Late-stage Prostate Cancer Research Articles

Abstract A046: Disparities in cancer burden and survival rates in persistent poverty communities in Los Angeles County

Abstract Objective: Persistent poverty census tracts (PPT) are those with socioeconomic challenges where prolonged economic disadvantages may significantly influence health outcomes. This study examined the cancer burden and survival patterns in PPTs compared to non-PPTs in Los Angeles County (LAC) considering disparities by race/ethnicity and stage at diagnosis. Methods: A comprehensive analysis of 2012-2021 Cancer Registry data examined age-adjusted incidence rates (AAIRs) and survival rates for lung, colorectal, liver, stomach, breast, and prostate cancers, which are the Norris Comprehensive Cancer Center priority cancers. Cancer-specific data were further stratified by racial/ethnic group and stage at diagnosis, and compared across residents in PPTs, non-PPTs, and LAC overall. Survival rates were calculated using the Kaplan-Meier method and differences between groups were assessed by log-rank tests. Results: PPTs in LAC were characterized by a higher proportion of racial/ethnic minorities, lower education levels, and higher unemployment compared to non-PPTs. In all racial/ethnic groups combined, AAIRs for lung, breast, and prostate cancers were lower in PPTs than non-PPTs, whereas AAIRS for liver and stomach cancers were higher in PPTs, with no differences for colorectal cancer. Disparities emerged when considering race and ethnicity, with higher lung cancer AAIRs among Non-Hispanic White (NHW) and Black/African American (B/AA) PPT residents compared to non-PPT, while AAIRs for lung and colorectal cancers were lower among Hispanic/Latino (H/L) PPT residents compared to non-PPTs. Breast and prostate cancer AAIRs remained lower in PPTs than in non-PPTS regardless of racial/ethnic group. Patients in PPTs exhibit significantly lower five-year survival rates across all studied cancers, except stomach, compared to non-PPTs. B/AA patients showed the lowest five-year survival rates for lung and colorectal cancer, with patients in PPTs experiencing significantly lower rates than patients in non-PPTs regardless of disease stage (p < 0.01 for early- or late-stage). Liver cancer survival rates were notably low, especially for H/L and Asian/Pacific Islander patients in PPTs, with five-year survival for late-stage cancer at 4.9% (95%CI: 2.8-8.5) and 5.4% (95%CI: 2.1-14.0), respectively. Patients in PPTs with late-stage breast or prostate cancer exhibited significantly lower 5-year survival (compared to non-PPTs) across all race/ethnicities, with B/AA patients experiencing the lowest survival rates for breast cancer and NHW patients experiencing the lowest survival rates for prostate cancer. Conclusions: Cancer outcomes for patients in PPTs were significantly poorer compared to those in non-PPT communities. The notably lower AAIRs in PPTs versus non-PPTs for more screen-able cancers, such as breast, prostate, and early-stage colorectal cancer, suggest a need for greater efforts to provide access to routine screening in areas affected by persistent poverty, though other causes cannot be ruled out. Citation Format: Miriam L Gorbatov, Joel S. Mendez, Myles Cockburn, Laura K. Thompson, Lihua Liu, Jennifer Tsui, Kali Zhou, V. Wendy Setiawan, Chanita Hughes-Halbert, Mariana C. Stern. Disparities in cancer burden and survival rates in persistent poverty communities in Los Angeles County [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr A046.

Polyploid cancer cells reveal signatures of chemotherapy resistance.

Therapeutic resistance in cancer significantly contributes to mortality, with many patients eventually experiencing recurrence after initial treatment responses. Recent studies have identified therapy-resistant large polyploid cancer cells in patient tissues, particularly in late-stage prostate cancer, linking them to advanced disease and relapse. Here, we analyzed bone marrow aspirates from 44 advanced prostate cancer patients and found the presence of circulating tumor cells with increased genomic content (CTC-IGC) was significantly associated with poorer progression-free survival. Single cell copy number profiling of CTC-IGC displayed clonal origins with typical CTCs, suggesting complete polyploidization. Induced polyploid cancer cells from PC3 and MDA-MB-231 cell lines treated with docetaxel or cisplatin were examined through single cell DNA sequencing, RNA sequencing, and protein immunofluorescence. Novel RNA and protein markers, including HOMER1, TNFRSF9, and LRP1, were identified as linked to chemotherapy resistance. These markers were also present in a subset of patient CTCs and associated with recurrence in public gene expression data. This study highlights the prognostic significance of large polyploid tumor cells, their role in chemotherapy resistance, and their expression of markers tied to cancer relapse, offering new potential avenues for therapeutic development.

Impacts of Interleukin-10 Promoter Genotypes on Prostate Cancer.

Prostate cancer (PCa) is a multifactorial disease influenced by genetic, environmental, and immunological factors. Genetic polymorphisms in the interleukin-10 (IL-10) gene have been implicated in PCa susceptibility, development, and progression. This study aims to assess the contributions of three IL-10 promoter single nucleotide polymorphisms (SNPs), A-1082G (rs1800896), T-819C (rs3021097), and A-592C (rs1800872), to the risk of PCa in Taiwan. The three IL-10 genotypes were determined using PCR-RFLP methodology and were evaluated for their contributions to PCa risk among 218 PCa patients and 436 non-PCa controls. None of the three IL-10 SNPs were significantly associated with the risks of PCa (p all > 0.05) in the overall analyses. However, the GG at rs1800896 combined with smoking behavior was found to significantly increase the risk of PCa by 3.90-fold (95% confidence interval [95% CI] = 1.28-11.89, p = 0.0231). In addition, the rs1800896 AG and GGs were found to be correlated with the late stages of PCa (odds ratio [OR] = 1.90 and 6.42, 95% CI = 1.05-3.45 and 2.30-17.89, p = 0.0452 and 0.0003, respectively). The IL-10 promoter SNP, A-1082G (rs1800896), might be a risk factor for PCa development among smokers and those at late stages of the disease. These findings should be validated in larger and more diverse populations.

