The Detection of Androgen Receptor Splice Variant 7 in Plasma-derived Exosomal RNA Strongly Predicts Resistance to Hormonal Therapy in Metastatic Prostate Cancer Patients
TL;DR: This study demonstrates that plasma-derived exosomal RNA is a reliable source of AR-V7 that can be detected sensitively by ddPCR assay and shows that resistance to hormonal therapy may be predicted by AR-v7, making it a clinically relevant biomarker.
About: This article is published in European Urology.The article was published on 2017-04-01. It has received 209 citations till now. The article focuses on the topics: Prostate cancer & Hormonal therapy.
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TL;DR: A review of the biophysical properties and physiological functions of extracellular vesicles, particularly their pro-metastatic effects, and highlight the utility of EVs for the development of cancer diagnostics and therapeutics can be found in this paper.
Abstract: The sustained growth, invasion, and metastasis of cancer cells depend upon bidirectional cell-cell communication within complex tissue environments. Such communication predominantly involves the secretion of soluble factors by cancer cells and/or stromal cells within the tumour microenvironment (TME), although these cell types have also been shown to export membrane-encapsulated particles containing regulatory molecules that contribute to cell-cell communication. These particles are known as extracellular vesicles (EVs) and include species of exosomes and shed microvesicles. EVs carry molecules such as oncoproteins and oncopeptides, RNA species (for example, microRNAs, mRNAs, and long non-coding RNAs), lipids, and DNA fragments from donor to recipient cells, initiating profound phenotypic changes in the TME. Emerging evidence suggests that EVs have crucial roles in cancer development, including pre-metastatic niche formation and metastasis. Cancer cells are now recognized to secrete more EVs than their nonmalignant counterparts, and these particles can be isolated from bodily fluids. Thus, EVs have strong potential as blood-based or urine-based biomarkers for the diagnosis, prognostication, and surveillance of cancer. In this Review, we discuss the biophysical properties and physiological functions of EVs, particularly their pro-metastatic effects, and highlight the utility of EVs for the development of cancer diagnostics and therapeutics.
925 citations
University of Bern1, Institute of Cancer Research2, Oregon Health & Science University3, Cornell University4, Princess Margaret Cancer Centre5, Yonsei University6, University of Salford7, University of Copenhagen8, Monash University9, University of São Paulo10, Columbia University11, The Royal Marsden NHS Foundation Trust12, University of Texas MD Anderson Cancer Center13, University of California, Davis14, University of Bologna15, University of California, San Francisco16, University of Paris-Sud17, University of British Columbia18, Duke University19, University of Cologne20, Fred Hutchinson Cancer Research Center21, University of Birmingham22, Memorial Sloan Kettering Cancer Center23, University of Tampere24, American University of Beirut25, Medical University of Vienna26, Vanderbilt University27, Tata Memorial Hospital28, Icahn School of Medicine at Mount Sinai29, Ghent University30, University of Washington31, Université de Montréal32, Tulane University33, Tel Aviv University34, Harvard University35, Prostate Cancer Foundation36, Toho University37, University College London38, University of Toronto39, Université catholique de Louvain40, University of Milan41, University of Ulm42
TL;DR: The presented expert voting results can be used for support in areas of management of men with APC where there is no high-level evidence, but individualised treatment decisions should as always be based on all of the data available.
539 citations
TL;DR: Improved disease management will also benefit from artificial intelligence-based expert decision support systems for proper standard of care, prognostic determinant biomarkers to minimize overtreatment of localized disease, and new standards of care accelerated by next-generation adaptive clinical trials.
Abstract: Despite the high long-term survival in localized prostate cancer, metastatic prostate cancer remains largely incurable even after intensive multimodal therapy The lethality of advanced disease is driven by the lack of therapeutic regimens capable of generating durable responses in the setting of extreme tumor heterogeneity on the genetic and cell biological levels Here, we review available prostate cancer model systems, the prostate cancer genome atlas, cellular and functional heterogeneity in the tumor microenvironment, tumor-intrinsic and tumor-extrinsic mechanisms underlying therapeutic resistance, and technological advances focused on disease detection and management These advances, along with an improved understanding of the adaptive responses to conventional cancer therapies, anti-androgen therapy, and immunotherapy, are catalyzing development of more effective therapeutic strategies for advanced disease In particular, knowledge of the heterotypic interactions between and coevolution of cancer and host cells in the tumor microenvironment has illuminated novel therapeutic combinations with a strong potential for more durable therapeutic responses and eventual cures for advanced disease Improved disease management will also benefit from artificial intelligence-based expert decision support systems for proper standard of care, prognostic determinant biomarkers to minimize overtreatment of localized disease, and new standards of care accelerated by next-generation adaptive clinical trials
377 citations
TL;DR: In this review, an in-depth analysis of the most innovative advances in basic and applied cancer research is provided.
