Current management of castrate-resistant prostate cancer

Metastatic castration resistant prostate cancer patients' experience with Radium-223 treatment in Japan

Aim: We aimed to determine Japanese metastatic castration resistant prostate cancer (CRPC) patients' Ra-223 treatment experience. Patients & methods: Patients answered the Cancer Therapy Satisfaction Questionnaire (CTSQ domains: Satisfaction with Therapy [SWT], Expectations of Therapy [ET], Feelings about Side Effects [FSE]), the Memorial Anxiety Scale for Prostate Cancer (MAX-PC) and the FACT-Bone Pain (FACT-BP) Questionnaire at baseline, during (vists 3 and 5) and after treatment (end of observation; EOO). Results: Data from 72 patients were included. Baseline median CTSQ scores SWT: 66.1 (IQR19.7), ET: 75.0 (IQR45), and FSE 68.8 (IQR 34.4) were unchanged during vists 3 and 5, but the SWT (-3.57 [IQR17.9]) and ET (-5.0 [IQR30]) decreased while FSE was unchanged (0.0 [IQR31.25]) at EOO. The median MAX-PC (18.0 [IQR 49]) score was unchanged (0.0, IQR 6) while the median FACT BP (54.0 [IQR13]) score decreased by -1.0 (IQR 8) at EOO. Conclusion: Japanese metastatic castration resistant prostate cancer patients' experience is stable during Ra-223 treatment.

Adverse events and costs among non-metastatic castration-resistant prostate cancer patients

BACKGROUND

Limited real-world evidence exists on the economic burden of adverse events (AEs) to the healthcare system among patients with non-metastatic castration-resistant prostate cancer (nmCRPC) treated with second-generation androgen receptor antagonists (ARAs). Current data is needed to understand real-world clinical event rates among ARAs and the cost of these events.

OBJECTIVES

Describe the incidence of non-central nervous system (CNS)-related AEs and CNS-related AEs among nmCRPC patients treated in the United States with second-generation ARAs (apalutamide and enzalutamide) and evaluate healthcare resource utilization (HCRU) and costs for these patients.

METHODS AND STUDY DESIGN

This was a retrospective observational cohort study using claims data from Optum Clinformatics Data Mart to identify adult males with prostate cancer, castration, no metastases, and >1 claim for apalutamide or enzalutamide. The study was conducted from January 2017 to March 2020, with a patient index identification period from January 2018 to December 2019. AEs were classified as CNS-related or non-CNS-related.

RESULTS

Of 605 patients (156 apalutamide and 449 enzalutamide), most were ≥65 years (94%) and had ≥1 non-CNS-related AE (55%). Many had ≥1 CNS-related AE (32%). Pain (12%) and arthralgia (11%) were the most frequently reported non-CNS-related AEs. Fatigue/asthenia (14%) and dizziness (7%) were the most frequently reported CNS-related AEs. Among patients with versus without non-CNS-related AEs, 34% versus 8% had emergency room (ER) events, and 25% versus 2% had inpatient events. Among patients with versus without CNS-related AEs, 41% versus 14% had ER events, and 38% versus 4% had inpatient events. Adjusted per-patient per-year cost (in 2020 USD) differences were significant between patients with and without non-CNS-related AEs ($30,765, p = 0.0018) and between patients with and without CNS-related AEs ($40,689, p = 0.0017).

CONCLUSION

There is significant HCRU and cost burden among nmCRPC patients treated with ARAs developing AEs, highlighting the need for treatments with improved tolerability. Additional studies are warranted to include recently approved agents.

Treatment Patterns, Clinical Outcomes, Health Care Resource Utilization and Costs in Older Patients With Metastatic Castration-Resistant Prostate Cancer in the United States: An Analysis of SEER-Medicare Data

BACKGROUND

Prostate cancer (PC) is more likely to develop in men ≥65 years old than in those <65 years old. This study aimed to generate real-world evidence on treatment patterns, clinical outcomes, health care resource utilization (HCRU), and costs among older patients with metastatic castration-resistant PC (mCRPC).

MATERIALS AND METHODS

A claims algorithm based on treatments expected for mCRPC was used to identify men ≥65 years old with mCRPC in the SEER-Medicare data between 2007 and 2019. The index date was defined as the date of the start of first-line therapy (1L). Treatment patterns and all-cause and PC-specific HCRU and costs were measured in the 12 months preindex period and the postindex follow-up period. Time to next treatment or death (TNTD) and overall survival (OS) were assessed in the follow-up period.

RESULTS

A total of 4758 patients met the eligibility criteria and received 1L treatment. Among these 1L patients, 57.4% subsequently received second-line (2L) treatment; among patients receiving 2L treatment, 49.3% subsequently received third-line (3L) treatment. Abiraterone, enzalutamide, and docetaxel were most common regimens in 1L (41.9%, 22.0%, 22.0%, respectively), 2L (33.3%, 32.7%, 13.6%, respectively), and 3L (17.9%, 25.1%, 22.3%, respectively). On average, patients had 1.2 inpatient admissions, 1.1 emergency room visits, and 27.6 outpatient visits per year during follow-up. The mean total all-cause and PC-related costs during the follow-up period were $111,060 and $99,540 per-patient-per-year, respectively. Median TNTD was 9.3, 6.5, and 5.7 months for 1L, 2L, and 3L, respectively. Median OS from the start of 1L treatment for mCRPC was 21.5 months.

DISCUSSION

Among older patients with mCRPC, high attrition from 1L to subsequent lines of therapy was observed. Median TNTD was <1 year and median OS was <2 years. These results highlight a need to introduce more effective mCRPC therapies in 1L to improve clinical outcomes for older patients.

Prostate cancer and bone: clinical presentation and molecular mechanisms

Prostate cancer (PCa) is an increasingly prevalent health problem in the developed world. Effective treatment options exist for localized PCa, but metastatic PCa has fewer treatment options and shorter patient survival. PCa and bone health are strongly entwined, as PCa commonly metastasizes to the skeleton. Since androgen receptor signaling drives PCa growth, androgen-deprivation therapy whose sequelae reduce bone strength constitutes the foundation of advanced PCa treatment. The homeostatic process of bone remodeling - produced by concerted actions of bone-building osteoblasts, bone-resorbing osteoclasts, and regulatory osteocytes - may also be subverted by PCa to promote metastatic growth. Mechanisms driving skeletal development and homeostasis, such as regional hypoxia or matrix-embedded growth factors, may be subjugated by bone metastatic PCa. In this way, the biology that sustains bone is integrated into adaptive mechanisms for the growth and survival of PCa in bone. Skeletally metastatic PCa is difficult to investigate due to the entwined nature of bone biology and cancer biology. Herein, we survey PCa from origin, presentation, and clinical treatment to bone composition and structure and molecular mediators of PCa metastasis to bone. Our intent is to quickly yet effectively reduce barriers to team science across multiple disciplines that focuses on PCa and metastatic bone disease. We also introduce concepts of tissue engineering as a novel perspective to model, capture, and study complex cancer-microenvironment interactions.

PTEN loss is not a determinant of time to castration-resistance following androgen-deprivation therapy in prostate cancer: a study from Jordan

Androgen deprivation therapy (ADT) remains the principal treatment of advanced prostate cancer. However, most patients eventually experience treatment failure, resulting in castrate-resistant prostate cancer (CRPC). Loss of the tumor suppressor gene phosphatase and tensin homolog (PTEN) has been linked to poor survival in prostate cancer. We have recently shown that PTEN loss is evident in approximately 60% of prostate cancer cases in Jordan. However, the correlation between PTEN loss and response to ADT remains unclear. This study aimed to determine the relationship between PTEN loss and time to CRPC in Jordan. We conducted a retrospective analysis of confirmed CRPC cases at our institution from 2005 to 2019 (N=104). PTEN expression was assessed using immunohistochemistry. Time to CRPC was calculated from the initiation of ADT to the confirmed diagnosis of CRPC. Combination/sequential ADT was defined as the use of two or more classes of ADT concomitantly or switching from one class to another. We found that PTEN loss was evident in 60.6% of CRPC. Mean time to CRPC was not different between patients with PTEN loss (24.8 months) and those with intact PTEN (24.2 months; p=0.9). However, patients receiving combination/sequential ADT had a significantly delayed onset of CRPC compared to patients on monotherapy ADT (log-rank Mantel-Cox p=0.000). In conclusion, PTEN loss is not a major determinant of time to CRPC in Jordan. The use of combination/sequential ADT procures a significant therapeutic advantage over monotherapy regimens, delaying the onset of CRPC.

Disability weights for castration-resistant prostate cancer: an empirical investigation

Introduction

Health state valuation and diagnostic-therapeutic pathways at the junction between non-metastatic and metastatic castration-resistant prostate cancer (CRPC) are not well documented. We aimed at: (i) estimating the disability weights (DWs) for health states across a continuum of disease from asymptomatic non-metastatic (nmCRPC) to symptomatic metastatic state (mCRPC); (ii) mapping the diagnostic-therapeutic pathway of nmCRPC in Italy.

