Targeting continued androgen receptor signaling in prostate cancer

The pleiotropic nature of NONO, a master regulator of essential biological pathways in cancers

NONO is a member of the Drosophila behavior/human splicing (DBHS) family of proteins. NONO is a multifunctional protein that acts as a "molecular scaffold" to carry out versatile biological activities in many aspects of gene regulation, cell proliferation, apoptosis, migration, DNA damage repair, and maintaining cellular circadian rhythm coupled to the cell cycle. Besides these physiological activities, emerging evidence strongly indicates that NONO-altered expression levels promote tumorigenesis. In addition, NONO can undergo various post-transcriptional or post-translational modifications, including alternative splicing, phosphorylation, methylation, and acetylation, whose impact on cancer remains largely to be elucidated. Overall, altered NONO expression and/or activities are a common feature in cancer. This review provides an integrated scenario of the current understanding of the molecular mechanisms and the biological processes affected by NONO in different tumor contexts, suggesting that a better elucidation of the pleiotropic functions of NONO in physiology and tumorigenesis will make it a potential therapeutic target in cancer. In this respect, due to the complex landscape of NONO activities and interactions, we highlight caveats that must be considered during experimental planning and data interpretation of NONO studies.

Understanding the molecular regulators of neuroendocrine prostate cancer

Worldwide, prostate cancer (PCa) remains a leading cause of death in men. Histologically, the majority of PCa cases are classified as adenocarcinomas, which are mainly composed of androgen receptor-positive luminal cells. PCa is initially driven by the androgen receptor axis, where androgen-mediated activation of the receptor is one of the primary culprits for disease progression. Therefore, in advanced stage PCa, patients are generally treated with androgen deprivation therapies alone or in combination with androgen receptor pathway inhibitors. However, after an initial decrease, the cancer recurs for majority patients. At this stage, cancer is known as castration-resistant prostate cancer (CRPC). Majority of CRPC tumors still depend on androgen receptor axis for its progression to metastasis. However, in around 20-30% of cases, CRPC progresses via an androgen receptor-independent pathway and is often presented as neuroendocrine cancer (NE). This NE phenotype is highly aggressive with poor overall survival as compared to CRPC adenocarcinoma. NE cancers are resistant to standard taxane chemotherapies, which are often used to treat metastatic disease. Pathologically and morphologically, NE cancers are highly diverse and often co-exist with adenocarcinoma. Due to the lack of proper biomarkers, it is often difficult to make an early diagnosis of this lethal disease. Moreover, increased tumor heterogeneity and admixtures of adeno and NE subtypes in the same tumor make early detection of NE tumors very difficult. With the advancement of our knowledge and sequencing technology, we are now able to better understand the molecular mediators of this transformation pathway. This current study will give an update on how various molecular regulators are involved in these lineage transformation processes and what challenges we are still facing to detect and treat this cancer.

Survivin-targeted nanomedicine for increased potency of abiraterone and enzalutamide against prostate cancer

Prostate cancer is the leading and most aggressive cancer around the world, several therapeutic approaches have emerged but none have achieved the satisfactory result. However, these therapeutic approaches face many challenges related to their delivery to target cells, including their in vivo decay, the limited uptake by target cells, the requirements for nuclear penetration (in some cases), and the damage caused to healthy cells. These barriers can be avoided by effective, targeted, combinatorial approaches, with minimal side effects, which are being investigated for the treatment of cancer. Here, we developed a combinatorial nanomedicine comprising abiraterone and enzalutamide bioconjugated survivin-encapsulated gold nanoparticles (AbEzSvGNPs) for targeted therapy of prostate cancer. AbEzSvGNPs were characterized by different biophysical techniques such as UV visible spectroscopy, dynamic light scattering, zeta potential, transmission electron microscope, and Fourier transform infrared spectroscopy. Interestingly, the effect of abiraterone, enzalutamide and surviving encapsulated gold nanoparticles was found to be synergistic in nature in AbEzSvGNPs against DU 145 (IC50 = 4.21 µM) and PC-3 (IC50 = 5.58 µM) cells and their potential was observed to be greatly enhanced as compared with the combined effect of the drugs (abiraterone and enzalutamide) in their free form. Furthermore, AbEzSvGNPs were found to be highly safe and did not exhibit significant cytotoxicity against normal rat kidney cells. The observed effects of AbEzSvGNPs involved the modulation of different signaling pathways in prostate cancer cells. This delivery system employed non-androgen receptor-dependent delivery of abiraterone and enzalutamide. The anionic AbEzSvGNPs delivered abiraterone and enzalutamide unaltered into the nucleus through caveolae mediated internalization to act nonspecifically on DNA; internalization of the anionic nanoparticles into the cytoplasm was also observed via other routes. AbEzSvGNPs synthesized and evaluated in this study are promising candidates for prostate cancer therapy.

Novel Insights into the Role of the Antioxidants in Prostate Pathology

To date, it is known that antioxidants protect cells from damage caused by oxidative stress and associated with pathological conditions. Several studies have established that inflammation is a state that anticipates the neoplastic transformation of the prostate. Although many experimental and clinical data have indicated the efficacy of antioxidants in preventing this form of cancer, the discrepant results, especially from recent large-scale randomized clinical trials, make it difficult to establish a real role for antioxidants in prostate tumor. Despite these concerns, clinical efficacy and safety data show that some antioxidants still hold promise for prostate cancer chemoprevention. Although more studies are needed, in this review, we briefly describe the most common antioxidants that have shown benefits in preclinical and clinical settings, focusing our attention on synthesizing the advances made so far in prostate cancer chemoprevention using antioxidants as interesting molecules for the challenges of future therapies.

Establishment of a five-enzalutamide-resistance-related-gene-based classifier for recurrence-free survival predicting of prostate cancer

To identify prostate cancer (PCa) patients with a high risk of recurrence is critical before delivering adjuvant treatment. We developed a classifier based on the Enzalutamide treatment resistance‐related genes to assist the currently available staging system in predicting the recurrence‐free survival (RFS) prognosis of PCa patients. We overlapped the DEGs from two datasets to obtain a more convincing Enzalutamide‐resistance‐related‐gene (ERRG) cluster. The five‐ERRG‐based classifier obtained good predictive values in both the training and validation cohorts. The classifier precisely predicted RFS of patients in four cohorts, independent of patient age, pathological tumour stage, Gleason score and PSA levels. The classifier and the clinicopathological factors were combined to construct a nomogram, which had an increased predictive accuracy than that of each variable alone. Besides, we also compared the differences between high‐ and low‐risk subgroups and found their differences were enriched in cancer progression‐related pathways. The five‐ERRG‐based classifier is a practical and reliable predictor, which adds value to the existing staging system for predicting the RFS prognosis of PCa after radical prostatectomy, enabling physicians to make more informed treatment decisions concerning adjuvant therapy.

The Overall Survival and Safety of Men with Metastatic Hormone-Sensitive Prostate Cancer Treated with Combination Therapy of Novel Androgen Receptor Antagonists and Androgen-Deprivation Therapy: A Systematic Review and Meta-Analysis

Background

Several novel androgen receptor antagonists have been introduced into the treatment of metastatic hormone-sensitive prostate cancer (mHSPC). We conducted a meta-analysis to evaluate the survival and safety of the combination therapy of novel androgen receptor antagonist and androgen-deprivation therapy (ADT) in patients with mHSPC.

Methods

Electronic databases were searched for randomized controlled trials (RCTs) of ADT combined with novel androgen receptor antagonists compared with ADT alone in men with mHSPC. Revman 5.4 and STATA 14.0 were used to performed the meta-analysis, and hazard ratio (HR) and odds ratio (OR) with 95% confidence intervals (CIs) were used as the measurement indicators of outcome variables.