Abstract: Every year, cancer is responsible for millions of deaths worldwide and, even though much progress has been achieved in medicine, there are still many issues that must be addressed in order to improve cancer therapy. For this reason, oncological research is putting a lot of effort towards finding new and efficient therapies which can alleviate critical side effects caused by conventional treatments. Different technologies are currently under evaluation in clinical trials or have been already introduced into clinical practice. While nanomedicine is contributing to the development of biocompatible materials both for diagnostic and therapeutic purposes, bioengineering of extracellular vesicles and cells derived from patients has allowed designing ad hoc systems and univocal targeting strategies. In this review, we will provide an in-depth analysis of the most innovative advances in basic and applied cancer research.
372 citations
Cites background from "The Detection of Androgen Receptor ..."
...Similarly, exosomal AR-V7 mRNA has been used as a prognostic marker of resistance to hormonal therapy in metastatic prostate cancer patients [71]....
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TL;DR: ExoRBase will aid researchers in identifying molecular signatures in blood exosomes and will trigger new exosomal biomarker discovery and functional implication for human diseases.
Abstract: Exosomes, which are nanosized endocytic vesicles that are secreted by most cells, contain an abundant cargo of different RNA species that can modulate the behavior of recipient cells and may be used as circulating biomarkers for diseases. Here, we develop a web-accessible database (http://www.exoRBase.org), exoRBase, which is a repository of circular RNA (circRNA), long non-coding RNA (lncRNA) and messenger RNA (mRNA) derived from RNA-seq data analyses of human blood exosomes. Experimental validations from the published literature are also included. exoRBase features the integration and visualization of RNA expression profiles based on normalized RNA-seq data spanning both normal individuals and patients with different diseases. exoRBase aims to collect and characterize all long RNA species in human blood exosomes. The first release of exoRBase contains 58 330 circRNAs, 15 501 lncRNAs and 18 333 mRNAs. The annotation, expression level and possible original tissues are provided. exoRBase will aid researchers in identifying molecular signatures in blood exosomes and will trigger new exosomal biomarker discovery and functional implication for human diseases.
371 citations
Cites background from "The Detection of Androgen Receptor ..."
...For instance, androgen receptor splice variant 7 (AR-V7) is detectable in plasma-derived exosomal RNA of patients with castration-resistant prostate cancer (CRPC) and may be a predictive biomarker of resistance to hormonal therapy in CRPC (4)....
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References
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TL;DR: In this article, the androgen-receptor splice variant 7 (AR-V7) was found to be associated with resistance to enzalutamide and abiraterone.
Abstract: Background The androgen-receptor isoform encoded by splice variant 7 lacks the ligand-binding domain, which is the target of enzalutamide and abiraterone, but remains constitutively active as a transcription factor. We hypothesized that detection of androgen-receptor splice variant 7 messenger RNA (AR-V7) in circulating tumor cells from men with advanced prostate cancer would be associated with resistance to enzalutamide and abiraterone. Methods We used a quantitative reverse-transcriptase–polymerase-chain-reaction assay to evaluate AR-V7 in circulating tumor cells from prospectively enrolled patients with metastatic castration-resistant prostate cancer who were initiating treatment with either enzalutamide or abiraterone. We examined associations between AR-V7 status (positive vs. negative) and prostate-specific antigen (PSA) response rates (the primary end point), freedom from PSA progression (PSA progression–free survival), clinical or radiographic progression–free survival, and overall survival. Resul...
2,221 citations
"The Detection of Androgen Receptor ..." refers background or methods or result in this paper
...Antonarakis et al [1] found in circulating tumor cells (CTCs) that one splicing variant, androgen receptor splice variant 7 (AR-V7), is associated with resistance to enzalutamide and abiraterone....
