First look at the baseline characteristics of participants in IRONMAN, the international registry for men with advanced prostate cancer

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Background: Patients with advanced prostate cancer (APC) experience high mortality and increasingly deteriorating quality of life due to the disease itself and the therapies they are treated with. Despite recent advances in the treatment landscape, disparities in outcomes have only worsened. There is an urgent need to identify disparities in treatment patterns and outcomes in advanced disease in diverse populations. The International Registry for Men with Advanced Prostate Cancer (IRONMAN) is uniquely equipped to address these needs. Methods: IRONMAN is a prospective registry initiated in 2017 with a planned accrual of 5000 patients with newly diagnosed metastatic hormone-sensitive (mHSPC) and castration-resistant (CRPC) prostate cancer. As of 10/11/2022, 2890 patients have enrolled from 14 countries at 113 sites, with 2 more countries pending activation. Sites were selected to create a diverse cohort across race/ethnicity, geography and socioeconomic factors. Patients are followed for survival, clinically significant adverse events, changes in cancer treatments, biomarkers, and Patient-Reported Outcome Measures (PROMs). This analysis includes patients with treatment data reported from Baseline through Month 3 as of October 2021 (n=1931, 9 countries). Results: Patients were recruited across the USA (N=799), Australia (146), Canada (282), Spain (238), England (205), and all other countries (261). 61% had mHSPC, and 39% had CRPC at enrollment with little variation in these proportions across countries. Based on self-report, 87% of patients were White, 9% Black, 4% reported other races/ethnicities, and 353 did not report race. In the US, 18% of patients were Black. Globally, 22% of respondents reported current or former military service. The most common first systemic therapy on study was androgen receptor signaling inhibitors (ARSI) +/- ADT in 1039 (54%), ranging between 12% and 66% of patients by country. 19% received chemotherapy +/- ADT and 18% received ADT alone. ARSI use varied by age, race, and metastatic disease site. Conclusions: Our preliminary results highlight our ability to successfully enroll and follow APC patients from 113 sites across 14 countries, with 2890 of 5000 planned patients enrolled. Accrual is greater in de novo mHSPC patients than anticipated. Differences in treatment patterns are already emerging, with more ARSI use in the mHSPC setting in North America than other regions. Our data demonstrates that IRONMAN participating sites are rapidly adopting new treatment recommendations into clinical practice of real-world patients.

Abstract 3354: A gene expression signature of high serum cholesterol and prostate cancer outcomes

Statin use is associated with reduced risk of lethal prostate cancer potentially through effects on serum cholesterol. Using data from a prospective study with measured serum cholesterol among men subsequently diagnosed with prostate cancer, we developed a tumour gene expression score to reflect the pre-diagnosis serum cholesterol environment these tumours developed in, and applied this score to a separate study to examine the relationship with prostate cancer-specific outcomes. We identified 127 men with prostate cancer in the prospective Health Professionals Follow-up Study, whose prostate tumors underwent whole genome gene expression profiling. Pre-diagnosis serum cholesterol was measured a median of 3.3 years (IQR 1.5-4.8 years) prior to cancer diagnosis. We excluded men using statins either at time of blood draw for serum cholesterol measurement or at cancer diagnosis. Using tumor biopsy whole genome transcriptomic data from 232 prostate cancer patients treated with radiotherapy in Northern Ireland (NI), we generated the serum cholesterol score by summing z-score-transformed expression for each gene. PTEN status was measured using a published 50-gene transcriptional signature. Both signatures were dichotomized using the median cut-point. Age-adjusted and multivariable Cox regression analysis was used to compute HRs and 95% CI for associations of the cholesterol gene score with biochemical recurrence and metastasis risk. We identified in HPFS a set of 30 genes associated with pre-diagnostic serum cholesterol with a fold change ≥4 which included PTEN. In the NI Cohort, tumors with above median cholesterol scores had higher expression of the PTEN-null signature (p<0.001). Increased serum cholesterol tumor score was associated with higher Gleason grade (p<0.001); this relationship was stronger in PTEN-null tumours relative to PTEN-intact. Over a median follow-up of 11 years, 68 men experienced biochemical recurrence, and 28 developed metastasis. In age-adjusted analysis, patients with high serum cholesterol score had increased risk of recurrence (HR 1.84; 95% CI 1.13-2.99) and metastasis (HR 1.98; 95% CI 0.91-4.29), though the latter was not statistically significant. Associations with recurrence and metastasis were attenuated following further adjustment for Gleason score (HR 1.65; 95% CI, 0.98-2.77 and HR 1.49; 95% CI 0.66-3.35, respectively). Men with increased tumor gene expression of a serum cholesterol score, derived to reflect tumor development within a high serum cholesterol environment, were more likely to be diagnosed with a PTEN-null prostate cancer. These men had more aggressive prostate cancer at diagnosis and increased risk of recurrence, particularly men with PTEN-null disease. Our results support recent findings showing a reduced risk of PTEN-null prostate cancer in statin users, and inform our understanding of the potential role of serum cholesterol in prostate cancer etiology.

Citation Format: Sarah Jane Winter, Sophia R. Halliday, Travis A. Gerke, Lorelei Ann Mucci, Konrad H. Stopsack, Gillian Prue, Suneil Jain, Emma H. Allott. A gene expression signature of high serum cholesterol and prostate cancer outcomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3354.

BRCAAWAY: A randomized phase 2 trial of abiraterone, olaparib, or abiraterone + olaparib in patients with metastatic castration-resistant prostate cancer (mCRPC) with DNA repair defects

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Background: The PARP-inhibitor olaparib is approved for mCRPC patients (pts) with deleterious germline or somatic homologous recombination repair gene mutations (HRRm). PARP1 interacts with androgen signaling, and castration-resistant tumor cells exhibit increased PARP1 activity. Preclinically PARP1-inhibition synergizes with androgen receptor (AR) targeted therapy. BRCAAway is a biomarker selected, randomized, open-label, multicenter phase 2 trial evaluating efficacy of targeting AR vs PARP vs combination in first line mCRPC patients with germline and/or somatic HRRm in BRCA1, BRCA2, or ATM. Methods: Eligible mCRPC pts underwent tumor next generation sequencing and germline testing. Pts with inactivating BRCA1, BRCA2 and/or ATM alterations were randomized 1:1:1 to Arm 1 abiraterone (1000 mg daily) + prednisone (5mg bid) (Abi/pred), Arm 2 olaparib (300 mg bid) or Arm 3 olaparib + Abi/pred. The primary end point is progression-free survival (PFS) analyzed using Kaplan-Meier estimates and Cox regression. Secondary endpoints include measurable disease response rate (RR) by RECIST, PSA-RR, undetectable PSA (≤ 0.2 ng/ml) and toxicity. Arms 1 and 2 pts were allowed to cross over at progression. Pts with other HRRm were treated with olaparib; Arm 4 (ongoing). Results: 161 pts were registered and had NGS testing; 60 pts were randomized to Arms 1-3; to date 59 are evaluable for toxicity and 53 are evaluable for PFS. Baseline median age 67 (range 42-85) years; 54 pts were White, 6 were Black; sites of disease: bone only (n=31), soft tissue only (n=18), bone and soft tissue (n=10); median PSA 14.61 ng/ml (range 0.15-4036.8). Mutational status: BRCA1 only n = 2, BRCA2 only n = 39, ATM only n = 8, and > 1 HRRm n = 11. 34 pts had germline and 26 had somatic mutations. Median (range) follow-up time: 8.3 (0.8, 33.3), 12.2 (2.7, 21.8) and 16.8 (2.9, 41.7) months in Arms 1, 2 and 3. 43 pts had treatment-related adverse events; most common were fatigue (23 pts; 1 Grade (G) 3, 22 G1/2), nausea (17 pts, G1/2), and anemia (9 pts, 2 G3, 7 G1/2). ≥50% PSA decline was 79%, 67%, and 85% of pts in Arms 1, 2, and 3, respectively. Median PSA nadir (ng/mL) (95% CI) Arms 1-3: 2.17 (0.44, 49.27), 3.10 (0.83, 12.01), and 0.50 (0.10, 2.13), respectively. Undetectable PSA, median PFS, and 12-month PFS by Arm are listed in the table. Conclusions: In mCRPC pts with inactivating BRCA1, BRCA2 and/or ATM alterations Abi/pred + olaparib was well tolerated and resulted in longer PFS and better PSA response vs either agent alone. Clinical trial information: NCT03012321. [Table: see text]

First look at patient reported outcomes from IRONMAN, the international registry of men with advanced prostate cancer

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Background: While population-based estimates of advanced prostate cancer survivors are lacking, an estimated 180,000 men in the US are living with metastatic prostate cancer. Their survivorship experience is distinct from localized patients as they suffer quality of life detriments both due to the severity of disease and its therapies. We examined quality-of-life indictors among men in the IRONMAN global registry of advanced prostate cancer. Methods: IRONMAN (International Registry of Men with Advanced Prostate Cancer) is a population-based prospective study of men with newly diagnosed advanced, metastatic hormone-sensitive (mHSPC) and castration-resistant prostate cancer (CRPC) enrolled from 16 countries. We report data from first 1865 men enrolled, 1567 who completed a baseline Patient Reported Outcome Measure (PROM) in the US (N=581), Canada (N=245), Spain (N=166), UK (N=204), Australia (N=126), Switzerland (N=88), Sweden (N=70), Ireland (N=46), and Brazil (N=41). PROMs are collected at baseline and every three months using electronic (90%) or paper versions of validated questionnaires. Results: The cohort includes 1,128 men with mHSPC and 737 with CRPC. Based on self-report, 9% of men overall (18% in the US) are Black and 83% are white (78% in the US). Sleep problems were common among men at enrollment, with 59% of men reporting problems with insomnia. The prevalence was similarly high among men with mHSPC or CRPC disease. Ten percent of men reported that pain substantially interfered with daily activities, and 24% reported pain had some effect. Physical functioning was high among both mHSPC (median 93.3, 80-100) and CRPC (median 86.7, 73.3-100) patients based on EORTC QLQ-30. Global health status was similar between the two groups (median 75, 58.3 - 83.3). More than 25% of men reported some cognitive impairment at baseline. Financial difficulties due to the disease and treatment were quite high, ranging from 12% in Sweden, 16% in Canada and Spain, 34% in the US, and 46% in Brazil. Conclusions: Men with advanced prostate cancer experience a range of quality of life detriments which impair overall health. While at baseline, many of these measures were similar among men with mHSPC and CRPC, we will continue to monitor these over time to examine changes in quality of life associated with disease progression and treatments. A longer-term goal is to identify opportunities for intervention to improve quality of life and potentially improve survival. Clinical trial information: NCT03151629.

