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Background and Objective: The prostate-specific membrane antigen (PSMA) radioligand 177 Lu-PSMA-617 (LuPSMA) is approved for treatment of metastatic castration-resistant prostate cancer (mCRPC). PARP inhibitors (PARPi) are approved for patients with mCRPC and mutations in homologous recombination repair (HRR) pathway genes. Both modalities induce DNA damage and therefore may share mechanisms of resistance. We investigated whether PARPi exposure would reduce the subsequent efficacy of LuPSMA., Methods: This retrospective study included 100 patients with a PARPi-qualifying HRR alteration treated with LuPSMA. Clinical outcomes on LuPSMA, including PSA 50 response, PSA progression-free survival (PFS), and overall survival (OS), were compared between those who had not previously received PARPi (PARPi-N) and those who had (PARPi-T). Subgroup analyses were performed for the most frequent HRR alterations (BRCA2 and ATM)., Key Findings and Limitations: PSA 50 responses on LuPSMA were similar between PARPi-N (n = 47) and PARPi-T (n = 53), although PSA PFS was longer in the PARPi-N group (9.1 vs 4.8 mo; p = 0.037). Among patients with BRCA2 alterations, the PARPi-N group had a better PSA 50 response rate (89% vs 35%; p = 0.009), PSA PFS (14 vs 2.9 mo; p = 0.026), and OS (19 vs 5.3 mo; p = 0.10). PARPi exposure did not influence LuPSMA outcomes among patients with ATM alterations. Limitations include the retrospective design and differences in prior lines of therapy between the groups., Conclusions and Clinical Implications: PARPi exposure is associated with inferior LuPSMA outcomes, particularly for patients with BRCA2 alterations. These findings suggest potential cross-resistance and underscore the need for prospective studies assessing the optimal sequencing of these agents., (Copyright © 2025 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

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., (©2024 American Association for Cancer Research.)

Introduction: Papillary urothelial carcinomas are currently graded as either low- or high-grade tumors based on World Health Organization (WHO) 2022 guidelines for genitourinary tumors. However, a minority of tumors are mixed-grade tumors, composed predominantly of low-grade cancer with a minor high-grade component. In the 2022 WHO these cancers are recognized as having outcomes comparable to low-grade cancers, although data to date has been limited., Methods: The pathology records of a large academic institution were searched for mixed-grade, non-muscle invasive papillary carcinomas of the bladder and ureter in order to characterize prognosis of these cancers., Results: Of 136 cancers, the majority (n = 104, 76.5%) were solitary, mixed-grade tumors, while 21 (15.4%) had a concurrent low-grade cancer and 11 (8.1%) had multiple mixed-grade tumors at the time of diagnosis. At follow-up (median 48.3 months, range = 1.3 months-18.1 years), 71 cancers recurred (52.2%): 52 (38.2%) as low- or mixed-grade cancers and 18 (13.2%) as high-grade cancers. There were no instances of stage-progression to >p T2., Conclusions: The clinical outcome of mixed-grade carcinomas was similar to what has been reported for low-grade carcinomas. Based on our results, and prior congruent studies of mixed-grade lesions, these lesions may be regarded as a distinct sub-category with a better prognosis than high-grade tumors., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The VISION and TheraP trials introduced different PET-based criteria for patient selection for treatment with 177 Lu-PSMA-617 (LuPSMA). TheraP used a higher prostate-specific membrane antigen (PSMA) uptake threshold than VISION and required 18 F-FDG PET to exclude patients with discordant findings. Although the screen-failed patients had shorter overall survival (OS) than those treated with LuPSMA, it remains unclear whether their outcomes might have been modified if they had been exposed to LuPSMA. In this study, we evaluated associations between the TheraP eligibility criteria and subgroups and the treatment outcomes of patients who were deemed suitable and treated on the basis of VISION criteria. Methods: Consecutive patients who were treated with LuPSMA and who underwent pretreatment PSMA and 18 F-FDG PET were classified as TheraP-eligible (TheraP-E) and TheraP-ineligible (TheraP-I), the latter of which were subclassified as low PSMA or discordant. Odds ratios for an at least 50% decline in prostate-specific antigen (PSA50) were computed using logistic regression, and hazard ratios (HRs) for PSA progression-free survival (PSA-PFS) and OS were computed using Cox regressions. Multivariable analyses were adjusted for baseline imaging and clinical parameters. Results: Of 75 patients, 31 (41%) were deemed TheraP-I; of those, 24 were subclassified as having discordant disease. TheraP-I patients had a lower PSA50 rate than that of TheraP-E patients (28% vs. 67%; odds ratio, 0.19; 95% CI, 0.06-0.52; P = 0.002) and a higher risk of PSA progression (HR, 2.0; 95% CI, 1.2-3.3; P = 0.007). OS in the TheraP-I group was numerically shorter than in the TheraP-E group, but the comparison was only marginally significant (10.4 mo vs. not reached; HR, 1.9; 95% CI, 1.0-3.7; P = 0.054). TheraP-I patients with low PSMA had no significantly different risk of death ( P = 0.9) from that of TheraP-E patients, but those with discordant findings had higher risk of death (HR, 2.3; 95% CI, 1.1-4.6; P = 0.02). Discordant disease remained prognostic for OS after adjusting for baseline imaging and clinical parameters (HR, 3.0; 95% CI, 1.3-6.8; P = 0.01). Conclusion: In VISION-eligible patients who were treated with LuPSMA, TheraP-I patients with discordant findings had lower PSA50, PSA-PFS, and OS. Our study suggests that the shorter OS of TheraP-I patients is mainly driven by the presence of discordant disease., (© 2025 by the Society of Nuclear Medicine and Molecular Imaging.)

177 Lu-PSMA-617 (LuPSMA) is a newly established treatment for patients with metastatic castration-resistant prostate cancer (mCRPC), but survival outcomes vary widely, and predictors of treatment responses are needed. This study investigated the role of total tumor volumes (TTVs) and new lesions (NLs) determined by LuPSMA SPECT/CT in early cycles to predict subsequent outcomes in a real-world practice setting. Methods: Between June and December 2022, consecutive patients with mCRPC who received at least 2 administrations of LuPSMA with SPECT/CT 24 h after treatment were retrospectively reviewed. We evaluated associations between TTVs and the appearance of NLs at cycles 2 and 3 with subsequent prostate-specific antigen (PSA) progression-free survival and overall survival (OS) using multivariate Cox regression. All analyses were adjusted for changes in PSA level relative to baseline. Results: Sixty-six mCRPC patients (median age, 74 y) received a median of 4 (interquartile range, 3-5) cycles of LuPSMA. Median follow-up starting at cycle 2 was 42 wk (interquartile range, 33-48 wk), with 24 of 66 patients deceased at the time of the analysis. Changes in TTV measured at the start of cycles 2 and 3 relative to baseline correlated significantly with corresponding changes in PSA level ( r = 0.55 and 0.56), but absolute TTVs did not correlate significantly ( r = 0.00 and 0.18). Patients with a higher absolute TTV at the start of cycle 2 had worse PSA progression-free survival and OS (hazard ratio [HR], 1.4 [95% CI, 1.1-1.8] and 2.1 [95% CI, 1.5-2.9]), with consistent results at the start of cycle 3 (HR, 2 [95% CI, 1.4-2.9] and 2 [95% CI, 1.2-3.2]). NLs were identified in 13 of 66 and 11 of 51 patients at the start of cycles 2 and 3. NLs at the start of cycle 2 were associated with worse OS (HR, 5.8 [95% CI, 1.9-17.5]), with consistent results at the start of cycle 3 (HR, 4.9 [95% CI, 1.3-18.6]). In multivariate analysis, a higher TTV and the appearance of NLs at the start of cycles 2 and 3 were independently associated with poorer OS. Conclusion: Higher TTVs and NLs on LuPSMA SPECT/CT at the start of cycles 2 and 3 were independently associated with higher risk of death. These measures provided prognostic information independent of changes in PSA. Development of prognostic and predictive models including TTV, NLs, and PSA changes is warranted., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)

