Cancer progression involves loss of differentiation and acquisition of stem cell-like traits, broadly referred to as "stemness". Here, we test whether the level of stemness, assessed by a transcriptome-derived Stemness score, can quantitatively track prostate cancer (PCa) development, progression, therapy resistance, metastasis, plasticity, and patient survival. Integrative analysis of transcriptomic data from 87,183 samples across 26 datasets reveals a progressive increase in Stemness and decline in pro-differentiation androgen receptor activity (AR-A) along the PCa continuum, with metastatic castration-resistant PCa (mCRPC) exhibiting the highest Stemness and lowest AR-A. Both the general Stemness score and a newly developed 12-gene "PCa-Stem Signature" correlate with and predict poor clinical outcomes. Mechanistically, increased AR-A may promote Stemness in early-stage PCa while MYC amplification and bi-allelic RB1 loss likely drive greatly elevated Stemness in mCRPC where AR-A is suppressed. Our findings establish Stemness as a robust quantitative measure of PCa aggressiveness and offer a scalable framework for PCa risk stratification.

In the phase 3 IPATential150 trial, ipatasertib addition to abiraterone significantly reduced the risk of disease progression in men with metastatic castration-resistant prostate cancer (mCRPC) with PTEN loss on immunohistochemistry (IHC), but not in the intention-to-treat (ITT) population. Here we report the final overall survival (OS) analysis and present results for prespecified and exploratory biomarker analyses.

Patients were randomized to receive ipatasertib (400 mg once daily) or placebo. All patients received abiraterone (1000 mg once daily) and prednisone (5 mg twice daily). OS was assessed in patients with PTEN loss on IHC and the ITT population. Exploratory biomarker analyses included PTEN status via next-generation sequencing (NGS) and other key genomic alterations.

At final analysis (median follow-up 33.9 mo), ipatasertib addition did not improve OS for patients with PTEN loss in IHC (n = 521; stratified hazard ratio [sHR] 0.94, 95% confidence interval [CI] 0.76-1.17; p = 0.57) or the ITT population (n = 1101; sHR 0.91, 95% CI 0.79-1.07; not formally tested). Exploratory NGS assessments identified subgroups with genomic PTEN loss (n = 208) or PIK3CA/AKT1/PTEN alterations (n = 250), with potentially better outcomes from ipatasertib (HR 0.76, 95% CI 0.54-1.07; and HR 0.70, 95% CI 0.51-0.96, respectively). Limitations include the exploratory nature of the analysis, incomplete availability of NGS data, and potential intrapatient heterogeneity.

Ipatasertib addition to abiraterone did not improve OS for men with mCRPC, regardless of PTEN status on IHC. Exploratory biomarker analyses identified additional genomic alterations of potential clinical relevance for AKT blockade in mCRPC that require further validation in prospective studies.

Genome-wide screens using CRISPR/RNAi can identify new therapeutic vulnerabilities in prostate cancer. In this study, we combine DepMap functional screen data with a large gene expression database (N = 1012) and clinical outcomes to identify potentially druggable targets. Eight genes (CYC, CYP51A1, DHFR, EBP, KIF15, PPM1D, SQLE, and UMPS) demonstrated strong dependency in cell lines and were also associated with worse prognosis clinically, representing potential therapeutic targets in metastatic prostate cancer. Four of these (DHFR, EBP, KIF15, and PPM1D) demonstrated higher expression in neuroendocrine prostate cancer. Furthermore, all but one (KIF15) were not significantly decreased from pretreatment to posttreatment, suggesting that they may remain targetable postabiraterone therapy. All eight genes showed evidence of protein expression in prostate cancers or cell lines. These potentially druggable targets associated with prostate cancer cell line dependency and worse clinical outcomes have also demonstrated literature support as potential targets, supporting further research into their potential clinical relevance as therapeutic targets in prostate cancer.

