Second-Generation Androgen Receptor Antagonists as Hormonal Therapeutics for Three Forms of Prostate Cancer

Exploring skin adverse events and mechanisms of apalutamide using data mining algorithms and network pharmacology

Background

Skin adverse events of apalutamide pose a major challenge to its clinical use, particularly the severe and difficult to identify toxic epidermal necrolysis. For the purpose of providing the basis for the clinical monitoring of the administration of apalutamide and further research. This study examined the pathways of apalutamide and Stephen Johnson Syndrome/Toxic Epidermal Necrolysis using network pharmacology and data mining tools to analyze skin adverse events.

Methods

Using the Information Component method and the Reporting Odds Ratio, the relationship between apalutamide and skin adverse events was evaluated. Molecular docking was utilized to explore the potential mechanism of apalutamide and Stephen Johnson Syndrome/toxic epidermal necrolysis.

Results

With a median time to onset of all skin adverse events of 55 days, a total of 21 skin-related adverse events were found. Low body weight and advanced age may be major hazards for skin adverse events with apalutamide. The results showed a substantial association between apalutamide and Stephen Johnson Syndrome/toxic epidermal necrolysis, and the mechanism behind this association may be the binding of apalutamide to JAK1 and JAK2.

Conclusion

Special attention is recommended for skin adverse events when using apalutamide, especially for rapidly progressing and severe adverse events. To confirm the connection between the triad of Janus kinase, apalutamide, and skin adverse events, further research is required in the future.

Intramolecular Cascade Cyclization of Cyclobutanone: Asymmetric Construction of Cyclobutanone Fused Oxa-Spirocycles

The successful implementation of a cascade reaction involving a cyclobutyl unit has posed a significant challenge in achieving ring-retentive functionalization because of the ring's sacrificial tendency. Herein, we have accomplished a cinchona-derived squaramide-catalyzed cascade reaction sequence, encompassing the desymmetrization of cyclobutanone, followed by an aldol reaction and, subsequently, a 1,4-addition step. This overall process offers a viable strategy to access architecturally fascinating oxa-spirocycles fused with cyclobutanone motifs in good yields with high optical purity.

A high-throughput platform for single-molecule tracking identifies drug interaction and cellular mechanisms

The regulation of cell physiology depends largely upon interactions of functionally distinct proteins and cellular components. These interactions may be transient or long-lived, but often affect protein motion. Measurement of protein dynamics within a cellular environment, particularly while perturbing protein function with small molecules, may enable dissection of key interactions and facilitate drug discovery; however, current approaches are limited by throughput with respect to data acquisition and analysis. As a result, studies using super-resolution imaging are typically drawing conclusions from tens of cells and a few experimental conditions tested. We addressed these limitations by developing a high-throughput single-molecule tracking (htSMT) platform for pharmacologic dissection of protein dynamics in living cells at an unprecedented scale (capable of imaging >106 cells/day and screening >104 compounds). We applied htSMT to measure the cellular dynamics of fluorescently tagged estrogen receptor (ER) and screened a diverse library to identify small molecules that perturbed ER function in real time. With this one experimental modality, we determined the potency, pathway selectivity, target engagement, and mechanism of action for identified hits. Kinetic htSMT experiments were capable of distinguishing between on-target and on-pathway modulators of ER signaling. Integrated pathway analysis recapitulated the network of known ER interaction partners and suggested potentially novel, kinase-mediated regulatory mechanisms. The sensitivity of htSMT revealed a new correlation between ER dynamics and the ability of ER antagonists to suppress cancer cell growth. Therefore, measuring protein motion at scale is a powerful method to investigate dynamic interactions among proteins and may facilitate the identification and characterization of novel therapeutics.

Extracellular vesicles derived-microRNAs predicting enzalutamide-resistance in 3D spheroid prostate Cancer model

Enzalutamide (ENZ) has emerged as a major treatment advance in castration-resistant prostate cancer (CRPC) patients; however the development of resistance remains a key challenge. The extracellular vesicles (VEs)-derived miRNAs play crucial roles tumor microenvironment cell communication, thereby influencing resistance mechanisms. Considering the urgent need for molecular biomarkers to monitor ENZ response and predict resistance, we intend to identify an EV-derived miRNA profile associated with ENZ resistance using an innovative 3D-spheroid in vitro model. Through the generation of this model, we provide a comprehensive platform for elucidating the molecular alterations involved in the process. An in vitro model of ENZ resistance was established through continuous exposure of LNCaP to increasing ENZ concentrations. A screening of 799 miRNAs from resistant and normal LNCaP cells were quantified. A bioinformatic analysis was performed using miRTarbase and Cytoscape and top 5 overexpressed miRNAs were selected, that will be analyzed in extracellular vesicles derived from ENZ resistance 3D spheroid models. We identified 12 up- and 13 downregulated miRNAs in LNCaP 30 μM ENZ cells compare to LNCaP·In silico analysis led to the construction of a 76 proteins cluster and functional enrichment revealed terms like PI3K/AKT, TFG-β and FOXO. hsa-miR-22-3p was significantly decreased at 5 and 20 μM ENZ concentration intracellularly, but significantly increased at 20 μM ENZ in EVs. hsa-miR-221-3p and miR-222-3p were upregulated in all concentrations both intracellularly and in EVs. The developed 3D-spheroid model effectively replicated the ENZ resistance to ENZ in an AR-independent manner, underscoring the importance of EVs-derived miRNAs in this adaptive process.

