Consensus Statement on Circulating Biomarkers for Advanced Prostate Cancer

Circulating Tumor Cells: Origin, Role, Current Applications, and Future Perspectives for Personalized Medicine

Circulating tumor cells (CTCs) currently represent a revolutionary tool offering unique insights for the evaluation of cancer progression, metastasis, and response to therapies. Indeed, CTCs, upon detachment from primary tumors, enter the bloodstream and acquire a great potential for their use for personalized cancer management. In this review, we describe the current understanding of and advances in the clinical employment of CTCs. Although considered rare and fleeting, CTCs are now recognized as key players favoring the development of cancer metastasis and disease recurrence, particularly in malignant melanoma, lung, breast, and colorectal cancer patients. To date, the advancements in technology and the development of several successful approaches, also including immunomagnetic enrichment allow for a reliable and reproducible detection and characterization of CTCs. Those innovative methodologies improved the isolation, quantification, and characterization of CTCs from the blood of cancer patients, providing extremely useful evidence and new insights into the nature of the tumor, its epithelial/mesenchymal profile, and its potential resistance to therapy. In fact, in addition to their prognostic and predictive value, CTCs could serve as a valuable instrument for real-time monitoring of treatment response and disease recurrence, facilitating timely interventions and thus improving patient outcomes. However, despite their potential, several challenges hinder the widespread clinical utility of CTCs: (i) CTCs' rarity and heterogeneity pose technical limitations in isolation and characterization, as well as significant hurdles in their clinical implementation; (ii) it is mandatory to standardize CTC detection methods, optimize the sample processing techniques, and integrate them with existing diagnostic modalities; and (iii) the need for the development of new techniques, such as single-cell analysis platforms, to enhance the sensitivity and specificity of CTC detection, thereby facilitating their integration into routine clinical practice. In conclusion, CTCs represent a potential extraordinary tool in cancer diagnostics and therapeutics, offering unprecedented opportunities for personalized medicine and precision oncology. Moreover, their ability to provide real-time insights into tumor biology, treatment response, and disease progression underlines a great potential for their clinical application to improve patients' outcomes and advance our understanding of cancer biology.

Serum Calcium Level at Diagnosis Can Predict Lethal Prostate Cancer Relapse

Background/Objectives: The most important prognostic factors in curatively treated prostate cancer are T and N stage, histology, grade group and initial PSA. A recent study found that men with blood calcium levels at the high end of the normal range are over two-and-a-half times more likely to develop fatal prostate cancer than those with lower calcium levels. However, there is limited evidence regarding the prognostic value of calcium levels at the time of prostate cancer diagnosis. We aimed to determine whether a calcium level in the upper range of normal values has any prognostic value in curatively treated prostate cancer. Methods: We conducted a retrospective analysis of 84 consecutive patients with prostate cancer who underwent curative-intent radiotherapy-either as primary treatment or adjuvant therapy-using external beam radiotherapy with or without brachytherapy. We analyzed all pertinent prognostic factors that could potentially impact disease-free survival. Results: The study revealed that calcium levels at diagnosis significantly predict disease-free survival, whereas the initial PSA level did not hold prognostic significance-likely due to interference from benign prostatic hyperplasia. Conclusions: If our findings are validated, calcium levels at the time of prostate cancer diagnosis could be incorporated into future predictive and prognostic models.

Prognostic impact of serum testosterone in metastatic hormone-naive prostate cancer: a systematic review and meta-analysis

PURPOSE OF REVIEW

In daily practice, there is an unmet medical need for biomarkers that facilitate therapeutic decision-making in the metastatic hormone sensitive prostate cancer (mHSPC) scenario. Although recent studies have highlighted the potential of testosterone as a prognostic and predictive marker in prostate cancer, the evidence is controversial. The objective of this review was to summarize and analyze the scientific evidence regarding the prognostic role of basal testosterone levels in patients with mHSPC.

METHODS

A systematic review was performed. Three authors selected the articles from Web of Science, PubMed, Scopus, and Cochrane Library electronic databases. Risk of bias was assessed by the Newcastle Ottawa Scale.

RECENT FINDINGS

Most of the selected articles suggest that low testosterone levels before starting hormonal blockade imply a worse prognosis for patients with mHSPC. However, the quality of the evidence is poor, the studies are heterogeneous, and it is not possible to meta-analyze most of the published results.

SUMMARY

Testosterone is an accessible and affordable biomarker. If it were correctly demonstrated that it harbors a prognostic and/or predictive role in the mHSPC setting, it could represent an advance in decision-making in these patients. Well designed prospective studies are needed to correctly answer this question.