Methods

Structured qualitative interviews were performed with clinical experts to gather information on nmCRPC clinical pathway. An online survey was administered to clinical experts to estimate DWs for four CRPC health states defined from interviews and literature review (i.e., nmCRPC, asymptomatic mCRPC, symptomatic mCRPC, mCRPC in progression during or after chemotherapy). Clinicians' preferences for health states were elicited using the Person-Trade-Off (PTO) and Visual Analogue Scale (VAS) methods. DWs associated with each health state, from 0 (best imaginable health state) and 1 (worst imaginable health state), were estimated.

Results

We found that the management of nmCRPC is heterogeneous across Italian regions and hospitals, especially with respect to diagnostic imaging techniques. DWs for PTO ranged from 0.415 (95% confidence interval [CI] 0.208-0.623) in nmCRPC to 0.740 (95% CI 0.560-0.920) in mCRPC, in progression during or after chemotherapy. DWs for VAS ranged between 0.246 (95% CI 0.131-0.361) in nmCRPC to 0.689 (95% CI 0.583-0.795) in mCRPC, in progression during or after chemotherapy.

Conclusions

Estimated DWs suggest that delaying transition to a metastatic state might ease the disease burden at both patient and societal levels.

S-nitrosylation of CSF1 receptor increases the efficacy of CSF1R blockage against prostate cancer

Sustained oxidative stress in castration-resistant prostate cancer (CRPC) cells potentiates the overall tumor microenvironment (TME). Targeting the TME using colony-stimulating factor 1 receptor (CSF1R) inhibition is a promising therapy for CRPC. However, the therapeutic response to sustained CSF1R inhibition (CSF1Ri) is limited as a monotherapy. We hypothesized that one of the underlying causes for the reduced efficacy of CSF1Ri and increased oxidation in CRPC is the upregulation and uncoupling of endothelial nitric oxide synthase (NOS3). Here we show that in high-grade PCa human specimens, NOS3 abundance positively correlates with CSF1-CSF1R signaling and remains uncoupled. The uncoupling diminishes NOS3 generation of sufficient nitric oxide (NO) required for S-nitrosylation of CSF1R at specific cysteine sites (Cys 224, Cys 278, and Cys 830). Exogenous S-nitrosothiol administration (with S-nitrosoglutathione (GSNO)) induces S-nitrosylation of CSF1R and rescues the excess oxidation in tumor regions, in turn suppressing the tumor-promoting cytokines which are ineffectively suppressed by CSF1R blockade. Together these results suggest that NO administration could act as an effective combinatorial partner with CSF1R blockade against CRPC. In this context, we further show that exogenous NO treatment with GSNOR successfully augments the anti-tumor ability of CSF1Ri to effectively reduce the overall tumor burden, decreases the intratumoral percentage of anti-inflammatory macrophages, myeloid-derived progenitor cells and increases the percentage of pro-inflammatory macrophages, cytotoxic T lymphocytes, and effector T cells, respectively. Together, these findings support the concept that the NO-CSF1Ri combination has the potential to act as a therapeutic agent that restores control over TME, which in turn could improve the outcomes of PCa patients.

Therapeutic potential of inhibiting histone 3 lysine 27 demethylases: a review of the literature

Histone 3 lysine 27 (H3K27) demethylation constitutes an important epigenetic mechanism of gene activation. It is mediated by the Jumonji C domain-containing lysine demethylases KDM6A and KDM6B, both of which have been implicated in a wide myriad of diseases, including blood and solid tumours, autoimmune and inflammatory disorders, and infectious diseases. Here, we review and summarise the pre-clinical evidence, both in vitro and in vivo, in support of the therapeutic potential of inhibiting H3K27-targeting demethylases, with a focus on the small-molecule inhibitor GSK-J4. In malignancies, KDM6A/B inhibition possesses the ability to inhibit proliferation, induce apoptosis, promote differentiation, and heighten sensitivity to currently employed chemotherapeutics. KDM6A/B inhibition also comprises a potent anti-inflammatory approach in inflammatory and autoimmune disorders associated with inappropriately exuberant inflammatory and autoimmune responses, restoring immunological homeostasis to inflamed tissues. With respect to infectious diseases, KDM6A/B inhibition can suppress the growth of infectious pathogens and attenuate the immunopathology precipitated by these pathogens. The pre-clinical in vitro and in vivo data, summarised in this review, suggest that inhibiting H3K27 demethylases holds immense therapeutic potential in many diseases.

Novel forms of prostate cancer chemoresistance to successful androgen deprivation therapy demand new approaches: Rationale for targeting BET proteins

In patients with prostate cancer, the duration of remission after treatment with androgen deprivation therapies (ADTs) varies dramatically. Clinical experience has demonstrated difficulties in predicting individual risk for progression due to chemoresistance. Drug combinations that inhibit androgen biosynthesis (e.g., abiraterone acetate) and androgen signaling (e.g., enzalutamide or apalutamide) have proven so effective that new forms of ADT resistance are emerging. In particular, prostate cancers with a neuroendocrine transcriptional signature, which demonstrate greater plasticity, and potentially, increased predisposition to metastasize, are becoming more prevalent. Notably, these subtypes had in fact been relatively rare before the widespread success of novel ADT regimens. Therefore, better understanding of these resistance mechanisms and potential alternative treatments are necessary to improve progression-free survival for patients treated with ADT. Targeting the bromodomain and extra-terminal (BET) protein family, specifically BRD4, with newer investigational agents may represent one such option. Several families of chromatin modifiers appear to be involved in ADT resistance and targeting these pathways could also offer novel approaches. However, the limited transcriptional and genomic information on ADT resistance mechanisms, and a serious lack of patient diversity in clinical trials, demand profiling of a much broader clinical and demographic range of patients, before robust conclusions can be drawn and a clear direction established.

The Antileukemic and Anti-Prostatic Effect of Aeroplysinin-1 Is Mediated through ROS-Induced Apoptosis via NOX Activation and Inhibition of HIF-1a Activity

Aeroplysinin-1 is a brominated isoxazoline alkaloid that has exhibited a potent antitumor cell effect in previous reports. We evaluated the cytotoxicity of aeroplysinin-1 against leukemia and prostate cancer cells in vitro. This marine alkaloid inhibited the cell proliferation of leukemia Molt-4, K562 cells, and prostate cancer cells Du145 and PC-3 with IC₅₀ values of 0.12 ± 0.002, 0.54 ± 0.085, 0.58 ± 0.109 and 0.33 ± 0.042 µM, respectively, as shown by the MTT assay. Furthermore, in the non-malignant cells, CCD966SK and NR8383, its IC₅₀ values were 1.54 ± 0.138 and 6.77 ± 0.190 μM, respectively. In a cell-free system, the thermal shift assay and Western blot assay verified the binding affinity of aeroplysinin-1 to Hsp90 and Topo IIα, which inhibited their activity. Flow cytometry analysis showed that the cytotoxic effect of aeroplysinin-1 is mediated through mitochondria-dependent apoptosis induced by reactive oxygen species (ROS). ROS interrupted the cellular oxidative balance by activating NOX and inhibiting HIF-1α and HO-1 expression. Pretreatment with N-acetylcysteine (NAC) reduced Apl-1-induced mitochondria-dependent apoptosis and preserved the expression of NOX, HO-1, and HIF-1a. Our findings indicated that aeroplysinin-1 targeted leukemia and prostate cancer cells through multiple pathways, suggesting its potential application as an anti-leukemia and prostate cancer drug lead.

Regulation of p27 (Kip1) by Ubiquitin E3 Ligase RNF6

The cyclin-dependent kinase inhibitor p27 (Kip1) is an important regulator of the G1/S checkpoint. It is degraded by the SCF-SKP2 complex in late G1 thereby allowing cells to progress to the S phase. Here we investigated the role of the E3 ubiquitin ligase RNF6 (Ring Finger Protein 6) in cell cycle progression in prostate cancer cells. Our data demonstrate that RNF6 can promote cell cycle progression by reducing the levels of p27. Knockdown of RNF6 led to an increase in the stability of p27 and to the arrest of cells in the G1 phase. RNF6 interacted with p27 via its KIL domain and this interaction was found to be phosphorylation independent. RNF6 enhanced ubiquitination and subsequent degradation of p27 in the early G0/G1 phase of the cell cycle. Knockdown of RNF6 expression by short hairpin RNA led to inhibition of the CDK2/Cyclin E complex thereby reducing phosphorylation of Retinoblastoma protein (Rb) and to a subsequent decrease in cell cycle progression and proliferation. Our data suggest that RNF6 acts as a negative regulator for p27^kip1 leading to its proteasome-dependent degradation in the early G0/G1 phase of the cell cycle.

Real-world burden of adverse events for apalutamide- or enzalutamide-treated non-metastatic castration-resistant prostate cancer patients in the United States

Background

Second-generation androgen receptor inhibitors (ARIs) have been associated with adverse events (AEs) such as fatigue, falls, fractures, and rash in non-metastatic castration-resistant prostate cancer (nmCRPC) patients as identified in clinical trials. The objectives of this study were to describe the incidence and management of AEs in patients receiving apalutamide and enzalutamide.

Methods

This retrospective chart review study was conducted in nmCRPC-treating sites in the United States. Patients starting apalutamide or enzalutamide between February 1, 2018 and December 31, 2018 were included and any AEs they experienced were recorded. AEs, including those considered to be of special interest as defined in the pivotal clinical trials of the second-generation ARIs, were analyzed and grouped retrospectively in this study. Detailed chart data (patient demographics, clinical characteristics, treatment history, type of AE, outcomes, and resource utilization) were then collected for a randomly selected subset among patients with ≥1 AE to characterize AEs and their management. Descriptive results were summarized.

