The TMPRSS2:ERG rearrangement, ERG expression, and prostate cancer outcomes: a cohort study and meta-analysis

A Prospective Study of Aspirin Use and Prostate Cancer Risk by TMPRSS2:ERG Status

Background: In a case-control study, aspirin use was associated with a lower risk of a common prostate cancer molecular subtype, the TMPRSS2:ERG gene fusion. We sought to validate this finding in a prospective cohort.Methods: In the Health Professionals Follow-up Study, 49,395 men reported on aspirin use on biennial questionnaires and were followed for prostate cancer incidence over 23 years. TMPRSS2:ERG status was assessed by IHC for presence of ERG on archival tumor specimens for 912 patients with prostate cancer, of whom 48% were ERG-positive.Results: In multivariable models, we found no association between regular use of aspirin and risk of ERG-positive prostate cancer (HR, 1.02; 95% confidence interval, 0.85-1.23), nor any association with duration or frequency of aspirin use. In restricting to cases with either high Gleason grade or advanced stage disease, there remained no association with aspirin use.Conclusions: Data from this prospective study with repeated assessments of aspirin use do not support the hypothesis that aspirin use is associated with a lower risk of ERG-positive prostate cancer.Impact: Aspirin use is unlikely to lower the risk of this common molecular subtype of prostate cancer. However, there is emerging data supporting the role of other lifestyle and genetic factors underlying the development of the TMPRSS2:ERG fusion. Cancer Epidemiol Biomarkers Prev; 27(10); 1231-3. ©2018 AACR.

Comparison of diagnostic efficacy by two urine PCA3 scores in prostate cancer patients undergoing repeat biopsies

INTRODUCTION

Urine prostate cancer gene 3 (PCA3) is significantly elevated in patients with prostate cancer and can be used for the diagnosis of prostate cancer, but its cutoff value is still controversial.

EVIDENCE ACQUISITION

We searched the database on urine PCA3 in the diagnosis of prostate cancer, such as Medline, Web of Science, the Cochrane Library and Embase. Meta-analysis was performed using the random effect model and the sensitivity, specificity, diagnostic odds ratio, and area under the ROC curve (SROC) were calculated.

EVIDENCE SYNTHESIS

Our meta-analysis included nine studies on PCA3 scores in a total of 1721 suspected prostate cancer patients. When urine PCA3 score was 20, we obtained sensitivity of 0.83, specificity of 0.40, diagnostic odds ratio of 3.11, and the area under the SROC curve was 0.6842 (Q value 0.6404). When urine PCA3 score was 35, we found a lower sensitivity of 0.66, a higher specificity of 0.63 and a relatively lower diagnostic odds ratio of 2.84. The area under the SROC curve was 0.6715, which was slightly lower than urine PCA3 score 20.

CONCLUSIONS

Our meta-analysis suggested that when the PCA3 score cutoff value was 20, the unnecessary puncture was reduced and obtained a higher diagnostic efficacy.

Predictive value of combined analysis of pro-NPY and ERG in localized prostate cancer

This study aimed to investigate if combined analysis of pro-Neuropeptide Y (NPY) and ERG expression in tumor tissue are associated with biochemical failure (BF), castration-based treatment, castration-resistant prostate cancer (CRPC), and prostate cancer (PCa)-specific death for men undergoing radical prostatectomy (RP) for PCa. This study included 315 patients, who underwent RP from 2002 to 2005. Both pro-NPY and ERG expression were analyzed using immunohistochemistry and were scored as low or high and negative or positive, respectively. Risk of BF, castration-based treatment, CRPC, and PCa-specific death were analyzed with multiple cause-specific Cox regression analyses and stratified cumulative incidences using competing risk assessment. Median follow-up was 13.0 years (95% CI: 12.7-13.2). In total, 85.7% were pro-NPY high and 14.3% were pro-NPY low. The combined analyses of pro-NPY and ERG expression was not associated with risk of BF (p = 0.7), castration-based treatment (p = 0.8), CRPC (p = 0.4) or PCa-specific death (p = 0.5). In the multiple cause-specific Cox regression analysis, pro-NPY high and ERG positivity was not associated with BF (HR: 1.02; 95% CI 0.6-1.7; p = 0.94). In conclusion the combination of pro-NPY and ERG expression did not show association with risk of BF, castration-based treatment, CRPC, and PCa-specific death following RP.

Prostate Cancer Disparities by Race and Ethnicity: From Nucleotide to Neighborhood

Prostate cancer (CaP) incidence, morbidity, and mortality rates vary substantially by race and ethnicity, with African American men experiencing among the highest CaP rates in the world. The causes of these disparities are multifactorial and complex, and likely involve differences in access to screening and treatment, exposure to CaP risk factors, variation in genomic susceptibility, and other biological factors. To date, the proportion of CaP that can be explained by environmental exposures is small and differences in the role factors play by race or ethnicity is poorly understood. In the absence of additional data, it is likely that environmental factors do not contribute greatly to CaP disparities. In contrast, CaP has one of the highest heritabilities of all major cancers and many CaP susceptibility genes have been identified. Some CaP loci, including the risk loci found at chromosome 8q24, have consistent effects in all racial/ethnic groups studied to date. However, replication of many susceptibility loci across race or ethnicity remains limited. It is likely that inequities in health care access strongly influences CaP disparities. CaP is a disease with a complex multifactorial etiology, and therefore any approach attempting to address racial/ethnic disparities in CaP must consider the many sources that influence risk, outcomes, and disparities.

Association between pathologic factors and ERG expression in prostate cancer: finding pivotal networking

PURPOSE

To evaluate associations between pathologic factors and erythroblast transformation-specific (ETS)-related gene (ERG) expression in prostate cancer patients. Using next-generation sequencing, we identified target genes and regulatory networks.

METHODS

ERG expression in 60 radical prostatectomies was compared with pathological findings by association rule mining with the Apriori algorithm. Whole-exome and RNA sequencing were performed on three formalin-fixed, paraffin-embedded ERG-positive and negative prostate cancer samples. A network diagram identifying dominant altered genes was constructed using Cytoscape open-source bioinformatics platform and GeneMania plugin.

RESULTS

Pathologic conditions positive for perineural invasion, apical margins, and Gleason score 3 + 4 = 7 were significantly more likely to be ERG-positive than other pathologic conditions (p = 0.0008), suggesting an association between ERG positivity, perineural invasion, apical margins, and Gleason score 3 + 4 = 7 (Firth's logistic regression: OR 42.565, 95% CI 1.670-1084.847, p = 0.0232). Results of whole-exome and RNA sequencing identified 97 somatic mutations containing common mutated genes. Regulatory network analysis identified NOTCH1, MEF2C, STAT3, LCK, CACNA2D3, PCSK7, MEF2A, PDZD2, TAB1, and ASGR1 as pivotal genes. NOTCH1 appears to function as a hub, because it had the highest node degree and betweenness. NOTCH1 staining was found 8 of 60 specimens (13%), with a significant association between ERG and NOTCH1 positivity (p = 0.001).

CONCLUSIONS

Evaluating the association between ERG expression and pathologic factors, and identifying the regulatory network and pivotal hub may help to understand the clinical significance of ERG-positive prostate cancer.

