Validation of Cell-Free RNA and Circulating Tumor Cells for Molecular Marker Analysis in Metastatic Prostate Cancer

Combined microfluidic enrichment and staining workflow for single-cell analysis of circulating tumor cells in metastatic prostate cancer patients

Circulating tumor cells (CTCs) are precursors of cancer in the blood and provide an attractive source for dynamic monitoring of disease progression and tumor heterogeneity. However, the scarcity of CTCs in the bloodstream has limited their use in clinical practice. In this study, we present a workflow for easy detection of CTCs by cytokeratin staining using the FDA-cleared Parsortix device for size-based microfluidic enrichment. To minimize sample handling, the isolated cells are stained inside the separation cassette and harvested for subsequent single cell isolation and whole genome copy-number analysis. We validated the workflow on a panel of four prostate cancer cell lines spiked into healthy donor blood collected in CellRescue or EDTA tubes, resulting in mean recoveries of 42% (16-69%). Furthermore, we evaluated the clinical utility in a cohort of 12 metastatic prostate cancer patients and found CTCs in 67% of patients ranging from 0 to 1172 CTCs in 10 mL blood. Additionally, we isolated single patient-derived CTCs and identified genomic aberrations associated with treatment response and clinical outcome. Thus, this workflow provides a readily scalable strategy for analysis of single CTCs, applicable for use in monitoring studies to identify genomic variations important for guiding clinical therapy decision.

Exploring the Role of Circulating Cell-Free RNA in the Development of Colorectal Cancer

Circulating tumor RNA (ctRNA) has recently emerged as a novel and attractive liquid biomarker. CtRNA is capable of providing important information about the expression of a variety of target genes noninvasively, without the need for biopsies, through the use of circulating RNA sequencing. The overexpression of cancer-specific transcripts increases the tumor-derived RNA signal, which overcomes limitations due to low quantities of circulating tumor DNA (ctDNA). The purpose of this work is to present an up-to-date review of current knowledge regarding ctRNAs and their status as biomarkers to address the diagnosis, prognosis, prediction, and drug resistance of colorectal cancer. The final section of the article discusses the practical aspects involved in analyzing plasma ctRNA, including storage and isolation, detection technologies, and their limitations in clinical applications.

Long-Term Treatment with Simvastatin Leads to Reduced Migration Capacity of Prostate Cancer Cells

Statins have been shown to improve survival of metastatic prostate cancer (mPCa). Nevertheless, their therapeutic use is still under debate. In the present study, we investigated the short-term effects of three different statins (simvastatin, atorvastatin and rosuvastatin) in various PCa cell lines mimicking androgen-sensitive and -insensitive PCa. Moreover, we generated three new PCa cell lines (LNCaPsim, ABLsim, PC-3sim) that were cultured with simvastatin over several months. Our data showed that the three statins expressed highly diverse short-term effects, with the strongest growth-inhibitory effect from simvastatin in PC-3 cells and almost no effect from rosuvastatin in any of the cell lines. Long-term treatment with simvastatin resulted in a loss of response to statins in all three cell lines, which was associated with an upregulation of cholesterol and fatty acid pathways as revealed through RNA sequencing. Despite that, long-term treated cells exhibited diminished spheroid growth and significantly reduced migration capacity per se and to differentiated osteoclasts. These findings were strengthened by reduced expression of genes annotated to cell adhesion and migration after long-term simvastatin treatment. Notably, mPCa patients taking statins were found to have lower numbers of circulating tumor cells in their blood with reduced levels of PSA and alkaline phosphatase. Our data suggest that long-term usage of simvastatin hampers the metastatic potential of PCa cells and may therefore be a potential therapeutic drug for mPCa.

The Prognostic Value of Liquid Biopsies for Benefit of Salvage Radiotherapy in Relapsed Oligometastatic Prostate Cancer

Simple Summary

Around 30% of patients with oligometastatic prostate cancer relapse will benefit from local PET/CT-guided ablative radiotherapy (RT) with improved progression-free and ADT (Androgene Deprivation Therapy)-free survivals. Therefore, there is an urgent need for predictive testing for therapeutic benefits prior to initiation. Various tests have already been established on tumor specimens for the prediction of prostate cancer’s behavior or therapy outcome. However, in imaging-proven relapse tumor tissue from the local recurrence or metastases is often not available. Hence, there is a need for a liquid biopsy-based testing. We aimed to assess the prognostic value of CTCs- associated mRNA and blood-derived RNA for the benefit of PSMA PET-guided salvage RT in oligometastatic prostate cancer relapses. Significant correlations were found between the relative transcript levels of several investigated genes and clinicopathological parameters. Furthermore, distinct “transcriptional signatures” were found in patients with temporary and long-term benefits from RT.

