Prostate Cancer Patients Research Articles

Abstract C023: P21-positive senescent stromal cells promote prostate cancer immune suppression and progression that can be reversed by senolytic therapy

Abstract Cellular senescence is historically viewed as a tumor-suppressive cell cycle arrest program to limit outgrowth of pre-malignant cells. However, emerging evidence suggests senescent cell persistence contributes to immune suppression and cancer progression. Using prostate cancer patient samples and murine models, we find that p16+ senescent cells accumulate throughout malignant progression and are associated with immune suppression and poor survival. p16 ablation in mice eliminated senescent epithelial cells and reversed immune suppression mediated by immature myeloid cells but not prostate tumorigenesis. Single cell sequencing revealed an additional population of senescent p21+ fibroblasts and myeloid cells. Targeting BCL-xL or PD-L1 induced during senescence could remove both p16+ epithelial and p21+ stromal senescent cells, reactivate T cell immunity, and block tumor initiation as well as progression in advanced prostate cancer models. Our findings demonstrate that targeting heterogenous senescent populations can not only prevent malignant transformation but also yield therapeutic benefits in advanced prostate cancers through activating anti-tumor immunity. Citation Format: Lin Zhou, Kelly D. DeMarco, Katherine C. Murphy, Zhenpeng Wu, Jinping Li, Junhui Li, Calvin Johnson, Zhong Jiang, Shi Bai, Tianyi Ye, Karl Simin, Lihua Julie Zhu, Jason R Pitarresi, Hong Wu, Marcus Ruscetti. P21-positive senescent stromal cells promote prostate cancer immune suppression and progression that can be reversed by senolytic therapy [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr C023.

Advanced single-cell and spatial analysis with high-multiplex characterization of circulating tumor cells and tumor tissue in prostate cancer: Unveiling resistance mechanisms with the CoDuCo in situ assay.

Metastatic prostate cancer is a highly heterogeneous and dynamic disease and practicable tools for patient stratification and resistance monitoring are urgently needed. Liquid biopsy analysis of circulating tumor cells (CTCs) and circulating tumor DNA are promising, however, comprehensive testing is essential due to diverse mechanisms of resistance. Previously, we demonstrated the utility of mRNA-based in situ padlock probe hybridization for characterizing CTCs. We have developed a novel combinatorial dual-color (CoDuCo) assay for in situ mRNA detection, with enhanced multiplexing capacity, enabling the simultaneous analysis of up to 15 distinct markers. This approach was applied to CTCs, corresponding tumor tissue, cancer cell lines, and peripheral blood mononuclear cells for single-cell and spatial gene expression analysis. Using supervised machine learning, we trained a random forest classifier to identify CTCs. Image analysis and visualization of results was performed using open-source Python libraries, CellProfiler, and TissUUmaps. Our study presents data from multiple prostate cancer patients, demonstrating the CoDuCo assay's ability to visualize diverse resistance mechanisms, such as neuroendocrine differentiation markers (SYP, CHGA, NCAM1) and AR-V7 expression. In addition, druggable targets and predictive markers (PSMA, DLL3, SLFN11) were detected in CTCs and formalin-fixed, paraffin-embedded tissue. The machine learning-based CTC classification achieved high performance, with a recall of 0.76 and a specificity of 0.99. The combination of high multiplex capacity and microscopy-based single-cell analysis is a unique and powerful feature of the CoDuCo in situ assay. This synergy enables the simultaneous identification and characterization of CTCs with epithelial, epithelial-mesenchymal, and neuroendocrine phenotypes, the detection of CTC clusters, the visualization of CTC heterogeneity, as well as the spatial investigation of tumor tissue. This assay holds significant potential as a tool for monitoring dynamic molecular changes associated with drug response and resistance in prostate cancer.

A PSMA-targeted Tri-specific Killer Engager enhances NK cell cytotoxicity against prostate cancer.

Natural killer (NK) cell tumor infiltration is associated with good prognosis in patients with metastatic castration-resistant prostate cancer (mCRPC). NK cells recognize and kill targets by a process called natural cytotoxicity. We hypothesized that promoting an antigen-specific synapse with co-activation may enhance NK cell function in mCRPC. We describe a Tri-specific Killer Engager (TriKE) construct that engages with the activating receptor CD16 on NK cells, prostate-specific membrane antigen (PSMA) on mCRPC cells, and has an interleukin (IL)-15 moiety that is essential for NK cell survival, proliferation, and priming. We show that the PSMA TriKE specifically binds to PSMA-expressing cells and significantly enhances expansion, degranulation and cytokine production of NK cells derived from healthy donors or prostate cancer patients. Bystander killing of PSMA-negative was also achieved with PSMA TriKE treatment when co-cultured with PSMA-positive cells, suggesting potential PSMA TriKE benefit in controlling tumor antigen escape. When tested under physiologic conditions recapitulating the mCRPC tumor microenvironment (TME), NK cells treated with PSMA TriKE and prolonged exposure to hypoxia or MDSCs maintained their potent function while IL-15 treated NK cells showed greatly impaired cytotoxicity. Finally, in vivo testing of PSMA TriKE showed improved tumor control and survival of mice as compared to IL-15 and untreated control groups. In conclusion, PSMA TriKE demonstrates potential as a new therapy for advanced prostate cancer by providing additional signals to NK cells to maximize their anti-tumor potential in prostate cancer, especially in the setting of a hostile TME.