Androgen receptor (AR), a member of the nuclear receptor superfamily controls prostate epithelial cell plasticity by repressing a panel of genes involved in epithelial-mesenchymal transition (EMT), including the human CDH2 gene encoding N-cadherin. At the opposite, pathological AR variants such as AR-V7 associated with prostate tumor progression upregulate those EMT genes. Here, focusing on the human CDH2 gene, we show that this duality between AR and AR-V7 relies on a potential human accelerated region present in the intron 1. This fastest-evolving region of the human genome is actually a variable number tandem repeat (VNTR) comprising 24 repetitions of a DNA sequence that englobes binding sites for steroid hormone receptors, recombination signal binding protein for immunoglobulin kappa j region (RBPJ) an effector of the Notch pathway, and zinc finger e-box binding homeobox 1 (ZEB1). Genomic DNA sequencing, multiple sequence alignment, data mining, as well as protein-DNA interaction and gene expression analyses indicate that this VNTR constitutes a potential transcriptional hub for different transcription factors to control human CDH2 expression. Also, our data suggest that prostate tumor cells may unlock an up to now unknown molecular mechanism associated with a fine-tuned control of human CDH2 gene expression.

Prostate cancer (PCa) stands as a leading cause of cancer-related mortality among men, with treatment-induced neuroendocrine prostate cancer (NEPC) posing a challenge as an ARPI-resistant subtype. The role of transcription factors (TFs) in PCa progression and NEPC transdifferentiation remains inadequately understood, underscoring a critical gap in current research. In this study, an internal Z score-based approach is developed to identify lineage-specific TF profiles in prostatic adenocarcinoma and NEPC for a nuanced understanding of TF expression dynamics. Distinct TF profiles for adenocarcinoma and NEPC are unveiled, identifying 126 shared TFs, 46 adenocarcinoma-TFs, and 56 NEPC-TFs, validated across multiple cohorts. Gene Ontology is employed to validate their biological and functional roles in PCa progression. Implications are revealed in cell development, differentiation, and lineage determination. Knockdown experiments suggest that lineage-TFs are functionally important in maintaining lineage-specific cell proliferation. Additionally, a longitudinal study on NE transdifferentiation highlights dynamic TF expression shifts, proposing a three-phases hypothesis for PCa progression mechanisms. This study introduces a groundbreaking approach for deciphering the TF landscape in PCa, providing a molecular basis for adenocarcinoma to NEPC progression, and paving the way for innovative treatment strategies with potential impact on patient outcomes.

Neuroendocrine prostate cancer (NEPC) is rare at the time of initial diagnosis but much more common in patients treated with the combination of androgen deprivation therapy (ADT) and androgen receptor pathway inhibitors (ARPI) such as abiraterone and enzalutamide. NEPC is typically characterized by the loss of prostate-specific membrane antigen (PSMA) expression while exhibiting variable neuroendocrine markers. Recent advancements in nuclear medicine have provided a promising avenue for the development of molecular imaging techniques and targeted therapies tailored to NEPC. This review examines the current and future role of theranostics in the diagnosis and management of NEPC and explores potential future directions in this rapidly evolving field.

Anti-androgen resistance remains a major clinical challenge in the treatment of prostate cancer (PCa), leading to disease progression and treatment failure. Despite extensive research on resistance mechanisms, a reliable prognostic model for predicting patient outcomes and guiding therapeutic strategies is still lacking. This study aimed to develop a novel gene signature related to anti-androgen resistance and evaluate its prognostic and therapeutic implications.

Anti-androgen resistance-related differentially expressed genes (ARRDEGs) were identified through transcriptomic analysis of enzalutamide- and dual enzalutamide abiraterone-resistant PCa cell lines from the GEO database. Functional enrichment analysis was performed to determine the biological roles of these genes. A prognostic gene signature was developed using univariate Cox regression, LASSO, and multivariate Cox regression models. The model was validated in independent PCa cohorts from The Cancer Genome Atlas (TCGA). Additionally, we assessed the correlation between the signature, immune infiltration, immune checkpoint expression, and drug sensitivity. The efficacy of PLK1 inhibition combined with enzalutamide was further explored using in vitro and in vivo experiments.

