Paul C.M.S. Verhagen

Overexpression of Prostate-Specific TMPRSS2(exon 0)-ERG Fusion Transcripts Corresponds with Favorable Prognosis of Prostate Cancer

Purpose: To gain insight in the mechanism and clinical relevance of TMPRSS2-ERG expression in prostate cancer, we determined the specific characteristics of fusion transcripts starting at TMPRSS2 exon 1 and at a more upstream and less characterized exon 0. Experimental Design: We used quantitative PCR analysis to investigate expression of wild-type TMPRSS2(exon 0) and TMPRSS2(exon 1) and of ERG fusion transcripts. Expression was tested in normal tissue samples, in prostate cancer cell lines and xenografts, and in fresh-frozen clinical prostate cancer samples (primary tumors and recurrences). Expression in clinical samples was correlated with disease progression. Results: TMPRSS2(exon 0) and TMPRSS2(exon 1) transcripts were similarly androgen regulated in prostate cancer cell lines, but the expression levels of TMPRSS2(exon 1) were much higher. Comparison of expression in different tissues showed TMPRSS2(exon 0) expression to be much more prostate specific. In androgen receptor–positive prostate cancer xenografts, TMPRSS2(exon 1) transcripts were expressed at similar levels, but TMPRSS2(exon 0) transcripts were expressed at very variable levels. The same phenomenon was observed for TMPRSS2-ERG fusion transcripts. In clinical prostate cancers, the expression of TMPRSS2(exon 0)-ERG was even more variable. Expression of TMPRSS2(exon 0)-ERG transcripts was detected in 55% (24 of 44) of gene fusion–positive primary tumors but only in 15% (4 of 27) of gene fusion–positive recurrences and at much lower levels. Furthermore, in primary tumors, expression of TMPRSS2(exon 0)-ERG transcripts was an independent predictor of biochemical progression-free survival. Conclusion: The expression of TMPRSS2(exon 0)-ERG fusion transcripts in prostate cancer is associated with a less-aggressive biological behavior. (Clin Cancer Res 2009;15(20):6398–403)

Does Local Treatment of the Prostate in Advanced and/or Lymph Node Metastatic Disease Improve Efficacy of Androgen-Deprivation Therapy? A Systematic Review

CONTEXT Androgen-deprivation therapy (ADT) plays a pivotal role in the management of locally advanced and metastatic prostate cancer (PCa). When and for how long to apply ADT have remained controversial issues. OBJECTIVE To review randomised studies of ADT (orchiectomy or luteinising hormone-releasing hormone analogues) in PCa-both immediate and deferred/adjuvant studies-to elucidate a possible interaction between local treatment and ADT. EVIDENCE ACQUISITION Published randomised studies on ADT in various stages of PCa were included in this review. EVIDENCE SYNTHESIS Studies of immediate versus deferred ADT without local treatment consistently showed only limited benefit for overall survival (OS; hazard ratio [HR]: 0.90; 95% confidence interval [CI], 0.83-0.97) and cancer-specific survival (CSS; HR: 0.79; 95% CI, 0.71-0.89). In contrast, ADT as an adjuvant to radiation therapy in patients with high-risk localised disease or locally advanced disease was associated with substantial OS and CSS benefits. A similar benefit was seen in patients with proven systemic disease (node-positive patients after radical prostatectomy). Overall, the data suggest a clinically important survival benefit (HR for OS: 0.69; 95% CI, 0.61-0.79) when a local treatment has been applied to the primary tumour. Possible mechanisms of this therapeutic effect are discussed. CONCLUSIONS We conclude that an interaction between local treatment and ADT is suggested by this systematic review. In patients with advanced and aggressive disease who are at a high risk to die from PCa and who are treated for their primary tumour with curative intent, immediate and sustained ADT improves OS and CSS significantly. The local therapy in T3 and/or lymph node-positive disease is an essential part of the optimal treatment. However, this intensive treatment is unnecessary in a substantial number of patients with T3 and/or N1 disease with a slow natural history or high competing death risk.

