LHRH analogues as anticancer agents: pituitary and extrapituitary sites of action

Inhibitors of the transactivation domain of androgen receptor as a therapy for prostate cancer

The androgen receptor (AR) is a modular transcription factor which functions as a master regulator of gene expression. AR protein is composed of three functional domains; the ligand-binding domain (LBD); DNA-binding domain (DBD); and the intrinsically disordered N-terminal transactivation domain (TAD). AR is transactivated upon binding to the male sex hormone testosterone and other androgens. While the AR may tolerate loss of its LBD, the TAD contains activation function-1 (AF-1) that is essential for all AR transcriptional activity. AR is frequently over-expressed in most prostate cancer. Currently, androgen deprivation therapy (ADT) in the form of surgical or chemical castration remains the standard of care for patients with high risk localized disease, advanced and metastatic disease, and those patients that experience biochemical relapse following definitive primary treatment. Patients with recurrent disease that receive ADT will ultimately progress to lethal metastatic castration-resistant prostate cancer. In addition to ADT not providing a cure, it is associated with numerous adverse effects including cardiovascular disease, osteoporosis and sexual dysfunction. Recently there has been a renewed interest in investigating the possibility of using antiandrogens which competitively bind the AR-LBD without ADT for patients with hormone sensitive, non-metastatic prostate cancer. Here we describe a class of compounds termed AR transactivation domain inhibitors (ARTADI) and their mechanism of action. These compounds bind to the AR-TAD to inhibit AR transcriptional activity in the absence and presence of androgens. Thus these inhibitors may have utility in preventing prostate cancer growth in the non-castrate setting.

Cost-Effectiveness Analysis of Triptorelin, Goserelin, and Leuprolide in the Treatment of Patients With Metastatic Prostate Cancer: A Societal Perspective

OBJECTIVES

Metastatic prostate cancer is the most common malignant cancer and the second leading cause of death due to various types of cancer among men after lung cancer. This study aimed to analyze the cost-effectiveness of triptorelin, goserelin, and leuprolide in the treatment of the patients with metastatic prostate cancer from the societal perspective in Iran in 2020.

METHODS

This is a cost-effectiveness study in which a 20-year Markov transition modeling was applied. In this study, local cost and quality-of-life data of each health state were gathered from cohort of patients. The TreeAge pro 2020 and Microsoft Excel 2016 software were used to simulate cost-effectiveness of each treatment in the long term. The one-way and probabilistic sensitivity analyses were also performed to measure robustness of the model outputs.

RESULTS

The findings indicated that the mean costs and utility gained over a 20-year horizon for goserelin, triptorelin, and leuprolide treatments were $ 13 539.13 and 6.365 quality-adjusted life-years (QALY), $ 18 124.75 and 6.658 QALY, and $ 26 006.92 and 6.856 QALY, respectively. Goserelin was considered as a superior treatment option, given the estimated incremental cost-effectiveness ratio. The one-way and probabilistic sensitivity analyses confirmed the robustness of the study outcomes.

CONCLUSIONS

According to the results of the present study, goserelin was the most effective and cost-effective strategy versus 2 other options. It could be recommended to policy makers of the Iran healthcare system to prioritize it in clinical guidelines and reimbursement policies.

Use of new and emerging cancer drugs: what the cardiologist needs to know

The last decade has witnessed a paradigm shift in cancer therapy, from non-specific cytotoxic chemotherapies to agents targeting specific molecular mechanisms. Nonetheless, cardiovascular toxicity of cancer therapies remains an important concern. This is particularly relevant given the significant improvement in survival of solid and haematological cancers achieved in the last decades. Cardio-oncology is a subspecialty of medicine focusing on the identification and prevention of cancer therapy-related cardiovascular toxicity (CTR-CVT). This review will examine the new definition of CTR-CVT and guiding principles for baseline cardiovascular assessment and risk stratification before cancer therapy, providing take-home messages for non-specialized cardiologists.

AR and PI3K/AKT in Prostate Cancer: A Tale of Two Interconnected Pathways

Prostate cancer (PCa) is the most common cancer in men. The androgen receptor (AR) has a pivotal role in the pathogenesis and progression of PCa. Many therapies targeting AR signaling have been developed over the years. AR signaling inhibitors (ARSIs), including androgen synthesis inhibitors and AR antagonists, have proven to be effective in castration-sensitive PCa (CSPC) and improve survival, but men with castration-resistant PCa (CRPC) continue to have a poor prognosis. Despite a good initial response, drug resistance develops in almost all patients with metastatic CRPC, and ARSIs are no longer effective. Several mechanisms confer resistance to ARSI and include AR mutations but also hyperactivation of other pathways, such as PI3K/AKT/mTOR. This pathway controls key cellular processes, including proliferation and tumor progression, and it is the most frequently deregulated pathway in human cancers. A significant interaction between AR and the PI3K/AKT/mTOR signaling pathway has been shown in PCa. This review centers on the current scene of different AR and PI3K signaling pathway inhibitors, either as monotherapy or in combination treatments in PCa, and the treatment outcomes involved in both preclinical and clinical trials. A PubMed-based literature search was conducted up to November 2022. The most relevant and recent articles were selected to provide essential information and current evidence on the crosstalk between AR and the PI3K signaling pathways. The ClinicalTrials.gov registry was used to report information about clinical studies and their results using the Advanced research tool, filtering for disease and target.