We identified 304 ARRDEGs, from which three key genes (LMNB1, SSPO, and PLK1) were selected to construct a prognostic signature. This gene signature effectively stratified PCa patients into high- and low-risk groups, with the high-risk group exhibiting shorter recurrence-free survival and distinct immune characteristics. High-risk patients demonstrated elevated immune checkpoint expression (B7H3, CTLA-4, B7-1, and TIGIT), increased M2 macrophage infiltration, and enhanced sensitivity to chemotherapy and targeted therapy. Mechanistically, PLK1 inhibition potentiated the antitumor effect of enzalutamide by downregulating SLC7A11 and inducing ferroptosis, providing a potential therapeutic strategy to overcome anti-androgen resistance.

We established a novel ARRDEGs-based prognostic signature that predicts PCa progression and response to chemotherapy and targeted therapy. The integration of this signature with immune profiling and drug sensitivity analysis provides a valuable tool for precision oncology in PCa. Our findings highlight the potential of PLK1 inhibition as a therapeutic strategy to enhance enzalutamide efficacy and overcome resistance.

Double-negative prostate cancer (DNPC), characterized by an androgen receptor (AR)- and neuroendocrine-null phenotype, frequently emerges following androgen deprivation therapy (ADT). However, our understanding of the origins and regulatory mechanisms of DNPC remains limited. Here, we discover that tumors with KMT2C mutation or loss are highly susceptible to transitioning into DNPC following ADT. We clarify that DNPC primarily stems from luminal cell transdifferentiation rather than basal cell transformation. Antiandrogen treatment induces KMT2C binding at enhancers of a subset of AR-regulated genes, preserving the adenocarcinoma lineage. KMT2C maintains ASPP2 expression via enhancer-promoter communication post-AR inhibition, while its inactivation reduces ASPP2, triggering ΔNp63-dependent transdifferentiation. This DNPC transition maintains fatty acid (FA) synthesis through ΔNp63-mediated SREBP1c transactivation, fueling DNPC growth via HRAS palmitoylation and MAPK signaling activation. These findings highlight KMT2C as an epigenetic checkpoint against DNPC development and suggest the therapeutic potential of targeting fatty acid synthesis.

Neuroendocrine prostate cancer (NEPC), a subtype of prostate cancer (PCa) with poor prognosis and high heterogeneity, currently lacks accurate markers. This study aims to identify a robust NEPC classifier and provide new perspectives for resolving intra- tumoral heterogeneity. Multi-omics analysis included 19 bulk transcriptomics, 14 single-cell transcriptomics, 1 spatial transcriptomics, 16 published NE signatures and 10 cellular experiments combined with multiple machine learning algorithms to construct a novel NEPC classifier and classification. A comprehensive single-cell atlas of prostate cancer was created from 70 samples, comprising 196,309 cells, among which 9% were identified as NE cells. Within this framework and in combination with bulk transcriptomics, a total of 100 high-quality NE-specific feature genes were identified and differentiated into NEPup sig and NEPdown sig. The random forest (RF) algorithm proved to be the most effective classifier for NEPC, leading to the establishment of the NEP100 model, which demonstrated robust validation across various datasets. In clinical settings, the use of the NEP100 model can greatly improve the diagnostic and prognostic prediction of NEPC. Hierarchical clustering based on NEP100 revealed four distinct NEPC subtypes, designated VR_O, Prol_N, Prol_P, and EMT_Y, each of which presented unique biological characteristics. This allows us to select different targeted therapeutic strategies for different subtypes of phenotypic pathways. Notably, NEP100 expression correlated positively with neuroendocrine differentiation and disease progression, while the VR-NE phenotype dominated by VR_O cells indicated a propensity for treatment resistance. Furthermore, AMIGO2, a component of the NEP100 signature, was associated with chemotherapy resistance and a poor prognosis, indicating that it is a pivotal target for future therapeutic strategies. This study used multi-omics analysis combined with machine learning to construct a novel NEPC classifier and classification system. NEP100 provides a clinically actionable framework for NEPC diagnosis and subtyping.