The Influence of Disparities on Prostate Cancer at Diagnosis in the Charlotte Metropolitan Area.

Prostate cancer (PCa) is the most diagnosed noncutaneous malignancy and second leading-cause of cancer death in men, yet screening is decreasing. As PCa screening has become controversial, socioeconomic disparities in PCa diagnosis and outcomes widen. This study was designed to determine the current disparities influencing PCa diagnosis in Charlotte, NC. The Levine Cancer Institute database was queried for patients with PCa, living in metropolitan Charlotte. Socioeconomic status (SES) was determined by the Area Deprivation Index (ADI); higher ADI indicated lower SES. Patients were compared by their National Comprehensive Cancer Network risk stratification. Artificial intelligence predictive models were trained and heatmaps were created, demonstrating the geographic and socioeconomic disparities in late-stage PCa. Of the 802 patients assessed, 202 (25.2%) with high-risk PCa at diagnosis were compared with 198 (24.7%) with low-risk PCa. High-risk PCa patients were older (69.8±9.0 vs. 64.0±7.9 years; p<0.001) with lower SES (ADI block: 98.4±20.9 vs. 92.1±19.8; p=0.004) and more commonly African-American (White: 66.2% vs. 78.3%, African-American: 31.3% vs. 20.7%; p=0.009). On regression, ADI block was an independent predictor (odds ratio [OR]=1.013, 95% confidence interval [CI] 1.002-1.024; p=0.024) of high-risk PCa at diagnosis, whereas race was not (OR=1.312, 95% CI 0.782-2.201; p=0.848). A separate regression demonstrated higher ADI (OR=1.016, 95% CI 1.004-1.027; p=0.006) and older age (OR=1.083, 95% CI 1.054-1.114; p<0.001) were independent predictors for high-risk PCa. Findings, depicted in heatmaps, demonstrated the geographic locations where men with PCa were predicted to have high-risk disease based on their age and SES. Socioeconomic status was more closely associated with high-risk PCa at diagnosis than race. Although, of any variable, age was most predictive. The heatmaps identified areas that would benefit from increased awareness, education, and screening to facilitate an earlier PCa diagnosis.

Combining PSMA-PET and PROMISE to re-define disease stage and risk in patients with prostate cancer: a multicentre retrospective study

Prostate-specific membrane antigen (PSMA)-PET was introduced into clinical practice in 2012 and has since transformed the staging of prostate cancer. Prostate Cancer Molecular Imaging Standardized Evaluation (PROMISE) criteria were proposed to standardise PSMA-PET reporting. We aimed to compare the prognostic value of PSMA-PET by PROMISE (PPP) stage with established clinical nomograms in a large prostate cancer dataset with follow-up data for overall survival. In this multicentre retrospective study, we used data from patients of any age with histologically proven prostate cancer who underwent PSMA-PET at the University Hospitals in Essen, Münster, Freiburg, and Dresden, Germany, between Oct 30, 2014, and Dec 27, 2021. We linked a subset of patient hospital records with patient data, including mortality data, from the Cancer Registry North-Rhine Westphalia, Germany. Patients from Essen University Hospital were randomly assigned to the development or internal validation cohorts (2:1). Patients from Münster, Freiburg, and Dresden University Hospitals were included in an external validation cohort. Using the development cohort, we created quantitative and visual PPP nomograms based on Cox regression models, assessing potential PPP predictors for overall survival, with least absolute shrinkage and selection operator penalty for overall survival as the primary endpoint. Performance was measured using Harrell's C-index in the internal and external validation cohorts and compared with established clinical risk scores (International Staging Collaboration for Cancer of the Prostate [STARCAP], European Association of Urology [EAU], and National Comprehensive Cancer Network [NCCN] risk scores) and a previous nomogram defined by Gafita et al (hereafter referred to as GAFITA) using receiver operating characteristic (ROC) curves and area under the ROC curve (AUC) estimates. We analysed 2414 male patients (1110 included in the development cohort, 502 in the internal cohort, and 802 in the external validation cohort), among whom 901 (37%) had died as of data cutoff (June 30, 2023; median follow-up of 52·9 months [IQR 33·9-79·0]). Predictors in the quantitative PPP nomogram were locoregional lymph node metastases (molecular imaging N2), distant metastases (extrapelvic nodal metastases, bone metastases [disseminated or diffuse marrow involvement], and organ metastases), tumour volume (in L), and tumour mean standardised uptake value. Predictors in the visual PPP nomogram were distant metastases (extrapelvic nodal metastases, bone metastases [disseminated or diffuse marrow involvement], and organ metastases) and total tumour lesion count. In the internal and external validation cohorts, C-indices were 0·80 (95% CI 0·77-0·84) and 0·77 (0·75-0·78) for the quantitative nomogram, respectively, and 0·78 (0·75-0·82) and 0·77 (0·75-0·78) for the visual nomogram, respectively. In the combined development and internal validation cohort, the quantitative PPP nomogram was superior to STARCAP risk score for patients at initial staging (n=139 with available staging data; AUC 0·73 vs 0·54; p=0·018), EAU risk score at biochemical recurrence (n=412; 0·69 vs 0·52; p<0·0001), and NCCN pan-stage risk score (n=1534; 0·81 vs 0·74; p<0·0001) for the prediction of overall survival, but was similar to GAFITA nomogram for metastatic hormone-sensitive prostate cancer (mHSPC; n=122; 0·76 vs 0·72; p=0·49) and metastatic castration-resistant prostate cancer (mCRPC; n=270; 0·67 vs 0·75; p=0·20). The visual PPP nomogram was superior to EAU at biochemical recurrence (n=414; 0·64 vs 0·52; p=0·0004) and NCCN across all stages (n=1544; 0·79 vs 0·73; p<0·0001), but similar to STARCAP for initial staging (n=140; 0·56 vs 0·53; p=0·74) and GAFITA for mHSPC (n=122; 0·74 vs 0·72; p=0·66) and mCRPC (n=270; 0·71 vs 0·75; p=0·23). Our PPP nomograms accurately stratify high-risk and low-risk groups for overall survival in early and late stages of prostate cancer and yield equal or superior prediction accuracy compared with established clinical risk tools. Validation and improvement of the nomograms with long-term follow-up is ongoing (NCT06320223). Cancer Registry North-Rhine Westphalia.

