An update on the use of gonadotropin-releasing hormone antagonists in prostate cancer

Testosterone Recovery for Relugolix Versus Leuprolide in Men with Advanced Prostate Cancer: Results from the Phase 3 HERO Study

BACKGROUND

In the HERO study, relugolix demonstrated sustained testosterone suppression superior to that of leuprolide acetate (97% vs 89%; difference 7.9% [95% confidence interval, 4.1-12%; p < 0.001]).

OBJECTIVE

To analyze testosterone recovery in a prespecified subset of men from the HERO study not indicated to continue androgen deprivation therapy.

DESIGN, SETTING, AND PARTICIPANTS

Men (N = 934) were randomized (2:1) to receive relugolix 120 mg orally daily or leuprolide acetate injections every 12 wk for 48 wk.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Testosterone recovery was assessed in 184 men who completed 48 wk of treatment. During the 90-d recovery period, assessments included time to testosterone recovery (>280 ng/dl; ≥80% of baseline testosterone), serum levels of prostate-specific antigen and pituitary hormones, and adverse events.

RESULTS AND LIMITATIONS

The cumulative incidence rate of testosterone recovery to >280 ng/dl at 90 d following drug discontinuation was significantly higher in the relugolix cohort (n = 137) than in the leuprolide acetate cohort (n = 47; 54% vs 3.2%; nominal p = 0.002). The median time to testosterone recovery was faster following relugolix treatment than with leuprolide acetate treatment (86.0 d vs 112.0 d). Compared with leuprolide acetate, more men treated with relugolix achieved ≥80% of baseline testosterone levels (39% vs 2.1%). Men ≤65 yr and those with baseline testosterone greater than the median had a higher incident rate of testosterone recovery. Adverse events were generally similar between treatment groups. One limitation is the short testosterone recovery follow-up period.

CONCLUSIONS

Oral relugolix had faster and more complete recovery of testosterone to normal levels after treatment discontinuation than leuprolide acetate in a subset of men from the HERO study. The clinical implications of a faster testosterone recovery with relugolix may be significant for men being treated with androgen deprivation therapy and influence treatment decisions.

PATIENT SUMMARY

The male hormone testosterone is reduced during androgen deprivation therapy for prostate cancer. Reduced testosterone levels cause side effects, impacting patient quality of life. When treatment is stopped, the side effects lessen over time as the levels of testosterone come back to pretreatment range (testosterone recovery). In this study, we found that the time to testosterone recovery was faster with relugolix than with leuprolide acetate.

Backbone N-methylation of peptides: Advances in synthesis and applications in pharmaceutical drug development

Peptide-based drugs have garnered considerable attention in recent years owing to their increasingly crucial role in the treatment of diverse diseases. However, the limited pharmacokinetic properties of peptides have hindered their full potential. One prominent strategy for enhancing the druggability of peptides is N-methylation, which involves the addition of a methyl group to the nitrogen atom of the peptide backbone. This modification significantly improves the stability, bioavailability, receptor binding affinity and selectivity of peptide drug candidates. In this review, we provide a comprehensive overview of the advancements in synthetic methods for N-methylated peptide synthesis, as well as the associated limitations. Moreover, we explore the versatile effects of N-methylation on various aspects of peptide properties. Furthermore, we emphasize the efforts dedicated to N-methylated peptide pharmaceuticals that have successfully obtained marketing approval.

Regular use of aspirin is associated with a lower cardiovascular risk in prostate cancer patients receiving gonadotropin-releasing hormone therapy

Gonadotropin-releasing hormone (GnRH) therapy has been known to increase risks of major adverse cardiovascular and cerebrovascular events (MACCEs). Herein, we aim to estimate whether regular use of aspirin attenuates risks of MACCEs in prostate cancer patients receiving GnRHs. Using Taiwanese National Health Insurance Research Database (NHIRD), we identified 7719 patients diagnosed with prostate cancer who were either aspirin-naïve, received irregular or regular aspirin from 2008 to 2015. Through a multivariable logistic regression model, we investigated the impact of aspirin on MACCEs. Compared with nonusers and irregular users, most patients receiving regular aspirin were older and had more comorbidities. The crude incidence of one-year MACCEs was lowest in aspirin nonusers but highest in irregular users of aspirin compared with regular users of aspirin (2.65% vs. 4.41% vs. 2.85%, p=0.0099). After adjusting for age, cancer stage and comorbidities, irregular aspirin users had a higher risk of one-year MACCEs (adjusted OR: 1.33; 95% CI: 0.93-1.90, p=0.1139) than aspirin nonusers, but conversely, there was a trend of reducing the risk of MACCEs among those who received regular aspirin (adjusted OR: 0.79; 95% CI: 0.44-1.42, p=0.4256). In the subgroup analysis, there were age- and cancer stage-independent higher risks of MACCEs in patients who took aspirin irregularly compared to those in patients who did not take aspirin. The risks were attenuated in patients receiving regular aspirin. Collectively, regular use of aspirin presented a trend of reducing risks of MACCEs in prostate cancer patients receiving GnRHs. However, irregular use of aspirin diminished the benefits.

Impact of add-back FSH on human and mouse prostate following gonadotropin ablation by GnRH antagonist treatment

OBJECTIVE

During androgen ablation in prostate cancer by the standard gonadotropin-releasing hormone (GnRH) agonist treatment, only luteinizing hormone (LH) is permanently suppressed while circulating follicle-stimulating hormone (FSH) rebounds. We explored direct prostatic effects of add-back FSH, after androgen ablation with GnRH antagonist, permanently suppressing both gonadotropins.

METHODS

The effects of recombinant human (rFSH) were examined in mice treated with vehicle (controls), GnRH antagonist degarelix (dgx), dgx + rFSH, dgx + flutamide, or dgx + rFSH + flutamide for 4 weeks. Prostates and testes size and expression of prostate-specific and/or androgen-responsive genes were measured. Additionally, 33 young men underwent dgx-treatment. Seventeen were supplemented with rFSH (weeks 1-5), and all with testosterone (weeks 4-5). Testosterone, gondotropins, prostate-specific antigen (PSA), and inhibin B were measured.

RESULTS

In dgx and dgx + flutamide treated mice, prostate weight/body weight was 91% lower than in controls, but 41 and 11%, respectively, was regained by rFSH treatment (P = 0.02). The levels of seminal vesicle secretion 6, Pbsn, Nkx3.1, beta-microseminoprotein, and inhibin b were elevated in dgx + rFSH-treated animals compared with only dgx treated (all P < 0.05). In men, serum inhibin B rose after dgx treatment but was subsequently suppressed by testosterone. rFSH add-back had no effect on PSA levels.

