Challenges in recognizing treatment-related neuroendocrine prostate cancer

The Use of Lurbinectedin for the Treatment of Small Cell and Neuroendocrine Carcinoma of the Prostate

INTRODUCTION

Lurbinectedin is FDA approved for treatment of metastatic small cell lung cancer (SCLC) following progression on or after platinum-based chemotherapy. Prostatic small cell or neuroendocrine carcinoma (SC/NEPC) behaves like SCLC; however, no safety or efficacy data for lurbinectedin in SC/NEPC exists.

PATIENTS AND METHODS

All SC/NEPC patients treated with lurbinectedin across 4 academic oncology centers were identified. Baseline patient data and lurbinectedin outcomes including radiographic responses (complete response [CR], partial response [PR], stable disease [SD], progressive disease [PD]), progression free survival (PFS), overall survival (OS), and treatment-related adverse events (trAEs) were described. Clinical benefit rate (CBR) included CR, PR, or SD on imaging. Descriptive statistics were performed.

RESULTS

At first lurbinectedin dose, all 18 patients had metastatic disease. Median age was 63.5 (Range: 53-84), number of prior systemic therapies was 4 (Range: 2-7), and lurbinectedin cycles completed was 5 (Range: 1-10). ADT was administered during lurbinectedin treatment in 9/18 patients. CBR was 9/16 (56%). The most common trAEs were fatigue and anemia. Median OS and PFS were 6.01 (0.23-16.69) and 3.35 (0.16-7.79) months.

CONCLUSIONS

Lurbinectedin showed modest but significant clinical benefit in some patients with SC/NEPC and demonstrated an acceptable toxicity profile with no hospitalizations from trAEs. SC/NEPC is an aggressive disease with a poor prognosis for which more treatment options are needed. Evidence for subsequent treatments after platinum-based chemotherapy is lacking. Lurbinectedin is an active treatment option for SC/NEPC; however, larger confirmatory studies are needed.

PROX1 drives neuroendocrine plasticity and liver metastases in prostate cancer

With the widespread use of anti-androgen therapy, such as abiraterone and enzalutamide, the incidence of neuroendocrine prostate cancer (NEPC) is increasing. NEPC is a lethal form of prostate cancer (PCa), with a median overall survival of less than one year after diagnosis. In addition to the common bone metastases seen in PCa, NEPC exhibits characteristics of visceral metastases, notably liver metastasis, which serves as an indicator of a poor prognosis clinically. Key factors driving the neuroendocrine plasticity of PCa have been identified, yet the underlying mechanism behind liver metastasis remains unclear. In this study, we identified PROX1 as a driver of neuroendocrine plasticity in PCa, responsible for promoting liver metastases. Mechanistically, anti-androgen therapy alleviates transcriptional inhibition of PROX1. Subsequently, elevated PROX1 levels drive both neuroendocrine plasticity and liver-specific transcriptional reprogramming, promoting liver metastases. Moreover, liver metastases in PCa induced by PROX1 depend on reprogrammed lipid metabolism, a disruption that effectively reduces the formation of liver metastases.

Androgen deprivation induces neuroendocrine phenotypes in prostate cancer cells through CREB1/EZH2-mediated downregulation of REST

Although effective initially, prolonged androgen deprivation therapy (ADT) promotes neuroendocrine differentiation (NED) and prostate cancer (PCa) progression. It is incompletely understood how ADT transcriptionally induces NE genes in PCa cells. CREB1 and REST are known to positively and negatively regulate neuronal gene expression in the brain, respectively. No direct link between these two master neuronal regulators has been elucidated in the NED of PCa. We show that REST mRNA is downregulated in NEPC cell and mouse models, as well as in patient samples. Phenotypically, REST overexpression increases ADT sensitivity, represses NE genes, inhibits colony formation in culture, and xenograft tumor growth of PCa cells. As expected, ADT downregulates REST in PCa cells in culture and in mouse xenografts. Interestingly, CREB1 signaling represses REST expression. In studying the largely unclear mechanism underlying transcriptional repression of REST by ADT, we found that REST is a direct target of EZH2 epigenetic repression. Finally, genetic rescue experiments demonstrated that ADT induces NED through EZH2's repression of REST, which is enhanced by ADT-activated CREB1 signaling. In summary, our study has revealed a key pathway underlying NE gene upregulation by ADT, as well as established novel relationships between CREB1 and REST, and between EZH2 and REST, which may also have implications in other cancer types and in neurobiology.

Systemic metastases in large cell neuroendocrine prostate cancer: a rare case report and literature review

Neuroendocrine prostate neoplasms, encompassing small cell carcinoma, carcinoid, and large cell carcinoma, are infrequently observed in malignant prostate tumors. The occurrence of large cell neuroendocrine prostate cancer (LCNEPC) is exceedingly rare. In this study, the patient initially presented with a persistent dysuria for a duration of one year, accompanied by a serum prostate-specific antigen (PSA) level of 17.83ng/mL. Prostate magnetic resonance imaging (MRI) and chest computed tomography (CT) scan showed that a neoplastic lesion was considered, and prostate biopsy confirmed prostate adenocarcinoma with a Gleason score of 7 (4 + 3). Then, thoracoscopic lung tumor resection was performed, and the pathological examination revealed the presence of primary moderately differentiated invasive adenocarcinoma of the lung and metastatic prostate adenocarcinoma, the Gleason score was 8 (4 + 4). After 1 year of endocrine therapy with goserelin acetate and bicalutamide, he underwent a laparoscopic radical prostatectomy (LRP), the pathological report indicated the presence of adenocarcinoma mixed with NE carcinoma. Two months after the LRP, the patient experienced gross hematuria and sacral tail pain. Further examination revealed multiple metastatic lesions throughout the body. He also underwent transurethral resection of bladder tumor (TURBT) for bladder tumor and received etoposide+ cisplatin chemotherapy three weeks post-surgery. The patient eventually died of multi-organ failure due to myelosuppression after chemotherapy. This case report presents an uncommon instance of LCNEPC with widespread systemic metastases, while also providing a comprehensive review of existing literature to facilitate improved management and treatment strategies for similar patients in subsequent cases.

Prognostic nomogram to predict cancer-specific survival with small-cell carcinoma of the prostate: a multi-institutional study

Objective

The aim of this study is to examine the predictive factors for cancer-specific survival (CSS) in patients diagnosed with Small-Cell Carcinoma of the Prostate (SCCP) and to construct a prognostic model.

Methods

Cases were selected using the Surveillance, Epidemiology, and End Results (SEER) database. The Kaplan-Meier method was utilized to calculate survival rates, while Lasso and Cox regression were employed to analyze prognostic factors. An independent prognostic factor-based nomogram was created to forecast CSS at 12 and 24 months. The model's predictive efficacy was assessed using the consistency index (C-index), calibration curve, and decision curve analysis (DCA) in separate tests.

Results

Following the analysis of Cox and Lasso regression, age, race, Summary stage, and chemotherapy were determined to be significant risk factors (P < 0.05). In the group of participants who received training, the rate of 12-month CSS was 44.6%, the rate of 24-month CSS was 25.5%, and the median time for CSS was 10.5 months. The C-index for the training cohort was 0.7688 ± 0.024. As for the validation cohort, it was 0.661 ± 0.041. According to the nomogram, CSS was accurately predicted and demonstrated consistent and satisfactory predictive performance at both 12 months (87.3% compared to 71.2%) and 24 months (80.4% compared to 71.7%). As shown in the external validation calibration plot, the AUC for 12- and 24-month is 64.6% vs. 56.9% and 87.0% vs. 70.7%, respectively. Based on the calibration plot of the CSS nomogram at both the 12-month and 24-month marks, it can be observed that both the actual values and the nomogram predictions indicate a predominantly stable CSS. When compared to the AJCC staging system, DCA demonstrated a higher level of accuracy in predicting CSS through the use of a nomogram.

Conclusion

Clinical prognostic factors can be utilized with nomograms to forecast CSS in Small-Cell Carcinoma of the Prostate (SCCP).

The Localized Neuroendocrine Transformation of Prostate Adenocarcinoma: A Case Report and Literature Review of Current Treatment Modalities

Most prostate cancers are adenocarcinomas. However, there is a rare and aggressive subtype known as small cell carcinoma of the prostate (SCCP). This variant of prostate cancer is marked by its distinctive features, including high-grade malignancy, neuroendocrine differentiation, and a unique clinical presentation, often involving metastases. This report details the presentation and management of a 66-year-old African-American male who was originally diagnosed with high-risk adenocarcinoma of the prostate. At initial diagnosis, the patient was suboptimally treated with radiation alone without androgen deprivation therapy (ADT). On re-biopsy several years later, he was found to have localized recurrent disease with transformation into SCCP. The prognosis for SCCP is poor with a mean survival. Patients typically present with metastases, commonly to the brain, liver, bones, or bladder. SCCP after treatment for adenocarcinoma of the prostate is more common than de novo presentation. The amount of neuroendocrine differentiation of SCCP often increases with treatment, particularly after treatment with ADT. This report emphasizes the importance of timely and optimal care when treating prostate cancer and suggests potential consequences that inappropriate treatment or treatment delays may entail.

Treatment-related neuroendocrine prostate cancer with BRCA2 germline mutation treated with olaparib

Introduction

The efficacy of olaparib for treatment-related neuroendocrine prostate cancer is unknown. Here, we report a case of treatment-related neuroendocrine prostate cancer with a BRCA2 mutation that was treated with olaparib with 1-year efficacy.