A radiologist’s guide to novel anticancer therapies in the era of precision medicine

Novel anticancer agents have replaced conventional chemotherapy as first line agents for many cancers, with continued new and expanding indications. Small molecule inhibitors act on cell surface or intracellular targets and prevent the downstream signaling that would otherwise permit tumor growth and spread. Anticancer antibodies can be directed against growth factors or may be immunotherapeutic agents. The latter act by inhibiting mechanisms that cancer cells use to evade the immune system. Hormonal agents act by decreasing levels of hormones that are necessary for the growth of certain cancer cells. Cancer therapy protocols often include novel anticancer agents and conventional chemotherapy used successively or in combination, in order to maximize survival and minimize morbidity. A working knowledge of anti-cancer drug classification will aid the radiologist in assessing response on imaging.

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Novel anticancer agents include small molecule inhibitors, antibodies and hormones.

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These agents are predominantly cytostatic and inhibit factors that provide a survival advantage to tumor cells.

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Modern cancer therapy employs a combination of novel anticancer agents and conventional chemotherapy.

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It is essential for radiologists to have a broad understanding of these agents and their mechanisms of action.

Pharmacokinetic and pharmacodynamic evaluation of the new prolonged-release leuprorelin acetate microspheres for injection compared with Enantone® in healthy Chinese male volunteers

PURPOSE

To compare the pharmacokinetics, pharmacodynamics and safety of the new prolonged-release leuprorelin acetate microspheres for injection (3.75 mg) with the reference product Enantone® (3.75 mg).

METHOD

48 healthy male volunteers were enrolled and randomly received a single 3.75 mg dose of the test drug or Enantone®.

RESULTS

There were no significant differences in C_max, AUC_0-t and AUC_0-48 between the test group and reference group (P > 0.05). The 90% confidence intervals of the two groups were 87.49%~112.74%, 97.15%~154.25%, and 80.85%~109.01%, respectively. Twenty-eight days after administration, both groups reached 100.0% castration level; there was no difference in the time from administration to reaching castration level between the two groups (P > 0.05); However, the difference between the two groups in the duration of castration level was statistically significant (P < 0.05). There were no major or serious adverse events, and the severity was mild to moderate.

CONCLUSION

The pharmacokinetic characteristics of leuprorelin in two groups were consistent. The two groups exhibited similar inhibitory effects on testosterone and more subjects in the test group maintained a longer castration time than those in the reference group.

Hormonal Therapy for Prostate Cancer

Huggins and Hodges demonstrated the therapeutic effect of gonadal testosterone deprivation in the 1940s and therefore firmly established the concept that prostate cancer is a highly androgen-dependent disease. Since that time, hormonal therapy has undergone iterative advancement, from the types of gonadal testosterone deprivation to modalities that block the generation of adrenal and other extragonadal androgens, to those that directly bind and inhibit the androgen receptor (AR). The clinical states of prostate cancer are the product of a superimposition of these therapies with nonmetastatic advanced prostate cancer, as well as frankly metastatic disease. Today's standard of care for advanced prostate cancer includes gonadotropin-releasing hormone agonists (e.g., leuprolide), second-generation nonsteroidal AR antagonists (enzalutamide, apalutamide, and darolutamide) and the androgen biosynthesis inhibitor abiraterone. The purpose of this review is to provide an assessment of hormonal therapies for the various clinical states of prostate cancer. The advancement of today's standard of care will require an accounting of an individual's androgen physiology that also has recently recognized germline determinants of peripheral androgen metabolism, which include HSD3B1 inheritance.

Dissecting the Hormonal Signaling Landscape in Castration-Resistant Prostate Cancer

Understanding the molecular mechanisms underlying prostate cancer (PCa) progression towards its most aggressive, castration-resistant (CRPC) stage is urgently needed to improve the therapeutic options for this almost incurable pathology. Interestingly, CRPC is known to be characterized by a peculiar hormonal landscape. It is now well established that the androgen/androgen receptor (AR) axis is still active in CRPC cells. The persistent activity of this axis in PCa progression has been shown to be related to different mechanisms, such as intratumoral androgen synthesis, AR amplification and mutations, AR mRNA alternative splicing, increased expression/activity of AR-related transcription factors and coregulators. The hypothalamic gonadotropin-releasing hormone (GnRH), by binding to its specific receptors (GnRH-Rs) at the pituitary level, plays a pivotal role in the regulation of the reproductive functions. GnRH and GnRH-R are also expressed in different types of tumors, including PCa. Specifically, it has been demonstrated that, in CRPC cells, the activation of GnRH-Rs is associated with a significant antiproliferative/proapoptotic, antimetastatic and antiangiogenic activity. This antitumor activity is mainly mediated by the GnRH-R-associated Gαi/cAMP signaling pathway. In this review, we dissect the molecular mechanisms underlying the role of the androgen/AR and GnRH/GnRH-R axes in CRPC progression and the possible therapeutic implications.

