Rapid suppression of plasma testosterone levels and tumor growth in the dunning rat model treated with degarelix, a new gonadotropin-releasing hormone antagonist

Therapeutic potential of GNRHR analogs and SRC/FAK inhibitors to counteract tumor growth and metastasis in breast cancer

Breast cancer (BC) is the leading cause of cancer death in women, with hormone-dependent BC accounting for about 80 % of cases, primarily affecting postmenopausal women with gonadotropins, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) elevated. Treatments targeting the gonadotropin-releasing hormone receptor (GnRHR), such as the agonist leuprorelin (LEU) and antagonist degarelix (DEGA), are used for hormone-dependent tumors. While the functional role of gonadotropin receptors in extragonadal tissues remains uncertain, recent studies suggest LH contributes to tumor development and progression. Tumor progression involves reorganization in the actin cytoskeleton, induction of adhesion, and cell migration, driven by proteins such as Src and the focal adhesion kinase (FAK), which are related to invasive behaviors. The overexpression of both protein kinases generates an invasive and metastatic phenotype, then inhibitors targeting Src (PP2) and FAK (FAKi) have been developed to counteract this effect. This study combined GnRH analogs with Src and FAK inhibitors to target BC progression. We found that LH treatment influenced gene expression linked to tumor development. Examining the GnRHR-LEU and GnRHR-DEGA complexes revealed structural differences affecting ligand binding. In an orthotopic tumor model, DEGA reduced tumor growth, while LEU had the opposite effect. Combining DEGA with PP2 or FAKi enhanced tumor inhibition, improving mice survival. These findings provide valuable insights into the essential regulatory role of gonadotropins in genes involved in tumorigenic processes, highlighting the potential of GnRHR antagonists combined with Src or FAK inhibitors as a promising strategy to develop new drugs that interfere with the ability of breast tumor progression.

A 50-year journey in the development of treatment for benign prostatic hyperplasia

Recent research underscores the crucial role of hormone regulation in benign prostatic hyperplasia (BPH) and the therapeutic promise of growth hormone-releasing hormone (GH-RH) antagonists. BPH incidence in aging men doubled over three decades, driven by prostatic enlargement and lower urinary tract symptoms (LUTS). Aging-related changes in GH-RH and luteinizing hormone-releasing hormone (LH-RH) biology promote BPH through hormonal and inflammatory processes. Traditional therapies provide symptomatic relief but often fail to prevent progression. This review explores the 50-year extensive development of LH-RH and GH-RH peptide analogs from discovery to delivery and their potential in BPH treatment. In preclinical studies, GH-RH antagonists reduced prostate volume, improved LUTS, and modulated inflammation mediated by NF-κB and IGF-I. Clinical trials are needed to validate antagonist efficacy and safety. Given BPH's public health impact among the aged, and especially among aging Veterans, integrating GH-RH antagonists into management strategies may offer precision-based therapeutic advancements.

Androgen deprivation therapy exacerbates Alzheimer's-associated cognitive decline via increased brain immune cell infiltration

Androgen deprivation therapy (ADT) for prostate cancer is associated with an increased risk of dementia, including Alzheimer's disease (AD). The mechanistic connection between ADT and AD-related cognitive impairment in patients with prostate cancer remains elusive. We established a clinically relevant prostate cancer-bearing AD mouse model to explore this. Both tumor-bearing and ADT induce complex changes in immune and inflammatory responses in peripheral blood and in the brain. ADT disrupts the integrity of the blood-brain barrier (BBB) and promotes immune cell infiltration into the brain, enhancing neuroinflammation and gliosis without affecting the amyloid plaque load. Moreover, treatment with natalizumab, an FDA-approved drug targeting peripheral immune cell infiltration, reduces neuroinflammation and improves cognitive function in this model. Our study uncovers an inflammatory mechanism, extending beyond amyloid pathology, that underlies ADT-exacerbated cognitive deficits, and suggests natalizumab as a potentially effective treatment in alleviating the detrimental effects of ADT on cognition.

A review of clinical evidence to assess differences in efficacy and safety of luteinizing hormone-releasing hormone (LHRH) agonist (goserelin) and LHRH antagonist (degarelix)

Luteinizing hormone-releasing hormone agonist (LHRH-A), goserelin, and antagonist, degarelix, are both indicated for the treatment of advanced prostate cancer (PCa); however, large comparative trials evaluating their efficacy and safety are lacking. In this review, we assessed the available evidence for both the drugs. Although degarelix achieves an early rapid decline in testosterone (T) and prostate-specific antigen (PSA) levels, median T and PSA levels, in addition to prostate volume and International Prostate Symptom Scores, become comparable with goserelin over the remaining treatment period. Degarelix causes no initial flare, therefore it is recommended in patients with spinal metastases or ureteric obstruction. Goserelin achieves lower PSA, improved time to progression, and better survival outcomes when administered adjunctively to radiotherapy compared with radiotherapy alone, with significant results even over long-term follow-up. The evidence supporting adjuvant degarelix use is limited. Goserelin has better injection site safety, single-step delivery, and an efficient administration schedule compared with degarelix, which has significantly higher injection site reactions and less efficient administration mechanism. There is conflicting evidence about the risk of cardiovascular disease (CVD), and caution is required when using LHRH-A in patients with preexisting CVD. There is considerable long-term evidence for goserelin in patients with advanced PCa, with degarelix being a more recent option. The available comparative evidence of goserelin versus degarelix has several inherent limitations related to study design, sample size, conduct, and statistical analyses, and hence warrants robust prospective trials and long-term follow-up.