Results

Six RCTs were eventually identified for meta-analysis. Compared with ADT alone, the combination therapy of novel androgen receptor antagonists and ADT can significantly improve the overall survival (OS) and progression-free survival (PFS), as the pooled HR were 0.66, 95%CI (0.60, 0.72), P < 0.00001 and 0.43, 95%CI (0.34, 0.54), P < 0.00001, respectively, despite increasing the risk of any serious adverse events (OR: 1.18, 95%CI (1.04, 1.33), P=0.008). Discussion. This study showed that compared with ADT alone, the combination therapy of novel androgen receptor antagonists and ADT can significantly improve the survival status of mHSPC patients, while it increases the risk of serious adverse events.

The consequence and mechanism of dietary flavonoids on androgen profiles and disorders amelioration

Androgen is a kind of steroid hormone that plays a vital role in reproductive system and homeostasis of the body. Disrupted androgen balance serves as the causal contributor to a series of physiological disorders and even diseases. Flavonoids, as an extremely frequent family of natural polyphenols, exist widely in plants and foods and have received great attention when considering their inevitable consumption and estrogen-like effects. Mounting evidence illustrates that flavonoids have a propensity to interfere with androgen synthesis and metabolism, and also have a designated improvement effect on androgen disorders. Therefore, flavonoids were divided into six subclasses based on the structural feature in this paper, and the literature about their effects on androgens published in the past ten years was summarized. It could be concluded that flavonoids have the potential to regulate androgen levels and biological effects, mainly by interfering with the hypothalamic-pituitary-gonadal axis, androgen synthesis and metabolism, androgen binding with its receptors and membrane receptors, and antioxidant effects. The faced challenges about androgen regulation by flavonoids masterly include target mechanism exploration, individual heterogeneity, food matrixes interaction, and lack of clinical study. This review also provides a scientific basis for nutritional intervention using flavonoids to improve androgen disorder symptoms.

Targeting signaling pathways in prostate cancer: mechanisms and clinical trials

Prostate cancer (PCa) affects millions of men globally. Due to advances in understanding genomic landscapes and biological functions, the treatment of PCa continues to improve. Recently, various new classes of agents, which include next-generation androgen receptor (AR) signaling inhibitors (abiraterone, enzalutamide, apalutamide, and darolutamide), bone-targeting agents (radium-223 chloride, zoledronic acid), and poly(ADP-ribose) polymerase (PARP) inhibitors (olaparib, rucaparib, and talazoparib) have been developed to treat PCa. Agents targeting other signaling pathways, including cyclin-dependent kinase (CDK)4/6, Ak strain transforming (AKT), wingless-type protein (WNT), and epigenetic marks, have successively entered clinical trials. Furthermore, prostate-specific membrane antigen (PSMA) targeting agents such as ¹⁷⁷Lu-PSMA-617 are promising theranostics that could improve both diagnostic accuracy and therapeutic efficacy. Advanced clinical studies with immune checkpoint inhibitors (ICIs) have shown limited benefits in PCa, whereas subgroups of PCa with mismatch repair (MMR) or CDK12 inactivation may benefit from ICIs treatment. In this review, we summarized the targeted agents of PCa in clinical trials and their underlying mechanisms, and further discussed their limitations and future directions.

Targeting the androgen receptor signaling pathway in advanced prostate cancer

DISCLAIMER

In an effort to expedite the publication of articles related to the COVID-19 pandemic, AJHP is posting these manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

This article summarizes current androgen receptor (AR)-directed therapies that have received regulatory approval for the treatment of advanced prostate adenocarcinoma (herein referred to as prostate cancer, PC).

SUMMARY

PC is an androgen-dependent malignancy in which ligands including testosterone and dihydrotestosterone bind to AR, initiating androgen-AR complex translocation to the nucleus followed by AR-mediated transcription of target genes. Androgen deprivation therapy (ADT), including gonadotropin hormone-releasing hormone (GnRH) agonists with or without AR antagonists (antiandrogens), GnRH antagonists, or bilateral orchiectomy, forms the backbone of treatment for patients with metastatic castration-naive PC and/or castration-resistant PC (CRPC). ADT is also an option for high-risk, early-stage PC after prostatectomy and/or radiation. While ADT is often very effective as initial therapy, resistance ultimately develops despite suppression of gonadal and/or adrenal androgens, leading to CRCPC, which is characterized by mechanisms such as reactivation of the AR signaling pathway, AR overexpression, and gene mutations in the ligand-binding domain of AR that lead to disease progression, resulting in increased symptom burden and ultimately death. However, disease in patients with CRPC is still dependent on androgen signaling, and these patients continue on ADT to maintain a castrate level of serum testosterone. Novel hormonal therapies including agents that target AR directly (eg, AR antagonists) are often added to ADT in this setting. Targeting the AR signaling pathway led to the development of second-generation AR antagonists, examples of which include enzalutamide, apalutamide, and darolutamide. These agents do not exhibit partial agonism or possess a higher affinity for AR and are not postulated to improve survival outcomes relative to their first-generation counterparts for patients with CRPC. Lastly, the emergence of ADT, including second-generation AR antagonists, has led to the development of supportive care for treatment-related adverse effects.

CONCLUSION

Major advances have been made in targeting the AR signaling pathway in patients with advanced PC. Further studies are warranted to identify the optimal sequencing of therapies to maximize treatment benefit. Mitigation of treatment-related adverse effects presents new opportunities to advance clinical pharmacy practice.

Insights into Interactions of Human Cytochrome P450 17A1: Review

Abstract:

Cytochrome P450s are a widespread and vast superfamily of hemeprotein monooxygenases that metabolize physiologically essential chemicals necessary for most species' survival, from protists to plants to humans. They catalyze the synthesis of steroid hormones, cholesterol, bile acids, and arachidonate metabolites and the degradation of endogenous compounds such as steroids, fatty acids, and other catabolizing compounds as an energy source and detoxifying xenobiotics such as drugs, procarcinogens, and carcinogens. The human CYP17A1 is one of the cytochrome P450 genes located at the 10q chromosome. The gene expression occurs in the adrenals and gonads, with minor amounts in the brain, placenta, and heart. This P450c17 cytochrome gene is a critical steroidogenesis regulator which performs two distinct activities: 17 alpha-hydroxylase activity (converting pregnenolone to 17-hydroxypregnenolone and progesterone to 17-hydroxyprogesterone, these precursors are further processed to provide glucocorticoids and sex hormones) and 17, 20-lyase activity (which converts 17-hydroxypregnenolone to DHEA). Dozens of mutations within CYP17A1 are found to cause 17-alpha-hydroxylase and 17, 20-lyase deficiency. This condition affects the function of certain hormone-producing glands, resulting in high blood pressure levels (hypertension), abnormal sexual development, and other deficiency diseases. This review highlights the changes in CYP17A1 associated with gene-gene interaction, drug-gene interaction, chemical-gene interaction, and its biochemical reactions; they have some insights to correlate with the fascinating functional characteristics of this human steroidogenic gene. The findings of our theoretical results will be helpful to further the design of specific inhibitors of CYP17A1.

Activity and safety of SHR3680, a novel antiandrogen, in patients with metastatic castration-resistant prostate cancer: a phase I/II trial

BACKGROUND

Antagonizing the androgen-receptor (AR) pathway is an effective treatment strategy for patients with metastatic castration-resistant prostate cancer (CRPC). Here, we report the results of a first-in-human phase 1/2 study which assessed the safety, pharmacokinetics, and activity of SHR3680 (a novel AR antagonist) in patients with metastatic CRPC.

METHODS

This phase 1/2 study enrolled patients with progressive metastatic CRPC who had not been previously treated with novel AR-targeted agents. In the phase 1 dose-escalation portion, patients received oral SHR3680 at a starting daily dose of 40 mg, which was subsequently escalated to 80 mg, 160 mg, 240 mg, 360 mg, and 480 mg per day. In phase 2 dose-expansion portion, patients were randomized to receive daily dose of 80 mg, 160 mg, or 240 mg of SHR3680. The primary endpoint in phase 1 was safety and tolerability and in phase 2 was the proportion of patients with a prostate-specific antigen (PSA) response (≥ 50% decrease of PSA level) at week 12.