Enhancing bone metastasis prediction in prostate cancer using quantitative mpMRI features, ISUP grade and PSA density: a machine learning approach.

Bone metastasis is a critical complication in prostate cancer, significantly impacting patient prognosis and quality of life. This study aims to enhance bone metastasis prediction using machine learning (ML) techniques by integrating dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) perfusion features, International Society of Urological Pathology (ISUP) grade, and prostate-specific antigen (PSA) density. A retrospective analysis was conducted on 122 patients with histopathologically confirmed prostate cancer who underwent multiparametric prostate magnetic resonance imaging (mpMRI). Quantitative mpMRI features, PSA density, and ISUP grades were extracted and normalized. The dataset was balanced using oversampling and divided into training (70%) and test (30%) sets. Various ML models were developed and evaluated using area under the curve (AUC) metrics. Bone metastases were present in 26 patients (21.3%) at diagnosis. IAUGC and MaxSlope showed a statistically significant association with bone metastasis (p = 0.035, p = 0.050 respectively). The optimal PSA density cut-off value of 0.24 yielded a sensitivity of 0.88, specificity of 0.60, and AUC of 0.77. Machine learning models were developed using the dataset created with IAUGC, MaxSlope, ISUP grade, and PSA density values. Among the ML models, XGBoost demonstrated superior performance with validation and test AUCs of 91.5% and 92.6%, respectively, along with high precision (93.3%) and recall (93.1%). Integrating quantitative mpMRI features, ISUP grade, and PSA density through machine learning algorithms, particularly XGBoost, significantly improves the accuracy of bone metastasis prediction in prostate cancer patients. This approach can potentially reduce the need for additional imaging modalities and associated radiation exposure.

High 11-ketotestosterone linked to shorter time to castration resistance in recurrent non-metastatic prostate cancer.

The contribution of 11-oxygenated androgens to the progression of lethal prostate cancer (PCa) remains unresolved. We hypothesized that evaluating circulating levels of 11-oxygenated androgens, such as the androgen receptor agonist 11-ketotestosterone (11KT), could serve as a potential predictor of the onset of castration resistant prostate cancer (CRPC). We used mass spectrometry to quantify 11-oxygenated androgens in post-operative plasma samples acquired from 145 patients who subsequently received androgen deprivation therapy (ADT) for biochemical recurrence (BCR) and achieved castrated testosterone (T) levels. Kaplan-Meier survival analyses and multivariable Cox models were used to investigate relationships between steroids and CRPC. Of 145 patients, 31 developed CRPC with a median time to CRPC of 57 months. 11-oxygenated androgens levels were unaffected by ADT, which stands in contrast to the observed changes in T and other steroids. 11KT was the most abundant androgen but was not linked to clinical features. Kaplan-Meier analysis revealed that 11KT levels above the median of 273 pg/mL were associated with a shorter time to CRPC (P = 0.03). In multivariable analyses, this was supported with an adjusted hazard ratio of 2.17 (95% confidence interval (CI) 0.99-4.71; P = 0.05). 11KT is a key component of the hormonal profile predictive of earlier onset of CRPC. Enhancing our understanding of the specific role of 11KT in the progression to CRPC could help optimize hormonal therapy for castration sensitive PCa and CRPC patients.

Abstract B019: Androgen receptor-regulated lncRNA PRCAT71 promotes AR signaling through the interaction with RBPs in prostate cancer

