patients. EMT-marker positivity was very low before therapy (2 of 27, 7.4%), but it increased after therapy (17 of 27, 63.0%), whereas epithelial markers tended to decrease after therapy (2 of 27, 7.4%) compared with before therapy (13 of 27, 48.1%). At least 2 markers were expressed in 40.9% of patients, whereas the positivity was 19.6% for CellSearch, 38.1% for EPISPOT, and 43.8% for CellCollector-based IF-staining.

CONCLUSIONS

The combination of in vivo CTC isolation with downstream RNA analysis is highly promising as a high-throughput, specific, and ultrasensitive approach for multiplex liquid biopsy-based molecular diagnostics.

Circulating tumor cells in prostate cancer: Precision diagnosis and therapy

The primary cause of tumor-associated mortality in prostate cancer (PCa) remains distant metastasis. The dissemination of tumor cells from the primary tumor to distant sites through the bloodstream cannot be detected early by standard imaging methods. Circulating tumor cells (CTCs) represent an effective prognostic and predictive biomarker, which are able to monitor efficacy of adjuvant therapies, detect early development of metastases, and finally, assess therapeutic responses of advanced disease earlier than traditional diagnostic methods. In addition, since repeated tissue biopsies are invasive, costly and not always feasible, the assessment of tumor characteristics on CTCs, by a peripheral blood sample as a liquid biopsy, represents an attractive opportunity. The implementation of molecular and genomic characterization of CTCs may contribute to improve the treatment selection and thus, to move toward more precise diagnosis and therapy in PCa. The present study summarizes the current advances in CTC enrichment and detection strategies and reviews how CTCs may contribute to significant insights in the metastatic process, as well as how they may be utilized in clinical application in PCa. Although it is proposed that CTCs may offer insights into the prognosis and management of PCa, there are a number of challenges in the study of circulating tumor cells, and their clinical utility remains under investigation.

Biological and Molecular Characterization of Circulating Tumor Cells: A Creative Strategy for Precision Medicine?

Circulating tumor cells (CTCs) are a group of rare cells disseminated from either primary or metastatic tumors into the blood stream. CTCs are considered to be the precursor of cancer metastasis. As a critical component of liquid biopsies, CTCs are a unique tool to understand the formation of metastasis and a valuable source of information on intratumor heterogeneity. Much effort has been invested in technologies for the detection of CTCs because they are rare cells among the vast number of blood cells. Studies in various cancers have repeatedly demonstrated that increased CTC counts prior to or during treatment are significantly associated with poor outcomes. In the new era of precision medicine, the study of CTCs reaches far beyond detection and counting. The rapidly growing field of analytical platforms for rare-cell analysis allows in-depth characterization of CTCs at the bulk cell and single-cell level. Genetic profiling of CTCs may provide an insight into the real-time tumor status, may allow the monitoring and evaluation of treatment response in clinical routine, and may lead to the development of novel therapeutic targets as well.

Circulating tumor cells: clinical validity and utility

Circulating tumor cells (CTCs) are rare tumor cells and have been investigated as diagnostic, prognostic and predictive biomarkers in many types of cancer. Although CTCs are not currently used in clinical practice, CTC studies have accumulated a high level of clinical validity, especially in breast, lung, prostate and colorectal cancers. In this review, we present an overview of the current clinical validity of CTCs in metastatic and non-metastatic disease, and the main concepts and studies investigating the clinical utility of CTCs. In particular, this review will focus on breast, lung, colorectal and prostate cancer. Three major topics concerning the clinical utility of CTC are discussed-(1) treatment based on CTCs used as liquid biopsy, (2) treatment based on CTC count or CTC variations, and (3) treatment based on CTC biomarker expression. A summary of published or ongoing phase II and III trials is also presented.

Circulating tumor cells and circulating tumor DNA: What surgical oncologists need to know?

As a result of recent progress in detection techniques, circulating tumor DNA (ctDNA) and circulating tumor cells (CTC) can now be accurately detected in the blood of most cancer patients. While these new biomarkers can provide a better understanding of key biological mechanisms underlying cancer growth and dissemination, they also open up a wide range of possible clinical applications in medical oncology, radiation oncology and surgical oncology. In this review, we summarize the results obtained with ctDNA and CTC together with their potential future clinical applications in the field of surgical oncology, with particular focus on the perioperative setting of various types of cancer. These applications include, but are not limited to, cancer screening, early diagnosis, prognostic assessment, evaluation and management of preoperative systemic or local therapies, post-surgical detection of minimal residual disease and early detection of cancer relapse.