Background: Implications of relabeling grade group (GG) 1 prostate cancer as non-cancer will depend on the recommended active surveillance (AS) strategy. Whether relabeling should prompt de-intensifying, PSA-based active monitoring approaches is unclear. We investigated outcomes of biopsy-based AS strategies vs PSA-based active monitoring for GG1 diagnoses under different patient adherence rates., Methods: We analyzed longitudinal PSA levels and time to GG ≥ 2 reclassification among 850 patients diagnosed with GG1 disease from the Canary Prostate Active Surveillance Study (2008-2013). We then simulated 20,000 patients over 12 years, comparing GG ≥ 2 detection under biennial biopsy against three PSA-based strategies:(1) PSA: biopsy for PSA change ≥20%/year, (2) PSA+MRI: MRI for PSA change ≥20%/year and biopsy for PI-RADS ≥3, and (3) Predicted risk: biopsy for predicted upgrading risk ≥10%., Results: Under biennial biopsies and 20% dropout to active treatment, 17% of patients had a > 2-year delay in GG ≥ 2 detection. The PSA strategy reduced biopsies by 39% but delayed detection in 32% of patients. The PSA+MRI strategy cut biopsies by 52%, with a 34% delay. The predicted risk strategy reduced biopsies by 31%, with only an 8% delay. These findings are robust to biopsy sensitivity and confirmatory biopsy., Conclusions: PSA-based active monitoring could substantially reduce biopsy frequency; however, a precision strategy based on an individual upgrading risk is most likely to minimize delays in disease progression detection. This strategy may be preferred if AS is deintensified under relabeling, provided patient adherence remains unaffected., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background/objectives: Unfortunately, not all metastatic castration resistant prostate cancer (mCRPC) patients receive available life-prolonging systemic therapies, emphasizing the need to optimize mCRPC treatment selections. Better guidelines are necessary to determine genetic testing in prostate cancer., Subjects/methods: In this two-part expert opinion-based guide, we provide an expert consensus opinion on the utilization of germline and somatic testing to detect HRR alterations in patients with mCRPC. This guide was developed by a multidisciplinary expert panel that convened in 2023-2024, including representatives from medical oncology, urology, radiation oncology, pathology, medical genomics, and basic science., Results/conclusion: We argue for the widespread adoption of germline testing in all patients with prostate cancer and for somatic mutations testing in patients at the time of recurrent/metastatic disease. In this first part, we review how genomic testing is performed. We also review how to overcome certain barriers to integrate genetic and biomarker testing into clinical practice., (© 2024. The Author(s).)

Background/objectives: Unfortunately, not all metastatic castration-resistant prostate cancer (mCRPC) patients receive available life-prolonging systemic therapies, emphasizing the need to optimize mCRPC treatment selections. Better guidelines are necessary to determine genetic testing for prostate cancer., Subjects/methods: In this two-part expert opinion-based guide, we provide an expert consensus opinion on the utilization of germline and somatic testing to detect HRR alterations in patients with mCRPC. This guide was developed by a multidisciplinary expert panel that convened in 2023-2024, including representatives from medical oncology, urology, radiation oncology, pathology, medical genomics, and basic science., Results/conclusions: In this second part, we highlight how genetic testing can lead to improved, life-prolonging mCRPC therapeutic strategies based on a review of the recent phase III trials and subsequent regulatory approvals for PARP inhibitors in mCRPC., (© 2024. The Author(s).)

Neuroendocrine (NE) transformation is a mechanism of resistance to targeted therapy in lung and prostate adenocarcinomas leading to poor prognosis. Up to date, even if patients at high risk of transformation can be identified by the occurrence of Tumor Protein P53 (TP53) and Retinoblastoma Transcriptional Corepressor 1 (RB1) mutations in their tumors, no therapeutic strategies are available to prevent or delay histological transformation. Upregulation of the cell cycle kinase Cell Division Cycle 7 (CDC7) occurred in tumors during the initial steps of NE transformation, already after TP53/RB1 co-inactivation, leading to induced sensitivity to the CDC7 inhibitor simurosertib. CDC7 inhibition suppressed NE transdifferentiation and extended response to targeted therapy in in vivo models of NE transformation by inducing the proteasome-mediated degradation of the MYC Proto-Oncogen (MYC), implicated in stemness and histological transformation. Ectopic overexpression of a degradation-resistant MYC isoform reestablished the NE transformation phenotype observed on targeted therapy, even in the presence of simurosertib. CDC7 inhibition also markedly extended response to standard cytotoxics (cisplatin, irinotecan) in lung and prostate small cell carcinoma models. These results nominate CDC7 inhibition as a therapeutic strategy to constrain lineage plasticity, as well as to effectively treat NE tumors de novo or after transformation. As simurosertib clinical efficacy trials are ongoing, this concept could be readily translated for patients at risk of transformation., (© 2024. The Author(s).)

Genomic loss of the transcriptional kinase CDK12 occurs in ~6% of metastatic castration-resistant prostate cancers (mCRPC) and correlates with poor patient outcomes. Prior studies demonstrate that acute CDK12 loss confers a homologous recombination (HR) deficiency (HRd) phenotype via premature intronic polyadenylation (IPA) of key HR pathway genes, including ATM. However, mCRPC patients have not demonstrated benefit from therapies that exploit HRd such as inhibitors of polyADP ribose polymerase (PARP). Based on this discordance, we sought to test the hypothesis that an HRd phenotype is primarily a consequence of acute CDK12 loss and the effect is greatly diminished in prostate cancers adapted to CDK12 loss. Analyses of whole genome sequences (WGS) and RNA sequences (RNAseq) of human mCRPCs determined that tumors with biallelic CDK12 alterations ( CDK12 BAL ) lack genomic scar signatures indicative of HRd, despite carrying bi-allelic loss and the appearance of the hallmark tandem-duplicator phenotype (TDP). Experiments confirmed that acute CDK12 inhibition resulted in aberrant polyadenylation and downregulation of long genes (including BRCA1 and BRCA2 ) but such effects were modest or absent in tumors adapted to chronic CDK12 BAL . One key exception was ATM , which did retain transcript shortening and reduced protein expression in the adapted CDK12 BAL models. However, CDK12 BAL cells demonstrated intact HR as measured by RAD51 foci formation following irradiation. CDK12 BAL cells showed a vulnerability to targeting of CDK13 by sgRNA or CDK12/13 inhibitors and in vivo treatment of prostate cancer xenograft lines showed that tumors with CDK12 BAL responded to the CDK12/13 inhibitor SR4835, while CDK12-intact lines did not. Collectively, these studies show that aberrant polyadenylation and long HR gene downregulation is primarily a consequence of acute CDK12 deficiency, which is largely compensated for in cells that have adapted to CDK12 loss. These results provide an explanation for why PARPi monotherapy has thus far failed to consistently benefit patients with CDK12 alterations, though alternate therapies that target CDK13 or transcription are candidates for future research and testing., Competing Interests: PSN has received fees for advisory work from BMS, Pfizer, and Merck, and research support from Janssen for studies unrelated to the present work. MCH. served as a paid consultant/received honoraria from Pfizer and has received research funding from Merck, Novartis, Genentech, Promicell and Bristol Myers Squibb. EC served as a paid consultant to DotQuant, and received Institutional sponsored research funding unrelated to this work from AbbVie, Gilead, Sanofi, Zenith Epigenetics, Bayer Pharmaceuticals, Forma Therapeutics, Genentech, GSK, Janssen Research, Kronos Bio, Foghorn Therapeutics, K36, and MacroGenics. CM has received funds from Genentech and Novartis unrelated to the present work.

Targeting cell surface molecules using radioligand and antibody-based therapies has yielded considerable success across cancers. However, it remains unclear how the expression of putative lineage markers, particularly cell surface molecules, varies in the process of lineage plasticity, wherein tumor cells alter their identity and acquire new oncogenic properties. A notable example of lineage plasticity is the transformation of prostate adenocarcinoma (PRAD) to neuroendocrine prostate cancer (NEPC)-a growing resistance mechanism that results in the loss of responsiveness to androgen blockade and portends dismal patient survival. To understand how lineage markers vary across the evolution of lineage plasticity in prostate cancer, we applied single-cell analyses to 21 human prostate tumor biopsies and two genetically engineered mouse models, together with tissue microarray analysis on 131 tumor samples. Not only did we observe a higher degree of phenotypic heterogeneity in castrate-resistant PRAD and NEPC than previously anticipated but also found that the expression of molecules targeted therapeutically, namely PSMA , STEAP1 , STEAP2 , TROP2, CEACAM5 , and DLL3 , varied within a subset of gene-regulatory networks (GRNs). We also noted that NEPC and small cell lung cancer subtypes shared a set of GRNs, indicative of conserved biologic pathways that may be exploited therapeutically across tumor types. While this extreme level of transcriptional heterogeneity, particularly in cell surface marker expression, may mitigate the durability of clinical responses to current and future antigen-directed therapies, its delineation may yield signatures for patient selection in clinical trials, potentially across distinct cancer types., Competing Interests: Competing interests statement:P.S.N. has received consulting fees from Janssen, Merck and Bristol Myers Squibb and research support from Janssen for work unrelated to the present studies. S.Z. has received consulting fees from Guidepoint and GLG consulting. J.L.Z. is a current employee of AstraZeneca. M.C.H served as a paid consultant/received honoraria from Pfizer and has received research funding from Merck, Novartis, Genentech, Promicell and Bristol Myers Squibb. C.L.S is on the board of directors of Novartis, is a co-founder of ORIC Pharmaceuticals, and is a co-inventor of the prostate cancer drugs enzalutamide and apalutamide, covered by U.S. patents 7,709,517, 8,183,274, 9,126,941, 8,445,507, 8,802,689, and 9,388,159 filed by the University of California. C.L.S. is on the scientific advisory boards of the following biotechnology companies: Beigene, Blueprint, Cellcarta, Column Group, Foghorn, Housey Pharma, Nextech, PMV.