Abstract Prostate cancer (PCa) is the second leading cause of cancer death in American men. PCa patients usually receive androgen deprivation therapy but eventually, they will relapse and tumors become castration-resistant PCa (CRPC) without effective treatments, highlighting the urgent need to develop better therapeutics to target advanced PCa. The main mechanism identified leading to castration resistance is aberrant androgen receptor (AR) reactivation, including AR overexpression. Approximately 80% of CRPC patients have a marked increase in AR mRNA and protein expression. Emerging evidence suggests genomic and transcriptomic changes insufficiently predict biology and mRNA and protein expression levels frequently do not correlate. Posttranscriptional regulation of AR mRNA can lead to AR overexpression. RNA binding proteins (RBPs) and non-coding RNAs (ncRNAs), such as microRNAs, long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), can control gene expression via direct binding to mRNAs and regulating mRNA processing, modification, and translation. Here in this study, we identified a novel PCa-specific lncRNA, PRCAT71, which is higher expressed in prostate tumor tissues than in benign tissues. Silencing PRCAT71 suppressed the cancerous properties of PCa cells, and reduced AR mRNA and protein expression levels, leading to inhibited AR signaling. We further uncovered that PRCAT71 formed an RNA-RNA duplex with AR mRNA, which enhanced the stability of AR mRNA. RNA pulldown assay identified PRCAT71- interacted RBPs. Silencing PRCAT71 reduced the interaction between key RBPs and AR mRNA, which is related to PRCAT71 regulating AR mRNA stability. Interestingly, PRCAT71 is transcriptionally regulated by AR-driven enhancers, thus forming a positive regulatory loop between AR and PRCAT71 in PCa. The high expression of PRCAT71 and key RBPs in PCa tumors are positively correlated with PSA level, AR activity and indicate worse patient overall survival and metastasis-free survival. Our study revealed a novel regulatory mechanism by which lncRNA PRCAT71 enhances the interaction of key RBPs with AR mRNA, stabilizes AR mRNA and promotes AR expression and PCa progression. Targeting PRCAT71-RBPs is a promising approach to treating CRPC. Citation Format: Yongyong Yang, Ting-You Wang, Qianru Li, Adam B Weiner, Jiawen Lu, Yanan Ren, Qingxiang Guo, Chaehyun Yum, Qi Liu, Rui Wang, Zhe Ji, Tamara L Lotan, Edward M Schaeffer, Rendong Yang, Qi Cao. Androgen receptor-regulated lncRNA PRCAT71 promotes AR signaling through the interaction with RBPs in prostate cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RNAs as Drivers, Targets, and Therapeutics in Cancer; 2024 Nov 14-17; Bellevue, Washington. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(11_Suppl):Abstract nr B019.

The prognostic value of cystography-measured bladder capacity on very early continence rates after radical prostatectomy.

To assess the utility and reliability of cost-effective cystography-measured bladder capacity as a prognostic tool for predicting very early continence recovery following radical prostatectomy. Additionally, the study aims to discuss the clinical implications of the findings, including their potential impact on patient management, postoperative rehabilitation strategies, and the development of personalized care pathways for prostate cancer patients. In this prospective monocentric study, we analyzed 223 patients who underwent either robot assisted radical prostatectomy (RARP) or open radical prostatectomy (ORP) between January 2022 and January 2024. Postoperative cystography was routinely performed 5 days after robot-assisted radical prostatectomy and 7 days after open radical prostatectomy. Very early continence rates were determined using a standardized pad-test conducted on the first day following catheter removal. The bladder capacity during cystography was measured and documented for every patient. The correlation between the rate of continence recovery and the bladder capacity was then assessed. To determine other predictive factors for recovery of continence, several parameters were analyzed using multivariate logistic regression analysis, including age, prostate volume, nerve-sparing technique and surgical procedure. Urinary continence rates at day 1 after catheter removal were 73.5% for patients who underwent RARP and 72.6% for patients who underwent ORP. A strong prognostic value of cystography-measured bladder capacity on very early continence rates was reported (p < 0.001), with a cut-off value calculated to be 140 ml of bladder capacity. After adjusting for additional variables such as age, surgical procedure, prostate volume and nerve-sparing technique, multivariate linear model analysis still found a strong correlation between cystography-measured bladder capacity and very early continence rates (p < 0.001). The cystography-measured bladder capacity may be a good predictor of the recovery of post-prostatectomy urinary continence.

Abstract A007: Characterization of miR-141 and miR-145 expression in cancer stem cells of metastatic prostate cancer patients

Abstract Background: Prostate cancer (PCA) is the second most prevalent cancer globally and the fifth leading cause of cancer-related mortality. However, effective prognostic biomarkers for metastatic PCA remain lacking. Recent research highlights the role of microRNAs (miRNAs) in regulating cancer stem cells (CSCs) and influencing tumour progression across various cancers. Therefore, in this we investigated the effects of miR-141 and miR-145 expression on the metastatic PCA of CSCs and assessed their potential role as biomarkers for metastatic PCA prognosis. Methods: The expression levels of miR-141 and miR-145 were quantified using real-time qPCR. Flow cytometry was employed to assess the levels of prostate cancer stem cells (PCSCs) in tissue samples from patients with localized (non-metastatic) and metastatic PCA. Results: Our findings revealed a significant increase in miR-141 expression, accompanied by elevated levels of CD44^high/CD24^low and CD133^high, in metastatic PCA compared to localized PCA. Conversely, reduced miR-145 expression was associated with enhanced stemness characteristics, as indicated by increased CD44^high/CD24^low and CD133^high levels, in metastatic PCA compared to localized PCA. Additionally, prostate-specific antigen (PSA) and testosterone levels exhibited a significant rise (p&amp;lt;0.001), while apoptosis rates decreased in both localized and metastatic PCA compared to localized PCA. Conclusions: The collective findings of this study suggest that miR-141 and miR-145, in conjunction with CSC markers, hold promise as diagnostic and prognostic tools for PCA. They may also be valuable for detecting minimal residual disease and improving therapeutic strategies for managing metastatic PCA. Citation Format: Kamla Kant Shukla, Gautam Ram Choudhary. Characterization of miR-141 and miR-145 expression in cancer stem cells of metastatic prostate cancer patients [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RNAs as Drivers, Targets, and Therapeutics in Cancer; 2024 Nov 14-17; Bellevue, Washington. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(11_Suppl):Abstract nr A007.