Kidney and Urinary Tract Imaging: Triple-Bolus Multidetector CT Urography as a One-Stop Shop—Protocol Design, Opacification, and Image Quality Analysis

PURPOSE To retrospectively evaluate renal, vascular, and urinary tract visualization following a single postcontrast multidetector computed tomographic (CT) urographic sequence performed with three limited-volume bolus injections. MATERIALS AND METHODS The institutional review board approved this retrospective study. Patient informed consent was waived. Triple-bolus multidetector CT urography was performed in 110 patients. Triple-bolus protocol consisted of 30 mL of contrast material at 2 mL/sec at 0 seconds, 50 mL at 1.5 mL/sec at 435 seconds, 65 mL at 3 mL/sec at 488 seconds, with total abdominal scanning time of 510 seconds. Two independent readers rated urinary tract opacification and qualitatively and quantitatively assessed renal parenchymal and vascular contrast enhancement. Upper urinary tract (UUT) distention was measured by one reader. Interobserver agreement was assessed by using kappa statistics. RESULTS Complete opacification of the intrarenal collecting system and proximal ureter was achieved in 91% (184 of 202) (kappa = 0.62) and 82% (166 of 202) (kappa = 0.94) of segments, respectively. The distal ureter was not opacified in 21% of the cases (kappa = 0.92), and the bladder was not opacified in 20% of the cases. Mean distention was higher for proximal (3.9 mm) than for distal (3.7 mm) segments. Image quality of renal parenchymal enhancement was excellent in 76% of cases. Arteries showed better contrast enhancement than veins (excellent rating in 89% vs 59% of the cases). Radiation dose calculated for triple-bolus acquisition was 9.8 mSv. CONCLUSION Triple-bolus multidetector CT urography is a dose-efficient protocol acquiring corticomedullary-nephrographic-excretory and vascular enhancement phases in a single acquisition and provides sufficient opacification and distention of the UUT. Simultaneously, adequate image quality of renal parenchyma and vascular anatomy is achieved.

Expression of the Androgen-Regulated Fusion Gene TMPRSS2-ERG Does Not Predict Response to Endocrine Treatment in Hormone-Naïve, Node-Positive Prostate Cancer

BACKGROUND Fusion of the androgen-regulated gene transmembrane protease, serine 2, TMPRSS2, to the v-ets erythroblastosis virus E26 oncogene homolog (avian), ERG, of the erythroblast transformation-specific (ETS) family is the most common genetic alteration in prostate cancer (PCa). OBJECTIVE To determine whether expression of androgen-regulated TMPRSS2-ERG predicts response to endocrine treatment in hormone-naïve, node-positive PCa. DESIGN, SETTING, AND PARTICIPANTS Eighty-five patients with histologically confirmed, node-positive PCa who were without treatment at the moment of lymph node dissection were analysed. RNA was isolated from the paraffin-embedded lymph node metastases and complementary DNA (cDNA) was made. The quality of cDNA was tested by polymerase chain reaction (PCR) analysis of the expression of the housekeeping gene hydroxymethylbilane synthase, HMBS (formerly PBGD). TMPRSS2-ERG expression was analysed by PCR using a forward primer in TMPRSS2 exon 1 and a reverse primer in ERG exon 4. MEASUREMENTS The primary end point was time from start of endocrine therapy to the occurrence of three consecutive rises in prostate-specific antigen (PSA) that were at least 2 wk apart and resulted in two 50% increases over the PSA nadir. Secondary end points were time to PSA nadir after start of endocrine treatment and cancer-specific and overall survival. RESULTS AND LIMITATIONS TMPRSS2-ERG was expressed in 59% of the 71 patients who could be analysed. Median duration of response to endocrine therapy was 20.9 mo versus 24.1 mo for gene fusion-positive versus gene fusion-negative patients (95% confidence intervals: 18.6-23.1 vs 18.9-29.4, p=0.70). Furthermore, no significant differences were seen between the two groups for the secondary end points. CONCLUSIONS Expression of TMPRSS2-ERG is frequent in lymph node metastases of patients with untreated PCa; however, expression of this androgen-regulated fusion gene did not correspond with duration of response to endocrine therapy. Our results suggest that expression of TMPRSS2-ERG is not a candidate marker to select for metastatic PCa patients who will benefit more from endocrine treatment.