The GnRH Antagonist Degarelix Suppresses Gonadotropin Secretion and Pituitary Sensitivity in Midgestation Sheep Fetuses

The specific role of gonadotropin-releasing hormone (GnRH) on brain sexual differentiation remains unclear. To investigate whether gonadotropin and, in turn, testosterone (T) secretion is regulated by GnRH during the critical period for brain differentiation in sheep fetuses, we attempted to selectively suppress pituitary-testicular activation during midgestation with the long-acting GnRH antagonist degarelix. Fetuses received subcutaneous injections of the antagonist or vehicle on day 62 of gestation. After 2 to 3 weeks we examined consequences of the intervention on baseline and GnRH-stimulated plasma luteinizing hormone (LH) and T levels. In addition, we measured the effect of degarelix-treatment on messenger RNA (mRNA) expression for the pituitary gonadotropins and key gonadal steroidogenic enzymes. Baseline and GnRH-stimulated plasma LH levels were significantly suppressed in degarelix-treated male and female fetuses compared to control values. Similarly, T concentrations were suppressed in degarelix-treated males. The percentage of LHβ-immunoreactive cells colocalizing c-fos was significantly reduced by degarelix treatment indicating that pituitary sensitivity was inhibited. Degarelix treatment also led to the significant suppression of mRNA expression coding for the pituitary gonadotropin subunits and for the gonadal enzymes involved in androgen synthesis. These findings demonstrate that pharmacologic inhibition of GnRH early in gestation results in suppression of LH secretion and deficits in the plasma T levels of male lamb fetuses. We conclude that GnRH signaling plays a pivotal role for regulating T exposure during the critical period of sheep gestation when the brain is masculinized. Thus, disturbance to gonadotropin secretion during this phase of gestation could have long-term consequence on adult sexual behaviors and fertility.

Endothelial dysfunction after androgen deprivation therapy and the possible underlying mechanisms

INTRODUCTION

Androgen deprivation therapy (ADT) is a key treatment modality in the management of prostate cancer (PCa), especially for patients with metastatic disease. Increasing evidences suggest that patients who received ADT have increased incidence of diabetes, myocardial infarction, stroke, and even mortality. It is important to understand the pathophysiological mechanisms on how ADT increases cardiovascular risk and induces cardiovascular events, which would provide important information for potential implementation of preventive measures.

METHODS

Twenty-six 12-week-old male SD rats were divided into four groups for different types of ADTs including: the bilateral orchidectomy group (Orx), LHRH agonist group (leuprolide), LHRH antagonist group (degarelix), and control group. After treated with drug or adjuvant injection every 3 weeks for 24 weeks, all rats were sacrificed and total blood were collected. Aorta, renal arteries, and kidney were preserved for functional assay, immunohistochemistry, western blot, and quantitative reverse-transcription polymerase chain reaction.

RESULTS

In vascular reactivity assays, aorta, intrarenal, and coronary arteries of all three ADT groups showed endothelial dysfunction. AT1R and related molecules at protein and messenger RNA (mRNA) level were tested, and AT1R pathway was shown to be activated and played a role in endothelial dysfunction. Both ACE and AT1R mRNA levels were doubled in the aorta in the leuprolide group while Orx and degarelix groups showed upregulation of AT1R in the kidney tissues. By immunohistochemistry, our result showed higher expression of AT1R in the intrarenal arteries of leuprolide and degarelix groups. The role of reactive oxygen species in endothelial dysfunction was confirmed by DHE fluorescence, nitrotyrosine overexpression, and upregulation of NOX2 in the different ADT treatment groups.

CONCLUSION

ADT causes endothelial dysfunction in male rats. GnRH receptor agonist compared to GnRH receptor antagonist, showed more impairment of endothelial function in the aorta and intrarenal arteries. Such change might be associated with upregulation and activation of AngII-AT1R-NOX2 induced oxidative stress in the vasculature. These results help to explain the different cardiovascular risks and outcomes related to different modalities of ADT treatment.

