Castration-resistant prostate cancer: AUA Guideline

State-of-the-art in transposable element modulation affected by drugs in malignant prostatic cancer cells

Over recent years, the investigation of transposable elements (TEs) has granted researchers a deeper comprehension of their characteristics and functions, particularly regarding their significance in the mechanisms contributing to cancer development. This manuscript focuses on prostate carcinoma cell lines and offers a comprehensive review intended to scrutinize the associations and interactions between TEs and genes, as well as their response to treatment using various chemical drugs, emphasizing their involvement in cancer progression. We assembled a compendium of articles retrieved from the PubMed database to construct networks demonstrating correlations with genes and pharmaceuticals. In doing so, we linked the transposition of certain TE types to the expression of specific transcripts directly implicated in carcinogenesis. Additionally, we underline that treatment employing different drugs revealed unique patterns of TE reactivation. Our hypothesis gathers the current understanding and guides research toward evidence-based investigations, emphasizing the association between antiviral drugs, chemotherapy, and the reduced expression of TEs in patients affected by prostate cancer.

Genetic Signatures for Distinguishing Chemo-Sensitive from Chemo-Resistant Responders in Prostate Cancer Patients

Prostate cancer remains a significant public health concern in sub-Saharan Africa, particularly impacting South Africa with high mortality rates. Despite many years of extensive research and significant financial expenditure, there has yet to be a definitive solution to prostate cancer. It is not just individuals who vary in their response to treatment, but even different nodules within the same tumor exhibit unique transcriptome patterns. These distinctions extend beyond mere differences in gene expression levels to encompass the control and networking of individual genes. Escalating chemotherapy resistance in prostate cancer patients has prompted increased research into its underlying mechanisms. The heterogeneous nature of transcriptomic organization among men makes the pursuit of universal biomarkers and one-size-fits-all treatments impractical. This study delves into the expression of drug resistance-associated genes, ABCB1 and CYP1B1, in cancer cells. Employing bioinformatics, we explored the molecular pathways and cascades linked to drug resistance following upregulation of these genes. Samples were obtained from archived prostate cancer patient specimens through pre-treatment biopsies of two categories: good vs. poor responders, with cDNAs synthesized from isolated RNAs subjected to qPCR analysis. The results revealed increased ABCB1 and CYP1B1 expression in tumor samples of the poor responders. Gene enrichment and network analysis associated ABCB1 with ABC transporters and LncRNA-mediated therapeutic resistance (WP3672), while CYP1B1 was linked to ovarian steroidogenesis, tryptophan metabolism, steroid hormone biosynthesis, benzo(a)pyrene metabolism, the sulindac metabolic pathway, and the estrogen receptor pathway, which are associated with drug resistance. Both ABCB1 and CYP1B1 correlated with microRNAs in cancer and the Nuclear Receptors Meta-Pathway. STRING analysis predicted protein-protein interactions of ABCB1 and CYP1B1 with Glutathione S-transferase Pi, Catechol O-methyltransferase, UDP-glucuronosyltransferase 1-6, Leucine-rich Transmembrane and O-methyltransferase (LRTOMT), and Epoxide hydrolase 1, with scores of 0.973, 0.971, 0.966, 0.966, and 0.966, respectively. Furthermore, molecular docking analysis of the chemotherapy drug, docetaxel, with CYP1B1 and ABCB1 revealed robust molecular interactions, with binding energies of -20.37 and -15.25 Kcal/mol, respectively. These findings underscore the susceptibility of cancer patients to drug resistance due to increased ABCB1 and CYP1B1 expression in tumor samples from patients in the poor-responders category that affects associated molecular pathways. The potent molecular interactions of ABCB1 and CYP1B1 with docetaxel further emphasize the potential basis for chemotherapy resistance.

Real-World Overall Survival and Treatment Patterns by PTEN Status in Metastatic Castration-Resistant Prostate Cancer

PURPOSE

It is estimated that the PTEN tumor suppressor gene is functionally lost in 40%-50% of patients with metastatic castration-resistant prostate cancer (mCRPC). There is limited information on the prognostic significance of PTEN status identified with genomic testing. This real-world cohort study assessed PTEN as a genetic biomarker using data from US-based oncology practices.

METHODS

This retrospective real-world cohort study used a deidentified US-based metastatic prostate cancer clinicogenomic database linked to longitudinal clinical data derived from electronic health records. Patients were aged 18 years and older and diagnosed with mCRPC between January 1, 2018, and June 30, 2021. Comprehensive genomic profiling (CGP) of tumor specimens was performed using next-generation sequencing. First-line (1L) and second-line (2L) treatment patterns were assessed and stratified by PTEN status. Kaplan-Meier methods and a multivariable Cox model were used to compare the real-world overall survival by PTEN status among patients who received 1L novel hormone therapy or taxanes.

RESULTS

In patients with mCRPC who underwent CGP, PTEN loss of function (LOF) was associated with decreased survival compared with intact PTEN (hazard ratio, 1.61 [95% CI, 1.07 to 2.42]; P = .024). The results were not influenced by 1L treatment type. 1L treatment patterns were similar between intact PTEN and PTEN LOF subgroups, with abiraterone and enzalutamide being the two most common treatments in both groups. Patients with PTEN LOF were less likely to receive 2L treatments than patients with intact PTEN.

CONCLUSION

PTEN LOF, identified with genomic testing, was associated with decreased survival and negative prognoses in patients with mCRPC.

Contemporary Systemic Therapy Intensification for Prostate Cancer: A Review for General Practitioners in Oncology

Prostate cancer accounts for a significant proportion of cancer diagnoses in Canadian men. Over the past decade, the therapeutic landscape for the management of metastatic prostate cancer has undergone rapid changes. Novel strategies use hormonal agents, chemotherapy, homologous recombination repair inhibitors, and radioligand therapy or combination strategies in addition to androgen deprivation therapy. In this review, we summarize the available data addressing key therapeutic areas along the disease continuum and focus on practical aspects for general practitioners in oncology managing patients with metastatic prostate cancer.

Comprehensive genomic profiling testing in Japanese castration-resistant prostate cancer patients: results of a single-center retrospective cohort study

OBJECTIVE

Comprehensive genomic profiling testing using a hybrid-capture next-generation sequencing is commonly used in clinical practice to employ precision medicine in cancer treatment worldwide. In this study, we aimed to analyze the profiles obtained using comprehensive genomic profiling testing that was performed in Japanese castration-resistant prostate cancer patients and to discuss the genetic findings in a real-world setting.

METHODS

A total of 60 cases and 57 castration-resistant prostate cancer patients underwent comprehensive genomic profiling testing between 1 January 2021 and 31 December 2022. Four types of comprehensive genomic profiling testing were selected, and clinically significant cancer-specific gene alterations were identified.

RESULTS

The median age of patients was 74 years, and the median prostate-specific antigen value at the time of submission was 18.6 ng/ml. Fifty-seven (95%) of 60 cases were metastatic castration-resistant prostate cancers, and 3 cases (5%) were non-metastatic. Among all genetic alterations, androgen-receptor alteration was the most frequently detected in 17 cases (28.3%), followed by 15 cases of TP53 (25.0%), 14 cases of CDK12 (23.3%), 10 cases of phosphatase and tensin homolog (16.7%) and 9 cases of ATM (15.0%) mutations. A total of 13 patients (21.7%) received systemic therapy according to the comprehensive genomic profiling testing results. Overall, the survival rate was significantly greater in the group treated through systemic therapy based on comprehensive genomic profiling testing compared with the group without new therapeutic treatment (P = 0.041).

CONCLUSIONS

Comprehensive genomic profiling testing is recommended in castration-resistant prostate cancer patients identified as resistant to standard therapy as this can provide a new therapeutic option.

Inflammation in Prostate Cancer: Exploring the Promising Role of Phenolic Compounds as an Innovative Therapeutic Approach

Prostate cancer (PCa) remains a significant global health concern, being a major cause of cancer morbidity and mortality worldwide. Furthermore, profound understanding of the disease is needed. Prostate inflammation caused by external or genetic factors is a central player in prostate carcinogenesis. However, the mechanisms underlying inflammation-driven PCa remain poorly understood. This review dissects the diagnosis methods for PCa and the pathophysiological mechanisms underlying the disease, clarifying the dynamic interplay between inflammation and leukocytes in promoting tumour development and spread. It provides updates on recent advances in elucidating and treating prostate carcinogenesis, and opens new insights for the use of bioactive compounds in PCa. Polyphenols, with their noteworthy antioxidant and anti-inflammatory properties, along with their synergistic potential when combined with conventional treatments, offer promising prospects for innovative therapeutic strategies. Evidence from the use of polyphenols and polyphenol-based nanoparticles in PCa revealed their positive effects in controlling tumour growth, proliferation, and metastasis. By consolidating the diverse features of PCa research, this review aims to contribute to increased understanding of the disease and stimulate further research into the role of polyphenols and polyphenol-based nanoparticles in its management.