IRONMAN: The international registry for men with advanced prostate cancer

TPS190

Background: Men with advanced prostate cancer (APC) experience high mortality and severely impacted quality of life due to the disease itself as well as its therapies, with Black men facing the highest disease burden. The treatment landscape for APC is rapidly changing; however, little is known about the real-life experience of men receiving new therapies. There is an urgent need to identify disparities in treatment patterns and outcomes in advanced disease, based on patient and country demographics. The International Registry for Men with Advanced Prostate Cancer (IRONMAN) is uniquely equipped to meet these needs. Methods: IRONMAN is a population-based prospective cohort of men with newly diagnosed metastatic hormone-sensitive (mHSPC) and castration-resistant (CRPC) prostate cancer aiming to enroll 5,000 men across 16 countries (Australia, the Bahamas, Barbados, Brazil, Canada, Ireland, Jamaica, Kenya, Nigeria, Norway, South Africa, Spain, Sweden, Switzerland, United Kingdom, Untied States). Patients are followed prospectively for overall survival, clinically significant adverse events, changes in cancer treatments, biomarkers, and Patient-Reported Outcome Measures (PROMs). Data is collected via longitudinal electronic questionnaires from patients and providers as well as blood samples and medical records. IRONMAN is currently enrolling in 10 countries at 103 sites. Sites were selected to create a diverse cohort across race/ethnicity, rural/urban populations, socioeconomic factors, and geographic regions. Of the first 1,865 men enrolled to date, 60% have mHSPC and 40% have CRPC; overall, 9% of men (18% in the US) self-identify as Black and 82% identify as white (78% in the US). 60% (N = 1,111) of this cohort has been enrolled outside of the US, and the median age at study entry is 70 years. The distribution and demographics of patients are continuously monitored to inform ongoing enrollment efforts. The IRONMAN Diversity Working Group meets monthly to discuss barriers and strategies to enhance enrollment of a racially and ethnically diverse population. The Low- and Middle-Income Country Working Group addresses the unique needs of men being recruited from the Caribbean and African sites in addition to supporting broad oncology efforts in these regions. These efforts support IRONMAN’s larger goal to investigate disparities in the care of patients with APC, having potential implications for decreasing racial disparities in survival outcomes. Clinical trial information: NCT03151629.

Prognostic and therapeutic significance of COP9 signalosome subunit CSN5 in prostate cancer

Chromosome 8q gain is associated with poor clinical outcomes in prostate cancer, but the underlying biological mechanisms remain to be clarified. CSN5, a putative androgen receptor (AR) partner that is located on chromosome 8q, is the key subunit of the COP9 signalosome, which deactivates ubiquitin ligases. Deregulation of CSN5 could affect diverse cellular functions that contribute to tumor development, but there has been no comprehensive study of its function in prostate cancer. The clinical significance of CSN5 amplification/overexpression was evaluated in 16 prostate cancer clinical cohorts. Its oncogenic activity was assessed by genetic and pharmacologic perturbations of CSN5 activity in prostate cancer cell lines. The molecular mechanisms of CSN5 function were assessed, as was the efficacy of the CSN5 inhibitor CSN5i-3 in vitro and in vivo. Finally, the transcription cofactor activity of CSN5 in prostate cancer cells was determined. The prognostic significance of CSN5 amplification and overexpression in prostate cancer was independent of MYC amplification. Inhibition of CSN5 inhibited its oncogenic function by targeting AR signaling, DNA repair, multiple oncogenic pathways, and spliceosome regulation. Furthermore, inhibition of CSN5 repressed metabolic pathways, including oxidative phosphorylation and glycolysis in AR-negative prostate cancer cells. Targeting CSN5 with CSN5i-3 showed potent antitumor activity in vitro and in vivo. Importantly, CSN5i-3 synergizes with PARP inhibitors to inhibit prostate cancer cell growth. CSN5 functions as a transcription cofactor to cooperate with multiple transcription factors in prostate cancer. Inhibiting CSN5 strongly attenuates prostate cancer progression and could enhance PARP inhibition efficacy in the treatment of prostate cancer.

Extent, impact, and mitigation of batch effects in tumor biomarker studies using tissue microarrays

Tissue microarrays (TMAs) have been used in thousands of cancer biomarker studies. To what extent batch effects, measurement error in biomarker levels between slides, affects TMA-based studies has not been assessed systematically. We evaluated 20 protein biomarkers on 14 TMAs with prospectively collected tumor tissue from 1448 primary prostate cancers. In half of the biomarkers, more than 10% of biomarker variance was attributable to between-TMA differences (range, 1–48%). We implemented different methods to mitigate batch effects (R package batchtma), tested in plasmode simulation. Biomarker levels were more similar between mitigation approaches compared to uncorrected values. For some biomarkers, associations with clinical features changed substantially after addressing batch effects. Batch effects and resulting bias are not an error of an individual study but an inherent feature of TMA-based protein biomarker studies. They always need to be considered during study design and addressed analytically in studies using more than one TMA.

To understand cancer, researchers need to know which molecules tumor cells use. These so-called ‘biomarkers’ tag cancer cells as being different from healthy cells, and can be used to predict how aggressive a tumor may be, or how well it might respond to treatment.

A popular technique for assessing biomarkers across multiple tumors is to use tissue microarrays. This involves taking samples from different tumors and embedding them in a block of wax, which is then cut into micro-thin slices and stained with reagents that can detect specific biomarkers, such as proteins. Each block contains hundreds of samples, which all experience the same conditions. So, any patterns detected in the staining are likely to represent real variations in the biomarkers present.

Many cancer studies, however, often compare samples from multiple tissue microarrays, which may increase the risk of technical artifacts: for example, staining may look stronger in one batch of tissue samples than another, even though the amount of biomarker present in these different arrays is roughly the same. These ‘batch effects’ could potentially bias the results of the experiment and lead to the identification of misleading patterns.

To evaluate how batch effects impact tissue microarray studies, Stopsack et al. examined 14 wax blocks which contained tumor samples from 1,448 men with prostate cancer. This revealed that for some biomarkers, but not others, there were noticeable differences between tissue microarrays that were clearly the result of batch effects. Stopsack et al. then tested six different ways of fixing these discrepancies using statistical methods. All six approaches were successful, even if the arrays included tumors with different characteristics, such as tumors that had been diagnosed more or less recently.

This work highlights the importance of considering batch effects when using tissue microarrays to study cancer. Stopsack et al. have used their statistical approaches to develop freely available software which can reduce the biases that sometimes arise from these technical artifacts. This could help researchers avoid misleading patterns in their data and make it easier to detect real variations in the biomarkers present between tumor samples.

Dynamic expression of SNAI2 in prostate cancer predicts tumor progression and drug sensitivity

Prostate cancer is a highly heterogeneous disease, understanding the crosstalk between complex genomic and epigenomic alterations will aid in developing targeted therapeutics. We demonstrate that, even though snail family transcriptional repressor 2 (SNAI2) is frequently amplified in prostate cancer, it is epigenetically silenced in this disease, with dynamic changes in SNAI2 levels showing distinct clinical relevance. Integrative clinical data from 18 prostate cancer cohorts and experimental evidence showed that gene fusion between transmembrane serine protease 2 (TMPRSS2) and ETS transcription factor ERG (ERG) (TMPRSS2–ERG fusion) is involved in the silencing of SNAI2. We created a silencer score to evaluate epigenetic repression of SNAI2, which can be reversed by treatment with DNA methyltransferase inhibitors and histone deacetylase inhibitors. Silencing of SNAI2 facilitated tumor cell proliferation and luminal differentiation. Furthermore, SNAI2 has a major influence on the tumor microenvironment by reactivating tumor stroma and creating an immunosuppressive microenvironment in prostate cancer. Importantly, SNAI2 expression levels in part determine sensitivity to the cancer drugs dasatinib and panobinostat. For the first time, we defined the distinct clinical relevance of SNAI2 expression at different disease stages. We elucidated how epigenetic silencing of SNAI2 controls the dynamic changes of SNAI2 expression that are essential for tumor initiation and progression and discovered that restoring SNAI2 expression by treatment with panobinostat enhances dasatinib sensitivity, indicating a new therapeutic strategy for prostate cancer.

A prospective study of inflammatory biomarkers and growth factors and risk of glioma in the UK Biobank

PURPOSE

The role of growth factors and inflammation in the onset of glioma is poorly understood, and conflicting reports of associations of circulating IGF-1 and inflammatory biomarkers with glioma risk exist in the literature. We examined associations between C-reactive protein (CRP), white blood cell count (WBC), neutrophil-to-lymphocyte ratio (NLR), and insulin-like growth factor-1 (IGF-1) and glioma risk in the UK Biobank cohort.

METHODS

Hazard ratios (HR) and 95% confidence intervals (CI) for glioma according to circulating biomarkers concentrations were calculated using Cox proportional hazards regression, adjusted for age, sex, race, and education. Analyses were conducted separately for glioma overall and by glioma subtype.

RESULTS

We identified 417 incident glioma cases among 428,537 participants with 3,255,815 person-years of follow up. Weak, non-significant associations were observed with increasing levels of these biomarkers for risk of glioma overall or by glioma subtype. Among women only, IGF-1 in the highest quartile was positively associated with glioma risk compared to the lowest quartile (HR=1.64, 95%CI: 1.03-2.60, p-trend=0.08), as was NLR (HR=1.54, 95%CI: 1.00-2.39, p-trend=0.05).

CONCLUSION

In this prospective cohort, we found no significant associations between the inflammatory biomarkers CRP and WBC and the development of glioma. NLR and IGF-1 were associated with risk in women, but not men. When considered with previous studies, further investigation of NLR and IGF-1 as markers of glioma risk appears warranted, particularly in women.

Abstract 863: Circadian gene expression in metastatic sites and association with survival in metastatic castration-resistant prostate cancer

Introduction: In experimental and epidemiological studies, alterations in several core circadian genes at the germline and tumor level have been associated with prostate cancer. The aim of this study was to investigate mRNA expression of circadian related genes in men with metastatic castration-resistant prostate cancer (mCRPC), and the association with survival.

Methods: We assessed whole exome and RNA sequencing data from 317 mCRPC patients from the Stand Up to Cancer-Prostate Cancer Foundation (SU2C-PCF) database. Data were obtained from six sites: metastasis to bone (n=107; n=65 deaths), lymph node (n=129; n=88 deaths), liver (n=42; n=35 deaths), lung (n=6; n=3 deaths), and other soft tissue (n=26; n=20 deaths), as well as primary prostate (n=7; n=5 deaths) over a median follow-up of 71.8 months. We evaluated expression of twelve core circadian genes (ARNTL, CLOCK, CRY1, CRY2, CSNK1E, NR1D1, NPAS2, PER1, PER2, PER3, RORA, TIMELESS) as transcripts per million (TPM). We used the correlation of correlations method to estimate inter-gene correlations between tissue. Unpaired Wilcoxon rank sum tests compared circadian expression differences with tumor mutations in AR and p53, two of the most common genomic alterations in mCRPC. We conducted multivariable Cox regression, overall and stratified by tissue type, to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs) for expression (modeled continuously) and overall survival, adjusted for age and PSA at diagnosis, Gleason, treatment, and histology.

Results: Many genes showed low or negative correlation across tissues, with the greatest discordance in CSNK1E (μICC=0.10), and greatest concordance in TIMELESS (μICC=0.55). Lower expression of ARNTL was found in patients with alterations to both p53 and AR. Similarly, higher expression of PER2 and RORA was found in AR-/p53+, compared to those AR+ and AR-/p53-. Higher expression of TIMELESS was associated with risk of death overall and across all tissue sites (HRoverall: 1.02, 95% CI: 1.01-1.03). In liver, higher expression of CLOCK (HR: 0.22, 95% CI: 0.07 - 0.71) and CSNK1E (HR: 0.87, 95% CI: 0.76 - 1.00), and lower expression of CRY1 (HR: 1.62, 95% CI: 1.16 - 2.26) was associated with a lower risk of death. Higher expression of CRY2 (HR: 1.25, 95% CI: 1.02 - 1.53) in liver, but lower expression in bone (HR: 0.95, 95% CI: 0.90 - 1.00) was associated with an increased risk of death. We found no association between ARNTL, NR1D1, NPAS2, PER3, or RORA and survival in any metastatic site.

Conclusion: Our results show that circadian gene expression is altered in tissue from mCRPC patients, with substantial heterogeneity in circadian related expression patterns between metastatic tissue sites. These results support prior research on the role of circadian gene expression, particularly CRY1 and CLOCK, and outcomes in localized prostate cancer.

