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Background: Androgen deprivation therapy (ADT) is the foundational treatment for metastatic prostate cancer (PCa). Androgen receptor (AR) axis-targeted therapies are a new standard of care for advanced PCa. Although these agents have significantly improved patient survival, the suppression of testosterone is associated with an increased risk of cardiometabolic syndrome. This highlights the urgency of multidisciplinary efforts to address the cardiometabolic risk of anticancer treatment in men with PCa. Methods: Two professional organizations invited five urologists, five clinical oncologists, and two cardiologists to form a consensus panel. They reviewed the relevant literature obtained by searching PubMed for the publication period from April 2013 to April 2023, to address three discussion areas: (i) baseline assessment and screening for risk factors in PCa patients before the initiation of ADT and AR axis-targeted therapies; (ii) follow-up and management of cardiometabolic complications; and (iii) selection of ADT agents among highrisk patients. The panel convened four meetings to discuss and draft consensus statements using a modified Delphi method. Each drafted statement was anonymously voted on by every panelist. Results: The panel reached a consensus on 18 statements based on recent evidence and expert insights. Conclusion: These consensus statements serve as a practical recommendation for clinicians in Hong Kong, and possibly the Asia-Pacific region, in the management of cardiometabolic toxicities of ADT or AR axis-targeted therapies in men with PCa. [ABSTRACT FROM AUTHOR]

BackgroundAndrogen deprivation therapy (ADT) is the foundational treatment for metastatic prostate cancer (PCa). Androgen receptor (AR) axis-targeted therapies are a new standard of care for advanced PCa. Although these agents have significantly improved patient survival, the suppression of testosterone is associated with an increased risk of cardiometabolic syndrome. This highlights the urgency of multidisciplinary efforts to address the cardiometabolic risk of anticancer treatment in men with PCa.MethodsTwo professional organizations invited five urologists, five clinical oncologists, and two cardiologists to form a consensus panel. They reviewed the relevant literature obtained by searching PubMed for the publication period from April 2013 to April 2023, to address three discussion areas: (i) baseline assessment and screening for risk factors in PCa patients before the initiation of ADT and AR axis-targeted therapies; (ii) follow-up and management of cardiometabolic complications; and (iii) selection of ADT agents among high-risk patients. The panel convened four meetings to discuss and draft consensus statements using a modified Delphi method. Each drafted statement was anonymously voted on by every panelist.ResultsThe panel reached a consensus on 18 statements based on recent evidence and expert insights.ConclusionThese consensus statements serve as a practical recommendation for clinicians in Hong Kong, and possibly the Asia-Pacific region, in the management of cardiometabolic toxicities of ADT or AR axis-targeted therapies in men with PCa.

One of the main objectives of peptide drug design is the improvement of peptide pharmacokinetics with maintaining biological activity, which can be achieved by the complex modifications of the primary structure of the peptides. However, these changes often lead to the formation of peculiar impurities in the peptide drugs and their metabolites, which require the development of advanced analytical methods to properly assess their content. Here, we investigated the degradation of the potent long‐acting GnRH antagonist degarelix in various biologic media by the tailor‐made HPLC method, which allows precise determination of 5‐Aph(Hyd)‐degarelix isomer, an impurity found in the degarelix active pharmaceutical ingredient (API) during its manufacturing. Unexpectedly, we discovered a rapid and irreversible conversion of degarelix API into the corresponding hydantoin isomer in serum, suggesting that this impurity can be also a potential drug metabolite in vivo. This finding underlines the importance of the development of more accurate and performing analytical techniques to correctly characterize the chemical composition of the manufactured drugs and their behavior under physiological conditions. [ABSTRACT FROM AUTHOR]

Abstract One of the main objectives of peptide drug design is the improvement of peptide pharmacokinetics with maintaining biological activity, which can be achieved by the complex modifications of the primary structure of the peptides. However, these changes often lead to the formation of peculiar impurities in the peptide drugs and their metabolites, which require the development of advanced analytical methods to properly assess their content. Here, we investigated the degradation of the potent long‐acting GnRH antagonist degarelix in various biologic media by the tailor‐made HPLC method, which allows precise determination of 5‐Aph(Hyd)‐degarelix isomer, an impurity found in the degarelix active pharmaceutical ingredient (API) during its manufacturing. Unexpectedly, we discovered a rapid and irreversible conversion of degarelix API into the corresponding hydantoin isomer in serum, suggesting that this impurity can be also a potential drug metabolite in vivo. This finding underlines the importance of the development of more accurate and performing analytical techniques to correctly characterize the chemical composition of the manufactured drugs and their behavior under physiological conditions.

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.