Cardiac and Brainstem Neuroinflammatory Pathways Account for Androgenic Incitement of Cardiovascular and Autonomic Manifestations in Endotoxic Male Rats

ABSTRACT

Inconsistent reports are available on the role of testosterone in end-organ damage caused by endotoxemia. Here, pharmacologic, surgical, and molecular studies were employed to assess the testosterone modulation of cardiovascular, autonomic, and peripheral and central inflammatory derangements caused by endotoxemia. Studies were performed in conscious male rats preinstrumented with femoral indwelling catheters for the measurement of blood pressure and subjected to castration or pharmacologic interventions that interrupt the biosynthetic cascade of testosterone. Compared with the effects of lipopolysaccharide (10 mg/kg intravenously) in sham operated rats, 2-week castration reduced the lipopolysaccharide-evoked (1) falls in blood pressure, (2) decreases in time- and frequency-domain indices of heart rate variability, (3) shifts in spectral measures of cardiac sympathovagal balance toward parasympathetic dominance, and (4) increases in protein expressions of toll-like receptor-4 and monocyte chemoattractant protein-1 in heart and medullary neurons of the nucleus tractus solitarius and rostral ventrolateral medulla. While the ameliorating actions of castration on endotoxic cardiovascular manifestations were maintained after testosterone replacement, the concomitant inflammatory signals were restored to near-sham levels. The favorable influences of castration on inflammatory and cardiovascular abnormalities of endotoxemia were replicated in intact rats pretreated with degarelix (gonadotropin-releasing hormone receptor blocker) or finasteride (5α-reductase inhibitor) but not formestane (aromatase inhibitor). The data signifies the importance of androgens and its biosynthetic enzymes in cardiovascular and autonomic insults induced by the endotoxic inflammatory response. Clinically, the interruption of testosterone biosynthesis could offer a potential strategy for endotoxemia management.

Androgenic modulation of arterial baroreceptor dysfunction and neuroinflammation in endotoxic male rats

Autonomic neuropathy contributes to cardiovascular derangements induced by endotoxemia. In this communication, we tested the hypothesis that androgenic hormones improve arterial baroreflex dysfunction and predisposing neuroinflammatory response caused by endotoxemia in male rats. Baroreflex curves relating changes in heart rate to increases or decreases in blood pressure evoked by phenylephrine (PE) and sodium nitroprusside (SNP), respectively, were constructed in conscious sham-operated, castrated, and testosterone-replaced castrated rats treated with or without lipopolysaccharide (LPS, 10 mg/kg i.v.). Slopes of baroreflex curves were taken as measures of baroreflex sensitivity (BRS). In sham rats, LPS significantly reduced reflex bradycardia (BRSPE) and tachycardia (BRSSNP) and increased immunohistochemical expression of nuclear factor kappa B (NFκB) in heart and brainstem neurons of nucleus tractus solitarius (NTS) and rostral ventrolateral medulla (RVLM). The baroreflex depressant effect of LPS was maintained in castrated rats despite the remarkably attenuated inflammatory response. Testosterone replacement of castrated rats counteracted LPS-evoked BRSPE, but not BRSSNP, depression and increased cardiac, but not neuronal, NFκB expression. We also evaluated whether LPS responses could be affected following pharmacologic inhibition of androgenic biosynthetic pathways. Whereas none of LPS effects were altered in rats pretreated with formestane (aromatase inhibitor) or finasteride (5α-reductase inhibitor), the LPS-evoked BRSPE, but not BRSSNP, depression and cardiac and neuronal inflammation disappeared in rats pretreated with degarelix (gonadotropin-releasing hormone receptor blocker). Overall, despite the seemingly provocative role for the hypothalamic-pituitary-gonadal axis in the neuroinflammatory and baroreflex depressant effects of LPS, testosterone appears to distinctly modulate the two LPS effects.

Sexual Motivation and Sexual Reward in Male Rats are Attenuated by the Gonadotropin-Releasing Hormone Receptor Antagonist Degarelix

BACKGROUND

Preclinical studies that have examined the effects of androgen deprivation therapies (ADTs) on sexual outcomes have either relied on a surgical castration model of ADTs or have largely focused on consummatory sexual behaviors.

AIM

The aim of this study was to examine the effects of a single administration of the gonadotropin-releasing hormone receptor antagonist, degarelix, on sexual incentive motivation (SIM), sexual reward, consummatory sexual behaviors, anxiety-like behavior, and androgen receptor signaling in male rats, and to determine if sexual stimulation attenuates the effects of degarelix on SIM.

METHODS

Male rats were treated with degarelix, or vehicle, and half of the rats in each condition were briefly exposed to a sexually receptive female immediately before SIM trials (experiment 1). Rats treated with degarelix or vehicle were also given a sex-conditioned place preference test (experiment 2A), weekly mating tests (experiment 2B), and an elevated zero maze test (experiment 3). Androgen-sensitive tissues were excised upon completion of testing.

OUTCOMES

SIM was indicated by the percentage of time spent near a sexually receptive female on the SIM tests. The percentage of time spent in the chamber of a conditioned place preference maze associated with sexual experience was indicative of sexual reward. The percentage of trials in which a mount, intromission, and ejaculation occurred was indicative of copulatory ability. Sexual performance was characterized by the average latencies to first exhibit these behaviors, as well as the average frequency of these behaviors. Anxiety-like behavior was indicated by the percentage of time in the open zones of an elevated zero maze. Relative weights of the seminal vesicles and bulbourethral glands were used to quantify androgen activity.

RESULTS

Rats treated with degarelix exhibited lower levels of SIM. In rats treated with degarelix, contact with a female immediately before SIM testing increased activity, but not SIM. Treatment with degarelix reduced the rewarding aspects of sexual behavior, as well as most aspects of copulatory ability and sexual performance. Degarelix treatment reduced androgen signaling, but did not impact anxiety-like behavior.