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...Although in previous studies [1,18] AR-V7 levels increased over time, in our study only four of seven samples had increasing AR-V7 copies/ml....
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...In prostate cancer the only predictive biomarkers of resistance to therapy are the androgen receptor (AR) splice variants and DNA-repair deficiency, relative to hormonal therapy (HT) and poly(adenosine diphosphate-ribose) polymerase inhibitors, respectively [1,2]....
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...The comparison of CTCs [1] versus plasmaderived exosomes as a source of RNA (present study) demonstrates that CTC AR-V7 patients have a median OS of 8 mo versus not reached for AR-V7 patients [1], a result similar to the present study (8 mo vs not reached, respectively, AR-V7 vs AR-V7 patients)....
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...Several reports demonstrated and validated its role not only in vitro, but also in vivo [1,8,16,17]....
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TL;DR: Treatment with the PARP inhibitor olaparib in patients whose prostate cancers were no longer responding to standard treatments and who had defects in DNA-repair genes led to a high response rate.
Abstract: BackgroundProstate cancer is a heterogeneous disease, but current treatments are not based on molecular stratification. We hypothesized that metastatic, castration-resistant prostate cancers with DNA-repair defects would respond to poly(adenosine diphosphate [ADP]–ribose) polymerase (PARP) inhibition with olaparib. MethodsWe conducted a phase 2 trial in which patients with metastatic, castration-resistant prostate cancer were treated with olaparib tablets at a dose of 400 mg twice a day. The primary end point was the response rate, defined either as an objective response according to Response Evaluation Criteria in Solid Tumors, version 1.1, or as a reduction of at least 50% in the prostate-specific antigen level or a confirmed reduction in the circulating tumor-cell count from 5 or more cells per 7.5 ml of blood to less than 5 cells per 7.5 ml. Targeted next-generation sequencing, exome and transcriptome analysis, and digital polymerase-chain-reaction testing were performed on samples from mandated tumor...
1,694 citations
"The Detection of Androgen Receptor ..." refers background in this paper
...In prostate cancer the only predictive biomarkers of resistance to therapy are the androgen receptor (AR) splice variants and DNA-repair deficiency, relative to hormonal therapy (HT) and poly(adenosine diphosphate-ribose) polymerase inhibitors, respectively [1,2]....
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TL;DR: Circulating exosomes can be used as liquid biopsies and noninvasive biomarkers for early detection, diagnosis, and treatment of cancer patients and emerging evidence suggests that they play a role in facilitating tumorigenesis by regulating angiogenesis, immunity, and metastasis.
Abstract: Humans circulate quadrillions of exosomes at all times. Exosomes are a class of extracellular vesicles released by all cells, with a size range of 40-150 nm and a lipid bilayer membrane. Exosomes contain DNA, RNA, and proteins. Exosomes likely remove excess and/or unnecessary constituents from the cells, functioning like garbage bags, although their precise physiological role remains unknown. Additionally, exosomes may mediate specific cell-to-cell communication and activate signaling pathways in cells they fuse or interact with. Exosomes are detected in the tumor microenvironment, and emerging evidence suggests that they play a role in facilitating tumorigenesis by regulating angiogenesis, immunity, and metastasis. Circulating exosomes can be used as liquid biopsies and noninvasive biomarkers for early detection, diagnosis, and treatment of cancer patients.
1,244 citations
TL;DR: Novel forms of AR alteration that are prevalent in HRPC are reported, suggesting a novel mechanism for the development of HRPC that warrants further investigation and may be explored as potential biomarkers and therapeutic targets for advanced PCa.