Systematic analysis reveals molecular characteristics of ERG-negative prostate cancer

The TMPRSS2:ERG gene fusion is the most prevalent early driver gene activation in prostate cancers of European ancestry, while the fusion frequency is much lower in Africans and Asians. The genomic characteristics and mechanisms for patients lacking ERG fusion are still unclear. In this study, we systematically compared the characteristics of gene fusions, somatic mutations, copy number alterations and gene expression signatures between 201 ERG fusion positive and 296 ERG fusion negative prostate cancer samples. Both common and group-specific genomic alterations were observed, suggesting shared and different mechanisms of carcinogenesis in prostate cancer samples with or without ERG fusion. The genomic alteration patterns detected in ERG-negative group showed similarities with 77.5% of tumor samples of African American patients. These results emphasize that genomic and gene expression features of the ERG-negative group may provide a reference for populations with lower ERG fusion frequency. While the overall expression patterns were comparable between ERG-negative and ERG-positive tumors, we found that genomic alterations could affect the same pathway through distinct genes in the same pathway in both groups of tumor types. Altogether, the genomic and molecular characteristics revealed in our study may provide new opportunities for molecular stratification of ERG-negative prostate cancers.

Dysregulation and prognostic potential of 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC) levels in prostate cancer

Background

Prognostic tools for prostate cancer (PC) are inadequate and new molecular biomarkers may improve risk stratification. The epigenetic mark 5-hydroxymethylcytosine (5hmC) has recently been proposed as a novel candidate prognostic biomarker in several malignancies including PC. 5hmC is an oxidized derivative of 5-methylcytosine (5mC) and can be further oxidized to 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). The present study is the first to investigate the biomarker potential in PC for all four DNA methylation marks in parallel. Thus, we determined 5mC, 5hmC, 5fC, and 5caC levels in non-malignant (NM) and PC tissue samples from a large radical prostatectomy (RP) patient cohort (n = 546) by immunohistochemical (IHC) analysis of serial sections of a tissue microarray. Possible associations between methylation marks, routine clinicopathological parameters, ERG status, and biochemical recurrence (BCR) after RP were investigated.

Results

5mC and 5hmC levels were significantly reduced in PC compared to NM prostate tissue samples (p ≤ 0.027) due to a global loss of both marks specifically in ERG− PCs. 5fC levels were significantly increased in ERG+ PCs (p = 0.004), whereas 5caC levels were elevated in both ERG− and ERG+ PCs compared with NM prostate tissue samples (p ≤ 0.019). Positive correlations were observed between 5mC, 5fC, and 5caC levels in both NM and PC tissues (p < 0.001), while 5hmC levels were only weakly positively correlated to 5mC in the PC subset (p = 0.030). There were no significant associations between 5mC, 5fC, or ERG status and time to BCR in this RP cohort. In contrast, high 5hmC levels were associated with BCR in ERG− PCs (p = 0.043), while high 5caC levels were associated with favorable prognosis in ERG+ PCs (p = 0.011) and were borderline significantly associated with worse prognosis in ERG− PCs (p = 0.058). Moreover, a combined high-5hmC/high-5caC score was a significant adverse predictor of post-operative BCR beyond routine clinicopathological variables in ERG− PCs (hazard ratio 3.18 (1.54–6.56), p = 0.002, multivariate Cox regression).

Conclusions

This is the first comprehensive study of 5mC, 5hmC, 5fC, and 5caC levels in PC and the first report of a significant prognostic potential for 5caC in PC.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0540-x) contains supplementary material, which is available to authorized users.

Correlation of Prostate Cancer CHD1 Status with Response to Androgen Deprivation Therapy: a Pilot Study

INTRODUCTION

CHD1 has been identified as a tumor suppressor gene in prostate cancer. Previous studies have shown strong associations between CHD1 deletion, prostate specific antigen [PSA] recurrence, and absence of ERG fusion. In this preliminary study we seek to find whether there is an independent correlation between CHD1 status and response to androgen deprivation therapy[ADT].

MATERIALS AND METHODS

We identified 11 patients with prostate cancer who underwent prostatectomy and received at least 7 months of ADT at our institution. They were divided into undetectable [PSA < 0.2 ng/mL; n = 8] and detectable [PSA > 0.2 ng/mL; n = 3] according to their serum PSA nadir after 7 months of ADT. Tissue microarray was generated from their formalin-fixed paraffin-embedded prostatectomy and involved lymph node tissues. Fluorescence in situ hybridization [FISH] analysis for CHD1 and immunohistochemical stains for PSA, AR, PTEN, ERG and SPINK1 were performed.

RESULTS

Our results showed heterogeneity of FISH and immunostains expressions in different foci of tumor. Status of CHD1, ERG, PTEN, or SPINK1 did not correlate with one another or with response to ADT.

CONCLUSIONS

Additional larger studies may be needed to further elucidate trends between these biomarkers and clinical outcomes in prostate cancer patients.

Molecular Subtypes of Prostate Cancer

PURPOSE OF REVIEW

This review will examine the taxonomy of PCa subclasses across disease states, explore the relationship among specific alterations, and highlight current clinical relevance.

RECENT FINDINGS

Prostate cancer (PCa) is driven by multiple genomic alterations, with distinct patterns and clinical implications. Alterations occurring early in the timeline of the disease define core subtypes of localized, treatment-naive PCa. With time, an increase in number and severity of genomic alterations adds molecular complexity and is associated with progression to metastasis. These later events are not random and are influenced by the underlying subclasses. All the subclasses of localized disease initially respond to androgen deprivation therapy (ADT), but with progression to castrate-resistant PCa (CRPC), mechanisms of resistance against ADT shift the molecular landscape. In CRPC, resistance mechanisms largely define the biology and sub-classification of these cancers, while clinical relevance and opportunities for precision therapy are still being defined.

Genomes of early onset prostate cancer

PURPOSE OF REVIEW

Prostate cancer is a disease of the elderly but a clinically relevant subset occurs early in life. In the current review, we discuss recent findings and the current understanding of the molecular underpinnings associated with early-onset prostate cancer (PCa) and the evidence supporting age-specific differences in the cancer genomes.

RECENT FINDINGS

Recent surveys of PCa patient cohorts have provided novel age-dependent links between germline and somatic aberrations which points to differences in the molecular cause and treatment options.

SUMMARY

Identifying the earliest molecular alterations in PCa can provide insight into the cause of the disease and biomarkers for patient risk stratification. Genomic aberrations of early-onset PCas display several patterns distinct from late-onset PCa genomes, suggesting age-dependent pathomechanisms involving alterations in the androgen receptor pathway.

Docetaxel Treatment in PTEN- and ERG-aberrant Metastatic Prostate Cancers

BACKGROUND

Loss of PTEN is a common genomic aberration in castration-resistant prostate cancer (CRPC) and is frequently concurrent with ERG rearrangements, causing resistance to next-generation hormonal treatment (NGHT) including abiraterone. The relationship between PTEN loss and docetaxel sensitivity remains uncertain.

OBJECTIVE

To study the antitumor activity of docetaxel in metastatic CRPC in relation to PTEN and ERG aberrations.

DESIGN SETTING AND PARTICIPANTS

Single-centre, retrospective analysis of PTEN loss and ERG expression using a previously described immunohistochemistry (IHC) binary classification system. Patients received docetaxel between January 1, 2006 and July 31, 2016.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Response correlations were analyzed using Pearson's χ2 tests and independent-sample t tests. Overall (OS) and progression-free survival (PFS) were analyzed using univariate and multivariate (MVA) Cox regression and Kaplan-Meier methods.

