The interaction between the immune system and prostate cancer has been an area of research interest for several decades. The recent FDA approval of two first-in-class proof of concept immunotherapies (sipuleucel-T and ipilimumab) has stimulated broader interest in manipulating immunity to fight cancer. In the context of prostate cancer, the immunotherapy strategies that have garnered the most interest are the therapeutic vaccination strategies exemplified by sipuleucel-T and PROSTVAC-VF, and immune checkpoint blockade of CTLA-4 and PD-1. Improved understanding of the immune responses generated by these strategies and development of predictive biomarkers for patient selection will guide rational combinations of these treatments and provide building blocks for future immunotherapies.
prostate cancer; immunotherapy; vaccine; immune checkpoint blockade
Sipuleucel-T, the first FDA-approved autologous cellular immunotherapy for treatment of advanced prostate cancer, is manufactured by activating peripheral blood mononuclear cells, including antigen presenting cells (APCs), with a fusion protein containing prostatic acid phosphatase. Analysis of data from three phase 3 trials was performed to immunologically characterize this therapy during the course of the three doses, and to relate the immunological responses to overall survival (OS).
Sipuleucel-T product characteristics [APC numbers, APC activation (CD54 upregulation), and total nucleated cell (TNC) numbers] were assessed in three randomized, controlled phase 3 studies (N = 737). Antigen-specific cellular and humoral responses were assessed in a subset of subjects. The relationships between these parameters and OS were assessed.
APC activation occurred in the first dose preparation [6.2-fold, (4.65, 7.70); median (25th, 75th percentile)] and increased in the second [10.6-fold (7.83, 13.65)] and third [10.5-fold (7.89, 13.65)] dose preparations. Cytokines and chemokines associated with activated APCs were produced during the manufacture of each dose; T-cell activation-associated cytokines were detected in the second and third dose preparations. Antigen-specific T cells were detectable after administration of the first sipuleucel-T dose. Cumulative APC activation, APC number, and TNC number correlated with OS (P < 0.05). Antigen-specific immune responses were observed in 78.8 % of monitored subjects and their presence correlated with OS (P = 0.003).
Sipuleucel-T broadly engages the immune system by activating APCs ex vivo and inducing long-lived immune responses in vivo. These data indicate antigen-specific immune activation as a mechanism by which sipuleucel-T prolongs OS.
Electronic supplementary material
The online version of this article (doi:10.1007/s00262-012-1317-2) contains supplementary material, which is available to authorized users.
Prostate cancer; Cellular; Humoral; Immunotherapy; Survival
Androgen deprivation therapy (ADT), an important treatment for advanced prostate cancer, is highly variable in its effectiveness. We hypothesized that genetic variants of androgen transporter genes, SLCO2B1 and SLCO1B3, may determine time to progression on ADT.
Patients and Methods
A cohort of 538 patients with prostate cancer treated with ADT was genotyped for SLCO2B1 and SLCO1B3 single nucleotide polymorphisms (SNP). The biologic function of a SLCO2B1 coding SNP in transporting androgen was examined through biochemical assays.
Three SNPs in SLCO2B1 were associated with time to progression (TTP) on ADT (P < .05). The differences in median TTP for each of these polymorphisms were about 10 months. The SLCO2B1 genotype, which allows more efficient import of androgen, enhances cell growth and is associated with a shorter TTP on ADT. Patients carrying both SLCO2B1 and SLCO1B3 genotypes, which import androgens more efficiently, exhibited a median 2-year shorter TTP on ADT, demonstrating a gene-gene interaction (Pinteraction = .041).
Genetic variants of SLCO2B1 and SLCO1B3 may function as pharmacogenomic determinants of resistance to ADT in prostate cancer.
Data suggest that circulating 25-hydroxyvitamin D [25(OH)D] interacts with the vitamin D receptor (VDR) to decrease proliferation and increase apoptosis for some malignancies, although evidence for prostate cancer is less clear. How VDR expression in tumor tissue may influence prostate cancer progression has not been evaluated in large studies.
Patients and Methods
We examined protein expression of VDR in tumor tissue among 841 patients with prostate cancer in relation to risk of lethal prostate cancer within two prospective cohorts, the Physicians' Health Study and Health Professionals Follow-Up Study. We also examined the association of VDR expression with prediagnostic circulating 25(OH)D and 1,25-dihydroxyvitamin D levels and with two VDR single nucleotide polymorphisms, FokI and BsmI.