Exosomal PSM-E inhibits macrophage M2 polarization to suppress prostate cancer metastasis through the RACK1 signaling axis.

It is well-established that understanding the mechanism of prostate cancer (PCa)-associated metastasis is paramount for improving its prognosis. Metastasis is known to involve the communication between tumor-associated macrophages (TAMs) and tumor cells. Exosomes are crucial in mediating this intercellular communication within the tumor microenvironment. Nonetheless, the role of exosomal proteins in PCa metastasis is not yet fully understood. Here, we investigated the mechanisms of prostate cancer-derived exosomal PSM-E on regulating macrophage M2 polarization to suppress tumor invasion and metastasis. PSM-E levels in exosomes were detected by transmission electron microscopy and Western blotting analysis. The diagnostic value of urine-derived exosomal PSM-E in PCa were evaluated by LC-MS/MS, correlation analysis, and ROC curves analysis. The mechanisms underlying the inhibitory effect of exosomal PSM-E on the M2 polarization of macrophages was investigated by co-IP, IHC staining, and PCa tumorigenesis model, etc. RESULTS: We revealed that exosomal PSM-E is upregulated in exosomes derived from the serum and urine of PCa patients. Clinically, an elevated exosomal PSM-E expression in urine is significantly correlated with an advanced pathological tumor stage and a high Gleason score. Our research also revealed that exosomal PSM-E inhibits prostate cancer cell proliferation, invasion, and metastasis by suppressing macrophage polarization in vitro and in vivo. Furthermore, we provided compelling evidence that exosomal PSM-E inhibits M2 polarization of macrophages by recruiting RACK1 and suppressing the FAK and ERK signaling pathways, consequently suppressing PCa invasion and metastasis. Furthermore, we found that the protease-associated domain of PSM-E and the fourth tryptophan-aspartate repeat of RACK1 are crucial for the interaction between PSM-E and RACK1. Notably, exosomes carrying PSM-E from PCa urine could potentially serve as a biomarker for PCa, and targeting exosomal PSM-E may represent a strategy for preventing tumor progression in this patient population.

Abstract B026: Identification of small RNAs that function as multi-target therapeutics and as tools for novel target discovery in prostate cancer

Abstract Introduction: A major contributor to prostate cancer (PCa) mortality is the development of resistance to single agents targeting androgen receptor (AR) signaling. We have developed an unbiased shRNA-based negative selection screen to identify small RNAs (shRNAs and siRNAs) that inhibit PCa cell growth and survival (toxic sRNAs). Computational analyses of the most toxic sRNAs identified revealed that each can simultaneously target multiple known AR-coregulatory mRNAs. AR-coregulators modulate AR transcriptional response and are essential to AR signaling. We have proposed that the identified toxic sRNAs inhibit androgen signaling through seed-mediated targeting of androgen regulatory gene networks, resulting in inhibition of cell growth and viability. The goal of the current studies was to begin to analyze the broad therapeutic potential of these toxic sRNAs for PCa. We focused on analyzing i) their potential to thwart cell growth and/or viability when delivered to preclinical models of PCa, and ii) the targetome of the toxic sRNAs as a mean to uncover novel AR-coregulators that represent a targetable axis within androgen signaling. Methods: i) cationic lipid nanoparticles (LNPs), that efficiently deliver the toxic siRNAs to PCa cell lines, were used to deliver toxic siRNAs to organoids grown from PCa patient derived xenografts (PDX) models. 3D image analysis using the Ominer® software package was used to determine organoid count and size, the numbers of nuclei per organoid, and the fraction of dead cells to discriminate between cytotoxic and cytostatic effects. ii) to identify novel AR-coregulators, toxic siRNA direct targets were identified by sequencing of transcripts captured by biotinylated toxic siRNAs. Directly bound targets, were subjected to pathway enrichment and network analysis followed by identification of hub genes (Cytoscape). The effect of individually silencing potential AR-coregulators on the expression of androgen responsive genes was analyzed using Nanostring. Results and Conclusions: i) The effect of the toxic siRNAs on growth and viability of the PCa PDX-derived organoids will be presented and discussed as compelling preliminary data for therapeutic testing in more complex pre-clinical models (PCa PDXs). ii) Based on bioinformatic and downstream analysis of the direct targets of two toxic siRNAs, we selected 12 potentially novel AR- coregulators, with varied known functions including chromatin modifiers, transcriptional regulators, etc. Silencing of several of these potential AR-coregulators significantly affect expression of numerous AR responsive genes. Future experiments will focus on analyzing their interaction and functional association with the AR (i.e. effect of AR binding to chromatin). In conclusion, we have developed an assay that allowed the identification of toxic sRNAs for PCa cells and demonstrated their potential as therapeutics and as a tool for discovery of potential novel targets for PCa. Citation Format: Joshua M Corbin, Hamilton Young, Stefan Wilhelm, Adam S Asch, Chao Xu, Maria J Ruiz Echevarria. Identification of small RNAs that function as multi-target therapeutics and as tools for novel target discovery in prostate cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RNAs as Drivers, Targets, and Therapeutics in Cancer; 2024 Nov 14-17; Bellevue, Washington. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(11_Suppl):Abstract nr B026.