The design, synthesis and bioactivity evaluation of novel androgen receptor degraders based on hydrophobic tagging

Prostate Cancer (PCa) easily progress to metastatic Castration-Resistant Prostate Cancer (mCRPC) that remains a significant cause of cancer-related death. Androgen receptor (AR)-dependent transcription is a major driver of prostate tumor cell proliferation. Proteolysis-targeting chimaera (PROTAC) technology based on Hydrophobic Tagging (HyT) represents an intriguing strategy to regulate the function of therapeutically androgen receptor proteins. In the present study, we have designed, synthesized, and evaluated a series of PROTAC-HyT AR degraders using AR antagonists, RU59063, which were connected with adamantane-based hydrophobic moieties by different alkyl chains. Compound D-4-6 exhibited significant AR protein degradation activity, with a degradation rate of 57 % at 5 μM and nearly 90 % at 20 μM in 24 h, and inhibited the proliferation of LNCaP cells significantly with an IC50 value of 4.77 ± 0.26 μM in a time-concentration-dependent manner. In conclusion, the present study lays the foundation for the development of a completely new class of therapeutic agents for the treatment of mCRPC, and further design and synthesis of AR-targeting degraders are currently in progress for better degradation rate.

Exploring the molecular mechanisms by which per- and polyfluoroalkyl substances induce polycystic ovary syndrome through in silico toxicogenomic data mining

The pathogeny of polycystic ovary syndrome (PCOS) is intricate, with endocrine disruptors (EDCs) being acknowledged as significant environmental factors. Research has shown a link between exposure to per- and polyfluoroalkyl substances (PFAS) and the development and progression of PCOS, although the precise mechanism is not fully understood. This study utilized toxicogenomics and comparative toxicogenomics databases to analyze data and investigate how PFAS mixtures may contribute to the development of PCOS. The results indicated that 74 genes are associated with both PFAS exposure and PCOS progression. Enrichment analysis suggested that cell cycle regulation and steroid hormone synthesis may be crucial pathways through which PFAS mixtures participate in the development of PCOS, involving important genes such as CCNB1 and SRD5A1. Furthermore, the study identified transcription factors (TFs) and miRNAs that may be involved in the onset and progression of PCOS, constructing regulatory networks encompassing TFs-mRNA interactions and miRNA-mRNA relationships to elucidate their regulatory roles in gene expression. By utilizing data mining techniques based on toxicogenomic databases, this study provides relatively comprehensive insights into the association between exposure factors and diseases compared to traditional toxicology studies. These findings offer new perspectives for further in vivo or in vitro investigations and contribute to understanding the pathogenesis of PCOS, thereby providing valuable references for identifying clinical treatment targets.

Treatment intensification strategies for men undergoing definitive radiotherapy for high-risk prostate cancer

PURPOSE

Treatment intensification of external beam radiotherapy (EBRT) plays a crucial role in the treatment of high-risk prostate cancer.

METHODS

We performed a critical narrative review of the relevant literature and present new developments in evidence-based treatment intensification strategies.

RESULTS

For men with high-risk prostate cancer, there is strong evidence to support prolonging androgen deprivation therapy (ADT) to 18-36 months and escalating the dose to the prostate using a brachytherapy boost. A potentially less toxic alternative to a brachytherapy boost is delivering a focal boost to dominant intraprostatic lesions using EBRT. In patients who meet STAMPEDE high-risk criteria, there is evidence to support adding a second-generation anti-androgen agent, such as abiraterone acetate, to long-term ADT. Elective pelvic lymph node irradiation may be beneficial in select patients, though more prospective data is needed to elucidate the group of patients who may benefit the most. Tumor genomic classifier (GC) testing and advanced molecular imaging will likely play a role in improving patient selection for treatment intensification as well as contribute to the evolution of treatment intensification strategies for future patients.

CONCLUSION

Treatment intensification using a combination of EBRT, advanced hormonal therapies, and brachytherapy may improve patient outcomes and survival in men with high-risk prostate cancer. Shared decision-making between patients and multidisciplinary teams of radiation oncologists, urologists, and medical oncologists is essential for personalizing care in this setting and deciding which strategies make sense for individual patients.

Insight into Recent Advances in Degrading Androgen Receptor for Castration-Resistant Prostate Cancer

Induced protein degradation has emerged as an innovative drug discovery approach, complementary to the classical method of suppressing protein function. The androgen receptor signaling pathway has been identified as the primary driving force in the development and progression of lethal castration-resistant prostate cancer. Since androgen receptor degraders function differently from androgen receptor antagonists, they hold the promise to overcome the drug resistance challenges faced by current therapeutics. Proteolysis-targeting chimeras (PROTACs), monomeric degraders, hydrophobic tagging, molecular glues, and autophagic degradation have demonstrated their capability in downregulating intracellular androgen receptor concentrations. The potential of these androgen receptor degraders to treat castration-resistant prostate cancer is substantiated by the advancement of six PROTACs and two monomeric androgen receptor degraders into phase I or II clinical trials. Although the chemical structures, in vitro and in vivo data, and degradation mechanisms of androgen receptor degraders have been reviewed, it is crucial to stay updated on recent advances in this field as novel androgen receptor degraders and new strategies continue to emerge. This review thus provides insight into recent advancements in this paradigm, offering an overview of the progress made since 2020.