Immunotherapy and Immunotherapy Combinations in Metastatic Castration-Resistant Prostate Cancer

Although most prostate cancers are localized, and the majority are curable, recurrences occur in approximately 35% of men. Among patients with prostate-specific antigen (PSA) recurrence and PSA doubling time (PSADT) less than 15 months after radical prostatectomy, prostate cancer accounted for approximately 90% of the deaths by 15 years after recurrence. An immunosuppressive tumor microenvironment (TME) and impaired cellular immunity are likely largely responsible for the limited utility of checkpoint inhibitors (CPIs) in advanced prostate cancer compared with other tumor types. Thus, for immunologically "cold" malignancies such as prostate cancer, clinical trial development has pivoted towards novel approaches to enhance immune responses. Numerous clinical trials are currently evaluating combination immunomodulatory strategies incorporating vaccine-based therapies, checkpoint inhibitors, and chimeric antigen receptor (CAR) T cells. Other trials evaluate the efficacy and safety of these immunomodulatory agents' combinations with standard approaches such as androgen deprivation therapy (ADT), taxane-based chemotherapy, radiotherapy, and targeted therapies such as tyrosine kinase inhibitors (TKI) and poly ADP ribose polymerase (PARP) inhibitors. Here, we will review promising immunotherapies in development and ongoing trials for metastatic castration-resistant prostate cancer (mCRPC). These novel trials will build on past experiences and promise to usher a new era to treat patients with mCRPC.

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

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

A novel GPCR target in correlation with androgen deprivation therapy for prostate cancer drug discovery

Most prostate carcinomas require androgen stimulation to grow, and for nearly 70 years, androgen ablation therapy has been one of the central therapeutic strategies against advanced prostate cancer. Although most tumours initially respond to this therapy, some will be acquired resistant and progress to metastatic castration-resistant (mCRPC) disease which clinically tends to progress more rapidly than earlier disease manifestations. The underlying molecular biology of mCRPC is highly complex, and numerous mechanisms have been proposed that promote and retain androgen independence. In various clinical and preclinical data explored, the nature of intracellular signalling pathways mediating mitogenic acquired resistant effects of GPCRs in prostate cancer is poorly defined. G-protein-coupled receptor kinase 2 (GRK2) contributes to the modulation of basic cellular functions-such as cell proliferation, survival or motility-and is involved in metabolic homeostasis, inflammation or angiogenic processes. Moreover, altered GRK2 levels are starting to be reported in different tumoural contexts and shown to promote breast tumourigenesis or to trigger the tumoural angiogenic switch. Thus, we are exploring recent findings that present unexpected opportunities to interfere with major tumourigenic signals by manipulating GPCR-mediated pathways.

A Comprehensive Review of Pharmaceutical and Surgical Interventions of Prostate Cancer

As the second most common cause of death amongst men in the United States, prostate cancer is a type of cancer that is known to develop and originate in the prostate gland. The main function of the prostate gland is to produce seminal fluid in which the sperm bathes. The seminal fluids are necessary for allowing the sperm to move easily through the urethra and also allows successful fertilization by providing an alkaline environment for the sperm in the acidic nature of the vagina. The seminal vesicles are two smaller glands that are attached to either side of the prostate gland and in radical prostatectomies, can get removed. In the event that the seminal vesicles are removed during a radical prostatectomy, the individual is unable to produce any seminal fluids and thus, becoming infertile. Prostate cancer is most commonly seen in patients over the age of 66 years, however, in the presence of predisposing risk factors, may occur as early as in the late 40s. Certain risk factors may speed the presentation of prostate cancer in individuals and thus, mandatory screening is recommended around the age of 45. If no risk factors are present, screening is recommended to begin after the age of 50 years. Screening for prostate cancer is focused on looking for prostate-specific antigen (PSA) in a blood test, though this may not be the most reliable method. The method of diagnosis stems from further testing done following an abnormal PSA test. A digital rectal examination and ultrasonography may also be used to assist with the diagnosis of prostate cancer. Though there are several different types of pharmaceutical interventions currently present in the eradication of prostate cancer, with androgen deprivation therapy being the most commonly used, surgical interventions may be utilized to completely resect cancer from an individual. Different radical prostatectomies are used; the appropriate approach utilized is dependent on the extensiveness of cancer and the type of cancer that is present.

[LHRH analogs in adjuvant endocrine therapy for pre-menopausal localized breast cancers: Ending the controversy for novel guidelines?]