Citation Format: Benjamin D. Booker, Konrad H. Stopsack, Travis A. Gerke, Kathryn Penny, Philip W. Kantoff, Lorelei A. Mucci, Sarah C. Markt, PCF/SU2C International Prostate Cancer Dream Team. Circadian gene expression in metastatic sites and association with survival in metastatic castration-resistant prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 863.

Molecular Determinants of Thyroid Nodules with Indeterminate Cytology and RAS Mutations

Background:RAS gene family mutations are the most prevalent in thyroid nodules with indeterminate cytology and are present in a wide spectrum of histological diagnoses. We evaluated differentially expressed genes and signaling pathways across the histological/clinical spectrum of RAS-mutant nodules to determine key molecular determinants associated with a high risk of malignancy. Methods: Sixty-one thyroid nodules with RAS mutations were identified. Based on the histological diagnosis and biological behavior, the nodules were grouped into five categories indicating their degree of malignancy: non-neoplastic appearance, benign neoplasm, indeterminate malignant potential, low-risk cancer, or high-risk cancer. Gene expression profiles of these nodules were determined using the NanoString PanCancer Pathways and IO 360 Panels, and Angiopoietin-2 level was determined by immunohistochemical staining. Results: The analysis of differentially expressed genes using the five categories as supervising parameters unearthed a significant correlation between the degree of malignancy and genes involved in cell cycle and apoptosis (BAX, CCNE2, CDKN2A, CDKN2B, CHEK1, E2F1, GSK3B, NFKB1, and PRKAR2A), PI3K pathway (CCNE2, CSF3, GSKB3, NFKB1, PPP2R2C, and SGK2), and stromal factors (ANGPT2 and DLL4). The expression of Angiopoietin-2 by immunohistochemistry also showed the same trend of increasing expression from non-neoplastic appearance to high-risk cancer (p < 0.0001). Conclusions: The gene expression analysis of RAS-mutant thyroid nodules suggests increasing upregulation of key oncogenic pathways depending on their degree of malignancy and supports the concept of a stepwise progression. The utility of ANGPT2 expression as a potential diagnostic biomarker warrants further evaluation.

Accessible Pipeline for Translational Research Using TCGA: Examples of Relating Gene Mechanism to Disease-Specific Outcomes

Bioinformatic scientists are often asked to do widespread analyses of publicly available datasets in order to identify genetic alterations in cancer for genes of interest; therefore, we sought to create a set of tools to conduct common statistical analyses of The Cancer Genome Atlas (TCGA) data. These tools have been developed in response to requests from our collaborators to ask questions, validate findings, and better understand the function of their gene of interest. We describe here what data we have used, how to obtain it, and what figures we have found useful.

Multiplex Immunofluorescence in Formalin-Fixed Paraffin-Embedded Tumor Tissue to Identify Single-Cell-Level PI3K Pathway Activation

PURPOSE

Identifying cancers with high PI3K pathway activity is critical for treatment selection and eligibility into clinical trials of PI3K inhibitors. Assessments of tumor signaling pathway activity need to consider intratumoral heterogeneity and multiple regulatory nodes.

EXPERIMENTAL DESIGN

We established a novel, mechanistically informed approach to assessing tumor signaling pathways by quantifying single-cell-level multiplex immunofluorescence using custom algorithms. In a proof-of-concept study, we stained archival formalin-fixed, paraffin-embedded (FFPE) tissue from patients with primary prostate cancer in two prospective cohort studies, the Health Professionals Follow-up Study and the Physicians' Health Study. PTEN, stathmin, and phospho-S6 were quantified on 14 tissue microarrays as indicators of PI3K activation to derive cell-level PI3K scores.

RESULTS

In 1,001 men, 988,254 tumor cells were assessed (median, 743 per tumor; interquartile range, 290-1,377). PI3K scores were higher in tumors with PTEN loss scored by a pathologist, higher Gleason grade, and a new, validated bulk PI3K transcriptional signature. Unsupervised machine-learning approaches resulted in similar clustering. Within-tumor heterogeneity in cell-level PI3K scores was high. During long-term follow-up (median, 15.3 years), rates of progression to metastases and death from prostate cancer were twice as high in the highest quartile of PI3K activation compared with the lowest quartile (hazard ratio, 2.04; 95% confidence interval, 1.13-3.68).

CONCLUSIONS

Our novel pathway-focused approach to quantifying single-cell-level immunofluorescence in FFPE tissue identifies prostate tumors with PI3K pathway activation that are more aggressive and may respond to pathway inhibitors.

Abstract 3520: Immunogenomic landscape of grade group 5 prostate cancer predicts risk of lethal outcomes and may inform treatment response

Introduction

Prognostic and therapeutic implications of the immunogenomic landscape in poorly differentiated Grade Group 5 (GG5) prostate cancer (PCa) remains largely unknown. While novel treatment strategies including immuno-radiotherapy have been hypothesized to attenuate disease progression in advanced PCa, limited data exist to show underlying mechanisms related to immunogenomcis and its role in the management of GG5 PCa.

Method

This retrospective analysis includes 822 PCa patients who underwent radical prostatectomy (RP) with pathologic GG5 disease. Immunogenomic interaction between the immune content score (ICS) and Decipher score was used to predict the metastasis and Prostate cancer specific mortality (PCSM). Immunogenomic interaction categories were used to assess patient response to radiation therapy, measured by the PORTOS score. Additionally, 135 biopsy based tumor samples were also used to validate the immunogenomic correlation between ICS and Decipher as well as the association with PORTOS score. A Kruskal-Wallis test was used to compare median scores whereas methods of survival analysis were used for time dependent endpoints. Principal component analysis (PCA) was used to show sample clustering based on PORTOS score.

Results

Among GG5 patients 64.8% had high Decipher risk score (&gt; 0.60) whereas 35.5% had low-average risk score (≤ 0.60). When comparing Decipher risk categories with ICS, a linear association was observed with the highest ICS quartile showing the highest Decipher score (Spearman's correlation 0.23, p &lt; 2.4e−11). In a multivariable model, high Decipher score was associated with risk metastasis (HR = 1.63, 95% CI: 1.12 - 2.37, p = 0.01) and PCSM (HR = 1.61, 95% CI: 0.93 – 2.78, p = 0.08) whereas high ICS did not show significant effect on lethal outcomes. However, in the interaction model, effect of decipher on lethal outcomes was augmented in relation with higher ICS. Patients with ICSHigh and DecipherHigh showed significantly higher risk of metastasis (HR = 3.29, 95% CI: 1.53 - 7.07, p = 0.002) and PCSM (HR = 4.15, 95% CI: 1.55 - 11.0, p = 0.004). Additionally, ICSHigh and DecipherHigh also showed higher PORTOS score compared to those with ICSLow and DecipherLow (p &lt; 2.2e−16). Similar to RP cases, in the validation biopsy data Decipher score and ICS were associated (p = 0.01). Likewise, the association of immunogenomic categories with PORTOS score was also consistent in the validation dataset (p = 0.0002). PCA in both RP and validation data using other T cells (i.e. CD4+, CD8+ and Treg) along with ICS, showed separation of high and low PORTOS score categories in relation to immune cells.

Conclusions

The immunogenomic landscape of GG5 disease has major prognostic and therapeutic implications in aggressive PCa. Immunogenomic interaction between immune content and genomic risk classifiers can be used to identify subsets of patients who are at increased risk of metastasis and PCSM, and may have enhanced response to radiotherapy.

Citation Format: Kosj Yamoah, Shivanshu Awasthi, Brandon Mahal, Shuang G. Zhao, Julieta Abraham-Miranda, Travis A. Gerke, Elai Davicioni, Robert J. Rounbehler, Anders E. Berglund, Daniel G. Grass, Jong Y. Park, Julio M. Pow-Sang, Daniel Fernandez, Rohit K. Jain, Edward M. Schaeffer, Stephen Freedland, Daniel E. Spratt, Robert B. Den, Manish Kohli, Timothy R. Rebbeck, Felix Y. Fang. Immunogenomic landscape of grade group 5 prostate cancer predicts risk of lethal outcomes and may inform treatment response [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3520.

Baldness and Risk of Prostate Cancer in the Health Professionals Follow-up Study

BACKGROUND

The association between male pattern baldness and prostate cancer has been inconsistent. We prospectively investigated the association between baldness at age 45 and prostate cancer risk in the Health Professionals Follow-up Study (HPFS), focusing on clinical and molecular markers.

METHODS

Baldness was self-reported on the 1992 questionnaire using the modified Norwood-Hamilton scale prior to diagnosis. We estimated HRs between baldness and prostate cancer risk among 36,760 men, with follow-up through 2014. We also investigated whether baldness was associated with prostate cancer defined by tumor protein expression of androgen receptor and the presence of the TMPRSS2:ERG fusion.

RESULTS

During 22 years, 5,157 prostate cancer cases were identified. Fifty-six percent of the men had either frontal or vertex baldness. No significant associations were found between baldness and prostate cancer risk. Among men younger than 60 years, there was a statistically significant association between frontal and severe vertex baldness and overall prostate cancer (HR: 1.74; 95% confidence interval: 1.23-2.48). Baldness was not significantly associated with expression of molecular subtypes defined by AR and TMPRSS2:ERG IHC of prostate tumors.

CONCLUSIONS

This study showed no association between baldness at age 45 and prostate cancer risk, overall or for clinical or molecular markers. The association between baldness and overall prostate cancer among younger men is intriguing, but caution is warranted when interpreting this finding.

IMPACT

The null findings from this large cohort study, together with previous literature's inconclusive findings across baldness patterns, suggest that baldness is not a consistent biomarker for prostate cancer risk or progression.

Prostate-specific antigen dynamics predict individual responses to intermittent androgen deprivation

Intermittent androgen deprivation therapy (IADT) is an attractive treatment for biochemically recurrent prostate cancer (PCa), whereby cycling treatment on and off can reduce cumulative dose and limit toxicities. We simulate prostate-specific antigen (PSA) dynamics, with enrichment of PCa stem-like cell (PCaSC) during treatment as a plausible mechanism of resistance evolution. Simulated PCaSC proliferation patterns correlate with longitudinal serum PSA measurements in 70 PCa patients. Learning dynamics from each treatment cycle in a leave-one-out study, model simulations predict patient-specific evolution of resistance with an overall accuracy of 89% (sensitivity = 73%, specificity = 91%). Previous studies have shown a benefit of concurrent therapies with ADT in both low- and high-volume metastatic hormone-sensitive PCa. Model simulations based on response dynamics from the first IADT cycle identify patients who would benefit from concurrent docetaxel, demonstrating the feasibility and potential value of adaptive clinical trials guided by patient-specific mathematical models of intratumoral evolutionary dynamics.

A prospective study of coffee and tea consumption and the risk of glioma in the UK Biobank

BACKGROUND

Coffee and tea have been hypothesised to reduce the risk of some cancers; however, their impact on glioma is less well studied.

METHODS

We examined associations between self-reported intake of tea and coffee in relation to glioma risk in the UK Biobank. We identified 487 incident glioma cases among 379,259 participants. Hazard ratios (HR) and 95% confidence intervals (CI) for glioma according to caffeinated beverage consumption were calculated using Cox proportional hazards regression with adjustment for age, gender, race and education; daily cups of tea or coffee were included in models considering the other beverage.