IU1 and enzalutamide combination yields synergistic effects on castration-resistant prostate cancer

BACKGROUND

Androgen deprivation therapy (ADT) is one of the main treatment modalities for prostate cancer (PCa); however, almost all patients treated with ADT eventually progress into castration-resistant PCa (CRPC). Although second-generation androgen receptor (AR) antagonists, such as enzalutamide, have been approved for CRPC treatment, AR signaling in CRPC cells is reactivated through multiple mechanisms, resulting in resistance to treatment and tumor progression with a very poor prognosis. The present study aimed to explore the anticancer effect of a treatment combining AR antagonist enzalutamide with AR degrader IU1 on PCa cells.

METHODS

The joint effects of enzalutamide and IU1 on PCa cell proliferation and apoptosis and associated cell signaling were evaluated in vitro. Mechanistically, the ubiquitination level and half-life of AR were examined under the combination treatment. The binding of IU1 and enzalutamide to AR was further verified using cellular thermal shift analysis and isothermal dose-response curve fingerprinting.

RESULTS

The combination of IU1 and three AR antagonists showed synergistic effects in different prostate cell lines. IU1 and enzalutamide synergistically promoted the degradation of AR and AR-V7 proteins, as well as suppressed the expression levels of AR and AR-V7 downstream target genes at the transcriptional and protein levels. The combination also synergistically blocked the PCa cell cycle and promoted apoptosis in PCa cell lines. Mechanistically, the combination promoted increased levels of AR ubiquitination. In CRPC cell lines and in the presence of increased androgen concentrations, enzalutamide was still able to bind AR competitively with androgens, reducing the stability of AR and thus promoting the degradation effect of IU1 on AR, synergistically producing an inhibitory effect on PCa cells.

CONCLUSION

Taken together, our findings suggest that the combination of AR degrader and enzalutamide potentially represents a new therapeutic strategy for CRPC.

Beyond Prostate Cancer: An Androgen Receptor Splice Variant Expression in Multiple Malignancies, Non-Cancer Pathologies, and Development

Multiple studies have demonstrated the importance of androgen receptor (AR) splice variants (SVs) in the progression of prostate cancer to the castration-resistant phenotype and their utility as a diagnostic. However, studies on AR expression in non-prostatic malignancies uncovered that AR-SVs are expressed in glioblastoma, breast, salivary, bladder, kidney, and liver cancers, where they have diverse roles in tumorigenesis. AR-SVs also have roles in non-cancer pathologies. In granulosa cells from women with polycystic ovarian syndrome, unique AR-SVs lead to an increase in androgen production. In patients with nonobstructive azoospermia, testicular Sertoli cells exhibit differential expression of AR-SVs, which is associated with impaired spermatogenesis. Moreover, AR-SVs have been identified in normal cells, including blood mononuclear cells, neuronal lipid rafts, and the placenta. The detection and characterization of AR-SVs in mammalian and non-mammalian species argue that AR-SV expression is evolutionarily conserved and that AR-SV-dependent signaling is a fundamental regulatory feature in multiple cellular contexts. These discoveries argue that alternative splicing of the AR transcript is a commonly used mechanism that leads to an expansion in the repertoire of signaling molecules needed in certain tissues. Various malignancies appropriate this mechanism of alternative AR splicing to acquire a proliferative and survival advantage.

Tricyclic Diterpenoids Selectively Suppress Androgen Receptor-Positive Prostate Cancer Cells

Androgen receptor (AR) is a viable therapeutic target for lethal castration-resistant prostate cancer (CRPC), because the continued progression of CRPC is mainly driven by the reactivation of AR transcriptional activity. The current FDA-approved AR antagonists binding to ligand binding domain (LBD) become ineffective in CRPC with AR gene amplification, LBD mutation, and the evolution of LBD-truncated AR splice variants. Encouraged by the fact that tricyclic aromatic diterpenoid QW07 has recently been established as a potential N-terminal AR antagonist, this study aims to explore the structure-activity relationship of tricyclic diterpenoids and their potential to suppress AR-positive cell proliferation. Dehydroabietylamine, abietic acid, dehydroabietic acid, and their derivatives were selected, since they have a similar core structure as QW07. Twenty diterpenoids were prepared for the evaluation of their antiproliferative potency on AR-positive prostate cancer cell models (LNCaP and 22Rv1) using AR-null cell models (PC-3 and DU145) as comparisons. Our data indicated that six tricyclic diterpenoids possess greater potency than enzalutamide (FDA-approved AR antagonist) towards LNCaP and 22Rv1 AR-positive cells, and four diterpenoids are more potent than enzalutamide against 22Rv1 AR-positive cells. The optimal derivative possesses greater potency (IC50 = 0.27 µM) and selectivity than QW07 towards AR-positive 22Rv1 cells.

Darolutamide for non-metastatic castration-resistant prostate cancer: Efficacy, safety, and clinical perspectives of use

Darolutamide, a second-generation androgen receptor inhibitor (SGARI), has been shown to increase metastasis-free survival and overall survival among men with non-metastatic castration-resistant prostate cancer (nmCRPC). Its unique chemical structure potentially provides efficacy and safety advantages over the SGARIs apalutamide and enzalutamide, which are also indicated for nmCRPC. Despite a lack of direct comparisons, the SGARIs appear to have similar efficacy, safety, and quality of life (QoL) results. Indirect evidence suggests that darolutamide is preferred for its good adverse event profile, an attribute valued by physicians, patients, and their caregivers for maintaining QoL. Darolutamide and others in its class are costly; access may be a challenge for many patients and may lead to modifications to guideline-recommended regimens.