Castration-resistant prostate cancer frequently metastasizes to the liver, and prostate cancer liver metastases often present a neuroendocrine phenotype (i.e., neuroendocrine prostate cancer [NEPC]), but the underlying molecular underpinnings remain unclear. In this issue of the JCI, Liu et al. demonstrate that the neurotransmitter serotonin (also known as 5-hydroxytryptamine), produced by NEPC cells, gained access to and activated neutrophils by modifying histone 3 (H3) to form neutrophil extracellular traps, which in turn promoted NEPC macrometastases in the liver. The study suggests that blocking serotonin transport to neutrophils and inhibiting the enzymes that catalyze serotonin-mediated H3 modifications may represent alternative approaches to treating prostate cancer liver metastases.

Enzalutamide (Enz) is employed in the management of castration-resistant prostate cancer (CRPC). However, a substantial subset of patients may develop resistance to Enz, thereby reducing its therapeutic effectiveness. The underlying mechanisms contributing to the development of Enz resistance in PCa, whether arising from androgen deprivation or the burden of Enz treatment, remain inadequately understood. OPRK1 plays a key role in Enz resistance through ferroptosis inhibition, which is detected by the analysis of Gene Expression Omnibus (GEO) databases. Silencing OPRK1 via small interfering RNA (siRNA) resulted in the activation of ferroptosis signaling in LNCaP cells. These findings indicate that OPRK1 significantly contributes to Enz resistance in PCa and may serve as a promising therapeutic target for resistant patients.

Prostate cancer (PCa) is the second most common malignant tumor in men worldwide, particularly castration-resistant prostate cancer (CRPC), for which enzalutamide (Enz) resistance is of particular concern. Modifications to histone methylation and acetylation patterns are closely associated with resistance to Enz in these patients. As PCa progresses, cancer cells alter their histone modification patterns, leading to a reduction in Enz treatment efficacy. Signaling pathways in the tumor microenvironment regulate gene expression by affecting the activity of histone-modifying enzymes, further affecting the efficacy of Enz. This review summarizes recent research about changes in histone modification patterns that occur in drug resistance-related genes at different stages of PCa and explores the potential use of combination therapies for reversing this process, providing insights into novel treatment strategies to improve the clinical efficacy of Enz.

New biomarkers for the detection and monitoring of aggressive variant prostate cancer (AVPC) including therapy-induced neuroendocrine prostate cancer (NEPC) are urgently needed, as measuring prostate-specific antigen (PSA) is not reliable in androgen-indifferent diseases. Molecular analysis of circulating tumor cells (CTC) enables repeated analysis for monitoring and allows to capture the heterogeneity of the disease.

102 blood samples from 76 metastatic prostate cancer (mPC) patients, including 37 samples from histologically proven NEPC, were collected and CTCs were enriched using label-dependent and label-independent methods. Relevant transcripts were selected for CTC profiling using semi-quantitative RT-PCR analysis and validated in published datasets and cell lines. Transcriptional profiles in patient samples were analyzed using supervised and unsupervised methods.

CTC counts were increased in AVPC and NEPC as compared to metastatic hormone-sensitive prostate cancer (mHSPC). Gene expression profiles of CTCs showed a high degree of inter-patient heterogeneity, but NEPC-specific transcripts were significantly increased in patients with proven NEPC, while adenocarcinoma markers were decreased. Unsupervised analysis identified four distinct clusters of CTClow, ARhigh, amphicrine and pure NEPC gene expression profiles that reflected the clinical groups. Based on the transcript panel, NEPC could be distinguished from mHSPC or AVPC patients with a specificity of 95.5% and 88.2%, respectively.

Molecular subtypes of mPC can be distinguished by transcriptional profiling of CTCs. In the future, our convenient PCR-based analysis may complement the monitoring of advanced PCa patients and allow timely detection of resistance to androgen receptor pathway inhibitors.