Abstract: Suppression of androgen production and function provides palliation but not cure in men with prostate cancer (PCa). Therapeutic failure and progression to hormone-refractory PCa (HRPC) are often accompanied by molecular alterations involving the androgen receptor (AR). In this study, we report novel forms of AR alteration that are prevalent in HRPC. Through in silico sequence analysis and subsequent experimental validation studies, we uncovered seven AR variant transcripts lacking the reading frames for the ligand-binding domain due to splicing of "intronic" cryptic exons to the upstream exons encoding the AR DNA-binding domain. We focused on the two most abundantly expressed variants, AR-V1 and AR-V7, for more detailed analysis. AR-V1 and AR-V7 mRNA showed an average 20-fold higher expression in HRPC (n = 25) when compared with hormone-naive PCa (n = 82; P < 0.0001). Among the hormone-naive PCa, higher expression of AR-V7 predicted biochemical recurrence following surgical treatment (P = 0.012). Polyclonal antibodies specific to AR-V7 detected the AR-V7 protein frequently in HRPC specimens but rarely in hormone-naive PCa specimens. AR-V7 was localized in the nuclei of cultured PCa cells under androgen-depleted conditions, and constitutively active in driving the expression of canonical androgen-responsive genes, as revealed by both AR reporter assays and expression microarray analysis. These results suggest a novel mechanism for the development of HRPC that warrants further investigation. In addition, as expression markers for lethal PCa, these novel AR variants may be explored as potential biomarkers and therapeutic targets for advanced PCa.
1,028 citations
"The Detection of Androgen Receptor ..." refers background in this paper
...Therefore, LBD deletion results in loss of the antiandrogen binding site and constitutive activation of AR-V7 [6]....
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...The LBD is responsible for androgen-dependent receptor activity and the target of flutamide, bicalutamide, and enzalutamide [5,6]....
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TL;DR: CTC nuclear expression of AR-V7 protein in men with mCRPC is validated as a treatment-specific biomarker that is associated with superior survival on taxane therapy over ARS-directed therapy in a clinical practice setting.
Abstract: Importance A critical decision in the management of metastatic castration-resistant prostate cancer (mCRPC) is when to administer an androgen receptor signaling (ARS) inhibitor or a taxane. Objective To determine if pretherapy nuclear androgen-receptor splice variant 7 (AR-V7) protein expression and localization on circulating tumor cells (CTCs) is a treatment-specific marker for response and outcomes between ARS inhibitors and taxanes. Design, Setting, and Participants For this cross-sectional cohort study at Memorial Sloan Kettering Cancer Center, 265 men with progressive mCRPC undergoing a change in treatment were considered; 86 were excluded because they were not initiating ARS or taxane therapy; and 18 were excluded for processing time constraints, leaving 161 patients for analysis. Between December 2012 and March 2015, blood was collected and processed from patients with progressive mCRPC immediately prior to new line of systemic therapy. Patients were followed up to 3 years. Main Outcomes and Measures Prostate-specific antigen (PSA) response, time receiving therapy, radiographic progression-free survival (rPFS), and overall survival (OS). Results Overall, of 193 prospectively collected blood samples from 161 men with mCRPC, 191 were evaluable (128 pre-ARS inhibitor and 63 pretaxane). AR-V7–positive CTCs were found in 34 samples (18%), including 3% of first-line, 18% of second-line, and 31% of third- or greater line samples. Patients whose samples had AR-V7–positive CTCs before ARS inhibition had resistant posttherapy PSA changes (PTPC), shorter rPFS, shorter time on therapy, and shorter OS than those without AR-V7–positive CTCs. Overall, resistant PTPC were seen in 65 of 112 samples (58%) without detectable AR-V7–positive CTCs prior to ARS inhibition. There were statistically significant differences in OS but not in PTPC, time on therapy, or rPFS for patients with or without pretherapy AR-V7–positive CTCs treated with a taxane. A multivariable model adjusting for baseline factors associated with survival showed superior OS with taxanes relative to ARS inhibitors when AR-V7–positive CTCs were detected pretherapy (hazard ratio, 0.24; 95% CI, 0.10-0.57; P = .035). Conclusions and Relevance The results validate CTC nuclear expression of AR-V7 protein in men with mCRPC as a treatment-specific biomarker that is associated with superior survival on taxane therapy over ARS-directed therapy in a clinical practice setting. Continued examination of this biomarker in prospective studies will further aid clinical utility.
531 citations
"The Detection of Androgen Receptor ..." refers background or result in this paper
...In a recent study on AR-V7 analysis on CTCs, it was shown that the incidence and amount of AR-V7 increase by line of therapy, reconfirming the role of AR-V7 as an acquired mechanism of resistance to systemic therapy [18]....
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...Although in previous studies [1,18] AR-V7 levels increased over time, in our study only four of seven samples had increasing AR-V7 copies/ml....
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