Results

Forty-three sites participated in the study. A total of 699 patients were included, of whom 525 (75.1%) experienced ≥1 AE. The most common AEs were fatigue/asthenia (34.3%), hot flush (13.9%), and arthralgia (13.6%). In the subset of 250 patients randomly selected from those who experienced ≥1 AE, patients were primarily White (72.0%), the mean age was 71 years, 86.0% had an Eastern Cooperative Oncology Group score of 0–1 at nmCRPC diagnosis, and the average prostate specific antigen (PSA) value at diagnosis was 23.2 ng/mL. PSA-doubling time < 10 months was chosen as reason to initiate treatment in 40% of patients. The median duration of follow-up was 1.1 years, with 14.4% of patients progressing to metastasis by end of study period. Grade 3–4 and Grade 5 AEs occurred in 14.4 and 0.4% of patients, respectively. Actions taken to manage AEs included AE-directed treatment (38.0%), ARI discontinuation (10.4%), dose reduction (7.6%), and AE-related hospitalization (4.8%).

Conclusions

This study highlights the burden of AEs among nmCRPC patients treated with apalutamide or enzalutamide, providing a relevant real-world benchmark as clinical trial evidence and the treatment landcape for nmCRPC continues to evolve.

Adipocyte-Cancer Cell Interactions in the Bone Microenvironment

When compared to adipocytes in other anatomical sites, the interaction of bone marrow resident adipocytes with the other cells in their microenvironment is less well understood. Bone marrow adipocytes originate from a resident, self-renewing population of multipotent bone marrow stromal cells which can also give rise to other lineages such as osteoblasts. The differentiation fate of these mesenchymal progenitors can be influenced to favour adipogenesis by several factors, including the administration of thiazolidinediones and increased age. Experimental data suggests that increases in bone marrow adipose tissue volume may make bone both more attractive to metastasis and conducive to cancer cell growth. Bone marrow adipocytes are known to secrete a variety of lipids, cytokines and bioactive signaling molecules known as adipokines, which have been implicated as mediators of the interaction between adipocytes and cancer cells. Recent studies have provided new insight into the impact of bone marrow adipose tissue volume expansion in regard to supporting and exacerbating the effects of bone metastasis from solid tumors, focusing on prostate, breast and lung cancer and blood cancers, focusing on multiple myeloma. In this mini-review, recent research developments pertaining to the role of factors which increase bone marrow adipose tissue volume, as well as the role of adipocyte secreted factors, in the progression of bone metastatic prostate and breast cancer are assessed. In particular, recent findings regarding the complex cross-talk between adipocytes and metastatic cells of both lung and prostate cancer are highlighted.

Role of extracellular vesicles secretion in paclitaxel resistance of prostate cancer cells

Aim: The development of chemotherapy resistance is the major obstacle in the treatment of advanced prostate cancer (PCa). Extracellular vesicles (EVs) secretion plays a significant role among different mechanisms contributing to chemoresistance. Hence, inhibition of EVs release may increase the efficacy of chemotherapeutic drugs against PCa. Methods: Paclitaxel (PTX) resistant PCa cells (PC3-R and DU145-R) were treated with GW4869, a known exosome biogenesis inhibitor. EVs were isolated from the conditioned media by ExoQuick-based precipitation method and characterized for concentration and size distribution by nanoparticle tracking analysis. The effect of GW4869 treatment on the survival and growth of PCa cells was assessed by MTT, and colony formation assays in vitro, and ectopic PC3-R xenografts in male athymic nude mice in vivo. The effect of other EV biogenesis inhibitors, imipramine and dimethyl amiloride (DMA), treatment was also analyzed on the survival of PC3-R cells. Results: GW4869 (10-20 µM) treatment of PTX resistant PCa cells significantly reduced the release of small EVs (50-100 nm size range) while increasing the release of larger EVs (> 150 nm in size), and inhibited their clonogenicity. Moreover, GW4869 (5-20 µM) treatment (24-72h) significantly inhibited the survival of PC3-R cells in a dose-dependent manner. We observed a similar growth inhibition with both imipramine (5-20 µg/mL) and DMA (5-20 µg/mL) treatment in PC3-R cells. Furthermore, GW4869 treatment (IP) in mice bearing PC3-R xenografts significantly reduced the tumor weight (65% reduction, P = 0.017) compared to the vehicle-treated control mice without causing any noticeable toxicity. Conclusion: Inhibiting the release of EVs could sensitize the resistant PCa cells to chemotherapy.

Melatonin and Prostate Cancer: Anti-tumor Roles and Therapeutic Application

Melatonin is an endogenous indoleamine that has been shown to inhibit tumor growth in laboratory models of prostate cancer. Prostate cancer risk has additionally been associated with exogenous factors that interfere with normal pineal secretory activity, including aging, poor sleep, and artificial light at night. Therefore, we aim to expand on the important epidemiological evidence, and to review how melatonin can impede prostate cancer. More specifically, we describe the currently known mechanisms of melatonin-mediated oncostasis in prostate cancer, including those that relate to the indolamine's ability to modulate metabolic activity, cell cycle progression and proliferation, androgen signaling, angiogenesis, metastasis, immunity and oxidative cell status, apoptosis, genomic stability, neuroendocrine differentiation, and the circadian rhythm. The outlined evidence underscores the need for clinical trials to determine the efficacy of supplemental, adjunct, and adjuvant melatonin therapy for the prevention and treatment of prostate cancer.

Long non-coding RNAs and their potential impact on diagnosis, prognosis, and therapy in prostate cancer: racial, ethnic, and geographical considerations

INTRODUCTION

Advances in high-throughput sequencing have greatly advanced our understanding of long non-coding RNAs (lncRNAs) in a relatively short period of time. This has expanded our knowledge of cancer, particularly how lncRNAs drive many important cancer phenotypes via their regulation of gene expression.

AREAS COVERED

Men of African descent are disproportionately affected by PC in terms of incidence, morbidity, and mortality. LncRNAs could serve as biomarkers to differentiate low-risk from high-risk diseases. Additionally, they may represent therapeutic targets for advanced and castrate-resistant cancer. We review current research surrounding lncRNAs and their association with PC. We discuss how lncRNAs can provide new insights and diagnostic biomarkers for African American men. Finally, we review advances in computational approaches that predict the regulatory effects of lncRNAs in cancer.

EXPERT OPINION

PC diagnostic biomarkers that offer high specificity and sensitivity are urgently needed. PC specific lncRNAs are compelling as diagnostic biomarkers owing to their high tissue and tumor specificity and presence in bodily fluids. Recent studies indicate that PCA3 clinical utility might be restricted to men of European descent. Further work is required to develop lncRNA biomarkers tailored for men of African descent.

Abscopal Effects in Metastatic Cancer: Is a Predictive Approach Possible to Improve Individual Outcomes?

Patients with metastatic cancers often require radiotherapy (RT) as a palliative therapy for cancer pain. RT can, however, also induce systemic antitumor effects outside of the irradiated field (abscopal effects) in various cancer entities. The occurrence of the abscopal effect is associated with a specific immunological activation in response to RT-induced cell death, which is mainly seen under concomitant immune checkpoint blockade. Even if the number of reported apscopal effects has increased since the introduction of immune checkpoint inhibition, its occurrence is still considered rare and unpredictable. The cases reported so far may nevertheless allow for identifying first biomarkers and clinical patterns. We here review biomarkers that may be helpful to predict the occurrence of abscopal effects and hence to optimize therapy for patients with metastatic cancers.

A qualitative research study in Japan investigating patients' experience with metastatic castration-resistant prostate cancer: from diagnosis to decision for Ra-223 treatment

Aim: This qualitative study aimed to reveal symptoms and impacts among bone metastatic castration-resistant prostate cancer (or mCRPC) Japanese patients, prior to Radium-223 (Ra-223) treatment. Materials & Methods: Twenty-three mCRPC patients designated to receive Ra-223 and three treating physicians (Ra-223 prescribers) in Japan, were interviewed. All interview data were assessed for concept frequency, themes and saturation. Results: Forty-five percent of the patients (mean age: 75.8 years) were symptomatic at the time of enrollment. Interviews with all patients revealed 47 mCRPC symptoms, including back pain and bone-specific pain, and 45 life impacts, including worry about disease progression and the impact on daily, physical activities. Conclusion: The symptoms and impacts of living with mCRPC and the associated burden of bone metastasis and skeletal-related symptoms are varied and are important considerations for treatment.