Cell Membrane-Camouflaged Chitosan-Polypyrrole Nanogels Co-Deliver Drug and Gene for Targeted Chemotherapy and Bone Metastasis Inhibition of Prostate Cancer.

The development of functional nanoplatforms to improve the chemotherapy outcome and inhibit distal cancer cell metastasis remains an extreme challenge in cancer management. In this work, a human-derived PC-3 cancer cell membrane-camouflaged chitosan-polypyrrole nanogel (CH-PPy NG) platform, which can be loaded with chemotherapeutic drug docetaxel (DTX) and RANK siRNA for targeted chemotherapy and gene silencing-mediated metastasis inhibition of late-stage prostate cancer in a mouse model, is reported. The prepared NGs with a size of 155.8nm show good biocompatibility, pH-responsive drug release profile, and homologous targeting specificity to cancer cells, allowing for efficient and precise drug/gene co-delivery. Through in-vivo antitumor treatment in a xenografted PC-3 mouse tumor model, it is shown that such a CH-PPy NG-facilitated co-delivery system allows for effective chemotherapy to slow down the tumor growth rate, and effectively inhibits the metastasis of prostate cancer to the bone via downregulation of the RANK/RANKL signaling pathway. The created CH-Ppy NGs may be utilized as a promising platform for enhanced chemotherapy and anti-metastasis treatment of prostate cancer.

CDK9 inhibition activates innate immune response through viral mimicry.

Cancer cells frequently exhibit hyperactivation of transcription, which can lead to increased sensitivity to compounds targeting the transcriptional kinases, in particular CDK9. However, mechanistic details of CDK9 inhibition-induced cancer cell-selective anti-proliferative effects remain largely unknown. Here, we discover that CDK9 inhibition activates the innate immune response through viral mimicry in cancer cells. In MYC over-expressing prostate cancer cells, CDK9 inhibition leads to the gross accumulation of mis-spliced RNA. Double-stranded RNA (dsRNA)-activated kinase can recognize these mis-spliced RNAs, and we show that the activity of this kinase is required for the CDK9 inhibitor-induced anti-proliferative effects. Using time-resolved transcriptional profiling (SLAM-seq), targeted proteomics, and ChIP-seq, we show that, similar to viral infection, CDK9 inhibition significantly suppresses transcription of most genes but allows selective transcription and translation of cytokines related to the innate immune response. In particular, CDK9 inhibition activates NFκB-driven cytokine signaling at the transcriptional and secretome levels. The transcriptional signature induced by CDK9 inhibition identifies prostate cancers with a high level of genome instability. We propose that it is possible to induce similar effects in patients using CDK9 inhibition, which, we show, causes DNA damage invitro. In the future, it is important to establish whether CDK9 inhibitors can potentiate the effects of immunotherapy against late-stage prostate cancer, a currently lethal disease.

Abstract 448: Alterations in glycolytic pathway enzymes and metabolic plasticity in prostate cancer progression