Potential of Personalized Dendritic Cell-Based Immunohybridoma Vaccines to Treat Prostate Cancer

Prostate cancer (PCa) is the most commonly diagnosed cancer and the second most common cause of death due to cancer. About 30% of patients with PCa who have been castrated develop a castration-resistant form of the disease (CRPC), which is incurable. In the last decade, new treatments that control the disease have emerged, slowing progression and spread and prolonging survival while maintaining the quality of life. These include immunotherapies; however, we do not yet know the optimal combination and sequence of these therapies with the standard ones. All therapies are not always suitable for every patient due to co-morbidities or adverse effects of therapies or both, so there is an urgent need for further work on new therapeutic options. Advances in cancer immunotherapy with an immune checkpoint inhibition mechanism (e.g., ipilimumab, an anti-CTLA-4 inhibitor) have not shown a survival benefit in patients with CRPC. Other immunological approaches have also not given clear results, which has indirectly prevented breakthrough for this type of therapeutic strategy into clinical use. Currently, the only approved form of immunotherapy for patients with CRPC is a cell-based medicine, but it is only available to patients in some parts of the world. Based on what was gained from recently completed clinical research on immunotherapy with dendritic cell-based immunohybridomas, the aHyC dendritic cell vaccine for patients with CRPC, we highlight the current status and possible alternatives that should be considered in the future.

Detection and Molecular Characterization of Circulating Tumour Cells: Challenges for the Clinical Setting

Over the last decade, liquid biopsy has gained much attention as a powerful tool in personalized medicine since it enables monitoring cancer evolution and follow-up of cancer patients in real time. Through minimally invasive procedures, liquid biopsy provides important information through the analysis of circulating tumour cells (CTCs) and circulating tumour-derived material, such as circulating tumour DNA (ctDNA), circulating miRNAs (cfmiRNAs) and extracellular vehicles (EVs). CTC analysis has already had an important impact on the prognosis, detection of minimal residual disease (MRD), treatment selection and monitoring of cancer patients. Numerous clinical trials nowadays include a liquid biopsy arm. CTC analysis is now an exponentially expanding field in almost all types of solid cancers. Functional studies, mainly based on CTC-derived cell-lines and CTC-derived explants (CDx), provide important insights into the metastatic process. The purpose of this review is to summarize the latest findings on the clinical significance of CTCs for the management of cancer patients, covering the last four years. This review focuses on providing a comprehensive overview of CTC analysis in breast, prostate and non-small-cell lung cancer. The unique potential of CTC single-cell analysis for understanding metastasis biology, and the importance of quality control and standardization of methodologies used in this field, is also discussed.

Diagnostic value of liquid biopsy in the era of precision medicine: 10 years of clinical evidence in cancer

Liquid biopsy is a diagnostic repeatable test, which in last years has emerged as a powerful tool for profiling cancer genomes in real-time with minimal invasiveness and tailoring oncological decision-making. It analyzes different blood-circulating biomarkers and circulating tumor DNA (ctDNA) is the preferred one. Nevertheless, tissue biopsy remains the gold standard for molecular evaluation of solid tumors whereas liquid biopsy is a complementary tool in many different clinical settings, such as treatment selection, monitoring treatment response, cancer clonal evolution, prognostic evaluation, as well as the detection of early disease and minimal residual disease (MRD). A wide number of technologies have been developed with the aim of increasing their sensitivity and specificity with acceptable costs. Moreover, several preclinical and clinical studies have been conducted to better understand liquid biopsy clinical utility. Anyway, several issues are still a limitation of its use such as false positive and negative results, results interpretation, and standardization of the panel tests. Although there has been rapid development of the research in these fields and recent advances in the clinical setting, many clinical trials and studies are still needed to make liquid biopsy an instrument of clinical routine. This review provides an overview of the current and future clinical applications and opening questions of liquid biopsy in different oncological settings, with particular attention to ctDNA liquid biopsy.

Radical Prostatectomy without Prior Biopsy in Patients with High Suspicion of Prostate Cancer Based on Multiparametric Magnetic Resonance Imaging and Prostate-Specific Membrane Antigen Positron Emission Tomography: A Prospective Cohort Study

Modern risk stratification of prostate cancer (PCa) allows for prediction of advanced disease with a high level of certainty. We aimed to evaluate a prospective series of patients undergoing radical prostatectomy without prior biopsy based solely on clinical criteria and imaging results. The patients were divided into three groups. Group 1 included 27 patients with: (i) suspicious digital rectal examination, (ii) PSA ≥ 10 ng/mL, (iii) PI-RADS 4/5 on mpMRI, and (iv) high suspicion of PCa on PSMA-PET. Group 2 included six patients who fulfilled criteria i, ii, and iii but did not undergo PSMA-PET imaging. Group 3 included 17 patients with at least one clinical (i or ii) and one imaging (iii or iv) criterion. All of the patients were diagnosed with PCa. Comparison of Group 1 and 2 versus Group 3 showed a significantly higher ratio of locally advanced PCa for Groups 1 and 2 compared to Group 3 (60.6% versus 11.8%, p = 0.005, respectively). Similarly, these patients displayed a significantly higher ratio of aggressive PCa (ISUP grade > 2: 66.7% versus 23.5%, p = 0.027, respectively) and tumor infiltration (median tumor infiltration: 32.5% vs. 15%, p = 0.001, respectively) in the final specimen compared to Group 3. In conclusion, we have shown that radical prostatectomy without prior biopsy is safe in terms of the diagnosis of clinically significant PCa when proper preoperative risk stratification involving mpMRI and PSMA-PET imaging is applied.

