Sheila M.J. Aubin

PCA3: A Molecular Urine Assay for Predicting Prostate Biopsy Outcome

PURPOSE A urinary assay for PCA3, an mRNA that is highly over expressed in prostate cancer cells, has shown usefulness as a diagnostic test for this common malignancy. We further characterized PCA3 performance in different groups of men and determined whether the PCA3 score could synergize with other clinical information to predict biopsy outcome. MATERIALS AND METHODS Prospectively urine was collected following standardized digital rectal examination in 570 men immediately before prostate biopsy. Urinary PCA3 mRNA levels were quantified and then normalized to the amount of prostate derived RNA to generate a PCA3 score. RESULTS The percent of biopsy positive men identified increased directly with the PCA3 score. PCA3 assay performance was equivalent in the first vs previous negative biopsy groups with an area under the ROC curve of 0.70 and 0.68, respectively. Unlike serum prostate specific antigen the PCA3 score did not increase with prostate volume. PCA3 assay sensitivity and specificity were equivalent at serum prostate specific antigen less than 4, 4 to 10 and more than 10 ng/ml. A logistic regression algorithm using PCA3, serum prostate specific antigen, prostate volume and digital rectal examination result increased the AUC from 0.69 for PCA3 alone to 0.75 (p = 0.0002). CONCLUSIONS PCA3 is independent of prostate volume, serum prostate specific antigen level and the number of prior biopsies. The quantitative PCA3 score correlated with the probability of positive biopsy. Logistic regression results suggest that the PCA3 score could be incorporated into a nomogram for improved prediction of biopsy outcome. The results of this study provide further evidence that PCA3 is a useful adjunct to current methods for prostate cancer diagnosis.

Urine TMPRSS2:ERG Fusion Transcript Stratifies Prostate Cancer Risk in Men with Elevated Serum PSA

Urine TMPRSS2:ERG gene fusion could be used for stratification of patients at higher risk for prostate cancer. Old Gene Fusion, New Diagnostic Tricks The “PSA test” is a routine test for men over the age of 50 or for those at risk for prostate cancer. It measures the level of prostate-specific antigen (PSA) in the blood, and if that level is above a predefined cutoff, a biopsy is recommended for definitive diagnosis. This test is not perfect; benign conditions, such as an enlarged prostate, can contribute to high levels of PSA, resulting in a “false-positive” and subsequent overdiagnosis and overtreatment. Because of the high prevalence of prostate cancer (it is estimated that nearly 250,000 men will be diagnosed with the disease in 2011), it is clear that a more accurate test for prostate cancer is needed. Here, Tomlins et al. improve on the PSA test by taking a new twist on a known gene fusion, using it to stratify more than 1000 men in two multicenter cohorts based on risk for developing the disease. Recently, it was discovered that the fusion of two genes, the transmembrane protease, serine 2 (TMPRSS2) gene and the v-ets erythroblastosis virus E26 oncogene homolog (avian) (ERG) gene, known as TMPRSS2:ERG, is overexpressed in more than 50% of PSA-screened prostate cancers. The protein product of this fusion cannot be detected in serum, so the authors decided to test for the presence of TMPRSS2:ERG mRNA in urine. First, they developed a clinical-grade, transcription-mediated amplification assay for quantifying fusion mRNA—this generated a TMPRSS2:ERG “score.” Urine TMPRSS2:ERG score was linked to the presence of cancer, tumor volume, and clinically significant cancer in patients. Then, the authors combined the TMPRSS2:ERG score with the level of prostate cancer antigen 3 (PCA3) in urine. TMPRSS2:ERG+PCA3 improved the performance of the multivariate Prostate Cancer Prevention Trial risk calculator, thus demonstrating clinical utility. Who said you can’t teach an old gene fusion new tricks? By combining the cancer-specific fusion TMPRSS2:ERG score with levels of PSA (in serum) and PCA3 (in urine), Tomlins and colleagues demonstrated more accurate, individualized stratification of men at high risk for developing clinically significant prostate cancer—an important step in streamlining diagnosis and treatment. Moreover, men with extremes of TMPRSS2:ERG+PCA3 had different risks of cancer on biopsy; in combination with other clinicopathological features, urine TMPRSS2:ERG+PCA3 might also inform the urgency of biopsy after PSA screening. More than 1,000,000 men undergo prostate biopsy each year in the United States, most for “elevated” serum prostate-specific antigen (PSA). Given the lack of specificity and unclear mortality benefit of PSA testing, methods to individualize management of elevated PSA are needed. Greater than 50% of PSA-screened prostate cancers harbor fusions between the transmembrane protease, serine 2 (TMPRSS2) and v-ets erythroblastosis virus E26 oncogene homolog (avian) (ERG) genes. Here, we report a clinical-grade, transcription-mediated amplification assay to risk stratify and detect prostate cancer noninvasively in urine. The TMPRSS2:ERG fusion transcript was quantitatively measured in prospectively collected whole urine from 1312 men at multiple centers. Urine TMPRSS2:ERG was associated with indicators of clinically significant cancer at biopsy and prostatectomy, including tumor size, high Gleason score at prostatectomy, and upgrading of Gleason grade at prostatectomy. TMPRSS2:ERG, in combination with urine prostate cancer antigen 3 (PCA3), improved the performance of the multivariate Prostate Cancer Prevention Trial risk calculator in predicting cancer on biopsy. In the biopsy cohorts, men in the highest and lowest of three TMPRSS2:ERG+PCA3 score groups had markedly different rates of cancer, clinically significant cancer by Epstein criteria, and high-grade cancer on biopsy. Our results demonstrate that urine TMPRSS2:ERG, in combination with urine PCA3, enhances the utility of serum PSA for predicting prostate cancer risk and clinically relevant cancer on biopsy.