Improved detection of circulating tumor cells in non-metastatic high-risk prostate cancer patients

The relevance of blood-based assays to monitor minimal residual disease (MRD) in non-metastatic prostate cancer (PCa) remains unclear. Proving that clinically relevant circulating tumor cells (CTCs) can be detected with available technologies could address this. This study aimed to improve CTC detection in non-metastatic PCa patients by combining three independent CTC assays: the CellSearch system, an in vivo CellCollector and the EPISPOT. Peripheral blood samples from high-risk PCa patients were screened for CTCs before and three months after radical prostatectomy (RP). Combining the results of both time points, CTCs were detected in 37%, 54.9% and 58.7% of patients using CellSearch, CellCollector and EPISPOT, respectively. The cumulative positivity rate of the three CTC assays was 81.3% (87/107) with 21.5% (23/107) of patients harboring ≥5 CTCs/7.5 ml blood. Matched pair analysis of 30 blood samples taken before and after surgery indicated a significant decrease in CTCs captured by the CellCollector from 66% before RP to 34% after therapy (p = 0.031). CTC detection by EPISPOT before RP significantly correlated with PSA serum values (p < 0.0001) and clinical tumor stage (p = 0.04), while the other assays showed no significant correlations. In conclusion, CTC-based liquid biopsies have the potential to monitor MRD in patients with non-metastatic prostate cancer.

Dynamics of three-dimensional telomere profiles of circulating tumor cells in patients with high-risk prostate cancer who are undergoing androgen deprivation and radiation therapies

INTRODUCTION

Accurate assessment and monitoring of the therapeutic efficacy of locally advanced prostate cancer remains a major clinical challenge. Contrary to prostate biopsies, circulating tumor cells (CTCs) are a cellular source repeatedly obtainable by blood sampling and could serve as a surrogate marker for treatment efficacy. In this study, we used size-based filtration to isolate and enumerate CTCs from the blood of 20 patients with high-risk (any one of cT3, Gleason 8-10, or prostate-specific antigen>20ng/ml), nonmetastatic, and treatment-naive prostate cancer before and after androgen deprivation therapy (ADT) and radiation therapy (RT).

MATERIALS AND METHODS

We performed 3D telomere-specific quantitative fluorescence in situ hybridization on isolated CTCs to determine 3D telomere profiles for each patient before and throughout the course of both ADT and RT.

RESULTS

Based on the distinct 3D telomere signatures of CTC before treatment, patients were divided into 3 groups. ADT and RT resulted in distinct changes in 3D telomere signatures of CTCs, which were unique for each of the 3 patient groups.

CONCLUSION

The ability of 3D telomere analysis of CTCs to identify disease heterogeneity among a clinically homogeneous group of patients, which reveals differences in therapeutic responses, provides a new opportunity for better treatment monitoring and management of patients with high-risk prostate cancer.

Circulating tumor cell clusters: What we know and what we expect (Review)

The major cause of cancer-associated mortality is tumor metastasis, a disease that is far from understood. Many studies have observed circulating tumor cells (CTCs) in patients' circulation systems, and a few latest investigations showed that CTC clusters have a potentially high capacity of metastasis. The capture and analysis of CTC clusters offer new insights into tumor metastasis and can facilitate the development of cancer treatments. We reviewed the research history of the CTC clusters, as well as the technologies used for detecting and isolating CTC clusters. In addition, we discuss the characteristics of CTC clusters and their roles in tumor dissemination. Clinical relevance of CTC clusters was also implicated in currently limited data. Moving forward, the next frontier in this field is to develop more efficient capture methods and decipher conundrums of characterization of CTC clusters. This will ultimately identify the clinical value of CTC clusters as a biomarker and therapeutic target.

Clinical diagnosis of colorectal cancer using electrospun triple-blend fibrous mat-based capture assay of circulating tumor cells

Conventional in vitro circulating tumor cell (CTC) detection methods are always limited by the blood sample volume because of the extremely low abundance of CTCs among the large number of hematologic cells. The aim of this study was to overcome this limitation by designing and constructing an in vitro CTC capture assay. We blended poly(sulfobetaine methacrylate) (PSBMA) and poly(acrylic acid) (PAA) into nylon-6 through electrospinning to generate a fibrous mat-based capture assay of CTCs. The contents of nylon-6, PSBMA, and PAA in the electrospun triple-blend fibrous mats (ETBFMs) were optimized to avoid degradation and to balance between the non-biofouling behavior and the antibody immobilizing efficiency. In addition, we examined the capture ability of CTCs for clinical diagnoses of colorectal cancer, in comparison with the results identified through pathological analyses of biopsies from colonoscopies. For nine individuals with stage II, III, and IV colorectal cancer, our CTC detection with ETBFMs provided complete positive expression. Two of four individuals were diagnosed to possess stage I colorectal cancer. Two of seven individuals without colorectal tumor, as identified through pathological analyses of biopsies, exhibited positive expression of CTCs. These positive results suggest that such ETBFMs are promising materials for in vitro CTC capture assays.