Percutaneous nephrolithotomy for treating renal calculi in children

There are various topics covered in the paediatric section this month. Another series of percutaneous nephrolithotomy is reported, as is the necessity or not to use the GFR in the follow‐up of children who have had a unilateral nephrectomy.

Current vaccination strategies for prostate cancer

CONTEXT The first therapeutic cancer vaccine demonstrating effectiveness in a phase 3 study was approved by the US Food and Drug Administration on 29 April 2010. The pivotal trial demonstrated overall survival (OS) benefit in patients treated with antigen-loaded leukapheresis cells compared with a control infusion. Results of other prostate cancer (PCa) vaccination strategies are awaited, as this approach may herald a new era in the care for patients with advanced PCa. OBJECTIVE Consider effectiveness and safety of vaccination strategies in the treatment of PCa. EVIDENCE ACQUISITION We searched three bibliographic databases (January 1995 through October 2010) for randomised phase 2 and 3 studies of vaccination strategies for PCa based on predetermined relevant Medical Subject Heading terms and free text terms. EVIDENCE SYNTHESIS Data from 3 randomised phase 3 and 10 randomised phase 2 vaccination trials are discussed with respect to clinical outcome in terms of progression-free survival and OS, toxicity, prostate-specific antigen (PSA) response, and immunologic response. Three phase 3 trials (D9901, D9902A, and D9902B) that enrolled a total of 737 patients, all controlled and double-blinded, tested the efficacy of sipuleucel-T. The largest of these three trials, called Immunotherapy for Prostate Adenocarcinoma Treatment (IMPACT), has demonstrated safety and effectiveness of sipuleucel-T (now marketed as Provenge) as measured by prolonged survival of 512 asymptomatic patients with metastatic castration-resistant PCa (mCRPC). The study showed a 4.1-mo median survival benefit in the sipuleucel-T vaccine-treated group compared with the control group (25.8 vs 21.7 mo; hazard ratio [HR]: 0.78; 95% confidence interval [CI], 0.62-0.98; p=0.032) and extended 3-yr survival (31.7% vs 23.0%). In contrast, two phase 3 vaccination trials with a whole-tumour-cell mixture of two PCa cell lines (GVAX) and testing GVAX either alone or in combination with chemotherapy versus chemotherapy alone (VITAL1 and 2) were terminated prematurely based on futility and increased deaths. Other phase 2 vaccination trials testing different types of vaccines in castration-resistant PCa patients have been reported with variable outcomes. Notably, a controlled, double-blind, randomised phase 2 vaccine trial of PROSTVAC-VF, a recombinant viral vector containing complementary DNA encoding PSA, in 125 patients with chemotherapy-naïve, minimally symptomatic mCRPC also demonstrated safety but no significant effect on the time to disease progression. In comparison with controls (n=40), PROSTVAC-VF-treated patients (n=82) experienced longer median survival of 8.5 mo (25.1 vs 16.6 mo; HR: 0.56; 95% CI, 0.37-0.85; p=0.0061) and extended 3-yr survival (30% vs 17%). In general, PCa vaccines are perceived to have less toxicity compared with current cytotoxic or targeted therapies. Evaluation of clinical efficacy of different vaccination strategies (eg, protein-, peptide- and DNA-based vaccines) in the context of properly designed and controlled phase 3 studies is warranted. CONCLUSIONS Cancer vaccines represent a new paradigm in the treatment of PCa. The IMPACT trial showed improved survival but no difference in time to disease progression in mCRPC patients with minimal tumour burden. Observations in phase 2 and 3 trials pave the way for other vaccination approaches for this disease, raise questions regarding the most appropriate clinical trial designs, and underscore the importance of identifying biomarkers for antitumour effect to better implement such therapies.

Histopathological characteristics of lymph node metastases predict cancer-specific survival in node-positive prostate cancer.