Endocrine treatment represents the cornerstone of endocrine-sensitive pre-menopausal early breast cancer. The estrogen blockade plays a leading role in the therapeutic management with surgery, radiotherapy and selective antiestrogen treatment. For several years, selective estrogen receptor modulators, such as tamoxifen, have revolutionized medical care of hormone receptors-positive breast cancer and have conquered the therapeutic arsenal while becoming the gold standard of treatment. Other combinations associating the ovarian function suppression using LHRH agonists with tamoxifen or aromatase inhibitors have been recently investigated, leading to mitigated opinions regarding the clinical benefit of these associations. We propose here a comprehensive overview on existing data and their actualization concerning LHRH analogues, whilst emphasizing benefit-risk balance for this targeted population.

Bone health during endocrine therapy for cancer

Preservation of bone health remains a long-term clinical challenge in patients with breast and prostate cancer. Osteoporosis, defined by a loss of bone mass and microarchitecture, often results in fragility fractures that are typically associated with a high socioeconomic burden. Endocrine therapy, a mainstay treatment in the management of patients with hormone-sensitive breast and prostate cancer in the adjuvant setting, commonly exerts adverse effects on the musculoskeletal system and is associated with an increased risk of osteoporosis and fractures. Adjuvant use of gonadotropin-releasing hormone analogues, which can also be used in metastatic disease, in combination with tamoxifen in premenopausal women, and aromatase inhibitors in postmenopausal women with hormone-sensitive breast cancer, causes rapid bone loss and fragility fractures. By contrast, selective oestrogen receptor modulators, such as tamoxifen, have bone-protective effects in postmenopausal women. In men with castration-sensitive prostate cancer, androgen deprivation is achieved with drugs that lower gonadotropin levels, and these drugs can be combined with androgen receptor antagonists. These therapies induce a high bone turnover with rapid bone loss that is reminiscent of the changes occurring in early menopause and result in an increased risk of fracture. In this Review, we describe how adjuvant endocrine therapies of breast and prostate cancer impair bone health and outline evidence from randomised controlled trials of strategies to reduce risk of fracture.

Management of Recurrent Ischemic Priapism 2014: A Complex Condition with Devastating Consequences

INTRODUCTION

The management of recurrent ischemic priapism (RIP) is not clearly defined. Given the rarity of this condition, most treatment options are supported at best by level 3 or 4 evidence.

AIM

In this article, we review the current literature regarding the pathophysiology and management of RIP and discuss the risks and benefits associated with each option, which includes ketoconazole (KTZ), 5-α-reductase inhibitors and other hormonal therapies, phosphodiesterase type 5 (PDE5) inhibitors, intracavernosal sympathomimetic injection, oral sympathomimetic agents, and other investigational therapies.

METHODS

A comprehensive literature review was performed regarding the management options for RIP.

MAIN OUTCOME MEASURE

To examine the pathophysiology of RIP and evaluate the treatment options.

RESULTS

Multiple agents have been investigated to manage RIP. KTZ, finasteride, anti-androgens, gonadotropin-releasing hormone agonists, and estrogen have been shown to be effective in several reports, though some of these agents may have significant hormonal side effects. PDE5 inhibitors currently appear to be well tolerated in this patient population, though evidence of its efficacy is limited. Intracavernosal α-agonist therapy may be used to treat episodes of priapism after they occur. Very limited data suggest terbutaline, oral α-agonists, digoxin, hydroxyurea, and gabapentin may have a role in RIP management.

CONCLUSIONS

An ideal management strategy for RIP should focus on prevention of priapic episodes using an effective, well-tolerated, cost-effective medication. We currently have several proposed options, with varying efficacy rates and side effect profiles. While significant advancements in our understanding and management of stuttering priapism have been made within the past few years, clearly continuing research and clinical studies are needed to guide our management of this disease process. Hoeh MP and Levine LA. Management of recurrent ischemic priapism 2014: A complex condition with devastating consequences. Sex Med Rev 2015;3:24-35.

Comparison of the Efficacy of Two Brands of Triptorelin (Microrelin and Diphereline) in Reducing Prostate-Specific Antigen and Serum Testosterone in Prostate Cancer: A Double-Blinded Randomized Clinical Trial

BACKGROUND

Gonadotropin-releasing hormone (GnRH) agonists initiate androgen deprivation in treating prostate cancer (PC). Triptorelin is a synthetic GnRH and many of its market brands such as Diphereline have been introduced so far.

OBJECTIVES

We compared the efficacy of a sustained-release formulation of Triptorelin (Microrelin), domestically produced in Iran, and compared it with Diphereline in a double-blinded randomized clinical trial.

PATIENTS AND METHODS

Patients were randomly assigned to Group A (Microrelin S.R. 3.75 mg, Pooyesh Darou, Iran) and Group B (Diphereline S.R. 3.75 mg, IPSEN, France). Each patient received monthly intramuscular injections. Prostate-specific antigen (PSA) and circulatory testosterone were measured at baseline and after one, 3, and 6 months.