Natural Product-Based Studies for the Management of Castration-Resistant Prostate Cancer: Computational to Clinical Studies

Background: With prostate cancer being the fifth-greatest cause of cancer mortality in 2020, there is a dire need to expand the available treatment options. Castration-resistant prostate cancer (CRPC) progresses despite androgen depletion therapy. The mechanisms of resistance are yet to be fully discovered. However, it is hypothesized that androgens depletion enables androgen-independent cells to proliferate and recolonize the tumor. Objectives: Natural bioactive compounds from edible plants and herbal remedies might potentially address this need. This review compiles the available cheminformatics-based studies and the translational studies regarding the use of natural products to manage CRPC. Methods: PubMed and Google Scholar searches for preclinical studies were performed, while ClinicalTrials.gov and PubMed were searched for clinical updates. Studies that were not in English and not available as full text were excluded. The period of literature covered was from 1985 to the present. Results and Conclusion: Our analysis suggested that natural compounds exert beneficial effects due to their broad-spectrum molecular disease-associated targets. In vitro and in vivo studies revealed several bioactive compounds, including rutaecarpine, berberine, curcumin, other flavonoids, pentacyclic triterpenoids, and steroid-based phytochemicals. Molecular modeling tools, including machine and deep learning, have made the analysis more comprehensive. Preclinical and clinical studies on resveratrol, soy isoflavone, lycopene, quercetin, and gossypol have further validated the translational potential of the natural products in the management of prostate cancer.

Akt isoforms differentially provide for chemoresistance in prostate cancer

OBJECTIVE

Early prostate cancer micrometastatic foci undergo a mesenchymal to epithelial reverting transition, not only aiding seeding and colonization, but also rendering the tumor cells generally chemoresistant. We previously found that upregulated E-cadherin in the epithelial micrometastases activated canonical survival pathways, including PI3K-Akt, that protected the tumor cells from death; however, the extent of protection from blocking the pathway in its entirety was modest, because different isoforms may have alternately affected cell functioning. Here, we characterized Akt isoform expressions in primary and metastatic prostate cancers, as well as their individual contributions to chemoresistance.

METHODS

Akt isoforms and E-cadherin were manipulated with drugs, knocked down, and over expressed. Tumor cell killing was determined in vitro and in vivo. Overall survival was calculated from patient records and specimens.

RESULTS

Pan-Akt inhibition sensitized tumor cells to chemotherapy, and specific blockade of Akt1 or/and Akt2 caused cells to be more chemoresponsive. Overexpression of Akt3 induced apoptosis. A low dose of Akt1 or Akt2 inhibitor enabled standard chemotherapies to significantly eradicate metastatic prostate tumors in a mouse model, acting as chemosensitizers. In human specimens, we found Akt1 and Akt2 positively correlated, whereas Akt3 inversely correlated, with the overall survival of prostate cancer patients. Akt1high/Akt2high/Akt3low tumors had the worst outcomes.

CONCLUSIONS

E-cadherin-induced activation of Akt1/2 isoforms was the essential mechanism of chemoresistance, whereas Akt3 made cells more fragile. These findings emphasized the need to target Akt1/2, rather than pan-Akt, as a rational therapeutic approach.

Effects of low-dose bufalin combined with hydroxycamptothecin on human castration-resistant prostate cancer xenografts in nude mice

Prostate cancer is the most prevalent tumor found in men worldwide. Despite the efficiency of primary endocrine prostate cancer therapies, more efficient drugs are needed to tackle the most advanced and resistant forms of this condition. The present study investigated the antitumor effects of low-dose bufalin combined with hydroxycamptothecin on castration-resistant prostate cancer (CRPC) in mice, as well as the possible mechanisms of apoptosis induction. CRPC xenograft tumors were generated in mice and, subsequently, mice received appropriate doses of bufalin, hydroxycamptothecin or a combination of the two drugs. Tumors from each treatment group were removed, and the tumor volume, weight and inhibition rate of each group was determined. Hematoxylin and eosin staining was performed for pathological analysis and TUNEL staining was used to assess the level of apoptosis in the xenografts. Immunohistochemistry was used for the analysis of proliferating cell nuclear antigen expression and the expression of Bax, Bcl-XL, p53, programmed cell death 4 (PDCD4), phosphorylated (p)-AKT and glycogen synthase kinase (GSK)-3β was determined by western blotting. Treatment with bufalin significantly (P<0.05) reduced tumor volumes compared with the negative control group, reducing tumor volumes to lower levels when combined with hydroxycampothecin. The combination of bufalin (0.6 or 0.8 mg/kg) and hydroxycampothecin significantly (P<0.05) induced higher levels of cell apoptosis compared with the administration of bufalin or hydroxycampothecin alone. The combination of bufalin and hydroxycampothecin also increased the expression of apoptosis-related proteins Bax, p53, PDCD4 and GSK-3β, and decreased the expression of Bcl-XL and p-AKT compared with a single drug treatment. The present study suggested that the combination of bufalin and hydroxycampothecin improved the inhibitory effects of both drugs on CRPC tumors in vivo, potentially via the regulation of the PI3K/AKT/GSK-3β and p53-dependent apoptosis signaling pathways.

Suppressed PLIN3 frequently occurs in prostate cancer, promoting docetaxel resistance via intensified autophagy, an event reversed by chloroquine

Lipid metabolism reprogramming is one of the adaptive events that drive tumor development and survival, and may account for resistance to chemotherapeutic drugs. Perilipins are structural proteins associated with lipophagy and lipid droplet integrity, and their overexpression is associated with tumor aggressiveness. Here, we sought to explore the role of lipid droplet-related protein perilipin-3 (PLIN3) in prostate cancer (PCa) chemotherapy. We investigated the role of PLIN3 suppression in docetaxel cytotoxic activity in PCa cell lines. Additional effects of PLIN3 depletion on autophagy-related proteins and gene expression patterns, apoptotic potential, proliferation rate, and ATP levels were examined. Depletion of PLIN3 resulted in docetaxel resistance, accompanied by enhanced autophagic flux. We further assessed the synergistic effect of autophagy suppression with chloroquine on docetaxel cytotoxicity. Inhibition of autophagy with chloroquine reversed chemoresistance of stably transfected shPLIN3 PCa cell lines, with no effect on the parental ones. The shPLIN3 cell lines also exhibited reduced Caspase-9 related apoptosis initiation. Moreover, we assessed PLIN3 expression in a series of PCa tissue specimens, were complete or partial loss of PLIN3 expression was frequently noted in 70% of the evaluated specimens. Following PLIN3 silencing, PCa cells were characterized by impaired lipophagy and acquired an enhanced autophagic response upon docetaxel-induced cytotoxic stress. Such an adaptation leads to resistance to docetaxel, which could be reversed by the autophagy blocker chloroquine. Given the frequent loss of PLIN3 expression in PCa specimens, we suggest that combination of docetaxel with chloroquine may improve the efficacy of docetaxel treatment in PLIN3-deficient cancer patients.

Real-World Treatment Patterns and Overall Survival of Patients with Metastatic Castration-Resistant Prostate Cancer in the US Prior to PARP Inhibitors

Introduction

Therapeutic options for metastatic castration-resistant prostate cancer (mCRPC) patients are continuously advancing. We described mCRPC treatment patterns in the US from 2013 to 2019.

Methods

Patients with a confirmed mCRPC diagnosis and adenocarcinoma histology were included in the US Flatiron Health Electronic Health Record-derived de-identified database. Treatment patterns [including treatment per lines of therapies (LOTs), LOT sequences, and time on treatment] and overall survival (OS) have been described in mCRPC settings.

Results

Of 5213 patients (mean age: 72.6 years), 4374 (83.9%) were treated with ≥ 1 LOT post-mCRPC diagnosis (among those with ≥ 1 LOT, 55.3%, 29.5%, 14.7%, and 6.7% had ≥ 2, 3, 4, and 5 LOTs, respectively). In first line (1L), the main treatment class was next-generation hormonal agents (NHA; 62.5% of patients with ≥ 1 LOT), while the shortest and longest time on 1L were observed for chemotherapy (median 2.8 months) and NHA (median 5.1 months), respectively. The most common LOT sequences were NHA → NHA (29.4% of patients with ≥ 2 LOTs) and NHA → NHA → chemotherapy (16.7% of patients with ≥ 3 LOTs). In Kaplan–Meier analyses, the median OS was 19.4, 14.6, and 11.1 months post-1L, 2L, and 3L start, respectively. Patients who moved rapidly through LOTs had an increased risk of death.

Conclusions

NHA were widely used as 1L therapy in mCRPC patients from 2013 to 2019, but time on 1L NHA treatment was on average < 6 months. While NHA → NHA was the most observed 1L → 2L LOT sequence, a plethora of other LOT sequences were observed. OS was poor, highlighting an unmet need for life-prolonging treatments.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01823-6.

Piperlongumine inhibits migration and proliferation of castration-resistant prostate cancer cells via triggering persistent DNA damage

BACKGROUND

Metastatic castration-resistant prostate cancer (CRPC) is the leading cause of death among men diagnosed with prostate cancer. Piperlongumine (PL) is a novel potential anticancer agent that has been demonstrated to exhibit anticancer efficacy against prostate cancer cells. However, the effects of PL on DNA damage and repair against CRPC have remained unclear. The aim of this study was to further explore the anticancer activity and mechanisms of action of PL against CRPC in terms of DNA damage and repair processes.

METHODS

The effect of PL on CRPC was evaluated by MTT assay, long-term cell proliferation, reactive oxygen species assay, western blot assay, flow cytometry assay (annexin V/PI staining), β-gal staining assay and DAPI staining assay. The capacity of PL to inhibit the invasion and migration of CRPC cells was assessed by scratch-wound assay, cell adhesion assay, transwell assay and immunofluorescence (IF) assay. The effect of PL on DNA damage and repair was determined via IF assay and comet assay.