RESULTS

A total of 197 eligible patients were enrolled and received SHR3680 treatment, including 18 patients in phase 1 and 179 patients in phase 2. No dose-limiting toxicities were reported and the maximum tolerated dose was not reached. Treatment-related adverse events (TRAEs) occurred in 116 (58.9%) patients, with the most common one being proteinuria (13.7%). TRAEs of grade ≥ 3 occurred in only 23 (11.7%) patients, and no treatment-related deaths occurred. Antitumor activities were evident at all doses, including PSA response at week 12 in 134 (68.0%; 95% CI, 61.0-74.5) patients, stabilized bone disease at week 12 in 174 (88.3%; 95% CI, 87.2-95.5) patients, and responses in soft tissue lesions in 21 (34.4%, 95% CI, 22.7-47.7) of 61 patients.

CONCLUSION

SHR3680 was well tolerated and safe, with promising anti-tumor activity across all doses tested in patients with metastatic CRPC. The dose of 240 mg daily was recommended for further phase 3 study.

TRIAL REGISTRATION

Clinical trials.gov NCT02691975; registered February 25, 2016.

Circular RNAs in prostate cancer: Biogenesis,biological functions, and clinical significance

Circular RNAs (circRNAs) are covalently closed RNA molecules that play important regulatory roles in various tumors. Prostate cancer (PCa) is one of the most common malignant tumors in the world, with high morbidity and mortality. In recent years, more and more circRNAs have been found to be abnormally expressed and involved in the occurrence and development of PCa, including cell proliferation, apoptosis, invasion, migration, metastasis, chemotherapy resistance, and radiotherapy resistance. Most of the circRNAs regulate biological behaviors of cancer through a competitive endogenous RNA (ceRNA) regulatory mechanism, and some can exert their functions by binding to proteins. circRNAs are also associated with many clinicopathological features of PCa, including tumor grade, lymph node metastasis, and distant metastasis. In addition, circRNAs are potential diagnostic and prognostic biomarkers for PCa. Considering their critical regulatory roles in the progression of PCa, circRNAs would be the potential therapeutic targets. In this paper, the current research status of circRNAs in PCa is briefly reviewed.

New Insight into Molecular and Hormonal Connection in Andrology

Hormones and cytokines are known to regulate cellular functions in the testes. These biomolecules induce a broad spectrum of effects on various level of spermatogenesis, and among them is the modulation of cell junction restructuring between Sertoli cells and germ cells in the seminiferous epithelium. Cytokines and androgens are closely related, and both correct testicular development and the maintenance of spermatogenesis depend on their function. Cytokines also play a crucial role in the immune testicular system, activating and directing leucocytes across the endothelial barrier to the inflammatory site, as well as in increasing their adhesion to the vascular wall. The purpose of this review is to revise the most recent findings on molecular mechanisms that play a key role in male sexual function, focusing on three specific molecular patterns, namely, cytokines, miRNAs, and endothelial progenitor cells. Numerous reports on the interactions between the immune and endocrine systems can be found in the literature. However, there is not yet a multi-approach review of the literature underlying the role between molecular patterns and testicular and sexual function.

Prostate cancer

Prostate cancer is a complex disease that affects millions of men globally, predominantly in high human development index regions. Patients with localized disease at a low to intermediate risk of recurrence generally have a favourable outcome of 99% overall survival for 10 years if the disease is detected and treated at an early stage. Key genetic alterations include fusions of TMPRSS2 with ETS family genes, amplification of the MYC oncogene, deletion and/or mutation of PTEN and TP53 and, in advanced disease, amplification and/or mutation of the androgen receptor (AR). Prostate cancer is usually diagnosed by prostate biopsy prompted by a blood test to measure prostate-specific antigen levels and/or digital rectal examination. Treatment for localized disease includes active surveillance, radical prostatectomy or ablative radiotherapy as curative approaches. Men whose disease relapses after prostatectomy are treated with salvage radiotherapy and/or androgen deprivation therapy (ADT) for local relapse, or with ADT combined with chemotherapy or novel androgen signalling-targeted agents for systemic relapse. Advanced prostate cancer often progresses despite androgen ablation and is then considered castration-resistant and incurable. Current treatment options include AR-targeted agents, chemotherapy, radionuclides and the poly(ADP-ribose) inhibitor olaparib. Current research aims to improve prostate cancer detection, management and outcomes, including understanding the fundamental biology at all stages of the disease.

Prostate cancer

Prostate cancer is a complex disease that affects millions of men globally, predominantly in high human development index regions. Patients with localized disease at a low to intermediate risk of recurrence generally have a favourable outcome of 99% overall survival for 10 years if the disease is detected and treated at an early stage. Key genetic alterations include fusions of TMPRSS2 with ETS family genes, amplification of the MYC oncogene, deletion and/or mutation of PTEN and TP53 and, in advanced disease, amplification and/or mutation of the androgen receptor (AR). Prostate cancer is usually diagnosed by prostate biopsy prompted by a blood test to measure prostate-specific antigen levels and/or digital rectal examination. Treatment for localized disease includes active surveillance, radical prostatectomy or ablative radiotherapy as curative approaches. Men whose disease relapses after prostatectomy are treated with salvage radiotherapy and/or androgen deprivation therapy (ADT) for local relapse, or with ADT combined with chemotherapy or novel androgen signalling-targeted agents for systemic relapse. Advanced prostate cancer often progresses despite androgen ablation and is then considered castration-resistant and incurable. Current treatment options include AR-targeted agents, chemotherapy, radionuclides and the poly(ADP-ribose) inhibitor olaparib. Current research aims to improve prostate cancer detection, management and outcomes, including understanding the fundamental biology at all stages of the disease.

Next-generation androgen receptor inhibitors in non-metastatic castration-resistant prostate cancer

Until recently, continuing androgen deprivation therapy (ADT) and closely monitoring patients until evolution towards metastatic castration-resistant prostate cancer (CRPC) were recommended in men with non-metastatic CRPC (nmCRPC). Because delaying the development of metastases and symptoms in these patients is a major issue, several trials have investigated next-generation androgen receptor (AR) axis inhibitors such as apalutamide, darolutamide, and enzalutamide in this setting. This review summarizes the recent advances in the management of nmCRPC, highlighting the favourable impact of next-generation AR inhibitors on metastases-free survival, overall survival and other clinically meaningful endpoints.

Mechanisms of Taxane Resistance

The taxane family of chemotherapy drugs has been used to treat a variety of mostly epithelial-derived tumors and remain the first-line treatment for some cancers. Despite the improved survival time and reduction of tumor size observed in some patients, many have no response to the drugs or develop resistance over time. Taxane resistance is multi-faceted and involves multiple pathways in proliferation, apoptosis, metabolism, and the transport of foreign substances. In this review, we dive deeper into hypothesized resistance mechanisms from research during the last decade, with a focus on the cancer types that use taxanes as first-line treatment but frequently develop resistance to them. Furthermore, we will discuss current clinical inhibitors and those yet to be approved that target key pathways or proteins and aim to reverse resistance in combination with taxanes or individually. Lastly, we will highlight taxane response biomarkers, specific genes with monitored expression and correlated with response to taxanes, mentioning those currently being used and those that should be adopted. The future directions of taxanes involve more personalized approaches to treatment by tailoring drug-inhibitor combinations or alternatives depending on levels of resistance biomarkers. We hope that this review will identify gaps in knowledge surrounding taxane resistance that future research or clinical trials can overcome.