RESULTS

Consuming 4 or more cups of tea was associated with reduced risk of glioma when compared to no tea consumption (HR = 0.69; 95% CI, 0.51-0.94). A significant inverse association was observed for glioblastoma (HR = 0.93 per 1 cup/d increment; 95% CI, 0.89-0.98) and among males for all gliomas combined (HR = 0.95 per 1 cup/d increment; 95% CI, 0.90-1.00). A suggestive inverse association was also observed with greater consumption of coffee (HR = 0.71; 95% CI, 0.49-1.05 for >4 versus 0 cups/d). Results were not materially changed with further adjustment for smoking, alcohol and body mass index. Associations were similar in 2-year and 3-year lagged analyses.

CONCLUSIONS

In this prospective study, we found a significant inverse association between tea consumption and the risk of developing glioma, and a suggestive inverse association for the consumption of coffee. Further investigation on the possible preventive role of caffeine in glioma is warranted.

Statin Use Is Associated with Lower Risk of PTEN-Null and Lethal Prostate Cancer

PURPOSE

Statins are associated with lower risk of aggressive prostate cancer, but lethal prostate cancer is understudied and contributing mechanisms are unclear. We prospectively examined statins and lethal prostate cancer risk in the Health Professionals Follow-up Study (HPFS), tested associations with molecular subtypes, and integrated gene expression profiling to identify putative mechanisms.

EXPERIMENTAL DESIGN

Our study included 44,126 men cancer-free in 1990, followed for prostate cancer incidence through 2014, with statin use recorded on biennial questionnaires. We used multivariable Cox regression to examine associations between statins and prostate cancer risk overall, by measures of clinically significant disease, and by ERG and PTEN status. In an exploratory analysis, age-adjusted gene set enrichment analysis identified statin-associated pathways enriched in tumor and adjacent normal prostate tissue.

RESULTS

During 24 years of follow-up, 6,305 prostate cancers were diagnosed and 801 (13%) were lethal (metastatic at diagnosis or metastatic/fatal during follow-up). Relative to never/past use, current statin use was inversely associated with risk of lethal prostate cancer [HR, 0.76; 95% confidence interval (CI), 0.60-0.96] but not overall disease. We found a strong inverse association for risk of PTEN-null cancers (HR, 0.40; 95% CI, 0.19-0.87) but not PTEN-intact cancers (HR, 1.18; 95% CI, 0.95-1.48; P heterogeneity = 0.01). Associations did not differ by ERG. Inflammation and immune pathways were enriched in normal prostate tissue of statin ever (n = 10) versus never users (n = 103).

CONCLUSIONS

Molecular tumor classification identified PTEN and inflammation/immune activation as potential mechanisms linking statins with lower lethal prostate cancer risk. These findings support a potential causal association and could inform selection of relevant biomarkers for statin clinical trials.

Tumor protein expression of BRCA1 and development of lethal prostate cancer

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Background: DNA repair genes including BRCA1 are commonly altered in metastatic prostate tumors. However, mutations and copy number aberrations in these genes are rare in primary tumors. Instead, preliminary studies suggest that higher tumor expression of the BRCA1 protein may be associated with worse prognosis. Methods: We undertook a prospective study of tumor BRCA1 protein expression and lethal prostate cancer among men with clinically localized prostate cancer in the Health Professionals Follow-up Study. We performed immunohistochemical staining for BRCA1 on tumor tissue microarrays using a validated antibody and scored expression as positive or negative. We also assessed tumor proliferation by immunostaining for Ki67, angiogenesis by immunostaining for CD34, and apoptosis using a TUNEL assay. Proportional hazards regression was used to evaluate the association between BRCA1 protein expression and development of lethal prostate cancer (metastasis or cancer-specific death). Results: Ten percent of tumors (60 of 589) stained positive for the BRCA1 protein. BRCA1-positive tumors were characterized by higher Gleason scores, a higher proliferative index, and a higher apoptotic index. During a median follow-up of 14.3 years, 18 men (34%) in the BRCA1-positive group and 74 men (14%) in the BRCA1-negative group developed lethal prostate cancer. There was a strong positive association between BRCA1 protein expression and lethal prostate cancer in both unadjusted analyses (HR 2.71, 95% CI 1.73–4.26) and after adjusting for clinical factors (HR 2.00, 95% CI 1.26–3.18). The positive association with BRCA1 protein expression was also independent of proliferation index. Conclusions: Primary prostate tumors expressing the BRCA1 protein have a highly proliferative phenotype and are more likely to progress to lethal disease, independent of its higher proliferative index. Assessing tumor protein expression of BRCA1 may help elucidate the Janus-faced role of DNA repair pathways in prostate cancer progression.[Table: see text]

Effects of Tobacco Smoking on the Tumor Immune Microenvironment in Head and Neck Squamous Cell Carcinoma

PURPOSE

Patients with head and neck squamous cell carcinoma (HNSCC) who actively smoke during treatment have worse survival compared with never-smokers and former-smokers. We hypothesize the poor prognosis in tobacco smokers with HNSCC is, at least in part, due to ongoing suppression of immune response. We characterized the tumor immune microenvironment (TIM) of HNSCC in a retrospective cohort of 177 current, former, and never smokers.

EXPERIMENTAL DESIGN

Tumor specimens were subjected to analysis of CD3, CD8, FOXP3, PD-1, PD-L1, and pancytokeratin by multiplex immunofluorescence, whole-exome sequencing, and RNA sequencing. Immune markers were measured in tumor core, tumor margin, and stroma.

RESULTS

Our data indicate that current smokers have significantly lower numbers of CD8⁺ cytotoxic T cells and PD-L1⁺ cells in the TIM compared with never- and former-smokers. While tumor mutation burden and mutant allele tumor heterogeneity score do not associate with smoking status, gene-set enrichment analyses reveal significant suppression of IFNα and IFNγ response pathways in current smokers. Gene expression of canonical IFN response chemokines, CXCL9, CXCL10, and CXCL11, are lower in current smokers than in former smokers, suggesting a mechanism for the decreased immune cell migration to tumor sites.

CONCLUSIONS

These results suggest active tobacco use in HNSCC has an immunosuppressive effect through inhibition of tumor infiltration of cytotoxic T cells, likely as a result of suppression of IFN response pathways. Our study highlights the importance of understanding the interaction between smoking and TIM in light of emerging immune modulators for cancer management.

Commercial Gene Expression Tests for Prostate Cancer Prognosis Provide Paradoxical Estimates of Race-Specific Risk

BACKGROUND

Commercial gene expression signatures of prostate cancer prognosis were developed and validated in cohorts of predominantly European American men (EAM). Limited research exists on the value of such signatures in African American men (AAM), who have poor prostate cancer outcomes. We explored differences in gene expression between EAM and AAM for three commercially available panels recommended by the National Comprehensive Cancer Network for prostate cancer prognosis.

METHODS

A total of 232 EAM and 95 AAM patients provided radical prostatectomy specimens. Gene expression was quantified using NanoString for 60 genes spanning the Oncotype DX Prostate, Prolaris, and Decipher panels. A continuous expression-based risk score was approximated for each. Differential expression, intrapanel coexpression, and risk by race were assessed.

RESULTS

Clinical and pathologic features were similar between AAM and EAM. Differential expression by race was observed for 48% of genes measured, although the magnitudes of expression differences were small. Coexpression patterns were more strongly preserved by race group for Oncotype DX and Decipher than Prolaris. Poorer prognosis was estimated in EAM versus AAM for Oncotype DX (P < 0.001), whereas negligible prognostic differences were predicted between AAM and EAM using Prolaris or Decipher (P > 0.05).

CONCLUSIONS

Because of observed racial differences across three commercial gene expression panels for prostate cancer prognosis, caution is warranted when applying these panels in clinical decision-making in AAM.

IMPACT

Differences in gene expression by race for three commercial panels for prostate cancer prognosis indicate that further study of their effectiveness in AAM with long-term follow-up is warranted.

epiTAD: a web application for visualizing chromosome conformation capture data in the context of genetic epidemiology

SUMMARY

Complementary advances in genomic technology and public data resources have created opportunities for researchers to conduct multifaceted examination of the genome on a large scale. To meet the need for integrative genome wide exploration, we present epiTAD. This web-based tool enables researchers to compare genomic 3D organization and annotations across multiple databases in an interactive manner to facilitate in silico discovery.

AVAILABILITY AND IMPLEMENTATION

epiTAD can be accessed at https://apps.gerkelab.com/epiTAD/ where we have additionally made publicly available the source code and a Docker containerized version of the application.

Association of statin use with risk of Gleason score-specific prostate cancer: A hospital-based cohort study

BACKGROUND

Conflicting evidence suggests that statins act chemopreventively against prostate cancer (PCa). Whether the association of statin use with PCa risk is Gleason score-dependent, time-, dose-respondent is not well studied.

METHODS

We conducted a cohort study at a tertiary hospital in the Southeastern US using longitudinal data of electronic medical records (EMR) from 1994 to 2016. Only cancer-free men aged >18 years at baseline with follow-up time of ≥12 months were included. Time-dependent Cox proportional hazards regression was used to estimate adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs).

RESULTS

Among 13 065 men, 2976 were diagnosed with PCa over median follow-up of 6.6 years. Statin use was associated with lower risk of both Gleason low- (score <7: aHR, 0.85; 95% CI, 0.74-0.96) and high-grade PCa (score ≥7: aHR, 0.54; 95% CI, 0.42-0.69). The protective association was observed only when statins had been used for a relatively longer duration (≥11 months) or higher dose (≥121 defined daily doses), and were more pronounced for PCa of higher Gleason score (<7: aHR, 0.85, 95% CI, 0.74-0.96; 7 [3 + 4]: aHR, 0.62, 95% CI, 0.43-0.90; 7 [4 + 3]: aHR, 0.49, 95% CI, 0.29-0.82; 8: aHR, 0.60, 95% CI, 0.37-0.96; 9-10: aHR, 0.24, 95% CI, 0.11-0.54). Lipophilic statins (aHR, 0.83; 95% CI, 0.72-0.95) might be more protective than hydrophilic statins (aHR, 0.91, 95% CI, 0.63-1.33) against PCa.

CONCLUSION

Statin use might be associated with reduced PCa risk only when used for a relatively longer duration, and the risk reduction was higher for PCa of higher Gleason score.

Identification of jointly correlated gene sets

Associations between expressions of genes play a key role in deciphering their functions. Correlation score between pairs of genes is often utilized to associate two genes. However, the relationship between genes is often more complex; multiple genes might collaborate to control the transcription of a gene. In this paper, we introduce the problem of searching pairs of genes, which collectively correlate with another gene. This problem is computationally much harder than the classical problem of identifying pairwise gene associations. Exhaustive search is infeasible for transcriptomic datasets also; since for [Formula: see text] genes, there are [Formula: see text] possible gene combinations. Our method builds three filters to avoid computing the association for a large fraction of the gene combinations, which do not produce high correlation. Our experiments on a synthetic dataset and a prostate cancer dataset demonstrate that our method produces accurate results at the transcriptome level in practical time. Moreover, our method identifies biologically novel results which classical pairwise gene association studies are unlikely to discover.

Methylmercury exposure, genetic variation in metabolic enzymes, and the risk of glioma

Methylmercury (MeHg) is an environmental neurotoxin with human exposure mainly from dietary intake of contaminated fish. Exposure to MeHg has been implicated in neurological damage, but research on its role in cancers, specifically glioma, is limited. In a glioma case-control study, we examined associations between toenail mercury (Hg) and glioma risk. We also examined genetic polymorphisms in 13 genes related to MeHg metabolism for association with glioma risk; genetic associations were also studied in the UK Biobank cohort. Median toenail Hg in cases and controls, respectively, was 0.066 μg/g and 0.069 μg/g (interquartile range (IQR): 0.032-0.161 and 0.031-0.150 μg/g). Toenail Hg was not found to be significantly associated with glioma risk (Odds Ratio: 1.02; 95% Confidence Interval: 0.91, 1.14; p = 0.70 in analysis for ordinal trend with increasing quartile of toenail MeHg). No genetic variant was statistically significant in both of the studies; one variant, rs11859163 (MMP2) had a combined p-value of 0.02 though it was no longer significant after adjustment for multiple testing (Bonferroni corrected p = 1). This study does not support the hypothesis that exposure to MeHg plays a role in the development of glioma at levels of exposure found in this study population.