RESULTS

The results showed that PL exhibited stronger anticancer activity against CRPC compared to that of taxol, cisplatin (DDP), doxorubicin (Dox), or 5-Fluorouracil (5-FU), with fewer side effects in normal cells. Importantly, PL treatment significantly decreased cell adhesion to the extracellular matrix and inhibited the migration of CRPC cells through affecting the expression and distribution of focal adhesion kinase (FAK), leading to concentration-dependent inhibition of CRPC cell proliferation and concomitantly increased cell death. Moreover, PL treatment triggered persistent DNA damage and provoked strong DNA damage responses in CRPC cells.

CONCLUSION

Collectively, our findings demonstrate that PL potently inhibited proliferation, migration, and invasion of CRPC cells and that these potent anticancer effects were potentially achieved via triggering persistent DNA damage in CRPC cells.

Utility of radiomic zones for risk classification and clinical outcome predictions using supervised machine learning during simultaneous 11 C-choline PET/MRI acquisition in prostate cancer patients

PURPOSE

In most radiomic studies related to cancer research, the traditional tumor-centric view has predominated. In this retrospective study, we go beyond the single-tumor region and investigate the utility of proposed radiomic zones for risk classification and clinical outcome predictions using radiomic features extracted from ¹¹ C-choline positron emission tomography (PET) imaging and supervised machine learning in prostate tumors.

MATERIALS AND METHODS

Seventy-seven prostate tumors were selected and delineated. The prostate organ was divided into three radiomic zones, with zone-1 being the metabolic tumor zone, zone-2 the proximal peripheral tumor zone, and zone-3 the extended peripheral tumor zone. LIFEx was used for PET-radiomic feature extraction. Risk groups were created using Gleason scores (GS), prostate-specific antigen (PSA) levels, clinical TNM staging, and progression-free survival (PFS). Random forest (RF) and AdaBoost advanced machine learning algorithms were used for supervised machine learning. Accuracy, positive predictive value, area under the receiver operating characteristic curve (AreaROC), and other metrics were calculated for comparisons of predictive performance between zones.

RESULTS

For the GS risk classification group, the accuracies of risk classification predictions were 71%, 71%, and 67% using RF and 65%, 64%, and 63% using AdaBoost for zones -1, -2, and -3, respectively. For the PSA group, the accuracies of risk classification predictions were 74%, 65%, and 64% using RF and 76%, 66%, and 67% using AdaBoost for zones -1, -2, and -3, respectively. For the TNM group, the accuracies of risk classification predictions were 68%, 76%, and 78% using RF and 66%, 75%, and 80% using AdaBoost for zones -1, -2, and -3, respectively. For the PFS group, the accuracies of clinical outcome predictions were 77%, 75%, and 83% using RF and 77%, 74%, and 83% using AdaBoost in zones -1, -2, and -3, respectively.

CONCLUSIONS

We proposed three radiomic zones with different standard uptake value characteristics and created four risk groups of prostate cancer patients for testing this idea. We showed that these radiomic zones have different predicting strengths in classifying risk groups and might allow us to identify a radiomic zone with higher accuracy for patient outcome prediction.

Treatment and trials in non-metastatic castration-resistant prostate cancer

Metastatic prostate cancer is associated with considerable morbidity and mortality. Standard treatment for non-metastatic prostate cancer, to prevent metastatic progression, is androgen deprivation therapy (ADT); however, many patients will eventually develop castration-resistant prostate cancer (CRPC), which can prove challenging to treat. Between the stages of non-metastatic androgen-sensitive disease and metastatic CRPC is an intermediate disease state that has been termed non-metastatic CRPC (nmCRPC), which is a heterogeneous, man-made disease stage that occurs after a patient who has no radiological evidence of metastasis shows evidence of cancer progression even after ADT. Awareness of nmCRPC has risen owing to an increased use of ADT and its eventual failure. Men with nmCRPC are at a high risk of progression to mCRPC, with historically few options to halt this process. However, in the past two decades, multiple therapies have been investigated for the treatment of nmCRPC, including endothelin receptor antagonists and bone-targeted therapies, but none has changed the standard of care. In the past decade, the efficacy of androgen receptor pathway-targeting modalities has been investigated. Three novel nonsteroidal antiandrogen agents for treating high-risk nmCRPC have been investigated; the PROSPER, SPARTAN and ARAMIS trials were phase III, randomized, placebo-controlled clinical trials that investigated the efficacy and safety of enzalutamide, apalutamide and darolutamide, respectively. All three therapeutics showed statistically significant improvements in metastasis-free survival, progression to antineoplastic therapy was lengthened and at final analysis, overall survival was significantly improved. The comparative efficacy and safety of all three agents has not yet been investigated in a comprehensive clinical trial, but approval of these medications by the FDA and other regulatory agencies means that providers now have three effective therapeutic options to augment ADT for patients with nmCRPC.

Clinical outcomes, management, and treatment patterns in patients with metastatic castration-resistant prostate cancer treated with radium-223 in community compared to academic settings

BACKGROUND

The most common site of disease in metastatic castration-resistant prostate cancer (mCRPC) is the bone. The ALSYMPCA study demonstrated that radium-223 significantly improved overall survival (OS) in mCRPC patients with symptomatic bone metastases and without visceral metastases. However, administration requires a multidisciplinary approach and an infrastructure that supports coordination of care, which may differ by practice site. We aimed to evaluate practice patterns and treatment outcomes in patients with mCRPC treated at a community practice (CP) compared with those treated at an academic center (AC).

METHODS

This retrospective review included 200 adult mCRPC patients receiving radium-223 between January 2014 and June 2017. The primary endpoint, OS, was estimated from the date of radium-223 initiation. Secondary outcomes included a comparison of baseline characteristics, reasons for initiation and discontinuation of radium-223, and treatment sequencing. A subset analysis of OS based on the number of radium-223 doses and on sequencing of radium-223 either before or after chemotherapy was also conducted.

RESULTS

Most patients were treated at a CP (57%). Patients treated at CP sites were significantly older (74.9 vs. 71.9 years; p = .031) and had more comorbidities (Klabunde score 1.1 vs. 0.7; p = .020) than those in an AC but initiated treatment within a shorter period of time from diagnosis of mCRPC (1.3 vs. 1.9 years; p < .001) and received a greater mean number of radium-223 doses (5.4 vs. 4.8; p = .001). There were no observed differences in OS between CPs versus ACs (21.6 vs. 20.7 months; p = .306). Overall, patients who received 5-6 doses versus 1-4 doses of radium-223 had a longer median OS (23.3 vs. 6.4 months; p < .001). The most common reason for discontinuation in patients who did not complete treatment was disease progression. Overall, 43% of patients received radium-223 monotherapy and 57% concurrently with other agents.

CONCLUSIONS

Most patients received radium-223 concurrently with abiraterone acetate or enzalutamide and were able to complete 5-6 doses of radium-223. Despite differences in the populations and treatment patterns, no survival differences between patients treated in ACs versus CPs were observed. Additional real-world data are needed to validate these findings.

Zhoushi Qiling decoction induces apoptosis of human prostate cancer cells via miR-143/Bcl-2 axis

A number of traditional Chinese medicines (TCMs) are widely used in prostate cancer treatment in China. The aim of this study was to test the efficacy of a TCM, Zhoushi Qiling Decoction (ZQD), in combination with androgen deprivation therapy (ADT) and explore its underlying mechanism. A total of 151 patients were recruited to receive ADT treatment or ADT+ZQD treatment. The survival of patients who received ADT+ZQD treatment was significantly higher than those who received ADT therapy only. DU145 prostate cancer cells were treated with ZQD (50 mg/mL) for 24 h in vitro and expression levels of an array of miRNAs were examined. Our results suggested that miR-143 demonstrated prominent upregulation in DU145 cells after treatment with ZQD. In patient serum samples, miR-143 expression was also significantly upregulated after ADT+ZQE treatment, which was however absent in patients treated with ADT only. In DU145 cells, ZQD treatment led to a dose-dependent increase in apoptosis, which could be reduced by anti-miR-143 treatment. There was a binding site between miR-143 and B cell CLL/lymphoma-2 (Bcl-2) and ZQD treatment reduced Bcl-2 expression. ZQD treatment led to increased caspase-3 and Bax expression. ZQD treatment could promote apoptosis of prostate cancer cells by promoting miR-143 upregulation, which could be a possible mechanism underlying the inhibitory effect of ZQD in prostate cancer in patient.

Experience with using fosfestrol for treating metastatic castrate-resistant prostate cancer in resource-limited setting

Background: Fosfestrol is a low-cost estrogen analog that is useful in the management of metastatic prostate cancer in resource-challenged settings. It acts by altering the pituitary axis, adrenal secretion, and 5-alpha reductase activity. Patients and Methods: The outcomes of metastatic castration-resistant prostate cancer patients treated with fosfestrol in our center between June 2012 and December 2015 were analyzed retrospectively. Fosfestrol was given orally at a dose of 120 mg thrice daily. Event was defined as the discontinuation of fosfestrol due to tumor progression or drug toxicity or death due to any cause. The event-free survival (EFS) and overall survival (OS) were calculated by the Kaplan–Meier method. Results: The analysis included 47 patients with a median age of 65 years. Initial Gleason score was available for 41 of 47 patients, of which 17% (7), 39% (16), and 44% (18) were low risk, intermediate risk, and high risk, respectively. The most common site of metastasis was bone (98%). Of 47 patients, 32 (68%) received fosfestrol as the second line of treatment after progression on complete androgen blockade, 14/47 (30%) received it as the third line, and 1/47 received it as the fourth line of treatment. The median prostate-specific antigen (PSA) value at the start of fosfestrol and the nadir PSA value were 43.7 ng/ml and 13.1 ng/ml, respectively. Ninety-one percent (n = 43) of patients had not been previously treated with chemotherapy (docetaxel). Response of PSA of >50% was observed in 55% (n = 26) of patients. The median EFS and median OS after the start of fosfestrol were 6.8 and 14.7 months, respectively, with a median follow-up of 10.9 months. Only two patients developed Grade 3 toxicity, both of whom had diarrhea. Conclusions: In resource-challenged settings, oral fosfestrol is an effective, cheap, and safe option for the management of metastatic prostate cancer progressing after first-line complete androgen blockade.