Clinical Applications of Circulating Tumor Cells and Circulating Tumor DNA as Liquid Biopsy

"Liquid biopsy" focusing on the analysis of circulating tumor cells (CTC) and circulating cell-free tumor DNA (ctDNA) in the blood of patients with cancer has received enormous attention because of its obvious clinical implications for personalized medicine. Analyses of CTCs and ctDNA have paved new diagnostic avenues and are, to date, the cornerstones of liquid biopsy diagnostics. The present review focuses on key areas of clinical applications of CTCs and ctDNA, including detection of cancer, prediction of prognosis in patients with curable disease, monitoring systemic therapies, and stratification of patients based on the detection of therapeutic targets or resistance mechanisms.

SIGNIFICANCE

The application of CTCs and ctDNA for the early detection of cancer is of high public interest, but it faces serious challenges regarding specificity and sensitivity of the current assays. Prediction of prognosis in patients with curable disease can already be achieved in several tumor entities, particularly in breast cancer. Monitoring the success or failure of systemic therapies (i.e., chemotherapy, hormonal therapy, or other targeted therapies) by sequential measurements of CTCs or ctDNA is also feasible. Interventional studies on treatment stratification based on the analysis of CTCs and ctDNA are needed to implement liquid biopsy into personalized medicine. Cancer Discov; 6(5); 479-91. ©2016 AACR.

Diagnostic and Prognostic Value of Circulating Tumor Cells in Head and Neck Squamous Cell Carcinoma: a systematic review and meta-analysis

Several techniques have been developed to detect circulating tumor cells (CTC) in patients with head and neck squamous cell carcinoma (HNSCC), but their diagnostic and prognostic value are not yet fully established. A computerized retrieval of literatures was conducted without time restrictions using the electronic database in December 2014. Diagnostic accuracy variables were pooled and analyzed by the Meta-DiSc software. Engauge Digitizer and Stata software were used for pooled survival analysis. Twenty-two retrieved studies were eligible for systematic review, of which 9 conformed for the diagnostic test meta-analysis and 5 for the prognostic analysis. Subgroup analysis showed 24.6% pooled sensitivity and 100% pooled specificity of detections by using positive selection strategy, which moreover presented low heterogeneity. The presence of CTC was significantly associated with shorter disease free survival (DFS, HR 4.62, 95% CI 2.51-8.52). In conclusion, current evidence identifies the CTC detection assay as an extremely specific, but low sensitive test in HNSCC. Also, the presence of CTC indicates a worse DFS.

Limited prognostic value of preoperative circulating tumor cells for early biochemical recurrence in patients with localized prostate cancer

INTRODUCTION

The presence of circulating tumor cells (CTCs) is an established marker for prognosis in men with castration-resistant prostate cancer. A cutoff of ≥5 CTCs/7.5ml blood in the CellSearch Epithelial Cell Test has been shown to stratify prognostic groups and predict outcome of abiraterone treatment. In contrast, the value of CTC detection in men with localized prostrate cancer before radical prostatectomy (RP) is unknown.

MATERIALS AND METHODS

A total of 152 patients treated with RP between 06/2009 and 09/2009 were included. Peripheral venous blood drawn the day before RP was evaluated for CTCs by the CellSearch system. The detection of CTCs was correlated with prostate-specific antigen (PSA) and the histopathological outcome of the RP specimen. A cutoff of 0 vs. ≥1 CTC/7.5ml blood was defined as the threshold for positive vs. negative CTC status.

RESULTS

Median age was 62 years and median PSA was 6.7ng/dl. Staging revealed 62.5% pT2, 26.3% pT3a, and 11.2% pT3b tumors, and high-grade disease (≥Gleason 4+3) was determined in 25.6% of patients. CTCs were detected in 17 patients (11%) with a median CTC count/7.5ml of 1 (range: 1-clusters with>100 epithelial cells) without significant correlations to PSA levels, pT stage, or Gleason scores. Postoperative pT stage was a significant predictor of biochemical recurrence (BCR) in univariable logistic regression models and as a composite measure together with positive CTC counts (P<0.0001). CTC positivity alone tended to have a higher hazard ratio for BCR, but this was not statistically significant (P = 0.1). After a median follow-up of 48 months, there was no significant difference in BCR-free survival between patients with or without CTCs (P = 0.7).