RESULTS AND LIMITATIONS

Overall, 215 patients were eligible. Established metastatic CRPC prognostic factors were well balanced between PTEN loss (39%) and normal patients (61%). PTEN loss was associated with shorter median OS (25.4 vs 34.7 mo; hazard ratio [HR] 1.66, 95% confidence interval [CI] 1.18-2.13; p = 0.001). There were no differences in median PFS (8.0 vs 9.1 mo; univariate HR 1.20, 95% CI 0.86-1.68; p = 0.28) and PSA response (53.4% vs 50.6%; p = 0.74). PTEN loss was an independent prognostics factor in MVA. ERG status was available for 100 patients. ERG positivity was not associated with OS or PFS. Limitations include the retrospective nature and the single-centre analysis.

CONCLUSIONS

Our findings suggest that metastatic CRPC with PTEN loss might benefit more from docetaxel than from NGHT.

PATIENT SUMMARY

In this study we found that metastatic prostate cancer with loss of the PTEN switch may benefit more from docetaxel than from abiraterone.

The androgen receptor malignancy shift in prostate cancer

BACKGROUND

Androgens and the androgen receptor (AR) are necessary for the development, function, and homeostatic growth regulation of the prostate gland. However, once prostate cells are transformed, the AR is necessary for the proliferation and survival of the malignant cells. This change in AR function appears to occur in nearly every prostate cancer. We have termed this the AR malignancy shift.

METHODS

In this review, we summarize the current knowledge of the AR malignancy shift, including the DNA-binding patterns that define the shift, the transcriptome changes associated with the shift, the putative drivers of the shift, and its clinical implications.

RESULTS

In benign prostate epithelial cells, the AR primarily binds consensus AR binding sites. In carcinoma cells, the AR cistrome is dramatically altered, as the AR associates with FOXA1 and HOXB13 motifs, among others. This shift leads to the transcription of genes associated with a malignant phenotype. In model systems, some mutations commonly found in localized prostate cancer can alter the AR cistrome, consistent with the AR malignancy shift. Current evidence suggests that the AR malignancy shift is necessary but not sufficient for transformation of prostate epithelial cells.

CONCLUSIONS

Reinterpretation of prostate cancer genomic classification systems in light of the AR malignancy shift may improve our ability to predict clinical outcomes and treat patients appropriately. Identifying and targeting the molecular factors that contribute to the AR malignancy shift is not trivial but by doing so, we may be able to develop new strategies for the treatment or prevention of prostate cancer.

Emerging proteomics biomarkers and prostate cancer burden in Africa

Various biomarkers have emerged via high throughput omics-based approaches for use in diagnosis, treatment, and monitoring of prostate cancer. Many of these have yet to be demonstrated as having value in routine clinical practice. Moreover, there is a dearth of information on validation of these emerging prostate biomarkers within African cohorts, despite the huge burden and aggressiveness of prostate cancer in men of African descent. This review focusses of the global landmark achievements in prostate cancer proteomics biomarker discovery and the potential for clinical implementation of these biomarkers in Africa. Biomarker validation processes at the preclinical, translational and clinical research level are discussed here, as are the challenges and prospects for the evaluation and use of novel proteomic prostate cancer biomarkers.

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.

Status of TMPRSS2-ERG fusion in prostate cancer patients from India: correlation with clinico-pathological details and TMPRSS2 Met160Val polymorphism

Background

Prostate cancer (PCa) shows considerable clinical heterogeneity that has been primarily attributed to variable molecular alterations. TMPRSS2-ERG fusion is one such molecular subtype that has been associated with predominantly poor prognosis. More recently, a single nucleotide polymorphism (SNP) in the TMPRSS2 gene rs12329760 C>T (Met160Val) has been shown to positively correlate with the fusion status and also to be associated with increased risk for PCa. The aim of the present study is to determine the frequency of TMPRSS2-ERG fusion and association of rs12329760 in Indian PCa patients with fusion status.

Methods

TMPRSS2-ERG fusion by fluorescence in situ hybridization was determined in 102 of 150 PCa biopsy-proven cases. Genotyping for rs12329760 was performed on the entire cohort of 150 cases by Sanger sequencing.

Results

TMPRSS2-ERG fusion was seen in 27 of 102 (26%) cases. Fusion-positive patterns in this study showed fusion by translocation in nine of 27 cases (33.5%), by deletion in six of 27 (22%) cases, and by insertion in 12 of 27 cases (44.5%). No association of the fusion status with Gleason Score, pattern, or perineural invasion was seen. The TMPRSS2 SNP rs12329760 'T' allele was prevalent with a frequency of 0.27 in the PCa patients. The SNP was significantly associated with fusion [odds ratio (OR) = 2.176, 95% confidence interval (CI) = 1.012-4.684, P = 0.04], more specifically fusion by deletion (P = 0.04).

Conclusion

The results provided here determine the frequency of TMPRSS2-ERG fusions (26%) in a fairly large cohort of Indian PCa cases and also the association of rs12329760 SNP with TMPRSS2-ERG fusion. No association with other clinico-pathological features was observed. Future studies with clinical outcomes are warranted in this population.

Clinical implications of PTEN loss in prostate cancer

Genomic aberrations of the PTEN tumour suppressor gene are among the most common in prostate cancer. Inactivation of PTEN by deletion or mutation is identified in ∼20% of primary prostate tumour samples at radical prostatectomy and in as many as 50% of castration-resistant tumours. Loss of phosphatase and tensin homologue (PTEN) function leads to activation of the PI3K-AKT (phosphoinositide 3-kinase-RAC-alpha serine/threonine-protein kinase) pathway and is strongly associated with adverse oncological outcomes, making PTEN a potentially useful genomic marker to distinguish indolent from aggressive disease in patients with clinically localized tumours. At the other end of the disease spectrum, therapeutic compounds targeting nodes in the PI3K-AKT-mTOR (mechanistic target of rapamycin) signalling pathway are being tested in clinical trials for patients with metastatic castration-resistant prostate cancer. Knowledge of PTEN status might be helpful to identify patients who are more likely to benefit from these therapies. To enable the use of PTEN status as a prognostic and predictive biomarker, analytically validated assays have been developed for reliable and reproducible detection of PTEN loss in tumour tissue and in blood liquid biopsies. The use of clinical-grade assays in tumour tissue has shown a robust correlation between loss of PTEN and its protein as well as a strong association between PTEN loss and adverse pathological features and oncological outcomes. In advanced disease, assessing PTEN status in liquid biopsies shows promise in predicting response to targeted therapy. Finally, studies have shown that PTEN might have additional functions that are independent of the PI3K-AKT pathway, including those affecting tumour growth through modulation of the immune response and tumour microenvironment.

Presence of TMPRSS2-ERG is associated with alterations of the metabolic profile in human prostate cancer

TMPRSS2-ERG has been proposed to be a prognostic marker for prostate cancer. The aim of this study was to identify changes in metabolism, genes and biochemical recurrence related to TMPRSS2-ERG by using an integrated approach, combining metabolomics, transcriptomics, histopathology and clinical data in a cohort of 129 human prostate samples (41 patients). Metabolic analyses revealed lower concentrations of citrate and spermine comparing ERG_high to ERG_low samples, suggesting an increased cancer aggressiveness of ERG_high compared to ERG_low. These results could be validated in a separate cohort, consisting of 40 samples (40 patients), and magnetic resonance spectroscopy imaging (MRSI) indicated an in vivo translational potential. Alterations of gene expression levels associated with key enzymes in the metabolism of citrate and polyamines were in consistence with the metabolic results. Furthermore, the metabolic alterations between ERG_high and ERG_low were more pronounced in low Gleason samples than in high Gleason samples, suggesting it as a potential tool for risk stratification. However, no significant difference in biochemical recurrence was detected, although a trend towards significance was detected for low Gleason samples. Using an integrated approach, this study suggests TMPRSS2-ERG as a potential risk stratification tool for inclusion of active surveillance patients.