Abstract Background: Although oxidative phosphorylation (OXPHOS) is the main ATP source in primary prostate cancer, as the tumor progresses to castration resistance and/or metastatic disease, glycolysis becomes increasingly prevalent. Dependence on glycolysis can further increase under hypoxic conditions found in advanced cancers. We previously demonstrated that a novel small molecule, BKIDC-1553, inhibits proliferation and tumor growth of prostate cancer cell lines and xenografts through a hexokinase-2 (HK2) dependent inhibition of glycolysis. HK2 is a glucose 6-phosphorylating enzyme that works in conjunction with glucose transporter-1 (GLUT1) to drive glycolysis in cells. While our previous work suggests that BKIDC-1553 works primarily through a HK2 dependent mechanism, the objective of this current project is to further examine how expression and function of HK2 and GLUT1 are altered in response to BKIDC-1553 treatment. Methods: Hypoxic conditions are common in late-stage prostate cancer. Effects of hypoxia on cell proliferation and expression levels of HK1, HK2, and GLUT1 were examined with and without BKIDC-1553 treatment. To examine role of HK1, HK2, and GLUT1 in response to BKIDC-1553 treatment, we created CRISPR knockouts and shRNA knockdowns of HK1 and HK2 in the LNCaP prostate cancer cell line. GLUT1 was inhibited using a commercially available inhibitor, BAY-876. PCR and Western blots were used to confirm expression levels of HK1, HK2, and GLUT1. MTS proliferation assays were used to examine effect of KO and KD on response to BKIDC-1553 and BAY-876. Results: GLUT1 levels, but not HK1 or 2, increased at 72 hrs under hypoxic conditions. HK1, HK2, and GLUT1 levels all increased in cells in response to 144 hrs of BKIDC-1553 compared with 72 hrs treatment in both normoxic and hypoxic conditions. The KO and KD studies were all conducted in normoxic conditions. Westerns blots demonstrated that HK2 KO, but not HK1 KO, results in increased levels of GLUT1. HK1 or HK2 KD, however, did not alter GLUT1 levels. HK2 KD cells, with GLUT1 levels remaining the same, displayed less growth inhibition than control cells in response to BKIDC-1553 treatment, while HK2 KO cells, with increased levels of GLUT1, remained sensitive to BKIDC-1553. Because GLUT1 levels increase in response to HK2 KO, we wanted to see if inhibiting GLUT1 in these cells could decrease their proliferation. We found that KO cells were indeed more sensitive to growth inhibition of BAY-876. Conclusion/Summary: These studies indicate that KO of HK2 increases levels of GLUT1. These cells remain sensitive to BKIDC-1553 treatment, which could in part be due to the cells' continued reliance on glycolysis through increased GLUT1. A continued reliance on glycolysis allows BKIDC-1553 to continue to inhibit cell growth. Future studies examining how combination treatment with BKIDC-1553 and BAY-876 affects growth of advanced prostate cancer cells is underway. Citation Format: Cynthia Sprenger, Mika Munari, Shihua Sun, Kathryn Soriano Epilepsia, Stephen Plymate. Alterations in glycolytic pathway enzymes and metabolic plasticity in prostate cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 448.

Abstract 528: CDK9 inhibition activates innate immune response in prostate cancer cells

Abstract Hyper-activation of transcription is frequent in cancer, which often leads to increased sensitivity to compounds targeting the transcriptional kinases, in particular cyclin-dependent kinase 9 (CDK9). However, mechanistic details as to why CDK9 inhibition selectively kills cancer cells remain largely unknown. Here, we report that CDK9 inhibition activates innate immune response through viral mimicry. In MYC over-expressing prostate cancer cells, CDK9 inhibition leads to excessive accumulation of mis-spliced RNA. Double-stranded RNA (dsRNA)-activated kinase can recognize these mis-spliced RNAs, and we show that this kinase is required for the CDK9 inhibitor-induced anti-proliferative effects. Using time-resolved transcriptional profiling (SLAM-seq), targeted proteomics and ChIP-seq, we show that, similar to viral infection, CDK9 inhibition significantly suppresses transcription of most genes but allows selective transcription and translation of certain genes. In particular, CDK9 inhibition activates NFκB-driven cytokine-signaling at the transcriptional- and secretome-levels. Transcriptional signature induced by CDK9 inhibition identifies prostate cancers with high level of genome instability, and we propose that it is possible to induce similar effects using CDK9 inhibitors. In summary, here we show that inhibition of CDK9 activates innate immune response through viral mimicry. In the future, it is important to establish if CDK9 inhibitors can potentiate the effects of immunotherapy against the late-stage prostate cancer, a currently lethal disease. Citation Format: Shivani Yalala, Aishwarya Gondane, Ninu Poulose, Jing Liang, Ian G. Mills, Harri M. Itkonen. CDK9 inhibition activates innate immune response in prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 528.

MiRNA Expression Patterns in Early- and Late-Stage Prostate Cancer Patients: High-Throughput Analysis.

Prostate cancer (PCa) is one of the most common types of cancer among men. To date, there have been no specific markers identified for the diagnosis and prognosis or response to treatment of this disease. Thus, there is an urgent need for promising markers, which may be fulfilled by small non-coding RNAs known as microRNAs (miRNAs). Therefore, the present study aimed to investigate the miRNA profile in tissue samples obtained from patients with PCa using microarrays, followed by reverse transcriptase quantitative PCRs (RT-qPCRs). In the discovery phase, 754 miRNAs were screened in tissues obtained from patients (n = 46) with PCa in early and late stages. Expression levels of miRNA-324-3p, miRNA-429, miRNA-570, and miRNA-616 were found to be downregulated, and miRNA-423-5p expression was upregulated in patients with early-stage cancer compared to the late-stage ones. These five miRNAs were further validated in an independent cohort of samples (n = 39) collected from patients with PCa using RT-qPCR-based assays. MiRNA-324-3p, miRNA-429, miRNA-570, and miRNA-616 expression levels remained significantly downregulated in early-stage cancer tissues compared to late-stage tissues. Remarkably, for a combination of three miRNAs, PSA levels and Gleason scores were able to discriminate between patients with early-stage PCa and late-stage PCa, with an AUC of 95%, a sensitivity of 86%, and a specificity close to 94%. Thus, the data obtained in this study suggest a possible involvement of the identified miRNAs in the pathogenesis of PCa, and they may also have the potential to be developed into diagnostic and prognostic tools for PCa. However, further studies with a larger cohort are needed.