Molecular profiling studies have shed new light on the complex biology of prostate cancer. Genomic studies have highlighted that structural rearrangements are among the most common recurrent alterations. In addition, both germline and somatic mutations in DNA repair genes are enriched in patients with advanced disease. Primary prostate cancer has long been known to be multifocal, but recent studies demonstrate that a large fraction of prostate cancer shows evidence of multiclonality, suggesting that genetically distinct, independently arising tumor clones coexist. Metastatic prostate cancer shows a high level of morphologic and molecular diversity, which is associated with resistance to systemic therapies. The resulting high level of intratumoral heterogeneity has important implications for diagnosis and poses major challenges for the implementation of molecular studies. Here we provide a concise review of the molecular pathology of prostate cancer, highlight clinically relevant alterations, and discuss opportunities for molecular testing., Competing Interests: Conflicts of interest and sources of funding The authors have no significant relationships with, or financial interest in, any commercial companies pertaining to this article. Research reported in this publication was supported in part by the NIH/NCI (P50CA097186), the U.S. Department of Defense Prostate Cancer Research Program (W81XWH-20-1-0111), and the Safeway Foundation., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Therapeutic approaches targeting proteins on the surface of cancer cells have emerged as an important strategy for precision oncology. To capitalize on the potential impact of drugs targeting surface proteins, detailed knowledge about the expression patterns of the target proteins in tumor tissues is required. In castration-resistant prostate cancer (CRPC), agents targeting prostate-specific membrane antigen (PSMA) have demonstrated clinical activity. However, PSMA expression is lost in a significant number of CRPC tumors. The identification of additional cell surface targets is necessary to develop new therapeutic approaches. Here, we performed a comprehensive analysis of the expression heterogeneity and co-expression patterns of trophoblast cell-surface antigen 2 (TROP2), delta-like ligand 3 (DLL3), and carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) in CRPC samples from a rapid autopsy cohort. We show that DLL3 and CEACAM5 exhibit the highest expression in neuroendocrine prostate cancer (NEPC), while TROP2 is expressed across different CRPC molecular subtypes, except for NEPC. We further demonstrated that AR alterations were associated with higher expression of PSMA and TROP2. Conversely, PSMA and TROP2 expression was lower in RB1-altered tumors. In addition to genomic alterations, we show a tight correlation between epigenetic states, particularly histone H3 lysine 27 methylation (H3K27me3) at the transcriptional start site and gene body of TACSTD2 (encoding TROP2), DLL3, and CEACAM5, and their respective protein expression in CRPC patient-derived xenografts. Collectively, these findings provide insights into patterns and determinants of expression of TROP2, DLL3, and CEACAM5 with implications for the clinical development of cell surface targeting agents in CRPC., (© 2024. The Author(s).)

As the treatment landscape for prostate cancer gradually evolves, the frequency of treatment-induced neuroendocrine prostate cancer (NEPC) and double-negative prostate cancer (DNPC) that is deficient for androgen receptor (AR) and neuroendocrine (NE) markers has increased. These prostate cancer subtypes are typically refractory to AR-directed therapies and exhibit poor clinical outcomes. Only a small range of NEPC/DNPC models exist, limiting our molecular understanding of this disease and hindering our ability to perform preclinical trials exploring novel therapies to treat NEPC/DNPC that are urgently needed in the clinic. Here, we report the development of the CU-PC01 PDX model that represents AR-negative mCRPC with PTEN/RB/PSMA loss and CTNN1B / TP53/BRCA2 genetic variants. The CU-PC01 model lacks classic NE markers, with only focal and/or weak expression of chromogranin A, INSM1 and CD56. Collectively, these findings are most consistent with a DNPC phenotype. Ex vivo and in vivo preclinical studies revealed that CU-PC01 PDX tumours are resistant to mCRPC standard-of-care treatments enzalutamide and docetaxel, mirroring the donor patient's treatment response. Furthermore, short-term CU-PC01 tumour explant cultures indicate this model is initially sensitive to PARP inhibition with olaparib. Thus, the CU-PC01 PDX model provides a valuable opportunity to study AR-negative mCRPC biology and to discover new treatment avenues for this hard-to-treat disease.

Purpose: While 177 Lu-PSMA-617 (LuPSMA) is an effective therapy for many patients with metastatic castration-resistant prostate cancer (mCRPC), biomarkers associated with outcomes are not well defined. We hypothesized that prostate cancer mutational profile may associate with clinical activity of LuPSMA. We devised a study to evaluate associations between mCRPC mutational profile with LuPSMA clinical outcomes., Methods: This was a multicenter retrospective analysis of patients with mCRPC with next-generation sequencing (NGS) who received LuPSMA. PSA 50 response (ie, ≥50% decline in prostate-specific antigen [PSA]) rate, PSA progression free survival (PSA PFS), and overall survival (OS) were compared between genetically defined subgroups., Results: One hundred twenty-six patients with NGS results who received at least one cycle of LuPSMA were identified. The median age was 73 (IQR, 68-78) years, 124 (98.4%) received ≥1 prior androgen receptor-signaling inhibitor, and 121 (96%) received ≥1 taxane-based chemotherapy regimen. Fifty-eight (46%) patients with a DNA damage repair gene mutation (DNA damage response group) and 59 (46.8%) with a mutation in TP53 , RB1 , or PTEN tumor suppressor genes (TSG group) were identified. After adjusting for relevant confounders, the presence of ≥1 TSG mutation was associated with shorter PSA PFS (hazard ratio [HR], 1.93 [95% CI, 1.05 to 3.54]; P = .034) and OS (HR, 2.65 [95% CI, 1.15 to 6.11]; P = .023). There was improved OS favoring the DNA damage response group (HR, 0.37 [95% CI, 0.14 to 0.97]; P = .044) on multivariable analysis. Univariate analysis of patients with ATM mutations had significantly higher rates of PSA 50 response, PSA PFS, and OS., Conclusion: Outcomes on LuPSMA varied on the basis of mutational profile. Prospective studies to define the clinical activity of LuPSMA in predefined genomic subgroups are justified.

Castration-resistant prostate cancer (CRPC) is a heterogeneous disease associated with phenotypic subtypes that drive therapy response and outcome differences. Histologic transformation to castration-resistant neuroendocrine prostate cancer (CRPC-NE) is associated with distinct epigenetic alterations, including changes in DNA methylation. The current diagnosis of CRPC-NE is challenging and relies on metastatic biopsy. We developed a targeted DNA methylation assay to detect CRPC-NE using plasma cell-free DNA (cfDNA). The assay quantifies tumor content and provides a phenotype evidence score that captures diverse CRPC phenotypes, leveraging regions to inform transcriptional state. We tested the design in independent clinical cohorts (n = 222 plasma samples) and qualified it achieving an AUC > 0.93 for detecting pathology-confirmed CRPC-NE (n = 136). Methylation-defined cfDNA tumor content was associated with clinical outcomes in two prospective phase II clinical trials geared towards aggressive variant CRPC and CRPC-NE. These data support the application of targeted DNA methylation for CRPC-NE detection and patient stratification., Significance: Neuroendocrine prostate cancer is an aggressive subtype of treatment-resistant prostate cancer. Early detection is important, but the diagnosis currently relies on metastatic biopsy. We describe the development and validation of a plasma cell-free DNA targeted methylation panel that can quantify tumor fraction and identify patients with neuroendocrine prostate cancer noninvasively. This article is featured in Selected Articles from This Issue, p. 384., (©2023 The Authors; Published by the American Association for Cancer Research.)

Available genetically defined cancer models are limited in genotypic and phenotypic complexity and underrepresent the heterogeneity of human cancer. Here, we describe a combinatorial genetic strategy applied to an organoid transformation assay to rapidly generate diverse, clinically relevant bladder and prostate cancer models. Importantly, the clonal architecture of the resultant tumors can be resolved using single-cell or spatially resolved next-generation sequencing to uncover polygenic drivers of cancer phenotypes., (© 2024. The Author(s).)