Men whose tumors had high VDR expression had significantly lower prostate-specific antigen (PSA) at diagnosis (P for trend < .001), lower Gleason score (P for trend < .001), and less advanced tumor stage (P for trend < .001) and were more likely to have tumors harboring the TMPRSS2:ERG fusion (P for trend = .009). Compared with the lowest quartile, men whose tumors had the highest VDR expression had significantly reduced risk of lethal prostate cancer (hazard ratio [HR], 0.17; 95% CI, 0.07 to 0.41). This association was only slightly attenuated after adjustment for Gleason score and PSA at diagnosis (HR, 0.33; 95% CI, 0.13 to 0.83) or, additionally, for tumor stage (HR, 0.37; 95% CI, 0.14 to 0.94). Neither prediagnostic plasma vitamin D levels nor VDR polymorphisms were associated with VDR expression.
High VDR expression in prostate tumors is associated with a reduced risk of lethal cancer, suggesting a role of the vitamin D pathway in prostate cancer progression.
Prostate-specific antigen screening has led to enormous overtreatment of prostate cancer because of the inability to distinguish potentially lethal disease at diagnosis. We reasoned that by identifying an mRNA signature of Gleason grade, the best predictor of prognosis, we could improve prediction of lethal disease among men with moderate Gleason 7 tumors, the most common grade, and the most indeterminate in terms of prognosis.
Patients and Methods
Using the complementary DNA–mediated annealing, selection, extension, and ligation assay, we measured the mRNA expression of 6,100 genes in prostate tumor tissue in the Swedish Watchful Waiting cohort (n = 358) and Physicians' Health Study (PHS; n = 109). We developed an mRNA signature of Gleason grade comparing individuals with Gleason ≤ 6 to those with Gleason ≥ 8 tumors and applied the model among patients with Gleason 7 to discriminate lethal cases.
We built a 157-gene signature using the Swedish data that predicted Gleason with low misclassification (area under the curve [AUC] = 0.91); when this signature was tested in the PHS, the discriminatory ability remained high (AUC = 0.94). In men with Gleason 7 tumors, who were excluded from the model building, the signature significantly improved the prediction of lethal disease beyond knowing whether the Gleason score was 4 + 3 or 3 + 4 (P = .006).
Our expression signature and the genes identified may improve our understanding of the de-differentiation process of prostate tumors. Additionally, the signature may have clinical applications among men with Gleason 7, by further estimating their risk of lethal prostate cancer and thereby guiding therapy decisions to improve outcomes and reduce overtreatment.
Though C-C chemokine ligand 2 (CCL2) has been demonstrated to play a pivotal role in prostate cancer tumorigenesis and invasion, the role of inherited variation in the CCL2 gene in prostate cancer progression and metastases remains unanswered. This study is aimed to determine the influence of CCL2 germline variants on prostate cancer aggressiveness.
We performed an association study between six single nucleotide polymorphisms (SNPs) in the CCL2 gene and prostate cancer clinicopathologic variables in a large hospital based Caucasian patient cohort (N =4073).
Genetic variantion at CCL2 is associated with markers of disease aggressiveness. Three SNPs, each in strong linkage disequilibrium, are associated with a higher (>7) biopsy Gleason score: CCL2-1811 A/G, −2835A/C and +3726 T/C (P =0.01, 0.03 and 0.04 respectively). The CCL2 −1811 G allele is addionally associated with advanced pathologic stages in patients who underwent radical prostatectomy (P = 0.04). In haplotype analysis, we found that the frequency of a common haplotype, H5, was higher among patients with D’Amico good risk features (Ppermutation = 0.04).
These results support the influence of CCL2 variants on prostate cancer development and progression.
Prostate cancer; CCL2; Single-nucleotide Polymorphisms
To study the effects of oxidative stress on prostate cancer development as the exact biological mechanisms behind the relationship remain uncertain. We previously reported a statistically significant interaction between circulating selenium levels, variants in the superoxide dismutase 2 gene (SOD2; rs4880), and risk of developing prostate cancer and presenting with aggressive prostate cancer.