CLINICAL IMPLICATIONS

The behavioral side effects associated with the use of degarelix may be restricted to sexual behaviors.

STRENGTHS & LIMITATIONS

Strengths include the objective measurement of sexual behaviors. The study is limited in that only one ADT was examined.

CONCLUSION

These findings serve as an extension of previous preclinical studies as they indicate that gonadotropin-releasing hormone receptor antagonism in male rats also attenuates sexual motivation and sexual reward, in addition to copulatory ability and sexual performance. Hawley WR, Kapp LE, Green PA, et al. Sexual Motivation and Reward in Male Rats are Attenuated by the Gonadotropin-Releasing Hormone Receptor Antagonist Degarelix. J Sex Med 2021;18:240-255.

Plumbagin improves the efficacy of androgen deprivation therapy in prostate cancer: A pre-clinical study

BACKGROUND

Plumbagin is a candidate drug for the treatment of prostate cancer. Previous observations indicated that it may improve the efficacy of androgen deprivation therapy (ADT). This study evaluates the effectiveness of treatment with combinations of plumbagin and alternative strategies for ADT in mouse models of prostate cancer to support its clinical use.

METHODS

Plumbagin was administered per oral in a new sesame oil formulation. Standard toxicology studies were performed in rats. For tumor growth studies, mouse prostate cancer cell spheroids were placed on top of grafted prostate tissue in a dorsal chamber and allowed to form tumors. Mice were separated in various treatment groups and tumor size was measured over time by intra-vital microscopy. Survival studies were done in mice after injection of prostate cancer cells in the prostate of male animals. Androgen receptor (AR) levels were analyzed by Western blot from prostate cancer cells treated with plumbagin.

RESULTS

Plumbagin caused a decrease in AR levels in vitro. In mice, plumbagin at 1 mg/kg in sesame oil displayed low toxicity and caused a 50% tumor regression when combined with castration. The combination of plumbagin with various forms of chemical ADT including treatment with a GnRH receptor agonist, a GnRH receptor antagonist, or CYP17A1 inhibitors, outperformed ADT alone, increasing mouse survival compared to the standard regimen of castration alone. In contrast, the combination of plumbagin with AR antagonists, such as bicalutamide and enzalutamide, showed no improvement over AR antagonists alone. Thus, plumbagin is effective in combination with drugs that prevent the synthesis of testosterone or its conversion to dihydrotestosterone, but not with drugs that bind to AR.

CONCLUSION

Plumbagin significantly improves the effect of ADT drugs currently used in the clinic, with few side effects in mice.

An efficient synthesis of deuterium-labeled degarelix acetate, a third-generation gonadotropin-releasing hormone receptor antagonist

Degarelix acetate, a third-generation gonadotropin-releasing hormone receptor antagonist, shows great potential in the treatment of many androgen-related diseases. To support clinical studies of degarelix acetate, deuterium-labeled degarelix is highly desired for use as an internal standard. Using D₂ O/D₃ PO₄ as a deuterium source, 2-amino-3-(naphthalen-2-yl)propanoic acid was converted to deuterated degarelix acetate in 13 steps and in 14% overall yield.

Stress alters the expression of cancer-related genes in the prostate

Background

Prostate cancer is a major contributor to mortality worldwide, and significant efforts are being undertaken to decipher specific cellular and molecular pathways underlying the disease. Chronic stress is known to suppress reproductive function and promote tumor progression in several cancer models, but our understanding of the mechanisms through which stress contributes to cancer development and progression is incomplete. We therefore examined the relationship between stress, modulation of the gonadotropin-releasing hormone (GnRH) system, and changes in the expression of cancer-related genes in the rat prostate.

Methods

Adult male rats were acutely or repeatedly exposed to restraint stress, and compared to unstressed controls and groups that were allowed 14 days of recovery from the stress. Prostate tissue was collected and frozen for gene expression analyses by PCR array before the rats were transcardially perfused; and brain tissues harvested and immunohistochemically stained for Fos to determine neuronal activation.

Results

Acute stress elevated Fos expression in the paraventricular nucleus of the hypothalamus (PVH), an effect that habituated with repeated stress exposure. Data from the PCR arrays showed that repeated stress significantly increases the transcript levels of several genes associated with cellular proliferation, including proto-oncogenes. Data from another array platform showed that both acute and repeated stress can induce significant changes in metastatic gene expression. The functional diversity of genes with altered expression, which includes transcription factors, growth factor receptors, apoptotic genes, and extracellular matrix components, suggests that stress is able to induce aberrant changes in pathways that are deregulated in prostate cancer.

Conclusions

Our findings further support the notion that stress can affect cancer outcomes, perhaps by interfering with neuroendocrine mechanisms involved in the control of reproduction.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3635-4) contains supplementary material, which is available to authorized users.