The transdifferentiation from adenocarcinoma to neuroendocrine prostate cancer (NEPC) in men confers antiandrogen therapy resistance. Here our analysis combining CRISPR‒Cas9 screening with single-cell RNA sequencing tracking of tumor transition demonstrated that antiandrogen-induced zinc finger MYND-type containing 8 (ZMYND8)-dependent epigenetic programming orchestrates NEPC transdifferentiation. Ablation of Zmynd8 prevents NEPC development, while ZMYND8 upregulation mediated by achaete-scute homolog 1 promotes NEPC differentiation. We show that forkhead box protein M1 (FOXM1) stabilizes ZMYND8 binding to chromatin regions characterized by H3K4me1-H3K14ac modification and FOXM1 targeting. Antiandrogen therapy releases the SWI/SNF chromatin remodeling complex from the androgen receptor, facilitating its interaction with ZMYND8-FOXM1 to upregulate critical neuroendocrine lineage regulators. We develop iZMYND8-34, a small molecule designed to inhibit ZMYND8's histone recognition, which effectively blocks NEPC development. These findings reveal the critical role of ZMYND8-dependent epigenetic programming induced by androgen deprivation therapy in orchestrating lineage fate. Targeting ZMYND8 emerges as a promising strategy for impeding NEPC development.

Aggressive variant and androgen receptor (AR)-independent castration resistant prostate cancers (CRPC) represent the most significant diagnostic and therapeutic challenges in prostate cancer. This study examined a case of simultaneous progression of both adenocarcinoma and squamous tumors from the same common origin. Using whole-genome and transcriptome sequencing from 17 samples collected over >6 years, we established the clonal relationship of all samples, defined shared complex structural variants, and demonstrated both divergent and convergent evolution at AR. Squamous CRPC-associated circulating tumor DNA was identified at clinical progression prior to biopsy detection of any squamous differentiation. Dynamic changes in the detection rate of histology-specific clones in circulation reflected histology-specific sensitivity to treatment. This dataset serves as an illustration of non-neuroendocrine transdifferentiation and highlights the importance of serial sampling at progression in CRPC for the detection of emergent non-adenocarcinoma histologies with implications for the treatment of lineage plasticity and transdifferentiation in metastatic CRPC.

Neuroendocrine prostate cancer (NEPC), an aggressive subtype induced by hormone therapy, lacks effective treatments. This study explored the role of E26 transformation-specific variant 5 (ETV5) in NEPC development. Analysis of multiple prostate cancer datasets revealed that NEPC is characterized by significantly elevated ETV5 expression compared to other subtypes. ETV5 expression increased progressively under hormone therapy through epigenetic modifications. ETV5 induced neural stem-like features in prostate cancer cells and facilitated their differentiation into NEPC under hormone treatment conditions, both in vitro and in vivo. Our molecular mechanistic study identified PBX3 and TLL1 as target genes of ETV5 that contribute to ETV5 overexpression-induced castration resistance and stemness. Notably, obeticholic acid, identified as an ETV5 inhibitor in this study, exhibited promising efficacy in suppressing NEPC development. This study highlights ETV5 as a key transcription factor that facilitates NEPC development and underscores its potential as a therapeutic target for this aggressive cancer subtype.

Neuroendocrine prostate cancer (NEPC) arises primarily through neuroendocrine transdifferentiation (NEtD) as an adaptive mechanism of therapeutic resistance. Models to define the functional effects of putative drivers of this process on androgen receptor (AR) signaling and NE cancer lineage programs are lacking. We adapted a genetically defined strategy from the field of cellular reprogramming to directly convert AR-active prostate cancer (ARPC) to AR-independent NEPC using candidate factors. We delineated critical roles of the pioneer factors ASCL1 and NeuroD1 in NEtD and uncovered their abilities to silence AR expression and signaling by remodeling chromatin at the somatically acquired AR enhancer and global AR binding sites with enhancer activity. We also elucidated the dynamic temporal changes in the transcriptomic and epigenomic landscapes of cells undergoing acute lineage conversion from ARPC to NEPC which should inform future therapeutic development. Further, we distinguished the activities of ASCL1 and NeuroD1 from the inactivation of RE-1 silencing transcription factor (REST), a master suppressor of a major neuronal gene program, in establishing a NEPC lineage state and in modulating the expression of genes associated with major histocompatibility complex class I (MHC I) antigen processing and presentation. These findings provide important, clinically relevant insights into the biological processes driving NEtD of prostate cancer.

