Nikhil Sapre

Tracking the origins and drivers of subclonal metastatic expansion in prostate cancer

Tumour heterogeneity in primary prostate cancer is a well-established phenomenon. However, how the subclonal diversity of tumours changes during metastasis and progression to lethality is poorly understood. Here we reveal the precise direction of metastatic spread across four lethal prostate cancer patients using whole-genome and ultra-deep targeted sequencing of longitudinally collected primary and metastatic tumours. We find one case of metastatic spread to the surgical bed causing local recurrence, and another case of cross-metastatic site seeding combining with dynamic remoulding of subclonal mixtures in response to therapy. By ultra-deep sequencing end-stage blood, we detect both metastatic and primary tumour clones, even years after removal of the prostate. Analysis of mutations associated with metastasis reveals an enrichment of TP53 mutations, and additional sequencing of metastases from 19 patients demonstrates that acquisition of TP53 mutations is linked with the expansion of subclones with metastatic potential which we can detect in the blood.

Prostate tumour volume is an independent predictor of early biochemical recurrence in a high risk radical prostatectomy subgroup

Aims: To assess if accurately determined tumour volume variables could serve as independent predictors of early biochemical recurrence in high risk prostate cancer patients who underwent radical prostatectomy. Methods: Tumour volume variables were calculated by digital planimetry in 269 prostatectomy specimens of patients with high risk prostate cancer. The associations to biochemical progression of tumour volume and clinicopathological variables, including age, pre-operative prostate specific antigen (PSA) levels, final Gleason score, pathological T stage, and surgical margins, were examined using univariate and multivariate Cox proportional hazards analyses. Results: Median tumour volume was 3.7 ml [interquartile range (IQR) 2.1–6.1 mL] and median follow-up time was 12 months (IQR 6–24 months). Biochemical recurrence occurred in 64 men (24%) during this period, with a median time to recurrence of 7.5 months (IQR 3.0–15.5 months). On univariate analysis all of the tumour volume variables were strongly correlated with the clinicopathological variables, as well as biochemical recurrence (p < 0.001). On multivariate analysis, we found that tumour volume variables served as independent predictors of PSA progression whilst other routinely reported pathological variables did not. Conclusion: Accurately assessing tumour volume in the high risk setting may aid in identifying patients at greatest risk of developing early biochemical recurrence and most in need of adjuvant therapy.

A urinary microRNA signature can predict the presence of bladder urothelial carcinoma in patients undergoing surveillance.

Background:The objective of this study was to determine whether microRNA (miRNA) profiling of urine could identify the presence of urothelial carcinoma of the bladder (UCB) and to compare its performance characteristics to that of cystoscopy.Methods:In the discovery cohort we screened 81 patients, which included 21 benign controls, 30 non-recurrers and 30 patients with active cancer (recurrers), using a panel of 12 miRNAs. Data analysis was performed using a machine learning approach of a Support Vector Machine classifier with a Student’s t-test feature selection procedure. This was trained using a three-fold cross validation approach and performance was measured using the area under the receiver operator characteristic curve (AUC). The miRNA signature was validated in an independent cohort of a further 50 patients.Results:The best predictor to distinguish patients with UCB from non-recurrers was achieved using a combination of six miRNAs (AUC=0.85). This validated in an independent cohort (AUC=0.74) and detected UCB with a high sensitivity (88%) and sufficient specificity (48%) with all significant cancers identified. The performance of the classifier was best in detecting clinically significant disease such as presence of T1 Stage disease (AUC=0.92) and high-volume disease (AUC=0.81). Cystoscopy rates in the validation cohort would have been reduced by 30%.Conclusions:Urinary profiling using this panel of miRNAs shows promise for detection of tumour recurrence in the surveillance of UCB. Such a panel may be useful in reducing the morbidity and costs associated with cystoscopic surveillance, and now merits prospective evaluation.

Gene-based urinary biomarkers for bladder cancer: An unfulfilled promise?

OBJECTIVE Noninvasive biomarkers are used routinely in the clinical management of several cancers but bladder cancer detection and surveillance remains dependent on invasive procedures such as cystoscopy. No validated biomarker currently exists in routine clinical practice other than cytology. Gene-based testing has shown great promise for biomarker profiling and this review addresses the current state of biomarker research in bladder cancer. MATERIALS AND METHODS A comprehensive review of all published literature on urinary biomarkers from 1970 - 2012 was conducted in PubMed. Keywords used alone or in combination were bladder cancer, diagnosis, surveillance, urinary biomarker, molecular biomarkers, methylation, gene expression, single nucleotide polymorphism and microRNA. The cited references of the manuscripts included in the review were also screened. RESULTS We have reviewed various strategies currently used for gene-based biomarker profiling of bladder cancer. We have comprehensively summarized the performance of several biomarkers in the diagnosis and surveillance of bladder cancer. Finally we have identified biomarkers that have shown potential and now deserve the opportunity to be validated in the clinical setting. CONCLUSION Several gene-based urinary biomarkers have demonstrated promise in initial studies, which now need to be rigorously validated in the clinical setting for them to be translated into clinically useful tests in diagnosis, surveillance or risk-stratification of bladder cancer.