MED19 encodes two unique protein isoforms that confer prostate cancer growth under low androgen through distinct gene expression programs

MED19, a component of the mediator complex and a co-regulator of the androgen receptor (AR), is pivotal in prostate cancer cell proliferation. MED19 has two isoforms: a full-length “canonical” and a shorter “alternative” variant. Specific antibodies were developed to investigate these isoforms. Both exhibit similar expression in normal prostate development and adult prostate tissue, but the canonical isoform is elevated in prostate adenocarcinomas. Overexpression of canonical MED19 in LNCaP cells promotes growth under conditions of androgen deprivation in vitro and in vivo, mirroring earlier findings with alternative MED19-overexpressing LNCaP cells. Interestingly, alternative MED19 cells displayed strong colony formation in clonogenic assays under conditions of androgen deprivation, while canonical MED19 cells did not, suggesting distinct functional roles. These isoforms also modulated gene expression differently. Canonical MED19 triggered genes related to extracellular matrix remodeling while suppressing those involved in androgen-inactivating glucuronidation. In contrast, alternative MED19 elevated genes tied to cell movement and reduced those associated with cell adhesion and differentiation. The ratio of MED19 isoform expression in prostate cancers shifts with the disease stage. Early-stage cancers exhibit higher canonical MED19 expression than alternative MED19, consistent with canonical MED19’s ability to promote cell proliferation under androgen deprivation. Conversely, alternative MED19 levels were higher in later-stage metastatic prostate cancer than in canonical MED19, reflecting alternative MED19’s capability to enhance cell migration and autonomous cell growth. Our findings suggest that MED19 isoforms play unique roles in prostate cancer progression and highlights MED19 as a potential therapeutic target for both early and late-stage prostate cancer.

THU479 FOXA1 Loss Remodels The Tumor Immune Microenvironment In Late-stage Prostate Cancer

Abstract Disclosure: L.T. Brea: None. H. Shi: None. V. Keo: None. W. Xie: None. X. Lu: None. G. Gritsina: None. X. Wang: None. S.H. Park: None. J. Zhao: None. J. Yu: None. Background: Castration resistant prostate cancer (CRPC) has shown a poor response to immune checkpoint inhibitors due to its immunosuppressive nature. CRPC is infiltrated by tumor-associated macrophages (TAMs) and T regulatory cells (Tregs), which induce an immunosuppressive tumor immune microenvironment (TIME) and promote tumor progression. A deeper understanding of tumor intrinsic mechanisms shaping the TIME in prostate cancer (PCa) is needed to harness immunotherapies for PCa patients. Previous studies have found that epithelial transcription factor FOXA1 is downregulated in CRPC. In accordance, we have reported that FOXA1 loss induces tumor cell invasion and macrophage recruitment in vitro through HIF1A-CCL2 signaling. However, the extent to which FOXA1 loss regulates the TIME in PCa remains unclear, largely due to the lack of immune-proficient mouse models for the study of FOXA1 function in the context of PCa. Methods: To examine how FOXA1 loss regulates the PCa TIME, we generated a novel genetically engineered mouse model (GEMM) with prostate-specific deletion of Pten and Foxa1 (PbCre4:Ptenf/fFoxa1f/f) to compare with the established Pten-null PCa mouse model (PbCre4:Ptenf/f). We performed immunohistochemistry analyses on the GEMM prostate tumor tissues to characterize histopathology changes and assess tumor immune infiltration. We also performed spatial transcriptomics and scRNA-seq analyses of the GEMMs to comprehensively evaluate the effect of Foxa1 loss on downstream pathways and the surrounding TIME. Finally, we performed bioinformatics analysis of PCa patient datasets to validate the clinical relevance. Results: We found PbCre4:Ptenf/fFoxa1f/f mouse prostate tumors exhibited a more aggressive histopathologic tumor phenotype compared to age-matched PbCre4:Ptenf/f. Notably, immunohistochemistry staining and spatial transcriptomic analysis of the GEMMs revealed striking remodeling of the TIME upon Foxa1 loss, with marked increases in tumor infiltration by Tregs and TAMs. Moreover, CIBERSORTx analysis of patient datasets revealed FOXA1 expression negatively correlates with Treg and M2-macrophage infiltration. We also found pro-tumorigenic inflammatory cytokine signaling genes, linked to the recruitment of immunosuppressive cells, were upregulated in PbCre4:Ptenf/fFoxa1f/f prostate tumors. Furthermore, we confirmed inflammatory pathways were upregulated among FOXA1-low patient samples. Additional studies are ongoing to further elucidate the mechanisms by which FOXA1 regulates inflammatory cytokine signaling and the TIME in PCa.Conclusion: This study presents a novel GEMM for the study of FOXA1 function in an immunocompetent setting. Our data supports FOXA1 as a critical tumor intrinsic regulator of the TIME. This will have important implications on the design of immunotherapeutic approaches for late-stage PCa often with FOXA1 loss. Presentation: Thursday, June 15, 2023

GRPR versus PSMA: expression profiles during prostate cancer progression demonstrate the added value of GRPR-targeting theranostic approaches.