SETDB1 in cancer: overexpression and its therapeutic implications

SET Domain Bifurcated Histone Lysine Methyltransferase 1 (SETDB1, ESET, KMT1E) is a H3K9 methyltransferase involved in gene silencing. In recent years, SETDB1 has been implicated as an oncogene in various cancers, highlighting a critical need to better understand the mechanisms underlying SETDB1 amplification, overexpression, and activation. In the following review, we first examine the history of SETDB1, starting from its discovery in 1999 and ending with recent findings. We follow with an outline of the structure and subcellular location of SETDB1, as well as potential mechanisms for regulation of its nuclear transport. Subsequently, we introduce SETDB1's various functions, including its roles in promyelocytic leukemia nuclear body (PML-NB) formation, the methylation and activation of Akt, the silencing of the androgen receptor (AR) gene, retroelement silencing, the inhibition of tumor suppressor p53, and its role in promoting intestinal differentiation and survival. The Cancer Cell Line Encyclopedia (CCLE) screened SETDB1 dependency in 796 cancer cell lines, identifying SETDB1 as a common essential gene in 531 of them, demonstrating that SETDB1 expression is critical for the survival of the majority of cancers. Therefore, we provide a detailed review of the oncogenic effects of SETDB1 overexpression in breast cancer, non-small cell lung cancer, prostate cancer, colorectal cancer, acute myeloid leukemia, glioma, melanoma, pancreatic ductal adenocarcinoma, liver cancer, nasopharyngeal carcinoma, gastric carcinoma, and endometrial cancer. Accordingly, we review several methods that have been used to target SETDB1, such as using Mithramycin A, Mithralog EC-8042, 3'-deazaneplanocin A (DZNep), and paclitaxel. Finally, we conclude by highlighting remaining gaps in knowledge and challenges surrounding SETDB1. Ultimately, our review captures the wide scope of findings on SETDB1's history, function, its implications in cancer, and provides suggestions for future research in the field.

1α,25-Dihydroxyvitamin D3 synergistically enhances anticancer effects of ginsenoside Rh2 in human prostate cancer cells

1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃, commonly known as calcitriol), the most active metabolite of vitamin D₃, and ginsenoside Rh2 can regulate cellular differentiation and proliferation proteins. The purpose of the present study was to assess the effect of 1,25(OH)₂D₃ on the anticancer activities of Rh2 in human prostate cancer cells such as androgen-dependent LNCaP and androgen-independent C4-2 in vitro. The effects of treatment with 1,25(OH)₂D₃ or Rh2, either alone or in combination, on prostate cancer cells were evaluated through tetrazolium-based cell viability assay, BrdU cell proliferation rate estimation assay, and Western blot protein expression analyses of nuclear receptors (androgen receptor and vitamin D receptors) and apoptotic proteins (Bcl-2, Bax, and Caspase 3). The Combination Indices (CI) and Dose Reduction Indices (DRI) of 1,25(OH)₂D₃ and Rh2 were calculated to determine synergistic anticancer activity using Calcusyn software (Biosoft, Cambridge, UK). The cell viability assay data indicate that Rh2 treatment alone inhibited cell viability in a concentration-dependent manner and the addition of 10 nM 1,25(OH)₂D₃ to Rh2 significantly enhanced its ability to reduce cell viability up to 80 % in both the cell lines. Similarly, addition of 10 nM 1,25(OH)₂D₃ to Rh2 significantly lowered its IC₅₀ values for cell proliferation from the range of 32-65 μM to 14-8 μM in LNCaP and C4-2 cells. In addition, protein expression analyses indicated that the combined treatment with Rh2 and 1,25(OH)₂D₃ led to greater downregulation of androgen receptor expression compared to single agent exposure. Similarly, the presence of 1,25(OH)₂D₃ synergistically increased the pro-apoptotic actions of Rh2 in both the cell lines. Overall, 1,25(OH)₂D₃ augments the Rh2-mediated anticancer effects through stimulating apoptosis and reduced cell proliferation which suggests that synergism of this combination may lead to potential lower need of the active vitamin D₃ and limited toxicity from it.

Quercetin and Its Nano-Scale Delivery Systems in Prostate Cancer Therapy: Paving the Way for Cancer Elimination and Reversing Chemoresistance

Prostate cancer is the second most leading and prevalent malignancy around the world, following lung cancer. Prostate cancer is characterized by the uncontrolled growth of cells in the prostate gland. Prostate cancer morbidity and mortality have grown drastically, and intensive prostate cancer care is unlikely to produce adequate outcomes. The synthetic drugs for the treatment of prostate cancer in clinical practice face several challenges. Quercetin is a natural flavonoid found in fruits and vegetables. Apart from its beneficial effects, its plays a key role as an anti-cancer agent. Quercetin has shown anticancer potential, both alone and in combination. Therefore, the current study was designed to collect information from the literature regarding its therapeutic significance in the treatment of prostate cancer. Studies performed both in vitro and in vivo have confirmed that quercetin effectively prevents prostate cancer through different underlying mechanisms. Promising findings have also been achieved in clinical trials regarding the pharmacokinetics and human applications of quercetin. In the meantime, epidemiological studies have shown a negative correlation between the consumption of quercetin and the incidence of prostate cancer, and have indicated a chemopreventive effect of quercetin on prostate cancer in animal models. The major issues associated with quercetin are its low bioavailability and rapid metabolism, and these require priority attention. Chemoresistance is another main negative feature concerning prostate cancer treatment. This review highlights the chemotherapeutic effect, chemo preventive effect, and chemoresistance elimination potential of quercetin in prostate cancer. The underlying mechanisms for elimination of prostate cancer and eradication of resistance, either alone or in combination with other agents, are also discussed. In addition, the nanoscale delivery of quercetin is underpinned along with possible directions for future study.

The discovery of novel sanjuanolide derivatives as chemotherapeutic agents targeting castration-resistant prostate cancer

There remains a critical need for more effective therapies for the treatment of castration-resistant prostate cancer (CRPC), which is the leading cause of death in patients with prostate cancer. In this study, a series of sanjuanolide derivatives were designed, synthesized and evaluated as potential anti-CRPC agents. Most of the compounds had excellent selectivity for CRPC cells with IC₅₀ values < 20 µM. Moreover, minimal side effects on human normal hepatic MIHA cells and normal prostatic stromal myofibroblast WPMY-1 cells were observed, with IC₅₀ > 100 µM. The representative compound S07 slowed down the proliferative rate of CRPC cells, promoted cell apoptosis and caused G2/M phase accumulation, as well as G1/G0 phase reduction. Further mechanistic studies showed that S07 treatment triggered intense DNA damage and provoked strong DNA damage response in a dose-dependent manner. These findings suggested that sanjuanolide derivatives, especially S07, selectively induced CRPC cell death by triggering intense DNA damage and DNA damage response.

Current advances of targeting epigenetic modifications in neuroendocrine prostate cancer

Neuroendocrine prostate cancer (NEPC) is the most lethal malignancy of prostate cancer (PCa). Treatment with next-generation androgen receptor (AR) pathway inhibitors (ARPIs) has successfully extended patients' lifespan. However, with the emergence of drug resistance, PCa tumors increasingly adapt to potent ARPI therapies by transitioning to alternative cellular lineage. Such therapy-induced drug resistance is largely driven from the cellular plasticity of PCa cells to alter their phenotypes of AR independence for cell growth and survival. Some of the resistant PCa cells undergo cellular reprogramming to form neuroendocrine phenotypes. Recent evidences suggest that this cellular reprogramming or the lineage plasticity is driven by dysregulation of the epigenome and transcriptional networks. Aberrant DNA methylation and altered expression of epigenetic modifiers, such as enhancer of zeste-homolog 2, transcription factors, histone demethylases, are hallmarks of NEPC. In this review, we discuss the nature of the epigenetic and transcriptional landscapes of PCa cells which lose their AR independence and transition to the neuroendocrine lineage. We also discuss how oncogenic signaling and metabolic reprogramming fuel epigenetic and transcriptional alterations. In addition, the current state of epigenetic therapies for NEPC is addressed.