Context: As patients are now living with prostate cancer for longer, the long-term impact of hormonal treatment on bone health is an increasingly debated subject. Objective: To characterize the changes in bone mineral density (BMD) and bone turnover markers after degarelix administration in prostate cancer patients without bone metastases. To explore the predictive role of body composition on treatment induced bone loss. Methods: BMD and body composition (lean body mass, fat body mass, and appendicular mass index [ALMI]) were assessed by dual X-ray absorptiometry on study entry and after 12 months of degarelix therapy. Alkaline phosphate (ALP) and C-terminal telopeptide of type I collagen (CTX) were assessed at baseline, and 6 and 12 months. Results: Twenty-nine patients entered the study. Degarelix administration was associated with a significant decrease in BMD after 12 months (2.4% reduction from baseline at lumbar spine). Serum CTX and ALP increased significantly (median increase from baseline 99% and 19.3%, respectively). An inverse correlation was observed between ALMI and CTX, but not ALP, at both baseline (Pearson r = -0.62, P < .0001) and month 12 (Pearson r = -0.41, P = .032). Moreover, a significant inverse correlation between changes in ALMI and CTX at 12 months (Pearson r = -0.43, P = .019) and a direct relationship between changes of ALMI and ALP (Pearson r = 0.44, P = .016) during degarelix therapy were observed. Conclusion: Degarelix administration is associated with a significant decrease in BMD and increase in bone turnover markers. ALMI is a promising predictor of bone loss in prostate cancer patients receiving androgen deprivation therapy, and ALMI changes during therapy are associated with bone turnover derangement favoring bone quality alterations. [ABSTRACT FROM AUTHOR]

Background: Phase 2 trial endpoints that can be utilized in high-risk biochemical recurrence (BCR) after prostatectomy as a way of more rapidly identifying treatments for phase 3 trials are urgently needed. The efficacy of abiraterone acetate plus prednisone (AAP) in BCR is unknown. Objective: To compare the rates of complete biochemical responses after testosterone recovery after 8 mo of AAP and degarelix, a gonadotropin-releasing hormone antagonist, alone or in combination. Design, setting, and participants: Patients with BCR (prostate-specific antigen [PSA] ≥1.0 ng/ml, PSA doubling time ≤9 mo, no metastases on standard imaging, and testosterone ≥150 ng/dl) after prostatectomy (with or without prior radiotherapy) were included in this study. Intervention: Patients were randomized to AAP (arm 1), AAP with degarelix (arm 2), or degarelix (arm 3) for 8 mo, and monitored for 18 mo. Outcome measurements and statistical analysis: The primary endpoint was undetectable PSA with testosterone >150 ng/dl at 18 mo. Secondary endpoints were undetectable PSA at 8 mo and time to testosterone recovery. Results and limitations: For the 122 patients enrolled, no difference was found between treatments for the primary endpoint (arm 1: 5.1% [95% confidence interval {CI}: 1–17%], arm 2: 17.1% [95% CI: 7–32%], arm 3: 11.9% [95% CI: 4–26%]; arm 1 vs 2, p = 0.93; arm 2 vs 3, p = 0.36). AAP therapy showed the shortest median time to testosterone recovery (36.0 wk [95% CI: 35.9–36.1]) relative to degarelix (52.9 wk [95% CI: 49.0–56.0], p < 0.001). Rates of undetectable PSA at 8 mo differed between AAP with degarelix and degarelix alone (p = 0.04), but not between AAP alone and degarelix alone (p = 0.12). Limitations of this study include a lack of long-term follow-up. Conclusions: Rates of undetectable PSA levels with testosterone recovery were similar between arms, suggesting that increased androgen suppression with AAP and androgen deprivation therapy (ADT) is unlikely to eradicate recurrent disease compared with ADT alone. Patient summary: We evaluated the use of abiraterone acetate plus prednisone (AAP) and androgen deprivation therapy (ADT), AAP alone, or ADT alone in men with biochemically recurrent, nonmetastatic prostate cancer. While more men who received the combination had an undetectable prostate-specific antigen (PSA) level at 8 mo on treatment, once men came off treatment and testosterone level rose, there was no difference in the rates of undetectable PSA levels. This suggests that the combination is not able to eradicate disease any better than ADT alone.

Relugolix is the first oral gonadotrophin-releasing hormone (GnRH) receptor antagonist. Based on the phase III HERO trial results, relugolix received Food and Drug Administration approval for adult patients with advanced prostate cancer (PCa). We provide an overview of the preclinical and clinical development of relugolix and its role in the current treatment landscape of PCa. Relugolix leads to rapid inhibition of testicular production of testosterone and its rapid recovery upon discontinuation. In the HERO trial, relugolix was associated with a superior cardiovascular safety profile compared to GnRH agonists. These attributes make relugolix a promising therapy for patients with preexisting cardiovascular comorbidities, those pursuing intermittent androgen deprivation therapy, and those who desire rapid testosterone recovery during 'off-treatment' periods. In the HERO trial, very few patients received concomitant enzalutamide (n = 17, 2.7%) or docetaxel (n < 10, 1.3%). Safety of relugolix has not been established in combination with many androgen-receptor-axis targeted therapies (e.g. abiraterone, apalutamide), cabazitaxel, or lutetium Lu 177 vipivotide tetraxetan, which precludes its use in combination with these agents. In addition, being an oral drug, relugolix may also be associated with challenges of affordability, adherence, and compliance in this predominantly elderly population. [ABSTRACT FROM AUTHOR]