Central to targeted radionuclide imaging and therapy of prostate cancer (PCa) are prostate-specific membrane antigen (PSMA)-targeting radiopharmaceuticals. Gastrin-releasing peptide receptor (GRPR) targeting has been proposed as a potential additional approach for PCa theranostics. The aim of this study was to investigate to what extent and at what stage of the disease GRPR-targeting applications can complement PSMA-targeting theranostics in the management of PCa. Binding of the GRPR- and PSMA-targeting radiopharmaceuticals [177Lu]Lu-NeoB and [177Lu]Lu-PSMA-617, respectively, was evaluated and compared on tissue sections of 20 benign prostatic hyperplasia (BPH), 16 primary PCa and 17 progressive castration-resistant PCa (CRPC) fresh frozen tissue specimens. Hematoxylin-eosin and alpha-methylacyl-CoA racemase stains were performed to identify regions of prostatic adenocarcinoma and potentially high-grade prostatic intraepithelial neoplasia. For a subset of primary PCa samples, RNA in situ hybridization (ISH) was used to identify target mRNA expression in defined tumor regions. The highest median [177Lu]Lu-NeoB binding was observed in primary PCa samples, while median and overall [177Lu]Lu-PSMA-617 binding was highest in CRPC samples. The highest [177Lu]Lu-NeoB binding was observed in 3/17 CRPC samples of which one sample showed no [177Lu]Lu-PSMA-617 binding. RNA ISH analyses showed a trend between mRNA expression and radiopharmaceutical binding, and confirmed the distinct GRPR and PSMA expression patterns in primary PCa observed with radiopharmaceutical binding. Our study emphasizes that GRPR-targeting approaches can contribute to improved PCa management and complement currently applied PSMA-targeting strategies in both early and late stage PCa.

An 86-Year-Old Male with Metastasized Cancer Treated with External Beam Radiation Therapy: A Case Report from Zimbabwe

Prostate cancer is the most common malignancy diagnosed in men and the second most common cause of cancer deaths in men. Incidence increases drastically after the age of 50, however, it is more common in males above the age of 65. Prostatic cancer is asymptomatic in its early stages, i.e., when it is still localized, hence most patients present with late-stage cancers. Patients with late-stage prostate cancer usually present with urethral obstruction, nocturia, narrow stream, and they rarely present with pain or stiffness caused by bony metastases. The common treatment for late-stage prostate cancer is hormonal therapy. We herein present a case of an 86-year-old male who presented with metastasized prostate cancer. The cancer had metastasized to the head of the femur and there was bone fracture in the neck of the femur as well. The patient received external beam radiotherapy as palliative treatment due to the limited resources in Zimbabwe. The patient did not come for follow up review and hence it was not possible to conclude whether the external beam treatment was an effective palliative treatment. The learning points in this case are as follows: stage at presentation of man with cancer of the prostate in comparison with what literature say, management done in comparison to the recommended management guidelines, follow up strategies to minimize patients absconding follow up reviews and how loss of follow up to patients treated affect future evidence-based management of patients.

Diabetes and Prostate Cancer Outcomes in Men with Nonmetastatic Castration-Resistant Prostate Cancer: Results from the SEARCH Cohort.

The prognosis of diabetic men with advanced prostate cancer is poorly understood and understudied. Hence, we studied associations between diabetes and progression to metastases, prostate cancer-specific mortality (PCSM) and all-cause mortality (ACM) in men with nonmetastatic castration-resistant prostate cancer (nmCRPC). Data from men diagnosed with nmCRPC between 2000 and 2017 at 8 Veterans Affairs Health Care Centers were analyzed using Cox regression to determine HRs and 95% confidence intervals (CI) for associations between diabetes and outcomes. Men with diabetes were classified according to: (i) ICD-9/10 codes only, (ii) two HbA1c values > 6.4% (missing ICD-9/10 codes), and (iii) all diabetic men [(i) and (ii) combined]. Of 976 men (median age: 76 years), 304 (31%) had diabetes at nmCRPC diagnosis, of whom 51% had ICD-9/10 codes. During a median follow-up of 6.5 years, 613 men were diagnosed with metastases, and 482 PCSM and 741 ACM events occurred. In multivariable-adjusted models, ICD-9/10 code-identified diabetes was inversely associated with PCSM (HR, 0.67; 95% CI, 0.48-0.92) while diabetes identified by high HbA1c values (no ICD-9/10 codes) was associated with an increase in ACM (HR, 1.41; 95% CI, 1.16-1.72). Duration of diabetes, prior to CRPC diagnosis was inversely associated with PCSM among men identified by ICD-9/10 codes and/or HbA1c values (HR, 0.93; 95% CI, 0.88-0.98). In men with late-stage prostate cancer, ICD-9/10 'code-identified' diabetes is associated with better overall survival than 'undiagnosed' diabetes identified by high HbA1c values only. Our data suggest that better diabetes detection and management may improve survival in late-stage prostate cancer.

Histone H2A Lys130 acetylation epigenetically regulates androgen production in prostate cancer

The testicular androgen biosynthesis is well understood, however, how cancer cells gauge dwindling androgen to dexterously initiate its de novo synthesis remained elusive. We uncover dual-phosphorylated form of sterol regulatory element-binding protein 1 (SREBF1), pY673/951-SREBF1 that acts as an androgen sensor, and dissociates from androgen receptor (AR) in androgen deficient environment, followed by nuclear translocation. SREBF1 recruits KAT2A/GCN5 to deposit epigenetic marks, histone H2A Lys130-acetylation (H2A-K130ac) in SREBF1, reigniting de novo lipogenesis & steroidogenesis. Androgen prevents SREBF1 nuclear translocation, promoting T cell exhaustion. Nuclear SREBF1 and H2A-K130ac levels are significantly increased and directly correlated with late-stage prostate cancer, reversal of which sensitizes castration-resistant prostate cancer (CRPC) to androgen synthesis inhibitor, Abiraterone. Further, we identify a distinct CRPC lipid signature resembling lipid profile of prostate cancer in African American (AA) men. Overall, pY-SREBF1/H2A-K130ac signaling explains cancer sex bias and reveal synchronous inhibition of KAT2A and Tyr-kinases as an effective therapeutic strategy.