Case presentation

A 75-year-old man initially diagnosed with prostate adenocarcinoma developed treatment-related neuroendocrine prostate cancer after 10-year androgen deprivation therapy. Despite the initial temporary effects of etoposide and carboplatin, the patient experienced prostate bed tumor recurrence 1 year after chemotherapy cessation. FoundationOne® detected a BRCA2 gene mutation, and olaparib was initiated after repeating one chemotherapy course using the same chemotherapeutic agents. The patient received olaparib with sustained tumor regression for 1 year without severe side effects.

Conclusion

Olaparib may be the treatment of choice for treatment-related neuroendocrine prostate cancer in patients with BRCA mutations.

Aggressive prostatic adenocarcinoma with urothelial-like morphology, with frequent CK7/CK20/HMWK expression and occasional diffuse neuroendocrine features: A clinicopathologic study of 12 cases

INTRODUCTION

Prostatic adenocarcinoma can occasionally display urothelial carcinoma morphology, which prompts immunohistochemistry (IHC) studies to determine its lineage. Typically, prostate cancer is characterized by the lack of cytokeratin (CK) 7, CK20 and high molecular weight keratin (HMWK) expression, as opposed to bladder cancer.

METHODS

We report a series of 12 prostatic adenocarcinoma cases with unusual urothelial-like morphology, diagnosed at two academic institutions in Toronto between 2018 and 2023, and analyzed by immunohistochemistry for prostatic, urothelial, and neuroendocrine marker expression. We collected patient age, androgen deprivation therapy (ADT) status, tumour site, histomorphology, Grade group (GG) and results of genetic testing.

RESULTS

The median age of the 12 patients included in this case series was 75.5 years (range 41-85). A history of prostatic cancer was noted in 7/12 (58%) patients. Five of nine (56%) patients had elevated serum PSA level at diagnosis. Six of eleven (55%) patients had prior ADT. Tumour sites were prostate (n = 6), bladder (n = 3), liver metastases (n = 2), and lung metastasis (n = 1). GGs of the primary tumours were GG3 (n = 1) and GG5 (n = 8). The observed urothelial-like morphology was diffuse in ten cases, and focal in two cases. CK7 was strong/diffuse in 8/11 tested cases, and focal weak in one case. CK20, HMWK, p63 and GATA3 were patchy/focal/weak/moderate in 3/6, 4/7, 4/8 and 2/9 cases, respectively. Ten (83%) cases were positive for at least one prostatic marker; eight (67%) cases had loss/weak staining of at least one prostatic marker. AR loss was seen in 2/7 (29%) cases. Seven of ten (70%) cases had diffuse/strong expression of at least one neuroendocrine marker. No trend was evident between prior ADT/AR status and any IHC result. Molecular analyses for DNA damage repair (DDR) genes (n = 6) demonstrated one ATM deletion (bladder). In addition, one TMPRSS2:ERG fusion (lung metastasis) was identified.

CONCLUSION

This series comprises high-grade and/or metastatic prostatic adenocarcinoma cases with distinctive urothelial-like morphology and frequent aberrant CK7/CK20/HMWK expression. Their histomorphology, highly suggestive of an urothelial origin, represents a diagnostic pitfall that can lead to considerable management repercussions. The fact that a high proportion of the reported cases had loss/weak expression of at least one of the tested prostatic-specific markers, and occasionally a diffuse positivity for neuroendocrine markers highlights the importance of (1) clinical history and (2) utilization of broad IHC panels to correctly diagnose such unusual prostate cancer cases.

DPYSL5 is highly expressed in treatment-induced neuroendocrine prostate cancer and promotes lineage plasticity via EZH2/PRC2

Treatment-induced neuroendocrine prostate cancer (t-NEPC) is a lethal subtype of castration-resistant prostate cancer resistant to androgen receptor (AR) inhibitors. Our study unveils that AR suppresses the neuronal development protein dihydropyrimidinase-related protein 5 (DPYSL5), providing a mechanism for neuroendocrine transformation under androgen deprivation therapy. Our unique CRPC-NEPC cohort, comprising 135 patient tumor samples, including 55 t-NEPC patient samples, exhibits a high expression of DPYSL5 in t-NEPC patient tumors. DPYSL5 correlates with neuroendocrine-related markers and inversely with AR and PSA. DPYSL5 overexpression in prostate cancer cells induces a neuron-like phenotype, enhances invasion, proliferation, and upregulates stemness and neuroendocrine-related markers. Mechanistically, DPYSL5 promotes prostate cancer cell plasticity via EZH2-mediated PRC2 activation. Depletion of DPYSL5 decreases proliferation, induces G1 phase cell cycle arrest, reverses neuroendocrine phenotype, and upregulates luminal genes. In conclusion, DPYSL5 plays a critical role in regulating prostate cancer cell plasticity, and we propose the AR/DPYSL5/EZH2/PRC2 axis as a driver of t-NEPC progression.

Fascin-1 expression is associated with neuroendocrine prostate cancer and directly suppressed by androgen receptor

BACKGROUND

Neuroendocrine prostate cancer (NEPC) is an aggressive form of prostate cancer, arising from resistance to androgen-deprivation therapies. However, the molecular mechanisms associated with NEPC development and invasiveness are still poorly understood. Here we investigated the expression and functional significance of Fascin-1 (FSCN1), a pro-metastasis actin-bundling protein associated with poor prognosis of several cancers, in neuroendocrine differentiation of prostate cancer.

METHODS

Differential expression analyses using Genome Expression Omnibus (GEO) database, clinical samples and cell lines were performed. Androgen or antagonist's cellular treatments and knockdown experiments were used to detect changes in cell morphology, molecular markers, migration properties and in vivo tumour growth. Chromatin immunoprecipitation-sequencing (ChIP-Seq) data and ChIP assays were analysed to decipher androgen receptor (AR) binding.

RESULTS

We demonstrated that FSCN1 is upregulated during neuroendocrine differentiation of prostate cancer in vitro, leading to phenotypic changes and NEPC marker expression. In human prostate cancer samples, FSCN1 expression is restricted to NEPC tumours. We showed that the androgen-activated AR downregulates FSCN1 expression and works as a transcriptional repressor to directly suppress FSCN1 expression. AR antagonists alleviate this repression. In addition, FSCN1 silencing further impairs in vivo tumour growth.

CONCLUSION

Collectively, our findings identify FSCN1 as an AR-repressed gene. Particularly, it is involved in NEPC aggressiveness. Our results provide the rationale for the future clinical development of FSCN1 inhibitors in NEPC patients.

Androgen deprivation induces neuroendocrine phenotypes in prostate cancer cells through CREB1/EZH2-mediated downregulation of REST

Although effective initially, prolonged androgen deprivation therapy (ADT) promotes neuroendocrine differentiation (NED) and prostate cancer (PCa) progression. It is incompletely understood how ADT transcriptionally induces NE genes in PCa cells. CREB1 and REST are known to positively and negatively regulate neuronal gene expression in the brain, respectively. No direct link between these two master neuronal regulators has been elucidated in the NED of PCa. We show that REST mRNA is downregulated in NEPC cell and mouse models, as well as in patient samples. Phenotypically, REST overexpression increases ADT sensitivity, represses NE genes, inhibits colony formation in culture, and xenograft tumor growth of PCa cells. As expected, ADT downregulates REST in PCa cells in culture and in mouse xenografts. Interestingly, CREB1 signaling represses REST expression. In studying the largely unclear mechanism underlying transcriptional repression of REST by ADT, we found that REST is a direct target of EZH2 epigenetic repression. Finally, genetic rescue experiments demonstrated that ADT induces NED through EZH2's repression of REST, which is enhanced by ADT-activated CREB signaling. In summary, our study has revealed a key pathway underlying NE gene upregulation by ADT, as well as established novel relationships between CREB1 and REST, and between EZH2 and REST, which may also have implications in other cancer types and in neurobiology.

Targeting the Androgen Signaling Axis in Prostate Cancer

Activation of the androgen receptor (AR) and AR-driven transcriptional programs is central to the pathophysiology of prostate cancer. Despite successful translational efforts in targeting AR, therapeutic resistance often occurs as a result of molecular alterations in the androgen signaling axis. The efficacy of next-generation AR-directed therapies for castration-resistant prostate cancer has provided crucial clinical validation for the continued dependence on AR signaling and introduced a range of new treatment options for men with both castration-resistant and castration-sensitive disease. Despite this, however, metastatic prostate cancer largely remains an incurable disease, highlighting the need to better understand the diverse mechanisms by which tumors thwart AR-directed therapies, which may inform new therapeutic avenues. In this review, we revisit concepts in AR signaling and current understandings of AR signaling-dependent resistance mechanisms as well as the next frontier of AR targeting in prostate cancer.