Castration-Resistant Prostate Cancer: From Uncovered Resistance Mechanisms to Current Treatments

Prostate cancer (PC) is the second most common cancer in men worldwide. Despite recent advances in diagnosis and treatment, castration-resistant prostate cancer (CRPC) remains a significant medical challenge. Prostate cancer cells can develop mechanisms to resist androgen deprivation therapy, such as AR overexpression, AR mutations, alterations in AR coregulators, increased steroidogenic signaling pathways, outlaw pathways, and bypass pathways. Various treatment options for CRPC exist, including androgen deprivation therapy, chemotherapy, immunotherapy, localized or systemic therapeutic radiation, and PARP inhibitors. However, more research is needed to combat CRPC effectively. Further investigation into the underlying mechanisms of the disease and the development of new therapeutic strategies will be crucial in improving patient outcomes. The present work summarizes the current knowledge regarding the underlying mechanisms that promote CRPC, including both AR-dependent and independent pathways. Additionally, we provide an overview of the currently approved therapeutic options for CRPC, with special emphasis on chemotherapy, radiation therapy, immunotherapy, PARP inhibitors, and potential combination strategies.

Exploring the potential of single-metals (Cu, Ni, Zn) decorated Al12N12 nanostructures as sensors for flutamide anticancer drug

In recent years, scientists have been actively exploring and expanding biosensor technologies and materials to meet the growing societal demands in healthcare and other fields. This study aims to revolutionize biosensors by using density functional theory (DFT) at the cutting-edge B3LYP-GD3BJ/def2tzsvp level to investigate the sensing capabilities of (Cu, Ni, and Zn) doped on Aluminum nitride (Al12N12) nanostructures. Specifically, we focus on their potential to detect, analyze, and sense the drug flutamide (FLU) efficiently. Through advanced computational techniques, we explore molecular interactions to pave the way for highly effective and versatile biosensors. The adsorption energy values of -38.76 kcal/mol, -39.39 kcal/mol, and -39.37 kcal/mol for FLU@Cu-Al12N12, FLU@Ni-Al12N12, and FLU@Zn-Al12N12, respectively, indicate that FLU chemically adsorbs on the studied nanostructures. The reactivity and conductivity of the system follow a decreasing pattern: FLU@Cu-Al12N12 > FLU@Ni-Al12N12 > FLU@Zn-Al12N12, with a band gap of 0.267 eV, 2.197 eV, and 2.932 eV, respectively. These results suggest that FLU preferably adsorbs on the Al12N12@Cu surface. Natural bond orbital analysis reveals significant transitions in the studied system. Quantum theory of atom in molecule (QTAIM) and Non-covalent interaction (NCI) analysis confirm the nature and strength of interactions. Overall, our findings indicate that the doped surfaces show promise as electronic and biosensor materials for detection of FLU in real-world applications. We encourage experimental researchers to explore the use of (Cu, Ni, and Zn) doped on Aluminum nitride (Al12N12), particularly Al12N12@Cu, for biosensor applications.

Molecular Insight into Prostate Cancer: Preventive Role of Selective Bioactive Molecules

Prostate cancer (CaP) is one of the most prevalent male malignancies, accounting for a considerable number of annual mortalities. However, the prompt identification of early-stage CaP often faces delays due to diverse factors, including socioeconomic inequalities. The androgen receptor (AR), in conjunction with various other signaling pathways, exerts a central influence on the genesis, progression, and metastasis of CaP, with androgen deprivation therapy (ADT) serving as the primary therapeutic strategy. Therapeutic modalities encompassing surgery, chemotherapy, hormonal intervention, and radiotherapy have been formulated for addressing early and metastatic CaP. Nonetheless, the heterogeneous tumor microenvironment frequently triggers the activation of signaling pathways, culminating in the emergence of chemoresistance, an aspect to which cancer stem cells (CSCs) notably contribute. Phytochemicals emerge as reservoirs of bioactive agents conferring manifold advantages against human morbidity. Several of these phytochemicals demonstrate potential chemoprotective and chemosensitizing properties against CaP, with selectivity exhibited towards malignant cells while sparing their normal counterparts. In this context, the present review aims to elucidate the intricate molecular underpinnings associated with metastatic CaP development and the acquisition of chemoresistance. Moreover, the contributions of phytochemicals to ameliorating CaP initiation, progression, and chemoresistance are also discussed.

SIRT2 promotes cell proliferation and migration through mediating ERK1/2 activation and lactosylceramide accumulation in prostate cancer

BACKGROUND

Prostate cancer (PCa) is an age-related malignancy with a high incidence and mortality rate due to lack of efficacy drugs for its therapy in late castration-resistant stage. Sirtuin 2 (SIRT2), a NAD⁺ -dependent protein deacetylase, is associated with age-related diseases. However, SIRT2 roles in PCa are unclear yet.

METHODS

Data of SIRT2 expression were extracted from TCGA cohort and GSE54460 cohort. Realtime quantitative PCR and immunohistochemistry were employed to analyze the expression of SIRT2 in PCa tissues. Cell counting Kit-8 assay, lentiviral transduction, flow cytometry, transwell experiments, western blot and metabolomic analysis were performed to explore the functions of SIRT2.

RESULTS

SIRT2 exhibited increased expression in castration-resistant prostate cancer (CRPC) and neuroendocrine prostate cancer (NEPC). Overexpression of SIRT2 promoted cell proliferation, the proportion of S phase, migration and invasion, and reduced apoptosis rate. The increased phosphorylated ERK1/2 indicated the regulation of SIRT2 to cell proliferation, migration and invasion through activation of ERK1/2 pathway. Furthermore, SIRT2 affected cell metabolic profile and induces lactosylceramide production through upregulation of B4GALT5, which further contributes cell migration and invasion.

CONCLUSIONS

Our data suggested that SIRT2 is overexpressed in CRPC and NEPC and could promote cell growth and migration through activating ERK1/2 pathway and inducing lactosylceramide production, indicating that SIRT2 has the potential to be a new target for the treatment of PCa.

Identification of castration-dependent and -independent driver genes and pathways in castration-resistant prostate cancer (CRPC)

Background

Prostate cancer (PCa) is one of the most diagnosed cancers in the world. PCa inevitably progresses to castration-resistant prostate cancer (CRPC) after androgen deprivation therapy treatment, and castration-resistant state means a shorter survival time than other causes. Here we aimed to define castration-dependent and -independent diver genes and molecular pathways in CRPC which are responsible for such lethal metastatic events.

Methods

By employing digital gene expression (DGE) profiling, the alterations of the epididymal gene expression profile in the mature and bilateral castrated rat were explored. Then we detect and characterize the castration-dependent and -independent genes and pathways with two data set of CPRC-associated gene expression profiles publicly available on the NCBI.

Results

We identified 1,632 up-regulated and 816 down-regulated genes in rat’s epididymis after bilateral castration. Differential expression analysis of CRPC samples compared with the primary PCa samples was also done. In contrast to castration, we identified 97 up-regulated genes and 128 down-regulated genes that changed in both GEO dataset and DGE profile, and 120 up-regulated genes and 136 down-regulated genes changed only in CRPC, considered as CRPC-specific genes independent of castration. CRPC-specific DEGs were mainly enriched in cell proliferation, while CRPC-castration genes were associated with prostate gland development. NUSAP1 and NCAPG were identified as key genes, which might be promising biomarkers of the diagnosis and prognosis of CRPC.

Conclusion

Our study will provide insights into gene regulation of CRPC dependent or independent of castration and will improve understandings of CRPC development and progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12894-022-01113-5.

A seven-gene prognosis model to predict biochemical recurrence for prostate cancer based on the TCGA database

Background

The incidence rate of prostate cancer is increasing rapidly. This study aims to explore the gene-associated mechanism of prostate cancer biochemical recurrence (BCR) after radical prostatectomy and to construct a biochemical recurrence of prostate cancer prognostic model.

Methods

The DEseq2 R package was used for the differential expression of mRNA. The ClusterProfiler R package was used to analyze the functional enrichment of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) to explore related mechanisms. The Survival, Survminer, and My.stepwise R packages were used to construct the prognostic model to predict the biochemical recurrence-free probability. The RMS R package was used to draw the nomogram. For evaluating the prognostic model, the timeROC R package was used to draw the time-dependent ROC curve (receiver operating characteristic curve).

Result

To investigate the association between mRNA and prostate cancer, we performed differential expression analysis on the TCGA (The Cancer Genome Atlas) database. Seven protein-coding genes (VWA5B2, ARC, SOX11, MGAM, FOXN4, PRAME, and MMP26) were picked as independent prognostic genes by regression analysis. Based on their Cox coefficient, a risk score formula was proposed. According to the risk scores, patients were divided into high- and low-risk groups based on the median score. Kaplan-Meier plot curves showed that the low-risk group had a better biochemical recurrence-free probability compared to the high-risk group. The 1-year, 3-year, and 5-year AUCs (areas under the ROC curve) of the model were 77%, 81%, and 86%, respectively. In addition, we built a nomogram based on the result of multivariate Cox regression analysis. Furthermore, we select the GSE46602 dataset as our external validation. The 1-year, 3-year, and 5-year AUCs of BCR-free probability were 83%, 82%, and 80%, respectively. Finally, the levels of seven genes showed a difference between PRAD tissues and adjacent non-tumorous tissues.

Conclusions

This study shows that establishing a biochemical recurrence prediction prognostic model comprising seven protein-coding genes is an effective and precise method for predicting the progression of prostate cancer.

Prostate Cancer Review: Genetics, Diagnosis, Treatment Options, and Alternative Approaches

Simple Summary

Prostate cancer affects men of all racial and ethnic groups and leads to higher rates of mortality in those belonging to a lower socioeconomic status due to late detection of the disease. There is growing evidence that suggests the contribution of an individual’s genetic profile to prostate cancer. Currently used prostate cancer treatments have serious adverse effects; therefore, new research is focusing on alternative treatment options such as the use of genetic biomarkers for targeted gene therapy, nanotechnology for controlled targeted treatment, and further exploring medicinal plants for new anticancer agents. In this review, we describe the recent advances in prostate cancer research.