PCA3 Molecular Urine Test for Predicting Repeat Prostate Biopsy Outcome in Populations at Risk: Validation in the Placebo Arm of the Dutasteride REDUCE Trial

PURPOSE We determined the performance of PCA3 alone and in the presence of other covariates as an indicator of contemporaneous and future prostate biopsy results in a population with previous negative biopsy and increased serum prostate specific antigen. MATERIALS AND METHODS Urine PCA3 scores were determined before year 2 and year 4 biopsies from patients in the placebo arm of the REDUCE trial, a prostate cancer risk reduction study evaluating men with moderately increased serum prostate specific antigen results and negative biopsy at baseline. PCA3, serum prostate specific antigen and percent free prostate specific antigen results were correlated with biopsy outcome via univariate logistic regression and ROC analyses. Multivariate logistic regression was also performed including these biomarkers together with prostate volume, age and family history. RESULTS PCA3 scores were measurable from 1,072 of 1,140 subjects (94% informative rate). PCA3 scores were associated with positive biopsy rate (p <0.0001) and correlated with biopsy Gleason score (p = 0.0017). PCA3 AUC of 0.693 was greater than serum prostate specific antigen (0.612, p = 0.0077 vs PCA3). The multivariate logistic regression model yielded an AUC of 0.753 and exclusion of PCA3 from the model decreased AUC to 0.717 (p = 0.0009). PCA3 at year 2 was a significant predictor of year 4 biopsy outcome (AUC 0.634, p = 0.0002), whereas serum prostate specific antigen and free prostate specific antigen were not predictive (p = 0.3281 and 0.6782, respectively). CONCLUSIONS PCA3 clinical performance was validated in the largest repeat biopsy study to date. Increased PCA3 scores indicated increased risk of contemporaneous cancers and predicted future biopsy outcomes. Use of PCA3 in combination with serum prostate specific antigen and other risk factors significantly increased diagnostic accuracy.

Prostate cancer gene 3 score predicts prostate biopsy outcome in men receiving dutasteride for prevention of prostate cancer: results from the REDUCE trial.