Pharmacological inhibition of androgen receptor expression induces cell death in prostate cancer cells

The androgen receptor (AR) plays an important role in the pathogenesis and development of prostate cancer (PCa). Mostly, PCa progresses to androgen-independent PCa, which has activated AR signaling from androgen-dependent PCa. Thus, inhibition of AR signaling may be an important therapeutic target in androgen-dependent and castration-resistant PCa. In this study, we determined the anticancer effect of a newly found natural compound, sakurasosaponin (S-saponin), using androgen-dependent and castration-resistant PCa cell lines. S-saponin induces mitochondrial-mediated cell death in both androgen-dependent (LNCaP) and castration-resistant (22Rv1 and C4-2) PCa cells, via AR expression. S-saponin treatment induces a decrease in AR expression in a time- and dose-dependent manner and a potent decrease in the expression of its target genes, including prostate-specific antigen (PSA), transmembrane protease, serin 2 (TMPRSS2), and NK3 homeobox 1 (NKX3.1). Furthermore, S-saponin treatment decreases B-cell lymphoma-extra large (Bcl-xL) and mitochondrial membrane potential, thereby increasing the release of cytochrome c into the cytosol. Moreover, Bcl-xL inhibition and subsequent mitochondria-mediated cell death caused by S-saponin were reversed by Bcl-xL or AR overexpression. Interestingly, S-saponin-mediated cell death was significantly reduced by a reactive oxygen species (ROS) scavenger, N-acetylcystein. Animal xenograft experiments showed that S-saponin treatment significantly reduced tumor growth of AR-positive 22Rv1 xenografts but not AR-negative PC-3 xenografts. Taken together, for the first time, our results revealed that S-saponin induces mitochondrial-mediated cell death in androgen-dependent and castration-resistant cells through regulation of AR mechanisms, including downregulation of Bcl-xL expression and induction of ROS stress by decreasing mitochondrial membrane potential.

Roles of Reactive Oxygen Species in Biological Behaviors of Prostate Cancer

Prostate cancer (PCa), known as a heterogenous disease, has a high incidence and mortality rate around the world and seriously threatens public health. As an inevitable by-product of cellular metabolism, reactive oxygen species (ROS) exhibit beneficial effects by regulating signaling cascades and homeostasis. More and more evidence highlights that PCa is closely associated with age, and high levels of ROS are driven through activation of several signaling pathways with age, which facilitate the initiation, development, and progression of PCa. Nevertheless, excessive amounts of ROS result in harmful effects, such as genotoxicity and cell death. On the other hand, PCa cells adaptively upregulate antioxidant genes to detoxify from ROS, suggesting that a subtle balance of intracellular ROS levels is required for cancer cell functions. The current review discusses the generation and biological roles of ROS in PCa and provides new strategies based on the regulation of ROS for the treatment of PCa.

A Mansonone Derivative Coupled with Monoclonal Antibody 4D5-Modified Chitosan Inhibit AKR1C3 to Treat Castration-Resistant Prostate Cancer

Purpose

Aldo-ketoreductase (AKR) 1C3 is crucial for testosterone synthesis. Abnormally high expression/activity of AKR1C3 can promote castration-resistant prostate cancer (CRPC). A mansonone derivative and AKR1C3 inhibitor, 6e, was combined with 4D5 (extracellular fragment of the monoclonal antibody of human epidermal growth factor receptor-2)-modified chitosan to achieve a nanodrug-delivery system (CS-4D5/6e) to treat CRPC.

Materials and Methods

Morphologies/properties of CS-4D5/6e were characterized by atomic force microscopy, zeta-potential analysis, and Fourier transform-infrared spectroscopy. CS-4D5/6e uptake was measured by immunofluorescence under confocal laser scanning microscopy. Testosterone in LNCaP cells overexpressing human AKR1C3 (LNCaP-AKR1C3) and cell lysates was measured to reflect AKR1C3 activity. Androgen receptor (AR) and prostate-specific antigen (PSA) expression was measured by Western blotting. CS-4D5/6e-based inhibition of AKR1C3 was evaluated in tumor-xenografted mice.

Results

CS-4D5/6e was oblate, with a particle size of 200-300 nm and thickness of 1-5 nm. Zeta potential was 1.39±0.248 mV. 6e content in CS-4D5/6e was 7.3±1.4% and was 18±3.6% for 4D5. 6e and CS-4D5/6e inhibited testosterone production significantly in a concentration-dependent manner in LNCaP-AKR1C3 cells, and a decrease in expression of AKR1C3, PSA, and AR was noted. Half-maximal inhibitory concentration of CS-4D5/6e on LNCaP-AKR1C3 cells was significantly lower than that in LNCaP cells (P<0.05). CS-4D5/6e significantly reduced growth of 22Rv1 tumor xenografts by 57.00% compared with that in the vehicle group (P<0.01).

Conclusion

We demonstrated the antineoplastic activity of a potent AKR1C3 inhibitor (6e) and its nanodrug-delivery system (CS-4D5/6e). First, CS-4D5/6e targeted HER2-positive CRPC cells. Second, it transferred 6e (an AKR1C3 inhibitor) to achieve a reduction in intratumoral testosterone production. Compared with 6e, CS-4D5/6e showed lower systemic toxicity. CS-4D5/6e inhibited tumor growth effectively in mice implanted with tumor xenografts by downregulating testosterone production mediated by intratumoral AKR1C3. These results showed a promising strategy for treatment of the CRPC that develops invariably in prostate-cancer patients.

Expanding armamentarium in advanced prostate cancer management: are all novel antiandrogens the same?

Prostate cancer (PCa) is the most common cancer in men. Androgen receptor axis plays a crucial role in the carcinogenesis of PCa. The mainstay treatment of prostate cancer is blockage of androgen receptor axis but in a vast majority of patient resistance to androgen deprivation therapy is inevitable. After using enzalutamide, the first new generation anti-androgen (AA), two new generation AA drugs were synthesized. New generation anti-androgen drugs are used especially in castration resistance prostate cancer. But recently, there are new publications regarding using new generation anti-androgens in castration sensitive prostate cancer patients. In this review, we will compare structure, mechanisms of effect and clinical outcomes in phase 3 trials of these new generation AA drugs.

Multifaceted Function of MicroRNA-299-3p Fosters an Antitumor Environment Through Modulation of Androgen Receptor and VEGFA Signaling Pathways in Prostate Cancer

Prostate cancer (PCa) is one of the most common cancers to affect men worldwide. Androgen receptor (AR) signaling is central to PCa and PCa therapy. MicroRNAs (miRNAs) play crucial roles in the regulation of prostate cancer through modulation of signaling pathways. In the present study, we illustrate the functional significance and therapeutic benefit of miR-299-3p, an AR targeting microRNA, in PCa progression. We noted loss of expression of miR-299-3p in prostate tumors compared to noncancerous prostate tissues. Replenishment of miR-299-3p in C4-2B, 22Rv-1 and PC-3 cells contributed to cell cycle arrest, reduced proliferation, migration and increased expression of apoptotic markers. Additionally, overexpression of miR-299-3p induced a reduction of AR, PSA and VEGFA expression. AGO-RNA pulldown experiment showed enrichment of AR, VEGFA and miR-299-3p in C4-2B cells overexpressing miR-299-3p. miR-299-3p overexpression also inhibited epithelial mesenchymal transition, expression of Slug, TGF-β3, phospho-AKT and phospho-PRAS40, but increased expression of E-cadherin. Furthermore, miR-299 overexpression resulted in reduced tumor growth in xenograft models and increased drug sensitivity. Overall, this study has identified novel mechanisms of antitumor and antimigration function of miR-299-3p through modulation of AR and VEGFA signaling pathways which lead to improved drug sensitivity of PCa.

NONO and tumorigenesis: More than splicing

The non-POU domain-containing octamer-binding protein NONO/p54^nrb , which belongs to the Drosophila behaviour/human splicing (DBHS) family, is a multifunctional nuclear protein rarely functioning alone. Emerging solid evidences showed that NONO engages in almost every step of gene regulation, including but not limited to mRNA splicing, DNA unwinding, transcriptional regulation, nuclear retention of defective RNA and DNA repair. NONO is involved in many biological processes including cell proliferation, apoptosis, migration and DNA damage repair. Dysregulation of NONO has been found in many types of cancer. In this review, we summarize the current and fast-growing knowledge about the regulation of NONO, its biological function and implications in tumorigenesis and cancer progression. Overall, significant findings about the roles of NONO have been made, which might make NONO to be a new biomarker or/and a possible therapeutic target for cancers.