Cheminformatic Analysis and Machine Learning Modeling to Investigate Androgen Receptor Antagonists to Combat Prostate Cancer

Prostate cancer (PCa) is a major leading cause of mortality of cancer among males. There have been numerous studies to develop antagonists against androgen receptor (AR), a crucial therapeutic target for PCa. This study is a systematic cheminformatic analysis and machine learning modeling to study the chemical space, scaffolds, structure-activity relationship, and landscape of human AR antagonists. There are 1678 molecules as final data sets. Chemical space visualization by physicochemical property visualization has demonstrated that molecules from the potent/active class generally have a mildly smaller molecular weight (MW), octanol-water partition coefficient (log P), number of hydrogen-bond acceptors (nHA), number of rotatable bonds (nRot), and topological polar surface area (TPSA) than molecules from intermediate/inactive class. The chemical space visualization in the principal component analysis (PCA) plot shows significant overlapping distributions between potent/active class molecules and intermediate/inactive class molecules; potent/active class molecules are intensively distributed, while intermediate/inactive class molecules are widely and sparsely distributed. Murcko scaffold analysis has shown low scaffold diversity in general, and scaffold diversity of potent/active class molecules is even lower than intermediate/inactive class molecules, indicating the necessity for developing molecules with novel scaffolds. Furthermore, scaffold visualization has identified 16 representative Murcko scaffolds. Among them, scaffolds 1, 2, 3, 4, 7, 8, 10, 11, 15, and 16 are highly favorable scaffolds due to their high scaffold enrichment factor values. Based on scaffold analysis, their local structure-activity relationships (SARs) were investigated and summarized. In addition, the global SAR landscape was explored by quantitative structure-activity relationship (QSAR) modelings and structure-activity landscape visualization. A QSAR classification model incorporating all of the 1678 molecules stands out as the best model from a total of 12 candidate models for AR antagonists (built on PubChem fingerprint, extra trees algorithm, accuracy for training set: 0.935, 10-fold cross-validation set: 0.735 and test set: 0.756). Deeper insights into the structure-activity landscape highlighted a total of seven significant activity cliff (AC) generators (ChEMBL molecule IDs: 160257, 418198, 4082265, 348918, 390728, 4080698, and 6530), which provide valuable SAR information for medicinal chemistry. The findings in this study provide new insights and guidelines for hit identification and lead optimization for the development of novel AR antagonists.

Distinct mechanisms mediating therapy-induced cellular senescence in prostate cancer

BACKGROUND

Prostate cancer (PCa) is an age-related malignancy in men with a high incidence rate. PCa treatments face many obstacles due to cancer cell resistance and many bypassing mechanisms to escape therapy. According to the intricacy of PCa, many standard therapies are being used depending on PCa stages including radical prostatectomy, radiation therapy, androgen receptor (AR) targeted therapy (androgen deprivation therapy, supraphysiological androgen, and AR antagonists) and chemotherapy. Most of the aforementioned therapies have been implicated to induce cellular senescence. Cellular senescence is defined as a stable cell cycle arrest in the G1 phase and is one of the mechanisms that prevent cancer proliferation.

RESULTS

In this review, we provide and analyze different mechanisms of therapy-induced senescence (TIS) in PCa and their effects on the tumor. Interestingly, it seems that different molecular pathways are used by cancer cells for TIS. Understanding the complexity and underlying mechanisms of cellular senescence is very critical due to its role in tumorigenesis. The most prevalent analyzed pathways in PCa as TIS are the p53/p21^WAF1/CIP1, the p15^INK4B/p16^INK4A/pRb/E2F/Cyclin D, the ROS/ERK, p27^Kip1/CDK/pRb, and the p27^Kip1/Skp2/C/EBP β signaling. Despite growth inhibition, senescent cells are highly metabolically active. In addition, their secretome, which is termed senescence-associated secretory phenotype (SASP), affects within the tumor microenvironment neighboring non-tumor and tumor cells and thereby may regulate the growth of tumors. Induction of cancer cell senescence is therefore a double-edged sword that can lead to reduced or enhanced tumor growth.

CONCLUSION

Thus, dependent on the type of senescence inducer and the specific senescence-induced cellular pathway, it is useful to develop pathway-specific senolytic compounds to specifically targeting senescent cells in order to evict senescent cells and thereby to reduce SASP side effects.

Constitutively Active Androgen Receptor in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the predominant type of liver cancer and a leading cause of cancer-related death globally. It is also a sexually dimorphic disease with a male predominance both in HCC and in its precursors, non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH). The role of the androgen receptor (AR) in HCC has been well documented; however, AR-targeted therapies have failed to demonstrate efficacy in HCC. Building upon understandings of AR in prostate cancer (PCa), this review examines the role of AR in HCC, non-androgen-mediated mechanisms of induced AR expression, the existence of AR splice variants (AR-SV) in HCC and concludes by surveying current AR-targeted therapeutic approaches in PCa that show potential for efficacy in HCC in light of AR-SV expression.