Aggressive variants of prostate cancer (AVPC) comprise a heterogeneous group of prostate carcinomas characterized by androgen-independent, aggressive tumor growth. Clinically, they are characterized by prostate-specific antigen (PSA)-negative progression and an atypical metastatic pattern with increased visceral and osteolytic metastasis. Based on immunohistochemistry and transcriptome profiling, AVPC are divided into four subgroups: neuroendocrine prostate cancer (NEPC), amphicrine prostate cancer, androgen receptor-low expressing prostate cancer and double-negative prostate cancer. However, differentiating between the subgroups can be challenging. For the transformation process of an adenocarcinoma into an AVPC, so-called transdifferentiation, the inactivation of the tumor suppressor genes RB1, PTEN and TP53 plays a crucial role. Epigenetic changes contribute to the development of stem cell-like properties. AVPC is mostly treated with platinum-based chemotherapy, depending on the subtype in combination with etoposide or a taxane. New therapeutic approaches are investigating the use of chemotherapy combinations with PARP inhibitors, checkpoint inhibitors or immunomodulators. In addition, T‑cell engagers have achieved initial promising results, particularly in NEPC. Treatment of AVPC patients in trials is desirable to improve evidence for this aggressive form of prostate cancer.

Prostate cancer (PC) growth is hormone-dependent and it frequently develops distant metastases as disease progresses. Patients with metastatic castration-sensitive prostate cancer (mCSPC) initially respond to androgen deprivation therapy (ADT) but eventually become refractory and develop metastatic castration-resistant prostate cancer (mCRPC). Castration-resistance is associated with high lethality and metastases confer poor prognosis, therefore unmet needs in treatment for mCSPC remain high. So far, improvements in survival in mCSPC have been achieved by doublet combination therapy such as docetaxel or an androgen-receptor signaling inhibitor (ARSI) in addition to ADT. Further, recent phase 3 trials have shown that triplet therapy-a combination of ARSI, docetaxel, and ADT improves prognosis compared with docetaxel plus ADT in mCSPC. PC tumors manifest intra- and inter-tumoral heterogeneity at both the genetic and phenotypic level. As heterogeneity increases during sequential treatment and disease progression, it is reasonable to initiate combination therapy using drugs with different mechanisms of action early in the course of disease, such as mCSPC. Previous research about tumor heterogeneity and drug resistant mechanism support this rationale, as well as preclinical studies and real-world data provide the scientific evidence of benefit by combining ARSI and docetaxel. Here, we review the rationale and clinical evidence for triplet therapy in patients with mCSPC.

Despite improvements in diagnosis and treatment approaches, prostate cancer (PC) remains a leading cause of cancer-related death in men. PC progresses through various stages, mostly driven by androgen receptor signaling. However, after androgen deprivation therapies, in a significant portion of patients, several different molecular mechanisms contribute to the development of castration resistance. Delving deeply into the molecular landscape of castration-resistant PC, grasping the selective pressures exerted by therapies, and understanding the drivers of lineage plasticity is pivotal to prevent progression. Targeting genetic and epigenetic alterations that drive this transition will guide clinical management strategies and possibly prevent and/or treat lethal disease.