Patients and methods
We genotyped men with localized/regional prostate cancer for 26 loci across eight genes that are central to cellular antioxidant defence: glutathione peroxidase (GPX1, GPX4), peroxisome proliferator-activated receptor γ coactivator (PPARGC1A, PPARGC1B), SOD1, SOD2, and SOD3, and ‘X-ray repair complementing defective repair in Chinese hamster cell 1’ (XRCC1). Among 489 men, we examined the relationships between genotypes, circulating selenium levels, and risk of presenting with aggressive prostate cancer at diagnosis, as defined by stage, grade and prostate-specific antigen (PSA) level (213 aggressive cases).
Two variants in SOD2 were significantly associated with the risk of aggressive prostate cancer (rs17884057, odds ratio 0.83, 95% confidence interval 0.70–0.99; and rs4816407, 1.27, 1.02–1.57); men with A alleles at rs2842958 in SOD2 had lower plasma selenium levels (median 116 vs 121.8 μg/L, P = 0.03); and the association between plasma selenium levels and risk of aggressive prostate cancer was modified by SOD1 (rs10432782) and SOD2 (rs2758330).
While this study was cross-sectional and these associations might be due to chance, further research is warranted on the potential important role of antioxidant defence in prostate cancer.
single nucleotide polymorphisms; superoxide dismutase; glutathione peroxidase; aggressive prostate cancer; plasma selenium
The tumor suppressor p53 plays a crucial role in maintaining genomic stability and tumor prevention. Mdm2, Mdm4 and Hausp are all critical regulators of the p53 protein. Despite the importance of p53 pathway in prostate cancer development and progression, little is known about the association of functional SNPs in the p53 pathway genes and prostate cancer aggressiveness.
In this study, we analyze the association of SNPs in p53, Mdm2, Mdm4 and Hausp genes with prostate cancer clinicopathologic variables in a large hospital-based Caucasian prostate cancer cohort (N = 4073).
We found that the Mdm2 SNP 309 T allele was associated with earlier onset prostate cancer (P = 0.004), higher Gleason scores (P = 0.004) and higher stages men undergoing a radical prostatectomy (RP) (P = 0.011). Both the Mdm4 and Hausp SNPs (rs1380576 and rs1529916) were found to be associated with higher D’Amico risk prostate cancer category at the time of diagnosis (P = 0.023 and P = 0.046, respectively). Mdm4 SNP was also found to be associated with higher Gleason score at RP (P = 0.047). We did not observe any statistically significant association between the p53 Arg72 Pro polymorphism and prostate cancer aggressiveness or pathologic variables.
These results suggested the importance of these p53 regulators in prostate cancer development and progression.
Prostate cancer; TP53; MDM2; MDM4; HAUSP; Single-nucleotide Polymorphisms
A pressing clinical issue in prostate cancer (PCa) is to distinguish which men will have an indolent or aggressive course of disease. Clinical variables such as Gleason grade and stage are useful predictors of lethal cancer; however, the low predictive values of the common Gleason scores, changes in grading over time, and earlier diagnosis of patients due to screening limits their clinical utility. Identifying genetic variants associated with lethal PCa could inform clinical decision making.
We conducted a genome-wide association study comparing lethal PCa cases to cases surviving at least ten years beyond their initial diagnosis. Genotyping was performed with the Affymetrix 5.0 chip (~500,000 single nucleotide polymorphisms (SNPs) and 1483 copy number variants (CNVs)) on DNA from participants in the Physicians’ Health Study and Health Professionals Follow-up Study (196 lethal cases, 368 long-term survivors). After excluding SNPs and individuals based on quality control criteria, logistic regression assuming an additive model was performed using PLINK software.
No SNP reached genome-wide significance (p≤1×10−7), however three independent SNPs had p<1×10−5. One top-ranked SNP replicated (p=0.05) in an independent follow-up study. While no CNV had genome-wide significance, 14 CNVs showed nominal association with PCa mortality (p<0.05).
No variants were significantly associated at a genome-wide level with PCa mortality. Common genetic determinants of lethal PCa are likely to have odds ratios <2.0.