Markers of clinical utility in the differential diagnosis and prognosis of prostate cancer

Molecular diagnostics is a rapidly evolving area of surgical pathology, that is gradually beginning to transform our diagnostical procedures for a variety of tumors. Next to molecular prognostication that has begun to complement our histological diagnosis in breast cancer, additional testing to detect targets and to predict therapy response has become common practice in breast and lung cancer. Prostate cancer is a bit slower in this respect, as it is still largely diagnosed and classified on morphological grounds. Our diagnostic immunohistochemical armamentarium of basal cell markers and positive markers of malignancy now allows to clarify the majority of lesions, if applied to the appropriate morphological context (and step sections). Prognostic immunohistochemistry remains a problematic and erratic yet tempting research field that provides information on tumor relevance of proteins, but little hard data to integrate into our diagnostic workflow. Main reasons are various issues of standardization that hamper the reproducibility of cut-off values to delineate risk categories. Molecular testing of DNA-methylation or transcript profiling may be much better standardized and this review discusses a couple of commercially available tests: The ConfirmDX test measures DNA-methylation to estimate the likelihood of cancer detection on a repeat biopsy and may help to reduce unnecessary biopsies. The tests Prolaris, OncotypeDX Prostate, and Decipher all are transcript tests that have shown to provide prognostic data independent of clinico-pathological parameters and that may aid in therapy planning. However, further validation and more comparative studies will be needed to clarify the many open questions concerning sampling bias and tumor heterogeneity.

mTOR pathway activation is a favorable prognostic factor in human prostate adenocarcinoma

Prostate cancer patients with localized disease are treated with curative intent. However, the disease will recur in approximately 30% of patients with a high incidence of morbidity and mortality. Prognostic biomarkers are needed to identify patients with high risk of relapse. mTOR pathway activation is reported in prostate cancer, but clinical trials testing efficacy of mTOR inhibitors were unsuccessful. To explain this clinical observation, we studied the expression and prognostic impact of mTOR-S2448 phosphorylation in localized prostate carcinomas. mTOR-S2448 phosphorylation is indicative for an activated mTOR pathway in prostate cancer. Surprisingly, the mTOR signaling pathway is activated specifically in prostate cancer patients with a favorable outcome. Since tumors from poor-outcome patients have low levels of mTOR-S2448 phosphorylation, this may explain why mTOR inhibitors proved unsuccessful in prostate cancer trials.

TMPRSS2:ERG Gene Fusions in Prostate Cancer of West African Men and a Meta-Analysis of Racial Differences

The prevalence of fusions of the transmembrane protease, serine 2, gene (TMPRSS2) with the erythroblast transformation-specific-related gene (ERG), or TMPRSS2:ERG, in prostate cancer varies by race. However, such somatic aberration and its association with prognostic factors have neither been studied in a West African population nor been systematically reviewed in the context of racial differences. We used immunohistochemistry to assess oncoprotein encoded by the ERG gene as the established surrogate of ERG fusion genes among 262 prostate cancer biopsies from the Ghana Prostate Study (2004-2006). Poisson regression with robust variance estimation provided prevalence ratios and 95% confidence intervals of ERG expression in relation to patient characteristics. We found that 47 of 262 (18%) prostate cancers were ERG-positive, and being negative for ERG staining was associated with higher Gleason score. We further conducted a systematic review and meta-analysis of TMPRSS2:ERG fusions in relation to race, Gleason score, and tumor stage, combining results from Ghana with 40 additional studies. Meta-analysis showed the prevalence of TMPRSS2:ERG fusions in prostate cancer to be highest in men of European descent (49%), followed by men of Asian (27%) and then African (25%) descent. The lower prevalence of TMPRSS2:ERG fusions in men of African descent implies that alternative genomic mechanisms might explain the disproportionately high prostate cancer burden in such populations.

Height, Obesity, and the Risk of TMPRSS2:ERG-Defined Prostate Cancer

Background: The largest molecular subtype of primary prostate cancer is defined by the TMPRSS2:ERG gene fusion. Few studies, however, have investigated etiologic differences by TMPRSS2:ERG status. Because the fusion is hormone-regulated and a man's hormonal milieu varies by height and obesity status, we hypothesized that both may be differentially associated with risk of TMPRSS2:ERG-defined disease.Methods: Our study included 49,372 men from the prospective Health Professionals Follow-up Study. Participants reported height and weight at baseline in 1986 and updated weight biennially thereafter through 2009. Tumor ERG protein expression (a TMPRSS2:ERG marker) was immunohistochemically assessed. We used multivariable competing risks models to calculate HRs and 95% confidence intervals (CIs) for the risk of ERG-positive and ERG-negative prostate cancer.Results: During 23 years of follow-up, we identified 5,847 incident prostate cancers, among which 913 were ERG-assayed. Taller height was associated with an increased risk of ERG-positive disease only [per 5 inches HR 1.24; 95% confidence interval (CI), 1.03-1.50; P_{heterogeneity} = 0.07]. Higher body mass index (BMI) at baseline (per 5 kg/m² HR 0.75; 95% CI, 0.61-0.91; P_{heterogeneity} = 0.02) and updated BMI over time (per 5 kg/m² HR 0.86; 95% CI, 0.74-1.00; P_{heterogeneity} = 0.07) were associated with a reduced risk of ERG-positive disease only.Conclusions: Our results indicate that anthropometrics may be uniquely associated with TMPRSS2:ERG-positive prostate cancer; taller height may be associated with greater risk, whereas obesity may be associated with lower risk.Impact: Our study provides strong rationale for further investigations of other prostate cancer risk factors that may be distinctly associated with subtypes. Cancer Epidemiol Biomarkers Prev; 27(2); 193-200. ©2017 AACR.

Biomarkers in prostate cancer - Current clinical utility and future perspectives

Current tendencies in the treatment course of prostate cancer patients increase the need for reliable biomarkers that help in decision-making in a challenging clinical setting. Within the last decade, several novel biomarkers have been introduced. In the following comprehensive review article, we focus on diagnostic (PHI^®, 4K score, SelectMDx^®, ConfirmMDx^®, PCA3, MiPS, ExoDX^®, mpMRI) and prognostic (OncotypeDX GPS^®, Prolaris^®, ProMark^®, DNA-ploidy, Decipher^®) biomarkers that are in widespread clinical use and are supported by evidence. Hereby, we focus on multiple clinical situations in which innovative biomarkers may guide decision-making in prostate cancer therapy. In addition, we describe novel liquid biopsy approaches (circulating tumor cells, cell-free DNA) that have been described as predictive biomarkers in metastatic castration-resistant prostate cancer and might support an individual patient-centred oncological approach in the nearer future.