Lysine-specific demethylase 1 (LSD1 or KDM1A ) has emerged as a critical mediator of tumor progression in metastatic castration-resistant prostate cancer (mCRPC). Among mCRPC subtypes, neuroendocrine prostate cancer (NEPC) is an exceptionally aggressive variant driven by lineage plasticity, an adaptive resistance mechanism to androgen receptor axis-targeted therapies. Our study shows that LSD1 expression is elevated in NEPC and associated with unfavorable clinical outcomes. Using genetic approaches, we validated the on-target effects of LSD1 inhibition across various models. We investigated the therapeutic potential of bomedemstat, an orally bioavailable, irreversible LSD1 inhibitor with low nanomolar potency. Our findings demonstrate potent antitumor activity against CRPC models, including tumor regressions in NEPC patient-derived xenografts. Mechanistically, our study uncovers that LSD1 inhibition suppresses the neuronal transcriptional program by downregulating ASCL1 through disrupting LSD1:INSM1 interactions and de-repressing YAP1 silencing. Our data support the clinical development of LSD1 inhibitors for treating CRPC - especially the aggressive NE phenotype., Statement of Significance: Neuroendocrine prostate cancer presents a clinical challenge due to the lack of effective treatments. Our research demonstrates that bomedemstat, a potent and selective LSD1 inhibitor, effectively combats neuroendocrine prostate cancer by downregulating the ASCL1- dependent NE transcriptional program and re-expressing YAP1.

Fatty acid synthase (FASN) catalyzes the synthesis of long-chain saturated fatty acids and is overexpressed during prostatic tumorigenesis, where it is the therapeutic target in several ongoing trials. However, the mechanism of FASN upregulation in prostate cancer remains unclear. Here, we examine FASN gene CpG methylation pattern by InfiniumEPIC profiling and whole-genome bisulfite sequencing across multiple racially diverse primary and metastatic prostate cancer cohorts, comparing with FASN protein expression as measured by digitally quantified IHC assay and reverse phase protein array analysis or FASN gene expression. We demonstrate that the FASN gene body is hypomethylated and overexpressed in primary prostate tumors compared with benign tissue, and FASN gene methylation is significantly inversely correlated with FASN protein or gene expression in both primary and metastatic prostate cancer. Primary prostate tumors with ERG gene rearrangement have increased FASN expression and we find evidence of FASN hypomethylation in this context. FASN expression is also significantly increased in prostate tumors from carriers of the germline HOXB13 G84E mutation compared with matched controls, consistent with a report that HOXB13 may contribute to epigenetic regulation of FASN in vitro. However, in contrast to previous studies, we find no significant association of FASN expression or methylation with self-identified race in models that include ERG status across two independent primary tumor cohorts. Taken together, these data support a potential epigenetic mechanism for FASN regulation in the prostate which may be relevant for selecting patients responsive to FASN inhibitors., Significance: Here, we leverage multiple independent primary and metastatic prostate cancer cohorts to demonstrate that FASN gene body methylation is highly inversely correlated with FASN gene and protein expression. This finding may shed light on epigenetic mechanisms of FASN regulation in prostate cancer and provides a potentially useful biomarker for selecting patients in future trials of FASN inhibitors., (© 2024 The Authors; Published by the American Association for Cancer Research.)

HOXB13 is a key lineage homeobox transcription factor that plays a critical role in the differentiation of the prostate gland. Several studies have suggested that HOXB13 alterations may be involved in prostate cancer development and progression. Despite its potential biological relevance, little is known about the expression of HOXB13 across the disease spectrum of prostate cancer. To this end, we validated a HOXB13 antibody using genetic controls and investigated HOXB13 protein expression in murine and human developing prostates, localized prostate cancers, and metastatic castration-resistant prostate cancers. We observed that HOXB13 expression increases during later stages of murine prostate development. All localized prostate cancers showed HOXB13 protein expression. Interestingly, lower HOXB13 expression levels were observed in higher-grade tumors, although no significant association between HOXB13 expression and recurrence or disease-specific survival was found. In advanced metastatic prostate cancers, HOXB13 expression was retained in the majority of tumors. While we observed lower levels of HOXB13 protein and mRNA levels in tumors with evidence of lineage plasticity, 84% of androgen receptor-negative castration-resistant prostate cancers and neuroendocrine prostate cancers (NEPCs) retained detectable levels of HOXB13. Notably, the reduced expression observed in NEPCs was associated with a gain of HOXB13 gene body CpG methylation. In comparison to the commonly used prostate lineage marker NKX3.1, HOXB13 showed greater sensitivity in detecting advanced metastatic prostate cancers. Additionally, in a cohort of 837 patients, 383 with prostatic and 454 with non-prostatic tumors, we found that HOXB13 immunohistochemistry had a 97% sensitivity and 99% specificity for prostatic origin. Taken together, our studies provide valuable insight into the expression pattern of HOXB13 during prostate development and cancer progression. Furthermore, our findings support the utility of HOXB13 as a diagnostic biomarker for prostate cancer, particularly to confirm the prostatic origin of advanced metastatic castration-resistant tumors. © 2023 The Pathological Society of Great Britain and Ireland., (© 2023 The Pathological Society of Great Britain and Ireland.)

Therapeutic approaches targeting proteins on the surface of cancer cells have emerged as an important strategy for precision oncology. To fully capitalize on the potential impact of drugs targeting surface proteins, detailed knowledge about the expression patterns of the target proteins in tumor tissues is required. In castration-resistant prostate cancer (CRPC), agents targeting prostate-specific membrane antigen (PSMA) have demonstrated clinical activity. However, PSMA expression is lost in a significant number of CRPC tumors, and the identification of additional cell surface targets is necessary in order to develop new therapeutic approaches. Here, we performed a comprehensive analysis of the expression and co-expression patterns of trophoblast cell-surface antigen 2 (TROP2), delta-like ligand 3 (DLL3), and carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) in CRPC samples from a rapid autopsy cohort. We show that DLL3 and CEACAM5 exhibit the highest expression in neuroendocrine prostate cancer (NEPC), while TROP2 is expressed across different CRPC molecular subtypes, except for NEPC. We observed variable intra-tumoral and inter-tumoral heterogeneity and no dominant metastatic site predilections for TROP2, DLL3, and CEACAM5. We further show that AR amplifications were associated with higher expression of PSMA and TROP2 but lower DLL3 and CEACAM5 levels. Conversely, PSMA and TROP2 expression was lower in RB1 -altered tumors. In addition to genomic alterations, we demonstrate a tight correlation between epigenetic states, particularly histone H3 lysine 27 methylation (H3K27me3) at the transcriptional start site and gene body of TACSTD2 (encoding TROP2) , DLL3 , and CEACAM5 , and their respective protein expression in CRPC patient-derived xenografts. Collectively, these findings provide novel insights into the patterns and determinants of expression of TROP2, DLL3, and CEACAM5 with important implications for the clinical development of cell surface targeting agents in CRPC., Competing Interests: Conflict of interest statement: J. Zhao is currently an employee at Astra Zeneca. L.D. True is a co-founder and has equity in Alpenglow Biosciences. H.H. Cheng was a paid consultant to AstraZeneca in the past and has received research funding from Astellas, Clovis Oncology, Color Foundation, Janssen, Medivation, Promontory Therapeutics, Sanofi, and royalties from UpToDate. E.Y.Yu served as paid consultant/received honoraria Amgen, AstraZeneca, Bayer, Churchill, Dendreon, EMD Serono, Incyte, Janssen, Merck, Clovis, Pharmacyclics, QED, Seattle Genetics, and Tolmar and received research funding from Bayer, Daiichi-Sankyo, Dendreon, Merck, Taiho, and Seattle Genetics. R.B. Montgomery received research funding from AstraZeneca, ESSA, Ferring and Janssen Oncology. J.E. Hawley received consulting fees from ImmunityBio and research funding to her institution from Bristol Myers Squibb, Astra Zeneca, Vaccitech, Crescendo and Macrogenics. J. K. Lee has received research funding from Immunomedics and serves as a scientific advisor for and has equity in PromiCell Therapeutics. E. Corey received sponsored research funding from AbbVie, Astra Zeneca, Foghorn, Kronos, MacroGenics, Bayer Pharmaceuticals, Forma Pharmaceuticals, Janssen Research, Gilead, Arvina, and Zenith Epigenetics. J.M. Lang served as paid consultant/received honoraria from Sanofi, AstraZeneca, Gilead, Pfizer, Astellas, Seattle Genetics, Janssen, and Immunomedics. C.L. Sawyers serves on the board of directors of Novartis, is a cofounder of ORIC Pharmaceuticals, and is a co-inventor of enzalutamide and apalutamide. He is a science adviser to Arsenal, Beigene, Blueprint, Column Group, Foghorn, Housey Pharma, Nextech, KSQ, and PMV. M.T. Schweizer is a paid consultant/received honoraria from Sanofi, AstraZeneca, PharmaIn, and Resverlogix and has received research funding from Novartis, Zenith Epigenetics, Bristol Myers Squibb, Merck, Immunomedics, Janssen, AstraZeneca, Pfizer, Hoffman-La Roche, Tmunity, SignalOne Bio, Epigenetix, Xencor, Incyte and Ambrx, Inc. P.S. Nelson served as a paid advisor for Bristol Myers Squibb, Pfizer, and Janssen. All other authors declare no potential conflicts of interest. M.C. Haffner served as paid consultant/received honoraria from Pfizer and has received research funding from Merck, Genentech, Promicell and Bristol Myers Squibb.