Genetic markers identified could provide biological insight to improve therapy for men with potentially fatal cancer. Larger studies are necessary to detect genetic causes of PCa mortality.
genome scan; prostate cancer; mortality
doxorubicin; nanoparticles; superparamagnetic; TCL-SPION
The role of selenium in prostate cancer (PCa) risk remains controversial, but many epidemiologic studies suggest an inverse association with more aggressive disease. A recently discovered selenoprotein, SEP15, which is highly expressed in the prostate, may play a role either independently or by modifying the effects of selenium.
We genotyped four common single nucleotide polymorphisms (SNPs) capturing common variation (frequency>5%, R2>0.8) within SEP15, as well as rs5859 in the 3′ UTR, previously reported to reduce the efficiency of selenium incorporation into SEP15. We examined the association of these SNPs with PCa risk and PCa-specific mortality, as well as interactions with plasma selenium levels, in the Physicians' Health Study.
In this nested case-control study (1286 cases, 1267 controls), SEP15 polymorphisms were not significantly associated with PCa risk. However, among the cases, three variants were significantly associated with PCa-specific mortality (rs479341 HR=1.94, 95% CI: 1.15, 3.25; rs1407131 HR=2.85, 95% CI: 1.45, 5.59; rs561104 HR=1.54, 95% CI: 1.12, 2.11) with a recessive model. Additionally, rs561104 significantly modified the association of plasma selenium with PCa survival (Pinteraction=0.02); an inverse relationship of high levels of selenium with PCa mortality was apparent only among those without the increased risk genotype.
This study provides evidence that SEP15 genetic variation may influence PCa mortality. Additionally, the association of selenium with PCa mortality was modified by a variant, suggesting the possibility that some men with PCa may benefit more from selenium than others depending on their genotype.
genetic variation; selenium; prostate cancer; survival
BRCA1 functions as a tumor suppressor; recent work suggests that BRCA1 may also induce cell-cycle arrest to allow for DNA repair. We hypothesized that BRCA1 expression in prostate tumor tissue may be associated with prostate cancer progression through regulation of the cell-cycle. We used immunohistochemistry to evaluate BRCA1 protein expression in archival tumors samples from 393 prostate cancer cases in the Physicians' Health Study. The men were followed prospectively from diagnosis to development of metastases and mortality. Fifteen percent of tumors stained positive for BRCA1. BRCA1 positive tumors had substantially increased tumor proliferation index compared to negative tumors (47.0 Ki67 positive nuclei vs. 10.3, p=0.0016), and were more likely to develop lethal cancer compared to BRCA1 negative tumors (Hazard ratio=4.6; 95% Confidence interval: 2.4, 8.7). These findings strengthen the hypothesis that BRCA1 plays a role in cell-cycle control and demonstrate that BRCA1 is a marker of clinical prostate cancer prognosis.
In the United States, 192 000 men were diagnosed as having prostate cancer in 2009, the majority with low-risk, clinically localized disease. Treatment of these cancers is associated with substantial morbidity. Active surveillance is an alternative to initial treatment, but long-term outcomes and effect on quality of life have not been well characterized.
To examine the quality-of-life benefits and risks of active surveillance compared with initial treatment for men with low-risk, clinically localized prostate cancer.
Design and Setting
Decision analysis using a simulation model was performed: men were treated at diagnosis with brachytherapy, intensity-modulated radiation therapy (IMRT), or radical prostatectomy or followed up by active surveillance (a strategy of close monitoring of newly diagnosed patients with serial prostate-specific antigen measurements, digital rectal examinations, and biopsies, with treatment at disease progression or patient choice). Probabilities and utilities were derived from previous studies and literature review. In the base case, the relative risk of prostate cancer–specific death for initial treatment vs active surveillance was assumed to be 0.83. Men incurred short- and long-term adverse effects of treatment.
Hypothetical cohorts of 65-year-old men newly diagnosed as having clinically localized, low-risk prostate cancer (prostate-specific antigen level <10 ng/mL, stage ≤T2a disease, and Gleason score ≤6).
Main Outcome Measure
Quality-adjusted life expectancy (QALE).
Active surveillance was associated with the greatest QALE (11.07 quality-adjusted life-years [QALYs]), followed by brachytherapy (10.57 QALYs), IMRT (10.51 QALYs), and radical prostatectomy (10.23 QALYs). Active surveillance remained associated with the highest QALE even if the relative risk of prostate cancer–specific death for initial treatment vs active surveillance was as low as 0.6. However, the QALE gains and the optimal strategy were highly dependent on individual preferences for living under active surveillance and for having been treated.