CONCLUSION

Using the CellSearch system, we infrequently detected CTCs in patients with localized tumors before RP. The detection of CTCs did not correlate significantly with PSA, disease characteristics, or the development of BCR. However, larger cohorts with extended follow-up are needed to validate our findings.

A prospective study of nomogram-based adaptation of prostate radiotherapy target volumes

BACKGROUND

A prospective clinical trial was conducted to evaluate the feasibility of a novel approach to the treatment of patients with high risk prostate cancer (HRPC) through the use of a nomogram to tailor radiotherapy target volumes.

METHODS

Twenty seven subjects with HRPC were treated with a mildly hypofractionated radiotherapy regimen using image-guided IMRT technique between Jun/2013-Jan/2015. A set of validated prognostic factors were inputted into the Memorial-Sloan-Kettering Cancer Center (MSKCC) prostate cancer nomogram to estimate risk of loco-regional spread (LRS). The nomogram risk estimates for extra-capsular extension (ECE), seminal vesicles involvement (SVI), and pelvic lymph nodes involvement (LNI) were used to adapt radiotherapy treatment volumes based on a risk threshold of ≥15 % in all cases. A planning guide was used to delineate target volumes and organs at risk (OAR). Up to three dose levels were administered over 28 fractions; 70Gy for gross disease in the prostate +/- seminal vesicles (2.5Gy/fraction), 61.6Gy for subclinical peri-prostatic disease (2.2Gy/fraction) and 50.4Gy to pelvic nodes (1.8Gy/fraction). Data regarding protocol adherence, nomogram use, radiotherapy dose distribution, and acute toxicity were collected.

RESULTS

Nomogram use 100 % of patients were treated for ECE, 88.9 % for SVI, and 70.4 % for LNI. The three areas at risk of LRS were appropriately treated according to the study protocol in 98.8 % cases. The MSKCC nomogram estimates for LRS differed significantly between the time of recruitment and analysis. Contouring protocol compliance Compliance with the trial contouring protocol for up to seven target volumes was 93.0 % (159/171). Compliance with protocol for small bowel contouring was poor (59.3 %). Dose constraints compliance Compliance with dose constraints for target volumes was 97.4 % (191/196). Compliance with dose constraints for OAR was 88.2 % (285/323). Acute toxicity There were no grade 3 acute toxicities observed. 20/27 (74.1 %) and 6/27 (22.2 %) patients experienced a grade 2 genitourinary and gastrointestinal toxicity respectively.

CONCLUSIONS

We have demonstrated the feasibility of this novel risk-adapted radiation treatment protocol for HRPC. This study has identified key learning points regarding this approach, including the importance of standardization and updating of risk quantification tools, and the utility of an observer to verify their correct use.

TRIAL REGISTRATION

ClincialTrials.gov identifier NCT01418040 . Hunter New England Human Research Ethics Committee (HNEHREC) reference number 12/08/15/4.02.

Feasibility study of a randomized controlled trial comparing docetaxel chemotherapy and androgen deprivation therapy with sequential prostatic biopsies from patients with advanced non-castration-resistant prostate cancer

BACKGROUND AND OBJECTIVE

Sequential tissue biopsies taken during clinical trials of novel systemic anticancer therapies for advanced prostate cancer (PCa) may aid pharmacodynamic evaluation and biomarker discovery. We conducted a single institution phase-II open-labeled randomized study to assess the safety, tolerability, and early efficacy of docetaxel chemotherapy plus androgen deprivation therapy (ADT) vs. ADT alone for patients with advanced non-castration-resistant PCa with sequential prostatic biopsies.

PATIENTS AND METHODS

We randomized 30 patients with newly diagnosed high-grade locally advanced or metastatic (cT3-4/N0-1/M0-1) PCa to receive ADT with (n = 15) or without (n = 15) docetaxel. Transrectal ultrasound-guided prostatic biopsies were taken at randomization and ~22 weeks after treatment initiation. Primary end point: biochemical response rate. Secondary end points: time to progression and tumor profiling.

RESULTS

Both treatments appear to be well tolerated, and there was no difference in mean nadir prostate-specific antigen and time to prostate-specific antigen relapse between treatment arms (P>0.05). No adverse effects of pre- and post-treatment prostatic biopsies were observed. The study was neither designed nor sufficiently powered to demonstrate statistically significant differences in oncological outcomes or safety profiles between the 2 treatment arms.