Liver tests increase on abiraterone acetate in men with metastatic prostate cancer: Natural history, management and outcome

BACKGROUND

Abiraterone acetate (abiraterone) combined with prednisone is a standard of care in metastatic castration-resistant prostate cancer. Recently, benefit in overall survival was reported in metastatic castration-sensitive prostate cancer also, and an extension of indication has been granted. Abiraterone is seldom associated with liver toxicity. The clinical management and the outcome of patients with transaminase increase while on abiraterone have not been described.

PATIENTS AND METHOD

We identified 25 men with metastatic prostate cancer and liver function test disorders occurring while on abiraterone treatment from December 2009 to September 2017 in three oncology centres in France.

RESULTS

Forty-six liver disorder events occurred in 25 patients while on abiraterone treatment. The median age at liver function test increase was 67 (55-85) years. The incidence of aspartate aminotransférase (AST) (24 events) and that of alanine aminotransférase (ALT) (22 events) increases were similar. Liver toxicity was of grade 1, 2 and 3 (Common Terminology Criteria for Adverse Events. version 4) in 7 (32%), 6 (27%) and 9 (41%) patients for ALT, and in 12 (50%), 6 (25%) and 6 (25%) for AST, respectively. The median time from abiraterone initiation to the detection of liver toxicity was 7.1 (4-95) weeks. The median time from highest ALT/AST increase to normalisation was 6.2 [2-14] weeks. In 13 patients (52%), liver tests spontaneously returned to baseline values, while abiraterone was continued at full dose.

CONCLUSION

Liver function test increase is a rare event that typically occurs within the first two months on abiraterone. Most patients experience normalisation of the tests, either spontaneously or after dose reduction/discontinuation.

The ternary complex factor protein ELK1 is an independent prognosticator of disease recurrence in prostate cancer

BACKGROUND

Both hormone-sensitive and castration- and enzalutamide-resistant prostate cancers (PCa) depend on the ternary complex factor (TCF) protein ELK1 to serve as a tethering protein for the androgen receptor (AR) to activate a critical set of growth genes. The two sites in ELK1 required for AR binding are conserved in other members of the TCF subfamily, ELK3 and ELK4. Here we examine the potential utility of the three proteins as prognosticators of disease recurrence in PCa.

METHODS

Transcriptional activity assays; Retrospective analysis of PCa recurrence using data on 501 patients in The Cancer Genome Atlas (TCGA) database; Unpaired Wilcoxon rank-sum test and multiple comparison correction using the Holm's method; Spearman's correlations; Kaplan-Meier methods; Univariable and multivariable Cox regression analyses; LASSO-based penalized Cox regression models; Time-dependent area under the receiver operating characteristic (ROC) curve.

RESULTS

ELK4 but not ELK3 was coactivated by AR similar to ELK1. Tumor expression of neither ELK3 nor ELK4 was associated with disease-free survival (DFS). ELK1 was associated with higher clinical T-stage, pathology T-stage, Gleason score, prognostic grade, and positive lymph node status. ELK1 was a negative prognosticator of DFS, independent of ELK3, ELK4, clinical T-stage, pathology T-stage, prognostic grade, lymph node status, age, and race. Inclusion of ELK1 increased the abilities of the Oncotype DX and Prolaris gene panels to predict disease recurrence, correctly predicting disease recurrence in a unique subset of patients.

CONCLUSIONS

ELK1 is a strong, independent prognosticator of disease recurrence in PCa, underscoring its unique role in PCa growth. Inclusion of ELK1 may enhance the utility of currently used prognosticators for clinical decision making in prostate cancer.

Interaction energies between two antiandrogenic and one androgenic agonist receptor in the presence of a T877A mutation in prostate cancer: a quantum chemistry analysis

We provide a detailed picture of the interactions between the androgen receptor T877A mutation and three different compounds used in the treatment of prostate cancer.

Role of MicroRNAs in Treatment Response in Prostate Cancer

Prostate cancer (PCa) is the most common non-skin cancer in men worldwide, resulting in significant mortality and morbidity. Depending on the grade and stage of the cancer, patients may be given radiation therapy, hormonal therapy, or chemotherapy. However, more than half of these patients develop resistance to treatment, leading to disease progression and metastases, often with lethal consequences. MicroRNAs (miRNAs) are short, non-coding RNAs, which regulate numerous physiological as well as pathological processes, including cancer. miRNAs mediate their regulatory effect predominately by binding to the 3'-untranslated region (UTR) of their target mRNAs. In this review, we will describe the mechanisms by which miRNAs mediate resistance to radiation and drug therapy (i.e. hormone therapy and chemotherapy) in PCa, including control of apoptosis, cell growth and proliferation, autophagy, epithelial-to-mesenchymal transition (EMT), invasion and metastasis, and cancer stem cells (CSCs). Furthermore, we will discuss the utility of circulating miRNAs isolated from different body fluids of prostate cancer patients as non-invasive biomarkers of cancer detection, disease progression, and therapy response. Finally, we will shortlist the candidate miRNAs, which may have a role in drug and radioresistance, that could potentially be used as predictive biomarkers of treatment response.

Screening of Drug Repositioning Candidates for Castration Resistant Prostate Cancer

Purpose: Most prostate cancers (PCs) initially respond to androgen deprivation therapy (ADT), but eventually many PC patients develop castration resistant PC (CRPC). Currently, available drugs that have been approved for the treatment of CRPC patients are limited. Computational drug repositioning methods using public databases represent a promising and efficient tool for discovering new uses for existing drugs. The purpose of the present study is to predict drug candidates that can treat CRPC using a computational method that integrates publicly available gene expression data of tumors from CRPC patients, drug-induced gene expression data and drug response activity data. Methods: Gene expression data from tumoral and normal or benign prostate tissue samples in CRPC patients were downloaded from the Gene Expression Omnibus (GEO) and differentially expressed genes (DEGs) in CRPC were determined with a meta-signature analysis by a metaDE R package. Additionally, drug activity data were downloaded from the ChEMBL database. Furthermore, the drug-induced gene expression data were downloaded from the LINCS database. The reversal relationship between the CRPC and drug gene expression signatures as the Reverse Gene Expression Scores (RGES) were computed. Drug candidates to treat CRPC were predicted using summarized scores (sRGES). Additionally, synergic effects of drug combinations were predicted with a Target Inhibition interaction using the Minimization and Maximization Averaging (TIMMA) algorithm. Results: The drug candidates of sorafenib, olaparib, elesclomol, tanespimycin, and ponatinib were predicted to be active for the treatment of CRPC. Meanwhile, CRPC-related genes, in this case MYL9, E2F2, APOE, and ZFP36, were identified as having gene expression data that can be reversed by these drugs. Additionally, lenalidomide in combination with pazopanib was predicted to be most potent for CRPC. Conclusion: These findings support the use of a computational reversal gene expression approach to identify new drug and drug combination candidates that can be used to treat CRPC.

MicroRNA-205 is associated with diabetes mellitus-induced erectile dysfunction via down-regulating the androgen receptor

As a major class of regulatory genes in majority metazoans, microRNAs (miRs) play an important role in various diseases including diabetes mellitus (DM). Lack of androgens has previously been associated with DM-induced erectile dysfunction (DMED). In addition, the biological functioning of androgen is mediated by androgen receptor (AR). Herein, we sought to investigate whether miRs participate in AR-associated DMED. Sprague-Dawlay rats were employed to establish DMED models. After modelling, levels of miR-205 and AR in their cavernous bodies were measured. The relationship between miR-205 and AR was verified using a dual-luciferase reporter gene assay. The underlying regulatory mechanisms of miR-205 were investigated in concert with the treatment of mimics or inhibitors of miR-205, or AR overexpression in the cavernous smooth muscle cells (CSMCs) isolated from rats with DMED. Meanwhile, the effects of miR-205 and AR on cell proliferation and apoptosis were evaluated using MTT assay and flow cytometry respectively. Rats with DMED presented with increased miR-205 and decreased AR levels in the cavernous bodies. AR was identified as a target gene of miR-205. Down-regulation of miR-205 or up-regulation of AR could increase proliferation and inhibits apoptosis of CSMCs in addition to improvements in the erectile functioning of rats with DMED. In summary, miR-205 may contribute to the pathogenesis of DMED via down-regulation of AR expressions.