RESULTS

Each group contained 40 patients. In Group A, PSA was reduced from 75.78 ± 72.43 ng/mL to 1.93 ± 1.40 ng/mL after 6 months and testosterone was reduced from 3.50 ± 1.12 nmol/L to 0.81 ± 0.05 nmol/L. There was no significant difference between the efficacy of Microrelin and Diphereline. Two patients in the Microrelin Group and one patient in the Diphereline Group failed to reach medical castration (testosterone < 1.7 nmol/L), which illustrates that the power of Microrelin and Dipherelin in initiating medical castration is about 95% and 97.5%, respectively.

CONCLUSIONS

Our study showed that Microrelin is as effective as Diphereline in reducing PSA and testosterone and can be recommended to initiate medical castration in patients with PC.

Evaluation of the Biological Properties and the Enzymatic Stability of Glycosylated Luteinizing Hormone-Releasing Hormone Analogs

The enzymatic stability, antitumor activity, and gonadotropin stimulatory effects of glycosylated luteinizing hormone-releasing hormone (LHRH) analogs were investigated in this study. Conjugation of carbohydrate units, including lactose (Lac), glucose (GS), and galactose (Gal) to LHRH peptide protected the peptide from proteolytic degradation and increased the peptides' half-lives in human plasma, rat kidney membrane enzymes, and liver homogenate markedly. Among all seven modified analogs, compound 1 (Lac-[Q(1)][w(6)]LHRH) and compound 6 (GS(4)-[w(6)]LHRH) were stable in human plasma during 4 h of experiment. The half-lives of compounds 1 and 6 improved significantly in kidney membrane enzymes (from 3 min for LHRH to 68 and 103 min, respectively). The major cleavage sites for most of the glycosylated compounds were found to be at Trp(3)-Ser(4) and Ser(4)-Tyr(5) in compounds 1-5. Compound 6 was hydrolyzed at Ser(4)-Tyr(5) and the sugar conjugation site. The antiproliferative activity of the glycopeptides was evaluated on LHRH receptor-positive prostate cancer cells. The glycosylated LHRH derivatives had a significant growth inhibitory effect on the LNCaP cells after a 48-h treatment. It was demonstrated that compound 1 significantly increased the release of luteinizing hormone (LH) at 5 and 10 nM concentrations and compound 5 (GS-[Q(1)]LHRH) stimulated the release of follicle-stimulating hormone (FSH) at 5 nM concentration in dispersed rat pituitary cells (p < 0.05). In our studies, compound 1-bearing lactose and D-Trp was the most stable and active and is a promising candidate for future preclinical investigations in terms of in vitro biological activity and metabolic stability.

Novel peptidomimetics related to gonadotropin-releasing hormone (GnRH)

Novel GnRH I and II analogues were designed and synthesized by Solid Phase Peptides Synthesis (SPPS), since GnRH has antiproliferative properties, but poor metabolic stability.

Novel agents in the management of castration resistant prostate cancer

Prostate cancer (PCa) is a leading cause of cancer mortality in men and despite high cure rates with surgery and/or radiation, 30-40% of patients will eventually develop advanced disease. Androgen deprivation is the first line therapy for standard of care for men with advanced disease. Eventually however all men will progress to castration-resistant prostate cancer (CRPC). Insight into the molecular mechanisms of androgen resistance has led to the development of alternative novel hormonal agents. Newer hormonal agents such as abiraterone, enzalutamide and TOK-001; and the first cancer vaccine, Sipuleucel T have been approved for use in men with CRPC. The recognition of the importance of bone health and morbidity associated with skeletal related events has led to the introduction of the receptor activator of nuclear factor kappa-B-ligand inhibitor denosumab. Other molecularly targeted therapies have shown promise in pre-clinical studies, but this has not consistently translated into clinical efficacy. It is increasingly evident that CRPC is a heterogeneous disease and an individualized approach directed at identifying primary involvement of specific pathways could maximize the benefit from targeted therapies. This review focuses on targeted therapy for PCa with special emphasis on therapies that have been Food and Drug Administration approved for use in men with CRPC.

Molecular mechanisms of gonadotropin-releasing hormone signaling: integrating cyclic nucleotides into the network

Gonadotropin-releasing hormone (GnRH) is the primary regulator of mammalian reproductive function in both males and females. It acts via G-protein coupled receptors on gonadotropes to stimulate synthesis and secretion of the gonadotropin hormones luteinizing hormone and follicle-stimulating hormone. These receptors couple primarily via G-proteins of the Gq/ll family, driving activation of phospholipases C and mediating GnRH effects on gonadotropin synthesis and secretion. There is also good evidence that GnRH causes activation of other heterotrimeric G-proteins (Gs and Gi) with consequent effects on cyclic AMP production, as well as for effects on the soluble and particulate guanylyl cyclases that generate cGMP. Here we provide an overview of these pathways. We emphasize mechanisms underpinning pulsatile hormone signaling and the possible interplay of GnRH and autocrine or paracrine regulatory mechanisms in control of cyclic nucleotide signaling.