Towards clinical implementation of circulating tumor DNA in metastatic prostate cancer: Opportunities for integration and pitfalls to interpretation

Plasma circulating tumor DNA (ctDNA) represents short fragments of tumor-derived DNA released into the bloodstream primarily from cancer cells undergoing apoptosis. In metastatic castration-resistant prostate cancer (mCRPC), characterizing genomic alterations in ctDNA identifies mutations, copy number alterations, and structural rearrangements with predictive and prognostic biomarker utility. These associations with clinical outcomes have resulted in ctDNA increasingly incorporated into routine clinical care. In this review, we summarize current and emerging applications for ctDNA analysis in metastatic prostate cancer, including outcome prediction, treatment selection, and characterization of treatment resistance. We also discuss potential pitfalls with interpreting ctDNA findings, namely false negatives arising from low tumor content and optimal assay design, including correction for clonal hematopoiesis of indeterminate potential and germline variants. Understanding the influence of these limitations on interpretation of ctDNA results is necessary to overcome barriers to clinical implementation. Nevertheless, as assay availability and technology continue to improve, recognizing both opportunities and shortcomings of ctDNA analysis will retain relevance with informing the implementation of precision-oncology initiatives for metastatic prostate cancer.

Cell-Free DNA Variant Sequencing Using Plasma and AR-V7 Testing of Circulating Tumor Cells in Prostate Cancer Patients

Prostate cancer (PCa) is the second most common malignant cancer and is a major cause of morbidity and mortality among men worldwide. There is still an urgent need for biomarkers applicable for diagnosis, prognosis, therapy prediction, or therapy monitoring in PCa. Liquid biopsies, including cell-free DNA (cfDNA) and circulating tumor cells (CTCs), are a valuable source for studying such biomarkers and are minimally invasive. In our study, we investigated the cfDNA of 34 progressive PCa patients, via targeted sequencing, for sequence variants and for the occurrence of CTCs, with a focus on androgen receptor splice variant 7 (AR-V7)-positive CTCs. The cfDNA content was associated with overall survival (OS; p = 0.014), disease-specific survival (DSS; p = 0.004), and time to treatment change (TTC; p = 0.001). Moreover, when considering all sequence variants grouped by their functional impact and allele frequency, a significant association with TTC (p = 0.017) was observed. When investigating only pathogenic or likely pathogenic gene variants, variants of the BRCA1 gene (p = 0.029) and the AR ligand-binding domain (p = 0.050) were associated with a shorter TTC. Likewise, the presence of CTCs was associated with a shorter TTC (p = 0.031). The presence of AR-V7-positive CTCs was associated with TTC (p < 0.001) in Kaplan–Meier analysis. Interestingly, all patients with AR-V7-positive CTCs also carried TP53 point mutations. Altogether, analysis of cfDNA and CTCs can provide complementary information that may support temporal and targeted treatment decisions and may elucidate the optimal choice within the variety of therapy options for advanced PCa patients.

Non-invasive Technology Advances in Cancer-A Review of the Advances in the Liquid Biopsy for Endometrial and Ovarian Cancers

Improving cancer survival rates globally requires improvements in disease detection and monitoring, with the aim of improving early diagnosis and prediction of disease relapse. Traditional means of detecting and monitoring cancers rely largely on imaging and, where possible, blood-based protein biomarkers, many of which are non-specific. Treatments are being improved by identification of inherited and acquired genomic aberrations in tumors, some of which can be targeted by newly developed therapeutic interventions. Treatment of gynecological malignancy is progressively moving toward personalized therapy, as exemplified by application of PARP-inhibition for patients with BRCA-deficient tubo-ovarian cancers, or checkpoint inhibition in patients with mismatch repair-deficient disease. However, the more recent discovery of a group of biomarkers described under the umbrella term of “liquid biopsy” promises significant improvement in our ability to detect and monitor cancers. The term “liquid biopsy” is used to describe an array of tumor-derived material found in blood plasma and other bodily fluids such as ascites, pleural fluid, saliva, and urine. It includes circulating tumors cells (CTCs), circulating nucleic acids including DNA, messenger RNA and micro RNAs, and extracellular vesicles (EVs). In this review, we discuss recent advancements in liquid biopsy for biomarker detection to help in diagnosis, prognosis, and planning of treatment of ovarian and endometrial cancer.

Seeding metastases: The role and clinical utility of circulating tumour cells

Peripheral human blood is a readily-accessible source of patient material in which circulating tumour cells (CTCs) can be found. Their isolation and characterization holds the potential to provide prognostic value for various solid cancers. Enumeration of CTCs from blood is becoming a common practice in informing prognosis and may guide therapy decisions. It is further recognized that enumeration alone does not capture perspective on the heterogeneity of tumours and varying functional abilities of the CTCs to interact with the secondary microenvironment. Characterizing the isolated CTCs further, in particular assessing their functional abilities, can track molecular changes in the disease progress. As a step towards identifying a suite of functional features of CTCs that could aid in clinical decisions, developing a CTC isolation technique based on extracellular matrix (ECM) interactions may provide a more solid foundation for isolating the cells of interest. Techniques based on size, charge, density, and single biomarkers are not sufficient as they underutilize other characteristics of cancer cells. The ability of cancer cells to interact with ECM proteins presents an opportunity to utilize their full character in capturing, and also allows assessment of the features that reveal how cells might behave at secondary sites during metastasis. This article will review some common techniques and recent advances in CTC capture technologies. It will further explore the heterogeneity of the CTC population, challenges they experience in their metastatic journey, and the advantages of utilizing an ECM-based platform for CTC capture. Lastly, we will discuss how tailored ECM approaches may present an optimal platform to capture an influential heterogeneous population of CTCs.