CONCLUSIONS

These data provide novel evidence for the direct effects of FSH on prostate size and gene expression in chemically castrated mice. However, in chemically castrated men, FSH had no effect on PSA production. Whether FSH effects on the prostate in humans also require suppression of the residual adrenal-derived androgens and/or a longer period of rFSH stimulation, remains to be explored.

Pharmacological Treatment for Pedophilic Disorder and Compulsive Sexual Behavior Disorder: A Review

Guidelines for the pharmacological treatment of paraphilic disorders have historically been based on data from forensic settings and on risk levels for sexual crime. However, emerging treatment options are being evaluated for individuals experiencing distress because of their sexual urges and preferences, targeting both paraphilic disorders such as pedophilic disorder (PeD) and the new diagnosis of compulsive sexual behavior disorder (CSBD) included in the International Classification of Diseases, 11th Revision (ICD-11). As in other mental disorders, this may enable individualized pharmacological treatment plans, taking into account components of sexuality (e.g. high libido, compulsivity, anxiety-driven/sex as coping), medical and psychiatric comorbidity, adverse effects and patient preferences. In order to expand on previous reviews, we conducted a literature search focusing on randomized controlled trials of pharmacological treatment for persons likely to have PeD or CSBD. Our search was not restricted to studies involving forensic or criminal samples. Twelve studies conducted between 1974 and 2021 were identified regardless of setting (outpatient or inpatient), with only one study conducted during the last decade. Of a total of 213 participants included in these studies, 122 (57%) were likely to have PeD, 34 (16%) were likely to have a CSBD, and the remainder had unspecified paraphilias (40, 21%) or sexual offense (17, 8%) as the treatment indication. The diagnostic procedure for PeD and/or CSBD, as well as comorbid psychiatric symptoms, has been described in seven studies. The studies provide some empirical evidence that testosterone-lowering drugs reduce sexual activity for patients with PeD or CSBD, but the body of evidence is meager. There is a need for studies using larger samples, specific criteria for inclusion, longer follow-up periods, and standardized outcome measures with adherence to international reporting guidelines.

Current and emerging gonadotropin-releasing hormone (GnRH) antagonists for the treatment of prostate cancer

Introduction:Androgen deprivation therapy (ADT) is currently the backbone treatment of metastatic prostate cancer and is also used in combination with external beam radiotherapy (EBRT). Castration may be achieved either by bilateral orchiectomy or by administration of LHRH agonists or GnRH antagonists.Areas covered: In this article, the authors assess the current and emerging role of GnRH antagonists for the treatment of prostate cancer focusing on oncological results and safety (i.e. cardiovascular risk). In addition, updated data regarding the first orally administered GnRH antagonist, relugolix, is presented.Expert opinion: Studies demonstrate that GnRH antagonists are at least equal with LHRH agonists in terms of testosterone suppression and PSA progression free survival with a major advantage being rapid testosterone suppression. Thus, the optimal group of patients included symptomatic metastatic prostate cancer patients especially if cardiovascular comorbidities or LUTS are also present. Emerging data regarding benefit of the use of GnRH antagonists in patients with concomitant cardiovascular disease are of great interest. Relugolix has emerged as the first orally administered GnRH antagonist able to achieve and maintain testosterone castration levels and it is associated with a profound reduction of major cardiovascular events.

Functionalized Peptide Fibrils as a Scaffold for Active Substances in Wound Healing

Technological developments in the field of biologically active peptide applications in medicine have increased the need for new methods for peptide delivery. The disadvantage of peptides as drugs is their low biological stability. Recently, great attention has been paid to self-assembling peptides that can form fibrils. Such a formulation makes bioactive peptides more resistant to enzymatic degradation and druggable. Peptide fibrils can be carriers for peptides with interesting biological activities. These features open up prospects for using the peptide fibrils as long-acting drugs and are a valid alternative to conventional peptidic therapies. In our study, we designed new peptide scaffolds that are a hybrid of three interconnected amino acid sequences and are: pro-regenerative, cleavable by neutrophilic elastase, and fibril-forming. We intended to obtain peptides that are stable in the wound environment and that, when applied, would release a biologically active sequence. Our studies showed that the designed hybrid peptides show a high tendency toward regular fibril formation and are able to release the pro-regenerative sequence. Cytotoxicity studies showed that all the designed peptides were safe, did not cause cytotoxic effects and revealed a pro-regenerative potential in human fibroblast and keratinocyte cell lines. In vivo experiments in a dorsal skin injury model in mice indicated that two tested peptides moderately promote tissue repair in their free form. Our research proves that peptide fibrils can be a druggable form and a scaffold for active peptides.

Does Exist a Differential Impact of Degarelix Versus LHRH Agonists on Cardiovascular Safety? Evidences From Randomized and Real-World Studies

The main systemic therapy for the management of hormone-sensitive prostate cancer (PC) is androgen deprivation therapy (ADT), with the use of long-acting luteinizing hormone releasing-hormone (LHRH) agonists considered the main form of ADT used in clinical practice to obtain castration in PC. The concomitant administration of antiandrogens for the first weeks could reduce the incidence of clinical effects related to the testosterone flare-up in the first injection of LHRH. On the contrary, Gonadotropin Rh (GnRH) antagonists produce a rapid decrease of testosterone levels without the initial flare-up, with degarelix commonly used in clinical practice to induce castration in PC patients. Even if no long-term data are reported in terms of survival to define a superiority of GnRH or LHRH, for oncological efficacy and PC control, data from randomized clinical trials and from real-life experiences, suggest a difference in cardiovascular risk of patients starting ADT. The age-related decline in testosterone levels may represent a factor connected to the increase of cardiovascular disease risk, however, the role of ADT in increasing CV events remains controversial. For these reasons, the aim of the paper is to synthesize the difference in cardiovascular risk between LHRH and degarelix in patients undergoing ADT. A difference in cardiovascular risk could be indeed an important parameter in the evaluation of these two forms of castration therapy. The Randomized trials analyzed in this paper sustain a possible protective role for degarelix versus LHRH agonists in reducing the rate of new CV events and interventions in the short-term period. On the contrary, real-word data are contradictory in different national experiences and are strongly conditioned by huge differences between the LHRH agonists group and the degarelix group.