Reporting Trends, Practices, and Resource Utilization in Neuroendocrine Tumors of the Prostate Gland: A Survey among Thirty-Nine Genitourinary Pathologists

Background. Neuroendocrine differentiation in the prostate gland ranges from clinically insignificant neuroendocrine differentiation detected with markers in an otherwise conventional prostatic adenocarcinoma to a lethal high-grade small/large cell neuroendocrine carcinoma. The concept of neuroendocrine differentiation in prostatic adenocarcinoma has gained considerable importance due to its prognostic and therapeutic ramifications and pathologists play a pivotal role in its recognition. However, its awareness, reporting, and resource utilization practice patterns among pathologists are largely unknown. Methods. Representative examples of different spectrums of neuroendocrine differentiation along with a detailed questionnaire were shared among 39 urologic pathologists using the survey monkey software. Participants were specifically questioned about the use and awareness of the 2016 WHO classification of neuroendocrine tumors of the prostate, understanding of the clinical significance of each entity, and use of different immunohistochemical (IHC) markers. De-identified respondent data were analyzed. Results. A vast majority (90%) of the participants utilize IHC markers to confirm the diagnosis of small cell neuroendocrine carcinoma. A majority (87%) of the respondents were in agreement regarding the utilization of type of IHC markers for small cell neuroendocrine carcinoma for which 85% of the pathologists agreed that determination of the site of origin of a high-grade neuroendocrine carcinoma is not critical, as these are treated similarly. In the setting of mixed carcinomas, 62% of respondents indicated that they provide quantification and grading of the acinar component. There were varied responses regarding the prognostic implication of focal neuroendocrine cells in an otherwise conventional acinar adenocarcinoma and for Paneth cell-like differentiation. The classification of large cell neuroendocrine carcinoma was highly varied, with only 38% agreement in the illustrated case. Finally, despite the recommendation not to perform neuroendocrine markers in the absence of morphologic evidence of neuroendocrine differentiation, 62% would routinely utilize IHC in the work-up of a Gleason score 5 + 5 = 10 acinar adenocarcinoma and its differentiation from high-grade neuroendocrine carcinoma. Conclusion. There is a disparity in the practice utilization patterns among the urologic pathologists with regard to diagnosing high-grade neuroendocrine carcinoma and in understanding the clinical significance of focal neuroendocrine cells in an otherwise conventional acinar adenocarcinoma and Paneth cell-like neuroendocrine differentiation. There seems to have a trend towards overutilization of IHC to determine neuroendocrine differentiation in the absence of neuroendocrine features on morphology. The survey results suggest a need for further refinement and development of standardized guidelines for the classification and reporting of neuroendocrine differentiation in the prostate gland.

A novel GRK3-HDAC2 regulatory pathway is a key direct link between neuroendocrine differentiation and angiogenesis in prostate cancer progression

The mechanisms underlying the progression of prostate cancer (PCa) to neuroendocrine prostate cancer (NEPC), an aggressive PCa variant, are largely unclear. Two prominent NEPC phenotypes are elevated NE marker expression and heightened angiogenesis. Identifying the still elusive direct molecular links connecting angiogenesis and neuroendocrine differentiation (NED) is crucial for our understanding and targeting of NEPC. Here we found that histone deacetylase 2 (HDAC2), whose role in NEPC has not been reported, is one of the most upregulated epigenetic regulators in NEPC. HDAC2 promotes both NED and angiogenesis. G protein-coupled receptor kinase 3 (GRK3), also upregulated in NEPC, is a critical promoter for both phenotypes too. Of note, GRK3 phosphorylates HDAC2 at S394, which enhances HDAC2's epigenetic repression of potent anti-angiogenic factor Thrombospondin 1 (TSP1) and master NE-repressor RE1 Silencing Transcription Factor (REST). Intriguingly, REST suppresses angiogenesis while TSP1 suppresses NE marker expression in PCa cells, indicative of their novel functions and their synergy in cross-repressing the two phenotypes. Furthermore, the GRK3-HDAC2 pathway is activated by androgen deprivation therapy and hypoxia, both known to promote NED and angiogenesis in PCa. These results indicate that NED and angiogenesis converge on GRK3-enhanced HDAC2 suppression of REST and TSP1, which constitutes a key missing link between two prominent phenotypes of NEPC.

Qingdai Decoction suppresses prostate cancer growth in lethal-stage prostate cancer models

ETHNOPHARMACOLOGICAL RELEVANCE

Contemporary therapy for advanced castration-resistant prostate cancer (CRPC) employs reagents such as enzalutamide and abiraterone acetate targeting the androgen receptor (AR) transcription axis only provide a temporary response and rapidly develop resistance. Additionally, neuroendocrine prostate cancer (NEPC) is an AR pathway-independent and lethal-stage prostate cancer with no standard therapy. Qingdai Decoction (QDT), a traditional Chinese medicine formula, has various pharmacological activities and was widely used for the treatment of different diseases including prostatitis which may contribute to prostate cancer development.

AIM OF THE STUDY

This study aims to explore the anti-tumor role and potential mechanism of QDT on prostate cancer.

MATERIAL AND METHODS

CRPC prostate cancer cell models and xenograft mice models were established for research. The effect of TCMs on cancer growth and metastasis were determined by CCK-8, wound-healing assays and the PC3-xenografted mice model. The toxicity of QDT in the major organs was investigated by H&E staining. The compound-target network was analyzed with network pharmacology. The correlation of QDT targets with prostate cancer patient's prognosis was analyzed with multiple prostate cancer patient cohorts. The expression of related proteins and mRNA were detected by western blot and real-time PCR. The gene knockdown was achieved with CRISPR-Cas13 technology.

RESULTS

By integrating functional screening, network pharmacology analysis, CRISPR-Cas13 directed RNA targeting, and molecular biology validation in different prostate cancer models and clinical prostate cancer cohorts, we found that Qingdai Decoction (QDT), a Traditional Chinese Medicine, can repress cancer growth in advanced prostate cancer models in vitro and in vivo in an AR independent manner by targeting NOS3, TGFB1, and NCOA2.

CONCLUSION

This study not only identified QDT as a novel drug for lethal-stage prostate cancer treatment but also provided an extensive Integrative research paradigm for investigating the roles and mechanisms of TCMs for the treatment of other diseases.

PSMA PET/CT: joint EANM procedure guideline/SNMMI procedure standard for prostate cancer imaging 2.0

Here we aim to provide updated guidance and standards for the indication, acquisition, and interpretation of PSMA PET/CT for prostate cancer imaging. Procedures and characteristics are reported for a variety of available PSMA small radioligands. Different scenarios for the clinical use of PSMA-ligand PET/CT are discussed. This document provides clinicians and technicians with the best available evidence, to support the implementation of PSMA PET/CT imaging in research and routine practice.

Trigred motif 36 regulates neuroendocrine differentiation of prostate cancer via HK2 ubiquitination and GPx4 deficiency

Neuroendocrine prostate cancer (NEPC), the most lethal subtype of castration-resistant prostate cancer (PCa), may evolve from the neuroendocrine differentiation (NED) of PCa cells. However, the molecular mechanism that triggers NED is unknown. Trigred motif 36 (TRIM36), a member of the TRIM protein family, exhibits oncogenic or anti-oncogenic roles in various cancers. We have previously reported that TRIM36 is highly expressed to inhibit the invasion and proliferation of PCa. In the present study, we first found that TRIM36 was lowly expressed in NEPC and its overexpression suppressed the NED of PCa. Next, based on proteomic analysis, we found that TRIM36 inhibited the glycolysis pathway through suppressing hexokinase 2 (HK2), a crucial glycolytic enzyme catalyzing the conversion of glucose to glucose-6-phosphate. TRIM36 specifically bound to HK2 through lysine 48 (lys48)-mediated ubiquitination of HK2. Moreover, TRIM36-mediated ubiquitination degradation of HK2 downregulated the level of glutathione peroxidase 4 (GPx4), a process that contributed to ferroptosis. In conclusion, TRIM36 can inhibit glycolysis via lys48-mediated HK2 ubiquitination to reduce GPX4 expression and activate ferroptosis, thereby inhibiting the NED in PCa. Targeting TRIM36 might be a promising approach to retard NED and treat NEPC.

Identification of molecular subtypes and a prognostic signature based on chromatin regulators related genes in prostate cancer

The clinical and molecular phenotypes of prostate cancer (PCa) exhibit substantial heterogeneity, ranging from indolent to metastatic disease. In this study, we aimed to identify PCa subtypes and construct a gene signature that can predict the recurrence-free survival (RFS) of PCa patients based on chromatin regulators genes (CRGs). Strikingly, we identified two heterogeneous subtypes with distinct clinical and molecular characteristics. Furthermore, by performing differential analysis between the two CRGs subtypes, we successfully constructed a gene signature to predict PCa prognosis. The signature, comprising four genes (MXD3, SSTR1, AMH and PPFIA2), was utilized to classify PCa patients into two risk groups; the high-risk group was characterized by poor prognosis and more aggressive clinical features. Moreover, we investigated the immune profile, mutation landscape and molecular pathways in each of the groups. Additionally, drug-susceptibility testing was performed to explore sensitive drugs for high-risk patients. Furthermore, we found that MXD3 downregulation suppressed the proliferation of PCa cell lines in vitro. Overall, our results highlight the signature based on CRGs as a powerful tool for predicting RFS of PCa patients, as well as an indicator for personalized treatment of those patients.