Preferred treatment frequency in patients receiving androgen deprivation therapy for advanced prostate cancer

OBJECTIVE

The aim of this study was to assess patient preference regarding the length of treatment intervals of androgen deprivation therapy (ADT) with gonadotropin-releasing hormone agonists for prostate cancer.

MATERIAL AND METHODS

The study was conducted as a questionnaire-based, cross-sectional study at a large university hospital. A specific questionnaire was developed based on current literature, clinical experience and a pilot phase of the study. The primary endpoint was preferred treatment frequency. Secondary outcome measures included reasons for preferred treatment frequency, treatment satisfaction and side-effects. Overall, 238 men receiving ADT for prostate cancer were presented with the questionnaire between September 2011 and May 2012. Descriptive statistics, the chi-squared test and multiple regression were used for analyses.

RESULTS

In total, 176 questionnaires (74%) were available for analysis. A total of 38.1% of participants preferred frequent treatment ("Every month", "Every third month"), 32.4% preferred infrequent treatment ("Every sixth month", "Every twelfth month") and 29.6% stated that length of the treatment intervals made no difference (p = 0.37). Patients with disease progression were most likely to prefer frequent treatment (odds ratio 4.4, 95% confidence interval 1.9-10.4). Overall, 84.1% were satisfied with treatment while one patient (0.6%) was dissatisfied. Nine per cent indicated severe side-effects.

CONCLUSIONS

Less frequent ADT treatment may help to lower the pressure on healthcare systems and may be of benefit for a large group of patients. However, it cannot be prescribed blindly without possibly affecting patient satisfaction. The choice of treatment intervals should be made in collaboration between the physician and the patient.

Gonadotrophin-releasing hormone (GnRH) and GnRH agonists: mechanisms of action

The hypothalamic decapeptide gonadotrophin-releasing hormone (GnRH) binds to specific receptors on pituitary gonadotrophs. These receptors belong to the family of G protein-coupled receptors. Their activation leads to phosphoinositide breakdown with generation of inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) and diacylglycerol. These second messengers initiate Ca2+ release from intracellular stores and activation of protein kinase C, both of which are important for gonadotrophin secretion and synthesis. Prolonged activation of GnRH receptors by GnRH leads to desensitization and consequently to suppressed gonadotrophin secretion. This is the primary mechanism of action of agonistic GnRH analogues. By contrast, GnRH antagonists compete with GnRH for receptors on gonadotroph cell membranes, inhibit GnRH-induced signal transduction and consequently gonadotrophin secretion. These compounds are free of agonistic actions, which might be beneficial in certain clinical applications.

Influence of androgen deprivation therapy on choline PET/CT in recurrent prostate cancer

PURPOSE

Recurrent prostate cancer is usually treated by combining radiotherapy and androgen deprivation therapy. To stage the cancer, choline positron emission tomography (PET)/CT can be performed. It is generally thought that androgen deprivation therapy does not influence choline PET/CT. In this article we focus on the molecular backgrounds of choline and androgens, and the results of preclinical and clinical studies performed using PET/CT.

METHODS

Using PubMed, we looked for the relevant articles about androgen deprivation therapy and choline PET/CT.

RESULTS

During ADT, a tendency of decreased uptake of choline in prostate cancer was observed, in particular in hormone-naïve patients.

CONCLUSION

We conclude that in order to prevent false-negative choline PET/CT scans androgen deprivation should be withheld prior to scanning, especially in hormone-naïve patients.

Two innovative pharmaceutical forms of leuprorelin: results from 818 patients with advanced prostate cancer

OBJECTIVES

This study set out to examine the efficacy and tolerability of two innovative implant forms of leuprorelin acetate in men with advanced hormone-dependent prostate cancer in everyday clinical practice.

METHODS

Data were collected from 818 patients (from 273 centers across Germany) who were pretreated with slow-release luteinizing hormone-releasing hormone (LHRH) agonist formulations and who were about to be switched to the leuprorelin implants. Patients received three injections of 1- or 3-month leuprorelin implant and physicians were asked to complete a case report form specific to each of the three clinic visits. Documented parameters included laboratory measurements, such as testosterone and prostate-specific antigen (PSA) levels, adverse events, and patient- and physician-rated assessments of the therapy.

RESULTS

Compared with baseline, a significant decrease in both testosterone and PSA levels were measured after the first and second injections of leuprorelin implant. These results were confirmed for both the 1-month and 3-month implants in separate analyses. Switching, without treatment interruption, from Trenantone® (Takeda Pharma GmBH, Aachen, Germany) to the leuprorelin implant resulted in a significant decrease in the mean serum testosterone concentrations (P < 0.05) and a nonsignificant increase in the proportion of patients reaching castrate testosterone levels, while the number of patients with PSA values ≤ 4 ng/mL significantly increased (P = 0.045). Similar results were obtained for patients previously treated with goserelin who switched to leuprorelin implant. For 94% of patients, treating physicians rated the efficacy of leuprorelin implant as "very good" or "good." Treatment with leuprorelin implant was well tolerated, with only 61 adverse events reported in 42 (5.1%) patients. Patients and physicians rated the tolerability of leuprorelin implant as "very good" or "good" in 95% and 91% of cases, respectively.