Background: Nectin-4 and Trop-2 are transmembrane targets of FDA-approved antibody-drug conjugates (ADC) Enfortumab-vedotin (EV) and Sacituzumab govitecan (SG), respectively, for the treatment of metastatic urothelial carcinoma (mUC). The expression and role of Nectin-4 and Trop-2 in mUC variant histology is poorly described., Materials and Methods: We evaluate membranous and cytoplasmic protein expression, and mRNA levels of Nectin-4 and Trop-2 within matched primary and metastatic mUC samples to determine heterogeneity of ADC targets in mUC variants., Results: Patients with mUC were consented for rapid autopsy immediately after death. Tissues from matched primary and metastatic lesions were collected. A total of 67 specimens from 20 patients were analyzed: 27 were UC, 17 plasmacytoid (PUC), 18 UC with squamous differentiation (UCSD), and 5 neuroendocrine (NE); 10 from primary and 57 from metastatic sites. All histology except NE expressed moderate-high levels of Nectin-4 and Trop-2 by both immunohistochemistry and RNAseq. Nectin-4 demonstrated prominent cytoplasmic staining in metastatic PUC and UCSD. Trop-2 demonstrated strong cytoplasmic and membrane staining in primary and metastatic tumors. Interestingly, Nectin-4 and Trop-2 expression are positively correlated at both mRNA and protein levels., Conclusion: UC and non-NE variants express notable level of Nectin-4 and Trop-2 in both primary and metastatic lesions. Membrane staining of Nectin-4 and Trop-2 is present but cytoplasmic staining is a more common event in both mUC and mUC variant histology. These findings support evaluation of EV and SG in heavily treated variant histology BC and urge attention on the clinical relevance of cytoplasmic localization of ADC targets., Competing Interests: Disclosure Evan Yu: Institutional grants: Daiichi-Sankyo, Taiho, Dendreon, Merck, Seattle Genetics, Blue Earth, Bayer - DAROL and citDNA, Lantheus Consulting with honorarium (in the last 3 years): Jansen, Merck, Advanced Accelerator Applications, Bayer, Exelixis, Clovis, Abbvie, Sanofi-Genzyme Funda Vakar-Lopez: AstraZeneca - Virtual Advisory Board Member on metastatic urothelial cancer Petros Grivas: Institutional grants: Bavarian Nordic; Bristol-Myers Squibb; Clovis Oncology; Debiopharm; Merck KGaA; Gilead; Pfizer; MSD; QED Therapeutics; GlaxoSmithKline; G1 Therapeutics; Mirati Therapeutics Consulting: Aadi Bioscience; AstraZeneca; Asieris Pharmaceuticals, Astellas Pharma, BMS; Boston Gene, CG Oncology, Dyania Health; Exelixis; Lucence Health; Fresenius Kabi, G1 Therapeutics; Gilead; Guardant Health; ImmunityBio; Infinity Pharmaceuticals; Janssen; Merck KGaA; Mirati Therapeutics; MSD; Genentech/Roche; Pfizer; PureTech; Regeneron Pharmaceuticals; QED Therapeutics; Seattle Genetics, Strata Oncology, 4D Pharma PLC, UroGen, Silverback Therapeutics Bruce Montgomery: Institutional grants: AstraZeneca, Janssen Oncology, Clovis Oncology, Astellas Pharma, BeiGene John K. Lee: Institutional grants: Immunomedics Michael Schweizer: Institutional grants: Zenith Epigenetics, Bristol Myers Squibb, Merck, Immunomedics, Janssen, AstraZeneca, Pfizer, Madison Vaccines, Hoffman-La Roche, Tmunity, SignalOne Bio and Ambrx, Inc. Paid consultant and/or received Honoria: Sanofi, AstraZeneca, PharmaIn and Resverlogix. Jonathan Wright Institutional grants: Merck, Veracyte, Pacific Edge, Janssen, Nucleix. Consultant: Immunity Bio Royalties: UpToDate Other authors declare no potential conflicts of interest., (Copyright © 2023 Elsevier Inc. All rights reserved.)

SND1 and MTDH are known to promote cancer and therapy resistance, but their mechanisms and interactions with other oncogenes remain unclear. Here, we show that oncoprotein ERG interacts with SND1/MTDH complex through SND1's Tudor domain. ERG, an ETS-domain transcription factor, is overexpressed in many prostate cancers. Knocking down SND1 in human prostate epithelial cells, especially those overexpressing ERG, negatively impacts cell proliferation. Transcriptional analysis shows substantial overlap in genes regulated by ERG and SND1. Mechanistically, we show that ERG promotes nuclear localization of SND1/MTDH. Forced nuclear localization of SND1 prominently increases its growth promoting function irrespective of ERG expression. In mice, prostate-specific Snd1 deletion reduces cancer growth and tumor burden in a prostate cancer model (PB-Cre/Pten flox/flox /ERG mice), Moreover, we find a significant overlap between prostate transcriptional signatures of ERG and SND1. These findings highlight SND1's crucial role in prostate tumorigenesis, suggesting SND1 as a potential therapeutic target in prostate cancer., (© 2023. The Author(s).)

When compared to other malignancies, the tumor microenvironment (TME) of primary and castration-resistant prostate cancer (CRPC) is relatively devoid of immune infiltrates. While androgen deprivation therapy (ADT) induces a complex immune infiltrate in localized prostate cancer, the composition of the TME in metastatic castration-sensitive prostate cancer (mCSPC), and the effects of ADT and other treatments in this context are poorly understood. Here, we perform a comprehensive single-cell RNA sequencing (scRNA-seq) profiling of metastatic sites from patients participating in a phase 2 clinical trial (NCT03951831) that evaluated standard-of-care chemo-hormonal therapy combined with anti-PD-1 immunotherapy. We perform a longitudinal, protein activity-based analysis of TME subpopulations, revealing immune subpopulations conserved across multiple metastatic sites. We also observe dynamic changes in these immune subpopulations in response to treatment and a correlation with clinical outcomes. Our study uncovers a therapy-resistant, transcriptionally distinct tumor subpopulation that expands in cell number in treatment-refractory patients., Competing Interests: Declaration of interests Dr. Hawley has served as a paid consultant to Seagen, Daiichi Sankyo, and ImmunityBio and has received sponsored research funding to her institution from Astra Zeneca, Bristol Meyers Squibb, Crescendo Biologics, Macrogenics, and Vaccitech. Dr. Drake is a co-inventor on patents licensed from JHU to BMS and Janssen and is currently an employee of Janssen Research. Dr. Califano is founder, equity holder, and consultant of DarwinHealth Inc., a company that has licensed some of the algorithms used in this manuscript from Columbia University. Columbia University is also an equity holder in DarwinHealth Inc. Dr. Lowy is an employee and stockholder of Regeneron Pharmaceuticals., (Copyright © 2023. Published by Elsevier Inc.)

Advanced prostate cancers are treated with therapies targeting the androgen receptor (AR) signaling pathway. While many tumors initially respond to AR inhibition, nearly all develop resistance. It is critical to understand how prostate tumor cells respond to AR inhibition in order to exploit therapy-induced phenotypes prior to the outgrowth of treatment-resistant disease. Here, we comprehensively characterize the effects of AR blockade on prostate cancer metabolism using transcriptomics, metabolomics, and bioenergetics approaches. The metabolic response to AR inhibition is defined by reduced glycolysis, robust elongation of mitochondria, and increased reliance on mitochondrial oxidative metabolism. We establish DRP1 activity and MYC signaling as mediators of AR-blockade-induced metabolic phenotypes. Rescuing DRP1 phosphorylation after AR inhibition restores mitochondrial fission, while rescuing MYC restores glycolytic activity and prevents sensitivity to complex I inhibition. Our study provides insight into the regulation of treatment-induced metabolic phenotypes and vulnerabilities in prostate cancer., Competing Interests: Declaration of interests P.C.B. sits on the scientific advisory boards of Sage Bionetworks, BioSymetrics, Inc., and Intersect Diagnostics, Inc., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Small cell lung cancer (SCLC) exists broadly in four molecular subtypes: ASCL1, NEUROD1, POU2F3 and Inflammatory. Initially, SCLC subtypes were thought to be mutually exclusive, but recent evidence shows intra-tumoural subtype heterogeneity and plasticity between subtypes. Here, using a CRISPR-based autochthonous SCLC genetically engineered mouse model to study the consequences of KDM6A/UTX inactivation, we show that KDM6A inactivation induced plasticity from ASCL1 to NEUROD1 resulting in SCLC tumours that express both ASCL1 and NEUROD1. Mechanistically, KDM6A normally maintains an active chromatin state that favours the ASCL1 subtype with its loss decreasing H3K4me1 and increasing H3K27me3 at enhancers of neuroendocrine genes leading to a cell state that is primed for ASCL1-to-NEUROD1 subtype switching. This work identifies KDM6A as an epigenetic regulator that controls ASCL1 to NEUROD1 subtype plasticity and provides an autochthonous SCLC genetically engineered mouse model to model ASCL1 and NEUROD1 subtype heterogeneity and plasticity, which is found in 35-40% of human SCLCs., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