Gonadotropin-Releasing Hormone Receptors in Prostate Cancer: Molecular Aspects and Biological Functions

Pituitary Gonadotropin-Releasing Hormone receptors (GnRH-R) mediate the activity of the hypothalamic decapeptide GnRH, thus playing a key role in the regulation of the reproductive axis. Early-stage prostate cancer (PCa) is dependent on serum androgen levels, and androgen-deprivation therapy (ADT), based on GnRH agonists and antagonists, represents the standard therapeutic approach for PCa patients. Unfortunately, the tumor often progresses towards the more aggressive castration-resistant prostate cancer (CRPC) stage. GnRH receptors are also expressed in CRPC tissues, where their binding to both GnRH agonists and antagonists is associated with significant antiproliferative/proapoptotic, antimetastatic and antiangiogenic effects, mediated by the Gαi/cAMP signaling cascade. GnRH agonists and antagonists are now considered as an effective therapeutic strategy for CRPC patients with many clinical trials demonstrating that the combined use of these drugs with standard therapies (i.e., docetaxel, enzalutamide, abiraterone) significantly improves disease-free survival. In this context, GnRH-based bioconjugates (cytotoxic drugs covalently linked to a GnRH-based decapeptide) have been recently developed. The rationale of this treatment is that the GnRH peptide selectively binds to its receptors, delivering the cytotoxic drug to CRPC cells while sparing nontumor cells. Some of these compounds have already entered clinical trials.

Therapies Targeted to Androgen Receptor Signaling Axis in Prostate Cancer: Progress, Challenges, and Hope

Prostate cancer is the mostly commonly diagnosed non-cutaneous malignancy and the second leading cause of cancer-related death affecting men in the United States. Moreover, it disproportionately affects the men of African origin, who exhibit significantly greater incidence and mortality as compared to the men of European origin. Since androgens play an important role in the growth of normal prostate and prostate tumors, targeting of androgen signaling has remained a mainstay for the treatment of aggressive prostate cancer. Over the years, multiple approaches have been evaluated to effectively target the androgen signaling pathway that include direct targeting of the androgens, androgen receptor (AR), AR co-regulators or other alternate mechanisms that impact the outcome of androgen signaling. Several of these approaches are currently in clinical practice, while some are still pending further development and clinical evaluation. This remarkable progress has resulted from extensive laboratory, pre-clinical and clinical efforts, and mechanistic learnings from the therapeutic success and failures. In this review, we describe the importance of androgen signaling in prostate cancer biology and advances made over the years to effectively target this signaling pathway. We also discuss emerging data on the resistance pathways associated with the failure of various androgen signaling- targeted therapies and potential of this knowledge for translation into future therapies for prostate cancer.

Degarelix treatment is compatible with diabetes and antithrombotic therapy in patients with prostate cancer

Introduction

Therapeutically induced androgen deficiency (AD) is a standard treatment for patients with prostate cancer, but it is often associated with various adverse effects (AEs) that may lead to discontinuation. Some AEs may depend on the patient's health condition, while others may be due to complications of the drug delivery method. Degarelix is a gonadotropin-releasing hormone (GnRH) antagonist widely used for the treatment of androgen-dependent prostate cancer. This study aimed to ascertain the following: 1) the compatibility of degarelix treatment with diabetes and 2) any specific causal associations of degarelix injections with increased blood clotting and antithrombotic therapy requirements.

Patients and methods

The medical records of 162 patients with prostate cancer who had undergone degarelix treatment were retrospectively examined. The association of a medical history of diabetes and anticoagulant co-treatment with degarelix treatment discontinuation was analyzed statistically.

Results

Rapid and significant decreases in prostate-specific antigen (PSA) levels during the course of degarelix treatment were detected for patients with prostate cancer regardless of clinical state. During the 27 months of treatment, 68 subjects (48%) ceased degarelix treatment, owing to several reasons, mainly financial issues. Among these subjects, 19 had diabetes, while 35 were treated with antithrombotics. Extensive statistical analysis indicated that there were no causal associations between degarelix treatment discontinuation and preexisting diabetes or antithrombotic therapy.

Conclusion

Our study suggests that preexisting diabetes and antithrombotic therapy were not significant factors for the discontinuation of degarelix treatment in patients with prostate cancer.

Efficacy and safety of a 3-month dosing regimen of degarelix in Japanese patients with prostate cancer: a phase II maintenance-dose-finding study

Objective

To evaluate the efficacy and safety of degarelix 3-month depot in Japanese patients with prostate cancer.

Methods

In this Phase II, open-label, parallel-group study, 155 Japanese prostate cancer patients were randomized to treatment with degarelix administered subcutaneously at a maintenance dose of 360 or 480 mg every 84 days for 12 months, after receiving an initial dose of 240 mg. The primary endpoint was the cumulative probability of serum testosterone ≤0.5 ng/ml (Days 28–364). Secondary endpoints included percent change in serum prostate-specific antigen level and proportion of patients with prostate-specific antigen failure at Day 364. For safety, adverse events were evaluated.

Results

The cumulative probability of serum testosterone ≤0.5 ng/ml (Days 28–364) was 88.3% (95% confidence interval: 77.9–94.0%) and 97.2% (95% confidence interval: 89.4–99.3%) in the 360 and 480 mg groups, respectively. The median percent change in serum prostate-specific antigen level from baseline to Day 364 was −95.05% and −96.43% in the 360 and 480 mg groups, respectively; the proportion of patients with prostate-specific antigen failure was 2.7% and 1.3%. The most frequent adverse event was injection site reaction; however, this did not cause any patient to discontinue treatment.

Conclusions

The 3-month dosing regimen of degarelix 360/480 mg was effective and well tolerated for treatment of Japanese prostate cancer patients. The 480 mg group showed a higher cumulative castration rate than the 360 mg group; thus, 480 mg was considered to be the optimal clinical dosage for future Phase III trials.

Effect of Degarelix, a Gonadotropin-Releasing Hormone Receptor Antagonist for the Treatment of Prostate Cancer, on Cardiac Repolarisation in a Randomised, Placebo and Active Comparator Controlled Thorough QT/QTc Trial in Healthy Men

BACKGROUND AND OBJECTIVES

Degarelix is a gonadotropin-releasing hormone antagonist registered for the treatment of advanced hormone-dependent prostate cancer. Treatment causing androgen deprivation is associated with QT prolongation and this study investigated whether degarelix at supratherapeutic concentrations has an intrinsic effect per se on cardiac repolarisation and the QT interval.

METHODS

This was a single-centre, randomised, crossover study comparing the effect of degarelix, placebo, and the positive control moxifloxacin on the QT interval. Degarelix and placebo treatments were double-blind, whereas moxifloxacin treatment was open-label. Eighty healthy men, aged 18-45 years, received single intravenous doses of degarelix 2.8 mg, and placebo, as well as a single oral dose of moxifloxacin 400 mg. Electrocardiograms were collected up to 24 h after the start of administration, with the QT interval assessed and plasma concentrations of degarelix concomitantly analysed.