Abstract A058: Lineage plasticity is associated with an altered MAX cistrome through super-enhancer remodeling

Abstract Background: Roughly 20% of late stage prostate cancer patients display a lineage conversion from typical androgen receptor (AR) driven castrate resistant prostate cancer (CRPC) to a particularly lethal neuroendocrine prostate cancer (NEPC) phenotype as a result of AR pathway inhibition (ARPI). Notably, the mutational landscape of CRPC and NEPC is quite similar, suggesting that epigenetic changes may guide this lineage conversion. Our objective was to explore changes in active epigenetic marks with a particular focus on super-enhancers (SEs) and identify factors that regulate these active regions during lineage plasticity. Methods: We performed ChIP-seq for H3K27ac, H3K4me3 and various TFs in our CRPC and ENZ resistant (ENZR) NEPC-like cell models. We leveraged publicly available H3K27ac data in cell lines as well as PDX models to validate our findings. RNA-seq was integrated with our ChIP-seq results to create a signature which we applied to patient data sets. GIGGLE analysis was used to identify candidate factors at SEs. Results: CRPC and NEPC showed similar active marks at promoters however, enhancer elements were significantly remodeled. We observed extensive remodeling of SEs in our ENZR model compared to CRPC and these unique regions showed greater H3K27ac signals in other ENZR models such as NCI-H660. SE linked genes are associated with stemness pathways and are strongly upregulated as a result of ARPI in vitro, and in vivo. Factor enrichment analysis of these regions showed enrichment for MAX and MYC family binding similar to small cell lung cancer cell lines. ChIPseq for MYC and MAX in our cell models revealed an expansion of MAX binding and contraction of MYC binding in our ENZR model compared to CRPC. In particular, we saw increased binding of MAX at plasticity SEs without MYC suggesting an interaction with MYCL or other factors since MYCN is not expressed in our models. Conclusions: This work improves our understanding of the epigenetic changes that occur during lineage plasticity and ARPI resistance. SE analysis in our models suggests that MAX may be activating these regions with MYCL or independently of the MYC family. MYCL expression is upregulated in NEPC and has higher expression than MYCN suggesting a potential role during lineage plasticity. Citation Format: Maxim Kobelev, Dwaipayan Ganguli, Takeshi Namekawa, Amina Talal, Joshua Scurll, Amina Zoubeidi. Lineage plasticity is associated with an altered MAX cistrome through super-enhancer remodeling [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr A058.

Late-stage prostate cancer and associated socioeconomic and demographic factors: A National Cancer Database Study.

e17115 Background: Prostate cancer accounts for 29% of all cancer diagnoses in men in the United States. A 3% annual increase in the incidence of prostate cancer was reported between 2014 to 2019. The stage at initial presentation significantly impacts the overall mortality of prostate cancer. Current 5-year survival estimates ranged from 99% in early-stage disease to &lt;31% in distant disease. Given this enormous difference in survival rates, we studied the socioeconomic and demographic factors impacting the stage of prostate cancer at diagnosis. We also explored the time trends in the staging of prostate cancer. Methods: Using the National Cancer Database, we identified 1,880,352 patients diagnosed with prostate cancer between 2004 and 2019. We used variables including age at diagnosis, race, insurance status, and year of diagnosis. We used Chi-square tests to determine the association of a variable with staging at diagnosis. Multivariable logistic regression analyses determined the impact of our selected variables on the likelihood of early or late staging at diagnosis. All statistical analyses were performed using SPSS. All tests were performed with a significance level of a = 0.05. Results: In this study, we found that the relative percentage of late-stage diagnoses for blacks 21.5%, Hispanics 24.6% and Asians 25.3% were greater than for Whites 20.7%. Hispanics (OR 1.016) and Asians (OR 1.137) in particular, were more likely to be diagnosed at late stage compared to their white counterparts. Blacks were less likely to be diagnosed at a late stage compared to whites (OR 0.947). Men older than 70 years were more likely to be diagnosed at a late stage than men younger than 60 years (OR 1.149). Insurance status showed the greatest number of late-stage diagnoses in the uninsured 32.4% and Medicaid 31.6% populations while private 19.2% and Medicare 21.9% coverage had lower percentage of late-stage diagnoses. Finally, the year of diagnosis showed large differences in relative percentage of late-stage diagnoses with the 2004-2007 group diagnosing of cases 13.8% at late stage while the 2016-2019 group diagnosed 31.0% at late stage. The probability of having a late-stage diagnosis was higher between 2016-2019 than 2004-2007 (OR 2.724). These results were statistically significant (p&lt;0.001). Conclusions: Old age is associated with late-stage diagnosis. This might be explained by the change in guidelines regarding screening against routine PSA screening in men older than 70 years of age. Since the change in 2008, we have seen a steady increase in the number of late diagnoses. In blacks, there have been some positive strides in late-stage diagnoses as they are less likely to be diagnosed later than whites. However, it is crucial to also pay attention to other groups like Hispanics and Asians that are not considered at increased risk for prostate cancer and hence typically screened less frequently.