Single-molecule amplification-free multiplexed detection of circulating microRNA cancer biomarkers from serum

MicroRNAs (miRNAs) play essential roles in post-transcriptional gene expression and are also found freely circulating in bodily fluids such as blood. Dysregulated miRNA signatures have been associated with many diseases including cancer, and miRNA profiling from liquid biopsies offers a promising strategy for cancer diagnosis, prognosis and monitoring. Here, we develop size-encoded molecular probes that can be used for simultaneous electro-optical nanopore sensing of miRNAs, allowing for ultrasensitive, sequence-specific and multiplexed detection directly in unprocessed human serum, in sample volumes as small as 0.1 μl. We show that this approach allows for femtomolar sensitivity and single-base mismatch selectivity. We demonstrate the ability to simultaneously monitor miRNAs (miR-141-3p and miR-375-3p) from prostate cancer patients with active disease and in remission. This technology can pave the way for next generation of minimally invasive diagnostic and companion diagnostic tests for cancer.

Plasma Cell-Free DNA Profiling of PTEN-PI3K-AKT Pathway Aberrations in Metastatic Castration-Resistant Prostate Cancer

Tumor tissue from metastatic castration-resistant prostate cancer (mCRPC) harbors frequent copy number variations (CNVs) in the PTEN-PI3K-AKT pathway. However, identifying CNVs in plasma cell-free DNA (cfDNA) has proven to be challenging. With emerging data supporting Akt inhibition in PTEN-deficient mCRPC, we profiled PTEN-PI3K-AKT pathway aberrations in patients with mCRPC using a novel cfDNA assay optimized for CNV detection.

METHODS

A next-generation sequencing-based cfDNA assay was used to profile 231 patients with mCRPC from two independent cohorts (Australian, n = 78; United States, n = 153). PTEN-PI3K-AKT pathway genomic aberrations were correlated with clinical outcomes, including progression-free survival and overall survival (OS).

RESULTS

PTEN loss and PIK3CA gain were detected in 37% (85 of 231) and 17% (39 of 231) of patients, respectively. Poorer outcomes were observed in patients with PTEN-PI3K-AKT pathway aberrations, including those with dual PTEN loss and PIK3CA gain (hazard ratio 2.3, 95% CI 1.2 to 4.4). Cumulative CNV burden in the PTEN-PI3K-AKT and androgen receptor (AR) pathways was associated with significantly worse clinical outcomes (0 v 1 v ≥ 2 CNVs in Australian cohort: median OS 33.5 v 17.2 v 9.7 months, P < .001; 0 v 1 v ≥ 2 CNVs in US cohort: median OS 35.5 v 14.3 v 9.2 months, P < .001). Notably, 21% (31 of 146) of PTEN-neutral patients harbored alternative PTEN-PI3K-AKT pathway aberrations.

CONCLUSION

PTEN-PI3K-AKT pathway CNVs were readily detected using our cfDNA assay, with the prevalence of PTEN loss comparable with tissue-based studies. Additional PTEN-PI3K-AKT pathway aberrations were found in one fifth of PTEN-neutral cases. Concurrent CNVs in the PTEN-PI3K-AKT and AR pathways portended poor survival, and identifying this high-risk patient subset for dual AR/Akt inhibition may optimize precision treatment with Akt inhibitors in mCRPC.

Towards Routine Implementation of Liquid Biopsies in Cancer Management: It Is Always Too Early, until Suddenly It Is Too Late

Blood-based liquid biopsies are considered a new and promising diagnostic and monitoring tool for cancer. As liquid biopsies only require a blood draw, they are non-invasive, potentially more rapid and assumed to be a less costly alternative to genomic analysis of tissue biopsies. A multi-disciplinary workshop (n = 98 registrations) was organized to discuss routine implementation of liquid biopsies in cancer management. Real-time polls were used to engage with experts' about the current evidence of clinical utility and the barriers to implementation of liquid biopsies. Clinical, laboratory and health economics presentations were given to illustrate the opportunities and current levels of evidence, followed by three moderated break-out sessions to discuss applications. The workshop concluded that tumor-informed assays using next-generation sequencing (NGS) or PCR-based genotyping assays will most likely provide better clinical utility than tumor-agnostic assays, yet at a higher cost. For routine application, it will be essential to determine clinical utility, to define the minimum quality standards and performance of testing platforms and to ensure their use is integrated into current clinical workflows including how they complement tissue biopsies and imaging. Early health economic models may help identifying the most viable application of liquid biopsies. Alternative funding models for the translation of complex molecular diagnostics, such as liquid biopsies, may also be explored if clinical utility has been demonstrated and when their use is recommended in multi-disciplinary consensus guidelines.