RESULTS

Time-matched, one-sided 95% upper confidence boundaries for baseline-corrected average changes from placebo for the QT interval, corrected using the Fridericia method (ΔΔQTcF), did not exceed 10 ms at any timepoint, with maximum degarelix concentrations reaching approximately threefold the concentrations seen in the treatment of prostate cancer. Furthermore, concentration-exposure analysis indicated absence of any QT prolongation effects of degarelix. No significant effect on any other cardiac parameter was observed. The lower bound of the 98.3% confidence interval for moxifloxacin ΔΔQTcF exceeded 5 ms, thus verifying assay sensitivity.

CONCLUSION

The results showed that the study was validated to detect a significant effect on the QT interval, and that degarelix by itself does not have any effect on the QT interval and cardiac repolarisation at supratherapeutic concentrations.

Pharmacotherapeutic Targeting of G Protein-Coupled Receptors in Oncology: Examples of Approved Therapies and Emerging Concepts

G protein-coupled receptors (GPCRs) are involved in numerous physio-pathological processes, including the stimulation of cancer progression. In this regard, it should be mentioned that although GPCRs may represent major pharmaceutical targets, only a few drugs acting as GPCR inhibitors are currently used in anti-tumor therapies. For instance, certain pro-malignancy effects mediated by GPCRs are actually counteracted by the use of small molecules and peptides that function as receptor antagonists or inverse agonists. Recently, humanized monoclonal antibodies targeting GPCRs have also been developed. Here, we review the current GPCR-targeted therapies for cancer treatment, summarizing the clinical studies that led to their official approval. We provide a broad overview of the mechanisms of action of the available anti-cancer drugs targeting gonadotropin-releasing hormone, somatostatin, chemokine, and Smoothened receptors. In addition, we discuss the anti-tumor potential of novel non-approved molecules and antibodies able to target some of the aforementioned GPCRs in different experimental models and clinical trials. Likewise, we focus on the repurposing in cancer patients of non-oncological GPCR-based drugs, elucidating the rationale behind this approach and providing clinical evidence on their safety and efficacy.

Degarelix versus luteinizing hormone-releasing hormone agonists for the treatment of prostate cancer

INTRODUCTION

Androgen deprivation therapy (ADT) is the mainstay for advanced, hormone-sensitive prostate cancer, and options include surgical castration, luteinizing hormone-releasing hormone (LHRH) agonist, and more recently, gonadotropin releasing hormone (GnRH) antagonist therapy. Our understanding of the mechanisms and adverse effects of ADT has increased substantially, including the class-specific adverse effects of ADT. Areas covered: This review will summarize the pharmacodynamic and pharmacokinetic properties of the GnRH antagonist degarelix and its role in the management of advanced prostate cancer, the clinical evidence supporting its regulatory approval, as well as potential benefits and disadvantages over traditional LHRH agonist therapy. Expert opinion: Degarelix represents a newer class of ADT that results in a rapid and reliable decline in serum testosterone, a quality that makes it particularly advantageous in men presenting with symptomatic, hormone-sensitive prostate cancer. Due to differences in mechanism of action, there is observational data suggesting a potential cardiovascular and even oncologic benefit over traditional LHRH agonist therapy. Further research is ongoing to more clearly define this potential benefit.

Overview of elagolix for the treatment of endometriosis

INTRODUCTION

Suppression of sex-steroid secretion is required in a variety of gynecological conditions. This can be achieved using gonadotropin releasing hormone (GnRH) agonists that bind pituitary gonadotropin receptors and antagonize the link-receptor of endogenous GnRH, inhibiting the mechanism of GnRH pulsatility. On the other hand, GnRH antagonists immediately reduce gonadal steroid levels, avoiding the initial stimulatory phase of the agonists. Potential benefits of GnRH antagonists over GnRH agonists include a rapid onset and reversibility of action. Older GnRH antagonists are synthetic peptides, obtained by modifications of certain amino acids in the native GnRH sequence. They require subcutaneous injections, implantation of long-acting depots. The peptide structure is responsible for histamine-related adverse events and the tendency to elicit hypersensitivity reactions.

AREAS COVERED

Research has worked towards the development of non-peptidic molecules exerting antagonist action on GnRH. They are available for oral administration and may have a more beneficial safety profile in comparison with peptide GnRH antagonists. This article focuses on the data of the literature about elagolix, a novel non-peptidic GnRHantagonist, in the treatment of endometriosis.

EXPERT OPINION

Elagolix demonstrated efficacy in the management of endometriosis-associated pain and had an acceptable safety and tolerability profile. However, further studies are necessary to evaluate its non-inferiority in comparison with other endometriosis's treatments.

Effects of long-acting GnRH antagonist, degarelix acetate, on plasma insulin-like peptide 3, testosterone and luteinizing hormone concentrations, and scrotal circumference in male goats

We recently reported that plasma insulin-like peptide 3 (INSL3) concentrations increased soon after endogenous and exogenous stimulations of LH in male goats and bulls. However, the effects of LH suppression on INSL3 secretion are unknown in domestic animals. Here, we examined the effects of a long-acting GnRH antagonist (degarelix acetate; 4 mg/kg) on the secretions of plasma INSL3 and testosterone in two phases, an immediate and a long-term phase in male goats (n = 6; aged, 13-16 months). During the immediate phase, blood was taken at 15-minute intervals for 8 hours on Days -5, 0, and 3. The GnRH antagonist was administered after 2-hour sampling of Day 0. Moreover, a daily blood sample was taken from Day 0 to Day 7, followed by twice a week until 9 weeks and finally at week 10. The scrotal circumference was recorded before treatment and continued biweekly until week 10. Concentrations of LH, INSL3, and testosterone in plasma were determined by EIA and the pulsatile nature of secretion analyzed using pulse XP software. The mean concentrations, pulse frequency (per hour), and pulse amplitude (peak-nadir) of plasma LH and testosterone reduced from pretreatment to posttreatment Day 0 and Day 3 (P < 0.05). A decline in mean concentrations, pulse frequency, and pulse amplitude of INSL3 was exhibited on posttreatment Day 3 compared with pretreatment (P < 0.01). During long-term sampling, a decline (P < 0.01) in plasma testosterone and INSL3 concentrations was observed 1 day after treatment and remained lower until 8.5 weeks after treatment, and thereafter returned to pretreatment levels. A reduction in scrotal circumference was recorded 4 weeks after treatment and remained lower until 10 weeks after treatment (P < 0.05). In conclusion, the acute regulation of INSL3 by LH was confirmed by reduction of plasma INSL3 levels within 3 days after GnRH antagonist treatment in male goats. Although the onset of suppression of testosterone was more rapid than that of INSL3, the low levels persisted for 8.5 weeks for both hormones, and subsequently the concentrations returned to pretreatment levels. A significant reduction in testicular size was also observed. The quick, long-lasting, and transient suppression of testosterone and INSL3 after a single injection implies a potential application of this antagonist in reversible long-term chemical castration in male goats.