Non-Coding RNAs Set a New Phenotypic Frontier in Prostate Cancer Metastasis and Resistance

Prostate cancer (PCa) mortality remains a significant public health problem, as advanced disease has poor survivability due to the development of resistance in response to both standard and novel therapeutic interventions. Therapeutic resistance is a multifaceted problem involving the interplay of a number of biological mechanisms including genetic, signaling, and phenotypic alterations, compounded by the contributions of a tumor microenvironment that supports tumor growth, invasiveness, and metastasis. The androgen receptor (AR) is a primary regulator of prostate cell growth, response and maintenance, and the target of most standard PCa therapies designed to inhibit AR from interacting with androgens, its native ligands. As such, AR remains the main driver of therapeutic response in patients with metastatic castration-resistant prostate cancer (mCRPC). While androgen deprivation therapy (ADT), in combination with microtubule-targeting taxane chemotherapy, offers survival benefits in patients with mCRPC, therapeutic resistance invariably develops, leading to lethal disease. Understanding the mechanisms underlying resistance is critical to improving therapeutic outcomes and also to the development of biomarker signatures of predictive value. The interconversions between epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) navigate the prostate tumor therapeutic response, and provide a novel targeting platform in overcoming therapeutic resistance. Both microRNA (miRNA)- and long non-coding RNA (lncRNA)-mediated mechanisms have been associated with epigenetic changes in prostate cancer. This review discusses the current evidence-based knowledge of the role of the phenotypic transitions and novel molecular determinants (non-coding RNAs) as contributors to the emergence of therapeutic resistance and metastasis and their integrated predictive value in prostate cancer progression to advanced disease.

Prognostic implications of dual tracer PET/CT: PSMA ligand and [18F]FDG PET/CT in patients undergoing [177Lu]PSMA radioligand therapy

BACKGROUND

Prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) with ¹⁷⁷Lu-labeled PSMA ligands has achieved remarkable results in advanced disease stages of metastatic castration-resistant prostate cancer (mCRPC). However, not all patients benefit from this therapy. Different treatment responses could be explained by tumor heterogeneity triggered by progression and the number of prior treatments. PSMA-negative lesions can be missed on PSMA ligand PET/CT, which subsequently results in an underestimation of tumor burden. Conversely, high FDG uptake may also be an indicator of tumor aggressiveness and thus a poor prognostic marker for response to RLT and overall survival (OS). The aim of this analysis was to investigate the prognostic value of combined PSMA ligand PET/CT and [¹⁸F]fluorodeoxyglucose (FDG) PET/CT for outcome prediction in patients undergoing RLT.

MATERIALS AND METHODS

This bicentric analysis included 54 patients with mCRPC who underwent both FDG and PSMA ligand PET/CT imaging before RLT. In all patients, the pattern of PSMA ligand and FDG uptake was visually assessed. Patients with at least one FDG-positive, but PSMA-negative (FDG+/PSMA-) lesions were compared to patients without any FDG+/PSMA- lesions. A log-rank analysis was used to assess the difference in OS between subgroups.

RESULTS

Median OS was 11 ± 1.8 months (95% CI 7.4-14.6). A significantly lower OS (p < 0.001) was found in patients with at least one FDG+/PSMA- lesion at baseline PET/CTs (n = 18) with a median OS of 6.0 ± 0.5 months (95% CI: 5.0-7.0 months). In comparison, patients without any FDG+/PSMA- lesions (n = 36) had a median OS of 16.0 ± 2.5 months (95% CI: 11.2-20.8 months).

CONCLUSION

FDG+/PSMA- lesions are a negative predictor of overall survival in patients with mCRPC undergoing RLT. However, it remains to be determined if patients with FDG+/PSMA- lesions should be excluded from PSMA RLT.

Data-independent acquisition mass spectrometry (DIA-MS) for proteomic applications in oncology

Data-independent acquisition mass spectrometry (DIA-MS) is a next generation proteomic methodology that generates permanent digital proteome maps offering highly reproducible retrospective analysis of cellular and tissue specimens. The adoption of this technology has ushered a new wave of oncology studies across a wide range of applications including its use in molecular classification, oncogenic pathway analysis, drug and biomarker discovery and unravelling mechanisms of therapy response and resistance. In this review, we provide an overview of the experimental workflows commonly used in DIA-MS, including its current strengths and limitations versus conventional data-dependent acquisition mass spectrometry (DDA-MS). We further summarise a number of key studies to illustrate the power of this technology when applied to different facets of oncology. Finally we offer a perspective of the latest innovations in DIA-MS technology and machine learning-based algorithms necessary for driving the development of high-throughput, in-depth and reproducible proteomic assays that are compatible with clinical diagnostic workflows, which will ultimately enable the delivery of precision cancer medicine to achieve optimal patient outcomes.

Emerging role of tumor cell plasticity in modifying therapeutic response

Resistance to cancer therapy is a major barrier to cancer management. Conventional views have proposed that acquisition of resistance may result from genetic mutations. However, accumulating evidence implicates a key role of non-mutational resistance mechanisms underlying drug tolerance, the latter of which is the focus that will be discussed here. Such non-mutational processes are largely driven by tumor cell plasticity, which renders tumor cells insusceptible to the drug-targeted pathway, thereby facilitating the tumor cell survival and growth. The concept of tumor cell plasticity highlights the significance of re-activation of developmental programs that are closely correlated with epithelial-mesenchymal transition, acquisition properties of cancer stem cells, and trans-differentiation potential during drug exposure. From observations in various cancers, this concept provides an opportunity for investigating the nature of anticancer drug resistance. Over the years, our understanding of the emerging role of phenotype switching in modifying therapeutic response has considerably increased. This expanded knowledge of tumor cell plasticity contributes to developing novel therapeutic strategies or combination therapy regimens using available anticancer drugs, which are likely to improve patient outcomes in clinical practice.

Resetting the Bar of Castration Resistance - Understanding Androgen Dynamics in Therapy Resistance and Treatment Choice in Prostate Cancer

This review discusses impact of advancements in biologic understanding of prostate cancer (PCa) on definition and diagnosis of castration-resistant PCa (CRPC), predictive factors for progression to CRPC and treatment strategies. More sensitive assays confirm that bilateral orchiectomy reduces serum testosterone (T) closer to < 20 ng/dL than < 50 ng/dL, and evidence suggests that achieving T < 20 ng/dL improves outcomes and delays CRPC emergence. Regular T assessments will evaluate whether T is adequately suppressed in the setting of potential progression to CRPC, given that late dosing may result in T escape. More advanced imaging modalities and biomarker assays allow earlier detection of disease progression. Predictive factors for progression to CRPC include Gleason grade, extent of metastatic spread, germline hereditary factors such as gene mutations affecting androgen receptor amplification or DNA repair deficiency mutations, prostate-specific antigen kinetics, and biomarker analyses. Treatment options for CRPC have expanded beyond androgen deprivation therapy to include therapies that suppress T or inhibit its activity through varying mechanisms. Future directions include therapies with novel biological targets, drug combinations and personalized treatments. Advanced PCa management aims to delay progression to CRPC and prolong survival. With redefinition of castration and advancements in understanding of the biology of disease progression, diagnosis and treatment strategies should be re-evaluated. Definition of CRPC could be updated to reflect the T < 20 ng/dL requirement as this is a 'true' castrate level and may improve outcomes. It is important that androgen deprivation therapy as foundational therapy is continued even as new CRPC therapies are introduced.

Inhibition of Rac1 reverses enzalutamide resistance in castration-resistant prostate cancer

Enzalutamide, an androgen receptor inhibitor, has been clinically approved for the treatment of metastatic castration-resistant prostate cancer (CRPC) in the United States. However, patients only benefit from enzalutamide for a short period of time as resistance may develop. Therefore, it is vital to develop a novel strategy to overcome enzalutamide resistance. Ras-related C3 botulinum toxin substrate 1 (Rac1), which is commonly upregulated in human cancer types, has been recognized as a key molecular component in tumorigenesis, invasion and metastasis. However, the role of Rac1 in enzalutamide-resistance in prostate cancer (PCa) remains unknown. In the present study, Rac1 was demonstrated to be upregulated in enzalutamide-resistant PCa cells, and Rac1 knockdown inhibited enzalutamide-resistant cell proliferation and colony formation. Western blotting results indicated that enzalutamide treatment downregulated the expression levels of JNK and activated transcription factor 2, as well as enhanced the Bax/Bcl-2 ratio and induced cleavage of poly-ADP ribose polymerase. Moreover, knockdown of Rac1 in MR49F cells significantly inhibited cell migration and invasion via the downregulation of Snail and the upregulation of E-cadherin. The results of a nude mouse xenograft tumor model using 22RV1 cells demonstrated that enzalutamide inhibited tumor growth after Rac1 knockdown dramatically, compared to vehicle and single treatment groups. Therefore, the present study provided novel evidence that Rac1 may serve a crucial role in enzalutamide resistance, and that targeting Rac1 may be a potential approach for the treatment of CRPC.