Current strategies and progress for targeting the "undruggable" transcription factors

Transcription factors (TFs) specifically bind to DNA, recruit cofactor proteins and modulate target gene expression, rendering them essential roles in the regulation of numerous biological processes. Meanwhile, mutated or dysregulated TFs are involved in a variety of human diseases. As multiple signaling pathways ultimately converge at TFs, targeting these TFs directly may prove to be more specific and cause fewer side effects, than targeting the upfront conventional targets in these pathways. All these features together endue TFs with great potential and high selectivity as therapeutic drug targets. However, TFs have been historically considered "undruggable", mainly due to their lack of structural information, especially about the appropriate ligand-binding sites and protein-protein interactions, leading to relatively limited choices in the TF-targeting drug design. In this review, we summarize the recent progress of TF-targeting drugs and highlight certain strategies used for targeting TFs, with a number of representative drugs that have been approved or in the clinical trials as examples. Various approaches in targeting TFs directly or indirectly have been developed. Common direct strategies include aiming at defined binding pockets, proteolysis-targeting chimaera (PROTAC), and mutant protein reactivation. In contrast, the indirect ones comprise inhibition of protein-protein interactions between TF and other proteins, blockade of TF expression, targeting the post-translational modifications, and targeting the TF-DNA interactions. With more comprehensive structural information about TFs revealed by the powerful cryo-electron microscopy technology and predicted by machine-learning algorithms, plus more efficient compound screening platforms and a deeper understanding of TF-disease relationships, the development of TF-targeting drugs will certainly be accelerated in the near future.

Phase Ib Study of the BET Inhibitor GS-5829 as Monotherapy and Combined with Enzalutamide in Patients with Metastatic Castration-Resistant Prostate Cancer

PURPOSE

A phase Ib study (1604) was conducted to evaluate the safety and efficacy of GS-5829, an oral bromodomain and extraterminal inhibitor, alone and in combination with enzalutamide in metastatic castration-resistant prostate cancer (mCRPC). A phase I study (1599) in solid tumors/lymphoma was also conducted.

PATIENTS AND METHODS

Men with confirmed mCRPC and disease progression despite abiraterone and/or enzalutamide treatment were enrolled in a 3 + 3 dose escalation paradigm starting at 2 mg daily with GS-5829 alone and in combination with 160 mg daily enzalutamide. The primary efficacy endpoint was nonprogression rate at week 24; secondary endpoints included prostate-specific antigen reduction from baseline, progression-free survival, and GS-5829 pharmacokinetics (PK). PK and safety were also evaluated in Study 1599.

RESULTS

Thirty-one men, with a median of five prior regimens, received at least 1 dose of study drug in Study 1604. Treatment-emergent adverse events (TEAE) were reported in 94% of patients; 16% discontinued for TEAEs. There were no dose-dependent increases in the AUCtau or Cmax after once-daily administration of GS-5829 2 to 9 mg, and biomarkers CCR2 inhibition and HEXIM1 induction were increased only at higher doses of monotherapy. A high degree of interpatient variability existed across all doses in PK and pharmacodynamic parameters. The proportion with nonprogression at week 24, estimated by Kaplan-Meier model, was 25% (95% confidence interval, 10-42) for all treated patients.

CONCLUSIONS

GS-5829 was generally tolerated but demonstrated limited efficacy and lack of dose proportional increases in plasma concentrations in patients with mCRPC.

Second generation androgen receptor antagonists and challenges in prostate cancer treatment

Prostate cancer is a hormone-dependent malignancy, whose onset and progression are closely related to the activity of the androgen receptor (AR) signaling pathway. Due to this critical role of AR signaling in driving prostate cancer, therapy targeting the AR pathway has been the mainstay strategy for metastatic prostate cancer treatment. The utility of these agents has expanded with the emergence of second-generation AR antagonists, which began with the approval of enzalutamide in 2012 by the United States Food and Drug Administration (FDA). Together with apalutamide and darolutamide, which were approved in 2018 and 2019, respectively, these agents have improved the survival of patients with prostate cancer, with applications for both androgen-dependent and castration-resistant disease. While patients receiving these drugs receive a benefit in the form of prolonged survival, they are not cured and ultimately progress to lethal neuroendocrine prostate cancer (NEPC). Here we summarize the current state of AR antagonist development and highlight the emerging challenges of their clinical application and the potential resistance mechanisms, which might be addressed by combination therapies or the development of novel AR-targeted therapies.

Therapeutic Strategies to Target the Androgen Receptor

The androgen receptor (AR) plays a key role in the maintenance of muscle and bone and the support of male sexual-related functions, as well as in the progression of prostate cancer. Accordingly, AR-targeted therapies have been developed for the treatment of related human diseases and conditions. AR agonists are an important class of drugs in the treatment of bone loss and muscle atrophy. AR antagonists have also been developed for the treatment of prostate cancer, including metastatic castration-resistant prostate cancer (mCRPC). Additionally, selective AR degraders (SARDs) have been reported. More recently, heterobifunctional degrader molecules of AR have been developed, and four such compounds are now in clinical development for the treatment of human prostate cancer. This review attempts to summarize the different types of compounds designed to target AR and the current frontiers of research on this important therapeutic target.