Quantitative and Qualitative Analysis of Blood-based Liquid Biopsies to Inform Clinical Decision-making in Prostate Cancer

CONTEXT

Genomic stratification can impact prostate cancer (PC) care through diagnostic, prognostic, and predictive biomarkers that aid in clinical decision-making. The temporal and spatial genomic heterogeneity of PC together with the challenges of acquiring metastatic tissue biopsies hinder implementation of tissue-based molecular profiling in routine clinical practice. Blood-based liquid biopsies are an attractive, minimally invasive alternative.

OBJECTIVE

To review the clinical value of blood-based liquid biopsy assays in PC and identify potential applications to accelerate the development of precision medicine.

EVIDENCE ACQUISITION

A systematic review of PubMed/MEDLINE was performed to identify relevant literature on blood-based circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), and extracellular vesicles (EVs) in PC.

EVIDENCE SYNTHESIS

Liquid biopsy has emerged as a practical tool to profile tumor dynamics over time, elucidating features that evolve (genome, epigenome, transcriptome, and proteome) with tumor progression. Liquid biopsy tests encompass analysis of DNA, RNA, and proteins that can be detected in CTCs, ctDNA, or EVs. Blood-based liquid biopsies have demonstrated promise in the context of localized tumors (diagnostic signatures, risk stratification, and disease monitoring) and advanced disease (response/resistance biomarkers and prognostic markers).

CONCLUSIONS

Liquid biopsies have value as a source of prognostic, predictive, and response biomarkers in PC. Most clinical applications have been developed in the advanced metastatic setting, where CTC and ctDNA yields are significantly higher. However, standardization of assays and analytical/clinical validation is necessary prior to clinical implementation.

PATIENT SUMMARY

Traces of tumors can be isolated from blood samples from patients with prostate cancer either as whole cells or as DNA fragments. These traces provide information on tumor features. These minimally invasive tests can guide diagnosis and treatment selection.

Automated enumeration and phenotypic characterization of CTCs and tdEVs in patients with metastatic castration resistant prostate cancer

Background

Although most patients with metastatic castration-resistant prostate cancer (mCRPC) initially benefit from treatment with androgen receptor signaling inhibitors (ARSi), resistance inevitably occurs. Hence, we investigated the prognostic value of automated circulating tumor cell (CTC) and tumor-derived extracellular vesicle (tdEV) enumeration and their dynamics, in patients with mCRPC in the context of the initiation of treatment with ARSi. Furthermore, we hypothesize that CTC phenotypic heterogeneity might serve as a measurable biomarker under these circumstances.

Methods

Using an image analysis tool, we reanalyzed all CellSearch images previously acquired in the context of a prospective, multicenter clinical study for patients with mCRPC (n = 170) starting a new line of ARSi, for CTC and tdEV detection and enumeration. CTC (n = 19 129) phenotypic diversity was quantified by the Shannon index (SI). Progression-free survival (PFS) and overall survival (OS) were compared between groups of patients stratified according to CTC, tdEV, and SI levels.

Results

Automated CTC enumeration provided similar clinical prognostication compared with operator-based counts. Patients demonstrating high CTC phenotypic heterogeneity before therapy had a shorter median PFS (4.82 vs. 8.49 months, HR 1.79; P = 0.03) and OS (12.6 months vs. not reached, HR 2.32; P = 0.03), compared to patients with low diversity, irrespective of CTC level. Multivariable analysis showed how the prognostic value of the baseline SI was lost by pretreatment chemotherapy status, CTC counts, and PSA levels.

Conclusions

Automated CTC counts are a reliable substitute for reviewer-based enumeration, as they are equally informative for prognosis assessment in patients with mCRPC. Beyond enumeration, we demonstrated the added value of studying CTC phenotypic diversity for patient prognostication, warranting future investigation.

A Direct Comparison between the Lateral Magnetophoretic Microseparator and AdnaTest for Isolating Prostate Circulating Tumor Cells

Circulating tumor cells (CTCs) are important biomarkers for the diagnosis, prognosis, and treatment of cancer. However, because of their extreme rarity, a more precise technique for isolating CTCs is required to gain deeper insight into the characteristics of cancer. This study compares the performance of a lateral magnetophoretic microseparator (“CTC-μChip”), as a representative microfluidic device, and AdnaTest ProstateCancer (Qiagen), as a commercially available specialized method, for isolating CTCs from the blood of patients with prostate cancer. The enumeration and genetic analysis results of CTCs isolated via the two methods were compared under identical conditions. In the CTC enumeration experiment, the number of CTCs isolated by the CTC-μChip averaged 17.67 CTCs/mL, compared to 1.56 CTCs/mL by the AdnaTest. The number of contaminating white blood cells (WBCs) and the CTC purity with the CTC-μChip averaged 772.22 WBCs/mL and 3.91%, respectively, whereas those with the AdnaTest averaged 67.34 WBCs/mL and 1.98%, respectively. Through genetic analysis, using a cancer-specific gene panel (AR (androgen receptor), AR-V7 (A\androgen receptor variant-7), PSMA (prostate specific membrane antigen), KRT19 (cytokeratin-19), CD45 (PTPRC, Protein tyrosine phosphatase, receptor type, C)) with reverse transcription droplet digital PCR, three genes (AR, AR-V7, and PSMA) were more highly expressed in cells isolated by the CTC-μChip, while KRT19 and CD45 were similarly detected using both methods. Consequently, this study showed that the CTC-μChip can be used to isolate CTCs more reliably than AdnaTest ProstateCancer, as a specialized method for gene analysis of prostate CTCs, as well as more sensitively obtain cancer-associated gene expressions.