Abstract 4470: Aneuploidy drives lethal progression in prostate cancer

Purpose: Aneuploidy, defined as chromosome gains and losses, is a hallmark of cancer. However, extensive aneuploidy is relatively rare in prostate cancer. We sought to investigate whether extent of aneuploidy is associated with lethal progression in a large cohort of prostate cancer patients, an untested hypothesis.

Methods: To assess chromosome arm gains and losses in archival tumor specimens, we developed a computational method based on normalized gene expression sums of whole-transcriptome profiling in primary prostate tumors from The Cancer Genome Atlas (TCGA) and validated it against DNA copy numbers. We applied this method to tumor tissue from cancer diagnosis from patients diagnosed during prospective follow-up of two cohort studies, the Health Professionals Follow-up Study (HPFS) and the Physicians’ Health Study (PHS). These tumors underwent centralized histopathologic review including Gleason grading and immunohistochemistry to characterize proliferation (Ki-67), apoptosis (TUNEL), PTEN loss, and MYC amplification. Patients were followed for lethal disease (metastases and prostate cancer-specific death) on median for 15 years.

Results: Extensive aneuploidy (&gt;=5 gained or lost chromosome arms) was present in 23% of the 333 primary prostate cancers from TCGA. Even 68% of low-risk cancers (Gleason grade &lt;=3+4) had &gt;= 1 altered chromosome arm. Our algorithm detected aneuploidy based on transcriptome profiling with high discriminative accuracy (area under the curve [AUC] for any aneuploidy, 0.83; AUC for &gt;=5 chromosome arms, 0.87). Tumors with greater extent of aneuploidy had higher Gleason scores, but little to no increase in proliferative and apoptotic indices. Among the 404 patients from HPFS and PHS, 113 lethal events occurred. Greater extent of aneuploidy was strongly associated with a higher risk of lethal disease. Patients with &gt;=5 predicted altered chromosome arms had 5.3 times higher odds of lethal disease (95% confidence interval, 2.2-13.1) compared to those without aneuploidy after adjusting for Gleason grade. Aneuploidy was strongly associated with lethal disease even among men with high-risk Gleason grade 8-10 tumors. Chromosome arms 8q and 10q were among the commonly altered arms. The elevated risk associated with 10q deletion and 8q gain was not considerably attenuated when accounting for PTEN loss and MYC overexpression on the respective arms.

Conclusions: The extent of aneuploidy can be estimated from transcriptome profiling, which allows assessment of archival, formalin-fixed paraffin-embedded tumors. Given the complex interactions between genes colocalized on a chromosome arm, the loss or gain of an entire chromosome arm confers aggressiveness beyond affecting well-described tumor suppressors or oncogenes on that arm and beyond altering histologic tumor grade. Our results have clinical implications and point to a key role of aneuploidy in driving aggressive disease in primary prostate cancer.

Citation Format: Konrad H. Stopsack, Charles A. Whittaker, Travis A. Gerke, Massimo Loda, Philip W. Kantoff, Lorelei A. Mucci, Angelika Amon. Aneuploidy drives lethal progression in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4470.

Abstract 4471: Commercial gene expression tests for prostate cancer prognosis provide paradoxical estimates of race-specific risk

Background: Current National Comprehensive Cancer Network (NCCN) guidelines recommend three gene expression-based tests for prostate cancer (PCa) prognosis in men with low or favorable intermediate risk disease: Decipher, Oncotype DX Prostate, and Prolaris. The three tests feature varying numbers of genes with minimal overlap. Importantly, development and validation efforts for all three panels were undertaken in predominantly European American men (EAM) cohorts, and limited research exists on the value of such signatures in African American men (AAM), who have poorer PCa outcomes. Here, we explored differences in gene expression between EAM and AAM for the three panels recommended by the NCCN for PCa prognosis.

Methods: 232 EAM and 95 AAM patients provided radical prostatectomy specimens. Gene expression was quantified using Nanostring for 60 genes spanning the Oncotype DX Prostate, Prolaris, and Decipher panels. Differential expression and intrapanel co-expression by race were assessed using Mann-Whitney tests and Spearman’s correlations, respectively. A continuous expression-based risk score was approximated for each panel with higher scores indicating worse outcomes. Race-specific risks were compared using Mann-Whitney tests and Spearman’s correlations.

Results: Clinical and pathologic features were similar between AAM and EAM. Differential expression by race was observed for 48% of genes measured, though the magnitudes of expression differences were small. Co-expression patterns were more strongly preserved by race group for Oncotype DX and Decipher versus Prolaris (integrative correlations of 0.87, 0.73, and 0.62, respectively). Paradoxically, poorer prognosis was estimated in EAM versus AAM for Prolaris and Oncotype DX (p = 0.01 for both), whereas worse prognosis was predicted for AAM versus EAM using Decipher (p &lt; 0.001).

Discussion: Due to observed racial differences across three commercial gene expression panels for PCa prognosis, caution is warranted when applying these panels in clinical decision-making in AAM. Replication of our findings directly on the commercial panels with long-term follow-up is warranted.

Citation Format: Jordan H. Creed, Anders E. Berglund, Robert J. Rounbehler, Shivanshu Awasthi, John L. Cleveland, Jong Y. Park, Kosj Yamoah, Travis A. Gerke. Commercial gene expression tests for prostate cancer prognosis provide paradoxical estimates of race-specific risk [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4471.

A Novel Mechanism Driving Poor-Prognosis Prostate Cancer: Overexpression of the DNA Repair Gene, Ribonucleotide Reductase Small Subunit M2 (RRM2)

PURPOSE

Defects in genes in the DNA repair pathways significantly contribute to prostate cancer progression. We hypothesize that overexpression of DNA repair genes may also drive poorer outcomes in prostate cancer. The ribonucleotide reductase small subunit M2 (RRM2) is essential for DNA synthesis and DNA repair by producing dNTPs. It is frequently overexpressed in cancers, but very little is known about its function in prostate cancer.

EXPERIMENTAL DESIGN

The oncogenic activity of RRM2 in prostate cancer cells was assessed by inhibiting or overexpressing RRM2. The molecular mechanisms of RRM2 function were determined. The clinical significance of RRM2 overexpression was evaluated in 11 prostate cancer clinical cohorts. The efficacy of an RRM2 inhibitor (COH29) was assessed in vitro and in vivo. Finally, the mechanism underlying the transcriptional activation of RRM2 in prostate cancer tissue and cells was determined.

RESULTS

Knockdown of RRM2 inhibited its oncogenic function, whereas overexpression of RRM2 promoted epithelial mesenchymal transition in prostate cancer cells. The prognostic value of RRM2 RNA levels in prostate cancer was confirmed in 11 clinical cohorts. Integrating the transcriptomic and phosphoproteomic changes induced by RRM2 unraveled multiple oncogenic pathways downstream of RRM2. Targeting RRM2 with COH29 showed excellent efficacy. Thirteen putative RRM2-targeting transcription factors were bioinformatically identified, and FOXM1 was validated to transcriptionally activate RRM2 in prostate cancer.

CONCLUSIONS

We propose that increased expression of RRM2 is a mechanism driving poor patient outcomes in prostate cancer and that its inhibition may be of significant therapeutic value.

Pre-orchiectomy tumor marker levels should not be used for International Germ Cell Consensus Classification (IGCCCG) risk group assignment

PURPOSE

To investigate whether the use of pre-orchiectomy instead of pre-chemotherapy tumor marker (TM) levels has an impact on the International Germ Cell Consensus Classification (IGCCCG) risk group assignment in patients with metastatic germ cell tumors (GCT).

METHODS

Demographic and clinical information of all patients treated for primary metastatic testicular non-seminomatous GCT in our tertiary care academic center were extracted from medical charts. IGCCCG risk group assignment was correctly performed with pre-chemotherapy marker levels and additionally with pre-orchiectomy marker levels. Agreement between pre-chemotherapy and pre-orchiectomy risk group assignments was assessed using Cohen's kappa.

RESULTS

Our cohort consisted of 83 patients. The use of pre-orchiectomy TMs resulted in an IGCCCG risk group upstaging in 12 patients (16%, 8 patients from good to intermediate risk and 4 patients from intermediate to poor risk) and a downstaging in 1 patient (1.2%, from intermediate- to good-risk). The agreement between pre-orchiectomy and pre-chemotherapy IGCCCG risk groups resulted in a Cohen's kappa of 0.888 (p < 0.001).

CONCLUSIONS

Using pre-orchiectomy TMs can result in incorrect IGCCCG risk group assignment, which in turn can impact on the clinical management and follow-up of patients with metastatic GCT. Thus, adherence to the IGCCCG standard using pre-chemotherapy TMs levels is recommended.

BMI trajectories and risk of overall and grade-specific prostate cancer: An observational cohort study among men seen for prostatic conditions

Background

Dynamic longitudinal patterns in body mass index (BMI) have been suggested to better predict health outcomes than static measures. Effects of BMI trajectories on prostate cancer (PCa) risk have not been thoroughly explored.

Methods

Cohort data were derived from electronic medical records of patients who were admitted to a tertiary‐care hospital in the Southeastern USA during 1994‐2016. Patients with a history of urologic clinic visit because of any prostatic condition and with repeatedly measured BMI (n = 4857) were included. BMI trajectories prior to PCa diagnosis were assessed using the developmental trajectory analysis method. Cox proportional hazards regression modeling was used to estimate adjusted hazard ratio (aHR) with 95% confidence intervals (CIs) for overall and grade‐specific PCa.

Results

The median age (interquartile range, IQR) of the participants at baseline was 63 (54, 72) years. Over a median follow‐up (IQR) of 8.0 (2.0, 13.0) years, 714 (14.7%, 714/4857) were diagnosed with PCa. Men with growing BMI trajectory progressing from normal weight to overweight/obese had a 76% increased PCa risk (aHR = 1.76; 95% CI: 1.25, 2.48), and men being obese and experiencing progressive weight gain had 3.72‐fold increased PCa risk (aHR = 3.72; 95% CI: 1.60, 8.66), compared to men with persistently normal BMI. The associations were more pronounced for PCa with Gleason score ≥7. No significant association of decreasing BMI trajectory progressing from obese to normal BMI was found with PCa risk.

Conclusions

Progressively body weight gain during middle‐to‐late adulthood was associated with increased PCa risk for both normal weight and overweight men. Further studies are warranted to confirm this finding.

Abstract A015: Molecular tumor profiling to identify mechanisms linking statin use with lower risk of lethal prostate cancer: Results from the Health Professionals Follow-up Study

Introduction: Epidemiologic data support an inverse association between statin use and risk of lethal prostate cancer, but contributing mechanisms have not been elucidated. Herein, using data from the Health Professionals Follow-up Study (HPFS), we updated our previous analysis of statins and lethal prostate cancer with a decade of additional follow-up, and incorporated immunohistochemistry (IHC)-based biomarkers and gene expression profiling to identify putative molecular mechanisms contributing to the association.