Metastatic castration-resistant prostate cancer (mCRPC) is a heterogeneous disease. Several studies have identified transcriptional subtypes of mCRPC, but comprehensive analysis of prognostic gene expression pathways has been limited. Therefore, we aggregated a cohort of 1012 mCRPC tissue samples from 769 patients and investigated the association of gene expression-based pathways with clinical outcomes and intrapatient and intratumor heterogeneity. Survival data were obtained for 272 patients. Pathway-level enrichment was evaluated using gene set variation analysis. scRNA-seq datasets from mCRPC tissue biopsies and circulating tumor cells were used to investigate heterogeneity of adverse pathways. We identified five pathway clusters: (a) Immune response/WNT/TGF-beta signaling, (b) AR signaling/luminal signatures, (c) mTOR signaling and glycolysis, (d) cell proliferation, and (e) neuroendocrine differentiation. Proliferation, AR signaling loss, and glycolysis/mTOR signaling were independently prognostic. Adverse prognostic pathway scores decreased on treatment with AR signaling inhibitors, but not at progression, suggesting failure to permanently target these pathways. scRNA-seq datasets from mCRPC tissue biopsies and circulating tumor cells were used to investigate heterogeneity of adverse pathways. Our results suggest loss of AR signaling, high proliferation, and a glycolytic phenotype as adverse prognostic pathways in mCRPC that could be used in conjunction with clinical factors to prognosticate for treatment decisions.

Prostate cancer (PCa) is one of the most common malignancies in men worldwide. Despite advances in treatment, many patients develop resistance to conventional therapies. Solute carrier (SLC) proteins, as transmembrane transporters, have recently emerged as potential therapeutic targets due to their role in tumor metabolism and progression. This review summarizes the key roles of six SLC proteins in PCa, including their involvement in metabolic reprogramming, regulation of signaling pathways, and effects on the tumor microenvironment. Although targeting of SLC family members in prostate cancer remains an underexplored area, the growing body of evidence suggests that it holds potential for future development.

Cell phenotype underlies prostate cancer presentation and treatment resistance and can be regulated by epigenomic features. However, the osteotropic tendency of prostate cancer limits access to metastatic tissue, meaning most prior insights into prostate cancer chromatin biology are from preclinical models that do not fully represent disease complexity. Noninvasive chromatin immunoprecipitation of histones in plasma cell-free DNA (cfDNA) in humans may enable the capture of disparate prostate cancer phenotypes. In this study, we analyzed activating promoter- and enhancer-associated H3K4me2 from cfDNA in metastatic prostate cancer enriched for divergent patterns of metastasis and diverse clinical presentation. H3K4me2 density across prostate cancer genes, accessible chromatin, and lineage-defining transcription factor-binding sites correlated strongly with ctDNA fraction-demonstrating capture of prostate cancer-specific biology and informing the development of a statistical framework to adjust for ctDNA fraction. Chromatin hallmarks mirrored synchronously measured clinicogenomic features: bone- versus liver-predominant disease, serum PSA, biopsy-confirmed histopathologic subtype, and RB1 deletions convergently indicated phenotype segregation along an axis of differential androgen receptor activity and neuroendocrine identity. Detection of lineage switching after sequential progression on systemic therapy in select patients indicates potential use for individualized resistance monitoring. Epigenomic footprints of metastasis-induced normal tissue destruction were evident in bulk cfDNA from two patients. Finally, a public epigenomic resource was generated using a distinct chromatin marker that has not been widely investigated in prostate cancer. These results provide insights into the adaptive molecular landscape of aggressive prostate cancer and endorse plasma cfDNA chromatin profiling as a biomarker source and biological discovery tool. Significance: Plasma cell-free chromatin immunoprecipitation sequencing enables phenotypic dissection of lethal prostate cancer and is a practical tool for biomarker discovery while overcoming prior limitations of access to relevant tissue and reliance on model systems.