Ectopic adrenocorticotrophic hormone syndrome secondary to treatment-related neuroendocrine differentiation of metastatic castrate-resistant prostate cancer

Summary

A 64-year-old man with progressive metastatic castrate-resistant prostate adenocarcinoma presented with recurrent fluid overload, severe hypokalaemia with metabolic alkalosis and loss of glycaemic control. Clinical features were facial plethora, skin bruising and proximal myopathy. Plasma adrenocorticotrophic hormone (ACTH), serum cortisol and 24-h urinary cortisol levels were elevated. Low-dose dexamethasone failed to suppress cortisol. Pituitary MRI was normal and 68Gallium-DOTATATE PET-CT scan showed only features of metastatic prostate cancer. He was diagnosed with ectopic ACTH syndrome secondary to treatment-related neuroendocrine prostate cancer differentiation. Medical management was limited by clinical deterioration, accessibility of medications and cancer progression. Ketoconazole and cabergoline were utilised, but cortisol remained uncontrolled. He succumbed 5 months following diagnosis. Treatment-related neuroendocrine differentiation of prostate adenocarcinoma is a rare cause of ectopic ACTH syndrome.

Learning points

Neuroendocrine differentiation following prostate adenocarcinoma treatment with androgen deprivation has been described. Ectopic adrenocorticotrophic hormone (ACTH) syndrome should be considered where patients with metastatic prostate cancer develop acute electrolyte disturbance or fluid overload. Ketoconazole interferes with adrenal and gonadal steroidogenesis and can be used in ectopic ACTH syndrome, but the impact may be insufficient. Inhibition of gonadal steroidogenesis is favourable in prostate cancer. More data are required to evaluate the use of cabergoline in ectopic ACTH syndrome. Ectopic ACTH syndrome requires prompt management and is challenging in the face of metastatic cancer.

Clinicopathological and immunological profiles of prostate adenocarcinoma and neuroendocrine prostate cancer

BACKGROUND

Biomarkers of DNA damage repair deficiency provide opportunities for personalized treatment with immunotherapy. However, there is limited research on the immune microenvironment of adeno-neuroendocrine prostate cancer (NEPC). In this study, we aimed to assess and describe the comprehensive clinicopathological manifestations of NEPC to improve diagnosis and predict prognosis.

METHODS

A retrospective medical record review of 66 patients with prostate cancer (PCa) was performed. PCa samples from the 66 patients were analyzed using immunohistochemical staining for the detection of chromogranin, neural cell adhesion molecule 1, and synaptophysin. For tumor-associated immune microenvironment analysis, PD-L1, CD3, and CD8 were labeled in tissue slides. The effect of clinicopathological factors on the survival of patients with Adeno-NEPC was analyzed.

RESULTS

Twenty patients presented with adeno-NEPC, whereas 46 presented with adeno-PCa. The median age of patients at PCa diagnosis was 67.86 ± 7.05 years (68.65 ± 7.23 years, adeno-NEPC; 67.52 ± 7.02 years, adeno-PCa). Eleven patients with adeno-NEPC underwent prostatectomy, whereas nine received primary androgen deprivation therapy (ADT). Additionally, 30 patients with adeno-PCa underwent prostatectomy, whereas 16 (34.8%) received primary ADT. There was a significant difference in overall survival between patients with adeno-NEPC and those with adeno-PCa (46.0 months vs. 65.0 months). There was also a significant difference in time from prostatectomy to biochemical recurrence between the groups of patients who underwent prostatectomy. Prostatectomy and normal lactate dehydrogenase levels were clinical factors that were significantly associated with better outcomes in patients with adeno-NEPC. Metastatic adeno-NEPC was associated with a higher programmed death ligand 1 (PD-L1) score (2-4) than localized PCa. The data showed that PD-L1 expression in adeno-NEPC may be negatively associated with that in CD8⁺ T cells.

CONCLUSIONS

Our study revealed clinicopathological manifestations of adeno-NEPC and some possible predictive factors significantly associated with better outcomes in patients with adeno-NEPC. These findings might be beneficial in the development of diagnostic strategies and customized treatment plans.

Expanding the prostate cancer cell line repertoire with ACRJ-PC28, an AR-negative neuroendocrine cell line derived from an African-Caribbean patient

Prostate cell lines from diverse backgrounds are important to addressing disparities in prostate cancer (PCa) incidence and mortality rates among Black men. ACRJ-PC28 was developed from a transrectal needle biopsy and established via inactivation of the CDKN2A locus and simultaneous expression of human telomerase. Characterization assays included growth curve analysis, immunoblots, IHC, 3D cultures, immunofluorescence imaging, confocal microscopy, flow cytometry, WGS, and RNA-Seq. ACRJ-PC28 has been passaged more than 40 times in vitro over 10 months with a doubling time of 45 hours. STR profiling confirmed the novelty and human origin of the cell line. RNA-Seq confirmed the expression of prostate specific genes alpha-methylacyl-CoA racemase (AMACR) and NKX3.1 and Neuroendocrine specific markers synaptophysin (SYP) and enolase 2 (ENO2) and IHC confirmed the presence of AMACR. Immunoblots indicated the cell line is of basal-luminal type; expresses p53 and pRB and is AR negative. WGS confirmed the absence of exonic mutations and the presence of intronic variants that appear to not affect function of AR, p53, and pRB. RNA-Seq data revealed numerous TP53 and RB1 mRNA splice variants and the lack of AR mRNA expression. This is consistent with retention of p53 function in response to DNA damage and pRB function in response to contact inhibition. Soft agar anchorage-independent analysis indicated that the cells are transformed, confirmed by principal component analysis (PCA) where ACRJ-PC28 cells cluster alongside other PCa tumor tissues, yet was distinct. The novel methodology described should advance prostate cell line development, addressing the disparity in PCa among Black men.

Druggable Metabolic Vulnerabilities Are Exposed and Masked during Progression to Castration Resistant Prostate Cancer

There is an urgent need for exploring new actionable targets other than androgen receptor to improve outcome from lethal castration-resistant prostate cancer. Tumor metabolism has reemerged as a hallmark of cancer that drives and supports oncogenesis. In this regard, it is important to understand the relationship between distinctive metabolic features, androgen receptor signaling, genetic drivers in prostate cancer, and the tumor microenvironment (symbiotic and competitive metabolic interactions) to identify metabolic vulnerabilities. We explore the links between metabolism and gene regulation, and thus the unique metabolic signatures that define the malignant phenotypes at given stages of prostate tumor progression. We also provide an overview of current metabolism-based pharmacological strategies to be developed or repurposed for metabolism-based therapeutics for castration-resistant prostate cancer.

Agent-Based Models Help Interpret Patterns of Clinical Drug Resistance by Contextualizing Competition Between Distinct Drug Failure Modes

Introduction

Modern targeted cancer therapies are carefully crafted small molecules. These exquisite technologies exhibit an astonishing diversity of observed failure modes (drug resistance mechanisms) in the clinic. This diversity is surprising because back of the envelope calculations and classic modeling results in evolutionary dynamics suggest that the diversity in the modes of clinical drug resistance should be considerably smaller than what is observed. These same calculations suggest that the outgrowth of strong pre-existing genetic resistance mutations within a tumor should be ubiquitous. Yet, clinically relevant drug resistance occurs in the absence of obvious resistance conferring genetic alterations. Quantitatively, understanding the underlying biological mechanisms of failure mode diversity may improve the next generation of targeted anticancer therapies. It also provides insights into how intratumoral heterogeneity might shape interpatient diversity during clinical relapse.

Materials and Methods

We employed spatial agent-based models to explore regimes where spatial constraints enable wild type cells (that encounter beneficial microenvironments) to compete against genetically resistant subclones in the presence of therapy. In order to parameterize a model of microenvironmental resistance, BT20 cells were cultured in the presence and absence of fibroblasts from 16 different tissues. The degree of resistance conferred by cancer associated fibroblasts in the tumor microenvironment was quantified by treating mono- and co-cultures with letrozole and then measuring the death rates.

Results and Discussion

Our simulations indicate that, even when a mutation is more drug resistant, its outgrowth can be delayed by abundant, low magnitude microenvironmental resistance across large regions of a tumor that lack genetic resistance. These observations hold for different modes of microenvironmental resistance, including juxtacrine signaling, soluble secreted factors, and remodeled ECM. This result helps to explain the remarkable diversity of resistance mechanisms observed in solid tumors, which subverts the presumption that the failure mode that causes the quantitatively fastest growth in the presence of drug should occur most often in the clinic.

Conclusion

Our model results demonstrate that spatial effects can interact with low magnitude of resistance microenvironmental effects to successfully compete against genetic resistance that is orders of magnitude larger. Clinical outcomes of solid tumors are intrinsically connected to their spatial structure, and the tractability of spatial agent-based models like the ones presented here enable us to understand this relationship more completely.

Activation of neural lineage networks and ARHGEF2 in enzalutamide-resistant and neuroendocrine prostate cancer and association with patient outcomes

Background

Treatment-emergent neuroendocrine prostate cancer (NEPC) after androgen receptor (AR) targeted therapies is an aggressive variant of prostate cancer with an unfavorable prognosis. The underlying mechanisms for early neuroendocrine differentiation are poorly defined and diagnostic and prognostic biomarkers are needed.

Methods

We performed transcriptomic analysis on the enzalutamide-resistant prostate cancer cell line C4-2B MDVR and NEPC patient databases to identify neural lineage signature (NLS) genes. Correlation of NLS genes with clinicopathologic features was determined. Cell viability was determined in C4-2B MDVR and H660 cells after knocking down ARHGEF2 using siRNA. Organoid viability of patient-derived xenografts was measured after knocking down ARHGEF2.