The role of gonadotrophin-releasing hormone antagonists in the treatment of patients with advanced hormone-dependent prostate cancer in the UK

Purpose

Comparing gonadotrophin-releasing hormone (GnRH) antagonists and agonists as androgen deprivation therapy for advanced prostate cancer (PC).

Methods

This article stems from a round-table meeting in December 2014 to compare the properties of GnRH agonists and antagonists in the published literature in order to identify the patient groups most likely to benefit from GnRH antagonist therapy. A broad PubMed and congress abstract search was carried out in preparation for the meeting to ensure that the latest data and opinion were available for the discussions.

Results

In randomised, controlled trials, GnRH antagonist therapy provides more rapid suppression of luteinising hormone, follicle-stimulating hormone and testosterone than GnRH agonist treatment. Compared with the GnRH agonist, there is evidence of improved disease control by a GnRH antagonist, with longer interval to prostate-specific antigen progression and greater reduction of serum alkaline phosphatase. In a post hoc analysis of six randomised trials, the risk of cardiac events within 1 year of initiating therapy was significantly lower among men receiving GnRH antagonist than agonist. Pre-clinical laboratory data suggest a number of mechanisms whereby GnRH antagonist therapy may benefit men with pre-existing cardiovascular disease (CVD), the most plausible hypothesis being that, unlike GnRH agonists, GnRH antagonists do not activate T lymphocytes, which act to increase atherosclerotic plaque rupture.

Conclusion

When making treatment decisions, clinicians should consider comorbidities, particularly CVD, in addition to effects on PC. GnRH antagonists may be appropriate in patients with significant CV risk, existing osteopenia, lower urinary tract symptoms and significant metastatic disease.

Degarelix for the treatment of advanced prostate cancer compared with GnRh-Agonists: a systematic review and meta-analysis

BACKGROUND

Hormone therapy is currently the mainstay in the management of locally advanced and metastatic prostate cancer. We performed a systematic review to compare safety, efficacy and effectiveness of degarelix, a new gonadotropin-releasing hormone (GnRH) antagonist (blocker), versus gonadotropin-releasing hormone (GnRH) agonists.

METHODS

MEDLINE, Web of Science and the Cochrane library were searched to identify all of the published Randomized Controlled Trials (RCTs) that used degarelix versus gonadotropin-releasing hormone agonists with or without anti-androgen therapy for the treatment of prostate cancer. We performed meta-analysis of extracted data on safety and efficacy of the target medication.

RESULTS

Six studies were included. They involved a total of 2296 patients which were used in the meta-analysis. Follow-up times after treatment were between 12 weeks and 12 months. Three of six RCTs compared degarelix with goserelin and the others compared it with leuprolide. Meta-analysis on safety outcomes revealed that the only statistically significant difference between the degarelix treated group and GnRH agonists treated group was complication in the injection site which was higher in degarelix-treated group (OR= 46.34, 95% CI: 15.79 to 136, p<0.001). Although general mortality rate was lower in degarelix-treated group (OR= 2.06, 95% CI: 1.08 to 3.93, p=0.03); mortality due to the drug side effects was not different. Meta-analysis of efficacy data also showed that International Prostate Symptom Score (IPSS) reduction at week 12, (MD=-1.85, 95% CI: -2.97 to - 0.72, p=0.001) and Testosterone reduction between day 1-28, (OR=11.58, 95% CI: 5.77 to 23.22, p<0.001) was statistically higher in degarelix-treated group. Testosterone reduction after day 28 and prostate volume reduction did not have significant difference.

CONCLUSION

Our meta-analysis indicates that, compared with GnRH agonists, degarelix has significantly more effects on lower urinary tract symptoms and also Prostate Specific Antigen (PSA) and testosterone reduction in the first month of the treatment. Except minor complications in the injection site like pain, erythema and swelling, there is no increase in major side effects and mortality due to degarelix. This is while the effect on testosterone and PSA after the first month of treatment is not statistically different between the two groups.

Pharmacokinetic and pharmacodynamic profile of degarelix for prostate cancer

INTRODUCTION

Luteinizing hormone-releasing hormone (LHRH) agonists have been the mainstay of androgen deprivation therapy (ADT) for advanced prostate cancer for over two decades. However, their limitations include a transient initial rise in testosterone, failure to reduce testosterone to castrate levels in some patients, incomplete suppression of follicle-stimulating hormone (FSH), and an increased risk of cardiovascular (CV) events in those with pre-existing CV disease. This article considers whether the LHRH antagonist degarelix offers significant advantages over LHRH agonists.

AREAS COVERED

This review covers the development and introduction of degarelix, its pharmacodynamic and pharmacokinetic properties, and the efficacy and safety results of Phase II and III clinical studies.

EXPERT OPINION

Degarelix has clear pharmacodynamic advantages over the LHRH agonist leuprolide in terms of almost immediate suppression of testosterone to castrate levels and sustained suppression of FSH levels. It reduces the risk of CV events vs agonists in men with pre-existing CV disease. This finding, which may reflect differential effects on FSH and/or endothelial plaques, requires confirmation in a prospective study; however, it is the view of the author that the differential effects on CV events are real and suggest that men with pre-existing CV disease requiring ADT should preferentially be treated with degarelix.

Prior administration of a non-steroidal anti-androgen failed to prevent the flare-up caused by a luteinizing hormone-releasing hormone agonist in a patient with metastatic prostate cancer

Background

‘Flare phenomenon’ after initial luteinizing hormone-releasing hormone agonist administration is a widely approved concept in the treatment of prostate cancer. In most guidelines, concomitant therapy with anti-androgens is recommended to prevent this flare phenomenon. However, there are few reports describing serum prostate-specific antigen transitions after hormonal therapy. Here, we present a case of a man who experienced the biochemical and clinical flare phenomenon despite prior anti-androgen use and who has detailed data.

Case presentation

A 70-year-old Asian man with metastatic prostate cancer (multiple bone) was referred to our hospital. He was treated with prior anti-androgens and luteinizing hormone-releasing hormone agonist. Regardless of prior use of anti-androgens, his low back pain caused by bone metastases was deteriorated and serum prostate-specific antigen level was raised from 974.8 ng/mL to 2,555.5 ng/mL within 3 weeks. Then, his serum prostate specific antigen level started to decrease along with the pain. The nadir reached 1.0 ng/mL and remained for 6 months. Because the serum level of prostate-specific antigen then began to increase again, anti-androgen was discontinued for anti-androgen withdrawal syndrome. Then the serum level decreased again to less than 0.1 ng/mL. Until now, his serum prostate-specific antigen level has been maintained at less than 0.1 ng/mL for more than 30 months without any clinical progressions.