Background and Objective: Gonadotropin-releasing hormone (GnRH) antagonists and agonists are cornerstone treatments in prostate cancer. However, evidence regarding the comparative cardiovascular safety of these drugs from clinical trials is inconclusive. The objective of this study was to systematically assess the risk of adverse cardiovascular events of GnRH antagonists compared with GnRH agonists across real-world evidence studies., Methods: We conducted a systematic search of PubMed, Embase, Cochrane Library, Scopus, and Web of Science (2008-2023). We included real-world evidence studies comparing the risk of cardiovascular outcomes of GnRH antagonists with those of GnRH agonists among patients with prostate cancer. We conducted a meta-analysis of effect estimates across studies at a low or moderate risk of bias, assessed via the Risk of Bias in Non-Randomized Studies of Interventions (ROBINS-I) tool, using random-effect models., Key Findings and Limitations: Among ten included studies, four were classified as having a moderate and six as having a serious risk of bias. Across three studies at a moderate risk of bias in the primary analysis, degarelix was associated with an increased risk (pooled relative risk [RR]: 1.31, 95% confidence interval [CI]: 1.14-1.51) of major adverse cardiovascular events (MACEs). An augmented risk was observed in two studies among patients with a history of cardiovascular disease (pooled RR: 1.31, 95% CI: 1.11-1.56) compared with one study among patients without a history of cardiovascular disease (RR: 1.15, 95% CI: 0.83-1.59)., Conclusions and Clinical Implications: Real-world evidence studies indicate that degarelix, compared with GnRH agonists, is associated with a modest increased risk of MACEs, particularly among patients with a history of cardiovascular disease. However, residual confounding due to the treatment of high-risk patients with degarelix may account for these findings. Additional large studies with detailed data on tumor characteristics and cardiovascular risk factors are needed to confirm these findings., Patient Summary: In this systematic evaluation of evidence among patients diagnosed with prostate cancer in routine care, degarelix was associated with higher cardiovascular adverse outcomes than gonadotropin-releasing hormone agonists., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

What steps involved in degarelix (Firmagon®, Ferring Pharmaceuticals) administration and patient care do specialist nurses consider most important to reduce the risk of associated injection site reactions, and are there any variations in administration and materials used to support optimal injection technique? Degarelix is a GnRH antagonist indicated for the first‐line treatment of advanced prostate cancer that effectively suppresses testosterone production in the testes without an initial testosterone surge and possible subsequent disease flare—both typical features associated with GnRH agonists. However, injection site reactions can occur after subcutaneous injection of degarelix, which are unpleasant for patients and may represent a limiting factor for its use by healthcare professionals. The objective of this study was to reach consensus on key steps involved in degarelix administration and patient care to minimise injection site reaction risk. Injection site reactions have been associated with subcutaneous injection of degarelix in several published studies; they are usually transient, mild‐to‐moderate, and occur mainly with the initial dose. Information on prevention is limited, one research group suggesting that the injection method may contribute to injection site reaction risk, and another describing specific injection techniques and strategies developed by Canadian nurses and physicians aiming to prevent degarelix injection site reactions. An online pre‐meeting survey regarding degarelix administration and injection site reactions was conducted to gather insights from 11 international specialist nurses. Survey results supported the development of 25 best practice consensus statements for the in‐person Delphi meeting (Warsaw, Poland), attended by 15 international specialist nurses. Statements focused on degarelix reconstitution, administration and patient care. Participants voted anonymously and collated responses were discussed after each voting round to understand if consensus could be achieved. If no consensus was reached after the first voting round, up to two more voting rounds were considered. Consensus was defined as "agreement" or "disagreement" by ≥75% of nurses, with ≤15% having the opposite opinion. In the pre‐meeting survey, nurses reported that they observed injection site reactions in up to a third of treated patients after degarelix injection, and all agreed that the administration technique was, to some degree, related to the development of injection site reactions; a variety of materials were being used as guidance. In the Delphi study, consensus was reached on 5 of 9 statements related to reconstitution steps and 14 of 16 statements related to administration steps and patient care, all of which were considered to be important in the prevention of injection site reactions. This study confirmed country‐specific variations in the degarelix administration technique and highlighted pivotal steps that may potentially contribute to injection site reactions. Importantly, all nurses agreed that technique optimisation holds the potential to reduce the occurrence of such reactions ("yes," 45%; "possibly," 55%; "no," 0%). The findings should be considered along with other available materials and guidance to help reduce the risk of injection site reactions in patients with advanced prostate cancer treated with degarelix. [ABSTRACT FROM AUTHOR]