Methods: We included data from 44,076 HPFS participants who were cancer free in 1990, with follow-up through 2012. Participants reported prediagnostic statin use on biennial questionnaires. Statin use was categorized as current vs. never/past use, with current users further categorized as long-term vs. short-term users (≥6 vs. &lt;6 years). To classify prostate cancer molecular subtypes, genetically validated IHC assays for TMPRSS2:ERG fusion and PTEN loss were conducted on tissue microarrays for 891 and 660 cases, respectively. Whole-genome mRNA profiling of tumor and adjacent normal tissue was completed for 237 and 114 cases, respectively, using Affymetrix GeneChip Human Gene 1.0 ST arrays. We used Cox proportional hazards analysis to generate hazard ratios (HR) and 95% confidence intervals (CI) for associations between statin use and risk of overall, advanced (stage T3b or higher at diagnosis, metastatic or fatal), and lethal (metastatic or fatal) prostate cancer, as well as molecular subtypes, adjusted for PSA testing behavior and potential confounders including obesity and smoking. Moreover, we explored gene expression pathways in tumor and adjacent normal prostate tissue of statin users vs. nonusers using gene set enrichment analysis (GSEA).

Results: During 22 years of follow-up, 6,144 men were diagnosed with prostate cancer; 1,051 (17%) had advanced disease and 827 (13%) developed lethal prostate cancer. Of cases with molecular subtype available, 48% were ERG-positive and 14% PTEN-null. In multivariable analysis, relative to never/past use, current statin use was inversely associated with risk of advanced (HR 0.84; 95% CI 0.68-1.04) and lethal (HR 0.78; 95% CI 0.68-1.01) prostate cancer. These associations were more pronounced in long-term users, where ≥6 years of prediagnosis statin use was significantly associated with a lower risk of advanced (HR 0.72; 95% CI 0.53-0.97) and lethal prostate cancer (HR 0.64; 95% CI 0.45-0.92), relative to nonuse. Long-term statin use was not associated with overall prostate cancer risk, whether ERG-positive (HR 0.89; 95% CI 0.59-1.35) or ERG-negative (HR 1.06; 95% CI 0.74-1.50). However, relative to nonuse, a longer duration of prediagnosis statin use was associated with reduced risk of PTEN-null cancers (HR 0.42; 95% CI 0.20-0.90), but not PTEN-intact disease (HR 1.18; 95% CI 0.95-1.46; p-heterogeneity=0.01). In GSEA, we identified T cell, B cell, and phosphatidylinositol (PI3K) signaling among the top pathways enriched in tumor-adjacent normal prostate tissue of current statin users, relative to never users. Intriguingly, no gene sets were differentially expressed by statin use in the tumor.

Discussion: Our updated findings from the HPFS are consistent with our prior findings and other epidemiologic data supporting a role for statins in lethal prostate cancer prevention. Molecular classification of tumors identified PTEN/PI3K signaling and inflammation/immune activation as two potential mechanisms contributing to this association. Elucidating molecular mechanisms mediating the association between statin use and lower risk of lethal prostate cancer will provide support for a causal effect of statins on lethal prostate cancer risk and could inform statin clinical trials with appropriate intermediate endpoints.

Citation Format: Emma H. Allott, Ericka M. Ebot, Amparo G. Gonzalez-Feliciano, Sarah C. Markt, Kathryn M. Wilson, Thomas U. Ahearn, Travis A. Gerke, Mary K. Downer, Konrad H. Stopsack, Jennifer R. Rider, Stephen J. Freedland, Elizabeth A. Platz, Meir J. Stampfer, Edward L. Giovannucci, Christopher J. Sweeney, Stephen P. Finn, Lorelei A. Mucci. Molecular tumor profiling to identify mechanisms linking statin use with lower risk of lethal prostate cancer: Results from the Health Professionals Follow-up Study [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A015.

Abstract LB-275: Targeting poor-prognosis subtypes of prostate cancer by inhibition of DNA repair gene ribonucleotide reductase small subunit M2

Studies reveal defective DNA repair contribute to prostate cancer (PC) progression. We hypothesize that overexpression of DNA repair genes could also contribute to poorer outcomes in PC. The nucleotide metabolism enzyme ribonucleotide reductase (RNR) is essential for DNA synthesis and DNA repair by producing dNTPs. The small subunit M2 (RRM2), as the rate-limiting RNR subunit, is frequently up-regulated in cancers. Clinically, targeting of RRM2 with small molecules is being tested in multiple cancers, but there is little knowledge of RRM2 function in PC. The analysis of multiple PC clinical cohorts (total include 1602 cases) revealed that high RRM2 level was associated with poor clinical outcomes, including a higher likelihood of metastasis (p&lt;0.001), biochemical recurrence (p&lt;0.001), and lethality (p&lt;0.0001). In PC cells, knockdown of RRM2 inhibited dNTP production and induced DNA damage, which led to significant cell growth inhibition, major S phase arrest, and apoptosis. Overexpression of RRM2 promoted epithelial-mesenchymal transition (EMT) by increasing the expression of multiple EMT markers. Furthermore, the small molecule RRM2 inhibitor (COH29) induced a similar phenotype as knocking down RRM2 in PC cells. RNA-Seq analysis in siRRM2 or COH29 treated PC cells provided a global assessment of RRM2-regulated transcriptome changes. GSEA analysis revealed that inhibition of RRM2 could activate biological processes including cell cycle checkpoint, DNA damage response, and apoptotic signaling. COH29 treatment could target genes highly enriched in PC. We further applied an RRM2-regulated gene signature (from RNA-Seq datasets) to TCGA and Taylor cohorts. Intriguingly, the RRM2 signature was highly correlated with metastasis and disease free survival (p&lt;0.001). Furthermore, inhibition of RRM2 specifically targets poor prognostic luminal subtypes (PCS1 subtype; Lum B in PAM50 classifier) recently reported. Besides transcriptome changes, protein kinase arrays showed that AKT/mTOR and SFK-STAT signaling were repressed by inhibition of RRM2. These oncogenic signaling pathways are crucial for EMT program. Amplification of RRM2 is rare in PC and transcriptional activation of RRM2 may play a major role in overexpression of RRM2. H3K27ac ChIP-Seq from tissues revealed more activated RRM2 promoter in PC than in normal prostate. 13 potential RRM2-targeting transcription factors (TFs) were identified by integrating clinical cohorts and a TF database. They showed a positive correlation with RRM2 expression in PC cohorts. Among these TFs, FOXM1 was reported to be the master driver of the aggressive luminal subtype of PC. We revealed that FOXM1 expression was associated with clinical outcomes. The ChIP-PCR and luciferase reporter assays provided evidence of physical binding of FOXM1 to the RRM2 promoter in PC cells. Knockdown of FOXM1 significantly repressed RRM2 mRNA and protein levels. Altogether, FOXM1-regulated transcriptional activation contributes to overexpression of RRM2. Intriguingly, COH29 can also repress FOXM1 expression, which leads to transcription repression of RRM2. Altogether, our study elucidated the molecular mechanisms underlying RRM2 oncogenic functions and the transcriptional regulation of RRM2 in PC cells. We suggest that RRM2 can be a novel therapeutic target for PC treatment.

Citation Format: Ying Z. Mazzu, Joshua Armenia, Goutam Chakraborty, Yuki Yoshikawa, Travis A. Gerke, Si Ana A. Coggins, Xintao Qiu, Mohammad Atiq, Konrad H. Stopsack, Gwo-Shu Mary Lee, Henry W. Long, Baek Kim, Matthew L. Freedman, Mark M. Pomerantz, Lorelei A. Mucci, Philip W. Kantoff. Targeting poor-prognosis subtypes of prostate cancer by inhibition of DNA repair gene ribonucleotide reductase small subunit M2 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-275.

Abstract 1450: Intratumoral CYP27A1 expression in relation to cholesterol synthesis and vitamin D signaling and its association with lethal prostate cancer

Background: Higher intratumoral cholesterol synthesis is associated with a worse prognosis in prostate cancer. A recent study identified the vitamin D-regulated enzyme CYP27A1, which converts cholesterol to 27-hydroxycholesterol, to negatively affect cholesterol synthesis and to be associated with biochemical recurrence. We hypothesized that low CYP27A1 expression occurs in patients with low vitamin D signaling and high intratumoral cholesterol synthesis, and that low CYP27A1 expression is associated with higher risk of lethal prostate cancer.

Methods: We studied 404 prostate cancer patients in the prospective Health Professionals Follow-up Study (HPFS) and the Physicians' Health Study (PHS) cohorts. After centralized histopathologic review, we measured tumor expression of CYP27A1, SQLE (as a measure of cholesterol synthesis), and CYP24A1 (as a proxy of vitamin D signaling) using mRNA expression profiling. In subgroups, prediagnostic plasma levels of 25-hydroxyvitamin D (25(OH)D, n = 132) and tumor protein expression of the vitamin D receptor (VDR, n = 300) were also available. Using logistic regression, we estimated odds ratios (ORs) for lethal prostate cancer, defined as prostate cancer mortality or metastases, in contrast to non-lethal disease without metastases after at least eight years of follow up.

Results: CYP27A1 expression was weakly positively correlated with expression of the vitamin D target gene CYP24A1 (r = 0.17; p &lt; 0.001) but did not differ by plasma 25(OH)D (p-trend = 0.59) or by VDR expression (p-trend = 0.26). CYP27A1 expression was lower in tumors with higher expression of the second rate-limiting enzyme of cholesterol synthesis, SQLE (r = -0.21; p &lt; 0.001). Tumors with higher Gleason grade had lower CYP27A1 expression (HPFS, p &lt; 0.001; PHS, p = 0.004). Higher CYP27A1 was associated with lower risk of lethal cancer in HPFS (OR for highest vs. lowest quintile of expression, 0.31; 95% CI, 0.13 to 0.73; p-trend = 0.007) and in PHS (OR, 0.10; 95% CI, 0.01 to 0.88; p-trend = 0.043) in univariable models. Combining the cohorts and adjusting for baseline clinical characteristics and SQLE, the OR was 0.30 (95% CI, 0.12 to 0.72; p-trend = 0.009). CYP27A1 was less strongly associated with lethal disease when additionally adjusting for Gleason grade (OR, 0.48; 95% CI, 0.18 to 1.31; p-trend = 0.21).

Conclusion: Low CYP27A1 expression is associated with higher cholesterol synthesis and a higher risk of progression to lethal disease among prostate cancer patients, potentially partly due to its association with higher Gleason grade. We found little evidence that intratumoral CYP27A1 expression is associated with circulating 25(OH)D. Our results highlight the importance of the regulation of cholesterol metabolism in prostate cancer progression.

Citation Format: Nabeela A. Khan, Konrad H. Stopsack, Emma H. Allott, Travis A. Gerke, Edward L. Giovannucci, Lorelei A. Mucci, Philip W. Kantoff. Intratumoral CYP27A1 expression in relation to cholesterol synthesis and vitamin D signaling and its association with lethal prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1450.

Regular aspirin use and gene expression profiles in prostate cancer patients

PURPOSE

Pharmacoepidemiology studies suggest prognostic benefits of aspirin in prostate cancer. We hypothesized that aspirin induces transcriptional changes in tumors or normal prostate tissue.

METHODS

We analyzed the prostatic transcriptome from men diagnosed with prostate cancer during follow-up of the Physicians' Health Study 1 (PHS, n = 149), initially a randomized controlled trial of aspirin. Aspirin target genes were identified through systematic literature review and a drug target database. We compared target gene expression according to regular aspirin use at cancer diagnosis and used whole-transcriptome gene set enrichment analysis to identify gene sets associated with aspirin use. Results were validated in the Health Professionals Follow-up Study (HPFS, n = 254) and in Connectivity Map.