Current role of focal therapy in prostate cancer.

Thanks to the improved accuracy of multiparametric Magnetic Resonance Imaging (mpMRI) to detect and localize the dominant index lesion on prostate cancer (PCa), the concept of minimally invasive focal treatments (FT) has gained popularity. Nevertheless, although high-quality evidence that FT has favorable functional outcomes, definitive proof of its oncological effectiveness compared to standard treatments remains underreported. This study aims to explore the efficacy, safety, oncologic and functional outcomes of different type of FT for PCa. A non-systematic literature review was conducted by searching on PubMed "prostate cancer" AND "focal treatment" OR "HIFU" OR "irreversible electroporation" OR "cryoablation" OR "focal laser ablation." Overall, 22 articles published in English literature from 2018 to 2023 describing FT techniques for PCa were included. Related to the field ablated, focal therapies include hemiablation (half gland), focal ablation (zonal-base) or targeted therapy (lesion-based). FT modalities can be categorized in thermal and non-thermal energy: thermal energy techniques include high-intensity focused ultrasound (HIFU), cryotherapy, radiofrequency ablation (RFA), and focal laser ablation (FLA). Focal brachytherapy, irreversible electroporation (IRE), and vascular-targeted photodynamic therapy (VTP) are classified as non-thermal ablation. Each focal ablative treatments could be promising alternative to conventional radical therapies to treat PCa in term of mid-term oncologic and functional outcomes, however, limited data are available in comparison with standardized radical treatments. HIFU and Cryo are the most studied techniques and seem to be superior to radical treatments in term of functional outcomes despite associated with higher recurrence and retreatment rate. Current evidences of oncologic and functional outcomes of FT are based mainly on retrospective, non-comparative and single center studies. Thus, none of the focal therapies available should be considered safe alternative to standardized treatments in routine practice and should be offered only for well selected PCa patients with low or at least favorable-intermediate risk disease, unfit for radical options.

Enhancing risk stratification models in localized prostate cancer by novel validated tissue biomarkers.

Localized prostate cancer (PCa) is a largely heterogeneous disease regarding its clinical behavior. Current risk stratification relies on clinicopathological parameters and distinguishing between indolent and aggressive cases remains challenging. To improve risk stratification, we aimed to identify new prognostic markers for PCa. We performed an in silico analysis on publicly available PCa transcriptome datasets. The top 20 prognostic genes were assessed in PCa tissue samples of our institutional cohort (n = 92) using the NanoString nCounter technology. The three most promising candidates were further assessed by immunohistochemistry (IHC) in an institutional (n = 121) and an independent validation cohort from the EMPACT consortium (n = 199). Cancer-specific survival (CSS) and progression-free survival (PFS) were used as endpoints. Our in silico analysis identified 113 prognostic genes. The prognostic values of seven of the top 20 genes were confirmed in our institutional radical prostatectomy (RPE) cohort. Low CENPO, P2RX5, ABCC5 as well as high ASF1B, NCAPH, UBE2C, and ZWINT gene expressions were associated with shorter CSS. IHC analysis confirmed the significant associations between NCAPH and UBE2C staining and worse CSS. In the external validation cohort, higher NCAPH and ZWINT protein expressions were associated with shorter PFS. The combination of the newly identified tissue protein markers improved standard risk stratification models, such as D'Amico, CAPRA, and Cambridge prognostic groups. We identified and validated high tissue levels of NCAPH, UBE2C, and ZWINT as novel prognostic risk factors in clinically localized PCa patients. The use of these markers can improve routinely used risk estimation models.

Abstract B062: Transcriptomic analysis of whole blood samples from prostate cancer patients: A comparative study of patients from geographically diverse populations