Results

We identify a 95-gene NLS representing the molecular landscape of neural precursor cell proliferation, embryonic stem cell pluripotency, and neural stem cell differentiation, which may indicate an early or intermediate stage of neuroendocrine differentiation. These NLS genes positively correlate with conventional neuroendocrine markers such as chromogranin and synaptophysin, and negatively correlate with AR and AR target genes in advanced prostate cancer. Differentially expressed NLS genes stratify small-cell NEPC from prostate adenocarcinoma, which are closely associated with clinicopathologic features such as Gleason Score and metastasis status. Higher ARGHEF2, LHX2, and EPHB2 levels among the 95 NLS genes correlate with a shortened survival time in NEPC patients. Furthermore, downregulation of ARHGEF2 gene expression suppresses cell viability and markers of neuroendocrine differentiation in enzalutamide-resistant and neuroendocrine cells.

Conclusions

The 95 neural lineage gene signatures capture an early molecular shift toward neuroendocrine differentiation, which could stratify advanced prostate cancer patients to optimize clinical treatment and serve as a source of potential therapeutic targets in advanced prostate cancer.

FOXA1 in prostate cancer

Most prostate cancers initially respond to androgen deprivation therapy (ADT). With the long-term application of ADT, localized prostate cancer will progress to castration-resistant prostate cancer (CRPC), metastatic CRPC (mCRPC), and neuroendocrine prostate cancer (NEPC), and the transcriptional network shifted. Forkhead box protein A1 (FOXA1) may play a key role in this process through multiple mechanisms. To better understand the role of FOXA1 in prostate cancer, we review the interplay among FOXA1-targeted genes, modulators of FOXA1, and FOXA1 with a particular emphasis on androgen receptor (AR) function. Furthermore, we discuss the distinct role of FOXA1 mutations in prostate cancer and clinical significance of FOXA1. We summarize possible regulation pathways of FOXA1 in different stages of prostate cancer. We focus on links between FOXA1 and AR, which may play different roles in various types of prostate cancer. Finally, we discuss FOXA1 mutation and its clinical significance in prostate cancer. FOXA1 regulates the development of prostate cancer through various pathways, and it could be a biomarker for mCRPC and NEPC. Future efforts need to focus on mechanisms underlying mutation of FOXA1 in advanced prostate cancer. We believe that FOXA1 would be a prognostic marker and therapeutic target in prostate cancer.

A Drug Repurposing Screen Identifies Fludarabine Phosphate as a Potential Therapeutic Agent for N-MYC Overexpressing Neuroendocrine Prostate Cancers

Neuroendocrine prostate cancer (NEPC) represents a highly aggressive form of prostate tumors. NEPC results from trans-differentiated castration-resistant prostate cancer (CRPC) with increasing evidence indicating that the incidence of NEPC often results from the adaptive response to androgen deprivation therapy. Recent studies have shown that a subset of NEPC exhibits overexpression of the MYCN oncogene along with the loss of tumor suppressing TP53 and RB1 activities. N-MYC is structurally disordered with no binding pockets available on its surface and so far, no clinically approved drug is available. We adopted a drug-repurposing strategy, screened ~1800 drug molecules, and identified fludarabine phosphate to preferentially inhibit the proliferation of N-MYC overexpressing NEPC cells by inducing reactive oxygen species (ROS). We also show that fludarabine phosphate affects N-MYC protein levels and N-MYC transcriptional targets in NEPC cells. Moreover, enhanced ROS production destabilizes N-MYC protein by inhibiting AKT signaling and is responsible for the reduced survival of NEPC cells and tumors. Our results indicate that increasing ROS production by the administration of fludarabine phosphate may represent an effective treatment option for patients with N-MYC overexpressing NEPC tumors.

Neoadjuvant Hormonal Therapy for Prostate Cancer: Morphologic Features and Predictive Parameters of Therapy Response

The primary goals of neoadjuvant hormonal therapy (NHT) in prostate cancer (PCa) are to reduce the size of the tumor, lower positive surgical margin rate, attempt to reach pathologic remission, and improve survival. Although NHT has not been recommended by the National Comprehensive Cancer Network as a primary treatment option for patients with localized PCa, NHT is increasingly used in clinical trials for locally advanced PCa. More importantly, with the development of novel androgen signaling inhibitors, such as abiraterone and enzalutamide, there has been renewed interests in revisiting the role of such treatment in the neoadjuvant setting. Following NHT, the PCa tissues shows characteristic morphologic alterations. Of note, the collapse of malignant glands most likely leads to an artificial increase of Gleason score in the residual disease. Communicating these changes to the clinician in a way that can help assess the tumor's response poses a challenge for pathologists. In addition, little is known of morphologic features and predictive makers both in pretreated and posttreated specimens that can be of value in predicting tumor response to NHT. In the current review, we summarize the morphologic changes associated with neoadjuvant-treated PCa, focusing on the predictive value of pathologic parameters to therapy response. We also describe the evaluation system in the stratification of pathologic response to NHT in PCa management.

Predictors and Real-World Use of Prostate-Specific Radioligand Therapy: PSMA and Beyond

PSMA is a transmembrane protein that is markedly overexpressed in prostate cancer, making it an excellent target for imaging and treating patients with prostate cancer. Several small molecule inhibitors and antibodies of PSMA have been radiolabeled for use as therapeutic agents and are currently under clinical investigation. PSMA-based radionuclide therapy is a promising therapeutic option for men with metastatic prostate cancer. The phase II TheraP study demonstrated superior efficacy, lower side effects, and improved patient-reported outcomes compared with cabazitaxel. The phase III VISION study demonstrated that radionuclide therapy with β-emitter ¹⁷⁷Lu-PSMA-617 can prolong survival and improve quality of life when offered in addition to standard-of-care therapy in men with PSMA-positive metastatic castration-resistant prostate cancer whose disease had progressed with conventional treatments. Nevertheless, up to 30% of patients have inherent resistance to PSMA-based radionuclide therapy, and acquired resistance is inevitable. Hence, strategies to increase the efficacy of PSMA-based radionuclide therapy have been under clinical investigation. These include better patient selection; increased radiation damage delivery via dosimetry-based administered dose or use of α-emitters instead of β-emitters; or using combinatorial approaches to overcome radioresistance mechanisms (innate or acquired), such as with novel hormonal agents, PARP inhibitors, or immunotherapy.

Role of MicroRNAs in Neuroendocrine Prostate Cancer

Therapy-induced neuroendocrine prostate cancer (t-NEPC/NEPC) is an aggressive variant of prostate cancer (PCa) that frequently emerges in castration-resistant prostate cancer (CRPC) under the selective pressure of androgen receptor (AR)-targeted therapies. This variant is extremely aggressive, metastasizes to visceral organs, tissues, and bones despite low serum PSA, and is associated with poor survival rates. It arises via a reversible trans-differentiation process, referred to as ‘neuroendocrine differentiation’ (NED), wherein PCa cells undergo a lineage switch and exhibit neuroendocrine features, characterized by the expression of neuronal markers such as enolase 2 (ENO2), chromogranin A (CHGA), and synaptophysin (SYP). The molecular and cellular mechanisms underlying NED in PCa are complex and not clearly understood, which contributes to a lack of effective molecular biomarkers for diagnosis and therapy of this variant. NEPC is thought to derive from prostate adenocarcinomas by clonal evolution. A characteristic set of genetic alterations, such as dual loss of retinoblastoma (RB1) and tumor protein (TP53) tumor suppressor genes and amplifications of Aurora kinase A (AURKA), NMYC, and EZH2, has been reported to drive NEPC. Recent evidence suggests that microRNAs (miRNAs) are important epigenetic players in driving NED in advanced PCa. In this review, we highlight the role of miRNAs in NEPC. These studies emphasize the diverse role that miRNAs play as oncogenes and tumor suppressors in driving NEPC. These studies have unveiled the important role of cellular processes such as the EMT and cancer stemness in determining NED in PCa. Furthermore, miRNAs are involved in intercellular communication between tumor cells and stromal cells via extracellular vesicles/exosomes that contribute to lineage switching. Recent studies support the promising potential of miRNAs as novel diagnostic biomarkers and therapeutic targets for NEPC.

DNA-repair status should be assessed in treatment-emergent neuroendocrine prostate cancer before platinum-based therapy

OBJECTIVES

This study sought to provide contemporary data from a multi-institution with respect to DNA-repair genes (DRGs) status and its impact on effects of platinum-based chemotherapy in treatment-emergent neuroendocrine prostate cancer (t-NEPC), for which little data exist.

PATIENTS AND METHODS

All patients were retrospectively collected with eligible biopsied tissues for targeted next generation sequencing (NGS). The main outcomes were radiologic progression-free survival and overall survival according to Response Evaluation Criteria in Solid Tumors, version 1.1.

RESULTS

Among the 43 NEPC patients, 13/43 (30%) harbored homozygous deletions, deleterious mutations, or both in DRGs. Eleven patients (11/13, 85%) with DRGs aberrations had effective response, including 7 patients with BRCA1/2 defects and 2 with mismatch repair-deficient caused by MSH2 alterations. While significantly fewer responders (30%) were detected in patients without DRGs aberrations (odds ratio = 12.83, p = 0.003). Compared with patients without genomic DRGs aberrations, the hazard ratio (HR) for radiologic progression in those with DRGs defects was 0.42 (95% confidence interval [CI]: 0.19-0.93), and the HR for death was 0.65 (95% CI: 0.24-1.72). The most common adverse event of Grade 3 or 4 was anemia, as noted in 7 patients (16%).