Discovery of LHRH and development of LHRH analogs for prostate cancer treatment

The discovery, isolation, elucidation of structure, synthesis, and initial testing of the neuropeptide hypothalamic luteinizing hormone-releasing hormone (LHRH), which regulates reproduction, is briefly described. The design, synthesis, and experimental and clinical testing of agonistic analogs of LHRH is extensively reviewed focusing on the development of new methods for the treatment of prostate cancer. Subsequent development of antagonistic analogs of LHRH is then faithfully recounted with special emphasis on therapy of prostate cancer and BPH. The concepts of targeted therapy to peptide receptors on tumors are re-examined and the development of the cytotoxic analogs of LHRH and their status is reviewed. The endeavor to develop better therapies for prostate cancer, based on LHRH analogs, guided much of our work.

GNRH-agonist or antagonist in the treatment of prostate cancer: a comparision based on oncological results

On the basis of the trials available, are we ready to consider GnRH antagonists better than agonists? Is there a population of patients who may benefit from antagonists more than agonists?We specifically focused our analysis on the significance of oncological results obtained in phase III trials directly comparing Degarelix with GnRH agonists. Oncological results were evaluated only in 1 trial (CS21) with some subanalysis and they were not the primary endpoints of the study. The follow-up duration was 364 days, and therefore, the number of events (all causes deaths and prostate cancer (PC), Prostate Specific Antigen (PSA), Hazard ratio (HR)-related deaths) was very low in both groups and this aspect strongly reduces the significance of overall survival evaluation. In our opinion, the CS21A open-label extension does not consent to obtain useful clinical data and the design of the study loses the possibility to have a longer randomized comparison between degarelix and agonist. Moreover, the fact that the crossover from leuprolide to degarelix was pre-defined at 12 months and not at agonist failure does not allow to gather data also on the effect of sequential treatment.The answer to the question whether we are ready to consider antagonists better than agonists, based on oncological results, is probably no. We have data in terms of testosterone suppression and PSA control rather than overall survival or clinical progression free survival. A PSA progression-free survival is a secondary endpoint that in our opinion is not sufficient. Large prospective comparative trials with long-term follow-up are needed to clarify this critical clinical question.

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.

Evolution of androgen receptor targeted therapy for advanced prostate cancer

The discovery of androgen dependence in prostate cancer in 1941 by Huggins and colleagues has remained the backbone for the treatment of this disease. However, although many patients initially respond to androgen depletion therapy, they almost invariably relapse and develop resistance with transition of the disease to a castration-resistant state. Over the past decade, the better understanding of the mechanisms that drive resistance to castration has led to the development of next-generation androgen receptor targeting agents such as abiraterone acetate and enzalutamide. This Review aims to revisit the discovery and evolution of androgen receptor targeting therapeutics for the treatment of advanced-stage prostate cancer over the years and to discuss the upcoming future and challenges in the treatment of this common cancer.

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.

Degarelix versus goserelin (+ antiandrogen flare protection) in the relief of lower urinary tract symptoms secondary to prostate cancer: results from a phase IIIb study (NCT00831233)

INTRODUCTION

No studies to date have assessed the efficacy/tolerability of degarelix in the relief of lower urinary tract symptoms (LUTS) secondary to prostate cancer (PrCa).

METHODS

Patients were randomised to degarelix 240/80 mg or goserelin 3.6 mg + bicalutamide flare protection (G+B); both treatments were administered for 3 months. The primary endpoint was change in International Prostate Symptom Score (IPSS) at week 12 compared with baseline.

RESULTS

This study was stopped early due to recruitment difficulties. 40 patients received treatment (degarelix n = 27; G+B n = 13); most had locally advanced disease and were highly symptomatic. Degarelix was non-inferior to G+B in reducing IPSS at week 12 in the full analysis set (p = 0.20); the significantly larger IPSS reduction in the per-protocol analysis (p = 0.04) was suggestive of superior reductions with degarelix. Significantly more degarelix patients had improved quality of life (IPSS question) at week 12 (85 vs. 46%; p = 0.01). Mean prostate size reductions at week 12 were 42 versus 25% for patients receiving degarelix versus G+B, respectively (p = 0.04; post hoc analysis). Most adverse events were mild/moderate; more degarelix patients experienced injection site reactions whereas more G+B patients had urinary tract infections/cystitis.

CONCLUSION

In 40 men with predominantly locally advanced PrCa and highly symptomatic LUTS, degarelix was at least non-inferior to G+B in reducing IPSS at week 12.

New Agonist- and Antagonist-Based Treatment Approaches for Advanced Prostate Cancer

Increased understanding of prostate cancer biology has led to new treatment strategies and promising new agents for treating prostate cancer, in particular peptide-based agonists and antagonists. In this review article, new therapy modalities and potential approaches for the treatment of advanced prostate cancer are discussed, including agonists and antagonists of luteinizing hormone-releasing hormone, antagonists of bombesin/gastrin-releasing peptide, and growth hormone-releasing hormone and somatostatin analogues. Though the prognosis of patients with prostate cancer is much improved by some of these treatment approaches, including combination treatment methods, extensive side-effects are still reported. These include sexual dysfunction, functional lesions of the liver and renal system, osteoporosis, anaemia and diarrhoea. Future studies should focus on new treatment agents and treatment approaches that can eliminate side-effects and improve quality of life in patients with prostate cancer on the basis of potent treatment efficacy.