Conclusion

We present the case of a patient in whom a clinical flare caused by an leuteinizing hormone-releasing hormone agonist was not prevented by prior anti-androgen administration. In addition, the nadir level of prostate-specific antigen when he received leuteinizing hormone-releasing hormone monotherapy was ten times lower than when he received concomitant therapy, and period of anti-androgen withdrawal syndrome was longer than usual. In this case, anti-androgen was probably not effective from the initial administration. Awareness of the possibility of ineffectiveness of anti-androgens is important in the treatment of symptomatic metastatic prostate cancer. Leuteinizing hormone-releasing hormone antagonist and surgical castration is a more reliable clinical approach for the prostate cancer patients with symptomatic metastatic disease.

Degarelix: a review of its use in patients with prostate cancer

Degarelix (Firmagon(®); Gonax(®)) is a gonadotropin-releasing hormone receptor antagonist that is approved for the treatment of advanced (hormone-dependent) prostate cancer in the US and EU and the treatment of prostate cancer in Japan. In a pivotal randomized, controlled, 12-month phase III study, degarelix (initial subcutaneous dose of 240 mg followed by monthly dosages of 80 mg) was noninferior to leuprolide (monthly intramuscular dosages of 7.5 mg) in patients with prostate cancer of any stage for which endocrine treatment was indicated (except neoadjuvant hormonal therapy) with regard to suppression of testosterone to castration levels (i.e. ≤0.5 ng/mL). Suppression of testosterone and prostate-specific antigen (PSA) levels was faster with degarelix than with leuprolide, and no testosterone surges or microsurges were seen in degarelix recipients. Suppression of testosterone and PSA levels was maintained for the 12-month study duration and continued for up to 5 years in an extension to the main trial (including in patients switching from leuprolide to degarelix in the extension). The drug was generally well tolerated, with most adverse events being mild to moderate in severity. Injection-site reactions and events reflecting the expected effects of testosterone suppression (e.g. hot flushes, weight increase) were the most common treatment-emergent adverse events. Thus, degarelix is a useful option for the treatment of prostate cancer in patients for whom endocrine treatment is indicated.

An approach to asymmetric synthesis of β-aryl alanines by Pd(0)-catalyzed cross-coupling and cyanate-to-isocyanate rearrangement

A new method for the asymmetric synthesis of β-aryl alanines is reported.

Autophagy in prostate cancer and androgen suppression therapy

The role of autophagy is known to be highly complex and context-dependent, leading to both cancer suppression and progression in several tumors including melanoma, breast and prostate cancer. In the present review, recent advances in an understanding of the involvement of autophagy in prostate cancer treatment are described. The regulatory effects of androgens on prostate cancer cell autophagy are particularly discussed in order to highlight the effects of autophagy modulation during androgen deprivation. A critical evaluation of the studies examined in the present review suggests the attractive possibility of autophagy inhibition combined with hormonal therapy as a promising approach for prostate cancer treatment.

Clinical significance of suboptimal hormonal levels in men with prostate cancer treated with LHRH agonists

PURPOSE

We examined the serum levels of testosterone (T) (total and bioavailable) dehydroepiandrosterone (DHEA), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prostate-specific antigen (PSA) in men receiving treatment with luteinizing hormone releasing-hormone (LHRH) agonists for metastatic prostate cancer. In doing this, we want to determine the efficacy of these agents in lowering T levels and whether a possible relationship exists between PSA values, as a surrogate measure of tumour activity, and hormone levels.

METHODS

This was a single centre prospective study of patients on LHRH agonists. Of all the 100 eligible patients, 31 did not qualify (10 were receiving their first injection, 13 were on intermittent hormonal therapy, 7 refused to enter the trial and 1 patient's blood sample was lost). Therefore in total, 69 patients were included in the final analysis. Each patient had their blood sample drawn immediately before the administration of a LHRH agonist. The new proposed criteria of <20 ng/dL (0.69 nmol/L) of total testosterone was used to define optimal levels of the hormone in this population.

RESULTS

Of the 69 patients, 41 were on goserelin injections, 21 on leuprolide, and 7 on buserelin. There was no statistical difference in hormone levels between any of the medications. Overall, 21% of patients failed to reach optimal levels of total testosterone. PSA levels were higher in this group. There was a statistically significant correlation between PSA and testosterone levels, as well as between PSA and FSH. Serum levels of PSA, however, did not correlate with those of bioavailable testosterone.

CONCLUSIONS

Failure to reach optimal levels of testosterone occurs in patients on LHRH agonist therapy. Higher PSA values are more commonly found in patients with suboptimal levels of testosterone receiving LHRH analogs, but the clinical importance of this finding has not been established. There is no significant difference with respect to hormonal levels reached among patients on a variety of LHRH agonists. Total testosterone determinations should be considered in patients on LHRH agonist therapy, particularly when the PSA values begin to rise since it may lead to further beneficial hormonal manipulation.

An update on the use of degarelix in the treatment of advanced hormone-dependent prostate cancer

Androgen deprivation therapy remains the mainstay of medical treatment for advanced prostate cancer. Commonly, this is achieved with medical androgen deprivation rather than surgical intervention as the permanence and psychological effects of the latter are unacceptable for most patients. Degarelix is a third generation antagonist of luteinizing hormone-releasing hormone (LHRH, also termed gonadotropin-releasing hormone) for the first-line treatment of androgen-dependent advanced prostate cancer. Degarelix acts directly on the pituitary receptors for LHRH, blocking the action of endogenous LHRH. The use of degarelix eliminates the initial undesirable surge in gonadotropin and testosterone levels, which is produced by agonists of LHRH. Degarelix is the most comprehensively studied and widely available LHRH antagonist worldwide. Clinical trials have demonstrated that degarelix has a long-term efficacy similar to the LHRH agonist leuprolide in achieving testosterone suppression in patients with prostate cancer. Degarelix, however, produces a faster suppression of testosterone and prostate-specific antigen (PSA), with no testosterone surges or microsurges, and thus prevents the risk of clinical flare in advanced disease. Recent clinical trials demonstrated that treatment with degarelix results in improved disease control when compared with an LHRH agonist in terms of superior PSA progression-free survival, suggesting that degarelix likely delays progression to castration-resistant disease and has a more significant impact on bone serum alkaline phosphatase and follicle-stimulating hormone. Degarelix is usually well tolerated, with limited toxicity and no evidence of systemic allergic reactions in clinical studies. Degarelix thus represents an important addition to the hormonal armamentarium for therapy of advanced androgen-dependent prostate cancer.