Inhibiting the androgen receptor (AR) is effective for treatment of advanced prostate cancers because of their AR-dependent luminal epithelial cell identity. Tumors progress during therapy to castration-resistant prostate cancer (CRPC) by restoring AR signaling and maintaining luminal identity or by converting through lineage plasticity to a neuroendocrine (NE) identity or double-negative CRPC (DNPC) lacking luminal or NE identities. Here, we show that DNPC cells express genes defining basal, club, and hillock epithelial cells from benign prostate. We identified KLF5 as a regulator of genes defining this mixed basal, club, and hillock cell identity in DNPC models. KLF5-mediated upregulation of RARG uncovered a DNPC sensitivity to growth inhibition by retinoic acid receptor agonists, which down-regulated KLF5 and up-regulated AR. These findings offer CRPC classifications based on prostate epithelial cell identities and nominate KLF5 and RARG as therapeutic targets for CRPC displaying a mixed basal, club, and hillock identity.

The use of supraphysiologic testosterone, particularly when alternated with an anti-androgen agent in men with metastatic castration-resistant prostate cancer (CRPC), has demonstrated promising results in clinical trials. As the use of this therapy in clinical practice is more widely adopted, there will be a growing need to understand the mechanisms of resistance. To that end, we independently derived three separate cell models of testosterone-sensitive CRPC. From each CRPC line, high dose testosterone-resistance (HTR) lines were selected. We demonstrated the differential response of the three CRPC lines to a high dose of testosterone in vitro and in vivo. We subsequently demonstrated the resistance of the HTR lines to testosterone and varying responses to testosterone withdrawal in vivo. The heterogeneity in responses to hormonal manipulation is correlated with varying levels of androgen receptor expression within the population. Overall, we show that we have developed three models of HTR that can be used to study the mechanisms of high dose testosterone resistance and identify potential therapeutic targets.

Lineage plasticity and histologic transformation from prostate adenocarcinoma to neuroendocrine (NE) prostate cancer (NEPC) occur in up to 15% to 20% of patients with castration-resistant prostate cancer (CRPC) as a mechanism of treatment resistance and are associated with aggressive disease and poor prognosis. NEPC tumors typically display small cell carcinoma morphology with loss of androgen receptor (AR) expression and gain of NE lineage markers. However, there is a spectrum of phenotypes that are observed during the lineage plasticity process, and the clinical significance of mixed histologies or those that co-express AR and NE markers or lack all markers is not well defined. Translational research studies investigating NEPC have used variable definitions, making clinical trial design challenging. In this manuscript, we discuss the diagnostic workup of metastatic biopsies to help guide the reproducible classification of phenotypic CRPC subtypes. We recommend classifying CRPC tumors based on histomorphology (adenocarcinoma, small cell carcinoma, poorly differentiated carcinoma, other morphologic variant, or mixed morphology) and IHC markers with a priority for AR, NK3 homeobox 1, insulinoma-associated protein 1, synaptophysin, and cell proliferation based on Ki-67 positivity, with additional markers to be considered based on the clinical context. Ultimately, a unified workup of metastatic CRPC biopsies can improve clinical trial design and eventually practice.

The 11th Annual 2024 Coffey - Holden Prostate Cancer Academy (CHPCA) Meeting, was themed "Personalized Medicine: Leave No Patient Behind," and was held from June 20 to 23, 2024 at the University of California, Los Angeles, Luskin Conference Center, in Los Angeles, CA.

The CHPCA Meeting is an academy-styled annual conference organized by the Prostate Cancer Foundation, to focus discussion on the most critical emerging research that have the greatest potential to advance knowledge of prostate cancer biology and treatment. The 2024 CHPCA Meeting was attended by 75 academic investigators and included 37 talks across 8 sessions.

The meeting sessions focused on: novel human, mouse and systems biology research models, novel immunotherapies for prostate cancer, efforts to overcome treatment resistance, the role of metabolism and diet in prostate cancer biology and as a therapeutic target, mechanisms that drive differentiation into neuroendocrine cancer subtypes, the evolving prostate cancer epigenome in disease progression and treatment resistance, and machine learning and advanced computational approaches for precision oncology.

This article summarizes the presentations and discussions from the 2024 CHPCA Meeting. We hope that sharing this knowledge will inspire and accelerate research into new discoveries and solutions for prostate cancer.