Under a wide range of assumptions, for a 65-year-old man, active surveillance is a reasonable approach to low-risk prostate cancer based on QALE compared with initial treatment. However, individual preferences play a central role in the decision whether to treat or to pursue active surveillance.
Gonadotropin-releasing hormone (GnRH) agonists decrease bone mineral density (BMD) and increase fracture risk in men with prostate cancer. Annual zoledronic acid increases BMD in postmenopausal women, but its efficacy in hypogonadal men is not known.
Patients and Methods
In a 12-month study, 40 men with nonmetastatic prostate cancer who were receiving a GnRH agonist and had T scores more than −2.5 were randomly assigned to zoledronic acid (4 mg intravenously on day 1 only) or placebo. BMD of the posteroanterior lumbar spine and proximal femur were measured by dual-energy x-ray absorptiometry.
Mean (± SE) BMD of the posteroanterior lumbar spine decreased by 3.1% ± 1.0% in men assigned to placebo and increased by 4.0% ± 1.0% in men assigned to zoledronic acid (P < .001). BMD of the total hip decreased by 1.9% ± 0.7% in men assigned to placebo and increased by 0.7% ± 0.5% in men assigned to zoledronic acid (P = .004). Similar between-group differences were observed for the femoral neck and trochanter. Serum N-telopeptide, a marker of osteoclast activity, decreased significantly after zoledronic acid treatment.
In men receiving a GnRH agonist, a single treatment with zoledronic acid significantly increased BMD and durably suppressed serum N-telopeptide levels for 12 months. Annual zoledronic acid may be a convenient and effective strategy to prevent bone loss in hypogonadal men.
Therapeutic prostate-specific antigen (PSA) –targeted poxviral vaccines for prostate cancer have been well tolerated. PROSTVAC-VF treatment was evaluated for safety and for prolongation of progression-free survival (PFS) and overall survival (OS) in a randomized, controlled, and blinded phase II study.
Patients and Methods
In total, 125 patients were randomly assigned in a multicenter trial of vaccination series. Eligible patients had minimally symptomatic castration-resistant metastatic prostate cancer (mCRPC). PROSTVAC-VF comprises two recombinant viral vectors, each encoding transgenes for PSA, and three immune costimulatory molecules (B7.1, ICAM-1, and LFA-3). Vaccinia-based vector was used for priming followed by six planned fowlpox-based vector boosts. Patients were allocated (2:1) to PROSTVAC-VF plus granulocyte-macrophage colony-stimulating factor or to control empty vectors plus saline injections.
Eighty-two patients received PROSTVAC-VF and 40 received control vectors. Patient characteristics were similar in both groups. The primary end point was PFS, which was similar in the two groups (P = .6). However, at 3 years post study, PROSTVAC-VF patients had a better OS with 25 (30%) of 82 alive versus 7 (17%) of 40 controls, longer median survival by 8.5 months (25.1 v 16.6 months for controls), an estimated hazard ratio of 0.56 (95% CI, 0.37 to 0.85), and stratified log-rank P = .0061.
PROSTVAC-VF immunotherapy was well tolerated and associated with a 44% reduction in the death rate and an 8.5-month improvement in median OS in men with mCRPC. These provocative data provide preliminary evidence of clinically meaningful benefit but need to be confirmed in a larger phase III study.
The development of chemoradiation – the concurrent administration of chemotherapy and radiotherapy – has led to significant improvements in local tumor control and survival. However, it is limited by its high toxicity. In this study, we report the development of a novel NP (nanoparticle) therapeutic, ChemoRad NP, which can deliver biologically targeted chemoradiation.
A biodegradable and biocompatible lipid–polymer hybrid NP that is capable of delivering both chemotherapy and radiotherapy was formulated.
Using docetaxel, indium111 and yttrium90 as model drugs, we demonstrated that the ChemoRad NP can encapsulate chemotherapeutics (up to 9% of NP weight) and radiotherapeutics (100 mCi of radioisotope per gram of NP) efficiently and deliver both effectively. Using prostate cancer as a disease model, we demonstrated the targeted delivery of ChemoRad NPs and the higher therapeutic efficacy of ChemoRad NPs.