To correlate the histopathological characteristics of lymph node metastases in prostate cancer with cancer‐specific survival (CSS).

Deletion of chromosomal region 6q14-16 in prostate cancer.

A detailed analysis of chromosome 6 in DNAs from prostate cancers was performed, to define a region for subsequent search for cancer genes. DNA from 4 prostate cancer cell lines and 11 xenografts was used for CGH and whole‐chromosome allelotyping with polymorphic microsatellite markers. Loss of proximal 6q was studied in more detail by high‐density allelotyping of xenografts, cell lines and 19 prostate tumour specimens from TURP. Seven of 15 xenografts and cell lines showed deletion of proximal 6q by CGH. Gain of 6q was found in 2 samples. Six samples showed 6p gain, and 1 had 6p loss. Allelotyping results were consistent with CGH data in 11 of 15 DNAs. In LNCaP and DU145 cells, CGH showed 6p loss and 6q loss, respectively, but 2 allelic bands were detected for many polymorphic markers on these chromosome arms. These apparent discrepancies might be explained by aneuploidy. In cell line TSU, allelotyping demonstrated chromosome 6 deletion, which was not clearly detected by CGH, indicating loss of 1 copy of chromosome 6 followed by gain of the retained copy during progressive tumour growth. Loss of heterozygosity was detected in 9 of 19 TURP specimens. Combining all data, we found a common minimal region of loss at 6q14‐16 with a length of 8.6 Mbp flanked by markers D6S1609 and D6S417. One hundred and twenty‐three STSs, ESTs, genes and candidate genes mapping in this interval were used to screen xenografts and cell lines for HDs, but none was detected. In summary, chromosome region 6q14‐16 was deleted in approximately 50% of the prostate cancer specimens analysed. The high percentage of loss underscores the importance of genes within this region in prostate cancer growth.

E17K substitution in AKT1 in prostate cancer

Background:The phosphatidylinositol 3-kinase (PI3K)–AKT pathway is activated in many cancers. Mutational hotspots in AKT1 and in the regulatory and catalytic subunits of PI3K have been detected in multiple tumour types. In AKT1, the E17K substitution leads to a PI3K-independent activation of AKT1.Methods:A mutational profiling of AKT1 and of the mutational hotspots in PIK3CA and PIK3R1 was carried out in samples from primary and recurrent prostate tumours.Results:We show that, in prostate cancer, AKT1(E17K) had a prevalence of 1.4%. The mutation seemed to be associated with a favourable clinical course but it was not associated with a specific tumour growth pattern. Activating mutations in PIK3CA or PIK3R1 were not found in prostate cancer.Conclusion:The E17K substitution in AKT1 is rare in prostate cancer. It seems associated with a favourable clinical outcome but not with a specific histology of the tumour.

Prognostic factors in localised prostate cancer with emphasis on the application of molecular techniques

Prostate cancer is the most prevalent malignancy in males in the Western world and the second leading cause of male cancer death. Prostate specific antigen (PSA) based screening and case finding leads to identification of early stage prostate cancer. It is often difficult to discriminate between patients that need curative treatment and those that can be managed conservatively. Prognostic factors are used to make this clinical decision. Based on the classification proposed by the American College of Pathologists and the World Health Organisation, selected prognostic factors in prostate cancer are described. Clinical applicable factors are stage, grade and serum PSA. Prognostic factors that are not routinely used (for various reasons) are ploidy, histological type and cancer volume in needle biopsies. All other factors (including circulating tumour cells, angiogenesis, growth factors, proliferation rate, apoptosis, nuclear morphometry, neuroendocrine differentiation, loss of chromosomal regions, tumour suppresser genes and adhesion molecules) are promising as prognostic factor although currently their use in clinical decisions is not recommended. The role of these factors in prostate cancer growth and their predictive value are discussed. The rapid developments in molecular techniques allow assessment of structure or function of thousands of genes in a prostate biopsy sample. We expect that molecular characterisation of tumour material will become a clinically important tool to predict prognosis in patients with localised prostate cancer.