Jing Xia

Prostate Cancer Mortality following Active Surveillance versus Immediate Radical Prostatectomy

Propose: Active surveillance has been endorsed for low-risk prostate cancer, but information about long-term outcomes and comparative effectiveness of active surveillance is lacking. The purpose of this study is to project prostate cancer mortality under active surveillance followed by radical prostatectomy versus under immediate radical prostatectomy. Experimental design: A simulation model was developed to combine information on time from diagnosis to treatment under active surveillance and associated disease progression from a Johns Hopkins active surveillance cohort (n = 769), time from radical prostatectomy to recurrence from cases in the CaPSURE database with T-stage ≤ T2a (n = 3,470), and time from recurrence to prostate cancer death from a T-stage ≤ T2a Johns Hopkins cohort of patients whose disease recurred after radical prostatectomy (n = 963). Results were projected for a hypothetical cohort aged 40 to 90 years with low-risk prostate cancer (T-stage ≤ T2a, Gleason score ≤ 6, and prostate-specific antigen level ≤ 10 ng/mL). Results: The model projected that 2.8% of men on active surveillance and 1.6% of men with immediate radical prostatectomy would die of their disease in 20 years. Corresponding lifetime estimates were 3.4% for active surveillance and 2.0% for immediate radical prostatectomy. The average projected increase in life expectancy associated with immediate radical prostatectomy was 1.8 months. On average, the model projected that men on active surveillance would remain free of treatment for an additional 6.4 years relative to men treated immediately. Conclusions: Active surveillance is likely to produce a very modest decline in prostate cancer-specific survival among men diagnosed with low-risk prostate cancer but could lead to significant benefits in terms of quality of life. Clin Cancer Res; 18(19); 5471–8. ©2012 AACR.

Precision Medicine in Active Surveillance for Prostate Cancer: Development of the Canary-Early Detection Research Network Active Surveillance Biopsy Risk Calculator.

BACKGROUND Men on active surveillance (AS) face repeated biopsies. Most biopsy specimens will not show disease progression or change management. Such biopsies do not contribute to patient management and are potentially morbid and costly. OBJECTIVE To use a contemporary AS prospective trial to develop a tool to predict AS biopsy outcomes. DESIGN, SETTING, AND PARTICIPANTS Biopsy samples (median: 2; range: 2-9 per patient) from 859 men participating in the Canary Prostate Active Surveillance Study and with Gleason 6 prostate cancer (median follow-up: 35.8 mo; range: 3.0-148.7 mo) were analyzed. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Logistic regression was used to predict progression, defined as an increase in Gleason score from ≤6 to ≥7 or increase in percentage of cores positive for cancer from <34% to ≥34%. Fivefold internal cross-validation was performed to evaluate the area under the receiver operating characteristic curve (AUC). RESULTS AND LIMITATIONS Statistically significant risk factors for progression on biopsy were prostate-specific antigen (odds ratio [OR]: 1.045; 95% confidence interval [CI], 1.028-1.063), percentage of cores positive for cancer on most recent biopsy (OR: 1.401; 95% CI, 1.301-1.508), and history of at least one prior negative biopsy (OR: 0.524; 95% CI, 0.417-0.659). A multivariable predictive model incorporating these factors plus age and number of months since last biopsy achieved an AUC of 72.4%. CONCLUSIONS A combination of readily available clinical measures can stratify patients considering AS prostate biopsy. Risk of progression or upgrade can be estimated and incorporated into clinical practice. PATIENT SUMMARY The Canary-Early Detection Research Network Active Surveillance Biopsy Risk Calculator, an online tool, can be used to guide patient decision making regarding follow-up prostate biopsy.

A Reality Check for Overdiagnosis Estimates Associated With Breast Cancer Screening

The frequency of overdiagnosis associated with breast cancer screening is a topic of controversy. Published estimates vary widely, but identifying which estimates are reliable is challenging. In this article we present an approach that provides a check on these estimates. Our approach leverages the close link between overdiagnosis and lead time by identifying the average lead time most consistent with a given overdiagnosis frequency. We consider a high-profile study that suggested that 31% of breast cancers diagnosed in the United States in 2008 were overdiagnosed and show that this corresponds to an average lead time of about nine years among localized cases. Comparing this estimate with the average lead time for invasive, screen-detected breast cancers of 40 months, around which there is a relative consensus, suggests the published estimate of overdiagnosis is excessive. This approach provides a novel way to appraise estimates of overdiagnosis given knowledge of disease natural history.