We believe that the ChemoRad NP represents a new class of therapeutics that holds great potential to improve cancer treatment.
biologically targeted nanoparticle; ChemoRad NP; chemoradiation; chemoradiation nanoparticle; nanomedicine; nanotechnology; prostate cancer
To update national risk trends in prostate cancer with a focus on low-risk tumors, to re-examine trends in primary treatment for low-risk tumors, and to attempt to substratify low-risk patients based on pretreatment clinical data.
Materials and Methods
Data were abstracted from the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) registry. 10,385 men were diagnosed between 1990 and 2006 with localized disease. Low risk was defined as a prostate-specific antigen (PSA) level ≤10 ng/mL, a Gleason score ≤6, and a clinical T stage ≤2a. Temporal trends were assessed for patient distribution among risk groups and within the low-risk group for individual risk factors, Kattan nomogram prediction, Cancer of the Prostate Risk Assessment (CAPRA) score, and primary treatment. The ability of the CAPRA score to substratify low-risk prostatectomy patients was evaluated with survival analysis.
The proportion of low-risk tumors in CaPSURE nearly doubled from 27.5% in 1990-1994 to 46.4% in 2000-2001, but has been relatively constant since. A growing proportion of low-risk tumors are cT1c, and virtually all are Gleason score 6. PSA and the percentage of positive biopsies have decreased throughout the study period, as did the mean CAPRA score. The use of active surveillance increased from a nadir of 6.2% in 2000-2001 to 10.2% in 2004-2006. The use of prostatectomy has also increased, whereas use of androgen deprivation and radiation has declined. Likelihood of recurrence increases significantly with rising CAPRA score.
Low-risk patients can be further substratified to identify those at very low-risk based on clinical variables. The use of surveillance is increasing, but overtreatment remains a concern among these patients.
Prostatic neoplasms; Risk factors; Prognosis; Treatment; CAPRA; CaPSURE
The purpose of this study was to evaluate the relationship between the kinetics of PSA decline after androgen deprivation therapy (ADT) initiation and overall survival (OS) in men with metastatic hormone-sensitive prostate cancer (HSPC).
We identified a cohort of metastatic HSPC patients treated with androgen deprivation therapy (ADT) using our institutional database. Patients were included if they had at least 2 serum PSA determinations before nadir PSA and at least one serum PSA value available within 1 month of ADT initiation. Patient characteristics, PSA at ADT initiation, nadir PSA, time to PSA nadir (TTN) and PSA decline (PSAD) in relation to OS were analyzed.
179 patients were identified, with a median follow-up after ADT initiation of 4.0 years. Median OS after ADT initiation was 7.0 years. Median PSA at ADT initiation and PSA nadir were 47 and 0.28 ng/mL, respectively. On univariate analysis: TTN <6 months, a PSAD >52 ng/mL/year, PSA nadir ≥ 0.2 ng/mL, a PSA≥47.2 ng/mL at ADT initiation and Gleason score >7, were associated with a shorter OS. On multivariate analysis, TTN<6 months, Gleason score >7 and a PSA nadir ≥ 0.2 ng/mL independently predicted a shorter OS.
To our knowledge, this is the first report to show that a faster time to reach a PSA nadir post-ADT initiation is associated with shorter survival duration in men with metastatic HSPC. These results need confirmation, but may indicate that a rapid initial response to ADT indicates more aggressive disease.