The androgen receptor (AR) pathway regulates key cell survival programs in prostate epithelium. The AR represents a near-universal driver and therapeutic vulnerability in metastatic prostate cancer, and targeting AR has a remarkable therapeutic index. Though most approaches directed toward AR focus on inhibiting AR signaling, laboratory and now clinical data have shown that high dose, supraphysiological androgen treatment (SPA) results in growth repression and improved outcomes in subsets of patients with prostate cancer. A better understanding of the mechanisms contributing to SPA response and resistance could help guide patient selection and combination therapies to improve efficacy. To characterize SPA signaling, we integrated metrics of gene expression changes induced by SPA together with cistrome data and protein-interactomes. These analyses indicated that the dimerization partner, RB-like, E2F, and multivulval class B (DREAM) complex mediates growth repression and downregulation of E2F targets in response to SPA. Notably, prostate cancers with complete genomic loss of RB1 responded to SPA treatment, whereas loss of DREAM complex components such as RBL1/2 promoted resistance. Overexpression of MYC resulted in complete resistance to SPA and attenuated the SPA/AR-mediated repression of E2F target genes. These findings support a model of SPA-mediated growth repression that relies on the negative regulation of MYC by AR leading to repression of E2F1 signaling via the DREAM complex. The integrity of MYC signaling and DREAM complex assembly may consequently serve as determinants of SPA responses and as pathways mediating SPA resistance., Significance: Determining the molecular pathways by which supraphysiological androgens promote growth arrest and treatment responses in prostate cancer provides opportunities for biomarker-selected clinical trials and the development of strategies to augment responses., (©2023 The Authors; Published by the American Association for Cancer Research.)

Pathologic examination of prostate biopsies is time consuming due to the large number of slides per case. In this retrospective study, we validate a deep learning-based classifier for prostate cancer (PCA) detection and Gleason grading (AI tool) in biopsy samples. Five external cohorts of patients with multifocal prostate biopsy were analyzed from high-volume pathology institutes. A total of 5922 H&E sections representing 7473 biopsy cores from 423 patient cases (digitized using three scanners) were assessed concerning tumor detection. Two tumor-bearing datasets (core n = 227 and 159) were graded by an international group of pathologists including expert urologic pathologists (n = 11) to validate the Gleason grading classifier. The sensitivity, specificity, and NPV for the detection of tumor-bearing biopsies was in a range of 0.971-1.000, 0.875-0.976, and 0.988-1.000, respectively, across the different test cohorts. In several biopsy slides tumor tissue was correctly detected by the AI tool that was initially missed by pathologists. Most false positive misclassifications represented lesions suspicious for carcinoma or cancer mimickers. The quadratically weighted kappa levels for Gleason grading agreement for single pathologists was 0.62-0.80 (0.77 for AI tool) and 0.64-0.76 (0.72 for AI tool) for the two grading datasets, respectively. In cases where consensus for grading was reached among pathologists, kappa levels for AI tool were 0.903 and 0.855. The PCA detection classifier showed high accuracy for PCA detection in biopsy cases during external validation, independent of the institute and scanner used. High levels of agreement for Gleason grading were indistinguishable between experienced genitourinary pathologists and the AI tool., (© 2023. Nature Publishing Group UK.)

In lung and prostate adenocarcinomas, neuroendocrine (NE) transformation to an aggressive derivative resembling small cell lung cancer (SCLC) is associated with poor prognosis. We previously described dependency of SCLC on the nuclear transporter exportin 1. Here, we explored the role of exportin 1 in NE transformation. We observed up-regulated exportin 1 in lung and prostate pretransformation adenocarcinomas. Exportin 1 was up-regulated after genetic inactivation of TP53 and RB1 in lung and prostate adenocarcinoma cell lines, accompanied by increased sensitivity to the exportin 1 inhibitor selinexor in vitro. Exportin 1 inhibition prevented NE transformation in different TP53/RB1-inactivated prostate adenocarcinoma xenograft models that acquire NE features upon treatment with the aromatase inhibitor enzalutamide and extended response to the EGFR inhibitor osimertinib in a lung cancer transformation patient-derived xenograft (PDX) model exhibiting combined adenocarcinoma/SCLC histology. Ectopic SOX2 expression restored the enzalutamide-promoted NE phenotype on adenocarcinoma-to-NE transformation xenograft models despite selinexor treatment. Selinexor sensitized NE-transformed lung and prostate small cell carcinoma PDXs to standard cytotoxics. Together, these data nominate exportin 1 inhibition as a potential therapeutic target to constrain lineage plasticity and prevent or treat NE transformation in lung and prostate adenocarcinoma.

We uncover a tumor-suppressive process in urothelium called transcriptional-translational conflict caused by deregulation of the central chromatin remodeling component ARID1A. Loss of Arid1a triggers an increase in a nexus of pro-proliferation transcripts, but a simultaneous inhibition of the eukaryotic elongation factor 2 (eEF2), which results in tumor suppression. Resolution of this conflict through enhancing translation elongation speed enables the efficient and precise synthesis of a network of poised mRNAs resulting in uncontrolled proliferation, clonogenic growth, and bladder cancer progression. We observe a similar phenomenon in patients with ARID1A-low tumors, which also exhibit increased translation elongation activity through eEF2. These findings have important clinical implications because ARID1A-deficient, but not ARID1A-proficient, tumors are sensitive to pharmacologic inhibition of protein synthesis. These discoveries reveal an oncogenic stress created by transcriptional-translational conflict and provide a unified gene expression model that unveils the importance of the crosstalk between transcription and translation in promoting cancer., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Amphicrine prostate carcinoma (AMPC) is a poorly defined subset of prostate cancer in which cells co-express luminal prostate epithelial and neuroendocrine markers. The optimal treatment strategy is unknown. We sought to further characterize the clinical, histomorphologic, and molecular characteristics of AMPC and to identify areas of potential future treatment investigations., Methods: We retrospectively identified 17 cases of AMPC at a single institution, defined as synaptophysin expression in >70% of cells and co-expression of androgen receptor (AR) signaling markers (either AR, PSA, or NKX3.1) in >50% of cells. Clinical and histologic features of AMPC cases as well as response to treatment and clinical outcomes were described., Results: Five AMPC cases arose de novo in the absence of prior systemic treatment and behaved distinctly from cases that were treatment-emergent. In these de novo cases, despite expression of neuroendocrine markers, prognosis appeared more favorable than high-grade neuroendocrine carcinoma, with two (40%) patients with de novo metastatic disease, universal response to androgen deprivation therapy, and no deaths at a median follow-up of 12.3 months. Treatment-emergent AMPC arose a median of 41.1 months after androgen deprivation therapy initiation and was associated with poor response to therapy., Conclusions: We show that amphicrine prostate cancer is a unique entity and differs in clinical and molecular features from high-grade neuroendocrine carcinomas of the prostate. Our study highlights the need to recognize AMPC as a unique molecularly defined subgroup of prostate cancer., (© 2023 Wiley Periodicals LLC.)

Available genetically-defined cancer models are limited in genotypic and phenotypic complexity and underrepresent the heterogeneity of human cancer. Herein, we describe a combinatorial genetic strategy applied to an organoid transformation assay to rapidly generate diverse, clinically relevant bladder and prostate cancer models. Importantly, the clonal architecture of the resultant tumors can be resolved using single-cell or spatially resolved next-generation sequencing to uncover polygenic drivers of cancer phenotypes.

Six transmembrane epithelial antigen of the prostate 1 (STEAP1) is a cell surface antigen for therapeutic targeting in prostate cancer. Here, we report broad expression of STEAP1 relative to prostate-specific membrane antigen (PSMA) in lethal metastatic prostate cancers and the development of a STEAP1-directed chimeric antigen receptor (CAR) T cell therapy. STEAP1 CAR T cells demonstrate reactivity in low antigen density, antitumor activity across metastatic prostate cancer models, and safety in a human STEAP1 knock-in mouse model. STEAP1 antigen escape is a recurrent mechanism of treatment resistance and is associated with diminished tumor antigen processing and presentation. The application of tumor-localized interleukin-12 (IL-12) therapy in the form of a collagen binding domain (CBD)-IL-12 fusion protein combined with STEAP1 CAR T cell therapy enhances antitumor efficacy by remodeling the immunologically cold tumor microenvironment of prostate cancer and combating STEAP1 antigen escape through the engagement of host immunity and epitope spreading., (© 2023. The Author(s).)