CONCLUSIONS

Despite the lack of statistical power, our study suggests that docetaxel and ADT in combination may be well tolerated with apparently similar short-term efficacy compared with ADT alone for high-grade locally advanced or metastatic non-castration-resistant PCa, Sequential prostatic biopsies may provide tissue for tumor profiling to yield mechanistic or prognostic insights relating to novel systemic anticancer therapies.

Synergistic action of image-guided radiotherapy and androgen deprivation therapy

The combined use of androgen deprivation therapy (ADT) and image-guided radiotherapy (IGRT) can improve overall survival in aggressive, localized prostate cancer. However, owing to the adverse effects of prolonged ADT, it is imperative to identify the patients who would benefit from this combined-modality therapy relative to the use of IGRT alone. Opportunities exist for more personalized approaches in treating aggressive, locally advanced prostate cancer. Biomarkers--such as disseminated tumour cells, circulating tumour cells, genomic signatures and molecular imaging techniques--could identify the patients who are at greatest risk for systemic metastases and who would benefit from the addition of systemic ADT. By contrast, when biomarkers of systemic disease are not present, treatment could proceed using local IGRT alone. The choice of drug, treatment duration and timing of ADT relative to IGRT could be predicated on these personalized approaches to prostate cancer medicine. These novel treatment intensification and reduction strategies could result in improved prostate-cancer-specific survival and overall survival, without incurring the added expense of metabolic syndrome and other adverse effects of ADT in all patients.

Circulating tumor cells versus objective response assessment predicting survival in metastatic castration-resistant prostate cancer patients treated with docetaxel chemotherapy

PURPOSE

Circulating tumor cell (CTC) counts might display a superior prognostic value for overall survival (OS) compared to objective response criteria (OR) in metastatic castration-resistant prostate cancer (mCRPC) patients.

METHODS

CTCs were detected using the CellSearch™ System out of 122 samples during docetaxel chemotherapy (75 mg/m(2)) at baseline (q0) and after 1 (q1), 4 (q4) and 10 (q10) cycles, in mCRPC patients (n = 33). OR was evaluated by morphologic RECIST and clinical criteria after 4 (q4) and 10 (q10) cycles.

RESULTS

For OS, analyses revealed a significant prognostic value for categorical (<5 vs. ≥5) CTC counts (q0, p = 0.005; q1, p = 0.001; q4, p < 0.001; q10, p = 0.002), RECIST (q4, p < 0.001; q10, p = 0.02) and clinical criteria (q4, p < 0.001; q10, p = 0.02). Concordance of CTC counts with OR revealed a sensitivity of 83.3-87.5 % and a specificity of 68.0-76.5 % with complementary discriminatory power for OS. Comparing CTC counts with concomitant OR at q4 in multivariate analyses, an independent prognostic value for OS was found for CTC counts (HR 3.3; p = 0.02) similar to clinical (HR 4.9; p = 0.02) and radiologic response (HR 3.4; p = 0.051). Comparing the predictive value for death, early post-treatment CTC counts at q1 demonstrated significant accuracy with an area under the curve of 79.5 % (p = 0.004) similar to CTC counts at q4 (76.7 %; p = 0.009). Radiologic and clinical response at q4 displayed accuracy similar to early CTC counts at q1 (72.2 %; p = 0.03 and 75.0 %; p = 0.02) despite low sensitivities.

CONCLUSIONS

CTC counts appear to be an earlier and more sensitive predictor for survival and treatment response than current OR approaches and may provide complementary information toward individualized treatment strategies.

CTC enumeration and characterization: moving toward personalized medicine

The primary cause of tumor-related death in breast cancer (BC) is still represented by distant metastasization. The dissemination of tumor cells from the primary tumor to distant sites through bloodstream cannot be early detected by standard imaging methods. The enumeration of circulating tumor cells (CTCs) represents an effective prognostic and predictive biomarker, which is able to monitor efficacy of adjuvant therapies, detect early development of (micro)metastases and at last, assess therapeutic responses of advanced disease earlier than traditional imaging methods. Moreover, since repeated tissue biopsies are invasive, costly and not always feasible, the assessment of tumor characteristics on CTCs, by a peripheral blood sample as a 'liquid biopsy', represents an attractive opportunity. The implementation of molecular and genomic characterization of CTCs could contribute to improve the treatment selection and thus, to move toward more personalized treatments. This review describes the current state of the art on CTC detection strategies, the evidence to demonstrate their clinical validity, and their potential impact for both future clinical trial design and, decision-making process in our daily practice.