CONCLUSIONS

These results confirm the efficacy, tolerability, and ease of use of the leuprorelin implants among a large population of men with advanced, hormone-dependent prostate cancer treated in a clinical practice setting.

Clinical development of two innovative pharmaceutical forms of leuprorelin acetate

OBJECTIVES

Two innovative pharmaceutical forms of leuprorelin acetate have been developed as 1-month and 3-month implants for the treatment of advanced hormone-dependent prostate cancer. These products contain active substance dispersed homogeneously in a biodegradable polymer. Here we present the key results from the clinical development of these slow-release implant formulations of leuprorelin.

METHODS

Two therapeutic studies of the 1-month implant were performed: a randomized, controlled study comparing the leuprorelin implant with leuprorelin prolonged-release microspheres (Enantone) as the active control; and a single-arm study of the leuprorelin implant. For the 3-month implant, four therapeutic studies were performed: a randomized, controlled study comparing the leuprorelin implant with leuprorelin prolonged-release microspheres (Trenantone) as the active control; a single-arm study of the leuprorelin implant; and two long-term studies with the 3-month implant administered twice, either 12 or 16 weeks apart. A pooled analysis of data from the comparator-controlled and single-arm studies of the 3-month implant was also conducted. The main inclusion criterion for all studies was histologically confirmed advanced prostate cancer, with primary endpoints based around successful testosterone suppression (≤0.5 ng/ml).

RESULTS

In the comparator-controlled studies, both implants were as effective as the microspheres for achieving successful testosterone suppression and normalization of prostate-specific antigen (PSA) levels. Data from the single-arm and long-term studies were consistent with those from the comparator-controlled studies. In the pooled analysis, significantly more patients treated with the 3-month implant achieved successful testosterone suppression compared with the comparator (p ≤ 0.01). The safety profile of the implants in the comparator-controlled studies was similar to that of the prolonged-release microsphere formulation, and consistent with that of the luteinizing hormone-releasing hormone agonist class.

CONCLUSIONS

The innovative 1-month and 3-month implants of leuprorelin acetate are at least as effective as leuprorelin acetate prolonged-release microspheres for achieving successful testosterone suppression and normalization of PSA in men with advanced hormone-dependent prostate cancer, with a comparable safety profile.

Triptorelin in the management of prostate cancer

Among the therapies to achieve medical castration, gonadotropin-releasing hormone (GnRH) agonists have better safety profiles than estrogens and anti-androgens. In addition, slow-release formulations of GnRH agonists offer patients flexibility, improve quality of life and eventually reduce cost. To illustrate the role of medical castration in prostate cancer, this paper reviews data on the GnRH agonist triptorelin long-duration and shorter-duration formulations. A similar proportion of patients achieved and maintained castration levels of serum testosterone (≤50 ng/dl) with all triptorelin formulations. Moreover, using a stricter definition of medical castration (serum testosterone <20 ng/dl), castration was maintained in >90% of patients with the 6-month triptorelin formulation. The new formulation was also well-tolerated, whilst being more convenient for patients. This short review assesses the role of this GnRH agonist in the treatment of prostate cancer.

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

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

Hormonal therapy in breast cancer: a model disease for the personalization of cancer care

The treatment of breast cancer is driven by subtype classification, of which the assessment of hormone receptor status is one of the important determinants of therapy. The use of hormonal therapy to treat estrogen-receptor positive breast cancer has been studied for over a century and is one of the well-described uses of personalized medicine. In this review, we will describe the classification of hormone receptor status and the various endocrine treatment strategies. Opportunities for personalization of care are illustrated.

Dutasteride for the treatment of prostate-related conditions

INTRODUCTION

A variety of pharmaceuticals have been developed directed at mitigating the symptoms associated with benign prostatic hypertrophy (BPH) and have also been evaluated for their potential role in prevention and treatment of prostate cancer. One such agent is dutasteride , a non-selective inhibitor of 5α-reductase, an enzyme responsible for conversion of testosterone to a more potent androgen dihydrotestosterone (DHT).

AREAS COVERED

This review will cover the safety profile of dutasteride when it is used in the treatment of prostate-related conditions, specifically looking at the pivotal clinical trials on this drug.

EXPERT OPINION

Dutasteride has proved to be a safe and efficacious treatment for symptoms related to BPH. The primary safety concern relates to the increased incidence of high-grade prostate cancer seen in men treated with dutasteride in the setting of prostate cancer prevention. Dutasteride has a role as an adjunct in the treatment of prostate cancer; however, this is an area still under active investigation. It is not recommended for use in prostate cancer prevention given the increased risk of high-grade cancers.