Abstract

Prostate cancer is one of the malignancies that affects men and significantly contributes to increased mortality rates in men globally. Patients affected with prostate cancer present with either a localized or advanced disease. In this review, we aim to provide a holistic overview of prostate cancer, including the diagnosis of the disease, mutations leading to the onset and progression of the disease, and treatment options. Prostate cancer diagnoses include a digital rectal examination, prostate-specific antigen analysis, and prostate biopsies. Mutations in certain genes are linked to the onset, progression, and metastasis of the cancer. Treatment for localized prostate cancer encompasses active surveillance, ablative radiotherapy, and radical prostatectomy. Men who relapse or present metastatic prostate cancer receive androgen deprivation therapy (ADT), salvage radiotherapy, and chemotherapy. Currently, available treatment options are more effective when used as combination therapy; however, despite available treatment options, prostate cancer remains to be incurable. There has been ongoing research on finding and identifying other treatment approaches such as the use of traditional medicine, the application of nanotechnologies, and gene therapy to combat prostate cancer, drug resistance, as well as to reduce the adverse effects that come with current treatment options. In this article, we summarize the genes involved in prostate cancer, available treatment options, and current research on alternative treatment options.

Factors Influencing Outcome Post–Radium-223 Dichloride in Castrate Resistant Prostate Cancer: A Review of Some Real-World Challenges

Aim Radium-223 has been the first-approved targeted Alpha therapy agent. We retrospectively assessed different factors influencing the overall survival (OS) and patient management.

Setting and Design Thirty-two metastatic castration-resistant prostate cancer (mCRPC) patients' hematological parameters, number of cycles, performance status, and toxicities were evaluated for OS. Radium 223 dichloride (Radium-223) was administered every 4 weeks for a maximum of six cycles. Primary and secondary end points were OS, progression free survival (PFS), therapy toxicities, change in performance status, biochemical response, and skeletal-related events (SREs).

Materials and Methods Patients' median age was 77 years (range: 57–90 years) and median follow-up was 399 days (range: 5–1,761 days). A total of 163 cycles were administered in 32 patients, with 4 or less cycles in 8 patients (25%) and 5 or more cycles in 24 patients (75%). Among eight patients with 4 or less cycles, three patients died, of which two patients died due to neutropenic sepsis.

Statistical Analysis Mann–Whitney test was used to compare the cycle groups; Spearman's correlation coefficient was used to see the relation of different variables with OS. Log rank test was used for group comparison while Kaplan–Meier survivorship was used for OS.

Results Statistical correlation was seen between the number of cycles (p=0.037) and hemoglobin (p=0.028). Kaplan–Meier OS (p=0.038) was correlated with the number of cycles (≤ 4 cycles and ≥ 5 cycles). OS was 173 days in patients with one to four cycles, 226 days in five cycles, and 493 days in six cycles. Myelosuppression leading to stopping of full six cycles was seen in 7 of 32 patients (22%) and significantly correlated to inferior OS (p=0.048).

Conclusion Higher number of Radium-223 cycles was seen to be associated with better OS. Prior myelosuppression was associated with poor OS. Patients with better hematological profile were more likely to complete the maximum number of the cycles with a better OS.

Next-generation engineered nanogold for multimodal cancer therapy and imaging: a clinical perspectives

Cancer is one of the significant threats to human life. Although various latest technologies are currently available to treat cancer, it still accounts for millions of death each year worldwide. Thus, creating a need for more developed and novel technologies to combat this deadly condition. Nanoparticles-based cancer therapeutics have offered a promising approach to treat cancer effectively while minimizing adverse events. Among various nanoparticles, nanogold (AuNPs) are biocompatible and have proved their efficiency in treating cancer because they can reach tumors via enhanced permeability and retention effect. The size and shape of the AuNPs are responsible for their diverse therapeutic behavior. Thus, to modulate their therapeutic values, the AuNPs can be synthesized in various shapes, such as spheres, cages, flowers, shells, prisms, rods, clusters, etc. Also, attaching AuNPs with single or multiple targeting agents can facilitate the active targeting of AuNPs to the tumor tissue. The AuNPs have been much explored for photothermal therapy (PTT) to treat cancer. In addition to PTT, AuNPs-based nanoplatforms have been investigated for combinational multimodal therapies in the last few years, including photodynamic therapy, chemotherapy, radiotherapy, immunotherapy, etc., to ablate cancer cells. Thus, the present review focuses on the recent advancements in the functionalization of AuNPs-based nanoconstructs for cancer imaging and therapy using combinatorial multimodal approaches to treat various cancers.

Development of a novel castration-resistant orthotopic prostate cancer model in New Zealand White rabbit

BACKGROUND

Prostate cancer (PCa) models in mice and rats are limited by their size and lack of a clearly delineated or easily accessible prostate gland. The canine PCa model is currently the only large animal model which can be used to test new preclinical interventions but is costly and availability is sparse. As an alternative, we developed an orthotopic human prostate tumor model in an immunosuppressed New Zealand White rabbit. Rabbits are phylogenetically closer to humans, their prostate gland is anatomically similar, and its size allows for clinically-relevant testing of interventions.

METHODS

Rabbits were immunosuppressed via injection of cyclosporine. Human PC3pipGFP PCa cells were injected into the prostate via either (a) laparotomy or (b) transabdominal ultrasound (US) guided injection. Tumor growth was monitored using US and magnetic resonance imaging (MRI). Contrast-enhanced ultrasound (CEUS) imaging using nanobubbles and Lumason microbubbles was also performed to examine imaging features and determine the optimal contrast dose required for enhanced visualization of the tumor. Ex vivo fluorescence imaging, histopathology, and immunohistochemistry analyses of the collected tissues were performed to validate tumor morphology and prostate-specific membrane antigen (PSMA) expression.

RESULTS

Immunosuppression and tumor growth were, in general, well-tolerated by the rabbits. Fourteen out of 20 rabbits, with an average age of 8 months, successfully grew detectable tumors from Day 14 onwards after cell injection. The tumor growth rate was 39 ± 25 mm² per week. CEUS and MRI of tumors appear hypoechoic and T2 hypointense, respectively, relative to normal prostate tissue. Minimally invasive US-guided tumor cell injection proved to be a better method compared to laparotomy due to the shorter recovery time required for the rabbits following injection. Among the rabbits that grew tumors, seven had tumors both inside and outside the prostate, three had tumors only inside the prostate, and four had tumors exclusively outside of the prostate. All tumors expressed the PSMA receptor.

CONCLUSIONS

We have established, for the first time, an orthotopic PCa rabbit model via percutaneous US-guided tumor cell inoculation. This animal model is an attractive, clinically relevant intermediate step to assess preclinical diagnostic and therapeutic compounds.

Current Status of Monoclonal Antibodies-Based Therapies in Castration-Resistant Prostate Cancer: A Systematic Review and Meta-Analysis of Clinical Trials

Background

Multiple patients with prostate cancer become resistant to castration therapies, which is termed castration-resistant prostate cancer (CRPC).

Purpose

The purpose of this review is to assess the status of efficacy (≥50% decline in prostate-specific antigen (PSA), progression-free survival (PFS), and overall survival (OS)) and safety (grade 3-4 adverse effects) of monoclonal antibodies in CRPC.

Data source

We searched databases including PubMed, Embase, Cochrane, Web of Science, and ClinicalTrials.gov.

Results

Hazard ratios of PFS and OS were 0.77 (95% CI = 0.69-0.87, I² = 53%) and 0.98 (95% CI = 0.86-1.11, I² = 40%), respectively, in the favor of monoclonal antibodies as compared to placebo. Risk ratio (RR) of >50% decline in PSA was 1.99 (95% CI = 0.97-4.08, I² = 53%) in favor of monoclonal antibodies. Pooled incidence of >50% decline in PSA levels was 15% (95% CI = 0.1-0.23, I² = 83%), 29% (95% CI = 0.14-0.51, I² = 93%), 63% (95% CI = 0.49-0.76, I² = 77%), and 88% (95% CI = 0.81-0.93, I² = 0%) in single, two, three, and four-drug regimens, respectively.

Conclusion

Monoclonal antibodies are well tolerated and showed better PFS as compared to placebo. However, OS was only improved with ipilimumab. Denosumab delayed skeletal-related adverse events as compared to zoledronic acid. More multicenter double-blind clinical trials may be needed to confirm these results.

Altered glucuronidation deregulates androgen dependent response profiles and signifies castration resistance in prostate cancer

Glucuronidation controls androgen levels in the prostate and the dysregulation of enzymes in this pathway is associated with castration resistant prostate cancer. UDP-glucose dehydrogenase (UGDH) produces UDP-glucuronate, the essential precursor for glucuronidation, and its expression is elevated in prostate cancer. We compared protein and metabolite levels relevant to the glucuronidation pathway in five prostate cancer patient-derived xenograft models paired with their isogenic counterparts that were selected in vivo for castration resistant (CR) recurrence. All pairs showed changes in UGDH and associated enzymes and metabolites that were consistent with those we found in an isogenic androgen dependent (AD) and CR LNCaP prostate cancer model. Ectopic overexpression of UGDH in LNCaP AD cells blunted androgen-dependent gene expression, increased proteoglycan synthesis, significantly increased cell growth compared to controls, and eliminated dose responsive growth suppression with enzalutamide treatment. In contrast, the knockdown of UGDH diminished proteoglycans, suppressed androgen dependent growth irrespective of androgens, and restored androgen sensitivity in CR cells. Importantly, the knockdown of UGDH in both LNCaP AD and CR cells dramatically sensitized these cells to enzalutamide. These results support a role for UGDH in androgen responsiveness and a target for therapeutic strategies in advanced prostate cancer.