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.

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.

Metabolite profiles of degarelix, a new gonadotropin-releasing hormone receptor antagonist, in rat, dog, and monkey

Degarelix is a novel competitive gonadotropin-releasing hormone receptor blocker (antagonist). In this study, the nonclinical metabolism and excretion of degarelix was investigated in Sprague-Dawley rat, beagle dog, and cynomolgus monkey. Degarelix was found to be stable when incubated in microsomes and cryopreserved hepatocytes from animal liver tissue. Absorption, distribution, metabolism, and excretion studies in male rat, dog, and monkey showed that after a subcutaneous dose of tritium-labeled degarelix, the peptide was rapidly absorbed with C(max) in plasma of 1 to 2 h. The predominant route of excretion was via the kidneys and the bile. In rat and dog, most of the degarelix dose was eliminated within 48 h via urine and feces in equal amounts (40-50% in each matrix), whereas in monkey the major route of excretion was fecal (50%) and renal (22%). In plasma and urine samples from all three species, mainly intact degarelix was detected. In bile and feces samples from rats and dogs, the same truncated peptides of the parent decapeptide were detected. The major metabolites identified represented the N-terminal tetrapeptide, the pentapeptide, and the heptapeptide. From the animal studies, it could be concluded that degarelix is subject to common peptidic degradation in the liver and bile and is fully excreted via metabolic and biliary (as metabolites and parent compound) and urinary (mainly as parent compound) pathways. Systemic exposure to metabolic products seems to be low.

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

Androgen deprivation therapy (ADT) is the main treatment approach in advanced prostate cancer and in recent years has primarily involved the use of gonadotropin-releasing hormone (GnRH) agonists. However, despite their efficacy, GnRH agonists have several drawbacks associated with their mode of action. These include an initial testosterone surge and testosterone microsurges on repeat administration. GnRH antagonists provide an alternative approach to ADT with a more direct mode of action that involves immediate blockade of GnRH receptors. Antagonists produce a more rapid suppression of testosterone (and prostate-specific antigen [PSA]) without a testosterone surge or microsurges and appear to offer an effective and well tolerated option for the hormonal treatment of prostate cancer. Comparisons with GnRH agonists have shown GnRH antagonists to be at least as effective in achieving and maintaining castrate testosterone levels in patients with prostate cancer. Furthermore, with antagonists, the lack of an initial testosterone surge (which may cause clinical flare) may allow more rapid relief of symptoms related to prostate cancer, avoid the need for concomitant antiandrogens to prevent clinical flare (so avoiding any antiandrogen-associated adverse events) and allow GnRH antagonist use in patients with high tumour burden and/or acute problems such as spinal cord compression. Although several antagonists have been investigated, only degarelix and abarelix are currently available for clinical use in prostate cancer. Currently, degarelix is the most extensively studied and widely available agent in this class. Degarelix is one of a newer generation of antagonists which, in a comprehensive and ongoing clinical development programme, has been shown to provide rapid, profound and sustained testosterone suppression without the systemic allergic reactions associated with earlier antagonists. This review examines the currently available data on GnRH antagonists in prostate cancer.

[Prostate cancer 2010. Therapeutic innovations]

During the annual congress of the SFRO, a symposium, on "Therapeutic innovations", described some of the burning questions in the treatment of prostate cancer. What is the best technique to perform radiation dose escalation, brachytherapy or Intensity modulated radiotherapy? Rational has been highlighted for both techniques, but without a prospective comparative trial, no definitive answer could be given today. The role of neo-adjuvant hormonal treatment, before surgery or radiotherapy is still discussed, particularly in the area of LH-RH antagonists which have a rapid and profound anti-hormonal effect. At least, the salvage treatment for biochemical relapse after external beam irradiation has been discussed: surgery, cryotherapy, and High-Intensity focalised ultrasons and the timing of hormonal treatment.

Degarelix, a novel GnRH antagonist, causes minimal histamine release compared with cetrorelix, abarelix and ganirelix in an ex vivo model of human skin samples

AIMS

Early studies on gonadotrophin-releasing hormone (GnRH) antagonists pointed out histamine-mediated anaphylactic reactions as a potential adverse effect of these drug candidates. In this study we have compared the histamine-releasing potential of four approved and marketed antagonists, degarelix, cetrorelix, abarelix and ganirelix in an ex vivo model of human skin samples.

METHODS

Human skin samples were obtained during cosmetic plastic surgery and kept in oxygenated saline solution. The samples were incubated either without or at different concentrations of the antagonists (3, 30 or 300 µg ml(-1) for all, except for ganirelix 1, 10 or 100 µg ml(-1) ). The drug-induced effect was expressed as the increase relative to basal release. The histamine-releasing capacity of the skin was verified by a universal histamine releaser, compound 40/80.

RESULTS

Degarelix had no significant effect on basal histamine release in the 3 to 300 µg ml(-1) concentration range. The effect of ganirelix was moderate causing a nonsignificant increase of 81 ± 27% at the 100 µg ml(-1) concentration. At 30 and 300 µg ml(-1) concentrations abarelix (143 ± 29% and 362 ± 58%, respectively, P < 0.05) and cetrorelix (228 ± 111% and 279 ± 46%, respectively, P < 0.05) caused significantly increased histamine release.