Synthesis and biological evaluation of niclosamide PROTACs

Roughly 268,000 new cases of prostate cancer and 34,000 deaths from prostate cancer are projected by the American Cancer Society to occur in the United States in 2022. Androgen receptor is a key protein in the proliferation and survival of prostate cancer cells and has been revealed to be overexpressed in 30% to 50% of castration-resistant prostate cancer patients. One promising approach to reducing the level of this protein is Proteolysis Targeting Chimeras (PROTACs) that is an emerging drug discovery technology. PROTACs are hetero-bifunctional molecules where one end binds to a protein of interest and the other to an E3 ligase ligand, initiating the Ubiquitin-Proteasome Pathway for protein degradation. Two PROTACs with niclosamide as androgen receptor ligand and VHL-032 as the E3 ligase ligand have been designed and synthesized for suppressing proliferation of androgen receptor-positive prostate cancer cells via degrading androgen receptor. The in vitro antiproliferative assessment suggested that they can selectively suppress PC-3, LNCaP, and 22Rv1 prostate cancer cell proliferation, but cannot inhibit DU145 cell proliferation. However, the mechanism of both compounds in suppressing prostate cancer cell proliferation is not through the AR PROTAC mechanism because they did not degrade AR in our Western Blotting assay up to 1 µM.

Multidisciplinary Consensus on the Prevention and Treatment of Osteoporosis and Fragility Fractures in Patients with Prostate Cancer Receiving Androgen-Deprivation Therapy

Patients with prostate cancer (PCa) on androgen-deprivation therapy (ADT) are at high risk of osteoporosis and fragility fractures. We aimed to provide some practical insights into the delivery of optimal bone health care for PCa patients, particularly those on ADT. An interdisciplinary group of experts, including urologists and rheumatologists developed recommendations based on their expertise, current evidence and guidelines. The multidisciplinary group's main recommendations are: fragility fracture risk should be assessed in all PCa patient, especially, in those under ADT. FRAX® tool may be incorporated into clinical practice to identify patients at high risk of fracture. Bone mineral density (BMD) should be measured routinely by dual energy X-ray absorptiometry in all patients scheduled for or on ADT. Thoracic and lumbar spine X-ray may be performed at the initial evaluation of patients with the diagnosis of osteoporosis and in case of suspected clinical vertebral fracture. Basic laboratory tests are recommended to exclude secondary osteoporosis. Treatment with bisphosphonates or denosumab should be considered in patients on ADT with fragility fracture, osteoporosis (BMD T-score ≤-2.5), or high risk of fracture according to FRAX®. Referral to a bone metabolism specialist should be contemplated in some cases. The recommendations provided in this document, tailored for clinicians treating PCa patients, may be of help to identify and treat patients at high risk of fracture.

Medication adherence among patients with advanced prostate cancer using oral therapies

Aims: In light of the extended overall survival and improved quality of life provided by advanced prostate cancer (PC) oral therapies, this study aimed to describe treatment adherence to advanced PC oral therapies and evaluate associated patient characteristics and subsequent healthcare resource utilization (HRU). Patients & methods: Patients with advanced PC initiating apalutamide, enzalutamide or abiraterone acetate were identified from administrative data (October 1, 2014-September 30, 2019). Adherence and persistence at six months postinitiation were used to evaluate patient factors and HRU. Results: Aged ≥75 years, Black race, chemotherapy use and higher pharmacy paid amounts were associated with poor adherence/persistence, which translated to higher HRU. Conclusions: Strategies to increase adherence and persistence may improve patient outcomes and associated HRU.

Pathological significance and prognostic role of LATS2 in prostate cancer

BACKGROUND

Large tumor suppressor 2 (LATS2) is an important regulator of the Hippo pathway and it plays crucial roles in cell survival and behaviors. Herein, we evaluated the pathological roles of LATS2 in prostate cancer (PC), for which very little information is available.

METHODS

Cell proliferation, migration, and invasion in response to the siRNA-mediated knockdown (KD) LATS2 expression were evaluated in two PC cell lines (LNCaP and PC3). The expression of LATS2 in specimens from 204 PC patients was investigated immunohistochemically, and the relationships between its expression and clinicopathological features, proliferation index (PI; measured using an anti-KI-67 antibody), and biochemical recurrence (BCR) were investigated.

RESULTS

KD of LATS2 increased the growth, migration, and invasion in LNCaP cells and only increased migration in PC3 cells. The expression of LATS2 was negatively associated with the grade group, T, N, M stage, and PI. In addition, the expression of LATS2 was a useful predictor of the histological effects of neoadjuvant hormonal therapy and BCR-free survival periods. A multivariate analysis model including clinicopathological features showed that negative expression of LATS2 had a significantly higher risk of BCR (odds ratio = 2.95, P < 0.001).

CONCLUSIONS

LATS2 acts as a tumor suppressor in PC. LATS2 expression is a useful predictor for BCR. LATS2-related activities are possibly dependent on the androgen-dependency of PC cells. Therefore, we suggest that LATS2 could be a potential therapeutic target and a useful predictor for outcome in patients with PC.