Prostate-specific membrane antigen (PSMA) is an important cell surface target in prostate cancer. There are limited data on the heterogeneity of PSMA tissue expression in metastatic castration-resistant prostate cancer (mCRPC). Furthermore, the mechanisms regulating PSMA expression (encoded by the FOLH1 gene) are not well understood. Here, we demonstrate that PSMA expression is heterogeneous across different metastatic sites and molecular subtypes of mCRPC. In a rapid autopsy cohort in which multiple metastatic sites per patient were sampled, we found that 13 of 52 (25%) cases had no detectable PSMA and 23 of 52 (44%) cases showed heterogeneous PSMA expression across individual metastases, with 33 (63%) cases harboring at least 1 PSMA-negative site. PSMA-negative tumors displayed distinct transcriptional profiles with expression of druggable targets such as MUC1. Loss of PSMA was associated with epigenetic changes of the FOLH1 locus, including gain of CpG methylation and loss of histone 3 lysine 27 (H3K27) acetylation. Treatment with histone deacetylase (HDAC) inhibitors reversed this epigenetic repression and restored PSMA expression in vitro and in vivo. Collectively, these data provide insights into the expression patterns and regulation of PSMA in mCRPC and suggest that epigenetic therapies - in particular, HDAC inhibitors - can be used to augment PSMA levels.

Necrosis in the tumor interior is a common feature of aggressive cancers that is associated with poor clinical prognosis and the development of metastasis. How the necrotic core promotes metastasis remains unclear. Here, we report that emergence of necrosis inside the tumor is correlated temporally with increased tumor dissemination in a rat breast cancer model and in human breast cancer patients. By performing spatially focused transcriptional profiling, we identified angiopoietin-like 7 (Angptl7) as a tumor-specific factor localized to the perinecrotic zone. Functional studies showed that Angptl7 loss normalizes central necrosis, perinecrotic dilated vessels, metastasis, and reduces circulating tumor cell counts to nearly zero. Mechanistically, Angptl7 promotes vascular permeability and supports vascular remodeling in the perinecrotic zone. Taken together, these findings show that breast tumors actively produce factors controlling central necrosis formation and metastatic dissemination from the tumor core.

Advanced prostate cancers comprise distinct phenotypes, but tumor classification remains clinically challenging. Here, we harnessed circulating tumor DNA (ctDNA) to study tumor phenotypes by ascertaining nucleosome positioning patterns associated with transcription regulation. We sequenced plasma ctDNA whole genomes from patient-derived xenografts representing a spectrum of androgen receptor active (ARPC) and neuroendocrine (NEPC) prostate cancers. Nucleosome patterns associated with transcriptional activity were reflected in ctDNA at regions of genes, promoters, histone modifications, transcription factor binding, and accessible chromatin. We identified the activity of key phenotype-defining transcriptional regulators from ctDNA, including AR, ASCL1, HOXB13, HNF4G, and GATA2. To distinguish NEPC and ARPC in patient plasma samples, we developed prediction models that achieved accuracies of 97% for dominant phenotypes and 87% for mixed clinical phenotypes. Although phenotype classification is typically assessed by IHC or transcriptome profiling from tumor biopsies, we demonstrate that ctDNA provides comparable results with diagnostic advantages for precision oncology., Significance: This study provides insights into the dynamics of nucleosome positioning and gene regulation associated with cancer phenotypes that can be ascertained from ctDNA. New methods for classification in phenotype mixtures extend the utility of ctDNA beyond assessments of somatic DNA alterations with important implications for molecular classification and precision oncology. This article is highlighted in the In This Issue feature, p. 517., (©2022 The Authors; Published by the American Association for Cancer Research.)

Background: Bipolar androgen therapy (BAT) results in rapid fluctuation of testosterone (T) between near-castrate and supraphysiological levels and has shown promise in metastatic castration-resistant prostate cancer (mCRPC). Its clinical effects may be mediated through induction of DNA damage, and preclinical studies suggest synergy with PARP inhibitors., Patients and Methods: This was a single-center, Phase II trial testing olaparib plus BAT (T cypionate/enanthate 400 mg every 28 days) with ongoing androgen deprivation. Planned recruitment was 30 subjects (equal proportions with/without homologous recombination repair [HRR] gene mutations) with mCRPC post abiraterone and/or enzalutamide. The primary objective was to determine PSA 50 response (PSA decline ≥50% from baseline) rate at 12-weeks. The primary analysis utilized the entire (intent-to-treat [ITT]) cohort, with those dropping out early counted as non-responders. Secondary/exploratory analyses were in those treated beyond 12-weeks (response-evaluable cohort)., Results: Thirty-six patients enrolled and 6 discontinued prior to response assessment. In the ITT cohort, PSA 50 response rate at 12-weeks was 11/36 (31%; 95% CI 17-48%), and 16/36 (44%, 95% CI 28-62%) had a PSA50 response at any time on-study. After a median follow-up of 19 months, the median clinical/radiographic progression-free survival in the ITT cohort was 13.0 months (95% CI 7-17). Clinical outcomes were similar regardless of HRR gene mutational status., Conclusions: BAT plus olaparib is associated with high response rates and long PFS. Clinical benefit was observed regardless of HRR gene mutational status., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Basal cell carcinoma (BCC) of the prostate is a rare tumor. Compared with the more common acinar adenocarcinoma (AAC) of the prostate, BCCs show features of basal cell differentiation and are thought to be biologically distinct from AAC. The spectrum of molecular alterations of BCC has not been comprehensively described, and genomic studies are lacking. Herein, whole genome sequencing was performed on archival formalin-fixed, paraffin-embedded specimens of two cases with BCC. Prostatic BCCs were characterized by an overall low copy number and mutational burden. Recurrent copy number loss of chromosome 16 was observed. In addition, putative driver gene alterations in KIT, DENND3, PTPRU, MGA, and CYLD were identified. Mechanistically, depletion of the CYLD protein resulted in increased proliferation of prostatic basal cells in vitro. Collectively, these studies show that prostatic BCC displays distinct genomic alterations from AAC and highlight a potential role for loss of chromosome 16 in the pathogenesis of this rare tumor type., (Copyright © 2023 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Genomic studies have demonstrated a high level of intra-tumoral heterogeneity in prostate cancer. There is strong evidence suggesting that individual tumor foci can arise as genetically distinct, clonally independent lesions. However, recent studies have also demonstrated that adjacent Gleason pattern (GP) 3 and GP4 lesions can originate from the same clone but follow divergent genetic and morphologic evolution. The clonal relationship of adjacent GP3 and GP5 lesions has thus far not been investigated. Here we analyzed a cohort of 14 cases-11 biopsy and 3 radical prostatectomy specimens-with a Gleason score of 3 + 5 = 8 or 5 + 3 = 8 present in the same biopsy or in a single dominant tumor nodule at radical prostatectomy. Clonal and subclonal relationships between GP3 and GP5 lesions were assessed using genetically validated immunohistochemical assays for ERG, PTEN, and P53. 9/14 (64%) cases showed ERG reactivity in both GP3 and GP5 lesions. Only 1/14 (7%) cases showed a discordant pattern with ERG staining present only in GP3. PTEN expression was lost in 2/14 (14%) cases with perfect concordance between GP5 and GP3. P53 nuclear reactivity was present in 1/14 (7%) case in both GP5 and GP3. This study provides first evidence that the majority of adjacent GP3 and GP5 lesions share driver alterations and are clonally related. In addition, we observed a lower-than-expected rate of PTEN loss in GP5 in the context of Gleason score 3 + 5 = 8 or 5 + 3 = 8 tumors., (Copyright © 2022. Published by Elsevier Inc.)

Analysis of DNA methylation is a valuable tool to understand disease progression and is increasingly being used to create diagnostic and prognostic clinical biomarkers. While conversion of cytosine to 5-methylcytosine (5mC) commonly results in transcriptional repression, further conversion to 5-hydroxymethylcytosine (5hmC) is associated with transcriptional activation. Here we perform the first study integrating whole-genome 5hmC with DNA, 5mC, and transcriptome sequencing in clinical samples of benign, localized, and advanced prostate cancer. 5hmC is shown to mark activation of cancer drivers and downstream targets. Furthermore, 5hmC sequencing revealed profoundly altered cell states throughout the disease course, characterized by increased proliferation, oncogenic signaling, dedifferentiation, and lineage plasticity to neuroendocrine and gastrointestinal lineages. Finally, 5hmC sequencing of cell-free DNA from patients with metastatic disease proved useful as a prognostic biomarker able to identify an aggressive subtype of prostate cancer using the genes TOP2A and EZH2, previously only detectable by transcriptomic analysis of solid tumor biopsies. Overall, these findings reveal that 5hmC marks epigenomic activation in prostate cancer and identify hallmarks of prostate cancer progression with potential as biomarkers of aggressive disease., Significance: In prostate cancer, 5-hydroxymethylcytosine delineates oncogene activation and stage-specific cell states and can be analyzed in liquid biopsies to detect cancer phenotypes. See related article by Wu and Attard, p. 3880., (©2022 The Authors; Published by the American Association for Cancer Research.)