Prostate cancer; androgen deprivation therapy; hormone-sensitive metastatic prostate cancer; PSA kinetics; Time to PSA nadir
Endostatin inhibits endothelial cell proliferation and migration, prerequisites of angiogenesis. A functional missense mutation (D104N) in endostatin was associated with an increased prostate cancer risk in a small study. We undertook a larger, prospective study within the Physicians’ Health Study to examine D104N and prostate cancer risk and progression among 544 incident prostate cancer cases (1982-1995) and 678 matched controls. The association between endostatin genotype and cancer risk was estimated using logistic regression models. Among cases, Cox models were used to assess D104N and lethal prostate cancer. Given the role of endostatin in neovascularization of adipose tissue, we cross-classified individuals on D104N genotype and body mass index (BMI). The genotype frequency was 1.3% homozygous (NN), 14.5% heterozygous (DN), and 84.2% wildtype homozygous (DD). There was no overall association between carriage of the N allele and prostate cancer risk (RR=1.2, 95% CI: 0.9-1.6) or cancer-specific mortality (HR=1.2, 0.7-1.8). Cases with the polymorphic allele were less likely to be overweight (BMI 25 kg/m2 or greater, 26%) compared to men wildtype homozygous (48%), p<0.0001. Being overweight was associated with a 60% greater prostate cancer risk among those who were wildtype homozygous. In contrast, being overweight was associated a 50% lower risk of cancer among those with the N allele. We did not confirm earlier observation between the D104N polymorphism and prostate cancer. However, our data indicate that prostate cancer cases who carry the variant N allele are more likely to be overweight, and may be more susceptible to the angiogenic influences of obesity in prostate cancer pathogenesis.
Endostatin; angiogenesis; obesity; prostate cancer
In vitro, in vivo, and epidemiologic studies support a role for selenium in reducing the risk of prostate cancer. Our group previously demonstrated a strong interaction between plasma selenium and the manganese superoxide dismutase (SOD2) gene and incident prostate cancer risk. We now hypothesized that SOD2 modifies the association between selenium level and risk of aggressive prostate cancer at diagnosis.
Patients and Methods
We assessed SOD2 variants and plasma selenium in 489 patients with localized/locally advanced prostate cancer from an ongoing retrospective cohort. Cross-sectional associations with aggressive prostate cancer (ie, stage T2b-3, prostate-specific antigen > 10 ng/mL, or biopsy Gleason score ≥ 7) were evaluated using the χ2 test, Cochran-Armitage test for trend, and estimations of relative risk (RR) and 95% CIs.
SOD2 genotype alone was not associated with disease aggressiveness, whereas higher versus lower selenium levels were associated with a slightly increased likelihood of presenting with aggressive disease (RR = 1.35; 95% CI, 0.99 to 1.84). There was evidence of an interaction between SOD2 and selenium levels such that among men with the AA genotype, higher selenium levels were associated with a reduced risk of presenting with aggressive disease (RR = 0.60; 95% CI, 0.32 to 1.12), whereas among men with a V allele, higher selenium levels were associated with an increased risk of aggressive disease (for VV or VA men, RR = 1.82; 95% CI, 1.27 to 2.61; P for interaction = .007).
These data suggest that the relationship between circulating selenium levels at diagnosis and prognostic risk of prostate cancer is modified by SOD2 genotype and indicate caution against broad use of selenium supplementation for men with prostate cancer.
Variants at chromosomal loci 8q24 and 17q are established risk factors for prostate cancer. Many studies have confirmed the findings for risk, but few have examined aggressiveness and other clinical variables in detail. Additionally, Gleason score is typically used as a surrogate for the primary endpoint of prostate cancer mortality. We investigated whether the 8q24 and 17q risk variants are associated with clinical variables as well as prostate cancer mortality.
In the Physicians’ Health Study (1347 cases, 1462 controls), the Dana-Farber Harvard Cancer Center SPORE (Gelb Center) (3714 cases), and the Fred Hutchinson Cancer Research Center King County Case-Control Studies (1308 cases, 1266 controls), we examined eight previously identified 8q24 and 17q risk variants for association with prostate cancer mortality in men of European ancestry. We considered associations with other surrogate markers of prostate cancer aggressiveness such as Gleason score, pathological stage, PSA at diagnosis, and age at diagnosis.
Six of the eight variants were confirmed as prostate cancer risk factors. Several variants were nominally associated with age at diagnosis; when totaling all alleles for SNPs significantly associated with risk, each additional allele decreased age at diagnosis by an average of 6 months in the Physicians’ Health Study (p=0.0005) and 4 months in the Dana-Farber Harvard Cancer Center SPORE (Gelb Center) cohort (p=0.0016). However, there were no statistically significant associations with prostate cancer mortality.