A Review of the Pathophysiological Mechanisms Underlying Castration-resistant Prostate Cancer

Androgen deprivation therapy or ADT is one of the cornerstones of management of locally advanced or metastatic prostate cancer, alongside radiation therapy. However, despite early response, most advanced prostate cancers progress into an androgen unresponsive or castrate resistant state, which hitherto remains an incurable entity and the second leading cause of cancer-related mortality in men in the US. Recent advances have uncovered multiple complex and intermingled mechanisms underlying this transformation. While most of these mechanisms revolve around androgen receptor (AR) signaling, novel pathways which act independently of the androgen axis are also being discovered. The aim of this article is to review the pathophysiological mechanisms that help bypass the apoptotic effects of ADT to create castrate resistance. The article discusses castrate resistance mechanisms under two categories: 1. Direct AR dependent pathways such as amplification or gain of function mutations in AR, development of functional splice variants, posttranslational regulation, and pro-oncogenic modulation in the expression of coactivators vs corepressors of AR. 2. Ancillary pathways involving RAS/MAP kinase, TGF-beta/SMAD pathway, FGF signaling, JAK/STAT pathway, Wnt-Beta catenin and hedgehog signaling as well as the role of cell adhesion molecules and G-protein coupled receptors. miRNAs are also briefly discussed. Understanding the mechanisms involved in the development and progression of castration-resistant prostate cancer is paramount to the development of targeted agents to overcome these mechanisms. A number of targeted agents are currently in development. As we strive for more personalized treatment across oncology care, treatment regimens will need to be tailored based on the type of CRPC and the underlying mechanism of castration resistance.

Interim and end-treatment 18F-Fluorocholine PET/CT and bone scan in prostate cancer patients treated with Radium 223 dichloride

To assess the predictive and prognostic aim of interim and end-treatment 18F-fluorocholine PET/CT (FCH-PET/CT) and 99mTc-methilen diphosphonate bone scintigraphy (BS) in patients with castration-resistant prostate cancer and bone metastases (CRPC-BM) treated with Radium 223 dichloride (223Ra). Prospective and multicentre ChoPET-Rad study including 82 patients with CRPC-BM. Baseline, after 3 (interim) and 6 doses (end-treatment) BS and FCH PET/CT were performed in patients who meet the study criteria. Clinical variables, imaging and clinical progression were obtained and their association with progression free survival (PFS), and overall survival (OS) was studied. Agreement between BS and FCH PET/CT response was assessed using Kappa (K) analysis. Median of PFS and OS was 3 and 16 months, respectively. Agreement between interim BS and FCH PET/CT was weak (K: 0.28; p = 0.004). No agreement was observed between end-treatment diagnostic studies. Interim and end-treatment FCH PET/CT were related to PFS (p = 0.011 and p < 0.001, respectively). Therapeutic failure and interim BS and FCH PET/CT showed association with OS (p < 0.001, p = 0.037 and p = 0.008, respectively). Interim and end-treatment FCH PET/CT were good predictors of biochemical progression in patients treated with 223Ra. Therapeutic failure and progression in interim BS or FCH PET/CT were adverse factors for OS.

Direct interaction of β-catenin with nuclear ESM1 supports stemness of metastatic prostate cancer

Wnt/β-catenin signaling is frequently activated in advanced prostate cancer and contributes to therapy resistance and metastasis. However, activating mutations in the Wnt/β-catenin pathway are not common in prostate cancer, suggesting alternative regulations may exist. Here, we report that the expression of endothelial cell-specific molecule 1 (ESM1), a secretory proteoglycan, is positively associated with prostate cancer stemness and progression by promoting Wnt/β-catenin signaling. Elevated ESM1 expression correlates with poor overall survival and metastasis. Accumulation of nuclear ESM1, instead of cytosolic or secretory ESM1, supports prostate cancer stemness by interacting with the ARM domain of β-catenin to stabilize β-catenin-TCF4 complex and facilitate the transactivation of Wnt/β-catenin signaling targets. Accordingly, activated β-catenin in turn mediates the nuclear entry of ESM1. Our results establish the significance of mislocalized ESM1 in driving metastasis in prostate cancer by coordinating the Wnt/β-catenin pathway, with implications for its potential use as a diagnostic or prognostic biomarker and as a candidate therapeutic target in prostate cancer.

Genomic Testing in Patients with Metastatic Castration-resistant Prostate Cancer: A Pragmatic Guide for Clinicians

CONTEXT

Genomic testing is becoming increasingly important in patients with advanced prostate cancer (PC) and is being incorporated in clinical practice to guide treatment.

OBJECTIVE

To review the current understanding of genomic alterations and the status of genomic testing in patients with metastatic castration-resistant PC (mCRPC), and the potential use of genomic tests in clinical practice.

EVIDENCE ACQUISITION

We reviewed recent publications (past 15 yr) from PubMed, proceedings of scientific conferences, and published guidelines. Reports on mCRPC in the following areas were selected: development, testing, and validation of techniques for identifying genomic alterations; molecular characterization; and trials of genetically targeted therapies.

EVIDENCE SYNTHESIS

mCRPC tumors harbor molecular alterations that are possible targets for treatment, and a number of therapies are in development to exploit these alterations (eg, PD-1 inhibitors, PARP inhibitors, tyrosine kinase inhibitors). Next-generation sequencing of DNA from tumor tissue can identify somatic alterations that would not be identified by germline testing. Work is ongoing to evaluate the use of less invasive somatic testing methods (eg, sequencing of cell-free circulating tumor DNA). Current international guidelines recommend germline and/or somatic testing for men with advanced and/or high-risk PC regardless of family history to identify those with homologous recombination repair gene mutations or mismatch repair defects/microsatellite instability who may be eligible for treatment with a PARP inhibitor or pembrolizumab, respectively.

CONCLUSIONS

Genomic testing for mCRPC may provide information on prognostic, predictive, and resistance biomarkers. Although the incorporation of testing into clinical practice remains challenging, routine genomic testing of men with advanced PC is recommended to guide management and treatment decisions.

PATIENT SUMMARY

Similar to many cancers, prostate cancer is caused by defects in the cancer's DNA, which are called genetic or genomic defects. New treatments targeting these defects are approved for metastatic castration-resistant prostate cancer. Specific new tests are under development to detect these potentially treatable genetic defects.

Patterns of practice of androgen deprivation therapy combined to radiotherapy in favorable and unfavorable intermediate risk prostate cancer. Results of The PROACT Survey from the French GETUG Radiation Oncology group

PURPOSE

The intermediate-risk (IR) prostate cancer (PCa) group is heterogeneous in terms of prognosis. For unfavorable or favorable IR PCa treated by radiotherapy, the optimal strategy remains to be defined. In routine practice, the physician's decision to propose hormonal therapy (HT) is controversial. The PROACT survey aimed to evaluate pattern and preferences of daily practice in France in this IR population.

MATERIALS AND METHODS

A web questionnaire was distributed to French radiotherapy members of 91 centers of the Groupe d'Etude des Tumeurs Uro-Genitales (GETUG). The questionnaire included four sections concerning: (i) the specialists who prescribe treatments and multidisciplinary decisions (MTD) validation; (ii) the definition of IR subsets of patients; (iii) radiotherapy parameters; (iv) the pattern of practice regarding cardiovascular (CV) and (iv) metabolic evaluation. A descriptive presentation of the results was used.

RESULTS

Among the 82 responses (90% of the centers), HT schedules and irradiation techniques were validated by specific board meetings in 54% and 45% of the centers, respectively. Three-fourths (76%) of the centers identified a subset of IR patients for a dedicated strategy. The majority of centers consider PSA>15 (77%) and/or Gleason 7 (4+3) (87%) for an unfavorable IR definition. Overall, 41% of the centers performed systematically a CV evaluation before HT prescription while 61% consider only CV history/status in defining the type of HT. LHRH agonists are more frequently prescribed in both favorable (70%) and unfavorable (98%) IR patients. Finally, weight (80%), metabolic profile (70%) and CV status (77%) of patients are considered for follow-up under HT.

CONCLUSION

To the best of our knowledge, this is the first survey on HT practice in IR PCa. The PROACT survey indicates that three-quarters of the respondents identify subsets of IR-patients in tailoring therapy. The CV status of the patient is considered in guiding the HT decision, its duration and type of drug.

Patient and caregiver benefit-risk preferences for nonmetastatic castration-resistant prostate cancer treatment

Background

Recently approved second‐generation androgen receptor inhibitors (SGARIs) for non‐metastatic castration‐resistant prostate cancer (nmCRPC) have similar efficacy but differ in safety profiles. We used a discrete choice experiment (DCE) to examine how nmCRPC patients and caregivers perceive the benefits versus risks of these new treatments.

Methods

An online DCE survey with 14 treatment choice questions was administered to nmCRPC patients and caregivers. Each choice question compared two hypothetical medication profiles varying in terms of 5 safety attributes (risk or severity of adverse events [AEs]: fatigue, skin rash, cognitive problems, serious fall, and serious fracture) and two efficacy attributes (duration of overall survival [OS] and time to pain progression). Random parameters logit models were used to estimate each attribute's relative importance. We also estimated the amounts of OS that respondents were willing to forego for a reduction in AEs.