Single cell transcriptomic analysis of prostate cancer cells

BackgroundThe ability to interrogate circulating tumor cells (CTC) and disseminated tumor cells (DTC) is restricted by the small number detected and isolated (typically <10). To determine if a commercially available technology could provide a transcriptomic profile of a single prostate cancer (PCa) cell, we clonally selected and cultured a single passage of cell cycle synchronized C4-2B PCa cells. Ten sets of single, 5-, or 10-cells were isolated using a micromanipulator under direct visualization with an inverted microscope. Additionally, two groups of 10 individual DTC, each isolated from bone marrow of 2 patients with metastatic PCa were obtained. RNA was amplified using the WT-Ovation™ One-Direct Amplification System. The amplified material was hybridized on a 44K Whole Human Gene Expression Microarray. A high stringency threshold, a mean Alexa Fluor® 3 signal intensity above 300, was used for gene detection. Relative expression levels were validated for select genes using real-time PCR (RT-qPCR).ResultsUsing this approach, 22,410, 20,423, and 17,009 probes were positive on the arrays from 10-cell pools, 5-cell pools, and single-cells, respectively. The sensitivity and specificity of gene detection on the single-cell analyses were 0.739 and 0.972 respectively when compared to 10-cell pools, and 0.814 and 0.979 respectively when compared to 5-cell pools, demonstrating a low false positive rate. Among 10,000 randomly selected pairs of genes, the Pearson correlation coefficient was 0.875 between the single-cell and 5-cell pools and 0.783 between the single-cell and 10-cell pools. As expected, abundant transcripts in the 5- and 10-cell samples were detected by RT-qPCR in the single-cell isolates, while lower abundance messages were not. Using the same stringency, 16,039 probes were positive on the patient single-cell arrays. Cluster analysis showed that all 10 DTC grouped together within each patient.ConclusionsA transcriptomic profile can be reliably obtained from a single cell using commercially available technology. As expected, fewer amplified genes are detected from a single-cell sample than from pooled-cell samples, however this method can be used to reliably obtain a transcriptomic profile from DTC isolated from the bone marrow of patients with PCa.

Effects of Screening on Radical Prostatectomy Efficacy: The Prostate Cancer Intervention Versus Observation Trial

BACKGROUND The Scandinavian Prostate Cancer Group Study Number 4 (SPCG-4) trial showed that radical prostatectomy (RP) reduced prostate cancer deaths with an absolute mortality difference (AMD) between the RP and watchful waiting arms of 6.1% (95% confidence interval [CI] = 0.2% to 12.0%) after 15 years. In the United States, the Prostate Cancer Intervention Versus Observation Trial (PIVOT) produced an AMD of 3% (95% CI = -1.1% to 6.5%) after 12 years. It is not known whether a higher frequency of screen detection in PIVOT explains the lower AMD. METHODS We assumed the SPCG-4 trial represents RP efficacy and prostate cancer survival in an unscreened population. Given the fraction of screen-detected prostate cancers in PIVOT, we adjusted prostate cancer survival using published estimates of overdiagnosis and lead time to project the effect of screen detection on disease-specific deaths. RESULTS On the basis of published estimates, we assumed that 32% of screen-detected cancers were overdiagnosed and a mean lead time among non-overdiagnosed cancers of 7.7 years. When we adjusted prostate cancer survival for the 76% of case patients in PIVOT who were screen detected, we projected that the AMD after 12 years would be 2.0% (95% CI = -1.6% to 5.6%) based on variation in published estimates of overdiagnosis and mean lead time in the United States. CONCLUSIONS If RP efficacy and prostate cancer survival in the absence of screening are similar to that in the SPCG-4 trial, then overdiagnosis and lead time largely explain the lower AMD in PIVOT. If these artifacts of screening are the correct explanation, then there is a subset of case subjects that should not be treated with RP, and identifying this subset should lead to a clearer understanding of the benefit of RP in the remaining cases.

Overdetection of Recurrence after Radical Prostatectomy: Estimates Based on Patient and Tumor Characteristics

Purpose: Prostate-specific antigen recurrence (PSA-R) after radical prostatectomy (RP) can occur years before metastasis. This study estimates the chance that an untreated PSA-R would not progress to clinical metastasis within the patients lifetime, that is, that recurrence is overdetected. Experimental Design: Times from PSA-R to metastasis were estimated from patients with RP treated at Johns Hopkins University (Baltimore, MD) who did not receive salvage treatment (n = 441) at PSA-R. Times to other-cause death were based on U.S. life tables adjusted to reflect other-cause survival among RP cases in the Surveillance, Epidemiology, and End Results (SEER) registry. We used competing risks simulation to estimate lower bounds on the chance that other-cause death would precede clinical metastasis for patients with disease characteristics at diagnosis based on the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) database (n = 4,455). Results: Cumulative incidence of PSA-R in CaPSURE was 13.6% at 5 years and 19.9% at 10 years. The risk of other-cause death among patients with RP in SEER was 60% lower than the age-matched U.S. population. At least 9.1% of patients with PSA-R <5 years after RP and at least 15.6% of patients with PSA-R 5 to 10 years after RP were overdetected. At least 31.4% of patients over the age of 70 years at diagnosis, who recurred <10 years of diagnosis, were overdetected. Conclusions: This analysis indicates that PSA-R after RP may be overdetected, with risk depending on patient age and tumor characteristics. The potential for overdetection of recurrence confirms the need for approaches to determine whether and when to initiate salvage therapies. Clin Cancer Res; 20(20); 5302–10. ©2014 AACR.