Detection of ctDNA in plasma of patients with clinically localised prostate cancer is associated with rapid disease progression

BACKGROUND

DNA originating from degenerate tumour cells can be detected in the circulation in many tumour types, where it can be used as a marker of disease burden as well as to monitor treatment response. Although circulating tumour DNA (ctDNA) measurement has prognostic/predictive value in metastatic prostate cancer, its utility in localised disease is unknown.

METHODS

We performed whole-genome sequencing of tumour-normal pairs in eight patients with clinically localised disease undergoing prostatectomy, identifying high confidence genomic aberrations. A bespoke DNA capture and amplification panel against the highest prevalence, highest confidence aberrations for each individual was designed and used to interrogate ctDNA isolated from plasma prospectively obtained pre- and post- (24 h and 6 weeks) surgery. In a separate cohort (n = 189), we identified the presence of ctDNA TP53 mutations in preoperative plasma in a retrospective cohort and determined its association with biochemical- and metastasis-free survival.

RESULTS

Tumour variants in ctDNA were positively identified pre-treatment in two of eight patients, which in both cases remained detectable postoperatively. Patients with tumour variants in ctDNA had extremely rapid disease recurrence and progression compared to those where variants could not be detected. In terms of aberrations targeted, single nucleotide and structural variants outperformed indels and copy number aberrations. Detection of ctDNA TP53 mutations was associated with a significantly shorter metastasis-free survival (6.2 vs. 9.5 years (HR 2.4; 95% CIs 1.2-4.8, p = 0.014).

CONCLUSIONS

CtDNA is uncommonly detected in localised prostate cancer, but its presence portends more rapidly progressive disease.

Combined Cell-free DNA and RNA Profiling of the Androgen Receptor: Clinical Utility of a Novel Multianalyte Liquid Biopsy Assay for Metastatic Prostate Cancer

BACKGROUND

The androgen receptor (AR) remains a critical driver in metastatic castration-resistant prostate cancer (mCRPC). Profiling AR aberrations in both circulating DNA and RNA may identify key predictive and/or prognostic biomarkers in the context of contemporary systemic therapy.

OBJECTIVE

To profile AR aberrations in circulating nucleic acids and correlate with clinical outcomes.

DESIGN, SETTING, AND PARTICIPANTS

We prospectively enrolled 67 mCRPC patients commencing AR pathway inhibitors (ARPIs; n = 41) or taxane chemotherapy (n = 26). Using a first-in-class next-generation sequencing-based assay, we performed integrated cell-free DNA (cfDNA) and cell-free RNA (cfRNA) profiling from a single 10 ml blood tube.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Kaplan-Meier survival estimates and multivariable Cox regression analyses were used to assess associations between clinical outcomes and the following AR aberrations: copy number variation, splice variants (AR-V7 and AR-V9) and somatic mutations.

RESULTS AND LIMITATIONS

Cell-free DNA and cfRNA were successfully sequenced in 67 (100%) and 59 (88%) patients, respectively. Thirty-six (54%) patients had one or more AR aberrations. AR gain and cumulative number of AR aberrations were independently associated with clinical/radiographic progression-free survival (PFS; hazard ratio [HR] 3.2, p = 0.01 and HR 3.0 for 0 vs ≥2, p = 0.04) and overall survival (HR 2.8, p = 0.04 and HR 2.9 for 0 vs ≥2, p = 0.03). Notably, concurrent AR gain and AR splice variant expression (AR gain/AR-V+) was associated with shorter prostate-specific antigen PFS on both ARPIs (HR 6.7, p = 0.009) and chemotherapy (HR 3.9, p = 0.04). Importantly, key findings were validated in an independent cohort of mCRPC patients (n = 40), including shorter OS in AR gain/AR-V+ disease (HR 3.3, p = 0.02). Limitations include sample size and follow-up period.

CONCLUSIONS

We demonstrate the utility of a novel, multianalyte liquid biopsy assay capable of simultaneously detecting AR alterations in cfDNA and cfRNA. Concurrent profiling of cfDNA and cfRNA may provide vital insights into disease biology and resistance mechanisms in mCRPC.

PATIENT SUMMARY

In this study of men with advanced prostate cancer, DNA and RNA abnormalities in the androgen receptor detected in blood were associated with poor outcomes on available drug treatments. This information could be used to better guide treatment of advanced prostate cancer.

Management of Patients with Advanced Prostate Cancer: Report of the Advanced Prostate Cancer Consensus Conference 2019

BACKGROUND

Innovations in treatments, imaging, and molecular characterisation in advanced prostate cancer have improved outcomes, but there are still many aspects of management that lack high-level evidence to inform clinical practice. The Advanced Prostate Cancer Consensus Conference (APCCC) 2019 addressed some of these topics to supplement guidelines that are based on level 1 evidence.