Temporally regulated alternative splicing choices are vital for proper development, yet the wrong splice choice may be detrimental. Here, we highlight a previously unidentified role for the neurotrophin receptor splice variant TrkB.T1 in neurodevelopment, embryogenesis, transformation, and oncogenesis across multiple tumor types in humans and mice. TrkB.T1 is the predominant NTRK2 isoform across embryonic organogenesis, and forced overexpression of this embryonic pattern causes multiple solid and nonsolid tumors in mice in the context of tumor suppressor loss. TrkB.T1 also emerges as the predominant NTRK isoform expressed in a wide range of adult and pediatric tumors, including those harboring tropomyosin receptor kinase fusions. Affinity purification-mass spectrometry proteomic analysis reveals distinct interactors with known developmental and oncogenic signaling pathways such as Wnt, transforming growth factor-β, Sonic Hedgehog, and Ras. From alterations in splicing factors to changes in gene expression, the discovery of isoform specific oncogenes with embryonic ancestry has the potential to shape the way we think about developmental systems and oncology.

The androgen receptor (AR) signaling inhibitor enzalutamide (enza) is one of the principal treatments for metastatic castration-resistant prostate cancer (CRPC). Several emergent enza clinical resistance mechanisms have been described, including lineage plasticity in which the tumors manifest reduced dependency on the AR. To improve our understanding of enza resistance, herein we analyze the transcriptomes of matched biopsies from men with metastatic CRPC obtained prior to treatment and at progression (n = 21). RNA-sequencing analysis demonstrates that enza does not induce marked, sustained changes in the tumor transcriptome in most patients. However, three patients' progression biopsies show evidence of lineage plasticity. The transcription factor E2F1 and pathways linked to tumor stemness are highly activated in baseline biopsies from patients whose tumors undergo lineage plasticity. We find a gene signature enriched in these baseline biopsies that is strongly associated with poor survival in independent patient cohorts and with risk of castration-induced lineage plasticity in patient-derived xenograft models, suggesting that tumors harboring this gene expression program may be at particular risk for resistance mediated by lineage plasticity and poor outcomes., (© 2022. The Author(s).)

Downregulation of HLA class I (HLA-I) impairs immune recognition and surveillance in prostate cancer and may underlie the ineffectiveness of checkpoint blockade. However, the molecular mechanisms regulating HLA-I loss in prostate cancer have not been fully explored. Here, we conducted a comprehensive analysis of HLA-I genomic, epigenomic and gene expression alterations in primary and metastatic human prostate cancer. Loss of HLA-I gene expression was associated with repressive chromatin states including DNA methylation, histone H3 tri-methylation at lysine 27, and reduced chromatin accessibility. Pharmacological DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibition decreased DNA methylation and increased H3 lysine 27 acetylation and resulted in re-expression of HLA-I on the surface of tumor cells. Re-expression of HLA-I on LNCaP cells by DNMT and HDAC inhibition increased activation of co-cultured prostate specific membrane antigen (PSMA) 27-38 -specific CD8 + T-cells. HLA-I expression is epigenetically regulated by functionally reversible DNA methylation and chromatin modifications in human prostate cancer. Methylated HLA-I was detected in HLA-I low circulating tumor cells (CTCs), which may serve as a minimally invasive biomarker for identifying patients who would benefit from epigenetic targeted therapies., (© 2022. The Author(s).)

Purpose: Therapies targeting the androgen receptor (AR) have improved the outcome for patients with castration-sensitive prostate cancer (CSPC). Expression of the constitutively active AR splice variant-7 (AR-V7) has shown clinical utility as a predictive biomarker of AR-targeted therapy resistance in castration-resistant prostate cancer (CRPC), but its importance in CSPC remains understudied., Experimental Design: We assessed different approaches to quantify AR-V7 mRNA and protein in prostate cancer cell lines, patient-derived xenograft (PDX) models, publicly available cohorts, and independent institutional clinical cohorts, to identify reliable approaches for detecting AR-V7 mRNA and protein and its association with clinical outcome., Results: In CSPC and CRPC cohorts, AR-V7 mRNA was much less abundant when detected using reads across splice boundaries than when considering isoform-specific exonic reads. The RM7 AR-V7 antibody had increased sensitivity and specificity for AR-V7 protein detection by immunohistochemistry (IHC) in CRPC cohorts but rarely identified AR-V7 protein reactivity in CSPC cohorts, when compared with the EPR15656 AR-V7 antibody. Using multiple CRPC PDX models, we demonstrated that AR-V7 expression was exquisitely sensitive to hormonal manipulation. In CSPC institutional cohorts, AR-V7 protein quantification by either assay was associated neither with time to development of castration resistance nor with overall survival, and intense neoadjuvant androgen-deprivation therapy did not lead to significant AR-V7 mRNA or staining following treatment. Neither pre- nor posttreatment AR-V7 levels were associated with volumes of residual disease after therapy., Conclusions: This study demonstrates that further analytical validation and clinical qualification are required before AR-V7 can be considered for clinical use in CSPC as a predictive biomarker., (©2022 The Authors; Published by the American Association for Cancer Research.)

Imaging specialists must recognize potential mimics of prostate cancer (PCa) on multi-parametric magnetic resonance imaging (mpMRI). We describe the appearance of diffuse adenosis of the peripheral zone (DAPZ) on mpMRI. The features of DAPZ parallel those of diffuse PCa, with low signal on T2-weighted images, rapid enhancement on dynamic contrast-enhanced sequences, and restricted diffusion. DAPZ is typically encountered in younger men with elevated prostate specific antigen (PSA) levels and portends an increased risk of the development of PCa. Recognition of the imaging appearance of DAPZ may reassure patients with concordant pathologic findings and may aid in selecting patients for follow-up., Competing Interests: None., (© 2022 The Authors.)

Purpose: To determine whether metastatic castration-resistant prostate cancers (mCRPC) partition into molecular phenotypes corresponding to intrinsic differentiation states and ascertain whether these subtypes exhibit specific druggable features and associate with treatment outcomes., Experimental Design: We used RNAseq, digital spatial profiling, and histological assessments from metastatic biopsies and patient-derived xenografts to segregate mCRPCs into subtypes defined by the PAM50 breast cancer classification algorithm. Subtype associations with treatment responses in preclinical models and patients were determined., Results: Using the PAM50 algorithm, we partitioned 270 mCRPC tumors into LumA (42%), LumB (24%), and Basal (34%) subtypes with classification largely driven by proliferation rates and androgen receptor (AR) activity. Most neuroendocrine tumors classified as Basal. Pathways enriched in the LumA subtype include TGFß and NOTCH signaling. LumB subtype tumors were notable for elevated MYC activity. Basal subtype tumors exhibited elevated IL6-STAT3 signaling and features of adult stem cell states. In patients where multiple tumors were evaluated, the majority had concordant PAM50 subtype determination, though a subset exhibited marked inter- and intratumor heterogeneity, including divergent classifications between primary and metastatic sites. In preclinical models, LumA subtype tumors were highly responsive to androgen deprivation and docetaxel chemotherapy whereas Basal tumors were largely resistant. In clinical cohorts patients with Basal subtype tumors demonstrated a shorter time on treatment with AR signaling inhibitors and docetaxel relative to patients with luminal subtypes., Conclusions: Subtyping of mCRPC based on cell differentiation states has potential clinical utility for identifying patients with divergent expression of treatment targets and responses to systemic therapy., (©2022 The Authors; Published by the American Association for Cancer Research.)

A limited number of cell lines have fueled the majority of preclinical prostate cancer research, but their genomes remain incompletely characterized. Here, we utilized whole-genome linked-read sequencing for comprehensive characterization of phased mutations and rearrangements in the most commonly used cell lines in prostate cancer research including PC3, LNCaP, DU145, CWR22Rv1, VCaP, LAPC4, MDA-PCa-2b, RWPE-1, and four derivative castrate-resistant (CR) cell lines LNCaP_Abl, LNCaP_C42b, VCaP-CR, and LAPC4-CR. Phasing of mutations allowed determination of "gene-level haplotype" to assess whether genes harbored heterozygous mutations in one or both alleles. Phased structural variant analysis allowed identification of complex rearrangement chains consistent with chromothripsis and chromoplexy. In addition, comparison of parental and derivative CR lines revealed previously known and novel genomic alterations associated with the CR phenotype., Implications: This study therefore comprehensively characterized phased genomic alterations in the commonly used prostate cancer cell lines, providing a useful resource for future prostate cancer research., (©2022 The Authors; Published by the American Association for Cancer Research.)