Abstract 1243: RON receptor signaling enhances prostate cancer metastasis in Hi-Myc mice

Abstract Prostate cancer (PCa) is the second leading cause of cancer mortality among men globally. Death from PCa is typically due to the lack of effective treatments for advanced forms of prostate cancers including castration-resistant prostate cancer (CRPC) and metastatic prostate cancers (mPCa). Distantly metastasized cancers drop the 5-year survival rate from 98% to 30%. Understanding the intrinsic and extrinsic mechanisms that lead to the development of these advanced prostate cancers could improve treatment options. The RON receptor tyrosine kinase is a cell surface receptor, which is activated by growth factor ligands (HGFL or Gas6), which binding promotes several cancer phenotypes in various cancers including prostate cancer. Our laboratory has shown that RON is overexpressed in 86% of primary and 100% of metastatic human prostate cancers compared to normal prostate tissue. Additionally, we have shown that RON overexpression in the prostates of mice can induce Prostatic intraepithelial neoplasia (PIN) lesions, adenocarcinoma, and increases several cancer phenotypes including proliferation, cell survival, metastasis, and increased recruitment of tumor-associated macrophages. However, we have yet to explore the effect of RON on prostate cancer metastasis. We hypothesize that RON expression enhances metastasis by promoting an increase in the amount of disseminating prostate cancer cells. To test this hypothesis, the Hi-Myc mouse model has been employed. The MYC gene is one of the most dysregulated genes in prostate cancers and Myc expression has been detected in the early stages of prostate cancer development, PIN lesion, and all later stages of prostate cancer. Additionally, the Hi-Myc model is clinically relevant as prostate tumor development in this model is similar to that in humans in regard to progression from PIN lesions to adenocarcinoma. From the Hi-Myc model, we have generated two additional genetic modifications within prostate epithelial cells: 1) Hi-Myc mice with prostate-specific RON overexpression (OE) and 2) Hi-Myc mice with prostate-specific RON loss (ΔEpi). In this study we report that a lack of prostate RON expression diminishes adenocarcinoma development and metastasis within the Hi-Myc mouse model. Moreover, RON overexpression promotes the development of metastatic adenocarcinoma that was not observed in the prostates from Hi-Myc control mice. These studies suggest that RON expression supports the advancement of primary tumors to metastatic prostate cancer within the Hi-Myc mouse models. Therefore, future directions include determining the signaling pathways driven by RON that promotes this metastatic phenotype in both castration-sensitive and resistant tumors. Citation Format: Angelle D. Jones, Carissa Lester, Susan E. Waltz. RON receptor signaling enhances prostate cancer metastasis in Hi-Myc mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1243.

Abstract 3083: Targeting androgen receptor coregulators to enhance enzalutamide sensitivity in prostate cancer

Abstract Steroid hormone signaling axes drive proliferation and survival in prostate cancer (PCa), breast and other cancers. In late stage PCa, the androgen receptor (AR) is therapeutically antagonized with success, for example with Enzalutamide (Enza). Although initially successful, resistance emerges associated with tissue plasticity and patient mortality. Enza-resistance mechanisms include altered AR coregulator interactions. Identifying which coregulators change Enza sensitivity is attractive as they may represent new drug targets but challenging given the multitude of coregulators expressed in PCa and the diverse roles they play in transcription and translation.To meet this challenge, we designed a bioinformatic workflow to identify under-investigated yet clinically-impactful coregulators. We tested coactivators (CoA, n~750), corepressors (CoR, n ~600), and mixed function coregulators (Mixed, n~600) associations with patient outcome in TCGA PCa cohorts; applied partial correlation analyses to reveal coregulators that impacted AR target genes; utilized DepMap essentiality scores to rank importance; and examined interactions in publicly available AR RIME data. The impact of the top ranked coregulators (n=18) on Enza sensitivity was examined using shRNA or siRNA approaches, and with inhibitor drugs in Enza-resistant PCa cell lines (LNCaP C42B, 22Rv1). Finally, coregulator expression was examined in single cell RNA-Seq from PCa 3D organoids derived from the PBCre4:Ptenf/f:Rb1f/f (DKO) and the PBCre4:Ptenf/f:Rb1f/f:Trp53f/f (TKO) PCa mouse model, which recapitulate the loss of Enza sensitivity and lineage plasticity. ShRNA targeting coregulators was undertaken in organoids. The bioinformatics workflow identified 18 coregulators, including CoA (e.g., WDR5, KAT7, BLM, SMARCC1), CoR (e.g., SETDB1, PSPC1), and Mixed (e.g., KDM5A, BPTF, TCEGR1) to screen for impact on Enza. KAT7 shRNA modulated Enza sensitivity, regulated expression of AR target genes, and synergized with a KAT7 inhibitor (WM3835) to enhance Enza sensitivity. Similarly, a BLM inhibitor (ML216) synergized with Enza. Interestingly, although WDR5 siRNA alone did not alter Enza responses, the combination of KAT7 shRNA and WDR5 siRNA significantly potentiated Enza responses. Similarly, SMARCC1 shRNA cooperated with siRNA to several targets (TBX3, BPTF, or SETDB1) to enhance Enza responses. Smarcc1 and Tbx3 were upregulated in Enza-resistant neuroendocrine PCa, and the recently identified Pou2f3 Enza-resistant phenotypes, and Bptf was upregulated in the Tff3 Enza-resistant phenotype. We have shRNA targeted Blm, Smarcc1, Tbx3, and Bptf in the DKO and TKO organoids and are measuring the impact of Enza responses. Overall, we have identified potentially novel AR coregulators that associate with the development of therapy resistance and shown that targeting these coregulators may augment Enza sensitivity in PCa. Citation Format: Rayzel C. Fernandes, Debasis Nayak, Damien A. Leach, Meenalakshmi Chinnam, Wilbert Zwart, David W. Goodrich, Moray J. Campbell, Charlotte L. Bevan. Targeting androgen receptor coregulators to enhance enzalutamide sensitivity in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3083.