Retention of Interstitial Genes between TMPRSS2 and ERG Is Associated with Low-Risk Prostate Cancer

TMPRSS2-ERG gene fusions occur in over 50% of prostate cancers, but their impact on clinical outcomes is not well understood. Retention of interstitial genes between TMPRSS2 and ERG has been reported to influence tumor progression in an animal model. In this study, we analyzed the status of TMPRSS2-ERG fusion genes and interstitial genes in tumors from a large cohort of men treated surgically for prostate cancer, associating alterations with biochemical progression. Through whole-genome mate pair sequencing, we mapped and classified rearrangements driving ETS family gene fusions in 133 cases of very low-, low-, intermediate-, and high-risk prostate cancer from radical prostatectomy specimens. TMPRSS2-ERG gene fusions were observed in 44% of cases, and over 90% of these fusions occurred in ERG exons 3 or 4. ERG fusions retaining interstitial sequences occurred more frequently in very low-risk tumors. These tumors also frequently displayed ERG gene fusions involving alternative 5'-partners to TMPRSS2, specifically SLC45A3 and NDRG1 and other ETS family genes, which retained interstitial TMPRSS2/ERG sequences. Lastly, tumors displaying TMPRSS2-ERG fusions that retained interstitial genes were less likely to be associated with biochemical recurrence (P = 0.028). Our results point to more favorable clinical outcomes in patients with ETS family fusion-positive prostate cancers, which retain potential tumor-suppressor genes in the interstitial regions between TMPRSS2 and ERG Identifying these patients at biopsy might improve patient management, particularly with regard to active surveillance. Cancer Res; 77(22); 6157-67. ©2017 AACR.

PTEN loss is associated with prostate cancer recurrence and alterations in tumor DNA methylation profiles

BACKGROUND

Prostate cancer (PCa) with loss of the tumor suppressor gene PTEN has an unfavorable prognosis. DNA methylation profiles associated with PTEN loss may provide further insights into the mechanisms underlying these more aggressive, clinically relevant tumors.

METHODS

The cohort included patients with clinically localized PCa. Samples taken from the primary tumor were used to determine PTEN genomic deletions using FISH, and to analyze epigenome-wide DNA methylation profiles. Patients were followed for PCa recurrence on average for 8 years after diagnosis.

RESULTS

The study included 471 patients with data on PTEN loss, and the frequency of hemi- and homozygous PTEN loss was 10.0% and 4.5%, respectively. Loss of PTEN was associated with a significantly higher risk of recurrence (any vs. no PTEN loss; HR = 1.74; 95% CI: 1.03-2.93). Hazard ratios for hemi- and homozygous loss were 1.39 (95% CI: 0.73-2.64) and 2.84 (95% CI: 1.30-6.19), respectively. Epigenome-wide methylation profiling identified 4,208 differentially methylated CpGs (FDR Q-value < 0.01) in tumors with any versus no PTEN loss. There were no genome-wide significant differentially methylated CpGs in homo- versus hemizygous deleted tumors. Tumor methylation data were used to build a methylation signature of PTEN loss in our cohort, which was confirmed in TCGA, and included CpGs in ATP11A, GDNF, JAK1, JAM3, and VAPA.

CONCLUSION

Loss of PTEN was positively associated with PCa recurrence. Prostate tumors with PTEN loss harbor a distinct methylation signature, and these aberrantly methylated CpG sites may mediate tumor progression when PTEN is deleted.

Somatic molecular subtyping of prostate tumors from HOXB13 G84E carriers

A recurrent germline mutation (G84E) in the HOXB13 gene is associated with early onset and family history-positive prostate cancer in patients of European descent, occurring in up to 5% of prostate cancer families. To date, the molecular features of prostate tumors occurring in HOXB13 G84E carriers have not been studied in a large cohort of patients. We identified 101 heterozygous carriers of G84E who underwent radical prostatectomy for prostate cancer between 1985 and 2011 and matched these men by race, age and tumor grade to 99 HOXB13 wild-type controls. Immunostaining for HOXB13, PTEN, ERG, p53 and SPINK1 as well as RNA in situ hybridization for ETV1/4/5 were performed using genetically validated assays. Tumors from G84E carriers generally expressed HOXB13 protein at a level comparable to benign and wild-type glands. ETS gene expression (either ERG or ETV1/4/5) was seen in 36% (36/101) of tumors from G84E carriers compared to 68% (65/96) of the controls (p < 0.0001). PTEN was lost in 11% (11/101) of G84E carriers compared to 25% (25/99) of the controls (p = 0.014). PTEN loss was enriched among ERG-positive compared to ERG-negative tumors in both groups of patients. Nuclear accumulation of the p53 protein, indicative of underlying TP53 missense mutations, was uncommon in both groups, occurring in 1% (1/101) of the G84E carriers versus 2% (2/92) of the controls (p = NS). Taken together, these data suggest that genes other than ERG and PTEN may drive carcinogenesis/progression in the majority of men with germline HOXB13 mutations.

Association Between Combined TMPRSS2:ERG and PCA3 RNA Urinary Testing and Detection of Aggressive Prostate Cancer

Importance

Potential survival benefits from treating aggressive (Gleason score, ≥7) early-stage prostate cancer are undermined by harms from unnecessary prostate biopsy and overdiagnosis of indolent disease.

Objective

To evaluate the a priori primary hypothesis that combined measurement of PCA3 and TMPRSS2:ERG (T2:ERG) RNA in the urine after digital rectal examination would improve specificity over measurement of prostate-specific antigen alone for detecting cancer with Gleason score of 7 or higher. As a secondary objective, to evaluate the potential effect of such urine RNA testing on health care costs.

Design, Setting, and Participants

Prospective, multicenter diagnostic evaluation and validation in academic and community-based ambulatory urology clinics. Participants were a referred sample of men presenting for first-time prostate biopsy without preexisting prostate cancer: 516 eligible participants from among 748 prospective cohort participants in the developmental cohort and 561 eligible participants from 928 in the validation cohort.

Interventions/Exposures

Urinary PCA3 and T2:ERG RNA measurement before prostate biopsy.

Main Outcomes and Measures

Presence of prostate cancer having Gleason score of 7 or higher on prostate biopsy. Pathology testing was blinded to urine assay results. In the developmental cohort, a multiplex decision algorithm was constructed using urine RNA assays to optimize specificity while maintaining 95% sensitivity for predicting aggressive prostate cancer at initial biopsy. Findings were validated in a separate multicenter cohort via prespecified analysis, blinded per prospective-specimen-collection, retrospective-blinded-evaluation (PRoBE) criteria. Cost effects of the urinary testing strategy were evaluated by modeling observed biopsy results and previously reported treatment outcomes.

Results

Among the 516 men in the developmental cohort (mean age, 62 years; range, 33-85 years) combining testing of urinary T2:ERG and PCA3 at thresholds that preserved 95% sensitivity for detecting aggressive prostate cancer improved specificity from 18% to 39%. Among the 561 men in the validation cohort (mean age, 62 years; range, 27-86 years), analysis confirmed improvement in specificity (from 17% to 33%; lower bound of 1-sided 95% CI, 0.73%; prespecified 1-sided P = .04), while high sensitivity (93%) was preserved for aggressive prostate cancer detection. Forty-two percent of unnecessary prostate biopsies would have been averted by using the urine assay results to select men for biopsy. Cost analysis suggested that this urinary testing algorithm to restrict prostate biopsy has greater potential cost-benefit in younger men.