3-O-Carbamoyl-5,7,20-O-trimethylsilybins: Synthesis and Preliminary Antiproliferative Evaluation

To search for novel androgen receptor (AR) modulators for the potential treatment of castration-resistant prostate cancer (CRPC), naturally occurring silibinin was sought after as a lead compound because it possesses a moderate potency towards AR-positive prostate cancer cells and its chemical scaffold is dissimilar to all currently marketed AR antagonists. On the basis of the structure-activity relationships that we have explored, this study aims to incorporate carbamoyl groups to the alcoholic hydroxyl groups of silibinin to improve its capability in selectively suppressing AR-positive prostate cancer cell proliferation together with water solubility. To this end, a feasible approach was developed to regioselectively introduce a carbamoyl group to the secondary alcoholic hydroxyl group at C-3 without causing the undesired oxidation at C2-C3, providing an avenue for achieving 3-O-carbamoyl-5,7,20-O-trimethylsilybins. The application of the synthetic method can be extended to the synthesis of 3-O-carbamoyl-3',4',5,7-O-tetramethyltaxifolins. The antiproliferative potency of 5,7,20-O-trimethylsilybin and its nine 3-carbamoyl derivatives were assessed in an AR-positive LNCaP prostate cancer cell line and two AR-null prostate cancer cell lines (PC-3 and DU145). Our preliminary bioassay data imply that 5,7,20-O-trimethylsilybin and four 3-O-carbamoyl-5,7,20-O-trimethylsilybins emerge as very promising lead compounds due to the fact that they can selectively suppress AR-positive LNCaP cell proliferation. The IC50 values of these five 5,7,20-O-trimethylsilybins against the LNCaP cells fall into the range of 0.11-0.83 µM, which exhibit up to 660 times greater in vitro antiproliferative potency than silibinin. Our findings suggest that carbamoylated 5,7,20-O-trimethylsilybins could serve as a natural product-based scaffold for new antiandrogens for lethal castration-resistant prostate cancer.

Nitrile-containing pharmaceuticals: target, mechanism of action, and their SAR studies

The nitrile group is an important functional group widely found in both pharmaceutical agents and natural products. More than 30 nitrile-containing pharmaceuticals have been approved by the FDA for the management of a broad range of clinical conditions in the last few decades. Incorporation of a nitrile group into lead compounds has gradually become a promising strategy in rational drug design as it can bring additional benefits including enhanced binding affinity to the target, improved pharmacokinetic profile of parent drugs, and reduced drug resistance. This paper reviews the existing drugs with a nitrile moiety that have been approved or in clinical trials, involving their targets, molecular mechanism of pharmacology and SAR studies, and classifies them into different categories based on their clinical usages.

Using ex vivo culture to assess dynamic phenotype changes in human prostate macrophages following exposure to therapeutic drugs

Within the prostate tumor microenvironment (TME) there are complex multi-faceted and dynamic communication occurring between cancer cells and immune cells. Macrophages are key cells which infiltrate and surround tumor cells and are recognized to significantly contribute to tumor resistance and metastases. Our understanding of their function in the TME is commonly based on in vitro and in vivo models, with limited research to confirm these model observations in human prostates. Macrophage infiltration was evaluated within the TME of human prostates after 72 h culture of fresh biopsies samples in the presence of control or enzalutamide. In addition to immunohistochemistry, an optimized protocol for multi-parametric evaluation of cellular surface markers was developed using flow cytometry. Flow cytometry parameters were compared to clinicopathological features. Immunohistochemistry staining for 19 patients with paired samples suggested enzalutamide increased the expression of CD163 relative to CD68 staining. Techniques to validate these results using flow cytometry of dissociated biopsies after 72 h of culture are described. In a second cohort of patients with Gleason grade group ≥ 3 prostate cancer, global macrophage expression of CD163 was unchanged with enzalutamide treatment. However, exploratory analyses of our results using multi-parametric flow cytometry for multiple immunosuppressive macrophage markers suggest subgroup changes as well as novel associations between circulating biomarkers like the neutrophil to lymphocyte ratio (NLR) and immune cell phenotype composition in the prostate TME. Further, we observed an association between B7–H3 expressing tumor-associated macrophages and the presence of intraductal carcinoma. The use of flow cytometry to evaluate ex vivo cultured prostate biopsies fills an important gap in our ability to understand the immune cell composition of the prostate TME. Our results highlight novel associations for further investigation.

Role of conformational dynamics and flexibilities in the steroid receptor-coregulator protein complex formation

Understanding of the mechanisms of actions of the steroid hormone receptor (SHR)-coregulator (CoR) protein complexes in the gene regulations has revolutionized the field of molecular endocrinology and endocrine-related oncology. The discovery and characterization of steroid receptor coactivators (SRCs) and their ability to bind various transcription factors including SHRs to coordinate the regulation of multiple target genes highlights their importance as key coregulators in various cellular signaling crosstalks as well as therapeutic target for various endocrine-related disorders specifically endocrine cancers. The dynamic nature of the SHR-CoR multi-protein complexes indicate the critical role of conformational flexibilities within specific protein(s). In recent years, the importance of conformational dynamics of the SHRs in the intramolecular and intermolecular allosteric regulations mediated via their intrinsically disordered (ID) surfaces has been highlighted. In this review article, we have discussed the importance of ID conformations within the SRCs that may also be playing an important role in the formation/deformation of multi protein complexes involving SHRs and CoRs and subsequent target gene regulation.

