The predictive value of ERG protein expression for development of castration-resistant prostate cancer in hormone-naïve advanced prostate cancer treated with primary androgen deprivation therapy

Clinical implication of prognostic and predictive biomarkers for castration-resistant prostate cancer: a systematic review

Background

Diagnosis of metastatic castrate resistant prostate cancer (mCRPC) with current biomarkers is difficult and often results in unnecessary invasive procedures as well as over-diagnosis and over-treatment. There are a number of prognostic biomarkers for CRPC, but there are no validated predictive biomarkers to guide in clinical decision-making. Specific biomarkers are needed that enable to understand the natural history and complex biology of this heterogeneous malignancy, identify early response to treatment outcomes and to identify the population of men most likely to benefit from the treatment. In this systematic review, we discuss the existing literature for the role of biomarkers in CRPC and how they aid in the prognosis, treatment selection and survival outcomes.

Methods

We performed a literature search on PubMed and EMBASE databases from January 2015 through February 2020 in accordance to Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. Articles were assessed to identify relevant observational studies and randomized controlled trials regarding biomarkers which aid in identifying progression to mCRPC as well as predictive biomarkers which help in treatment selection.

Results

We identified 3640 number of hits of which 58 articles were found to be relevant. Here we addressed biomarkers in the context of prognosis, prediction and patient selection of therapy. These biomarkers were found to be effective as prognostic or predictive factors under variety of conditions. The higher levels for all these biomarkers were associated with shorter median OS and sometimes PFS. Lower amounts of biomarkers in serum or urine were associated with prolonged survival outcomes, longer time to CRPC development or CRPC progression and longer median follow-up irrespective of any therapy.

Conclusion

We observed that the biomarkers included in our study predicted clinically relevant survival outcomes and treatment exposure. Though the current biomarkers are prognostic when measured prior to initiating treatment, not all are validated as predictive markers in post treatment setting. A greater understanding of biomarkers in CRPC is need of the hour for development of more personalized approach to maximize benefit and minimize harm in men with CRPC.

AZGP1 Protein Expression in Hormone-Naïve Advanced Prostate Cancer Treated with Primary Androgen Deprivation Therapy

Biomarkers for predicting the risk of castration-resistant prostate cancer (CRPC) in men treated with primary androgen deprivation therapy (ADT) are lacking. We investigated whether Zinc-alpha 2 glycoprotein (AZGP1) expression in the diagnostic biopsies of men with hormone-naïve prostate cancer (PCa) undergoing primary ADT was predictive of the development of CRPC and PCa-specific mortality. The study included 191 patients who commenced ADT from 2000 to 2011. The AZGP1 expression was evaluated using immunohistochemistry and scored as high or low expression. The risks of CRPC and PCa-specific mortality were analyzed using stratified cumulative incidences and a cause-specific COX regression analysis for competing risk assessment. The median follow-up time was 9.8 (IQR: 6.1–12.7) years. In total, 94 and 97 patients presented with low and high AZGP1 expression, respectively. A low AZGP1 expression was found to be associated with a shorter time to CRPC when compared to patients with a high AZGP1 expression (HR: 1.5; 95% CI: 1.0–2.1; p = 0.03). However, the multivariable analysis demonstrated no added benefit by adding the AZGP1 expression to prediction models for CRPC. No differences for PCa-specific mortality between the AZGP1 groups were observed. In conclusion, a low AZGP1 expression was associated with a shorter time to CRPC for PCa patients treated with first-line ADT but did not add any predictive information besides well-established clinicopathological variables.

Extracellular vesicles in urological malignancies: an update

Extracellular vesicles (EVs) have an essential functional role in local tumour progression, metastatic spread and the emergence of drug resistance in bladder, kidney and prostate cancer. Thus, EVs could be diagnostic, prognostic and predictive biomarkers for these malignancies. Virtually all biomolecules (including DNA, mRNA, microRNA, long non-coding RNA, proteins and lipids) packaged into EVs have been tested as biomarkers in blood and urine samples. The results are very heterogeneous, but promising biomarker candidates have been identified. Differing methods of EV isolation, characterization and analysis of their content have been used owing to a lack of international consensus; hence, comparing study results is challenging. Furthermore, validation of potential biomarkers in independent cohorts or prospective trials has rarely been performed. Future efforts to establish EV-derived biomarkers need to adequately address these points. In addition, emerging technologies such as mass spectroscopy and chip-based approaches can identify surface markers specific for cancer-associated EVs and will enable specific separation from blood and urine EVs, which probably will improve their performance as biomarkers. Moreover, EVs could be harnessed as therapeutic drug delivery vehicles for precise and effective anticancer therapy.

ETS-related gene (ERG) expression as a predictor of oncological outcomes in patients with high-grade prostate cancer treated with primary androgen deprivation therapy: a cohort study

OBJECTIVES

To determine whether ETS-related gene (ERG) expression can be used as a biomarker to predict biochemical recurrence and prostate cancer-specific death in patients with high Gleason grade prostate cancer treated with androgen deprivation therapy (ADT) as monotherapy.