Experience with degarelix in the treatment of prostate cancer

Degarelix is a gonadotrophin-releasing hormone (GnRH) antagonist for the first-line treatment of androgen-dependent advanced prostate cancer. It has a direct mechanism of action that blocks the action of GnRH on the pituitary with no initial surge in gonadotrophin or testosterone levels. Degarelix is the most extensively studied and widely available GnRH antagonist worldwide. Clinical studies have demonstrated similar efficacy to the GnRH agonist leuprolide in achieving testosterone suppression in patients with prostate cancer. However, degarelix produces a faster suppression of testosterone and prostate-specific antigen (PSA), with no testosterone surge or microsurges, thus preventing the risk of clinical flare in advanced disease. Clinical trials have demonstrated that degarelix can offer improved disease control when compared with a GnRH agonist in terms of superior PSA progression-free survival (suggesting that degarelix likely delays progression to castration-resistant disease), and a more significant impact on bone serum alkaline phosphatase and follicle-stimulating hormone. Degarelix is generally well tolerated, with no reports of systemic allergic reactions in any clinical studies. In conclusion, degarelix offers clinicians a rational first-line hormonal monotherapy option for the management of advanced prostate cancer.

Progress in emerging therapies for advanced prostate cancer

The landscape of prostate cancer treatment is rapidly changing as extensive research into potential therapies yields new options. In this article, the literature is reviewed to identify emerging therapies for advanced prostate cancer. Emphasis is placed on agents that have been approved in the United States of America (USA) and the European Union, or that have reached phase III clinical studies. Several new therapies have been approved in recent years across different stages of the natural history of the disease. Degarelix, a luteinizing hormone-releasing hormone antagonist, has been approved for reducing testosterone to castrate levels in hormone-sensitive disease. No new agents have been approved for use in combination with docetaxel chemotherapy, the current standard of care for metastatic castration-resistant prostate cancer. One immunotherapy, sipuleucel-T, has been approved (USA only) in the pre-docetaxel setting. Cabazitaxel, a next-generation taxane, and abiraterone acetate, an inhibitor of androgen biosynthesis, have both been approved as second-line agents following chemotherapy. Enzalutamide (MDV3100), an androgen receptor antagonist, has been shown to increase overall survival in the post-chemotherapy setting in metastatic disease. Denosumab, an antibody-based bone-targeted agent, has been approved for the prevention of skeletal-related events in patients with bone metastases. Radium-223 chloride, an α-emitting radiopharmaceutical, is likely to gain approval soon following promising results in a phase III trial. Clinical studies involving other promising agents are ongoing. The emergence of these therapies adds to the growing armamentarium against prostate cancer.

GnRH receptors in cancer: from cell biology to novel targeted therapeutic strategies

The crucial role of pituitary GnRH receptors (GnRH-R) in the control of reproductive functions is well established. These receptors are the target of GnRH agonists (through receptor desensitization) and antagonists (through receptor blockade) for the treatment of steroid-dependent pathologies, including hormone-dependent tumors. It has also become increasingly clear that GnRH-R are expressed in cancer tissues, either related (i.e. prostate, breast, endometrial, and ovarian cancers) or unrelated (i.e. melanoma, glioblastoma, lung, and pancreatic cancers) to the reproductive system. In hormone-related tumors, GnRH-R appear to be expressed even when the tumor has escaped steroid dependence (such as castration-resistant prostate cancer). These receptors are coupled to a G(αi)-mediated intracellular signaling pathway. Activation of tumor GnRH-R by means of GnRH agonists elicits a strong antiproliferative, antimetastatic, and antiangiogenic (more recently demonstrated) activity. Interestingly, GnRH antagonists have also been shown to elicit a direct antitumor effect; thus, these compounds behave as antagonists of GnRH-R at the pituitary level and as agonists of the same receptors expressed in tumors. According to the ligand-induced selective-signaling theory, GnRH-R might assume various conformations, endowed with different activities for GnRH analogs and with different intracellular signaling pathways, according to the cell context. Based on these consistent experimental observations, tumor GnRH-R are now considered a very interesting candidate for novel molecular, GnRH analog-based, targeted strategies for the treatment of tumors expressing these receptors. These agents include GnRH agonists and antagonists, GnRH analog-based cytotoxic (i.e. doxorubicin) or nutraceutic (i.e. curcumin) hybrids, and GnRH-R-targeted nanoparticles delivering anticancer compounds.

The effect of baseline testosterone on the efficacy of degarelix and leuprolide: further insights from a 12-month, comparative, phase III study in prostate cancer patients

OBJECTIVE

To investigate the effects of baseline testosterone on testosterone control and prostate-specific antigen (PSA) suppression using data from a phase III trial (CS21) comparing degarelix and leuprolide in prostate cancer.

METHODS

In CS21, patients with histologically confirmed prostate cancer (all stages) were randomized to degarelix 240 mg for 1 month followed by monthly maintenance doses of 80 or 160 mg, or leuprolide 7.5 mg/month. Patients receiving leuprolide could receive antiandrogens for flare protection. Treatment effects on testosterone and PSA reduction, testosterone surge, and microsurges were investigated in 3 baseline testosterone subgroups: <3.5, 3.5-5.0, and >5.0 ng/mL. Data are presented for the groups receiving degarelix 240/80 mg (the approved dose) and leuprolide 7.5 mg.

RESULTS

Higher baseline testosterone delayed castration with both treatments. However, castrate testosterone levels and PSA suppression occurred more rapidly with degarelix irrespective of baseline testosterone. With leuprolide, the magnitude of testosterone surge and microsurges increased with increasing baseline testosterone. There was no overall correlation between baseline testosterone and initial PSA decrease in either treatment group, although PSA suppression tended to be slowest with leuprolide and fastest with degarelix in the high baseline testosterone subgroup.

CONCLUSION

Patients with high baseline testosterone may have greater risk of tumor stimulation (clinical flare) and mini-flares during gonadotrophin-releasing hormone agonist treatment and so the need for flare protection with antiandrogens in these patients is obvious, especially in metastatic disease. Although higher baseline testosterone delays castration, castrate testosterone and PSA suppression occur more rapidly with degarelix, irrespective of baseline testosterone, without the need for flare protection.