Conclusions and Relevance

Combined urinary testing for T2:ERG and PCA3 can avert unnecessary biopsy while retaining robust sensitivity for detecting aggressive prostate cancer with consequent potential health care cost savings.

Tissue-based biomarkers in prostate cancer

INTRODUCTION

Prostate cancer is a heterogeneous disease. Existing risk stratification tools based on standard clinlicopathologic variables (prostate specific antigen [PSA], Gleason score, and tumor stage) provide a modest degree of predictive ability. Advances in high-throughput sequencing has led to the development of several novel tissue-based biomarkers that can improve prognostication in prostate cancer management.

AREAS COVERED

The authors review commercially-available, tissue-based biomarker assays that improve upon existing risk-stratification tools in several areas of prostate cancer management, including the appropriateness of active surveillance and aiding in decision making regarding the use of adjuvant therapy. Additionally, some of the obstacles to the widespread adoption of these biomarkers and discuss several investigational sources of new biomarkers are discussed.

EXPERT COMMENTARY

Work is ongoing to answer pertinent clinical questions in prostate cancer management including which patients should undergo biopsy, active surveillance, receive adjuvant therapy, and what systemic therapy is best in the first-line. Incorporation into novel biomarkers may allow for the incorporation of a 'personalized' approach to management. Further validation will be required and questions of cost must be considered before wide scale adoption of these biomarkers. Tumor heterogeneity may impose a ceiling on the prognostic ability of biomarkers using currently available techniques.

Ethnicity and ERG frequency in prostate cancer

Emerging observations emphasize a distinct biology of prostate cancer among men of different ethnicities and races, as demonstrated by remarkable differences in the frequency of ERG oncogenic activation, one of the most common and widely studied prostate cancer driver genes. Worldwide assessment of ERG alterations frequencies show consistent trends, with men of European ancestry having the highest rates of alteration and men of African or Asian ancestries having considerably lower alteration rates. However, data must be interpreted cautiously, owing to variations in assay platforms and specimen types, as well as ethnic and geographical classifications. Many opportunities and challenges remain in assessing cancer-associated molecular alterations at a global level, and these need to be addressed in order to realize the true potential of precision medicine for all cancer patients.

Managing high-grade prostatic intraepithelial neoplasia (HGPIN) and atypical glands on prostate biopsy

Prostate biopsy is the gold standard for diagnosing prostate cancer and reliable pathological assessment is essential for guiding management. Research efforts over the past few years have aimed to establish a more universal approach to management according to pathological grading; however, high-grade prostatic intraepithelial neoplasia (HGPIN) and atypical glands suspicious for carcinoma are two diagnoses without standardized follow-up and treatment pathways. Much of this uncertainty is due to limited evidence describing the subsequent rates of cancer and high-grade cancer when HGPIN or atypical glands are detected on initial biopsy. Fortunately, data from the past decade have shed light on these phenomena, and an improved understanding of the implications of the presence of HGPIN and atypical glands on prostate biopsy means that clinical recommendations can be made for the management of patients with these diagnoses.

Significance of the TMPRSS2:ERG gene fusion in prostate cancer

The transmembrane protease serine 2:v-ets erythroblastosis virus E26 oncogene homolog (TMPRSS2:ERG) gene fusion is common in prostate cancer, while its functional role is not fully understood. The present study aimed to investigate the significance of the TMPRSS2:ERG gene fusion in human prostate cancers using bioinformatics tools. Comprehensive alteration analysis of TMPRSS2 and ERG in 148 different human cancer studies was performed by cBioPortal, and the mRNA expression level of the ERG gene was evaluated using Oncomine analysis. Furthermore, lentiviral short hairpin (sh)RNA-mediated knockdown of TMPRSS2:ERG was performed to study the impact of ERG silencing on cell proliferation and cell cycle distribution in prostate cancer cells. The results demonstrated that the TMPRSS2 and ERG genes were mostly altered in prostate cancer, and the most frequent alteration was gene fusion. Oncomine analysis demonstrated that the ERG gene was significantly upregulated in prostate clinical samples compared with the normal prostate gland in four independent datasets, and a positive association was observed between potassium inwardly-rectifying channel subfamily J member 15, down syndrome critical region gene 4, potassium inwardly-rectifying channel subfamily J member 6 and ERG gene expression. There were 272 mutations of the ERG gene identified in the cBioPortal database; among the mutations, 2 missense mutations (R367C and P401H) were regarded as functional mutations (functional impact score >1.938). Furthermore, the present study successfully knocked down ERG gene expression through a lentiviral-mediated gene silencing approach in VCaP prostate cancer cells. The ERG mRNA and protein expression levels were both suppressed significantly, and a cell-cycle arrest at G₀/G₁ phase was observed after ERG gene silencing. In conclusion, these bioinformatics analyses provide novel insights for TMPRSS2:ERG fusion gene study in prostate cancer. Target inhibition of ERG expression could significantly cause cell growth arrest in prostate cancer cells, which could be a potentially valuable target for prostate cancer treatment. However, the precise mechanism of these results remains unclear; therefore, further studies are required.

Risk Stratification of Newly Diagnosed Prostate Cancer with Genomic Platforms

INTRODUCTION

Interest in novel risk stratification tools for men with newly diagnosed prostate cancer has flourished, aiming to offer increasingly accurate predictions of future disease behavior to ultimately better guide clinical management. We highlight the use of genomic platforms attempting to refine clinical decisions at the point of initial diagnosis.

METHODS

In the context of a benchmark standard of clinical risk stratification tools we reviewed the role of genomic tests, including individual gene expression assays, as well as a growing number of tissue based expression tests assessing multiple gene panels, to improve predictions at initial diagnosis.

RESULTS

The role of single gene status including TMPRSS2:ERG fusion and PTEN expression has been investigated among men with newly diagnosed prostate cancer. Gene expression profiles incorporating panels of genes associated with prostate cancer outcome have received external validation and have commercial application in assays that incorporate baseline clinical risk to offer predictions of immediate pathological and downstream disease end points. Comparisons of gene signatures have offered insights into relative predictive performance in archival tissue. However, to date no studies appear to directly support a single genomic assay offering superior clinical usefulness for decision making at the time of diagnosis.

CONCLUSIONS

Risk stratification tools incorporating genomic analysis of prostate cancer have been developed which seek to improve the accuracy of initial predictions. Further study is warranted to define the additive clinical benefit associated with their use if implemented broadly.

The association between SPINK1 and clinical outcomes in patients with prostate cancer: a systematic review and meta-analysis

Evidence of the prognostic role of serine peptidase inhibitor Kazal type 1 (SPINK1) in prostate cancer (PCa) is controversial. The aim of this study was, therefore, to evaluate the association between SPINK1 and clinical outcomes in PCa. Searches were made of PubMed, Medline, Embase, and the China Biology Medicine disc (CBMdisc) up to January 2017. The Newcastle–Ottawa Scale was used to assess the risk of bias of included studies. RevMan software was used to perform meta-analysis, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) method was employed for assessing the quality of the evidence. Ten studies with 17,161 patients were included in the analysis. Random-effect models were adopted for all outcomes with significant heterogeneities. In patients treated with radical prostatectomy, SPINK1 was associated with biochemical recurrence (BCR) (hazard ratio [HR] =1.41, 95% confidence interval [CI]: 1.01–1.97; P=0.04), but not PCa-specific mortality (HR =0.93, 95% CI: 0.33–2.57; P=0.88), and overall survival (OS) (HR =0.89, 95% CI: 0.58–1.35; P=0.57). In metastatic PCa, SPINK1 was significantly associated with castration-resistant PCa-free survival (HR =3.87, 95% CI: 1.87–8.00; P=0.0003) and OS (HR =2.59, 95% CI: 1.16–5.78; P=0.02). However, the quality of the evidence was very low for all study outcome measures. In conclusion, although SPINK1 was not a predictor of PCa mortality or OS among patients who underwent radical prostatectomy, it may have prognostic value in metastatic PCa.