RESULTS

Of 12 target genes identified from prior studies and 540 genes from the drug target database, none were associated with aspirin use. Twenty-one gene sets were enriched in tumor tissue of aspirin users, 18 of which were clustered around ribosome function and translation. These gene sets were associated with exposure to cyclooxygenase inhibitors in Connectivity Map. Their association with cancer prognosis was U-shaped in both cohorts. No gene sets were enriched in normal tissue. In HPFS, neither the target genes nor the gene sets were associated with aspirin use.

CONCLUSIONS

Regular aspirin use may affect ribosome function in prostate tumors. Other putative target genes had similar expression in tumors from aspirin users and non-users. If results are corroborated by experimental studies, a potential benefit of aspirin may be limited to a subset of prostate cancer patients.

ATR inhibition controls aggressive prostate tumors deficient in Y-linked histone demethylase KDM5D

Epigenetic modifications control cancer development and clonal evolution in various cancer types. Here, we show that loss of the male-specific histone demethylase lysine-specific demethylase 5D (KDM5D) encoded on the Y chromosome epigenetically modifies histone methylation marks and alters gene expression, resulting in aggressive prostate cancer. Fluorescent in situ hybridization demonstrated that segmental or total deletion of the Y chromosome in prostate cancer cells is one of the causes of decreased KDM5D mRNA expression. The result of ChIP-sequencing analysis revealed that KDM5D preferably binds to promoter regions with coenrichment of the motifs of crucial transcription factors that regulate the cell cycle. Loss of KDM5D expression with dysregulated H3K4me3 transcriptional marks was associated with acceleration of the cell cycle and mitotic entry, leading to increased DNA-replication stress. Analysis of multiple clinical data sets reproducibly showed that loss of expression of KDM5D confers a poorer prognosis. Notably, we also found stress-induced DNA damage on the serine/threonine protein kinase ATR with loss of KDM5D. In KDM5D-deficient cells, blocking ATR activity with an ATR inhibitor enhanced DNA damage, which led to subsequent apoptosis. These data start to elucidate the biological characteristics resulting from loss of KDM5D and also provide clues for a potential novel therapeutic approach for this subset of aggressive prostate cancer.

Toenail selenium, genetic variation in selenoenzymes and risk and outcome in glioma

BACKGROUND

Selenium is an essential trace element obtained through diet that plays a critical role in DNA synthesis and protection from oxidative damage. Selenium intake and polymorphisms in selenoproteins have been linked to the risk of certain cancers though data for glioma are sparse.

METHODS

In a case-control study of glioma, we examined the associations of selenium in toenails and genetic variants in the selenoenzyme pathway with the risk of glioma and patient survival. A total of 423 genetic variants in 29 candidate genes in the selenoenzyme pathway were studied in 1547 glioma cases and 1014 healthy controls. Genetic associations were also examined in the UK Biobank cohort comprised of 313,868 persons with 322 incident glioma cases. Toenail selenium was measured in a subcohort of 300 glioma cases and 300 age-matched controls from the case-control study.

RESULTS

None of the 423 variants studied were consistently associated with glioma risk in the case-control and cohort studies. Moreover, toenail selenium in the case-control study had no significant association with glioma risk (p trend = 0.70) or patient survival among 254 patients with high grade tumors (p trend = 0.70).

CONCLUSION

The present study offers no support for the hypothesis that selenium plays a role in the onset of glioma or patient outcome.

Regulation of the tumor suppressor PLZF and prostate cancer prognosis

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Background: PLZF ( ZBTB16) is an androgen-regulated tumor suppressor gene. Homozygous PLZF deletions are seen in a proportion of localized as well as castration-resistant prostate cancers (PC). Since PTEN has been shown to regulate PLZF expression in vitro, we hypothesized that PTEN status impacts PLZF expression in men with PC. We further hypothesized that low PLZF is associated with a poorer PC prognosis. Methods: We studied patients diagnosed with PC during prospective follow-up of the Health Professionals Follow-up Study (HPFS; n = 254) and the Physicians’ Health Study (PHS; n = 150). We performed whole transcriptome profiling of tumor specimens from cancer diagnosis and, in a subset of patients ( n = 253), a genomically-validated immunohistochemistry for PTEN. Patients were followed for metastases and PC-specific mortality (lethal cancer) after primary treatment for a median of 14 years. Univariable linear and multivariable logistic regression models for cancer outcomes, adjusted for age and calendar year, were used. For validation, the association of PTEN copy number variations and PLZF mRNA expression was assessed in The Cancer Genome Atlas (TCGA) primary PC cohort (n = 333). Results: Loss of PTEN protein expression was associated with lower PLZF expression (–0.72 standard deviations [SD]; 95% CI, –0.38 to –1.06; p < 0.001; HPFS and PHS cohorts), as were copy number variations in PTEN (TCGA cohort; –0.46 SD for deep deletions vs. diploid status; 95% CI, –0.13 to –0.79; p = 0.006) . PLZF expression did not differ significantly by Gleason grade in any cohort (all p > 0.09). In both the HPFS and PHS cohorts, the 25% of patients with the lowest PLZF expression were significantly more likely than those with higher expression to have progression to lethal cancer. This association was independent from Gleason grade, PTEN loss, and a signature of androgen receptor signaling (adjusted odds ratio for lethal cancer, 2.69; 95% CI, 1.18 to 6.14; p = 0.019). Conclusions: Loss of PTEN expression is associated with lower expression of PLZF amongst primary PC not exposed to ADT. In line with its action as a tumor suppressor, low PLZF expression is associated with lethal PC. Whether further suppression of PLZF with ADT worsens outcomes in advanced PC needs further study.

Prognostic and therapeutic significance of ribonucleotide reductase small subunit M2 in prostate cancer

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Background: DNA-repair defects are common in advanced prostate cancer (PC) and high-risk localized tumors. Besides deficiency of DNA repair, overexpression of DNA repair genes could also contribute to poorer outcomes for PC patients. The nucleotide metabolism enzyme ribonucleotide reductase (RNR) plays the key role in DNA synthesis and repair. RRM2, the rate-limiting RNR subunit, is frequently up-regulated in cancer, and its overexpression leads to chemoresistance. Although targeting RRM2 by siRNA and small molecules has been applied in clinical trials in multiple cancers, limited knowledge of RRM2 function in PC delays potential clinical application of RRM2 inhibition. Methods: We leveraged publically available PC clinical cohorts to examine RRM2 levels and clinical outcomes. siRNAs was applied to knockdown of RRM2 in multiple PC cell lines. Cell growth, cell cycle and apoptosis were analyzed to determine siRRM2 or RRM2 inhibitor (COH29)-induced phenotypes. RNA-seq and protein array were performed to identify downstream targets of RRM2. Immunohistochemistry staining was applied to determine prevalence of RRM2 protein expression in PC tissues microarrays (TMAs). Results: In PC cohorts, increased RRM2 expression was associated with a higher likelihood of metastasis, poorer disease-free survival, and increased risk of development of lethal disease (N = 1200, PHS/HPFS cohorts). In PC cells, Inhibition of RRM2 induced remarkable cell growth inhibition, cell cycle arrest (at S phase) and apoptosis. DNA damage was observed in siRRM2/COH29-treated PC cells with increased activation of DNA damage markers. GSEA analysis of the RNA-seq dataset revealed multiple biological processes were affected by inhibition of RRM2, such as cell cycle, apoptosis, and DNA damage response. Intriguingly, MYC oncogenic signaling is the major downstream targets of RRM2. Furthermore, inhibition of RRM2 can block multiple oncogenic signaling including mTOR/AKT, SFK, and STAT signaling by repressing the key phospho-kinases in PC cells. Among 121 cases on the PC TMAs, 20% showed strong RRM2 protein expression. Conclusions: RRM2 may serve as a prognostic biomarker and novel therapeutic target in PC.

Association between age-related reductions in testosterone and risk of prostate cancer-An analysis of patients' data with prostatic diseases

The relationship between serum total testosterone and prostate cancer (PCa) risk is controversial. The hypothesis that faster age-related reduction in testosterone is linked with increased PCa risk remains untested. We conducted our study at a tertiary-level hospital in southeast of the USA, and derived data from the Medical Registry Database of individuals that were diagnosed of any prostate-related disease from 2001 to 2015. Cases were those diagnosed of PCa and had one or more measurements of testosterone prior to PCa diagnosis. Controls were those without PCa and had one or more testosterone measurements. Multivariable logistic regression models for PCa risk of absolute levels (one-time measure and 5-year average) and annual change in testosterone were respectively constructed. Among a total of 1,559 patients, 217 were PCa cases, and neither one-time measure nor 5-year average of testosterone was found to be significantly associated with PCa risk. Among the 379 patients with two or more testosterone measurements, 27 were PCa cases. For every 10 ng/dL increment in annual reduction of testosterone, the risk of PCa would increase by 14% [adjusted odds ratio, 1.14; 95% confidence interval (CI), 1.03-1.25]. Compared to patients with a relatively stable testosterone, patients with an annual testosterone reduction of more than 30 ng/dL had 5.03 [95% CI: 1.53, 16.55] fold increase in PCa risk. This implies a faster age-related reduction in, but not absolute level of serum total testosterone as a risk factor for PCa. Further longitudinal studies are needed to confirm this finding.

Cholesterol uptake and regulation in high-grade and lethal prostate cancers

Lethal prostate cancers have higher expression of squalene monooxygenase (SQLE), the second rate-limiting enzyme of cholesterol synthesis. Preclinical studies suggested that aberrant cholesterol regulators, receptors and transporters contribute to cholesterol accumulation uniformly. We assessed their association with features of aggressive cancers. In the prospective prostate cancer cohorts within the Health Professional Follow-up Study, the Physicians' Health Study and the Swedish Watchful Waiting Study, tumor mRNA expression profiling was performed. Lethal disease was defined as mortality or metastases from prostate cancer (n = 266) in contrast to non-lethal disease without metastases after >8 years of follow-up (n = 476). Associations with Gleason grade were additionally assessed using The Cancer Genome Atlas primary prostate cancer dataset (n = 333). Higher Gleason grade was associated with lower LDLR expression, lower SOAT1 and higher SQLE expression. Besides high SQLE expression, cancers that became lethal despite primary treatment were characterized by low LDLR expression (odds ratio for highest versus lowest quintile, 0.37; 95% CI 0.18-0.76) and by low SOAT1 expression (odds ratio, 0.41; 95% CI 0.21-0.83). The association of LDLR expression and lethality was not present in tumors with high IDOL expression. ABCA1, PCSK9 or SCARB1 expressions were not associated with Gleason grade or lethal cancer. In summary, prostate cancers that progress to lethal disease rely on de novo cholesterol synthesis (via SQLE), rather than transcellular uptake (via LDLR) or cholesterol esterification (via SOAT1). These results may help design pharmacotherapy for high-risk patients.

Abstract PR09: Prostate cancer prognostication based on an actionable metabolic pathway

Background: We recently discovered that mRNA expression of SQLE, coding for squalene monooxygenase, the second rate-limiting enzyme of cholesterol synthesis, is associated with lethality after prostate cancer diagnosis. Here, we investigate how expression of SQLE and other key regulators of cholesterol homeostasis, identified by prior mechanistic studies, aid risk prediction for lethal prostate cancer.

Methods: The Health Professionals Follow-up Study and the Physicians' Health Study prostate cancer tissue cohorts collected tissue from prostatectomy or transurethral resection of the prostate at cancer diagnosis. Whole-transcriptome profiling was performed. The outcome of interest was lethal cancer defined as prostate cancer mortality or development of metastases in contrast to non-lethal cancer without evidence of metastases after at least eight years of follow up. Discrimination for prostate lethal cancer was assessed by comparing c-statistics using bootstrap resampling.