Results

In total, 143 nmCRPC patients and 149 caregivers viewed the AEs in following order of importance (most to least): serious fracture, serious fall, cognitive problems, fatigue, and skin rash. On average, patients were willing to trade 5.8 and 4.0 months of OS to reduce the risk of serious fracture and fall, respectively, from 3% to 0%; caregivers were willing to trade 6.6 and 5.4 months of OS.

Conclusions

nmCRPC patients and caregivers preferred treatments with lower AE burdens and were willing to forego OS to reduce the risk and severity of AEs. Our results highlight the importance of carefully balancing risks and benefits when selecting treatments in this relatively asymptomatic population.

Physician preferences for non-metastatic castration-resistant prostate cancer treatment

BACKGROUND

Recent approvals of second-generation androgen receptor inhibitors (SGARIs) have changed the treatment landscape for non-metastatic castration-resistant prostate cancer (nmCRPC). These SGARIs have similar efficacy but differ in safety profiles. We used a discrete choice experiment to explore how United States physicians make treatment decisions between adverse events (AEs) and survival gains in nmCRPC, a largely asymptomatic disease.

METHODS

Treating physicians (n = 149) participated in an online survey that included 14 treatment choice questions, each comparing 2 hypothetical treatment profiles, which varied in terms of 5 safety and 2 efficacy attributes. We described safety attributes (fatigue, skin rash, cognitive problems, falls, and fractures) in terms of severity and frequency, and efficacy attributes (overall survival [OS] and time to pain progression) in terms of duration of effect. We used a random parameters logit model to estimate preference weights and importance scores for each attribute. We also estimated the amount of survival gain physicians were willing to trade for a reduction in specific AEs between treatment options.

RESULTS

Physicians placed more importance on survival than on time to pain progression, and viewed a reduction in cognitive problems from severe to none, a reduction in risk of a serious fracture from 8% to none, and a reduction in fatigue from severe to none as the most important safety attributes. Physicians were willing to forego 9.1 and 6.6 months of OS, respectively, to reduce cognitive problems and fatigue from severe to mild-to-moderate. To reduce the risk of a serious fracture from 8 to 5% and 5% to none, physicians were willing to trade 3.9 and 5.3 months of OS, respectively.

CONCLUSIONS

Physicians were willing to trade substantial amounts of survival to avoid AEs between hypothetical treatments. These results emphasize the importance of carefully balancing therapies' benefits and risks to ultimately optimize the overall quality of nmCRPC patients' survival. Nonetheless, it is noted that the results from the study sample of 149 physicans may not be representative of the viewpoints of all nmCRPC-treating physicians.

Blood platelet volume predicts treatment-specific outcomes of metastatic castration-resistant prostate cancer

BACKGROUND

In the present guidelines for the management of metastatic castration-resistant prostate cancer (mCRPC), it is unclear who benefits most from androgen receptor axis-targeted agents (ARATs) or docetaxel as the first-line treatment.

METHODS

We conducted a retrospective study to explore new treatment-specific biomarkers in mCRPC. A total of 211 patients with mCRPC who received either ARAT or docetaxel as first-line treatment were included. Patients were compared for radiographic progression and prostate-specific antigen (PSA) progression. Multivariable Cox regression models were used to assess the association between pretreatment biomarkers and risk of events. The statistical interaction between biomarkers and clinical outcomes was also evaluated.

RESULTS

Of all analyzed biomarkers, multivariable Cox regression models identified MPV [≤ median (9.7 fL)] as an independent prognostic factor of radiographic progression [hazard ratio (HR), 2.35; 95% confidence interval (CI), 1.15-4.80; P = 0.019] and PSA progression (HR, 1.96; 95% CI, 1.01-3.95; P = 0.048) in patients treated with ARAT, whereas such associations were not observed in those treated with docetaxel. Interaction analyses showed that those initially treated with docetaxel have lower risk of radiographic progression (HR, 0.33; 95% CI, 0.13-0.79; P = 0.014) and PSA progression (HR, 0.48; 95% CI, 0.23-0.98; P = 0.044) than ARAT when MPV was small.

CONCLUSIONS

The present study identified pretreatment MPV as a significant treatment-specific prognostic factor of PSA and radiographic progression in patients with mCRPC who received first-line treatment. Furthermore, our results suggested that those with small MPV may better be treated initially with docetaxel than ARAT.

Impact of taxanes on androgen receptor signaling

The development and progression of metastatic castration-resistant prostate cancer is the major challenge in the treatment of advanced prostate cancer. The androgen receptor signaling pathway remains active in metastatic castration-resistant prostate cancer. Docetaxel and cabazitaxel are the first- and second-line chemotherapy, respectively, for patients with metastatic castration-resistant prostate cancer. These two taxanes, in general, function by (i) inhibiting mitosis and inducing apoptosis and (ii) preventing microtubule-dependent cargo trafficking. In prostate cancer, taxanes have been reported to inhibit the nuclear translocation and activity of the androgen receptor. However, whether this is attainable or not clinically remains controversial. In this review, we will provide a comprehensive view of the effects of taxanes on androgen receptor signaling in prostate cancer.

Longitudinal model-based meta-analysis for survival probabilities in patients with castration-resistant prostate cancer

PURPOSE

The aims of this longitudinal model-based meta-analysis (MBMA) were to indirectly compare the time courses of survival probabilities and to identify corresponding potential significant covariates across approved drugs in patients with castration-resistant prostate cancer (CRPC).

METHODS

A systematic literature review for monotherapy studies in patients with CRPC was conducted up to August 8, 2018. The time courses of progression-free survival (PFS) and overall survival (OS) were fitted with parametric survival models. Covariate analyses were performed to determine the impact of treatment drugs, dosing regimens, and patient characteristics on the survival probabilities. Simulations were carried out to quantify the magnitude of covariate effects.

RESULTS

A total of 146 studies including clinical trials and real-world data on longitudinal survival probabilities in 20,712 patients with CRPC were included in our meta-database. The time courses of PFS and OS probabilities were best described by the log-logistic model. There was no significant difference in median OS and PFS between docetaxel, cabazitaxel, abiraterone acetate, and enzalutamide. There was no significant dose-response relationship in PFS or OS for docetaxel at 50 to 120 mg/m² every 3 weeks (Q3W) and cabazitaxel at 20 to 25 mg/m² Q3W. Model-based simulations indicated that PFS probability was associated with chemotherapy, Gleason score, and baseline prostate-specific antigen (BLPSA), while OS probability was associated with chemotherapy, Gleason score, visceral metastasis, Eastern Cooperative Oncology Group performance status, and BLPSA.

CONCLUSION

Our modeling and simulation framework can be applied to support indirect comparison, dose selection, and go/no-go decision-making for new agents targeting CRPC.

Deubiquitinating enzyme USP33 restrains docetaxel-induced apoptosis via stabilising the phosphatase DUSP1 in prostate cancer

The treatment of castration-resistant prostate cancer (CRPC) still faces many challenges. Docetaxel is a chemotherapeutic drug commonly used in CRPC patients. However, docetaxel-based chemotherapy usually causes docetaxel resistance, partially due to the resistance of CRPC cells to docetaxel-induced apoptosis. Here, we report that the deubiquitinating enzyme ubiquitin-specific protease 33 (USP33) inhibits docetaxel-induced apoptosis of prostate cancer cells, including androgen-independent prostate cancer cells. USP33 is overexpressed in prostate cancer cells and tissues. We found that knockdown or knockout of USP33 enhanced docetaxel-induced apoptosis of prostate cancer cells, accompanied by increased phosphorylation of the cJUN NH2-terminal kinase (JNK). After blocking docetaxel-induced JNK activation using the JNK inhibitor SP600125 or siRNA targeting JNK, the USP33 knockout-enhanced apoptosis was reversed. Furthermore, we found that USP33 could interact with the phosphatase DUSP1 to negatively regulate the activation of JNK, while USP33 knockdown promoted the proteasomal degradation of DUSP1. Mechanistically, we found that USP33 could inhibit the Lys48 (K48)-linked polyubiquitination of DUSP1. More importantly, DUSP1 overexpression could reverse the USP33 knockdown-induced JNK activation and apoptosis in docetaxel-treated prostate cancer cells. Therefore, USP33 overexpression in prostate cancer may contribute to docetaxel resistance by inhibiting the degradation of its partner DUSP1, leading to impaired JNK activation and apoptosis. Our study suggests that USP33-DUSP1-JNK may be a key signalling module mediating the docetaxel resistance of CRPC, indicating that USP33 is a potential novel therapeutic target in CRPC.

Efficacy of enzalutamide and apalutamide in the treatment of non-metastasic castration-resistant prostate cancer: Indirect comparison

OBJECTIVES

To perform an adjusted indirect comparison of the efficacy of enzalutamide and apalutamide in patients with non-metastatic castration-resistant prostate cancer (nmCRPC) with a high risk of progression to metastatic disease.

MATERIAL AND METHODS

After carrying out a literature search, we performed an adjusted indirect comparison (Bucher et al.) of the relative efficacy of enzalutamide and apalutamide in patients with nmCRPC with a high risk of progression to metastatic disease. The outcomes included were metastasis-free survival (MFS) and PSA response rate (PSARR).

RESULTS

There were no statistically significant differences between enzalutamide and apalutamide regarding the analysed outcomes. For the comparison enzalutamide+ADT vs. apalutamide+ADT: MFS a HR (95% CI)=1,036 (0.781-1.373) was obtained. For PSARR, a RR (95% CI)=0.81 (0.339-1.938) was obtained.