Abstract

To assess the prognostic value of “liquid biopsies” for the benefit of salvage RT in oligometastatic prostate cancer relapse, we enrolled 44 patients in the study between the years 2016 and 2020. All the patients were diagnosed as having an oligometastatic prostate cancer relapse on prostate-specific membrane antigen (PSMA)-targeted PET-CT and underwent irradiation at the Department of Radiotherapy at the Hannover Medical School. Tumor cells and total RNA, enriched from the liquid biopsies of patients, were processed for the subsequent quantification analysis of relative transcript levels in real-time PCR. In total, 54 gene transcripts known or suggested to be associated with prostate cancer or treatment outcome were prioritized for analysis. We found significant correlations between the relative transcript levels of several investigated genes and the Gleason score, PSA (prostate-specific antigen) value, or UICC stage (tumor node metastasis -TNM classification of malignant tumors from Union for International Cancer Control). Furthermore, a significant association of MTCO2, FOXM1, SREBF1, HOXB7, FDXR, and MTRNR transcript profiles was found with a temporary and/or long-term benefit from RT. Further studies on larger patients cohorts are necessary to prove our preliminary findings for establishing liquid biopsy tests as a predictive examination method prior to salvage RT.

A Systematic Review of Circulating Tumor Cells Clinical Application in Prostate Cancer Diagnosis

Simple Summary

Cell-dependent and cell-independent information drawn from the blood stream were merged into the attractive term “liquid biopsy” and tentatively applied to most segments of cancer management: detection, risk-stratification, personalization of care and follow-up. However, the robust science behind liquid biopsies has not been widely used, thereby remaining a latent and possibly undervalued instrument. Here, we conducted a systematic review of CTCs in prostate cancer management to summarize their use in clinical practice.

Abstract

The purpose of the review is to summarize the recent data on circulating tumor cells (CTC) use in clinical practice. We performed a systematic literature search using two databases (Medline and Scopus) over the past five years and the following terms: (CTC OR “circulating tumor cells” OR “liquid biopsy”) AND prostate. The primary outcome was CTC predictive value for prostate cancer (PC) progression and survival. The secondary outcomes were the CTC predictive value for therapy response and the results of CTC detection depending on the assessment method. In metastatic PC, the CTC count showed itself to be a prognostic marker in terms of clinically important features, namely survival rates and response to treatment. CTC concentration was significantly associated with the overall survival and progression-free survival rates. A strong association between the overall survival or progression-free survival rate and CTC concentration could be observed. Variant-7 androgen receptors-positive (AR-V7-positive) patients showed a poor response to androgen receptor signaling (ARS) inhibitors, but this did not compromise their response to taxanes. In localized PC, only positive Cluster of Differentiantion 82 protein (CD82+) correlated with a higher survival rate. CTC count and AR-V7 expression showed itself to be a valuable biomarker for survival in metastatic PC and response to ARS-inhibitors. CTC diagnostic performance for localized PC or for screening and early detection is not high enough to show additional value over the other biomarkers.

Clinical Applications of Liquid Biopsy in Prostate Cancer: From Screening to Predictive Biomarker

Prostate cancer (PC) remains the most common malignancy and the second most common cause of cancer death in men. As a result of highly variable biological behavior and development of resistance to available agents under therapeutic pressure, optimal management is often unclear. Traditional surgical biopsies, even when augmented by genomic studies, may fail to provide adequate guidance for clinical decisions as these can only provide a snapshot of a dynamic process. Additionally, surgical biopsies are cumbersome to perform repeatedly and often involve risk. Liquid biopsies (LB) are defined as the analysis of either corpuscular (circulating tumor cells, extracellular vesicles) or molecular (circulating DNA or RNA) tumor-derived material. LB could more precisely identify clinically relevant alterations that characterize the metastatic potential of tumors, predict response to specific treatments or actively monitor for the emergence of resistance. These tests can potentially be repeated as often as deemed necessary and can detect real-time response to treatment with minimal inconvenience to the patient. In the current review, we consider common clinical scenarios to describe available LB assays in PC as a platform to explore existing evidence for their use in guiding decision making and to discuss current limitations to their adoption in the clinic.