ObjectiveTo explore the cost-effectiveness of degarelix acetate for injection (degarelix) compared to leuprorelin in prostate cancer (Pca) castration treatment from Chinese healthcare system perspective.MethodsA Markov model, adapted from the one established in Finland was conducted for the cost-effectiveness analysis of degarelix and leuprorelin for Pca treatment. The main data were derived from global phase III clinical trials of degarelix (CS21), published study and expert surveys. Outcomes, utility and costs of prostate cancer patients were calculated on a 30-year time horizon. The CS21 study based population of intention-to-treat (ITT) population and three scenarios were modeled. Taking three times of the Gross domestic product (GDP) per capita (242,928 yuan, 2021) as the acceptable threshold for cost-effectiveness. One-way and probabilistic sensitivity analyses were performed on key parameters, including transition probabilities, costs, utility, and discount rate to test the robustness of the model.ResultsBase case analysis for ITT population revealed that total costs of degarelix and leuprorelin were 566,226 yuan and 489,693 yuan, while the total quality-adjusted life years (QALYs) were 5.19 and 4.51 during the 30-year time horizon, resulting an incremental cost effectiveness ratio (ICER) of 112,674 yuan/QALY which was 1.39 times the GDP per capita, lower than willingness-to-pay level of three times the GDP per capita. The results for scenario analyses revealed that compared to leuprorelin, degarelix for Pca treatment in China was cost-effective. One-way sensitivity analysis showed that the model was most sensitive to price of 80 mg degarelix, utility of 1st-line therapy, hazard ratio of PSA recurrence, price of 3.75 mg leuprorelin, response rate of docetaxel per cycle, and discount rate of cost. In probabilistic sensitivity analysis, compared to leuprorelin, the probability of degarelix to be cost-effective was 53 and 81% for willingness-to-pay threshold of one and three times the GDP per capita.ConclusionCompared to leuprorelin, degarelix for prostate cancer treatment is cost-effective. Moreover, scenario, one-way, and probabilistic sensitivity analyses revealed that the model was robust.

Yi-Fu Liu, Sheng-Qiang Fu, Yu-Chang Yan, Bin-Bin Gong, Wen-Jie Xie, Xiao-Rong Yang, Ting Sun, Ming Ma Department of Urology, The First Affiliated Hospital of Nanchang University, Nanchang, 330000, Jiangxi Province, People’s Republic of ChinaCorrespondence: Ming MaDepartment of Urology, The First Affiliated Hospital of Nanchang University, Nanchang, 330000, Jiangxi Province, People’s Republic of ChinaEmail mm15070835359@163.comAbstract: Gonadotropin-releasing hormone (GnRH) receptor agonists are still the most commonly used androgen deprivation treatment (ADT) drugs for prostate cancer in clinical practice. Currently, the GnRH receptor antagonists used for endocrine therapy for prostate cancer primarily include degarelix and relugolix (TAK-385). The former is administered by subcutaneous injection, while the latter is an oral drug. Compared to GnRH agonists, GnRH antagonists reduce serum testosterone levels more rapidly without an initial testosterone surge or subsequent microsurges. This review focuses on the mechanism of action of GnRH antagonists and agonists, the developmental history of GnRH antagonists, and emerging data from clinical studies of the two antagonists used as endocrine therapy for prostate cancer.Keywords: gonadotropin-releasing hormone, prostate cancer, degarelix, relugolix

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. [ABSTRACT FROM AUTHOR]

Copyright of Der Urologe A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Der Urologe A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: To establish non-inferiority of gonadotropin-releasing hormone degarelix compared with goserelin in suppressing and maintaining castrate testosterone levels from Day 28 to Day 364 in Chinese patients with prostate cancer. Methods: This is an open-label, multi-centre study in which men aged ≥18 years were randomised in a 1:1 ratio to once-a-month subcutaneous injection of either degarelix (240/80 mg) or goserelin (3.6 mg) for 12 months. The primary endpoint was difference in 1-year cumulative probability of suppressing testosterone to ≤0.5 ng/mL. Non-inferiority was to be established if the lower 95% confidence interval (CI) limit for difference in cumulative probability between the treatment arms was greater than −10%. Secondary endpoints included cumulative probability of prostate-specific-antigen-progression-free-survival (PSA-PFS). Safety was also assessed. Results: Baseline demographics and disease characteristics were similar between degarelix (n=142) and goserelin (n=141) treatment arms. The difference in cumulative probability of maintaining castrate levels from Day 28–364 was 3.6% (95% CI:−1.5%, 8.7%), demonstrating non-inferiority of degarelix. The cumulative probability of PSA-PFS at Day 364 was higher for degarelix (82.3%, 95% CI: 74.7%, 87.7%) versus goserelin (71.7%, 95% CI: 63.2%, 78.5%, p=0.038). Adverse events (AEs) were similar between treatment arms, except for more injection site reactions with degarelix versus goserelin. Four (2.8%) and nine (6.4%) patients discontinued due to AEs in degarelix and goserelin groups, respectively. Conclusion: Degarelix was non-inferior to goserelin in achieving and maintaining testosterone suppression at castrate levels during 1-year treatment. PSA-PFS was significantly higher with degarelix, suggesting improved disease control. Both treatments were well tolerated.

Functioning pituitary gonadotropinomas are rarely described and comprise only a small portion of pituitary adenomas. Most of them are macroadenomas and cause endocrine dysfunctions usually presenting as either ovarian hyperstimulation, testicular enlargement or precocious puberty. Transsphenoidal resection is currently regarded as the treatment of choice, while other treatment options are considered ineffective and are rarely used.

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.

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. [ABSTRACT FROM AUTHOR]

GnRH antagonist and GnRH agonist are widely used as androgen deprivation therapy for metastatic prostate cancer. A previous report demonstrated that patients with PSA levels of >20 ng/mL using GnRH antagonists showed favorable outcomes in comparison to those using GnRH agonists. An 82-year old male patient with edema, a stony hard nodule on his prostate, and an initial PSA level of 6,717 ng/mL was referred to our hospital due to suspected prostate cancer. He received prostate needle biopsy and was diagnosed with prostate cancer with bone metastasis, with a Gleason Score of 4 + 4 = 8. He was then treated with a GnRH agonist (leuprorelin acetate) and bicalutamide from July 2015. Although his PSA level decreased to 582.0 ng/mL in December 2015, his PSA level gradually increased and CRPC developed. He indicated that he did not wish to take 2nd generation anti-androgen drugs or receive systemic chemotherapy. We introduced a GnRH antagonist (degarelix) in February 2015; his PSA level did not change and his CRPC was controlled. We herein report a case in which changing a GnRH agonist to a GnRH antagonist contributed to CRPC control.