OBJECTIVE

To present the results from the APCCC 2019.

DESIGN, SETTING, AND PARTICIPANTS

Similar to prior conferences, experts identified 10 important areas of controversy regarding the management of advanced prostate cancer: locally advanced disease, biochemical recurrence after local therapy, treating the primary tumour in the metastatic setting, metastatic hormone-sensitive/naïve prostate cancer, nonmetastatic castration-resistant prostate cancer, metastatic castration-resistant prostate cancer, bone health and bone metastases, molecular characterisation of tissue and blood, inter- and intrapatient heterogeneity, and adverse effects of hormonal therapy and their management. A panel of 72 international prostate cancer experts developed the programme and the consensus questions.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The panel voted publicly but anonymously on 123 predefined questions, which were developed by both voting and nonvoting panel members prior to the conference following a modified Delphi process.

RESULTS AND LIMITATIONS

Panellists voted based on their opinions rather than a standard literature review or formal meta-analysis. The answer options for the consensus questions had varying degrees of support by the panel, as reflected in this article and the detailed voting results reported in the Supplementary material.

CONCLUSIONS

These voting results from a panel of prostate cancer experts can help clinicians and patients navigate controversial areas of advanced prostate management for which high-level evidence is sparse. However, diagnostic and treatment decisions should always be individualised based on patient-specific factors, such as disease extent and location, prior lines of therapy, comorbidities, and treatment preferences, together with current and emerging clinical evidence and logistic and economic constraints. Clinical trial enrolment for men with advanced prostate cancer should be strongly encouraged. Importantly, APCCC 2019 once again identified important questions that merit assessment in specifically designed trials.

PATIENT SUMMARY

The Advanced Prostate Cancer Consensus Conference provides a forum to discuss and debate current diagnostic and treatment options for patients with advanced prostate cancer. The conference, which has been held three times since 2015, aims to share the knowledge of world experts in prostate cancer management with health care providers worldwide. At the end of the conference, an expert panel discusses and votes on predefined consensus questions that target the most clinically relevant areas of advanced prostate cancer treatment. The results of the voting provide a practical guide to help clinicians discuss therapeutic options with patients as part of shared and multidisciplinary decision making.

Evaluation of Commercial Circulating Tumor DNA Test in Metastatic Prostate Cancer

PURPOSE

Circulating tumor DNA (ctDNA) sequencing provides a minimally invasive method for tumor molecular stratification. Commercial ctDNA sequencing is increasingly used in the clinic, but its accuracy in metastatic prostate cancer is untested. We compared the commercial Guardant360 ctDNA test against an academic sequencing approach for profiling metastatic prostate cancer.

PATIENTS AND METHODS

Plasma cell-free DNA was collected between September 2016 and April 2018 from 24 patients with clinically progressive metastatic prostate cancer representing a range of clinical scenarios. Each sample was analyzed using Guardant360 and a research panel encompassing 73 prostate cancer genes. Concordance of somatic mutation and copy number calls was evaluated between the two approaches.

RESULTS

Targeted sequencing independently confirmed 94% of somatic mutations identified by Guardant360 at an allele fraction greater than 1%. AR amplifications and mutations were detected with high concordance in 14 patients, with only three discordant subclonal mutations at an allele fraction lower than 0.5%. Many somatic mutations identified by Guardant360 at an allele fraction lower than 1% seemed to represent subclonal passenger events or non-prostate-derived clones. Most of the non-AR gene amplifications reported by Guardant360 represented single copy gains. The research approach detected several clinically relevant DNA repair gene alterations not reported by Guardant360, including four germline truncating BRCA2/ATM mutations, two somatic ATM stop gain mutations, one BRCA2 biallelic deletion, 11 BRCA2 stop gain reversal mutations in a patient treated with olaparib, and a hypermutator phenotype in a patient sample with 42 mutations per megabase.

CONCLUSION

Guardant360 accurately identifies somatic ctDNA mutations in patients with metastatic prostate cancer, but low allele frequency mutations should be interpreted with caution. Test utility in metastatic prostate cancer is currently limited by the lack of reporting on actionable deletions, rearrangements, and germline mutations.

Prognostic Utility of a Whole-blood Androgen Receptor-based Gene Signature in Metastatic Castration-resistant Prostate Cancer

BACKGROUND

The treatment paradigm for metastatic castration-resistant prostate cancer (mCRPC) has evolved significantly in recent years. Identifying predictive and/or prognostic biomarkers in the context of this rapidly expanding therapeutic armamentarium remains a pressing and unmet clinical need.

OBJECTIVE

To develop a prognostic whole-blood gene signature for mCRPC patients.

DESIGN, SETTING, AND PARTICIPANTS

As part of an ongoing prospective, multicentre biomarker research study (Australian Prostate Biomarker Alliance), we enrolled 115 mCRPC patients commencing chemotherapy (n = 34) or androgen receptor (AR) pathway inhibitors therapy (n = 81) and obtained pretreatment whole-blood samples in PAXgene RNA tubes. Gene expression was assessed using reverse transcription-polymerase chain reaction.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Gene transcripts correlating with overall survival (OS) at p < 0.10 in univariate Cox regression models were incorporated into a multigene signature. Kaplan-Meier survival estimates and multivariate analyses were used to assess association with clinical outcomes. Prognostic strength of the signature was estimated using a concordance probability estimate (CPE).