Results: Combining both cohorts, 112 men had lethal prostate cancer; 290 men had non-lethal cancer. A prognostic model for lethal cancer including Gleason grade, pathologic stage, age, and year of diagnosis had a high c = 0.885; adding body mass index, smoking status, family history of prostate cancer, and diabetes diagnosis increased c to 0.889. A model containing only SQLE (linear) achieved c = 0.663. Adding SQLE to the fully adjusted model increased c to 0.903 (p = 0.027). None of the other cholesterol regulators ABCA1, ACAT1, LDLR, and SCARB1 improved discrimination.

Conclusions: SQLE performs well as a single biomarker of prostate cancer lethality after primary therapy, in contrast to other markers of intratumoral cholesterol regulation. Improvements in prognostication are minimal when SQLE is added to a model that contains a centrally re-reviewed Gleason grade. Most importantly, SQLE may be an actionable, predictive biomarker of benefit from statin therapy, which addresses the cholesterol synthesis pathway regulated by SQLE.

Citation Format: Konrad H. Stopsack, Travis A. Gerke, Lorelei A. Mucci, Jennifer R. Rider. Prostate cancer prognostication based on an actionable metabolic pathway. [abstract]. In: Proceedings of the AACR Special Conference: Improving Cancer Risk Prediction for Prevention and Early Detection; Nov 16-19, 2016; Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(5 Suppl):Abstract nr PR09.

Perineural Invasion and Risk of Lethal Prostate Cancer

Background: Prostate cancer has a propensity to invade and grow along nerves, a phenomenon called perineural invasion (PNI). Recent studies suggest that the presence of PNI in prostate cancer has been associated with cancer aggressiveness.Methods: We investigated the association between PNI and lethal prostate cancer in untreated and treated prostate cancer cohorts: the Swedish Watchful Waiting Cohort of 615 men who underwent watchful waiting, and the U.S. Health Professionals Follow-Up Study of 849 men treated with radical prostatectomy. One pathologist performed a standardized histopathologic review assessing PNI and Gleason grade. Patients were followed from diagnosis until metastasis or death.Results: The prevalence of PNI was 7% and 44% in the untreated and treated cohorts, respectively. PNI was more common in high Gleason grade tumors in both cohorts. PNI was associated with enhanced tumor angiogenesis, but not tumor proliferation or apoptosis. In the Swedish study, PNI was associated with lethal prostate cancer [OR 7.4; 95% confidence interval (CI), 3.6-16.6; P < 0.001]. A positive, although not statistically significant, association persisted after adjustment for age, Gleason grade, and tumor volume (OR 1.9; 95% CI, 0.8-5.1; P = 0.17). In the U.S. study, PNI predicted lethal prostate cancer independent of clinical factors (HR 1.8; 95% CI, 1.0, 3.3; P =0.04).Conclusions: These data support the hypothesis that perineural invasion creates a microenvironment that promotes cancer aggressiveness.Impact: Our findings suggest that PNI should be a standardized component of histopathologic review, and highlights a mechanism underlying prostate cancer metastasis. Cancer Epidemiol Biomarkers Prev; 26(5); 719-26. ©2017 AACR.

Abstract 60: PTEN expression, cholesterol metabolism, and lethal prostate cancer

BACKGROUND: We previously showed that mRNA expression of squalene monooxygenase (SQLE), part of the cholesterol synthesis pathway, is associated with lethal prostate cancer. In-vitro studies suggest that loss of PTEN expression and resulting PI3K pathway activation drive cholesterol ester accumulation in aggressive prostate cancers through sterol regulatory element-binding protein (SREBP) and acyl coenzyme A-cholesterol acyltransferase (ACAT1) activity. In two prospective cohorts, we studied whether lower PTEN expression is associated with cholesterol metabolism and how this relates to lethal prostate cancer.

METHODS: We analyzed men with prostate cancer from the prospective prostatectomy Health Professionals Follow-up Study and Physicians’ Health Study. 105 men had lethal cancer and 284 men non-lethal disease without metastases at 8 years of follow-up. Whole-transcriptome mRNA expression profiling data was available from diagnostic prostate tumor specimens. Linear regression models were used to assess continuous and categorical associations, and Pearson correlation coefficients were calculated. Logistic regression was used to obtain odds ratios (ORs) and 95% confidence intervals (CIs) of lethal prostate cancer.

RESULTS: Both lower PTEN and higher SQLE expression were associated with higher Gleason grade (p trend &lt; 0.001 each). Correlations of PTEN with SREBF1 (r = -0.08, p = 0.1), SREBF2 (r = -0.09, p = 0.07), and ACAT1 (r = 0.04, p = 0.4) were weak. SREBF2 was correlated with SQLE (r = 0.33, p &lt; 0.001) but not with ACAT1 (r = -0.01, p = 0.8). Low PTEN was associated with lethal cancer (OR, 1.50 per 1 standard deviation [SD] decrease; 95% CI, 1.20 to 1.87; p = 0.001). High SQLE was associated with lethal cancer (OR 2.13 per 1 SD increase, 95% CI, 1.63 to 2.79; p &lt; 0.001). SREBF1, SREBF2, and ACAT1 were not associated with lethal cancer (all p &gt; 0.05). Adjusting for PTEN mildly attenuated the association of SQLE with lethal cancer (OR, 2.07; 95% CI, 1.57 to 2.73), as did additional adjustment for age, Gleason grade, and stage (SQLE: OR, 1.75; 95% CI, 1.29 to 2.40). In the lowest quartile of PTEN expression, SQLE was less strongly associated with lethal cancer (OR 1.74; 95% CI, 1.20 to 2.52) compared to the upper three quartiles (OR 2.47; 95% CI, 1.69 to 3.60; p interaction = 0.2).

CONCLUSION: Low PTEN mRNA expression and high SQLE are features of aggressive prostate cancers. However, at the time of prostatectomy, SREBF1/2 expression and resulting ACAT1 expression do not appear to be major characteristics of prostate cancers with lethal outcomes.

Citation Format: Konrad H. Stopsack, Travis A. Gerke, Lorelei A. Mucci, Jennifer R. Rider. PTEN expression, cholesterol metabolism, and lethal prostate cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 60.

Abstract 2543: A family affair: Prostate cancer risk and family history of breast or prostate cancer

Background - There is suggestive evidence of familial clustering of breast and prostate cancer in first-degree relatives; women with a family history of prostate cancer are at increased risk of breast cancer. Few studies have investigated joint family history of breast and prostate cancer and prostate cancer risk, and no study to date has examined lethal prostate cancer.

Methods - We studied 42,672 from the Health Professionals Follow-up Study between 1996 to 2012. During follow-up, 4,258 prostate cancer cases were diagnosed, of whom 380 were lethal disease. Men self-reported family history of breast and prostate cancer, including in siblings or parents. Using cause-specific hazards regression, we estimated hazard ratios (HR) and 95% confidence intervals (CI) of the association between family history and prostate cancer risk and progression.

Results - About 8% of men had a family history of prostate cancer, 8.7% had a family history of breast cancer, and 1.4% of men had a family history of both breast and prostate cancer. A family history of prostate cancer was significantly associated with an increased risk of prostate cancer (HR: 1.69; 95% CI: 1.54-1.85). Increased risk was higher for men with a father diagnosed with prostate cancer (HR: 1.64 95% CI: 1.49-1.80) than for men with a diagnosis in a brother(s) (HR: 1.51 95% CI: 1.27-1.80). A positive family history of breast cancer was associated with a small, but significant 22% increased risk (HR: 1.22; 95% CI: 1.11-1.35). Familial breast cancer in a sister (HR: 1.22 95% CI: 1.06-1.41) increased risk more than familial breast cancer in a mother (HR: 1.12; 95% CI: 0.99-1.25). Men with a family history of both prostate and breast cancer had a 52% (HR: 1.52; 95%CI: 1.23-1.88) increased risk of prostate cancer compared to men with no family history of either cancer. Risk of lethal prostate cancer was also significantly increased for men with a positive family history of prostate cancer (HR: 1.64; 95% CI: 1.20-2.24), as well as for men with a family history of breast cancer (HR: 1.47; 95% CI: 1.07-2.01).

Conclusions - These results support the findings of familial aggregation of breast and prostate cancer, and for the first time suggest an association between familial breast cancer and lethal prostate cancer. Data from this prospective study have translational relevance for family counseling of cancer patients.

Citation Format: Lauren E. Barber, Travis A. Gerke, Sarah C. Markt, Giovanni Parmigiani, Lorelei A. Mucci. A family affair: Prostate cancer risk and family history of breast or prostate cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2543.

Cholesterol Metabolism and Prostate Cancer Lethality

Cholesterol metabolism has been implicated in prostate cancer pathogenesis. Here, we assessed the association of intratumoral mRNA expression of cholesterol synthesis enzymes, transporters, and regulators in tumor specimen at diagnosis and lethal prostate cancer, defined as mortality or metastases from prostate cancer in contrast to nonlethal disease without evidence of metastases after at least 8 years of follow-up. We analyzed the prospective prostate cancer cohorts within the Health Professionals Follow-up Study (n = 249) and the Physicians' Health Study (n = 153) as well as expectantly managed patients in the Swedish Watchful Waiting Study (n = 338). The expression of squalene monooxygenase (SQLE) was associated with lethal cancer in all three cohorts. Men with high SQLE expression (>1 standard deviation above the mean) were 8.3 times (95% confidence interval, 3.5 to 19.7) more likely to have lethal cancer despite therapy compared with men with the mean level of SQLE expression. Absolute SQLE expression was associated with lethal cancer independently from Gleason grade and stage, as was a SQLE expression ratio in tumor versus surrounding benign prostate tissue. Higher SQLE expression was tightly associated with increased histologic markers of angiogenesis. Collectively, this study establishes the prognostic value of intratumoral cholesterol synthesis as measured via SQLE, its second rate-limiting enzyme. SQLE expression at cancer diagnosis is prognostic for lethal prostate cancer both after curative-intent prostatectomy and in a watchful waiting setting, possibly by facilitating micrometastatic disease. Cancer Res; 76(16); 4785-90. ©2016 AACR.

Evaluating a 4-marker signature of aggressive prostate cancer using time-dependent AUC

BACKGROUND

We previously identified a protein tumor signature of PTEN, SMAD4, SPP1, and CCND1 that, together with clinical features, was associated with lethal outcomes among prostate cancer patients. In the current study, we sought to validate the molecular model using time-dependent measures of AUC and predictive values for discriminating lethal from non-lethal prostate cancer.

METHODS

Using data from the initial study, we fit survival models for men with prostate cancer who were participants in the Physicians' Health Study (PHS; n = 276). Based on these models, we generated prognostic risk scores in an independent population, the Health Professionals Follow-up Study (HPFS; n = 347) to evaluate external validity. In each cohort, men were followed prospectively from cancer diagnosis through 2011 for development of distant metastasis or cancer mortality. We measured protein tumor expression of PTEN, SMAD4, SPP1, and CCND1 on tissue microarrays.

RESULTS

During a median of 11.9 and 14.3 years follow-up in the PHS and HPFS cohorts, 24 and 32 men (9%) developed lethal disease. When used as a prognostic factor in a new population, addition of the four markers to clinical variables did not improve discriminatory accuracy through 15 years of follow-up.

CONCLUSIONS

Although the four markers have been identified as key biological mediators in metastatic progression, they do not provide independent, long-term prognostic information beyond clinical factors when measured at diagnosis. This finding may underscore the broad heterogeneity in aggressive prostate tumors and highlight the challenges that may result from overfitting in discovery-based research.