Abstract Introduction: Prostate cancer is the most frequently diagnosed cancer across 112 countries. Among American men, an estimated 299, 010 new cases and 35,250 deaths are projected for 2024. In this study, the transcriptomic profile of prostate cancer patients from geographically and ethnically diverse cohorts (USA-Caucasian, RSA-Black) were compared to identify gene expression patterns associated with prostate cancer. Methods: Whole blood samples were collected from PCa and controls. Controls had the same age-range as PCa with no clinical indication of prostatic disease and serum PSA levels below 1.5 ng/ml. RNA was isolated, sequencing was carried out on Novaseq 6000, and data analyzed using PartekFlow to identify differential gene expression patterns (RSA-PCa: 6, RSA-Control: 6, USA-PCa: 7, USA-Control: 11). qRT-PCR was undertaken on a cohort of 27 biomarkers (PROSTest) related to PCa in whole blood. Results: Differential expression analysis identified distinct patterns in USA and RSA groups. In the USA PCa cohort, 2,193 genes were differentially expressed compared to the controls with fold change (FC) &amp;gt;1, p-value (p) &amp;lt;0.05, while in the RSA PCa cohort, 1,627 genes were differentially expressed compared to the controls. Pathway analyses identified enrichment for immune responsive genes in the RSA cohorts. We identified that 26 of 27 Wren’s PROSTest genes detectable in both groups. RNAseq and normalized PCR gene expression were well- correlated (r=0.44, p=0.0012, n=30 pairs). Conclusion: Based on this RNAseq study, there may be geographic differences related to ethnicity in overall blood RNA gene expression. We specifically identified alterations in immune function gene expression between the USA and RSA. Importantly, PROSTest genes were detected in both populations and exhibited a significant correlation. Development of gene signatures for biomarker discovery should, however, consider specific ethnicities and geographical regions. Citation Format: Srinivas V Koduru, Mark Kidd, Ané Pieters, S E Nagel, Robert P Millar, Abdel B Halim. Transcriptomic analysis of whole blood samples from prostate cancer patients: A comparative study of patients from geographically diverse populations [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr B062.

Abstract A003: CD45 positive circulating tumor cells as a prognostic marker in prostate cancer

Abstract Prostate cancer is one of the most common types of cancer among male patients worldwide, making early diagnosis and effective treatment crucial for improving patient survival rates. In this regard, circulating tumor cells (CTCs) have garnered attention as an important biomarker for cancer staging and monitoring treatment response. In prostate cancer, CTCs are typically identified as keratin+/CD45- cells, with additional markers such as PSA or PSMA also being used. The conventional CTC identification way have dismissed CD45+/keratin+ double-positive cells as artifacts by nonspecific binding during the staining process. However, recent studies have reported the presence of CD45+/keratin+ CTCs in various types of cancers, highlighting metastatic potential and their ability to evade the immune system. These findings require re- examination of the role for the double positive CTCs. Therefore, this study aimed to identify the presence of CD45+ CTCs in prostate cancer and to assess their clinical significance. Blood samples were collected from 80 prostate cancer patients, followed by unbiased isolation of CTCs, which were stained using PSA, keratin, and CD45. The detected CTCs were categorized based on CD45 expression, and the clinical relevance of each group was validated using patient information. Through this study, we aimed to confirm whether the CD45+ CTCs can be a clinical indicator in prostate cancer. The results revealed that CD45+ CTCs accounted for 90% of all detected CTCs, likely due to their high immune evasion capabilities. Additionally, in 17% of the patients, only CD45+ CTCs were detected, indicating the potential to expand CTC detection even in patients where CTCs were previously undetected using conventional criteria. The number of CD45+ CTCs was significantly higher in patients with progressive disease compared to those with complete or partial response, showing greater statistical significance than analyses using CD45- CTCs. Furthermore, the number of PSA+ CTCs was closely linked to changes in plasma PSA levels, suggesting they could be used as a supporting marker to enhance the accuracy of current plasma PSA tests. These findings indicate that CD45+ CTCs in prostate cancer are not merely artifacts of nonspecific binding but are indeed meaningful cells closely related to cancer progression. This study suggests that CD45+ CTCs have the potential to be utilized as a prognostic biomarker in prostate cancer. By including CD45+ CTCs, which were previously overlooked in conventional CTC analysis methods, more sensitive and accurate cancer monitoring could be achieved. In-depth future studies on the clinical applicability of CD45+ CTCs could significantly contribute to predicting prognosis and developing personalized treatment strategies for prostate cancer patients. Citation Format: Hyeongjung Woo, Woon-Hae Kim, Hyun Young Shin, Hyerin Jung, Hyung Ho Lee, Minseok S. Kim, Jae Young Joung. CD45 positive circulating tumor cells as a prognostic marker in prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A003.

Abstract A009: Integrative multiomic analysis of extracellular vesicle transcriptomics profiling combined with cfDNA methylation reveals improved stratification of low-risk and high- risk prostate cancer patients in urine-based liquid biopsy