CONCLUSIONS

In this ex vivo human skin model, degarelix displayed the lowest capacity to release histamine followed by ganirelix, abarelix and cetrorelix. These findings may provide indirect hints as to the relative likelihood of systemic anaphylactic reactions in clinical settings.

Degarelix: a gonadotropin-releasing hormone antagonist for the management of prostate cancer

BACKGROUND

Prostate cancer is the most commonly diagnosed cancer among men. Treatment can include surgery, radiation, chemotherapy, or hormonal manipulation. Gonadotropin-releasing hormone (GnRH) analogues are used to manage prostate cancer by desensitizing the stimulus to synthesize and release gonadotropins, such as luteinizing hormone (LH), which stimulate the synthesis and release of androgens, in turn stimulating the growth of prostate cancer cells. Although effective, these agents have limitations, such as a flare-up of cancer symptoms within the first 2 weeks of starting the drug.

OBJECTIVE

This article reviews the pharmacology, pharmacokinetic and pharmacodynamic characteristics, and clinical data available on the newly approved drug degarelix for use in treating prostate cancer.

METHODS

A search of the medical literature was performed in January 2009 with the databases MEDLINE and EMBASE (1950-present) and International Pharmaceutical Abstracts (1970-November 2008) using the terms degarelix and FE200486; follow-up searches using the same strategy were conducted in May 2009 and August 2009. Additional sources were identified by scanning available references and online journals and textbooks.

RESULTS

GnRH antagonists, such as degarelix, offer clinicians another means to reduce the level of circulating androgens and limit this growth stimulus directed at malignant prostate tissue. Degarelix has been shown in animal studies to antagonize GnRH receptors in the pituitary gland, resulting in a significant reduction in circulating LH and a subsequent decrease in the synthesis of testosterone. Pharmacokinetic analysis suggests that upon subcutaneous administration, degarelix forms a gel depot, from which the drug then distributes to the rest of the body in a first-order manner. A Phase II study of the effect of degarelix in 187 men with prostate cancer found a loading dose of 240 mg to be not significantly better than 200 mg in reducing serum testosterone concentrations to < or =0.5 ng/mL within 3 days of dosing (200 mg, 88%; 240 mg, 92%). This difference in percentage of patients with testosterone suppression became statistically significant when measured again 1 month into the study (200 mg, 86%; 240 mg, 95%; P = 0.048). Evaluation of 80-, 120-, and 160-mg maintenance doses found all doses effective in maintaining suppression of testosterone, LH, and prostate-specific antigen (PSA); only minor differences were observed during the study period. In a Phase III study of 610 patients with prostate cancer, a loading dose of degarelix 240 mg SC followed by monthly maintenance doses of either 80 or 160 mg was compared with monthly doses of leuprolide 7.5 mg IM. Degarelix was found to be at least as effective as leuprolide in the ability to suppress serum testosterone to < or =0.5 ng/mL for up to 1 year (degarelix response rate, 80 mg, 97.2%; 95% CI, 93.5%-98.8%; degarelix 160 mg, 98.3%; 95% CI, 94.8%-99.4%; leuprolide response rate, 96.4%; 95% CI, 92.5%-98.2%). Other studies investigating various doses and schedules of degarelix have also been conducted. Adverse effects of degarelix in clinical trials were mild and relatively uncommon and included flushing reactions, injection-site pain, weight gain, and increases in serum transaminase levels.

CONCLUSIONS

Degarelix offers another option for chemical castration to reduce the androgenic growth stimulus on prostate cancer cells. The manufacturer of degarelix recommends a loading dose of 240 mg SC followed by the first monthly maintenance dose of 80 mg 28 days later. Serum testosterone and PSA concentrations must be obtained to monitor the response during treatment with degarelix.

Degarelix

Degarelix is a gonadotropin-releasing hormone (GnRH) receptor antagonist that, in common with GnRH receptor agonists (e.g. leuprolide, goserelin and triptorelin), is indicated for use as an androgen-deprivation therapy in patients with advanced prostate cancer. In 1-year, randomized, open-label, phase II or III trials in patients with all stages of prostate cancer, subcutaneous degarelix was associated with rapid, profound and sustained suppression of serum testosterone and prostate-specific antigen (PSA), without evidence of testosterone surges or microsurges. In the phase III trial, degarelix (240 mg initially followed by 80 mg every 28 days) was considered to be effective and noninferior to intramuscular leuprolide (7.5 mg every 28 days) with regard to inducing and maintaining suppression of serum testosterone to castrate levels (i.e. <or=0.5 ng/mL). Degarelix induced testosterone suppression more rapidly than leuprolide. Median serum testosterone levels of <or=0.5 ng/mL were achieved by day 3 in degarelix recipients, but not until day 28 in leuprolide recipients. PSA suppression was also more rapid with degarelix than with leuprolide, with significant between-group differences in serum PSA levels favouring degarelix at 14 and 28 days. Degarelix treatment for 1 year was generally well tolerated; the adverse events reported were mostly related to subcutaneous drug administration (i.e. injection-site reactions) and hormonal androgen deprivation (e.g. hot flushes).