CONCLUSIONS

The adjusted indirect comparison performed in this study shows that there are no statistically significant differences in terms of efficacy regarding MFS and PSARR between enzalutamide+ADT and apalutamide+ADT in patients with nmCRPC with a high risk of progression to metastatic disease. However, in order to confirm these results, an independent trial with direct comparison between both drugs would be required.

Androgen Receptor-Activated Enhancers Simultaneously Regulate Oncogene TMPRSS2 and lncRNA PRCAT38 in Prostate Cancer

Prostate cancer is a common carcinoma in males, the development of which involves the androgen receptor (AR) as a key regulator. AR transactivation induces the high expression of androgen-regulated genes, including transmembrane protease serine 2 (TMPRSS2) and long noncoding RNA prostate cancer-associated transcript 38 (PRCAT38). PRCAT38 and TMPRSS2 are both located on chromosome 21, separated by a series of enhancers. PRCAT38 is a prostate-specific long noncoding RNA that is highly expressed in cancer tissue as compared to normal tissue. Here, we show chromatin looping by enhancers E1 and E2 with the promoters for PRCAT38 and TMPRSS2, indicating the co-regulation of PRCAT38 and TMPRSS2 by the same enhancers. The knockout of enhancer E1 or E2 simultaneously impaired the transcription of PRCAT38 and TMPRSS2 and inhibited cell growth and migration. Moreover, the loop formation and enhancer activity were mediated by AR/FOXA1 binding and the activity of acetyltransferase p300. Our findings demonstrate the utilization of shared enhancers in the joint regulation of two oncogenes in prostate cancer cells.

Clinical characteristics, treatment pattern, and medical costs associated with metastatic castration-resistant prostate cancer in Chinese tertiary care hospital settings

Objectives: To describe the clinical characteristics, treatment pattern, and medical costs associated with metastatic castration-resistant prostate cancer (mCRPC) in Chinese patients. Methods: This retrospective study identified a group of patients with newly-developed mCRPC from 2012 to 2016 to extract information from their medical and billing records in two tertiary care hospitals. Descriptive statistical methods were used to summarize patient clinical characteristics, treatment pattern, and monthly medical costs. Conventional regression analyses explored the predictors for the utilization of chemotherapy and monthly medical costs. Results: Seventy-eight identified mCRPC patients were characterized with a high proportion of stage IV tumors at diagnosis of prostate cancer (75.0%) and high prevalence of bone metastasis (91.0%). Sixty-six percent of the identified patients only received one treatment episode. Among the patients receiving the first treatment episode, hormone therapy, chemotherapy, and best supportive care (BSC) accounted for 75.7%, 21.4%, and 2.9%, respectively; the previous orchiectomy was significantly associated with chemotherapy (odds ratio = 5.325, p = 0.034); and chemotherapy was associated with comparable drug costs and higher non-drug costs (coefficient = 0.657, p = 0.056) when compared to hormone therapy after the adjustment of patient characteristics. Conclusions: Chinese mCRPC patients were characterized with delayed diagnosis of prostate cancer and high prevalence of bone metastasis. The treatment options for mCRPC were limited in Chinese patients as the conventional hormone therapy was still heavily used after the development of mCRPC. The medical costs associated with mCRPC were mainly driven by chemotherapy in Chinese patients.

Androgen Receptor Signaling in Castration-Resistant Prostate Cancer Alters Hyperpolarized Pyruvate to Lactate Conversion and Lactate Levels In Vivo

PURPOSE

Androgen receptor (AR) signaling affects prostate cancer (PCa) growth, metabolism, and progression. Often, PCa progresses from androgen-sensitive to castration-resistant prostate cancer (CRPC) following androgen-deprivation therapy. Clinicopathologic and genomic characterizations of CRPC tumors lead to subdividing CRPC into two subtypes: (1) AR-dependent CRPC containing dysregulation of AR signaling alterations in AR such as amplification, point mutations, and/or generation of splice variants in the AR gene; and (2) an aggressive variant PCa (AVPC) subtype that is phenotypically similar to small cell prostate cancer and is defined by chemotherapy sensitivity, gain of neuroendocrine or pro-neural marker expression, loss of AR expression, and combined alterations of PTEN, TP53, and RB1 tumor suppressors. Previously, we reported patient-derived xenograft (PDX) animal models that contain characteristics of these CRPC subtypes. In this study, we have employed the PDX models to test metabolic alterations in the CRPC subtypes.

PROCEDURES

Mass spectrometry and nuclear magnetic resonance analysis along with in vivo hyperpolarized 1-[¹³C]pyruvate spectroscopy experiments were performed on prostate PDX animal models.

RESULTS

Using hyperpolarized 1-[¹³C]pyruvate conversion to 1-[¹³C]lactate in vivo as well as lactate measurements ex vivo, we have found increased lactate production in AR-dependent CRPC PDX models even under low-hormone levels (castrated mouse) compared to AR-negative AVPC PDX models.

CONCLUSIONS

Our analysis underscores the potential of hyperpolarized metabolic imaging in determining the underlying biology and in vivo phenotyping of CRPC.

Patient and Provider Variables Associated with Variation in the Systemic Treatment of Advanced Prostate Cancer

Purpose

Six treatments have improved overall survival in men with metastatic castration-resistant prostate cancer (mCRPC), each differing in toxicities and cost. This study identified patient and provider factors associated with variation in treatment of men with mCRPC to identify potential barriers to treatments.

Methods

A claims database of commercially insured patients was used to identify patients with prostate cancer treated with abiraterone, enzalutamide, docetaxel, cabazitaxel, sipuleucel-T, or radium-223 between 2010 and 2016. Multinomial and binomial logistic regressions were conducted to determine patient and provider factors associated with treatment patterns.

Results

Among 5,575 patients identified, patients with a household income >$99,000 were less likely to receive an expensive oral androgen signaling inhibitor (abiraterone or enzalutamide) as first-line treatment versus docetaxel compared to patients with a household income <$50,000 (odds ratio, OR, 0.66, 95% confidence interval, CI, 0.48-0.92). Patients who are Black (OR 1.43, 95% CI 1.02-2.01), live in the Pacific region versus the South Atlantic (OR 2.68, 95% CI 1.74-4.11), received treatment from a urologist versus a medical oncologist (OR 16.05, 95% CI 6.01-42.86), or had pre-existing heart failure (OR 1.69, 95% CI 1.18-2.42) were more likely to receive first-line oral androgen signaling inhibitors over docetaxel, independent of other factors on multivariable analysis.

Conclusion

Clinicians and policy makers should be aware of the potential barriers and provider factors that influence use of novel therapies among patients with advanced prostate cancer, including the paradoxical effect of income and the substantial effect of provider specialty on first-line treatment rendered to patients with mCRPC.

Automated Definition of Skeletal Disease Burden in Metastatic Prostate Carcinoma: A 3D Analysis of SPECT/CT Images

To meet the current need for skeletal tumor-load estimation in castration-resistant prostate cancer (CRPC), we developed a novel approach based on adaptive bone segmentation. In this study, we compared the program output with existing estimates and with the radiological outcome. Seventy-six whole-body single-photon emission computed tomographies/x-ray computed tomography with 3,3-diphosphono-1,2-propanedicarboxylic acid from mCRPC patients were analyzed. The software identified the whole skeletal volume (S_Vol) and classified the voxels metastases (M_Vol) or normal bone (B_Vol). S_Vol was compared with the estimation of a commercial software. M_Vol was compared with manual assessment and with prostate specific antigen (PSA) levels. Counts/voxel were extracted from M_Vol and B_Vol. After six cycles of ²²³RaCl2-therapy every patient was re-evaluated as having progressive disease (PD), stable disease (SD), or a partial response (PR). S_Vol correlated with that of the commercial software (R = 0.99, p < 0.001). M_Vol correlated with the manually-counted lesions (R = 0.61, p < 0.001) and PSA (R = 0.46, p < 0.01). PD had a lower counts/voxel in M_Vol than PR/SD (715 ± 190 vs. 975 ± 215 and 1058 ± 255, p < 0.05 and p < 0.01) and B_Vol (PD 275 ± 60, PR 515 ± 188 and SD 528 ± 162 counts/voxel, p < 0.001). Segmentation-based tumor load correlated with radiological/laboratory indices. Uptake was linked with the clinical outcome, suggesting that metastases in PD patients have a lower affinity for bone-seeking radionuclides and might benefit less from bone-targeted radioisotope therapies.

Prostate carcinoma cell-derived exosomal MicroRNA-26a modulates the metastasis and tumor growth of prostate carcinoma

Prostate carcinoma may develop into metastatic castration-resistant prostate carcinoma (mCRPC) after endocrine therapy. Exosomal microRNAs play an important role in the regulation of tumor microenvironment. Our study aimed to investigate the effect of exosomal miR-26a on tumor phenotype of prostate carcinoma. Low-grade prostate carcinoma cell line (LNCAP) and mCRPC cell line (PC-3) were treated as experimental subjects according to their miR-26a expressions. Wound healing, transwell and colony-forming unit assays were performed after miR-26a mimic/inhibitor transfection. Then, exosomes were isolated from LNCAP and PC-3 cells, and the levels of exosomal miR-26a were determined. After co-culture of LNCAP (PC-3) cells with PC-3 (LNCAP) exosomes, changes in malignant behaviors were measured. Moreover, LNCAP/PC-3 exosomes were injected into xenograft tumor mice to determine effects of the exosomes on tumorigenicity of LNCAP and PC-3 cells. MiR-26a showed a potently inhibitory effect on cell proliferation, migration and invasion of LNCAP and PC-3 cells. LNCAP exosomes had a higher miR-26a level, compared with PC-3 exosomes. Overexpression of miR-26a attenuated the enhanced malignant behavior of LNCAP cells induced by PC-3 exosomes, and miR-26a inhibition could reverse the inhibitory effects of LNCAP exosomes on PC-3 cells. Exosomal miR-26a could significantly alter the expressions of epithelial-mesenchymal transition (EMT)-related factors. Moreover, LNCAP exosomes suppressed the tumorigenicity of PC-3 cells, while PC-3 exosomes could promote the tumorigenicity of LNCAP cells. Our data suggest that exosomal miR-26a derived from prostate carcinoma cells had a suppressive effect on the metastasis and tumor growth of prostate carcinoma.