Abstract Introduction: Prostate cancer (PCa) ranks as the second most frequently diagnosed cancer and the sixth most prevalent cause of cancer-related mortality in men globally. In this study, we employ a multiomic approach that utilizes both urine cfDNA and extracellular vesicle (EV) RNA-derived analytes to improve the risk stratification of individuals with prostate cancer and compare this to multi-parametric MRI performance as well as risk calculators in the same cohort. Materials and Methods: Urine was collected from 95 individuals comprising 51 benign or low-risk (Grade Group (GG) &amp;lt;=1), 10 intermediate-risk (GG2) and 44 high-risk PCa patients (GG 3-5). EV-RNA and cfDNA were concurrently isolated from each urine specimen to exploit complementary information. We developed an EV-RNA sequencing platform targeting mRNAs and lncRNAs and targeted 50 million reads per sample; and cfDNA methylome profiling reached an equivalent sequencing depth. Expression of EV-RNA and splice variant Differential Transcript Usage (DTU) and cfDNA methylation patterns were analyzed using Bio-Techne’s multiomic platform. Machine learning-based feature selection algorithms identified biomarker signatures from each analyte. Receiver-operator characteristic curves (ROC) were generated utilizing leave-one-out cross-validation of naïve Bayes classifier models to compute the area under the curve (AUC). Individual signatures were integrated to create a multiomic classifier. Results: Differential gene expression (DEx) analysis identified 18 DEx genes between low and high-risk patients with both known and novel implications in PCa. Splice variant analysis unveiled 60 genes previously implicated in PCa with DTU. Over 18,000 differentially methylated bases were detected between high and low-risk PCa patients. Feature selection analysis identified the top ten features of EV-RNA expression, splice variants, and cfDNA methylation, resulting in an integrative multi-analyte signature. The multiomic signature demonstrated an AUC of 0.92, surpassing any individual analyte’s performance, as well as the performance achieved by PSA (AUC = 0.52) and MRI PI RADS(AUC=0.65). Conclusions: While biomarker signatures obtained from each analyte in this study resulted in effective stratification of PCa risk, the multiomic signature further improved the discriminatory power—underscoring the complementary nature of the signals. Thus, a multiomic biomarker discovery strategy leveraging cfDNA and EV cargo exhibits significant potential as a risk assessment tool for high-grade prostate cancer. This approach can facilitate more informed decision-making in the context of biopsy procedures. Citation Format: Sudipto K Chakrabortty, Dulaney Miller, Kyle Manning, Rikky Xing, Jeff Cole, Christopher Benway, Sinead Nguyen, Allan George, Yiyuan Yao, Elena M Cortizas, Christian Ray, Siva Gowrisankar, Seth Yu, Allan Pollack, Sandra M Gaston, Sanoj Punnen, Johan Skog. Integrative multiomic analysis of extracellular vesicle transcriptomics profiling combined with cfDNA methylation reveals improved stratification of low-risk and high- risk prostate cancer patients in urine-based liquid biopsy [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A009.

Abstract A006: Development of a circulating tumor cell-derived cancer organoid platform for drug screening against metastatic tumors and longitudinal monitoring of drug resistance

Abstract Metastatic disease remains the primary cause of cancer-related deaths, presenting a significant challenge in oncology drug development. Current drug screening efforts often rely on cell lines or primary tumor-derived models, which may not adequately mimic the behavior of metastatic tumors. To address this, we aimed to develop a system that more accurately reflects metastatic tumors for improved drug screening. We leveraged a specialized culture platform featuring patented coated plates and proprietary media developed by AcroCyte (Taiwan) to cultivate circulating tumor cells (CTCs) into cancer organoids without pre-selection or enrichment. Building on our previous work, where we successfully cultivated CTCs from fresh blood and cryopreserved peripheral blood mononuclear cells (PBMCs) from renal, colon, and lung cancer patients into cancer organoids, we have now demonstrated the ability to freeze these CTC- derived organoids and thaw them for new culture when needed. We also present new data extending this success to breast and prostate cancers. CTCs from five frozen PBMC samples from breast cancer patients and three from prostate cancer patients formed visible colonies, with positive immunostaining for EpCAM, cytokeratin, and CD44. The immune cells in the PBMC samples gradually died off within three weeks of culture, as confirmed by the absence of CD45- positive cells. Interestingly, CTC-derived organoids from breast and prostate cancers did not form the spheroids observed in renal, colon, and lung cancer models. Instead, they appeared as colonies or clusters of CTCs. After 6-8 weeks of active growth, these clusters exhibited a slower growth rate, although they remained viable in the proprietary culture system. We are actively evaluating various culture media supplements, tailored to breast and prostate cancers, to extend the active growth period of these CTC-derived organoids for longer durations. Importantly, these CTC-derived colonies retained drug sensitivity, demonstrating the system's potential for effective drug screening against metastatic tumors. Our platform now supports organoid development from renal, colon, lung, breast, and prostate cancers, and we are actively expanding to include all major solid tumors. Since this technology uses blood, which can be obtained non-invasively, it enables longitudinal monitoring of CTCs as a functional liquid biopsy. Additionally, frozen PBMCs can be used as a source material for CTCs, and the resulting organoids can be utilized for drug sensitivity testing. This platform could be instrumental in oncology drug development and holds promise for monitoring emerging drug resistance in clinical trials by analyzing PBMC samples collected before and after treatment, offering a functional liquid biopsy-based approach to aid in developing therapies targeting metastatic disease. Citation Format: Yi-chun Han, David Hsieh, Ruobo Zhang, Emily Miyashita-Lin, Shian-Jiun Shih. Development of a circulating tumor cell-derived cancer organoid platform for drug screening against metastatic tumors and longitudinal monitoring of drug resistance [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A006.