Degarelix: a novel gonadotropin-releasing hormone blocker for the treatment of prostate cancer

Androgen deprivation therapy with gonadotropin releasing-hormone (GnRH) receptor agonists provides the mainstay of endocrine treatment for advanced prostate cancer. Although effective, GnRH agonists induce an initial testosterone surge, which can cause painful and potentially dangerous clinical flare. Degarelix is a novel GnRH receptor blocker that provides immediate, profound and sustained testosterone reduction, without an initial surge. In a Phase III trial, degarelix and leuprolide showed similar long-term efficacy in maintaining testosterone levels of 0.5 ng/ml or less over 1 year, and induced significantly faster testosterone and prostate-specific antigen suppression. Degarelix was well tolerated; the most common side effects were mild/moderate injection-site reactions and hot flashes. Findings to date suggest that degarelix may make an important contribution to the treatment of prostate cancer.

Will GnRH antagonists improve prostate cancer treatment?

Androgen ablation forms a basis for treating prostate cancer and is achieved either by surgical castration, or pharmacologically using oestrogens, anti-androgens and/or gonadotropin-releasing hormone (GnRH) analogues. GnRH antagonists (or blockers) offer a new means of treatment by directly blocking GnRH receptors. Advantages of GnRH antagonists include lack of the initial stimulation of gonadotropin and testosterone production, lack of gonadotropin microsurges and sustained follicle-stimulating hormone suppression; disadvantages include increased histamine release. This review discusses advantages and disadvantages of the GnRH antagonists currently in development, in light of receptor physiology and pre-clinical and clinical data. Comparative clinical trials will ultimately establish their efficacy in comparison to other pharmacotherapies. Therefore, continuing development and refinement is needed to improve prostate cancer treatment.

Management of advanced prostate cancer: can we improve on androgen deprivation therapy?

Gonadotrophin-releasing hormone (GnRH) agonists are currently the mainstay in the management of advanced prostate cancer. Used either as monotherapy or combined with antiandrogens, GnRH agonists suppress serum testosterone levels and thus slow the growth of the tumour cells that depend on testosterone for growth. GnRH agonists have largely replaced orchidectomy in the management of advanced prostate cancer, because patients are reluctant to undergo surgical castration. However, can we do better in androgen-deprivation therapy? There is some evidence to suggest that GnRH agonists do not achieve the level of testosterone suppression attained with orchidectomy, or as rapidly, factors which could be expected to affect overall survival. Together, these observations highlight the need to develop newer agents that can achieve rapid, profound and sustained testosterone suppression, equivalent to that with orchidectomy. Preliminary data for the GnRH blocker, degarelix, suggest that this new agent might overcome the shortcomings associated with GnRH agonists. Further clinical data are therefore awaited with much interest.

New treatment approaches for prostate cancer based on peptide analogues

OBJECTIVES

New therapy modalities for the treatment of advanced prostate cancer based on peptide analogues are reviewed.

RESULTS

Agonists and antagonists of luteinising hormone-releasing hormone (LHRH) lead to androgen deprivation, but direct effects on tumours may also play a role. Radiolabeled somatostatin analogues can be targeted to tumours expressing receptors for somatostatin and have been successfully applied for the localization of these tumours. Tumoural LHRH, growth hormone-releasing hormone (GHRH), and bombesin/gastrin-releasing peptide (BN/GRP) and their receptors appear to be involved in the proliferation of prostate cancer. On the basis of the recent advances in the understanding of the role of neuropeptides in tumour growth and progression, new therapeutic modalities are being developed that are based on antagonists of GHRH and of BN/GRP, which inhibit growth factors or their receptors. Another promising approach for the therapy of prostate cancer consists of the use of cytotoxic analogues of LHRH, bombesin, and somatostatin, which can be targeted to receptors for these peptides in prostate cancers and their metastases.

CONCLUSIONS

New promising forms of hormone therapy and targeted chemotherapy may improve therapy of advanced stage prostate cancer.

Luteinising hormone-releasing hormone antagonists in prostate cancer therapy

The introduction of androgen blockade therapy using luteinising hormone-releasing hormone (LHRH)/gonadotropin-releasing hormone analogues alone or in combination with non-steroidal antiandrogens has a major impact in both survival and quality of life of patients with locally advanced and metastatic prostate cancer. The effect of LHRH agonists is based on the continuous binding to the LHRH receptor (LHRH-R) on the gonadotrope cells of the pituitary, which although initially stimulate LH release, consequently downregulates the LHRH-R, thereby suppressing serum LH, testosterone levels and 5alpha-dihydrotestosterone levels. Because this initial surge of LH and testosterone can cause adverse consequences in these patients (the so-called flare-up symptoms), immediate inhibition of LH release and testosterone production is desirable and this can be achieved with the use of the LHRH antagonists. In addition, there exist data to support a direct anticancer effect of LHRH antagonists on prostate cancer cells. This review summarises the potential clinical use of the LHRH antagonists in prostate cancer patients.