Our results suggest that the 8q24 and 17q prostate cancer risk variants may influence age at diagnosis but not disease aggressiveness.
genetic variation; prostate cancer; mortality
While prostate cancer is a leading cause of cancer death, most men die with and not from their disease, underscoring the urgency to distinguish potentially lethal from indolent prostate cancer. We tested the prognostic value of a previously identified multigene signature of prostate cancer progression to predict cancer-specific death. The Örebro Watchful Waiting Cohort included 172 men with localized prostate cancer of whom 40 died of prostate cancer. We quantified protein expression of the markers in tumor tissue by immunohistochemistry, and stratified the cohort by quintiles according to risk classification. We accounted for clinical parameters (age, Gleason, nuclear grade, tumor volume) using Cox regression, and calculated Receiver Operator Curves to compare discriminatory ability. The hazard ratio of prostate cancer death increased with increasing risk classification by the multigene model, with a 16-fold greater risk comparing highest versus lowest risk strata, and predicted outcome independent of clinical factors (p=0.002). The best discrimination came from combining information from the multigene markers and clinical data, which perfectly classified the lowest risk stratum where no one developed lethal disease; using the two lowest risk groups as referent, the hazard ratio (95% confidence interval) was 11.3 (4.0–32.8) for the highest risk group and difference in mortality at 15 years was 60% (50–70%). The combined model provided greater discriminatory ability (AUC 0.78) than the clinical model alone (AUC 0.71), p=0.04. Molecular tumor markers can add to clinical parameters to help distinguish lethal and indolent prostate cancer, and hold promise to guide treatment decisions.
Enhanced androgen receptor (AR) activity by increased testosterone availability may play important roles in prostate cancer progressing to castration resistant state. Comparison of expression profiles in androgen dependent and independent prostate tumors demonstrated a marked increase of the expression of UDP-glucuronosyltransferase 2B15 (UGT2B15), an androgen catabolic enzyme. We investigated mechanisms controlling the differential expression of UGT2B15 and B17 in response to androgen treatments.
Gene expression was determined by RT-PCR. The association of AR with UGT2B15/B17 genes was determined by Chromatin immuno-precipitation (CHIP). RNA interference was used to knock-down gene expression.
UGT2B15 and B17 genes were not expressed in AR negative prostate cancer cell lines, PC3 and DU145, while they were expressed in AR positive cell lines, LNCaP, LNCaP-abl (an androgen independent LNCaP sub-line), and VCaP. The expression levels of UGT2B15/B17 were up-regulated in LNCaP-abl comparing to those in LNCaP. These results suggest the requirement of AR for the expression of UGT2B15/B17. Treatment with DHT down-regulated the expression of UGT2B15/B17 in LNCaP in a time and dose dependent manner and this down-regulation was competitively antagonized by flutamide and bicalutimide, suggesting a pathway mediated by AR. Further CHIP experiments demonstrated the direct interaction of AR with the promoter regions of UGT2B15/B17 genes. Knocking down AR expression in LNCaP significantly reduced the expression of UGT2B15/B17 and completely inhibited the DHT-induced down-regulation of UGT2B15/B17 genes.
We demonstrated that UGT2B15 and B17 are primary androgen-regulated genes and AR is required for both their basal expression and their androgen-regulated expression.
prostate cancer; androgen; androgen receptor; UGT2B15; UGT2B17
Prostate-specific antigen is a glycoprotein found almost exclusively in normal and neoplastic prostate cells. PSA doubling time, or the change in PSA level over time, has emerged as a useful predictive marker for assessing disease outcome in patients with prostate cancer. It is important to agree on definitions and values for the calculation of PSADT and to develop a common approach to outcome analysis and reporting.
In September 2006 a conference was held at the National Cancer Institute in Bethesda, Maryland to define these parameters and develop guidelines for their use.
The PSA Working Group defined the following criteria regarding PSADT: (1) calculation of PSADT, (2) evidence to support PSADT as a predictive factor in the setting of biochemical recurrence, and (3) use of PSADT as a stratification factor in clinical trials.
We propose that investigators calculate PSADT prior to enrolling patients on clinical studies and calculate it as an additional measurement of therapeutic activity. We believe we have developed practical guidelines for the calculation of PSADT and its use as a measurement of prognosis and outcome. Furthermore, the use of common standards for PSADT in clinical trials is important as we determine which treatments should progress to randomized trials in which “hard” end points such as survival will be employed.
prostate cancer; PSA; consensus; clinical trials; biomarkers