Androgen deprivation therapy: past, present and future

Since Huggins and Hodges demonstrated the responsiveness of prostate cancer to androgen deprivation therapy (ADT), androgen-suppressing strategies have formed the cornerstone of management of advanced prostate cancer. Approaches to ADT have included orchidectomy, oestrogens, luteinizing hormone-releasing hormone (LHRH) agonists, anti-androgens and more recently the gonadotrophin-releasing hormone antagonists. The most extensively studied antagonist, degarelix, avoids the testosterone surge and clinical flare associated with LHRH agonists, offering more rapid PSA and testosterone suppression, improved testosterone control and improved PSA progression-free survival compared with agonists. The clinical profile of degarelix appears to make it a particularly suitable therapeutic option for certain subgroups of patients, including those with metastatic disease, high baseline PSA (>20 ng/mL) and highly symptomatic disease. As well as forming the mainstay of treatment for advanced prostate cancer, ADT is increasingly used in earlier disease stages. While data from clinical trials support the use of ADT neoadjuvant/adjuvant to radiotherapy for locally advanced or high-risk localized prostate cancer, it remains to be established whether specific ADT classes/agents provide particular benefits in this clinical setting.

New considerations for ADT in advanced prostate cancer and the emerging role of GnRH antagonists

Androgen deprivation therapy (ADT) is first-line treatment for metastatic prostate cancer (PCa). Gonadotrophin-releasing hormone (GnRH) agonists are the most commonly used ADT but have several theoretical physiologic disadvantages (e.g. initial testosterone surge, potential microsurges upon repeat administration). Testosterone surge delays the intended serologic endpoint of testosterone suppression and may exacerbate clinical symptoms. GnRH antagonists were developed with a view toward overcoming these potential adverse physiologic events. This review evaluates GnRH agonists and antagonists, assessing the potential future role of antagonists in PCa and strategies to minimize ADT adverse events (AEs). Evidence was identified via PubMed search (by GnRH agent and other ADT-related terms), from review article bibliographies, and authors' therapy area knowledge, with articles included by author consensus. Degarelix shows similar efficacy to a GnRH agonist in achieving and maintaining castration, with faster onset and without testosterone surge/microsurges. Phase III data showed that, in the first treatment year, degarelix displayed a lower risk of PSA failure or death (composite endpoint), lower levels of the bone marker serum alkaline phosphatase (in baseline metastatic disease), and fewer musculoskeletal AEs than the agonist leuprolide. Also, crossing over from leuprolide to degarelix after 1 year reduced the risk of PSA failure or death. ADT displays an AE spectrum which can impact quality of life as well as causing significant morbidities. Strategies to improve ADT tolerability have become increasingly important including: a holistic management approach, improved diet and exercise, more specific monitoring to detect and prevent testosterone depletion toxicities, and intermittent ADT allowing hormonal recovery between treatment periods. Clinical studies suggest possible benefits of GnRH antagonists over agonists based on different mechanisms of action. GnRH antagonists should now be considered as an alternative first-line ADT option in advanced PCa. Intermittent ADT and a holistic treatment approach are promising strategies to improve ADT tolerability.

Gonadotropin-releasing hormone: an update review of the antagonists versus agonists

Gonadotropin-releasing hormone agonists and antagonists provide androgen-deprivation therapy for prostate cancer. Unlike agonists, gonadotropin-releasing hormone antagonists have a direct mode of action to block pituitary gonadotropin-releasing hormone receptors. There are two licensed gonadotropin-releasing hormone antagonists, degarelix and abarelix. Of these, degarelix is the more extensively studied and has been documented to be more effective than the well-established, first-line agonist, leuprolide, in terms of substantially faster onset of castration, faster suppression of prostate-specific antigen, no risk for testosterone surge or clinical flare, and improved prostate-specific antigen progression-free survival, suggesting a delay in castration resistance. Other than minor injection-site reactions, degarelix is generally well tolerated, without systemic allergic reactions and with most adverse events consistent with androgen suppression or the underlying condition. In conclusion, degarelix provides a rational, first-line androgen-deprivation therapy suitable for the treatment of prostate cancer, with faster onset of castration than with agonists, and no testosterone surge. Furthermore, data suggest that degarelix improves disease control compared with leuprolide, and might delay the onset of castration-resistant disease. In view of these clinical benefits and the lack of need for concomitant anti-androgen treatment, gonadotropin-releasing hormone antagonists might replace gonadotropin-releasing hormone agonists as first-line androgen-deprivation therapy in the future.

Toxicarioside A, isolated from tropical Antiaris toxicaria, blocks endoglin/TGF-β signaling in a bone marrow stromal cell line

OBJECTIVE

To investigate possible mechanism of toxicarioside A in HS-5 bone stromal cells.

METHODS

HS-5 bone stromal cells were cultured in media supplemented with various concentrations of toxicarioside A or control DMSO (not treatment). Endoglin and TGF-β were detected by Northern and Western blot analysis and quantified in a standard method. Downstream molecules of endoglin and TGF-β (Smad1, Smad2 and their active phosphorylated counterparts, pSmad1 and pSmad2) were also detected and quantified by Western blot analysis. In addition, cell proliferation assay and small interfering RNA (siRNA) against endoglin were used to certificate the function of endolgin in the HS-5 cells.

RESULTS

Compared with the not treated (0 μg/mL) or DMSO treated control HS-5 cells, HS-5 cells treated with toxicarioside A were found significant attenuation of endolgin and TGF-β expression. Significant inhibition of cell proliferation was also found in the HS-5 cells treated with toxicarioside A. ALK1-related Smad1 and ALK5-related Smad2 were decreased in HS-5 cells treated with toxicarioside A. In addition, phosphorylated Smad1 (pSmad1) and Smad2 (pSmad2) were also found attenuation in toxicarioside A-treated HS-5 cells. RNA interference showed that blockage of endoglin by siRNA also decreased Smad1 and Smad2 expression in HS-5 cells.

CONCLUSIONS

Our results indicate that toxicarioside A can influence bone marrow stromal HS-5's function and inhibit HS-5 cell proliferation by alteration of endoglin-related ALK1 (Smad1) and ALK5 (Smad2) signaling.

Androgen deprivation therapy as adjuvant/neoadjuvant to radiotherapy for high-risk localised and locally advanced prostate cancer: recent developments

Androgen deprivation therapy (ADT) has traditionally formed the mainstay of treatment for advanced/metastatic prostate cancer (PCa); however, it is now also having an increasingly important role in earlier stages of disease. Indeed, in patients with locally advanced or high-risk localised disease, the addition of neoadjuvant and adjuvant hormone therapy is now considered the standard of care for those men treated with radical radiotherapy. Although luteinising hormone-releasing hormone (LHRH) agonists have been used for many years as ADT, they may be associated with clinical flare and testosterone breakthrough. Newer hormonal agents continue to be developed, such as gonadotropin-releasing hormone antagonists, which reduce testosterone and prostate-specific antigen levels more rapidly than LHRH agonists, without testosterone flare. This review examines ADT use in combination with radiotherapy to improve outcomes in localised or locally advanced disease, and examines some of the latest developments in hormonal therapy for PCa.