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. 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. 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. 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. 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. The behavioral side effects associated with the use of degarelix may be restricted to sexual behaviors. Strengths include the objective measurement of sexual behaviors. The study is limited in that only one ADT was examined. 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. [ABSTRACT FROM AUTHOR]

Purpose: Androgen deprivation therapy (ADT) is the mainstay for the management of metastatic prostate cancer. Available pharmaceutical ADTs include gonadotropin-releasing hormone (GnRH) agonists and antagonists. Here, real-world data are presented from the UK general practitioner Optimum Patient Care Research Database. The study investigated the hypothesis that GnRH antagonists have lower cardiac event rates than GnRH agonists. Methods: The incidence of cardiac events following initiation of GnRH antagonist or agonist therapy was investigated in a population-based cohort study conducted in UK primary care between 2010 and 2017. Results: Analysis of real-world data from the UK primary care setting showed that relative risk of experiencing cardiac events was significantly lower with degarelix, a GnRH antagonist, compared with GnRH agonists (risk ratio: 0.39 [95% confidence interval 0.191, 0.799]; p = 0.01). Patients that received degarelix as first-line treatment switched treatment more frequently (33.7%), often to a GnRH agonist, than those who initiated treatment with a GnRH agonist (6.7–18.6%). Conclusion: Screening for known or underlying vascular disease and identifying those at high risk of a cardiac event is important for risk mitigation in patients with prostate cancer receiving hormone therapy. The GnRH antagonist degarelix conferred a significantly lower risk of cardiac events than GnRH agonists. Prior to treatment, patients should be stratified based on level of cardiovascular (CV) risk, and appropriate lifestyle, and pharmacological interventions to mitigate CV risk should be recommended. CV risk factors and patient response to the intervention should be monitored at regular intervals. [ABSTRACT FROM AUTHOR]

Résumé Contexte L’objectif de notre étude rétrospective était d’évaluer la survie à 5 ans et le délai de transition du cancer de la prostate hormono-sensible au cancer de la prostate résistant à la castration chez des patients porteurs d’un cancer de la prostate hormono-sensible qui étaient traités par un antagoniste de la gonadolibérine, le dégarélix. Un autre objectif était d’évaluer les effets sur les résultats cliniques et oncologiques du remplacement du dégarélix par un agoniste de la gonadolibérine après obtention d’un état stable et contrôlé. Résultats Notre analyse repose sur les données de 108 patients atteints d’un cancer de la prostate traités par dégarélix. Parmi ceux-ci, le traitement par dégarélix a été remplacé par un agoniste de la gonadolibérine chez 57 (groupe modifié), et le traitement par dégarélix a été poursuivi chez les autres patients (groupe inchangé). La survie globale à 5 ans était statistiquement plus élevée pour le groupe modifié (96.6%) que pour le groupe inchangé (74,1%; p = 0.006). Les chances de survie cancer-spécifiques à 5 ans était également plus élevées pour le groupe modifié (100%) que pour le groupe inchangé (84,6%; p = 0.027). Le délai moyen de transition du cancer de la prostate hormono-sensible au cancer de la prostate résistant à la castration était comparable dans le groupe modifié (43,3 mois) et dans le groupe inchangé (35,2 mois). Des taux sériques plus bas d’antigène spécifique de la prostate et de phosphatase alcaline ont été maintenus après le remplacement du dégarélix par un agoniste de la gonadolibérine. Conclusions Le dégarélix est. efficace dans le traitement du cancer de la prostate. Le traitement par dégarélix peut aussi être remplacé en toute sécurité par un agoniste de la gonadolibérine sans aucun effet clinique ou oncologique indésirable. Mots-clés Antagonistes et inhibiteurs de la gonadolibérine, Agoniste de la gonadolibérine, Cancer de la prostate, Dégarélix, Résistant à la castration