Enzalutamide, an oral androgen receptor inhibitor for treatment of castration-resistant prostate cancer

Androgen receptor (AR) signaling is a key pathway in prostate cancer, and patients are initially treated with androgen deprivation therapy. Patients who have stopped responding to androgen deprivation therapy are considered to have castration-resistant prostate cancer (CRPC), which is still dependent on AR signaling. Enzalutamide, an orally available AR inhibitor, was initially approved by the US FDA for the treatment of patients with metastatic CRPC who have previously received docetaxel. The indication was subsequently extended to include all patients with metastatic CRPC, and most recently to include patients with nonmetastatic CRPC. This review summarizes the body of evidence supporting enzalutamide efficacy and safety in CRPC.

Strategy for Tumor-Selective Disruption of Androgen Receptor Function in the Spectrum of Prostate Cancer

PURPOSE

Testosterone suppression in prostate cancer is limited by serious side effects and resistance via restoration of androgen receptor (AR) functionality. ELK1 is required for AR-dependent growth in various hormone-dependent and castration-resistant prostate cancer models. The amino-terminal domain of AR docks at two sites on ELK1 to coactivate essential growth genes. This study explores the ability of small molecules to disrupt the ELK1-AR interaction in the spectrum of prostate cancer, inhibiting AR activity in a manner that would predict functional tumor selectivity.

EXPERIMENTAL DESIGN

Small-molecule drug discovery and extensive biological characterization of a lead compound.

RESULTS

We have discovered a lead molecule (KCI807) that selectively disrupts ELK1-dependent promoter activation by wild-type and variant ARs without interfering with ELK1 activation by ERK. KCI807 has an obligatory flavone scaffold and functional hydroxyl groups on C5 and C3'. KCI807 binds to AR, blocking ELK1 binding, and selectively blocks recruitment of AR to chromatin by ELK1. KCI807 primarily affects a subset of AR target growth genes selectively suppressing AR-dependent growth of prostate cancer cell lines with a better inhibitory profile than enzalutamide. KCI807 also inhibits in vivo growth of castration/enzalutamide-resistant cell line-derived and patient-derived tumor xenografts. In the rodent model, KCI807 has a plasma half-life of 6 hours, and maintenance of its antitumor effect is limited by self-induced metabolism at its 3'-hydroxyl.

CONCLUSIONS

The results offer a mechanism-based therapeutic paradigm for disrupting the AR growth-promoting axis in the spectrum of prostate tumors while reducing global suppression of testosterone actions. KCI807 offers a good lead molecule for drug development.

Quantification of bone flare on 18F-NaF PET/CT in metastatic castration-resistant prostate cancer

BACKGROUND

Bone flare has been observed on ^99mTc-MDP bone scans of patients with metastatic castration-resistant prostate cancer (mCRPC). This exploratory study investigates bone flare in mCRPC patients receiving androgen receptor (AR) inhibitors using ¹⁸F-NaF PET/CT.

METHODS

Twenty-nine mCRPC patients undergoing AR-inhibiting therapy (abiraterone, orteronel, enzalutamide) received NaF PET/CT scans at baseline, week 6, and week 12 of treatment. SUV metrics were extracted globally for each patient (SUV) and for each individual lesion (iSUV). Bone flare was defined as increasing SUV metrics or lesion number at week 6 followed by subsequent week 12 decrease. Differences in metrics across timepoints were compared using Wilcoxon tests. Cox proportional hazard regression was conducted between global metrics and progression-free survival (PFS).

RESULTS

Total SUV was most sensitive for flare detection and was identified in 14/23 (61%) patients receiving CYP17A1-inhibitors (abiraterone, orteronel), and not identified in any of six patients receiving enzalutamide. The appearance of new lesions did not account for initial increases in SUV metrics. iSUV metrics followed patient-level trends: bone flare positive patients showed a median of 72% (range: 0-100%) of lesions with total iSUV flare. Increasing mean SUV at week 6 correlated with extended PFS (HR = 0.58, p = 0.02).

CONCLUSION

NaF PET bone flare was present on 61% of mCRPC patients in the first 6 weeks of treatment with CYP17A1-inhibitors. Characterization provided in this study suggests favorable PFS in patients showing bone flare. This characterization of NaF flare is important for guiding treatment assessment schedules to better distinguish between patients showing bone flare and those truly progressing, and should be performed for all emerging mCRPC treatments and imaging agents.

Bone health during endocrine therapy for cancer

Preservation of bone health remains a long-term clinical challenge in patients with breast and prostate cancer. Osteoporosis, defined by a loss of bone mass and microarchitecture, often results in fragility fractures that are typically associated with a high socioeconomic burden. Endocrine therapy, a mainstay treatment in the management of patients with hormone-sensitive breast and prostate cancer in the adjuvant setting, commonly exerts adverse effects on the musculoskeletal system and is associated with an increased risk of osteoporosis and fractures. Adjuvant use of gonadotropin-releasing hormone analogues, which can also be used in metastatic disease, in combination with tamoxifen in premenopausal women, and aromatase inhibitors in postmenopausal women with hormone-sensitive breast cancer, causes rapid bone loss and fragility fractures. By contrast, selective oestrogen receptor modulators, such as tamoxifen, have bone-protective effects in postmenopausal women. In men with castration-sensitive prostate cancer, androgen deprivation is achieved with drugs that lower gonadotropin levels, and these drugs can be combined with androgen receptor antagonists. These therapies induce a high bone turnover with rapid bone loss that is reminiscent of the changes occurring in early menopause and result in an increased risk of fracture. In this Review, we describe how adjuvant endocrine therapies of breast and prostate cancer impair bone health and outline evidence from randomised controlled trials of strategies to reduce risk of fracture.

Enzalutamide therapy for advanced prostate cancer: efficacy, resistance and beyond

The androgen receptor drives the growth of metastatic castration-resistant prostate cancer. This has led to the development of multiple novel drugs targeting this hormone-regulated transcription factor, such as enzalutamide – a potent androgen receptor antagonist. Despite the plethora of possible treatment options, the absolute survival benefit of each treatment separately is limited to a few months. Therefore, current research efforts are directed to determine the optimal sequence of therapies, discover novel drugs effective in metastatic castration-resistant prostate cancer and define patient subpopulations that ultimately benefit from these treatments. Molecular studies provide evidence on which pathways mediate treatment resistance and may lead to improved treatment for metastatic castration-resistant prostate cancer. This review provides, firstly a concise overview of the clinical development, use and effectiveness of enzalutamide in the treatment of advanced prostate cancer, secondly it describes translational research addressing enzalutamide response vs resistance and lastly highlights novel potential treatment strategies in the enzalutamide-resistant setting.

Abiraterone in metastatic castration-resistant prostate cancer: Efficacy and safety in unselected patients

BACKGROUND

Abiraterone acetate (AA), an androgen biosynthesis inhibitor, is now a standard of care for men with metastatic, castration-sensitive and castration-resistant prostate cancer (mCRPC). Data exploring real-world toxicity and outcomes are scarce.

METHODS

Retrospective study on unselected patients with mCRPC on AA plus steroids.