Prostate cancer in Jordanian-Arab population: ERG status and relationship with clinicopathologic characteristics

TMPRSS2/ERG fusion was found to be the most common genetic event in prostate adenocarcinoma. There is a strong correlation between the fusion and ERG-positive immunostaining. Many studies showed racial variation in ERG expression in prostate cancer patients. There is no data however on the rate of ERG-positive cancer in Jordanian or Arab population. We evaluated the frequency and the significance of ERG fusion in Jordanian-Arab population using immunohistochemistry for ERG. The cohort included 193 prostate cancer specimens: 109 needle core biopsies, 45 radical prostatectomies, 37 transurethral resections of prostate, and 2 enucleation specimens. We found ERG reactivity in 64 (33.2%) of evaluated cases. The observed ERG frequency in the Jordanian-Arab population is lower than the one documented in North America, but it is higher than in Asian patient cohorts. The ERG positivity was significantly associated with lower baseline prostate-specific antigen but was unrelated to patient age, Gleason Score, or the novel Gleason Grade Groups. In the 45 prostatectomy cases, ERG did not correlate with the pathologic stage, margin, nodal status, and the biochemical recurrence, and it did not appear to represent an important prognosticator.

Insulin-like growth factor 1 receptor affects the survival of primary prostate cancer patients depending on TMPRSS2-ERG status

BACKGROUND

Prostate cancer (PCa) is characterized by clinical and biological heterogeneity and has differential outcomes and mortality rates. Therefore, it is necessary to identify molecular alterations to define new therapeutic strategies based on the risk of progression. In this study, the prognostic relevance of the insulin-like growth factor (IGF) system was examined in molecular subtypes defined by TMPRSS2-ERG (T2E) gene fusion within a series of patients with primary localized PCa.

METHODS

A cohort of 270 formalin-fixed and paraffin-embedded (FFPE) primary PCa samples from patients with more than 5 years' follow-up was collected. IGF-1R, IGF-1, IGFBP-3 and INSR expression was analyzed using quantitative RT-PCR. The T2E status and immunohistochemical ERG findings were considered in the analyses. The association with both biochemical and clinical progression-free survival (BPFS and PFS, respectively) was evaluated for the different molecular subtypes using the Kaplan-Meier proportional risk log-rank test and the Cox proportional hazards model.

RESULTS

An association between IGF-1R overexpression and better BPFS was found in T2E-negative patients (35.3% BPFS, p-value = 0.016). Multivariate analysis demonstrated that IGF-1R expression constitutes an independent variable in T2E-negative patients [HR: 0.41. CI 95% (0.2-0.82), p = 0.013]. These data were confirmed using immunohistochemistry of ERG as subrogate of T2E. High IGF-1 expression correlated with prolonged BPFS and PFS independent of the T2E status.

CONCLUSIONS

IGF-1R, a reported target of T2E, constitutes an independent factor for good prognosis in T2E-negative PCa. Quantitative evaluation of IGF-1/IGF-1R expression combined with molecular assessment of T2E status or ERG protein expression represents a useful marker for tumor progression in localized PCa.

Comprehensive Determination of Prostate Tumor ETS Gene Status in Clinical Samples Using the CLIA Decipher Assay

ETS family gene fusions are common in prostate cancer and molecularly define a tumor subset. ERG is the most commonly rearranged, leading to its overexpression, followed by ETV1, ETV4, and ETV5, and these alterations are generally mutually exclusive. We validated the Decipher prostate cancer assay to detect ETS alterations in a Clinical Laboratory Improvement Amendments-accredited laboratory. Benchmarking against ERG immunohistochemistry and ETV1/4/5 RNA in situ hybridization, we examined the accuracy, precision, and reproducibility of gene expression ETS models using formalin-fixed, paraffin-embedded samples. The m-ERG model achieved an area under curve of 95%, with 93% sensitivity and 98% specificity to predict ERG immunohistochemistry status. The m-ETV1, -ETV4, and -ETV5 models achieved areas under curve of 98%, 88%, and 99%, respectively. The models had 100% robustness for ETS status, and scores were highly correlated across sample replicates. Models predicted 41.5% of a prospective radical prostatectomy cohort (n = 4036) to be ERG+, 6.3% ETV1+, 1% ETV4+, and 0.4% ETV5+. Of prostate tumor biopsy samples (n = 509), 41.2% were ERG+, 8.6% ETV1+, 0.4% ETV4+, and none ETV5+. Higher Decipher risk status tumors were more likely to be ETS+ (ERG or ETV1/4/5) in the radical prostatectomy and the biopsy cohorts (P < 0.05). These results support the utility of microarray-based ETS status prediction models for molecular classification of prostate tumors.

Identification and evaluation of clinically significant prostate cancer: a step towards personalized diagnosis

PURPOSE OF REVIEW

Prostate cancer (PCa) diagnostics are evolving rapidly. The quest to differentiate 'clinically significant' from 'clinically insignificant' disease has gathered momentum, leading to substantial change in traditional diagnostic approaches. Herein, we review the relevant information on currently available biomarkers and assess their ability to help physicians and patients in making a shared and personalized decision based on their individual risk of harbouring clinically significant disease.

RECENT FINDINGS

Serum, urine, tissue and imaging biomarkers have been evaluated to improve the identification of clinically significant disease, and this international effort has yielded promising, but not always consistent results. Changes in MRI technology have realized a quantum change, and this facility is now becoming more widely incorporated into diagnostic and disease risk-stratification protocols. However, standardization and further validation is required.

SUMMARY

Acceptance and widespread adoption of serum, urine and genetic markers is awaited, but novel and promising techniques alone and in combination have emerged. With validation and further focus, these may be adopted more widely.

Circulating Antioxidant Levels and Risk of Prostate Cancer by TMPRSS2:ERG

BACKGROUND

Few studies have considered etiological differences across molecular subtypes of prostate cancer, despite potential to improve opportunities for precision prevention of a disease for which modifiable risk factors have remained elusive. Factors that lead to DNA double-strand breaks, such as oxidative stress, may promote the formation of the TMPRSS2:ERG gene fusion in prostate cancer. We tested the hypothesis that increasing levels of pre-diagnostic circulating antioxidants, which may reduce oxidative stress, are associated with lower risk of developing TMPRSS2:ERG positive prostate cancer.

METHODS

We conducted a nested case-control study, including 370 cases and 2,470 controls, to evaluate associations between pre-diagnostic α- and β-carotene, α- and γ-tocopherol, β-cryptoxanthin, lutein, lycopene, retinol, and selenium with the risk of prostate cancer by ERG protein expression status (a marker of TMPRSS2:ERG). Multivariable unconditional polytomous logistic regression was used to calculate odds ratios and 95% confidence intervals.

RESULTS

We did not find any of the antioxidants to be significantly associated with the risk of prostate cancer according to ERG status.