CONCLUSION

The DRGs status is therapeutically meaningful in t-NEPC. Given the potential responses to platinum-based chemotherapy, our findings support the clinical use of NGS in t-NEPC patients to identify DRGs aberrations.

Aggressive variants of prostate cancer: underlying mechanisms of neuroendocrine transdifferentiation

Prostate cancer is a hormone-driven disease and its tumor cell growth highly relies on increased androgen receptor (AR) signaling. Therefore, targeted therapy directed against androgen synthesis or AR activation is broadly used and continually improved. However, a subset of patients eventually progresses to castration-resistant disease. To date, various mechanisms of resistance have been identified including the development of AR-independent aggressive variant prostate cancer based on neuroendocrine transdifferentiation (NED). Here, we review the highly complex processes contributing to NED. Genetic, epigenetic, transcriptional aberrations and posttranscriptional modifications are highlighted and the potential interplay of the different factors is discussed. Background Aggressive variant prostate cancer (AVPC) with traits of neuroendocrine differentiation emerges in a rising number of patients in recent years. Among others, advanced therapies targeting the androgen receptor axis have been considered causative for this development. Cell growth of AVPC often occurs completely independent of the androgen receptor signal transduction pathway and cells have mostly lost the typical cellular features of prostate adenocarcinoma. This complicates both diagnosis and treatment of this very aggressive disease. We believe that a deeper understanding of the complex molecular pathological mechanisms contributing to transdifferentiation will help to improve diagnostic procedures and develop effective treatment strategies. Indeed, in recent years, many scientists have made important contributions to unravel possible causes and mechanisms in the context of neuroendocrine transdifferentiation. However, the complexity of the diverse molecular pathways has not been captured completely, yet. This narrative review comprehensively highlights the individual steps of neuroendocrine transdifferentiation and makes an important contribution in bringing together the results found so far.

Patient-derived xenograft models of neuroendocrine prostate cancer

In recent years, patient-derived xenografts (PDXs) have attracted much attention as clinically relevant models for basic and translational cancer research. PDXs retain the principal histopathological and molecular heterogeneity of their donor tumors and remain stable across passages. These characteristics allow PDXs to offer a reliable platform for better understanding cancer biology, discovering biomarkers and therapeutic targets, and developing novel therapies. A growing interest in generating neuroendocrine prostate cancer (NEPC) PDX models has been demonstrated, and such models have proven useful in several areas. This review provides a comprehensive summary of currently available NEPC PDX collections, encompassing 1) primary or secondary sites where patient samples were collected, 2) donor patients' treatment histories, 3) morphological features (i.e., small cell and large cell), and 4) genomic alterations. We also highlight suitable models for various research purposes, including identifying therapeutic targets and evaluating drug responses in models with specific genomic backgrounds. Finally, we provide perspectives on the current knowledge gaps and shed light on future applications and improvements of NEPC PDXs.

Endocrine and paracrine characteristics of neuroendocrine prostate cancer

Prostate cancer is a common malignancy affecting men worldwide. While the vast majority of newly diagnosed prostate cancers are categorized as adenocarcinomas, a spectrum of uncommon tumor types occur including those with small cell and neuroendocrine cell features. Benign neuroendocrine cells exist in the normal prostate microenvironment, and these cells may give rise to primary neuroendocrine carcinomas. However, the more common development of neuroendocrine prostate cancer is observed after therapeutics designed to repress the signaling program regulated by the androgen receptor which is active in the majority of localized and metastatic adenocarcinomas. Neuroendocrine tumors are identified through immunohistochemical staining for common markers including chromogranin A/B, synaptophysin and neuron specific enolase (NSE). These markers are also common to neuroendocrine tumors that arise in other tissues and organs such as the gastrointestinal tract, pancreas, lung and skin. Notably, neuroendocrine prostate cancer shares biochemical features with nerve cells, particularly functions involving the secretion of a variety of peptides and proteins. These secreted factors have the potential to exert local paracrine effects, and distant endocrine effects that may modulate tumor progression, invasion, and resistance to therapy. This review discusses the spectrum of factors derived from neuroendocrine prostate cancers and their potential to influence the pathophysiology of localized and metastatic prostate cancer.

Superselective Prostate Artery Embolization for Treatment of Severe Haematuria Secondary to Rapid Progression of Treatment-Induced Neuroendocrine Prostate Cancer: A Case Report

Background

Treatment-induced neuroendocrine prostate cancer (t-NEPC) represents a highly aggressive subtype of castration-resistant prostate cancer that commonly arises from prostate adenocarcinoma (AdPC) after continuous androgen deprivation therapy (ADT). However, current treatments for t-NEPC are limited and far from satisfactory. According to our limited knowledge, report regarding the management of t-NEPC related hemorrhage is rare. Here, we report a case of t-NEPC formation after chronic hormonal therapy accompanying with severe bleeding in primary tumor and share our experiences to deal with the severe hematuria resulting from the progression of t-NEPC tumor.

Case Presentation

An 80-year-old man with a significantly high prostate-specific antigen was diagnosed via pathology as advanced AdPC due to multiple bone metastases. He then received ADT including bicalutamide and goserelin. After 20 months of stable disease, the cancer rapidly progressed and presented with severe gross hematuria caused by bleeding of the primary tumor. The histopathologic analysis of a secondary biopsy of the primary tumor confirmed neuroendocrine prostate cancer, and subsequent genetic testing revealed germ-line mutations in the RB1 and FOXA1. To control the bleeding and relieve symptoms, the patient was treated with superselective prostate artery embolization (PAE). After the left internal pudendal artery and the right prostatic artery were embolized, hematuria was quickly alleviated and disappeared. However, the patient was not a suitable candidate to platinum-based chemotherapy due to weak constitution. Goserelin was continuously applied to maintain castration level of serum testosterone. Meanwhile, palliative radiotherapy to the prostate tumor, high-risk lymph node drainage areas (including iliac and para-aortic lymph nodes, internal iliac lymph nodes, presacral lymph nodes and obturator nerve lymph nodes) and bone metastases (right sacroiliac joint and thoracic vertebra) was performed and relieved the pain. Unfortunately, this patient eventually died of cachexia and multiple organ failure nearly 27 months after initial diagnosis.

Conclusion

To treat severe hematuria caused by progression of t-NEPC, superselective PAE may be a rapid and efficient way to stop bleeding.

Regulation of Neuroendocrine-like Differentiation in Prostate Cancer by Non-Coding RNAs

Neuroendocrine prostate cancer (NEPC) represents a variant of prostate cancer that occurs in response to treatment resistance or, to a much lesser extent, de novo. Unravelling the molecular mechanisms behind transdifferentiation of cancer cells to neuroendocrine-like cancer cells is essential for development of new treatment opportunities. This review focuses on summarizing the role of small molecules, predominantly microRNAs, in this phenomenon. A published literature search was performed to identify microRNAs, which are reported and experimentally validated to modulate neuroendocrine markers and/or regulators and to affect the complex neuroendocrine phenotype. Next, available patients’ expression datasets were surveyed to identify deregulated microRNAs, and their effect on NEPC and prostate cancer progression is summarized. Finally, possibilities of miRNA detection and quantification in body fluids of prostate cancer patients and their possible use as liquid biopsy in prostate cancer monitoring are discussed. All the addressed clinical and experimental contexts point to an association of NEPC with upregulation of miR-375 and downregulation of miR-34a and miR-19b-3p. Together, this review provides an overview of different roles of non-coding RNAs in the emergence of neuroendocrine prostate cancer.

Imaging of Neuroendocrine Prostatic Carcinoma

Neuroendocrine prostate cancer (NEPC) is an aggressive subtype of prostate cancer that typically has a high metastatic potential and poor prognosis in comparison to the adenocarcinoma subtype. Although it can arise de novo, NEPC much more commonly occurs as a mechanism of treatment resistance during therapy for conventional prostatic adenocarcinoma, the latter is also termed as castration-resistant prostate cancer (CRPC). The incidence of NEPC increases after hormonal therapy and they represent a challenge, both in the radiological and pathological diagnosis, as well as in the clinical management. This article provides a comprehensive imaging review of prostatic neuroendocrine tumors.

Case Report: Systemic Treatment and Serial Genomic Sequencing of Metastatic Prostate Adenocarcinoma Progressing to Small Cell Carcinoma

Small cell carcinoma (SCC)/neuroendocrine prostate cancer (NEPC) is a rare and highly aggressive subtype of prostate cancer associated with an AR(androgen receptor)-null phenotype and visceral metastases. This study presents a 44-year-old man originally diagnosed with metastatic hormone-sensitive prostatic adenocarcinoma. After 6-month androgen deprivation therapy (ADT) combined with docetaxel, the patient developed paraplegia. Laminectomy was performed, and a thoracic vertebral biopsy revealed neuroendocrine differentiation and mixed adenocarcinoma. The patient developed liver metastases and experienced stable disease for 4 months following etoposide combined with cisplatin and pembrolizumab. Seminal vesicle biopsy after chemotherapy revealed small-cell cancer. The prostate biopsy specimen also indicated pure SCC. We witnessed the dynamic evolution from pure adenocarcinoma to fully differentiated SCC, leading to obstruction and death. In addition, whole-exome sequencing was performed on both biopsy specimens of the thoracic vertebra at the beginning of castration resistance and that of seminal vesicle after multiple lines of treatment failure. Utilizing phylogenetic reconstruction, we observed that both samples shared a common ancestor clone harboring aberrations in the TP53, RB1, and NF2 genes. We also discovered that driver events in the private subclones of both samples, such as alterations in CDC27 and RUNX1, might have played a significant role in tumor progression or even neuroendocrine differentiation. Tumor biopsy and IHC assessment must be repeated at different stages of progression, because of intrapatient spatial and temporal heterogeneity of adenocarcinoma versus SCC/NEPC. Although, typical treatments including ADT, docetaxel, etoposide, cisplatin, and pembrolizumab provided temporary response, the patient still had a poor prognosis.