RESULTS

93 patients were included in the study. Median duration of treatment by AA was 7.5 months (95% CI 5.7-12) among the 58 patients pretreated with chemotherapy, versus 12.7 months ( 95% CI 8.2-35.9) among the 33 chemo-naive patients. Median survivals would reach 13.4 months (95% CI 10.2-19.1) and 36.4 months (95% CI 24.7-41.5) respectively. Rates of hypokalemia, peripheral edema, hypertension, cardiac failure, and overall survival assessments in patients with and without prior chemotherapy were similar to that previously reported in phase 3 randomized trials. The median survival time without adverse event of special interest was 7.5 months for hypokalemia and hypertension, and 5.3 months for liver-function test abnormalities (it was not reached for cardiac disorders).

CONCLUSION

Our findings provide further evidence for the survival benefits of AA with a low frequency of additional adverse events among unselected patients. In patients who have not developed hypokalemia or a transaminase increase within 7.5 and 5.3 months respectively, a lighter systematic monitoring may be considered.

Clinical Development of Darolutamide: A Novel Androgen Receptor Antagonist for the Treatment of Prostate Cancer

Prostate cancer (PC) is the second most common cancer in men and is the fifth leading cause of cancer-related deaths among men. Androgen receptor (AR) signaling plays a key role in PC tumor growth and progression, with androgens stimulating PC proliferation and survival. Castration-resistant PC (CRPC) is characterized by increasing levels of prostate-specific antigen or radiographic progression despite androgen-deprivation therapy (ADT). In most patients, castration resistance results from aberrations in AR or the AR signaling pathway. Up to one-third of patients with localized high-risk PC will have disease progression on local therapy and develop CRPC. This review summarizes the key clinical data, including ongoing trials, for hormonal therapies in CRPC and provides an overview of the clinical development of darolutamide, a novel, nonsteroidal AR antagonist currently in phase III development for the treatment of nonmetastatic CRPC and metastatic hormone-sensitive PC. In phase I/II trials, darolutamide has demonstrated a favorable safety profile, antitumor activity, and significant decreases in prostate-specific antigen in patients with metastatic CRPC. In the phase III ARAMIS (NCT02200614; A Multinational, Randomized, Double-Blind, Placebo-Controlled, Phase III Efficacy and Safety Study of Darolutamide [ODM-201] in Men With High-Risk Non-metastatic Castration-Resistant Prostate Cancer) study, metastasis-free survival is being evaluated in men with nonmetastatic CRPC who will receive ADT in combination with darolutamide or placebo. The ARASENS (NCT02799602; A Randomized, Double-Blind, Placebo Controlled Phase III Study of Darolutamide [ODM-201] Versus Placebo in Addition to Standard Androgen Deprivation Therapy and Docetaxel in Patients With Metastatic Hormone Sensitive Prostate Cancer) study is a placebo-controlled trial assessing whether the addition of darolutamide to ADT and docetaxel significantly prolongs overall survival in men with metastatic hormone-sensitive PC.

Androgen receptor (AR) degradation enhancer ASC-J9® in an FDA-approved formulated solution suppresses castration resistant prostate cancer cell growth

ASC-J9^® is a recently-developed androgen receptor (AR)-degradation enhancer that effectively suppresses castration resistant prostate cancer (PCa) cell proliferation and invasion. The optimal half maximum inhibitory concentrations (IC₅₀) of ASC-J9^® at various PCa cell confluences (20%, 50%, and 100%) were assessed via both short-term MTT growth assays and long-term clonogenic proliferation assays. Our results indicate that the IC₅₀ values for ASC-J9^® increased with increasing cell confluency. The IC₅₀ values were significantly decreased in PCa AR-positive cells compared to PCa AR-negative cells or in normal prostate cells. This suggests that ASC-J9^® may function mainly via targeting the AR-positive PCa cells with limited unwanted side-effects to suppress the surrounding normal prostate cells. Mechanism dissection indicated that ASC-J9^® might function via altering the apoptosis signals to suppress the PCa AR-negative PC-3 cells. Preclinical studies using multiple in vitro PCa cell lines and an in vivo mouse model with xenografted castration-resistant PCa CWR22Rv1 cells demonstrated that ASC-J9^® has similar AR degradation effects when dissolved in FDA-approved solvents, including DMSO, PEG-400:Tween-80 (95:5), DMA:Labrasol:Tween-80 (10:45:45), and DMA:Labrasol:Tween-20 (10:45:45). Together, results from preclinical studies suggest a potential new therapy with AR-degradation enhancer ASC-J9^® may potentially be ready to be used in human clinical trials in order to better suppress PCa at later castration resistant stages.

Combination treatment with docetaxel and histone deacetylase inhibitors downregulates androgen receptor signaling in castration-resistant prostate cancer

Backgrounds Since most patients with castration-resistant prostate cancer (CRPC) develop resistance to its standard therapy docetaxel, many studies have attempted to identify novel combination treatment to meet the large clinical unmet need. In this study, we examined whether histone deacetylase inhibitors (HDACIs) enhanced the effect of docetaxel on AR signaling in CRPC cells harboring AR and its splice variants. Methods HDACIs (vorinostat and CG200745) were tested for their ability to enhance the effects of docetaxel on cell viability and inhibition of AR signaling in CRPC 22Rv1 and VCaP cells by using CellTiter-Glo™ Luminescent cell viability assay, synergy index analysis and Western blotting. The nuclear localization of AR was examined via immunocytochemical staining in 22Rv1 cells and primary tumor cells from a patient with CRPC. Results Combination treatment with HDACIs (vorinostat or CG200745) and docetaxel synergistically inhibited the growth of 22Rv1 and VCaP cells. Consistently, the combination treatment decreased the levels of full-length AR (AR-FL), AR splice variants (AR-Vs), prostate-specific antigen (PSA), and anti-apoptotic Bcl-2 proteins more efficiently compared with docetaxel or vorinostat alone. Moreover, the combination treatment accelerated the acetylation and bundling of tubulin, which significantly inhibited the nuclear accumulation of AR in 22Rv1 cells. The cytoplasmic colocalization of AR-FL and AR-V7 with microtubule bundles increased after combination treatment in primary tumor cells from a patient with CRPC. Conclusions The results suggested that docetaxel, in combination with HDACIs, suppressed the expression and nuclear translocation of AR-FL and AR-Vs and showed synergistic anti-proliferative effect in CRPC cells. This combination therapy may be useful for the treatment of patients with CRPC.

The evolution of chemotherapy for the treatment of prostate cancer

Chemotherapy has been explored as a treatment option for metastatic prostate cancer since the early 1980s. Docetaxel, a taxane chemotherapeutic, was approved for the treatment of men with metastatic castration-resistant prostate cancer in 2004, and is now standard of care for late stage disease. Recent clinical studies demonstrated that patients with metastatic castration-sensitive disease, and possibly those with high-risk localized prostate cancer also benefit from docetaxel administration, expanding the role of chemotherapy in the prostate cancer treatment landscape. Another taxane, cabazitaxel, is approved for post-docetaxel metastatic castration-resistant prostate cancer. Taxanes and other chemotherapeutics, such as carboplatin, are now being tested in combination regimens. This review presents an outline of recent and ongoing clinical studies assessing docetaxel and its derivative cabazitaxel at different stages of the disease, and in various combinations with other agents. We summarize current knowledge on biomarkers predictive of response to chemotherapy, which may in future be used to guide individualized treatment decisions.

Effect of food on abiraterone pharmacokinetics: a review

Recent reports suggest a potentially beneficial increase in abiraterone exposure when abiraterone acetate plus prednisone is administered with food. We evaluated the basis for current dosing recommendations under modified fasted conditions for patients with metastatic castration-resistant prostate cancer with a PubMed search of studies assessing the impact of food on abiraterone pharmacokinetics. Studies show that abiraterone exposure increases with administration in a fed versus fasted state and with high-fat versus low-fat meals. Food effect is substantially attenuated in metastatic castration-resistant prostate cancer patients compared with healthy subjects. The potential variability in absorption, unproven clinical benefits and increased toxicity with abiraterone acetate plus prednisone administration in the fed state underscore the importance of adhering to current dosing recommendations.