CONCLUSIONS

The results do not support the hypothesis that circulating pre-diagnostic antioxidant levels protect against developing TMPRSS2:ERG positive prostate cancer. Additional studies are needed to explore mechanisms for the development of TMPRSS2:ERG positive disease. Prostate 77: 647-653, 2017. © 2017 Wiley Periodicals, Inc.

Two-Stage Biomarker Protocols for Improving the Precision of Early Detection of Prostate Cancer

Background. New cancer biomarkers are being discovered at a rapid pace; however, these tests vary in their predictive performance characteristics, and it is unclear how best to use them. Methods. We investigated 2-stage biomarker-based screening strategies in the context of prostate cancer using a partially observable Markov model to simulate patients’ progression through prostate cancer states to mortality from prostate cancer or other causes. Patients were screened every 2 years from ages 55 to 69. If the patient’s serum prostate-specific antigen (PSA) was over a specified threshold in the first stage, a second stage biomarker test was administered. We evaluated design characteristics for these 2-stage strategies using 7 newly discovered biomarkers as examples. Monte Carlo simulation was used to estimate the number of screening biopsies, prostate cancer deaths, and quality-adjusted life-years (QALYs) per 1000 men. Results. The all-cancer biomarkers significantly underperformed the high-grade cancer biomarkers in terms of QALYs. The screening strategy that used a PSA threshold of 2 ng/mL and a second biomarker test with high-grade sensitivity and specificity of 0.86 and 0.62, respectively, maximized QALYs. This strategy resulted in a prostate cancer death rate within 1% of using PSA alone with a threshold of 2 ng/mL, while reducing the number of biopsies by 20%. Sensitivity analysis suggests that the results are robust with respect to variation in model parameters. Conclusions. Two-stage biomarker screening strategies using new biomarkers with risk thresholds optimized for high-grade cancer detection may increase quality-adjusted survival and reduce unnecessary biopsies.

Dishevelled segment polarity protein 3 (DVL3): a novel and easily applicable recurrence predictor in localised prostate adenocarcinoma

OBJECTIVE

To identify new biomarkers for biochemical recurrence (BCR) of prostate adenocarcinoma.

PATIENTS AND METHODS

Clinical information of 500 patients with prostate adenocarcinoma and their 152 RNA-sequencing and protein-array data from The Cancer Genome Atlas (TCGA) were separated into a discovery set and a validation set. Each dataset was analysed according to the Gleason grade groups reflecting BCR. The results obtained from the analysis using TCGA dataset were confirmed by immunohistochemistry analyses of a confirmation cohort composed of 395 patients with localised prostate adenocarcinoma.

RESULTS

TCGA discovery set was subgrouped into lower- and higher-risk groups for recurrence-free survival (RFS) (P < 0.001). Cyclin B1 (CCNB1), dishevelled segment polarity protein 3 (DVL3), paxillin (PXN), RAF1, transferrin, X-ray repair cross complementing 5 (XRCC5) and BIM had lower expression in the lower-risk group than that in the higher-risk group (all, P < 0.05). In TCGA validation set, CCNB1, DVL3, transferrin, XRCC5 and BIM were also differently expressed between the two groups. Immunohistochemically, DVL3 positivity was associated with high prostate-specific antigen (PSA) levels, resection margin involvement, and BCR (all, P < 0.05). A high Gleason score indicated a marginal relationship (P = 0.055). BIM positivity was related to high PSA levels, lymphovascular invasion, and BCR (all, P < 0.05). Both DVL3 positivity (P = 0.010) and BIM positivity (P = 0.024) were associated with shorter RFS, but statistical significance was lost when the multivariate Cox regression model included all patients. In the lower-risk group, the multivariate Cox model confirmed that DVL3 was an independent predictor for poor RFS (hazard ratio 1.80, P = 0.040), and the concordance index (C-index) was 0.805.

CONCLUSIONS

DVL3 and BIM were expressed in patients with a higher risk of BCR. DVL3 may be a novel and easily applicable recurrence predictor of localised prostate adenocarcinoma.

The ABC model of prostate cancer: A conceptual framework for the design and interpretation of prognostic studies

There has been limited success in identifying prognostic biomarkers in prostate cancer. A partial explanation may be that insufficient emphasis has been put on clearly defining what type of marker or patient category a biomarker study aims to identify and how different cohort characteristics affect the ability to identify such a marker. In this article, the authors put forth the ABC model of prostate cancer, which defines 3 groups of patients with localized disease that an investigator may seek to identify: patients who, within a given time frame, will not develop metastases even if untreated (category A), will not develop metastases because of radical treatment (category B), or will develop metastases despite radical treatment (category C). The authors demonstrate that follow-up time and prostate-specific antigen screening intensity influence the prevalence of patients in categories A, B, and C in a study cohort, and that prognostic markers must be tested in both treated and untreated cohorts to accurately distinguish the 3 groups. The authors suggest that more emphasis should be put on considering these factors when planning, conducting, and interpreting the results from prostate cancer biomarker studies, and propose the ABC model as a framework to aid in that process. Cancer 2017;123:1490-1496. © 2017 American Cancer Society.

Prostate Cancer Genetics: Variation by Race, Ethnicity, and Geography

Prostate cancer rates vary substantially by race, ethnicity, and geography. These disparities can be explained by variation in access to screening and treatment, variation in exposure to prostate cancer risk factors, and variation in the underlying biology of prostate carcinogenesis (including genomic propensity of some groups to develop biologically aggressive disease). It is clear that access to screening and access to treatment are critical influencing factors of prostate cancer rates; yet, even among geographically diverse populations with similar access to care (eg, low- and medium-income countries), African descent men have higher prostate cancer rates and poorer prognosis. To date, the proportion of prostate cancer that can be explained by environmental exposures is small, and the effect of these factors across different racial, ethnic, or geographical populations is poorly understood. In contrast, prostate cancer has one of the highest heritabilities of all major cancers. Numerous genetic susceptibility markers have been identified from family-based studies, candidate gene association studies, and genome-wide association studies. Some prostate cancer loci, including the risk loci found at chromosome 8q24, have consistent effects in all groups studied to date. However, replication of many susceptibility loci across race, ethnicity, and geography remains limited, and additional studies in certain populations (particularly in men of African descent) are needed to better understand the underlying genetic basis of prostate cancer.

The Use of Biomarkers in Prostate Cancer Screening and Treatment

Prostate cancer screening and diagnosis has been guided by prostate-specific antigen levels for the past 25 years, but with the most recent US Preventive Services Task Force screening recommendations, as well as concerns regarding overdiagnosis and overtreatment, a new wave of prostate cancer biomarkers has recently emerged. These assays allow the testing of urine, serum, or prostate tissue for molecular signs of prostate cancer, and provide information regarding both diagnosis and prognosis. In this review, we discuss 12 commercially available biomarker assays approved for the diagnosis and treatment of prostate cancer. The results of clinical validation studies and clinical decision-making studies are presented. This information is designed to assist urologists in making clinical decisions with respect to ordering and interpreting these tests for different patients. There are numerous fluid and biopsy-based genomic tests available for prostate cancer patients that provide the physician and patient with different information about risk of future disease and treatment outcomes. It is important that providers be able to recommend the appropriate test for each individual patient; this decision is based on tissue availability and prognostic information desired. Future studies will continue to emphasize the important role of genomic biomarkers in making individualized treatment decisions for prostate cancer patients.