External beam radiotherapy (EBRT) with neoadjuvant/adjuvant androgen deprivation therapy (ADT) is an established treatment option to prolong survival for patients with intermediate- and high-risk prostate cancer (PCa). Relugolix, an oral gonadotropin-releasing hormone (GnRH) receptor antagonist, was evaluated in this clinical setting in comparison with degarelix, an injectable GnRH antagonist. To evaluate the safety and efficacy of relugolix to achieve and maintain castration. A phase 2 open-label study was conducted in 103 intermediate-risk PCa patients undergoing primary EBRT and neoadjuvant/adjuvant ADT between June 2014 and December 2015. Patients randomly assigned (3:2) to 24-wk treatment with either daily oral relugolix or 4-wk subcutaneous depot degarelix (reference control). The primary endpoint was the rate of effective castration (testosterone <1.73 nmol/l) in relugolix patients between 4 and 24 wk of treatment. Secondary endpoints included rate of profound castration (testosterone <0.7 nmol/l), prostate-specific antigen (PSA) levels, prostate volume, quality of life (QoL) assessed using the Aging Males' Symptoms scale, and the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life (30-item EORTC core questionnaire [EORTC QLQ-C30] and 25-item EORTC prostate cancer module [EORTC QLQ-PR25]) questionnaires, and safety. No formal statistical comparisons with degarelix were planned. Castration rates during treatment were 95% and 82% with relugolix and 89% and 68% with degarelix for 1.73 and 0.7 nmol/l thresholds, respectively. Median time to castration in the relugolix arm was 4 d. During treatment, PSA levels and prostate volumes were reduced in both groups. Three months after discontinuing treatment, 52% of men on relugolix and 16% on degarelix experienced testosterone recovery (statistical significance of differences not tested). Mean and median QoL scores improved following treatment discontinuation. The most common adverse event was hot flush (relugolix 57%; degarelix 61%). Lack of blinding was a potential limitation. Relugolix achieved testosterone suppression to castrate levels within days and maintained it over 24 wk with a safety profile consistent with its mechanism of action. Oral once-daily relugolix may be a novel oral alternative to injectable androgen deprivation therapies. The phase 2 study C27003 demonstrated relugolix, an oral gonadotropin-releasing hormone antagonist, achieves and maintains testosterone castration for 24 wk in >90% of men with localised intermediate- and high-risk prostate cancer requiring neoadjuvant and/or adjuvant androgen deprivation therapy to external beam radiation therapy. [ABSTRACT FROM AUTHOR]

We assessed the effects of antiandrogen therapy on ECG parameters of ventricular repolarization related to arrhythmic risk in 35 patients aged 70.3 ± 7 years with advanced prostate cancer treated with degarelix associated with enzalutamide (group A, 26 patients) or degarelix monotherapy (group B, 9 patients). We analyzed Fridericia corrected Q-T interval (QTc), Q-T dispersion (QTd), J-Tpeak interval (JTp), mean and maximum Tpeak-Tend interval (Tpe) and Tpe/QT ratio, Tpeak-Tend dispersion (Tped), index of cardio-electrophysiological balance (iCEB) from ECG tracings, and occurrence of ventricular premature beats (VPB) recorded by Holter ECG, before initiation of medication (M0) and after 6 months of treatment (M1). The groups had similar demographics except for a higher prevalence of prior myocardial infarction in group B (p = 0.01). All patients had low serum testosterone at M1. Baseline QTc, QTd, maxTpe/QT, meanTpe, maxTpe, Tped values were higher in B compared to A. They had a significant prolongation at M1 only in A. 20 patients in A and 6 in B had a 10% prolongation or decrease of iCEB (p = 0.66). In 5 patients, VPB severity increased from non-complex to complex: 3 in A and 2 in B (p = 0.31), but no sustained ventricular arrhythmia was registered. In conclusion, after 6 months of treatment, patients with hypogonadism on degarelix associated with enzalutamide had significant prolongation of QTc, QTd, maxTpe, meanTpe/QT, maxTpe/QT, Tped compared to patients on degarelix alone. The proportion of patients with 10% iCEB variation was similar between groups. There was no record of severe arrhythmias during the first 6 months of treatment. [ABSTRACT FROM AUTHOR]

Purpose: In a mouse model, degarelix generated the least metabolic consequences via low follicle-stimulating hormone (FSH) levels compared with orchiectomy and leuprolide after 4 months of androgen deprivation therapy (ADT). Here, we comparatively investigated the influence of ADT with degarelix or leuprolide on the development of metabolic syndrome in patients with prostate cancer (PCa). Methods: Patients with hormone-naive PCa were recruited. Eligible patients were randomized (1:1) to monthly degarelix or monthly leuprolide for 6 months. Key trial variables were monitored monthly. The primary endpoint was changes in fasting blood sugar (FBS). Secondary endpoints were changes in body weight, abdominal circumference, lipid profiles, and hemoglobin A1c (HbA1c) and FSH levels. Computed tomography was performed to measure subcutaneous and visceral fat areas before and after 6 months of ADT. Data were analyzed using the χ2 test, Student's t test, and analysis of variance. Results: From the 100 patients registered, 85 completed the trial (degarelix: 40 patients; leuprolide: 45 patients). Mean increases in FBS did not differ between the two arms. Similarly, there were no differences between the arms in mean increases in body weight, abdominal circumference, lipid profiles, HbA1c, or subcutaneous and visceral fat areas. Follicle-stimulating hormone levels were significantly lower in the degarelix arm than in the leuprolide arm (p < 0.05). Conclusions: Lipid and glucose metabolism did not differ significantly between the arms, while FSH levels were significantly lower in the degarelix arm. [ABSTRACT FROM AUTHOR]