Chromatin-directed proteomics-identified network of endogenous androgen receptor in prostate cancer cells

Treatment of prostate cancer confronts resistance to androgen receptor (AR)-targeted therapies. AR-associated coregulators and chromatin proteins hold a great potential for novel therapy targets. Here, we employed a powerful chromatin-directed proteomics approach termed ChIP-SICAP to uncover the composition of chromatin protein network, the chromatome, around endogenous AR in castration resistant prostate cancer (CRPC) cells. In addition to several expected AR coregulators, the chromatome contained many nuclear proteins not previously associated with the AR. In the context of androgen signaling in CRPC cells, we further investigated the role of a known AR-associated protein, a chromatin remodeler SMARCA4 and that of SIM2, a transcription factor without a previous association with AR. To understand their role in chromatin accessibility and AR target gene expression, we integrated data from ChIP-seq, RNA-seq, ATAC-seq and functional experiments. Despite the wide co-occurrence of SMARCA4 and AR on chromatin, depletion of SMARCA4 influenced chromatin accessibility and expression of a restricted set of AR target genes, especially those involved in cell morphogenetic changes in epithelial-mesenchymal transition. The depletion also inhibited the CRPC cell growth, validating SMARCA4's functional role in CRPC cells. Although silencing of SIM2 reduced chromatin accessibility similarly, it affected the expression of a much larger group of androgen-regulated genes, including those involved in cellular responses to external stimuli and steroid hormone stimulus. The silencing also reduced proliferation of CRPC cells and tumor size in chick embryo chorioallantoic membrane assay, further emphasizing the importance of SIM2 in CRPC cells and pointing to the functional relevance of this potential prostate cancer biomarker in CRPC cells. Overall, the chromatome of AR identified in this work is an important resource for the field focusing on this important drug target.

Prostate Cancer Biomarkers: From diagnosis to prognosis and precision-guided therapeutics

Prostate cancer (PCa) is one of the most commonly diagnosed malignancies and among the leading causes of cancer-related death worldwide. It is a highly heterogeneous disease, ranging from remarkably slow progression or inertia to highly aggressive and fatal disease. As therapeutic decision-making, clinical trial design and outcome highly depend on the appropriate stratification of patients to risk groups, it is imperative to differentiate between benign versus more aggressive states. The incorporation of clinically valuable prognostic and predictive biomarkers is also potentially amenable in this process, in the timely prevention of metastatic disease and in the decision for therapy selection. This review summarizes the progress that has so far been made in the identification of the genomic events that can be used for the classification, prediction and prognostication of PCa, and as major targets for clinical intervention. We include an extensive list of emerging biomarkers for which there is enough preclinical evidence to suggest that they may constitute crucial targets for achieving significant advances in the management of the disease. Finally, we highlight the main challenges that are associated with the identification of clinically significant PCa biomarkers and recommend possible ways to overcome such limitations.

Synthesis and application of trifluoromethylpyridines as a key structural motif in active agrochemical and pharmaceutical ingredients

Herein, we provide a brief overview of the synthesis and applications of trifluoromethylpyridine (TFMP) and its derivatives in the agrochemical and pharmaceutical industries. Currently, the major use of TFMP derivatives is in the protection of crops from pests. Fluazifop-butyl was the first TFMP derivative introduced to the agrochemical market, and since then, more than 20 new TFMP-containing agrochemicals have acquired ISO common names. Several TFMP derivatives are also used in the pharmaceutical and veterinary industries; five pharmaceutical and two veterinary products containing the TFMP moiety have been granted market approval, and many candidates are currently undergoing clinical trials. The biological activities of TFMP derivatives are thought to be due to the combination of the unique physicochemical properties of the fluorine atom and the unique characteristics of the pyridine moiety. It is expected that many novel applications of TFMP will be discovered in the future.

Identification of patients with metastatic castration-sensitive or metastatic castration-resistant prostate cancer using administrative health claims and laboratory data

OBJECTIVE

To develop algorithms to identify metastatic castration-sensitive prostate cancer (mCSPC) patients and castration-resistant prostate cancer (mCRPC) patients, using health claims data and laboratory test results.

METHODS

A targeted literature review summarized mCSPC and mCRPC patient selection criteria previously used in real-world retrospective studies. Novel algorithms to identify mCSPC and mCRPC were developed based on diagnosis codes indicating hormone sensitivity/resistance, prostate-specific antigen (PSA) test results, and claims for castration and mCRPC-specific treatments. These algorithms were applied to claims data from Optum Clinformatics Extended DataMart (Date of Death) Databases (commercial insurance/Medicare Advantage [COM/MA]; 01 January 2014-31 July 2019) and Medicare Fee-for-Service (Medicare-FFS; 01 January 2014-31 December 2017).

RESULTS

Previous real-world studies identified mCSPC primarily based on metastasis diagnosis codes, and mCRPC based on mCRPC-specific drugs. Using the current study's algorithms, 7034 COM/MA and 19,981 Medicare-FFS patients were identified as having mCSPC, and 2578 COM/MA and 11,554 Medicare-FFS as having mCRPC. Most mCSPC patients were identified based on evidence of being hormone/castration-naive. Patients were identified as having mCRPC most commonly based on rising PSA (COM/MA), or at the metastasis diagnosis date if it occurred after castration (Medicare-FFS). Among patients with mCSPC, 14-17% had evidence of progression to castration resistance during a median 1-year follow-up period, mostly based on use of mCRPC-specific drugs.

CONCLUSIONS

Comprehensive algorithms based on claims and laboratory data were developed to identify and distinguish patients with mCSPC and mCRPC. This will facilitate appropriate identification of mCSPC and mCRPC patients based on health claims data and better understanding of patient unmet needs in real-world settings.