Association of intraductal carcinoma of the prostate detected by initial histological specimen and neuroendocrine prostate cancer: A report of three cases

We present three cases of neuroendocrine prostate cancer (NEPC) and histologically investigate the association of intraductal carcinoma of the prostate (IDC-P) and NEPC. Case 1 was a 76-year-old man who had NEPC identified by repeated biopsy specimens when his prostate-specific antigen (PSA) level became elevated 8 years after the initiation of androgen deprivation therapy (ADT). Case 2 was a 70-year-old man who had NEPC detected when multiple bone metastases were found 3 years after the initiation of ADT. Case 3 was a 70-year-old man who was diagnosed with NEPC based on histological examination of transurethral resected specimens. The histological findings in these three cases showed mixed neuroendocrine carcinoma-acinar adenocarcinoma with various proportions of both components. In all three cases, the neuroendocrine carcinoma components were positive for synaptophysin and chromogranin A, whereas the adenocarcinoma components were positive for PSA and NKX3.1. When we retrospectively reviewed the initial hematoxylin and eosin-stained slides, IDC-P was detected in all three cases. Furthermore, we collected nine additional cases of NEPC and found that all six cases with initial biopsy specimens available had an IDC-P component. Detecting IDC-P on initial histological specimens of the prostate may predict transformation to NEPC.

Unravelling the molecular mechanisms of prostate cancer evolution from genotype to phenotype

Prostate cancer (PC) is the most frequently diagnosed cancer and the second leading cause of cancer-related death in men in the Western society. Unfortunately, although the vast majority of patients are initially responsive to androgen-deprivation therapy (ADT), most cases eventually develop from hormone-sensitive prostate cancer (HSPC) to castration-resistant prostate cancer (CRPC). The main reason is PC heterogeneity and evolution during therapy. PC evolution is a continuously progressive process with combination of genomic alterations including canonical AR, TMPRSS2-ERG fusion, SPOP/FOXA1, TP53/RB1/PTEN, BRCA2. Meanwhile, signaling pathways including PI3K, WNT/β-catenin, SRC, IL-6/STAT3 are activated, to promote epithelial mesenchymal transition (EMT), cancer stem cell (CSC)-like features/stemness and neuroendocrine differentiation (NED) of PC. These improve our understanding of the genotype-phenotype relationships. The identification of canonical genetic alterations and signaling pathway activation in PC has shed more insight into genetic background, molecular subtype and disease landscape of PC evolution, resulting in a more flexible role of individual therapies targeting diverse genotype and phenotype presentation.

Utility of whole-body diffusion-weighted magnetic resonance imaging in the management of treatment-related neuroendocrine prostate cancer

INTRODUCTION

Treatment-related neuroendocrine prostate cancer, a rare and aggressive malignancy that emerges during androgen deprivation therapy characterized by low serum prostate-specific antigen concentrations, is challenging to monitor because it is associated with predominantly visceral and lytic bone metastases.

CASE PRESENTATION

We describe the case of a 69-year-old man with treatment-related neuroendocrine prostate cancer in whom the treatment response could be monitored using whole-body diffusion-weighted magnetic resonance imaging in addition to serum concentrations of neuroendocrine markers. The patient responded well to platinum-based chemotherapy and achieved a complete response, as evidenced by these diagnostic modalities.

CONCLUSION

Our case suggests that whole-body diffusion-weighted magnetic resonance imaging is useful in disease management for treatment-related neuroendocrine prostate cancer as well as the potential evaluation of mixed responses and treatment resistance.

Androgen Receptor Signaling and the Emergence of Lethal Neuroendocrine Prostate Cancer With the Treatment-Induced Suppression of the Androgen Receptor: A Literature Review

Androgen receptor signaling primarily influences both the normal growth and proliferation of the prostate gland and the development of prostatic carcinoma. While localized prostate cancers are typically managed with definitive therapies like surgery and radiotherapy, many patients have recurrences in the form of metastatic disease. Androgen deprivation therapy, by way of castration via orchiectomy or with drugs like luteinizing hormone-releasing hormone (commonly called gonadotropin-releasing hormone) agonists and luteinizing hormone-releasing hormone antagonists, is the primary mode of therapy for advanced castration-sensitive prostate cancer. Castration resistance invariably develops in these patients. Further treatment has shifted to newer anti-androgen drugs like enzalutamide or abiraterone and taxane-based chemotherapy. Prolonged inhibition of the androgen receptor signaling pathway causes androgen receptor-independent clonal evolution which leads to the development of treatment-emergent neuroendocrine prostate cancer. All prostate cancers at the initial presentation should undergo evaluation for the markers of neuroendocrine differentiation. Detection of serum biomarkers of neuroendocrine differentiation and circulating tumor cells is a prospective non-invasive method of detecting neuroendocrine transdifferentiation in patients undergoing treatment with androgen receptor pathway inhibitors. It is essential to perform a biopsy in the presence of red flags of neuroendocrine differentiation. Alisertib, an Aurora kinase inhibitor, showed promising clinical benefit in a subgroup of patients with certain molecular alterations. A thorough understanding of the molecular and clinical programming of treatment-emergent neuroendocrine prostate cancer can potentially lead to the development of drugs to prevent the development of this lethal variant of prostate cancer.

Molecular and Functional Links between Neurodevelopmental Processes and Treatment-Induced Neuroendocrine Plasticity in Prostate Cancer Progression

Simple Summary

Treatment-induced neuroendocrine prostate cancer (t-NEPC) is a subtype of castration-resistant prostate cancer (CRPC) which develops under prolonged androgen deprivation therapy. The mechanisms and pathways underlying the t-NEPC are still poorly understood and there are no effective treatments available. Here, we summarize the literature on the molecules and pathways contributing to neuroendocrine phenotype in prostate cancer in the context of their known cellular neurodevelopmental processes. We also discuss the role of tumor microenvironment in neuroendocrine plasticity, future directions, and therapeutic options under clinical investigation for neuroendocrine prostate cancer.

Abstract

Neuroendocrine plasticity and treatment-induced neuroendocrine phenotypes have recently been proposed as important resistance mechanisms underlying prostate cancer progression. Treatment-induced neuroendocrine prostate cancer (t-NEPC) is highly aggressive subtype of castration-resistant prostate cancer which develops for one fifth of patients under prolonged androgen deprivation. In recent years, understanding of molecular features and phenotypic changes in neuroendocrine plasticity has been grown. However, there are still fundamental questions to be answered in this emerging research field, for example, why and how do the prostate cancer treatment-resistant cells acquire neuron-like phenotype. The advantages of the phenotypic change and the role of tumor microenvironment in controlling cellular plasticity and in the emergence of treatment-resistant aggressive forms of prostate cancer is mostly unknown. Here, we discuss the molecular and functional links between neurodevelopmental processes and treatment-induced neuroendocrine plasticity in prostate cancer progression and treatment resistance. We provide an overview of the emergence of neurite-like cells in neuroendocrine prostate cancer cells and whether the reported t-NEPC pathways and proteins relate to neurodevelopmental processes like neurogenesis and axonogenesis during the development of treatment resistance. We also discuss emerging novel therapeutic targets modulating neuroendocrine plasticity.

SLX4IP Promotes Telomere Maintenance in Androgen Receptor-Independent Castration-Resistant Prostate Cancer through ALT-like Telomeric PML Localization

In advanced prostate cancer, resistance to androgen deprivation therapy is achieved through numerous mechanisms, including loss of the androgen receptor (AR) allowing for AR-independent growth. Therapeutic options are limited for AR-independent castration-resistant prostate cancer (CRPC), and defining mechanisms critical for survival is of utmost importance for targeting this lethal disease. Our studies focus on identifying telomere maintenance mechanism (TMM) hallmarks adopted by CRPC to promote survival. TMMs are responsible for telomere elongation to instill replicative immortality and prevent senescence, with the two TMM pathways available being telomerase and alternative lengthening of telomeres (ALT). Here, we show that AR-independent CRPC demonstrates an atypical ALT-like phenotype with variable telomerase expression and activity, whereas AR-dependent models lack discernible ALT hallmarks. In addition, AR-independent CRPC cells exhibited elevated levels of SLX4IP, a protein implicated in promoting ALT. SLX4IP overexpression in AR-dependent C4-2B cells promoted an ALT-like phenotype and telomere maintenance. SLX4IP knockdown in AR-independent DU145 and PC-3 cells led to ALT-like hallmark reduction, telomere shortening, and induction of senescence. In PC-3 xenografts, this effect translated to reduced tumor volume. Using an in vitro model of AR-independent progression, loss of AR in AR-dependent C4-2B cells promoted an atypical ALT-like phenotype in an SLX4IP-dependent manner. Insufficient SLX4IP expression diminished ALT-like hallmarks and resulted in accelerated telomere loss and senescence. IMPLICATIONS: This study demonstrates a unique reliance of AR-independent CRPC on SLX4IP-mediated ALT-like hallmarks and loss of these hallmarks induces telomere shortening and senescence, thereby impairing replicative immortality.