Curated microRNAs in urine and blood fail to validate as predictive biomarkers for high-risk prostate cancer.

Purpose The purpose of this study was to determine if microRNA profiling of urine and plasma at radical prostatectomy can distinguish potentially lethal from indolent prostate cancer. Materials and Methods A panel of microRNAs was profiled in the plasma of 70 patients and the urine of 33 patients collected prior to radical prostatectomy. Expression of microRNAs was correlated to the clinical endpoints at a follow-up time of 3.9 years to identify microRNAs that may predict clinical response after radical prostatectomy. A machine learning approach was applied to test the predictive ability of all microRNAs profiled in urine, plasma, and a combination of both, and global performance assessed using the area under the receiver operator characteristic curve (AUC). Validation of urinary expression of miRNAs was performed on a further independent cohort of 36 patients. Results The best predictor in plasma using eight miRs yielded only moderate predictive performance (AUC = 0.62). The best predictor of high-risk disease was achieved using miR-16, miR-21 and miR-222 measured in urine (AUC = 0.75). This combination of three microRNAs in urine was a better predictor of high-risk disease than any individual microRNA. Using a different methodology we found that this set of miRNAs was unable to predict high-volume, high-grade disease. Conclusions Our initial findings suggested that plasma and urinary profiling of microRNAs at radical prostatectomy may allow prognostication of prostate cancer behaviour. However we found that the microRNA expression signature failed to validate in an independent cohort of patients using a different platform for PCR. This highlights the need for independent validation patient cohorts and suggests that urinary microRNA signatures at radical prostatectomy may not be a robust way to predict the course of clinical disease after definitive treatment for prostate cancer.

Molecular biomarkers for predicting outcomes in urothelial carcinoma of the bladder

Summary Molecular biomarkers are used routinely in the clinical management of several tumours such as prostate, colon, ovarian and pancreatic cancer but management decisions in bladder cancer remain dependent on clinical and pathological criteria, which are limited in their ability to predict outcomes. Molecular markers are urgently needed in detection, surveillance and prognostication of bladder cancer as well as to predict treatment response to intravesical and systemic therapies. Advances in cancer genomics and platforms for biomarker profiling have led to a plethora of biomarkers, which must now be rigorously validated in the clinical setting. Pre-clinical and clinical studies exploring the role of emerging targeted therapies to risk stratify and reduce cancer progression are also needed.

Nurse-led flexible cystoscopy in Australia: initial experience and early results.

Whats known on the subject? and What does the study add?

Modulating the immune response to Bacillus Calmette-Guerin (BCG): a novel way to increase the immunotherapeutic effect of BCG for treatment of bladder cancer?

The development and progression of cancer is critically dependent upon a relative immunodeficiency of the body in initiating an antitumour response. BCG, a live attenuated form of Mycobacterium bovis, is commonly used for the treatment of high grade non-muscle-invasive transitional cell carcinoma of the bladder and carcinoma in situ, to reduce the risk of recurrence and progression [1]. Without BCG, the body only activates the immune system non-specifically and weakly in an effort to clear bladder cancer cells. The precise mechanism of action of BCG is unknown, but current research shows that it stimulates both an inflammatory tumour response as well as an adaptive (specific) immune response to clear residual bladder cancer cells [2]. A proposed model for the mechanism of action of BCG is shown in Fig. 1. The innate (non-specific) immune response acts against microbes to keep the urinary tract sterile [3]. Some of the effectors of this innate response to microorganisms are antimicrobial peptides such as β-defensins [4]. In the accompanying publication, Kim et al. [5] show that bladder cancer cells produce human β-defensin-2 (HBD2) when they are infected with BCG, to defend them against BCG and thus may play a role in the immunotherapeutic response of BCG.

Re-evaluating the biological significance of seminal vesicle invasion (SVI) in locally advanced prostate cancer

•  To examine the impact of seminal vesicle invasion (SVI) in patients with locally advanced (pT3) prostate cancer on clinical outcome. •  To explore the clinical association of SVI with metastatic disease. •  To distinguish between the possibilities that either seminal vesicles possess their own biological significance and represent a privileged staging site for systemic tumour cell dissemination, or that their invasion is a surrogate marker for an aggressive large‐volume poorly differentiated cancer.

Management of local recurrences in the irradiated bladder: a systematic review.

•  To review and report the management and outcomes of patients with recurrence of bladder cancer (BC) who initially had complete response to bladder conservation therapy.