Genistein Combined Polysaccharide (GCP) Can Inhibit Intracrine Androgen Synthesis in Prostate Cancer Cells

Our group and others have previously shown that genistein combined polysaccharide (GCP), an aglycone isoflavone-rich extract with high bioavailability and low toxicity, can inhibit prostate cancer (CaP) cell growth and survival as well as androgen receptor (AR) activity. We now elucidate the mechanism by which this may occur using LNCaP and PC-346C CaP cell lines; GCP can inhibit intracrine androgen synthesis in CaP cells. UPLC-MS/MS and qPCR analyses demonstrated that GCP can mediate a ~3-fold decrease in testosterone levels (p < 0.001) and cause decreased expression of intracrine androgen synthesis pathway enzymes (~2.5-fold decrease of 3βHSD (p < 0.001), 17βHSD (p < 0.001), CYP17A (p < 0.01), SRB1 (p < 0.0001), and StAR (p < 0.01)), respectively. Reverse-phase HPLC fractionation and bioassay identified three active GCP fractions. Subsequent NMR and LC-MS analysis of the fraction with the highest level of activity, fraction 40, identified genistein as the primary active component of GCP responsible for its anti-proliferative, pro-apoptotic, and anti-AR activity. GCP, fraction 40, and genistein all mediated at least a ~2-fold change in these biological activities relative to vehicle control (p < 0.001). Genistein caused similar decreases in the expression of 17βHSD and CYP17A (2.5-fold (p < 0.001) and 1.5-fold decrease (p < 0.01), respectively) compared to GCP, however it did not cause altered expression of the other intracrine androgen synthesis pathway enzymes; 3βHSD, SRB1, and StAR. Our combined data indicate that GCP and/or genistein may have clinical utility and that further pre-clinical studies are warranted.

Secretome analysis reveals upregulated granzyme B in human androgen-repressed prostate cancer cells with mesenchymal and invasive phenotype

Epithelial-mesenchymal transition (EMT) is a critical early step in cancer metastasis and a complex process that involves multiple factors. In this study, we used proteomics approaches to investigate the secreted proteins (secretome) of paired human androgen-repressed prostate cancer (ARCaP) cell lines, representing the epithelial (ARCaP-E) and mesenchymal (ARCaP-M) phenotypes. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses showed high levels of proteins involved in bone remodeling and extracellular matrix degradation in the ARCaP-M cells, consistent with the bone metastasis phenotype. Furthermore, LC-MS/MS showed a significantly higher level of the serine protease granzyme B (GZMB) in ARCaP-M conditioned media (CM) compared to that of ARCaP-E. Using quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) to detect mRNA and Western blot to detect protein expression, we further demonstrated that the GZMB gene was expressed by ARCaP-M and the protein was secreted extracellularly. ARCaP-M cells with GZMB gene knockdown using small interfering RNA (siRNA) have markedly reduced invasiveness as demonstrated by the Matrigel invasion assay in comparison with the scrambled siRNA negative control. This study reports that GZMB secretion by mesenchymal-like androgen-repressed human prostate cancer cells promotes invasion, suggesting a possible extracellular role for GZMB in addition to its classic role in immune cell-mediated cytotoxicity.

Not all prostate cancer is the same - patient perceptions: an Asia-Pacific region study

OBJECTIVE

To explore the perceptions of patients living with different stages of prostate cancer across the Asia-Pacific (APAC) region, as while extensive quantitative research has been undertaken into outcomes of treatments for prostate cancer, little in the way of qualitative research has been performed looking at subjective perceptions of patients in regard to their perceived deficits in the treatment of this condition and such research is particularly lacking in reference to the APAC region.

PATIENTS AND METHODS

Initial 45-min qualitative research interrogatory interviews were conducted with 12 patients from Australia, China and Japan to identify themes that were significant to patients in the management of prostate cancer. Thereafter, 150 patients with different stages of prostate cancer underwent 30-min online (Australia) or computer-assisted/personal interviews categorised on the five key themes identified, in order to more fully clarify the nature of patient perceptions of how their prostate cancer had been treated and the issues they felt could be more fully addressed in order to improve the management of this condition.

RESULTS

Interviews indicated common challenges and unmet needs among patients, including: (i) patients' feelings and emotional state change during their disease journey, (ii) patients lack of knowledge about prostate cancer and disease progression prior to diagnosis, (iii) patients felt shared decision-making was uncommon, (iv) patients have misperceptions about surgery, and (v) patients have unmet needs for greater information and support to manage their condition.

CONCLUSIONS

These patient perceptions of unmet needs in prostate cancer management stand in contrast to patient awareness of other common diseases such as heart failure and diabetes. Such unmet needs vary across disease stages and between different nationalities. Patients with prostate cancer in the APAC region appear to have gaps in knowledge about their disease and wish for greater information, support and public awareness about prostate cancer.

Pharmacotherapeutic strategies for castrate-resistant prostate cancer

INTRODUCTION

Metastatic castration-resistant prostate cancer (CRPC) is a potentially symptomatic disease with an eventual lethal outcome. Novel pharmaceutical agents are continuously studied with encouraging results in CRPC.

AREAS COVERED

In this perspective, the authors present established and promising pharmacotherapeutic strategies for the management of CRPC; both with and without metastases. Apart from the different treatment strategies, the authors present the relevant sequence of treatment through disease progression.

EXPERT OPINION

Usually, docetaxel should be considered the first line treatment in mCRPC. Abiraterone acetate (AA) plus prednisone or enzalutamide (ENZ) could be alternative treatments in chemotherapy naïve patients. Sipuleucel-T has been approved for the treatment of asymptomatic or minimally symptomatic mCRPC. Ra-223 has been approved for patients with mCRPC with symptomatic bone metastases (not visceral metastases). Cabazitaxel has been approved as the second line treatment to docetaxel in mCRPC. No differences in the overall survival has been observed between sequences starting with docetaxel versus AA/ENZ. Between AA-to-ENZ and ENZ-to-AA sequence, the AA-to-ENZ sequence appeared to be more favorable than the ENZ-to-AA regarding progression-free survival but not overall survival. Carbazitaxel seemed to retain its activity regardless of the treatment sequence. Of note, ENZ and apalutamide have been approved in non-metastatic CRPC.

Decreased biochemical progression in patients with castration-resistant prostate cancer using a novel mefenamic acid anti-inflammatory therapy: A randomized controlled trial

Prostate cancer (PCa) is the second most common non-dermatological cancer in men and is a growing public health problem. Castration-resistant disease (CRD) is the most advanced stage of the disease and is difficult to control. Patients with CRD may no longer accept conventional therapies as they are not in appropriate clinical conditions or they refuse to receive it. Given that inflammation is an essential component of CRD origin and progression, anti-inflammatory agents could be a therapeutic option with fenamates as one of the proposed choices. A prospective, randomized, double-blinded, 2-arm, parallel group, phase II-III clinical trial was performed involving 20 patients with CRD-PCa (with a prostate specific antigen level <100 ng/ml) that were undergoing androgen deprivation therapy (ADT) and did not accept any established treatment for that disease stage. In addition to ADT, 10 patients received placebo and 10 received mefenamic acid (500 mg orally every 12 h) for 6 months. The primary endpoint was the change in serum prostate-specific antigen (PSA) at 6 months. The PSA levels decreased significantly with mefenamic acid (an average 42% decrease), whereas there was an average 55% increase in the placebo group (P=0.024). In the patients treated with the placebo, 70% had biochemical disease progression (an increase of ≥25% in PSA levels), which did not occur in any of the patients treated with mefenamic acid (relative risk=0.12; 95% confidence interval, 0.01-0.85; P=0.033). There was a significant increase in quality of life (EQ-5D-5L score) and body mass index (BMI) with the experimental treatment. In conclusion, mefenamic acid administration decreased biochemical progression in patients with castration resistant PCa, improved their quality of life and increased their BMI. Future studies are required in order to strengthen the findings of the present clinical trial. Trial registration, Cuban Public Registry of Clinical Trials Database RPCEC00000248, August 2017.

177Lu-EB-PSMA Radioligand Therapy with Escalating Doses in Patients with Metastatic Castration-Resistant Prostate Cancer

This study was designed to assess the safety and therapeutic response to ¹⁷⁷Lu-labeled Evans blue-modified prostate-specific membrane antigen (PSMA) 617 (EB-PSMA-617) treatment with escalating doses in patients with metastatic castration-resistant prostate cancer. Methods: With institutional review board approval and informed consent, patients were randomly divided into 3 groups: group A (n = 10) was treated with a 1.18 ± 0.09 GBq dose of ¹⁷⁷Lu-EB-PSMA. Group B (n = 10) was treated with a 2.12 ± 0.19 GBq dose of ¹⁷⁷Lu-EB-PSMA. Group C (n = 8) was treated with a 3.52 ± 0.58 GBq dose of ¹⁷⁷Lu-EB-PSMA. Eligible patients received up to 3 cycles of ¹⁷⁷Lu-EB-PSMA therapy, at 8-wk intervals. Results: Because of disease progression or bone marrow suppression, 4 of 10, 5 of 10, and 5 of 8 patients completed 3 cycles of therapy as planned in groups A, B, and C, respectively. The prostate-specific antigen response was correlated with treatment dose, and the prostate-specific antigen disease control rates were higher in groups B (70%) and C (75%) than in group A (10%) (P = 0.007), but no correlation between groups B and C was found. ⁶⁸Ga-PSMA PET/CT showed a response in all treatment groups; however, there was no significant difference among the 3 groups. A hematologic toxicity study found that platelets decreased more in groups B and C than in group A and that grade 4 thrombocytopenia occurred in 2 (25.0%) patients in group C. No serious nephritic or hepatic side effects were observed. Conclusion: This study demonstrated that a 2.12-GBq dose of ¹⁷⁷Lu-EB-PSMA seems to be safe and adequate in tumor treatment. Further investigations with an increased number of patients are warranted.