Differential expression of αVβ3 and αVβ6 integrins in prostate cancer progression

Neuroendocrine prostate cancer (NEPrCa) arises de novo or after accumulation of genomic alterations in pre-existing adenocarcinoma tumors in response to androgen deprivation therapies. We have provided evidence that small extracellular vesicles released by PrCa cells and containing the αVβ3 integrin promote neuroendocrine differentiation of PrCa in vivo and in vitro. Here, we examined αVβ3 integrin expression in three murine models carrying a deletion of PTEN (SKO), PTEN and RB1 (DKO), or PTEN, RB1 and TRP53 (TKO) genes in the prostatic epithelium; of these three models, the DKO and TKO tumors develop NEPrCa with a gene signature comparable to those of human NEPrCa. Immunostaining analysis of SKO, DKO and TKO tumors shows that αVβ3 integrin expression is increased in DKO and TKO primary tumors and metastatic lesions, but absent in SKO primary tumors. On the other hand, SKO tumors show higher levels of a different αV integrin, αVβ6, as compared to DKO and TKO tumors. These results are confirmed by RNA-sequencing analysis. Moreover, TRAMP mice, which carry NEPrCa and adenocarcinoma of the prostate, also have increased levels of αVβ3 in their NEPrCa primary tumors. In contrast, the αVβ6 integrin is only detectable in the adenocarcinoma areas. Finally, analysis of 42 LuCaP patient-derived xenografts and primary adenocarcinoma samples shows a positive correlation between αVβ3, but not αVβ6, and the neuronal marker synaptophysin; it also demonstrates that αVβ3 is absent in prostatic adenocarcinomas. In summary, we demonstrate that αVβ3 integrin is upregulated in NEPrCa primary and metastatic lesions; in contrast, the αVβ6 integrin is confined to adenocarcinoma of the prostate. Our findings suggest that the αVβ3 integrin, but not αVβ6, may promote a shift in lineage plasticity towards a NE phenotype and might serve as an informative biomarker for the early detection of NE differentiation in prostate cancer.

Status epilepticus from GABABR antibody positive encephalitis due to de novo mixed small cell and adenocarcinoma of the prostate

We present a case study of a 67-year-old man who presented with a new onset of recurrent tonic-clonic seizures. He had tested positive to gamma-aminobutyric acid B receptor antibodies in his blood and cerebrospinal fluid, and subsequent CT imaging and transrectal biopsy confirmed the presence of a locally advanced mixed small cell and Gleason 9 adenocarcinoma of the prostate. His seizures remained resistant to treatment with multiple antiepileptic drugs, including sodium valproate, clobazam, topiramate, carbamazepine, phenytoin and lacosamide. He progressed to status epilepticus, which required intravenous immunoglobulin and steroids, followed by plasma exchange 1 week later. The status epilepticus was refractory and required multiple admissions to the intensive care unit.

Adding carboplatin to chemotherapy regimens for metastatic castrate-resistant prostate cancer in postsecond generation hormone therapy setting: Impact on treatment response and survival outcomes

BACKGROUND

The clinical course in metastatic castrate-resistant prostate cancer (mCRPC) can be complicated when patients have disease progression after prior treatment with second generation hormone therapy (second HT), such as enzalutamide or abiraterone. Currently, limited data exist regarding the optimal choice of chemotherapy for mCRPC after failing second generation hormone therapy. We sought to evaluate three common chemotherapy regimens in this setting.

METHODS

We retrospectively identified 150 mCRPC patients with disease progression on enzalutamide or abiraterone. Of these 150 patients, 92 patients were chemo-naïve while 58 patients had previously received docetaxel chemotherapy before being started on second HT. After failing second HT, 90 patients were assigned for docetaxel-alone (group A), 33 patients received carboplatin plus docetaxel (group B), while 27 patients received cabazitaxel-alone (Group C). A favorable response was defined by more than or equal to 50% reduction in prostate-specific antigen from the baseline level after a complete course of chemotherapy. Survival outcomes were assessed for 30-month overall survival.

RESULTS

Patients in group (B) were 2.6 times as likely to have a favorable response compared to patients in group (A) (OR = 2.625, 95%CI: 1.15-5.99) and almost three times compared to patients in group (C) (OR = 2.975, 95%CI: 1.04-8.54) (P = .0442). 30-month overall survival was 70.7%, 38.9% and 30.3% for group (B), (A), and (C), respectively (P = .008). We report a Hazard Ratio of 3.1 (95% CI, 1.31-7.35; P = .0037) between patients in group (A) versus those in group (B) and a Hazard Ratio of 4.18 (95% CI, 1.58-11.06; P = .0037) between patients in group (C) compared to those in group (B) CONCLUSION: This data demonstrates improved response and overall survival in treatment-refractory mCRPC with a chemotherapy regimen of docetaxel plus carboplatin when compared to docetaxel alone or cabazitaxel alone. Further investigations are required.

Increased nuclear factor I/B expression in prostate cancer correlates with AR expression

BACKGROUND

Most prostate cancers express androgen receptor (AR), and our previous studies have focused on identifying transcription factors that modify AR function. We have shown that nuclear factor I/B (NFIB) regulates AR activity in androgen-dependent prostate cancer cells in vitro. However, the status of NFIB in prostate cancer was unknown.

METHODS

We immunostained a tissue microarray including normal, hyperplastic, prostatic intraepithelial neoplasia, primary prostatic adenocarcinoma, and castration-resistant prostate cancer tissue samples for NFIB, AR, and synaptophysin, a marker of neuroendocrine differentiation. We interrogated publically available data sets in cBioPortal to correlate NFIB expression and AR and neuroendocrine prostate cancer (NEPCa) activity scores. We analyzed prostate cancer cell lines for NFIB expression via Western blot analysis and used nuclear and cytoplasmic fractionation to assess where NFIB is localized. We performed co-immunoprecipitation studies to determine if NFIB and AR interact.

RESULTS

NFIB increased in the nucleus and cytoplasm of prostate cancer samples versus matched normal controls, independent of Gleason score. Similarly, cytoplasmic AR and synaptophysin increased in primary prostate cancer. We observed strong NFIB staining in primary small cell prostate cancer. The ratio of cytoplasmic-to-nuclear NFIB staining was predictive of earlier biochemical recurrence in prostate cancer, once adjusted for tumor margin status. Cytoplasmic AR was an independent predictor of biochemical recurrence. There was no statistically significant difference between NFIB and synaptophysin expression in primary and castration-resistant prostate cancer, but cytoplasmic AR expression was increased in castration-resistant samples. In primary prostate cancer, nuclear NFIB expression correlated with cytoplasmic NFIB and nuclear AR, while cytoplasmic NFIB correlated with synaptophysin, and nuclear and cytoplasmic AR. In castration-resistant prostate cancer samples, NFIB expression correlated positively with an AR activity score, and negatively with the NEPCa score. In prostate cancer cell lines, NFIB exists in several isoforms. We observed NFIB predominantly in the nuclear fraction of prostate cancer cells with increased cytoplasmic expression seen in castration-resistant cell lines. We observed an interaction between AR and NFIB through co-immunoprecipitation experiments.

CONCLUSION

We have described the expression pattern of NFIB in primary and castration-resistant prostate cancer and its positive correlation with AR. We have also demonstrated AR interacts with NFIB.

A Multi-Analyte Approach for Improved Sensitivity of Liquid Biopsies in Prostate Cancer

Novel androgen receptor (AR) signaling inhibitors have improved the treatment of castration-resistant prostate cancer (CRPC). Nonetheless, the effect of these drugs is often time-limited and eventually most patients become resistant due to various AR alterations. Although liquid biopsy approaches are powerful tools for early detection of such therapy resistances, most assays investigate only a single resistance mechanism. In combination with the typically low abundance of circulating biomarkers, liquid biopsy assays are therefore informative only in a subset of patients. In this pilot study, we aimed to increase overall sensitivity for tumor-related information by combining three liquid biopsy approaches into a multi-analyte approach. In a cohort of 19 CRPC patients, we (1) enumerated and characterized circulating tumor cells (CTCs) by mRNA-based in situ padlock probe analysis, (2) used RT-qPCR to detect cancer-associated transcripts (e.g., AR and AR-splice variant 7) in lysed whole blood, and (3) conducted shallow whole-genome plasma sequencing to detect AR amplification. Although 44–53% of patient samples were informative for each assay, a combination of all three approaches led to improved diagnostic sensitivity, providing tumor-related information in 89% of patients. Additionally, distinct resistance mechanisms co-occurred in two patients, further reinforcing the implementation of multi-analyte liquid biopsy approaches.

Beta-adrenergic signaling on neuroendocrine differentiation, angiogenesis, and metastasis in prostate cancer progression

Prostate cancer is a complex, heterogeneous disease that mainly affects the older male population with a high-mortality rate. The mechanisms underlying prostate cancer progression are still incompletely understood. Beta-adrenergic signaling has been shown to regulate multiple cellular processes as a mediator of chronic stress. Recently, beta-adrenergic signaling has been reported to affect the development of aggressive prostate cancer by regulating neuroendocrine differentiation, angiogenesis, and metastasis. Here, we briefly summarize and discuss recent advances in these areas and their implications in prostate cancer therapeutics. We aim to provide a better understanding of the contribution of beta-adrenergic signaling to the progression of aggressive prostate cancer.