METHODS

A multicentre retrospective cohort study identifying 149 patients treated with primary ADT for metastatic or non-metastatic prostate cancer with Gleason score 8-10 between 1999 and 2006. Patients planned for adjuvant radiotherapy at diagnosis were excluded. Age at diagnosis, ethnicity, prostate-specific antigen and Charlson-comorbidity score were recorded. Prostatic tissue acquired at biopsy or transurethral resection surgery was assessed for immunohistochemical expression of ERG. Failure of ADT defined as prostate specific antigen nadir +2. Vital status and death certification data determined using the UK National Cancer Registry. Primary outcome measures were overall survival (OS) and prostate cancer specific survival (CSS). Secondary outcome was biochemical recurrence-free survival (BRFS).

RESULTS

The median OS of our cohort was 60.2 months (CI 52.0 to 68.3). ERG expression observed in 51/149 cases (34%). Multivariate Cox proportional hazards analysis showed no significant association between ERG expression and OS (p=0.41), CSS (p=0.92) and BRFS (p=0.31). Cox regression analysis showed Gleason score (p=0.003) and metastatic status (p<1×10^-5) to be the only significant predictors of prostate CSS.

CONCLUSIONS

No significant association was found between ERG status and any of our outcome measures. Despite a limited sample size, our results suggest that ERG does not appear to be a useful biomarker in predicting response to ADT in patients with high risk prostate cancer.

Cytoreductive prostatectomy in metastatic prostate cancer: a systematic review

The impact of cytoreductive radical prostatectomy on oncological outcome in patients with prostate cancer and limited number of bone metastases is unclear. Data from cancer registries, multi-institutional databases and a single institutional case-control study indicate a possible benefit of combined cytoreduction and hormonal therapy compared to hormonal therapy alone. However, the results may be biased by a number of factors. The evidence from studies on cytoreductive prostatectomy is reviewed.

Does Cytoreductive Prostatectomy Really Have an Impact on Prognosis in Prostate Cancer Patients with Low-volume Bone Metastasis? Results from a Prospective Case-Control Study

The impact of cytoreductive radical prostatectomy (CRP) on oncological outcomes in patients with prostate cancer (PCa) and distant metastases has been demonstrated by retrospective data with their potential selection bias. Using prospective institutional data, we compared the outcomes between 43 PCa patients with low-volume bone metastases (1-3 lesions) undergoing CRP (median follow-up 32.7 mo) and 40 patients receiving best systemic therapy (BST; median follow-up 82.2 mo). The inclusion criteria for both cohorts were identical. So far, no significant difference in castration resistant-free survival (p=0.92) or overall survival (p=0.25) has been detected. Compared to recent reports, the outcomes for our control group are more favorable, indicating a potential selection bias in the previous retrospective studies. Therefore, the unclear oncological effect has to be weighed against the potential risks of CRP. However, patients benefit from a significant reduction in locoregional complications (7.0% vs 35%; p<0.01) when undergoing CRP.

PATIENT SUMMARY

In this study we analyzed the impact of surgery in patients with prostate cancer and bone metastases. Using prospective data, we could not show a significant benefit of surgery on survival, but the rate of locoregional complications was lower. Therefore, patients should be treated within prospective trials evaluating the role of cytoreductive prostatectomy in low-volume, bone metastatic prostate cancer.

The ETS family of oncogenic transcription factors in solid tumours

Findings over the past decade have identified aberrant activation of the ETS transcription factor family throughout all stages of tumorigenesis. Specifically in solid tumours, gene rearrangement and amplification, feed-forward growth factor signalling loops, formation of gain-of-function co-regulatory complexes and novel cis-acting mutations in ETS target gene promoters can result in increased ETS activity. In turn, pro-oncogenic ETS signalling enhances tumorigenesis through a broad mechanistic toolbox that includes lineage specification and self-renewal, DNA damage and genome instability, epigenetics and metabolism. This Review discusses these different mechanisms of ETS activation and subsequent oncogenic implications, as well as the clinical utility of ETS factors.