OBJECTIVES To examine the ability of the urinary prostate cancer gene 3 (PCA3) assay to predict biopsy-detected cancers in men receiving dutasteride in the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) study cohort. METHODS Urine and serum samples from 930 men in the active arm were acquired at years 2 and 4 of the biopsy visits. In addition to univariate logistic regression and receiver operating characteristic analysis, multivariate analysis for association with biopsy outcome was performed for PCA3 score in the presence of serum prostate-specific antigen (PSA), age, prostate volume, and family history of prostate cancer. RESULTS At year 2, the univariate PCA3 score area under the receiver operating characteristic curve (AUC) was 0.668 versus 0.603 for PSA. At year 4, the PCA3 assay significantly predicted the biopsy outcome (AUC 0.628, 95% confidence interval 0.556-0.700), and the PSA level was not predictive (AUC 0.556, 95% confidence interval 0.469-0.642). The year 2 multivariate model yielded an AUC of 0.712. Removing the PCA3 score decreased the AUC to 0.660 (P = .0166 vs the full model). The median PCA3 scores in the dutasteride arm were not different from those in the 1072 men in the placebo arm (16.2 and 17.2 at year 2, P = .1755; and 18.8 and 18.1 at year 4, P = .2340, respectively). However, the PSA values were reduced >50% in the dutasteride arm at both visits (both P < .0001 vs placebo). At a PCA3 score cutoff of 35, the sensitivity and specificity were equivalent between the 2 arms. CONCLUSIONS In the present study, the PCA3 assay outperformed PSA for cancer detection in men undergoing dutasteride treatment and improved the diagnostic accuracy when combined with the PSA level and other clinical variables. In addition, no adjustment in PCA3 score was needed to yield equivalent clinical performance between the dutasteride and placebo arms. These findings are particularly important in light of the potential role of dutasteride for prostate cancer chemoprevention.

Abstract 899: TMPRSS2:ERG urine test identifies Gleason score upgrading and significant prostate cancer

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Objective: In men diagnosed with prostate cancer (PCa) at biopsy, a major challenge is correctly stratifying those with indolent versus significant PCa for treatment selection. The extent and grade of PCa is assessed in part based on standard risk factors, biopsy Gleason score (bx GS) and the number of positive biopsy cores. However, due to under-sampling at biopsy, upgrading in Gleason score is often seen from biopsy to prostatectomy. In this study we evaluated a TMPRSS2:ERG (T2:ERG) urine test for its ability to identify significant cancer and upgrading at prostatectomy. Methods: Post-DRE urine specimens were prospectively collected from 218 men referred for prostatectomy. T2:ERG mRNA copies were quantified using a transcription-mediated amplification assay and normalized to PSA mRNA copies to calculate a T2:ERG score. The prototype T2:ERG urine assay detects the gene fusion mRNA isoform TMPRSS2 exon 1 to ERG exon 4. T2:ERG score was correlated to prostatectomy Gleason score (px GS) and significant cancer as defined by the Epstein criteria at prostatectomy. Results: Of 185 men scheduled for radical prostatectomy, 61 had low risk of significant cancer based on having bx GS 7, p = 0.0076). At biopsy, 70 men were found to have low-grade cancer (bx GS<6), but upon prostatectomy, upgrading was seen in 50% of these men. T2:ERG was able to identify 40% of men with bx GS<6 that were later upgraded. Conclusions: A T2:ERG urine test may help identify significant cancers and Gleason score upgrading, and increase predictive accuracy when used in combination with currently available methods. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 899. doi:10.1158/1538-7445.AM2011-899

Abstract 2815: Urine TMPRSS2:ERG for prostate cancer risk stratification in men with elevated serum PSA

Background: Over 1,000,000 men undergo prostate biopsy each year in the U.S., most for “elevated” serum PSA. Given the lack of sensitivity and specificity, and unclear mortality benefit of PSA testing, methods to individualize management of elevated PSA are needed. We evaluated urine expression of TMPRSS2:ERG, a gene fusion occurring in 50% of prostate cancers, for risk-stratifying men presenting for biopsy. Methods: TMPRSS2:ERG was measured by a clinical grade, transcription-mediated-amplification assay in prospectively collected whole-urine from 1,094 men undergoing biopsy at 10 academic and community clinics. Findings: Urine TMPRSS2:ERG was associated with indicators of clinically significant cancer at biopsy and prostatectomy, including tumor size, high prostatectomy Gleason score and upgrading at prostatectomy. TMPRSS2:ERG in combination with urine PCA3, improved the multivariate PCPT risk calculator performance for predicting cancer on biopsy (AUC in test set, 0.79 vs. 0.64, p Interpretation: Urine TMPRSS2:ERG, in combination with urine PCA3, enhances the utility of serum PSA for predicting prostate cancer and clinically relevant cancer on biopsy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2815. doi:10.1158/1538-7445.AM2011-2815