Suguru Tokiwa,1 Hiroaki Shimmura,1 Shuhei Nomura,2–4 Ryota Watanabe,1 Minoru Kurita,1 Naoto Yoshida,1 Kaori Yamashita,1 Yoshitaka Nishikawa,5 Alexander Kouzmenko,6 Shigeaki Kato4 1Department of Urology, Jyoban Hospital, Tokiwa Foundation, Iwaki, Fukushima, Japan; 2Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; 3Department of Global Health Policy, Graduate School of Medicine, The University of Tokyo, Tokyo, 4Research Institute of Innovative Medicine, Tokiwa Foundation, Iwaki, 5Department of Health Informatics, School of Public Health, Kyoto University, Kyoto, Japan; 6Department of Life Sciences, Alfaisal University, Riyadh, Kingdom of Saudi Arabia 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. Keywords: GnRH antagonists, prostate cancer, degarelix, discontinuation, diabetes, antithrombotic treatment

GnRH antagonist and GnRH agonist are widely used as androgen deprivation therapy for metastatic prostate cancer. A previous report demonstrated that patients with PSA levels of >20 ng/mL using GnRH antagonists showed favorable outcomes in comparison to those using GnRH agonists. An 82-year old male patient with edema, a stony hard nodule on his prostate, and an initial PSA level of 6,717 ng/mL was referred to our hospital due to suspected prostate cancer. He received prostate needle biopsy and was diagnosed with prostate cancer with bone metastasis, with a Gleason Score of 4 + 4 = 8. He was then treated with a GnRH agonist (leuprorelin acetate) and bicalutamide from July 2015. Although his PSA level decreased to 582.0 ng/mL in December 2015, his PSA level gradually increased and CRPC developed. He indicated that he did not wish to take 2nd generation anti-androgen drugs or receive systemic chemotherapy. We introduced a GnRH antagonist (degarelix) in February 2015; his PSA level did not change and his CRPC was controlled. We herein report a case in which changing a GnRH agonist to a GnRH antagonist contributed to CRPC control. [ABSTRACT FROM AUTHOR]

Androgen deprivation therapy (ADT) is currently the mainstay of treatment for advanced prostate cancer. The peptide formulations of gonadotropin-releasing hormone (GnRH) antagonists need to be given subcutaneously every month. This led to the development of an oral, nonpeptide GnRH antagonist formulation relugolix which promptly lowers the levels of testosterone, luteinizing hormone, and follicular-stimulating hormone. On December 18, 2020, the US Food and Drug Administration approved relugolix for the treatment of adult advanced prostate cancer. The recommended loading dose of 360 mg on the 1st day of treatment, followed by 120 mg once daily orally, approximately the same time each day. The maximum plasma concentration (Tmax) is obtained within 2.25 h and is metabolized to a major extent by CYP3A mediated mechanism. Hot flushes, musculoskeletal pain, and fatigue are some of its common adverse effects. High rates of testosterone suppression with a limited adverse event profile make it an ideal therapy for the treatment of advanced prostate cancer. [ABSTRACT FROM AUTHOR]

IntroductionA drawback of gonadotropin-releasing hormone (GnRH) antagonist protocols in in vitro fertilization (IVF) is that they have limited flexibility in cycle programming. This proof of concept study explored the efficacy of a single-dose, long-acting GnRH antagonist IVF protocol. Trial registration number is NCT03240159, retrospectively registered on March 08, 2017.Materials and methodsThe efficacy of a single-dose long-acting antagonist, degarelix, was explored initially in healthy donors and subsequently in infertile patients. In the first part, five healthy oocyte donors underwent ovarian stimulation with this new protocol: in the late luteal phase, at day 24, a bolus injection of degarelix was administered subcutaneously to control the LH surge in the follicular phase. Ovarian stimulation with gonadotropins was initiated subsequently from day 7 to day 10. End points were first to inhibit the LH surge later in the follicular phase and, second, to retrieve mature oocytes for IVF. In the second part, five infertile women received the same bolus injection of degarelix administered during the luteal phase at day 24. Different gonadotropin starting days (day 2 through day 8) were tested in order to observe possible differences in ovarian stimulation. In these infertile patients, fresh embryo transfers were performed to assess the pregnancy efficacy of this protocol on pregnancy outcomes and to address any possible negative effects on endometrium receptivity.ResultsIn the first part of the study, all donors were effectively downregulated with a single luteal dose of 0.5 ml of degarelix for up to 22 days until the final oocyte maturation triggering day. Mature oocytes were retrieved after 36 h from all patients and all produced 2–7 blastocysts. In the second part, all five infertile patients achieved sufficient LH downregulation and completed ovarian stimulation without any LH surge. All patients (except one with freeze all strategy) had blastocysts transferred and pregnancy occurred in three out of five women.ConclusionA single dose of the long-acting antagonist degarelix during the luteal phase appears to be effective in downregulating hypophysis during ovarian stimulation. This represents a possible new protocol for IVF, which should be further elucidated in RCTs.