RESULTS AND LIMITATIONS

Based on univariate analysis for OS, the following genes were incorporated into a multigene signature: AR splice variant 7 (AR-V7), and three androgen-regulated genes: GRHL2, HOXB13, and FOXA1. The number of positive transcripts clearly stratified survival outcomes (median OS: not reached vs 24.8 mo vs 16.2 mo for 0, 1, and ≥2 transcripts, respectively; p = 0.0052). Notably, this multigene signature retained prognostic significance on multivariable analysis (hazard ratio, 2.1; 95% confidence interval, 1.1-4.0; p = 0.019). Moreover, CPE for this model was 0.78, indicating strong discriminative capacity. Limitations include short follow-up time.

CONCLUSIONS

Our data demonstrate the prognostic utility of a novel whole-blood AR-based signature in mCRPC patients commencing contemporary systemic therapies. Our pragmatic assay requires minimal processing, can be performed in most hospital laboratories, and could represent a key prognostic tool for risk stratification in mCRPC.

PATIENT SUMMARY

We found that expression of certain genes associated with the androgen receptor could help determine how long men with advanced prostate cancer survive after starting modern drug therapies.

Glycans as Biomarkers in Prostate Cancer

Prostate cancer is the most commonly diagnosed malignancy in men, claiming over350,000 lives worldwide annually. Current diagnosis relies on prostate-specific antigen (PSA)testing, but this misses some aggressive tumours, and leads to the overtreatment of non-harmfuldisease. Hence, there is an urgent unmet clinical need to identify new diagnostic and prognosticbiomarkers. As prostate cancer is a heterogeneous and multifocal disease, it is likely that multiplebiomarkers will be needed to guide clinical decisions. Fluid-based biomarkers would be ideal, andattention is now turning to minimally invasive liquid biopsies, which enable the analysis oftumour components in patient blood or urine. Effective diagnostics using liquid biopsies willrequire a multifaceted approach, and a recent high-profile review discussed combining multipleanalytes, including changes to the tumour transcriptome, epigenome, proteome, and metabolome.However, the concentration on genomics-based paramaters for analysing liquid biopsies ispotentially missing a goldmine. Glycans have shown huge promise as disease biomarkers, anddata suggests that integrating biomarkers across multi-omic platforms (including changes to theglycome) can improve the stratification of patients with prostate cancer. A wide range ofalterations to glycans have been observed in prostate cancer, including changes to PSAglycosylation, increased sialylation and core fucosylation, increased O-GlcNacylation, theemergence of cryptic and branched N-glyans, and changes to galectins and proteoglycans. In thisreview, we discuss the huge potential to exploit glycans as diagnostic and prognostic biomarkersfor prostate cancer, and argue that the inclusion of glycans in a multi-analyte liquid biopsy test forprostate cancer will help maximise clinical utility.

Neutrophil-to-lymphocyte Ratio as a Predictive Marker of Response to Abiraterone Acetate: A Retrospective Analysis of the COU302 Study

BACKGROUND

The neutrophil-lymphocyte ratio (NLR) is an inexpensive and accessible prognostic marker for many cancers, including metastatic castration-resistant prostate cancer (mCRPC).

OBJECTIVE

In this study, we assess the role of NLR as a predictive biomarker through a retrospective analysis of the pivotal COU302 study of abiraterone acetate (AA) as first-line therapy for men with asymptomatic or minimally symptomatic mCRPC.

DESIGN, SETTING, AND PARTICIPANTS

The COU302 study randomized asymptomatic or minimally symptomatic men with mCRPC to receive AA plus prednisone or prednisone as first-line treatment. Baseline NLR, overall survival, radiographic progression-free survival, and prostate-specific antigen (PSA) progression-free survival were evaluated.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Descriptive statistics, as well as Kaplan-Meier and Cox survival models were used to assess the effect of baseline NLR and changes in NLR on response to AA plus prednisone versus prednisone, with adjustment for important covariates.

RESULTS AND LIMITATIONS

Among the 1082 patients who received treatment, baseline NLR values showed no significant differences according to baseline covariates except for albumin. Baseline variables were similar between dichotomous groups with an NLR cutoff of 2.5, except for a lower proportion of patients with >10 bone metastases in the NLR <2.5 group. Our survival results demonstrate that higher NLR values corresponded to poorer overall survival and PSA response to AA but not to placebo, which was confirmed in our adjusted regression models. No significant differences were seen in time to radiographic progression. In separate analyses, an increase or decrease in NLR by 2 from treatment baseline did not clearly signal subsequent lack of benefit with continued AA.

CONCLUSIONS

Our results suggest that baseline NLR may be able to predict response to AA in men with asymptomatic mCRPC but that changes in NLR during treatment are insufficient to guide treatment. Further validation studies are warranted.

PATIENT SUMMARY

In this report, we look at the ratio of circulating immune cells as a predictor of response to abiraterone acetate (AA), using data from a large trial. Our results suggest that this ratio derived from routinely obtained bloodwork can predict which patients respond better to AA.