Phase Ib dose-finding study of abiraterone acetate plus buparlisib (BKM120) or dactolisib (BEZ235) in patients with castration-resistant prostate cancer

BACKGROUND

The phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signalling axis and androgen receptor (AR) pathways exhibit reciprocal feedback regulation in phosphatase and tensin homologue (PTEN)-deficient metastatic castration-resistant prostate cancer (CRPC) in preclinical models. This phase Ib study evaluated the pan-PI3K inhibitor buparlisib (BKM120) and the dual pan-PI3K/ mammalian target of rapamycin (mTOR) inhibitor dactolisib (BEZ235) in combination with abiraterone acetate (AA) in patients with CRPC.

MATERIALS AND METHODS

Patients with CRPC who had progressed on AA therapy received escalating doses of either buparlisib or dactolisib, along with fixed doses of AA (1000 mg once daily (qd)) and prednisone (5 mg twice daily (bid)). The primary objective was to define the maximum tolerated dose (MTD) and/or the recommended dose for expansion (RDE) of either buparlisib or dactolisib in combination with AA. Secondary objectives included safety, antitumour activity (Prostate Cancer Working Group 2 (PCWG2) criteria; 30% of prostate-specific antigen (PSA) decline at ≥week 12) and pharmacokinetic (PK) profile.

RESULTS

In buparlisib + AA arm, 25 patients received buparlisib + AA (median age, 67 years; Eastern Cooperative Oncology Group performance status (ECOG PS) of 0/1/2 for 7/17/1 patients, respectively). At 100 mg qd; two patients experienced dose-limiting toxicities (DLTs) (grade 3 hyperglycaemia; grade 2 asthenia), and this was the maximum buparlisib dose explored. Buparlisib + AA showed a 26% lower median area under the curve from time zero to 24°h (AUC_0-24) and 48% lower median maximum serum concentration (Cmax) versus the single-agent buparlisib assessed in first-in-human study. No objective response and few PSA decreases were reported. In dactolisib + AA arm, 18 patients (median age, 71 years; ECOG PS of 0/1 for 6/12 patients, respectively) received dactolisib + AA at the first dose level (200 mg bid). Five patients had 9 DLTs (grades 2&3 stomatitis; grade 3 hyperglycaemia; grades 2& 3 diarrhoea; grades 1& 2 pyrexia, grade 2 vomiting, and grade 2 chills).

CONCLUSIONS

Based on the assessment of available pharmacokinetics, safety, and efficacy data, no further study is planned for either buparlisib or dactolisib in combination with AA in CRPC.

Androgen receptor is a potential novel prognostic marker and oncogenic target in osteosarcoma with dependence on CDK11

Osteosarcoma is the most common bone cancer in children and adolescents. Previously, we have found that cyclin-dependent kinase 11 (CDK11) signaling was essential for osteosarcoma cell growth and survival. Subsequently, CDK11 siRNA gene targeting, expression profiling, and network reconstruction of differentially expressed genes were performed between CDK11 knock down and wild type osteosarcoma cells. Reconstructed network of the differentially expressed genes pointed to the AR as key to CDK11 signaling in osteosarcoma. CDK11 increased transcriptional activation of AR gene in osteosarcoma cell lines. AR protein was highly expressed in various osteosarcoma cell lines and patient tumor tissues. Tissue microarray analysis showed that the disease-free survival rate for patients with high-expression of AR was significantly shorter than for patients with low-expression of AR. In addition, AR gene expression knockdown via siRNA greatly inhibited cell growth and viability. Similar results were found in osteosarcoma cells treated with AR inhibitor. These findings suggest that CDK11 is involved in the regulation of AR pathway and AR can be a potential novel prognostic marker and therapeutic target for osteosarcoma treatment.

Safety and Antitumour Activity of ODM-201 (BAY-1841788) in Castration-resistant, CYP17 Inhibitor-naïve Prostate Cancer: Results from Extended Follow-up of the ARADES Trial

BACKGROUND

Patients with castration-resistant prostate cancer (CRPC) had extended responses to the androgen receptor antagonist ODM-201, in phase 1/2 studies.

OBJECTIVE

To evaluate the safety and antitumour activity of prolonged ODM-201 treatment in patients with CRPC.

DESIGN, SETTING, AND PARTICIPANTS

The ARADES trial was a multicentre phase 1 (dose escalation) and phase 2 (dose expansion) trial; 134 patients with CRPC were stratified by previous chemotherapy to receive ODM-201. This paper reports extended follow-up in CYP17 inhibitor (CYP17i)-naïve patients.

INTERVENTION

Patients (n=77) received oral ODM-201 twice daily at daily doses of 200-1800mg.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Safety, measured as the occurrence of adverse events (AEs), prostate-specific antigen (PSA), and radiographic progression.

RESULTS AND LIMITATIONS

The safety profile of extended ODM-201 treatment (median treatment duration 8.2 mo, 95% confidence interval [CI] 5.6-11.0) was consistent with that reported at the time of the original data cutoff in the main ARADES trial, with no unexpected safety concerns over time. The majority of AEs (61.1%) were mild (grade 1); the most common AE was fatigue/asthenia (35.1% of patients), with no clear relationship to ODM-201. Median time to PSA progression was 25.2 mo (95% CI 11.3-25.2) for chemotherapy-naïve men and not reached (NR; 95% CI 5.5-NR) for chemotherapy-pretreated patients; a trend for improved antitumour response was observed for chemotherapy-naïve patients. The median time to radiographic progression was longer for chemotherapy-naïve (14.0 mo, 95% CI 8.1-33.3) than for chemotherapy-pretreated (7.2 mo, 95% CI 2.7-11.0) patients.

CONCLUSIONS

Prolonged exposure to ODM-201 was well tolerated, with no additional safety concerns; disease suppression was sustained, especially in chemotherapy-naïve patients. These data support further development of ODM-201 in men with CYP17i-naïve CRPC.

PATIENT SUMMARY

Extended ODM-201 therapy was well tolerated, with beneficial antitumour activity in men with advanced prostate cancer, indicating that ODM-201 may represent a new active treatment for men with CRPC. This extension trial is registered at ClinicalTrials.gov (www.clinicaltrials.gov) under identification number NCT01429064.

Indirect comparison between abiraterone acetate and enzalutamide for the treatment of metastatic castration-resistant prostate cancer: a systematic review

This study was designed to evaluate the efficacy, tolerability, and sequential administration of abiraterone acetate (AA) and enzalutamide (Enz) for metastatic castration-resistant prostate cancer (mCRPC). A literature search was performed with PubMed, Embase, and Web of Science databases to identify relevant studies. Reviewed literature included published phase III trials of AA or Enz in mCRPC and studies regarding their sequential administration. Given the difference in control arms in AA (active comparator) and Enz (true placebo) randomized phase III studies, indirect comparisons between AA and Enz in mCRPC showed no statistically significant difference in overall survival in prechemotherapy and postchemotherapy settings (HR: 0.90, 95% CI, 0.73-1.11; HR: 0.85, 95% CI, 0.68-1.07). Compared with AA, Enz may better outperform control arms in treating mCRPC both before and after chemotherapy regarding secondary endpoints based on indirect comparisons: time to prostate-specific antigen (PSA) progression (HR: 0.34, 95% CI, 0.28-0.42; HR: 0.40, 95% CI, 0.30-0.53), radiographic progression-free survival (HR: 0.37, 95% CI, 0.28-0.48; HR: 0.61, 95% CI, 0.50-0.74), and PSA response rate (OR: 18.29, 95% CI, 11.20-29.88; OR: 10.69, 95% CI, 3.92-29.20). With regard to the effectiveness of Enz following AA or AA following Enz, recent retrospective case series reported overall survival and secondary endpoints for patients with mCRPC progression after chemotherapy. However, confirmatory head-to-head trials are necessary to determine the optimal sequencing of these agents.