Purpose: To assess the noninferiority, efficacy, and safety of degarelix in achieving and maintaining testosterone at castrate levels (≤0.5 ng/mL) in Korean patients (CS42) versus non-Asian patients with prostate cancer (PCa). Methods: A Phase III, open-label, multicenter, single-arm trial was conducted in Korean patients with PCa. Degarelix was administered at a starting dose of 240 mg followed by monthly (28-day intervals) maintenance doses of 80 mg (240/80 mg dose regimen) for 7 months. The results were compared with non-Asian patients receiving degarelix 240/80 mg in the CS21 study. Results: The estimated difference in the cumulative probabilities of testosterone ≤0.5 ng/mL from Day 28 to Day 196 between the trials was −2.3% (96.7% in CS42 vs. 99.0% in CS21). The lower limit of the 95% confidence interval was −5.5%, i.e., above the predefined noninferiority limit of −10% and thus noninferiority was established. Decreases in serum testosterone, prostate-specific antigen, and luteinizing hormone over time were similar in CS42 and CS21. There were no clinically significant differences in incidence of treatment-emergent adverse events (72% in CS42 vs. 70% in CS21) and changes in clinical chemistry and hematology parameters between the two trials. The most common adverse event was injection-site reaction. Conclusions: Overall, degarelix was effective and well tolerated in Korean patients. Testosterone suppression was noninferior to that in non-Asian patients and safety findings were as would be expected for elderly men with PCa undergoing androgen deprivation therapy.

Objective: This multicenter, retrospective, observational study investigated baseline characteristics and clinical outcomes in patients with hormone-sensitive prostate cancer who received primary androgen deprivation therapy, using Japan Study Group of Prostate Cancer registry data., Methods: Among patients in the Japan Study Group of Prostate Cancer registry, those who initiated primary androgen deprivation therapy and were aged 20 years or older were enrolled in this study. The primary endpoint was time to disease progression, defined as time from primary androgen deprivation therapy initiation to either prostate-specific antigen or clinical progression. Secondary endpoints included prostate-specific antigen progression-free survival, prostate-specific antigen response (90% or greater reduction from baseline) and distribution of second-line treatment., Results: Of the 2494 patients (goserelin, n = 564; leuprorelin, n = 1148; surgical castration, n = 161; degarelix, n = 621), those who received degarelix had higher prostate-specific antigen levels and Gleason scores and were at a more advanced clinical stage than those receiving goserelin or leuprorelin. The median time to disease progression (identical to the prostate-specific antigen progression-free survival result) was not reached for goserelin and leuprorelin, 52.7 months for surgical castration and 54.0 months for degarelix. Although baseline prostate-specific antigen values in the degarelix cohort were higher than those of the leuprorelin or goserelin cohorts, prostate-specific antigen responses were not different among the three cohorts. Regarding second-line treatment, the largest patient group received degarelix followed by leuprorelin (n = 195)., Conclusions: This study clarified patient characteristics and long-term effectiveness of primary androgen deprivation therapy in real-world clinical practice. Japanese urologists appear to select appropriate primary androgen deprivation therapy based on patient background and tumour characteristics, with degarelix largely reserved for higher risk patients., (© The Author(s) 2023. Published by Oxford University Press.)

Background: Gonadotropin releasing hormone (GnRH) antagonists suppress follicle-stimulating hormone (FSH) to lower levels than GnRH agonists. This may partially explain the differences between these agents on prostate cancer outcomes. In this post-hoc analysis, FSH and prostate specific antigen (PSA) responses and the impact of cross-over from leuprolide to degarelix were evaluated from a 1-year comparative study (CS21) and its extension study (CS21A). Materials and methods: Overall, 610 patients were enrolled in CS21, wherein PSA and FSH levels were evaluated monthly. CS21A evaluated 386 patients, including those previously treated with degarelix (n = 251) who continued to receive degarelix, and those previously treated with leuprolide (n = 135) who crossed-over to receive degarelix. PSA and FSH levels were evaluated in CS21A for 3 months after cross-over. The associations between measurements were assessed using Spearman's correlation coefficient. The impact of class variables on FSH suppression were evaluated using Analysis of Variance. Results: Rapid PSA and FSH suppression was observed and maintained in the degarelix arm (CS21 and CS21A), while patients on leuprolide experienced rising PSA during CS21. Patients crossed-over from leuprolide to degarelix achieved a suppression of FSH and a significant PSA decrease. PSA and FSH levels were significantly (p < .05) correlated at months 1, 3, 6, 12 and 13 in the degarelix arm. Conclusions: Significant FSH suppression with GnRH antagonists may explain its advantage over GnRH agonists in terms of better prostate cancer control. The effect of profound FSH suppression is analogous to the need for profound testosterone suppression for tumor control. [ABSTRACT FROM AUTHOR]

Two male Asian elephants (bulls 1 and 2) in musth were subcutaneously injected with a long-acting gonadotropin-releasing hormone (GnRH) antagonist, degarelix acetate (240 μg/kg; total dose of 960 mg). Musth behavior (MB) and temporal gland secretions (TGS) were monitored and serum testosterone concentrations were determined. In bull 1, MB and TGS ceased on day 1 and reappeared 5.5 mo after the treatment (day 0). During the subsequent musth cycle, MB and TGS ceased on day 1 and did not appear for 4 mo. In bull 2, MB and TGS ceased at day 7 after the treatment. Musth behavior and TGS recurred on Day 11 and continued for 1 wk, then disappeared for 8 mo. Serum testosterone concentrations decreased (P < 0.05) in all occasions from day 0 (29.8 ± 15.8 ng/ml; mean ± SEM) to day 1 (2.2 ± 1.1 ng/ml), suggesting a sudden drop in circulating testosterone in musth elephants after the GnRH-antagonist treatment. [ABSTRACT FROM AUTHOR]