High-Resolution Genomic Profiling of Disseminated Tumor Cells in Prostate Cancer

Circulating tumor cells and disseminated tumor cells (DTCs) are of great interest because they provide a minimally invasive window for assessing aspects of cancer biology, including tumor heterogeneity, a means to discover biomarkers of disease behavior, and a way to identify and prioritize therapeutic targets in the emerging era of precision oncology. However, the rarity of circulating tumor cells and DTCs poses a substantial challenge to the consistent success in analyzing their molecular features, including genomic aberrations. Herein, we describe optimized and robust methods to reproducibly detect genomic copy number alterations in samples of 2 to 40 cells after whole-genome amplification with the use of a high-resolution single-nuclear polymorphism-array platform and refined computational algorithms. We have determined the limit of detection for heterogeneity within a sample as 50% and also demonstrated success in analyzing single cells. We validated the genes in genomic regions that are frequently amplified or deleted by real-time quantitative PCR and nCounter copy number quantification. We further applied these methods to DTCs isolated from individuals with advanced prostate cancer to confirm their highly aberrant nature. We compared copy number alterations of DTCs with matched metastatic tumors isolated from the same individual to gain biological insight. These developments provide high-resolution genomic profiling of single and rare cell populations and should be applicable to a wide-range of sample sources.

A novel system for estimating residual disease and pathologic response to neoadjuvant treatment of prostate cancer

Pathologic variables that characterize response of prostate carcinoma to current neoadjuvant therapy have not been characterized in detail. This study reports (i) the histological features of prostate cancer treated with abiraterone and enzalutamide and inter‐pathologist variance in identifying these features, and (ii) the effect of the novel androgen deprivation agents on residual cancer volume.

Prostate cancer characteristics associated with response to pre-receptor targeting of the androgen axis

Background Factors influencing differential responses of prostate tumors to androgen receptor (AR) axis-directed therapeutics are poorly understood, and predictors of treatment efficacy are needed. We hypothesized that the efficacy of inhibiting DHT ligand synthesis would associate with intra-tumoral androgen ratios indicative of relative dependence on DHT-mediated growth. Methods We characterized two androgen-sensitive prostate cancer xenograft models after androgen suppression by castration in combination with the SRD5A inhibitor, dutasteride, as well as a panel of castration resistant metastases obtained via rapid autopsy. Results In LuCaP35 tumors (intra-tumoral T:DHT ratio 2∶1) dutasteride suppressed DHT to 0.02 ng/gm and prolonged survival vs. castration alone (337 vs.152 days, HR 2.8, p = 0.0015). In LuCaP96 tumors (T:DHT 10∶1), survival was not improved despite similar DHT reduction (0.02 ng/gm). LuCaP35 demonstrated higher expression of steroid biosynthetic enzymes maintaining DHT levels (5-fold higher SRD5A1, 41 fold higher, 99-fold higher RL-HSD, p<0.0001 for both), reconstitution of intra-tumoral DHT (to ∼30% of untreated tumors), and ∼2 fold increased expression of full length AR. In contrast, LuCaP96 demonstrated higher levels of steroid catabolizing enzymes (6.9-fold higher AKR1C2, 3000-fold higher UGT2B15, p = 0.002 and p<0.0001 respectively), persistent suppression of intra-tumoral DHT, and 6–8 fold induction of full length AR and the ligand independent V7 AR splice variant. Human metastases demonstrated bio-active androgen levels and AR full length and AR splice-variant expression consistent with the range observed in xenografts. Conclusions Intrinsic differences in basal steroidogenesis, as well as variable expression of full length and splice-variant AR, associate with response and resistance to pre-receptor AR ligand suppression. Expression of steroidogenic enzymes and AR isoforms may serve as potential biomarkers of sensitivity to potent AR-axis inhibition and should be validated in additional models.

MP02-07 NOVEL URINE MARKERS FOR DIAGNOSING AND MONITORING NON-INDOLENT PROSTATE CANCER

Introduction: The clinical value of PSA for prostate cancer early detection has been questioned primarily due to its poor specificity for clinically relevant disease, namely high grade prostate cancer. This is especially true at PSA levels lower than 4 ng/mL, generally considered to be within the normal range. However, PSA values between 1.54 ng/mL have been referred to as the PSA Danger Zone because the risk of prostate cancer in men with PSA within this range is 15-18x higher compared to that in men with PSA< 1.5ng/mL. Moreover, a surprising number of otherwise healthy men with PSA less than 4 ng/mL are at risk for prostate cancer metastases and death up to 20 years later. The 4Kscore Test has been validated to predict an individual man’s risk of high grade cancer on biopsy, with an area under the curve of 0.82. This test incorporates: Total PSA (tPSA), Free PSA, Intact PSA, human Kallikrein-2, age, digital rectal examination findings, and previous biopsy information into an algorithm. The objective of this study was to see if the 4Kscore Test can predict high grade (Gleason ≥ 7) prostate cancer in men with a tPSA < 4 ng/mL.