Tools for Predicting Clinical and Patient-reported Outcomes in Prostate Cancer Patients Undergoing Androgen Deprivation Therapy: A Systematic Review of Prognostic Accuracy and Validity

Androgen deprivation therapy (ADT) can result in a range of adverse symptoms that reduce patients' quality of life. Careful patient counseling on the likely clinical outcomes and adverse effects is therefore vital. The present systematic review was undertaken to identify and characterize all the tools used for the prediction of clinical and patient-reported outcome measures (PROMs) in patients with prostate cancer undergoing ADT. PubMed and EMBASE were systematically searched from 2007 to 2016. Search terms related to the inclusion criteria were: prostate cancer, clinical outcomes, PROMs, ADT, and prognosis. Titles and abstracts were reviewed to find relevant studies, which were advanced to full-text review. The reference lists were screened for additional studies. The Centre for Evidence Based Medicine critical appraisal of prognostic studies tool was applied. The search strategy identified 8755 studies. Of the 8755 studies, 22 on clinical outcomes were identified. However, no studies of PROMs were found. Nine tools could be used to predict clinical outcomes in treatment-naive patients and 10 in patients with recurrence. The Japan Cancer of the Prostate Risk Assessment (J-CAPRA) nomogram was the best performing and validated tool for the prediction of clinical outcomes in treatment-naive patients, and the Chi and Shamash prognostic indexes have been validated for use in patients with castration-resistant disease in different clinical contexts. Using the J-CAPRA nomogram should help clinicians deliver accurate, evidence-based counseling to patients undergoing primary ADT. A strong need exists for primary studies that derive and validate tools for the prediction of PROMs in patients undergoing ADT under any circumstance because these are currently absent from the literature.

Improved survival for patients with de novo metastatic prostate cancer in the last 20 years

INTRODUCTION

During recent years, several new life-prolonging therapeutic options have been introduced for patients with metastatic prostate cancer (mPCa). The aim of the present study was to evaluate the changes in the survival of patients diagnosed with mPCa prior to and in the early period of the implementation of these new agents.

PATIENTS AND METHODS

The study population consisted of 207 men diagnosed in 1997 and 316 men diagnosed in the period 2007-2013 with de novo mPCa and managed with initial endocrine therapy. Men were followed for overall survival and PCa-specific survival.

RESULTS

At the time of diagnosis, men diagnosed in the period 2007-2013 had less co-morbidity, lower prostrate-specific antigen levels and lower clinical tumour categories than men diagnosed in 1997. A significantly higher proportion of men diagnosed in 1997 were managed with surgical castration (57% versus 9%). Only one patient diagnosed in 1997 received second-line therapy compared with 81 men (26%) diagnosed in the period 2007-2013. The median overall survival was significantly longer for men diagnosed between 2007 and 2013 compared with men diagnosed in 1997 (39.4 months versus 24.2 months, p < 0.0001). Likewise, the cumulative incidence of PCa-specific death was higher among men diagnosed in 1997 compared with men diagnosed between 2007 and 2013, with 5-year cumulative incidences of 72% and 47%, respectively (p < 0.0001).

CONCLUSION

Survival in men diagnosed with metastatic PCa has improved significantly over time. The improved survival can in part be explained by lead-time bias, but also by the introduction of new life-prolonging treatments.

Factors predicting progression to castrate-resistant prostate cancer in patients with advanced prostate cancer receiving long-term androgen-deprivation therapy

OBJECTIVES

To assess time to progression to castrate-resistant prostate cancer (CRPC) and factors influencing longer-term outcomes in patients receiving androgen-deprivation therapy (ADT) in an extension to the Triptocare study (NCT01020448). This is pertinent as the Triptocare study did not show that urinary prostate cancer antigen-3 (PCA3) score was a reliable marker of cancer stage in advanced prostate cancer and was not useful for assessing response 6 months after initiation of ADT with triptorelin 22.5 mg.

PATIENTS AND METHODS

An international, multicentre, non-interventional, observational, longitudinal, prospective study involving patients from the Triptocare study. CRPC status of patients was collected for up to 3 years from ADT initiation. Patient treatment and assessments were at the investigator's discretion. Co-primary endpoints were rate of CRPC at 3 years after initiating ADT and the median time to CRPC. An exploratory endpoint was the association of Triptocare baseline variables (including TMPRSS2-ERG and PCA3 scores) and PCA3 score at Triptocare last value available with CRPC onset.

RESULTS

Of the 325 patients in the Triptocare study safety population, 180 patients were enrolled in the Triptocare LT study (102 received continuous and 78 received intermittent ADT). CRPC rates at 3 years were 24/102 (23.5%) and 6/78 (7.7%) patients in the continuous and intermittent ADT groups, respectively. The median time to CRPC was not reached for either group. PCA3 score status at baseline was the only variable associated with a higher risk of progression to CRPC in both the intermittent and continuous ADT groups; compared with a baseline PCA3 score of ≥35, a PCA3 score below the level of quantification had a hazard ratio (HR) of 20.04 ([95% confidence interval (CI) 2.71-148.34] and a HR of 9.44 [95% CI 2.39-37.27], respectively). Baseline metastatic disease and testosterone level were additionally associated with progression to CRPC in the continuous ADT population (HR 5.20, 95% CI 1.68-16.06 and HR 0.995, 95% CI 0.991-0.999, respectively).

CONCLUSION

In men with locally advanced or metastatic prostate cancer, a PCA3 score of ≥35 at the time of initiating ADT may predict a lower risk of developing CRPC in the following 3 years.