No evidence of association between psychological distress and pain relief in patients with bone metastases from castration-resistant prostate cancer treated with 223Radium

OBJECTIVE

Painful bone metastases cause reduced quality of life (QoL) in patients with castration-resistant prostate cancer (CRPC). Alpha-emitter 223Radium is associated with a clear survival benefit and significant bone pain palliation in CRPC patients with symptomatic bone metastases. The aim of this study was to evaluate the association between pain relief and psychological distress during the time course of therapy in patients treated with 223Radium.

METHODS

A total of 63 patients with mCRPC undergoing 223Radium treatment in our Nuclear Medicine Unit, carefully instructed on the possibility of improving the pain and increasing the survival by the treatment, were retrospectively evaluated. Pain response during treatment was assessed with the Brief Pain Inventory Numeric Rating Scale. Psychological distress was evaluated through the analysis of specific items from EORTC QoL questionnaires C30 and BM22, submitted to patients at baseline and after each 223Radium cycle.

RESULTS

Pain intensity showed a significant decrease after first 223Radium administration (-1.03 points, p = 0.0032), with a subsequent stability through the course of treatment (-1.30 points, p = <0.001). Psychological status did not show significant variations during 223Radium treatment, and no association was found between psychological status and pain relief in our population.

CONCLUSIONS

In our experience, bone pain palliation provided by 223Radium do not correlate with an improved psychological status in patients with advanced PC. This observation emphasises the role of the psychological aspect in the evaluation of the QoL and the necessity of a multidisciplinary approach in which the emotional aspect of the patient is carefully evaluated.

Patient-reported outcomes following enzalutamide or placebo in men with non-metastatic, castration-resistant prostate cancer (PROSPER): a multicentre, randomised, double-blind, phase 3 trial

BACKGROUND

In the PROSPER trial, enzalutamide significantly improved metastasis-free survival in patients with non-metastatic, castration-resistant prostate cancer. Here, we report the results of patient-reported outcomes of this study.

METHODS

In the randomised, double-blind, placebo-controlled, phase 3 PROSPER trial, done at 254 study sites worldwide, patients aged 18 years or older with non-metastatic, castration-resistant prostate cancer and a prostate-specific antigen doubling time of up to 10 months were randomly assigned (2:1) via an interactive voice web recognition system to receive oral enzalutamide (160 mg per day) or placebo. Randomisation was stratified by prostate-specific antigen doubling time and baseline use of a bone-targeting agent. The primary endpoint was metastasis-free survival, reported elsewhere. Secondary efficacy endpoints, reported here, were pain progression (assessed by the Brief Pain Inventory Short Form [BPI-SF] questionnaire) and health-related quality of life (assessed with the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire [EORTC QLQ-PR25], the EuroQoL 5-Dimensions 5-Levels health questionnaire visual analogue scale [EQ-5D-FL, EQ-VAS], and the Functional Assessment of Cancer Therapy-Prostate [FACT-P] questionnaires). Patients completed questionnaires at baseline, week 17, and every 16 weeks thereafter until treatment discontinuation. We used predefined questionnaire thresholds to identify clinically meaningful changes. Enrolment for PROSPER is complete and follow-up continues. This trial is registered with ClinicalTrials.gov, number NCT02003924.

FINDINGS

Between Nov 26, 2013, and June 28, 2017, 1401 patients were enrolled and randomly assigned to receive enzalutamide (n=933) or placebo (n=468). Median follow-up was 18·5 months (IQR 10·7-29·2) in the enzalutamide group and 15·1 months (7·4-25·9) in the placebo group. Patient-reported outcome scores at baseline were similar between groups. Changes in least squares mean from baseline to week 97 favoured enzalutamide versus placebo for FACT-P social and family wellbeing (0·30 [95% CI -0·25 to 0·85] vs -0·64 [-1·51 to 0·24]; difference 0·94 [95% CI 0·02 to 1·85]; p=0·045) and disfavoured enzalutamide versus placebo for EORTC QLQ-PR25 hormonal treatment-related symptoms (1·55 [0·26 to 2·83) vs -1·83 [-3·86 to 0·20]; difference 3·38 [1·24 to 5·51]; p=0·0020); neither of these changes were clinically meaningful. No significant differences were observed between treatments for changes from baseline to week 97 in any other patient-reported outcome score. Time to clinically meaningful pain progression as assessed by BPI-SF pain severity was longer with enzalutamide than with placebo (median 36·83 months, [95% CI 34·69 to not reached [NR] vs NR; hazard ratio [HR] 0·75 [95% CI 0·57 to 0·97]; p=0·028); there was no significant difference for BPI-SF item 3 or pain interference. Time to clinically meaningful symptom worsening was longer with enzalutamide than with placebo for EORTC QLQ-PR25 urinary symptoms (median 36·86 months [95% CI 33·35 to NR] vs 25·86 [18·53 to 29·47]; HR 0·58 [95% CI 0·46 to 0·72]; p<0·0001) and bowel symptoms (33·15 [29·50 to NR] vs 25·89 [18·43 to 29·67]; 0·72 [0·59 to 0·89]; p=0·0018), and clinically meaningful health-related quality of life as assessed by FACT-P total score (22·11 [18·63 to 25·86] vs 18·43 [14·85-19·35]; 0·83 [0·69 to 0·99]; p=0·037), emotional wellbeing (36·73 [33·12 to 38·21] vs 29·47 [22·18 to 33·15]; 0·69 [0·55 to 0·86]; p=0·0008), and prostate cancer subscale (18·43 [14·85 to 18·66] vs 14·69 [11·07 to 16·20]; 0·79 [0·67 to 0·93]; p=0·0042), although there was no significant difference for other FACT-P scores. Time to clinically meaningful deterioration in EORTC QLQ-PR25 hormonal treatment-related symptoms was shorter with enzalutamide than with placebo (median 33·15 months [95% CI 29·60 to NR] vs 36·83 [29·47 to NR]; HR 1·29 [95% CI 1·02 to 1·63]; p=0·035). Time to deterioration of EQ-VAS was significantly longer for enzalutamide than for placebo (median 22·11 months [95% CI 18·46 to 25·66] vs 14·75 [11·07 to 18·17]; HR 0·75 [95% CI 0·63 to 0·90]; p=0·0013).

INTERPRETATION

Patients with non-metastatic, castration-resistant prostate cancer receiving enzalutamide had longer metastasis-free survival than did those who received placebo, while maintaining low pain levels and prostate cancer symptom burden and high health-related quality of life. Enzalutamide showed a clinical benefit by delaying pain progression, symptom worsening, and decrease in functional status, compared with placebo. These findings suggest that enzalutamide is a treatment option that should be discussed with patients presenting with high-risk, non- metastatic, castration-resistant prostate cancer.

FUNDING

Astellas Pharma Inc, Medivation LLC (a Pfizer Company).

177Lu-PSMA-617 Radioligand Therapy in Metastatic Castration-Resistant Prostate Cancer Patients with a Single Functioning Kidney

The aim of this study was to assess the safety, tolerability, and effects on renal function as well as therapeutic efficacy of prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (PRLT) using ¹⁷⁷Lu-labeled PSMA-617 in patients with metastatic castration-resistant prostate cancer and a single functioning kidney before PRLT. Methods: Sixteen patients (aged 53-78 y; mean age, 64.7 ± 6.5 y) with a single functioning kidney received PRLT with ¹⁷⁷Lu-PSMA-617 between March 2015 and October 2018. All parameters of renal function (serum creatinine, blood urea nitrogen, and electrolytes) were prospectively documented in a structured database and analyzed before each PRLT cycle and in follow-up. Renal function was further quantified by measuring tubular extraction rate (TER) using ^99mTc-mercaptoacetyltriglycine renal scintigraphy. Treatment-related adverse events were graded according to the Common Terminology Criteria for Adverse Events (CTCAE), version 5.0. Kaplan-Meier analysis was performed to obtain the progression-free survival and overall survival. Results: The median administered activity was 22.1 GBq (range, 15.4-33.8 GBq). The calculated absorbed radiation dose to the kidney per cycle was 5.3 ± 2.1 Gy (0.81 ± 0.32 Gy/GBq). Renal function was already impaired at baseline in 43.7% of patients, including CTCAE grade 1 renal impairment in 25.0% and CTCAE grade 2 in 18.8%. Grade 1 and 2 renal impairment, respectively, were present in 37.5% and 6.3% of the patients after the first PRLT cycle and in 31.3% and 12.5% after the second cycle. No CTCAE grade 3 or 4 nephrotoxicity was observed during or after treatment. There was no significant change in either TER or the ratio of TER to lower-limit TER after the last cycle of treatment (P > 0.05). The median PFS was 8.1 mo based on both the criteria of the European Organization for Research and Treatment of Cancer and RECIST. The median overall survival has yet to be reached with a median follow-up time of 19.3 mo (range, 5.8-45.3 mo). Conclusion: In patients with a single functioning kidney, ¹⁷⁷Lu-PSMA-617 PRLT is feasible, seems to be effective, and is well tolerated, without any signs of acute or subacute nephrotoxicity during a mean follow-up of nearly 2 y (and up to 45.3 mo). Further long-term follow-up of this special patient group is warranted.