Has the Time Come to Switch From Extensive Lymph Node Dissection to Sentinel Lymph Node Biopsy in Prostate Cancer Patients Treated With Radical Laparoscopic Prostatectomy?

Abstract The efficacy of the available procedures currently recommended for staging and prognostic evaluation of prostate cancer patients treated with radical laparoscopic prostatectomy is discussed, taking into account the available evidence and potential implications in patient management.

AR (CAG)n Microsatellite and APEX1 c.444T&gt;G (p.Asp148Glu) Polymorphisms as Independent Prognostic Biomarkers in Prostate Cancer: Insights from an Argentinian Cohort

Background/Objectives: Prostate cancer (PCa) is the leading malignancy and the third most common cause of cancer-related death in Argentinian men. Predicting outcomes in localized PCa remains difficult due to tumor heterogeneity. In this study, we assessed the impact of AR (CAG)n and APEX1 c.444T&gt;G polymorphisms on biochemical relapse in Argentine patients with localized PCa. Methods: We genotyped blood samples from 123 PCa patients for AR (CAG)n and APEX1 p.Asp148Glu (c.444T&gt;G) polymorphisms. Associations with clinicopathological parameters and biochemical relapse-free survival (BRFS) were assessed. Results: AR (CAG)20–23 was associated with a family history of breast/ovarian cancer (p = 0.0469). The combination of AR (CAG)20–23 and APEX1 c.444TT/GG correlated with a 2.89 times higher risk of biochemical relapse (log-rank p = 0.006). Multivariable analysis confirmed AR and APEX1 polymorphisms as independent predictors of biochemical relapse (HR = 3.95, p = 0.002). In patients with PSA levels &lt;10 ng/mL, combined AR (CAG)20–23 and APEX1 c.444TT/GG genotypes were significantly associated with an increased risk of biochemical relapse (HR = 2.61, p = 0.044). Multivariable analysis confirmed the prognostic significance of these genotypes (HR = 3.44, p = 0.02). Conclusions: This study has identified AR (CAG)n and APEX1 c.444T&gt;G polymorphisms as independent predictors of PCa relapse in Argentinian patients, suggesting their potential use in improving prognostic models.

Liquid-Biopsy Glycan Score Biomarker Accurately Indicates and Stratifies Primary and Metastatic Prostate Cancers.

Prostate cancer (PCa) is the most commonly diagnosed cancer in males. Early PCa usually shows no clinical symptoms and its primary diagnosis is currently guided by liquid-biopsy testing of serum prostate-specific antigen (PSA). This testing suffers from high false-positive and false-negative rates. Identifying new biomarkers for precise liquid-biopsy detection of PCa is, thus, an acute clinical request. Here, by using an advanced dual-functional aptamer assay, we quantified the extent of glycosylation of PSA circulating in cancer patients' serum, linked it to cancer-related breakage of PSA complexes with serum-circulating proteins, and proved its facility for stratification of primary and metastatic PCa. PSA's "Glycan Score" 100% accurately informed about PCa status in a 30-patient cohort, while serum PSA's concentration correctly classified only 53% of PCa patients and did not inform about their PCa status. The Glycan Score liquid-biopsy test thus has a huge potential for accurate diagnosis and staging of PCa, enabling mass-screening program progress and advanced PCa treatment monitoring.

Effectiveness of supervised combined aerobic and resistance exercise in fatigue of prostate cancer survivors under androgen deprivation therapy: a systematic review and meta-analysis

Abstract Objectives Cancer-related fatigue is prevalent in prostate cancer patients. This symptom can negatively affect patients’ performance and emotional well-being, but there is no consensus on the best therapeutic approach. Despite the growing evidence on the management of fatigue with exercise, there are recognised limitations in its use when considering the different cancer patients. Specifically, prostate cancer patients under androgen deprivation therapy present several contributors to fatigue, emotional distress, inactivity, and deconditioning. The aim of this research was to describe the current literature on the effects of supervised combined aerobic and resistance training on fatigue in patients under androgen deprivation therapy. Methods We conducted a literature search in PubMed, Scopus, and Web of Science. The GRADE and the Cochrane tools were used to assess the quality and risk of bias of the selected studies. Only randomised controlled trials in which combined aerobic and resistance training was used with prostate cancer patients under androgen deprivation therapy were included. A cancer-related fatigue meta-analysis was performed. Results Nine studies with a low risk of bias were included in the review. Regarding cancer-related fatigue, significant results that cannot be attributed to chance were found in favour of combined exercise (MD=0.71; 95 %; CI=0.05, 1.37; p=0.03; I2=91 %). The GRADE system showed a moderate recommendation. Conclusions Supervised combined aerobic and resistance training was proven to significantly improve fatigue in patients with prostate cancer under androgen deprivation therapy. These findings could provide clinicians with more information on the management of cancer patients under androgen deprivation therapy.