Evaluation of Treatment Patterns and Costs in Patients with Prostate Cancer and Bone Metastases

BACKGROUND

There are a lack of guideline recommendations for patients with metastatic castration-resistant prostate cancer (mCRPC) undergoing treatment progression and sequencing. Understanding treatment patterns and associated utilization and costs may help inform stakeholders and guide decision making.

OBJECTIVE

To describe treatment patterns and health care costs in prostate cancer (PC) patients with bone metastases treated with agents approved by the FDA for mCRPC.

METHODS

2 large integrated claims databases (MarketScan and PharMetrics) were used to identify males aged ≥ 18 years who were diagnosed and treated for PC (ICD-9-CM code 185.xx or 233.4) with bone metastases (ICD-9-CM code 198.5) from June 2013 to September 2014. Patients were required to be continuously enrolled for ≥ 6 months before and after initiation of treatment with abiraterone, cabazitaxel, docetaxel, enzalutamide, mitoxantrone, radium-223, sipuleucel-T, or other chemotherapy. Study endpoints included lines of therapy, health care resource utilization per patient per month (PPPM), PPPM costs, and mortality rate. Descriptive analysis was completed for the study sample, and survival function was calculated via Kaplan-Meier estimates.

RESULTS

There were 953 patients meeting all inclusion criteria in the MarketScan database and 565 patients in the PharMetrics database. The median follow-up time was 18 months (interquartile range [IQR] = 14-23) for MarketScan and 14 months (IQR = 11-18) for PharMetrics. Mean age (SD) was 71 (± 10.7) and 66 (± 9.3) years, respectively. Before mCRPC treatment initiation, patients received palliative radiation therapy and bone antiresorptive therapy. For MarketScan and PharMetrics, respectively, 14.0% and 18.2% of patients received radiation therapy, 36.1% and 40.0% received denosumab; 16.5% and 16.8% received zoledronic acid; and 0.2% and 0.8% received pamidronate. Across both databases, abiraterone was the most commonly received bone metastasis treatment agent across all lines of therapy, except fourth line. Radium-223, cabazitaxel, and mitoxantrone were the least utilized therapies. The median cost PPPM during the post-index period was $10,916 (IQR=$5,334-$13,457) in MarketScan and $10,292 (IQR = $7,245-$14,699) in PharMetrics. The cost PPPM during the 6-month pre-index period was $2,643 (IQR = $850-$4,357) in MarketScan and $2,742 (IQR = $1,484-$4,730) in PharMetrics.

CONCLUSIONS

Patients were treated mainly with abiraterone across most lines of care, with radium-223, cabazitaxel, and mitoxantrone as the least utilized therapies. Median costs PPPM increased by approximately $8,900 after initiation of FDA-approved agents for mCRPC, with the largest increase in cost stemming from oral medications.

DISCLOSURES

Funding for this study was provided by Bayer HealthCare Pharmaceuticals. All authors were employees at Bayer HealthCare Pharmaceuticals at the time this study was conducted. This study was presented as a poster at the 2017 American Society of Clinical Oncology (ASCO) Genitourinary Cancers Symposium; February 16-18, 2017; Orlando, FL.

Cabazitaxel inhibits prostate cancer cell growth by inhibition of androgen receptor and heat shock protein expression

PURPOSE

Cabazitaxel, a semi-synthetic taxane of the third generation, inhibits prostate cancer (PC) cell growth by affecting the microtubule architecture. Since cabazitaxel has also been demonstrated to inhibit androgen receptor (AR) functionality, AR and AR-associated heat shock protein (HSP) expressions in the presence of cabazitaxel were characterized.

METHODS

AR and HSP expressions were assessed via Western blotting utilizing a PC-cell-line in vitro system incubated with cabazitaxel.

RESULTS

Incubation experiments with 0.3 nM cabazitaxel exhibited significantly reduced levels of AR and the AR-associated factors HSP90α, HSP40, and HSP70/HSP90 organising protein. Furthermore, expression of the anti-apoptotic factor HSP60 was suppressed. In contrast to other anticancer compounds, cabazitaxel did not alter the cytoprotective chemoresistance factor HSP27.

CONCLUSIONS

Despite the deregulation of microtubule organisation, cabazitaxel has been shown to suppress the expression of HSP. Very notably, and may be as a result of down-regulated HSP, cabazitaxel additionally inhibits the expression of the AR in AR-positive PC cells. Thus, cabazitaxel bears an additional anti-proliferative activity which is at least in part specific for PC cells.

Wnt/Beta-Catenin Signaling and Prostate Cancer Therapy Resistance

Metastatic or locally advanced prostate cancer (PCa) is typically treated with androgen deprivation therapy (ADT). Initially, PCa responds to the treatment and regresses. However, PCa almost always develops resistance to androgen deprivation and progresses to castrate-resistant prostate cancer (CRPCa), a currently incurable form of PCa. Wnt/β-Catenin signaling is frequently activated in late stage PCa and contributes to the development of therapy resistance. Although activating mutations in the Wnt/β-Catenin pathway are not common in primary PCa, this signaling cascade can be activated through other mechanisms in late stage PCa, including cross talk with other signaling pathways, growth factors and cytokines produced by the damaged tumor microenvironment, release of the co-activator β-Catenin from sequestration after inhibition of androgen receptor (AR) signaling, altered expression of Wnt ligands and factors that modulate the Wnt signaling, and therapy-induced cellular senescence. Research from genetically engineered mouse models indicates that activation of Wnt/β-Catenin signaling in the prostate is oncogenic, enables castrate-resistant PCa growth, induces an epithelial-to-mesenchymal transition (EMT), promotes neuroendocrine (NE) differentiation, and confers stem cell-like features to PCa cells. These important roles of Wnt/β-Catenin signaling in PCa progression underscore the need for the development of drugs targeting this pathway to treat therapy-resistant PCa.

Cost-effectiveness analyses and cost analyses in castration-resistant prostate cancer: A systematic review

Background

Treatment of metastatic prostate cancer is associated with high personal and economic burden. Recently, new treatment options for castration-resistant prostate cancer became available with promising survival advantages. However, cost-effectiveness of those new treatment options is sometimes ambiguous or given only under certain circumstances. The aim of this study was to systematically review studies on the cost-effectiveness of treatments and costs of castration-resistant prostate cancer (CRPC) and metastasizing castration-resistant prostate cancer (mCRPC) on their methodological quality and the risk of bias.

Methods

A systematic literature search was performed in the databases PubMed, CINAHL Complete, the Cochrane Library and Web of Science Core Collection for costs-effectiveness analyses, model-based economic evaluations, cost-of-illness analyses and budget impact analyses. Reported costs were inflated to 2015 US$ purchasing power parities. Quality assessment and risk of bias assessment was performed using the Consolidated Health Economic Evaluation Reporting Standards checklist and the Bias in Economic Evaluations checklist, respectively.

Results

In total, 38 articles were identified by the systematic literature search. The methodological quality of the included studies varied widely, and there was considerable risk of bias. The cost-effectiveness treatments for CRPC and mCRPC was assessed with incremental cost-effectiveness ratios ranging from dominance for mitoxantrone to $562,328 per quality-adjusted life year gained for sipuleucel-T compared with prednisone alone. Annual costs for the treatment of castration-resistant prostate cancer ranged from $3,067 to $77,725.

Conclusion

The cost-effectiveness of treatments of CRPC strongly depended on the willingness to pay per quality-adjusted life year gained/life-year saved throughout all included costs-effectiveness analyses and model-based economic evaluations. High-quality cost-effectiveness analyses based on randomized controlled trials are needed in order to make informed decisions on the management of castration-resistant prostate cancer and the resulting financial impact on the healthcare system.

Current strategies for targeting the activity of androgen receptor variants

Current therapies for advanced prostate cancer, such as enzalutamide and abiraterone, focus on inhibiting androgen receptor (AR) activity and reducing downstream signaling pathways to inhibit tumor growth. Unfortunately, cancer cells are very adaptable and, over time, these cells develop mechanisms by which they can circumvent therapeutics. One of the many mechanisms that have been discovered is the generation of AR variants. These variants are generated through alternative splicing of the full length AR and often lack the ligand binding domain. This leads to forms of the AR that are constitutively active that continue to promote prostate cancer cell growth even in the absence of ligand. The high prevalence of AR variants and their role in disease progression have prompted a number of studies investigating ways to inhibited AR variant expression and activity. Among these are the anti-helminthic drug, niclosamide, which selectively promotes degradation of AR variants over full length AR and re-sensitizes anti-androgen resistant prostate cancer cells to treatment with enzalutamide and abiraterone. Other AR variant targeting mechanisms include interfering with AR variant co-activators and the development of drugs that bind to the DNA or N-terminal AR domains, which are retained in most AR variants. The clinical efficacy of treating prostate cancer by targeting AR variants is under investigation in several clinical trials. In this review, we provide an overview of the most relevant AR variants and discuss current AR variant targeting strategies.