Cost-utility analysis of adjuvant goserelin (Zoladex) and adjuvant chemotherapy in premenopausal women with breast cancer

Background

Increased health care costs have made it incumbent on health-care facilities and physicians to demonstrate both clinical and cost efficacy when recommending treatments. Though studies have examined the cost-effectiveness of adjuvant goserelin with radiotherapy for locally advanced prostate cancer, few have compared the cost-effectiveness of adjuvant goserelin to adjuvant chemotherapy alone in premenopausal breast cancer.

Methods

In this retrospective study at one hospital, the records of 152 patients with stage Ia to IIIa ER + breast cancer who received goserelin or chemotherapy were reviewed. Survival analysis was assessed by the Kaplan-Meier method. Patients were interviewed to evaluate their quality of life using the European Organization for Research and Treatment Quality of Life questionnaire (EORTC-QLQ-C30, version 4.0), and to obtain the utility value by the standard gamble (SG) and visual scale (VS) methods. Total medical cost was assessed from the (National Health Insurance) NHI payer's perspective.

Results

Survival at 11 years was significantly better in the groserelin group (P < 0.0012). The lifetime lost was lower in the goserelin group (42 months vs. 66 months). The quality adjusted survival (QAS) of patients who received goserelin was longer (122.5 ± 6.3 vs. 112.2 ± 6.7 months). Total expenses of goserelin were more than cyclophosphamide, methotrexate, 5-fluorouracil (CMF) or 5-fluorouracil, epirubicin, cyclophosphamide (FEC) chemotherapy regimes, but less than docetaxel, epirubicin (TE) or docetaxel, epirubicin, cyclophosphamide (TEC) regimes. The quality-adjusted life-year was higher in the goserelin group.

Conclusions

Goserelin therapy results in better survival and higher utility-weighted life-years, and is more cost-effective than TC or TEC chemotherapy.

Use of androgen deprivation therapy in prostate cancer: indications and prevalence

Androgens play a prominent role in the development, maintenance and progression of prostate cancer. The introduction of androgen deprivation therapies into the treatment paradigm for prostate cancer patients has resulted in a wide variety of benefits ranging from a survival advantage for those with clinically localized or locally advanced disease, to improvements in symptom control for patients with advanced disease. Controversies remain, however, surrounding the optimal timing, duration and schedule of these hormonal approaches. Newer hormonal manipulations such as abiraterone acetate have also been investigated and will broaden treatment options for men with prostate cancer. This review highlights the various androgen-directed treatment options available to men with prostate cancer, their specific indications and the evidence supporting each approach, as well as patterns of use of hormonal therapies.

Silencing of the GnRH type 1 receptor blocks the antiproliferative effect of the GnRH agonist, leuprolide, on the androgen-independent prostate cancer cell line DU145

This study investigated the mechanism of action of a gonadotropin-releasing hormone (GnRH) agonist, leuprolide, on proliferation of the hormone-refractory prostate cancer cell line DU145, transfected with short hairpin RNA (shRNA), to reduce expression of the GNRHR1 gene (which encodes the GnRH type 1 receptor). DU145 cell proliferation in the presence of leuprolide (10(-9) and 10(-7) M) or control medium was measured before and after GnRHR1 knockdown. Reverse transcription-polymerase chain reaction and Western blot analysis were used to measure the degree of GNRHR1 silencing. DU145 cells treated with leuprolide (10(-9) and 10(-7) M) showed significant growth inhibition compared with control-treated DU145 cells. Transfection with GNRHR1 -shRNA significantly decreased GNRHR1 expression at 48 h. DU145 cells transfected with silencing GNRHR1 -shRNA showed normal growth patterns; however, there was no significant inhibition of proliferation of DU145 cells transfected with GNRHR1 -shRNA compared with cells transfected with control-shRNA in response to leuprolide. These data demonstrated that the antiproliferative effect of leuprolide was mediated by the GnRHR1.

The timing and extent of androgen deprivation therapy for prostate cancer: weighing the clinical evidence

Androgen deprivation therapy (ADT) is an effective means of palliating symptoms of prostate cancer but is associated with significant toxicities that increase with treatment duration. Primary ADT in men with localized disease provides no survival advantage. Neoadjuvant ADT, when combined with external beam radiation, improves survival for men with locally advanced disease. Immediate adjuvant androgen deprivation does not seem to benefit most men undergoing radical prostatectomy. No evidence supports combined androgen blockade or monotherapy with nonsteroidal antiandrogens for locally advanced prostate cancer. ADT with orchiectomy or gonadotropin-releasing hormone agonists or antagonists is standard care for men with metastatic prostate cancer.

Androgen deprivation therapy through bilateral orchiectomy: increased metabolic risks

Prostate cancer is one of the most common malignancies in men. Previous research has determined that androgen deprivation therapy (ADT) may be accompanied by an unfavourable metabolic profile. In this prospective study, 133 men were recruited, including 46 prostate cancer patients who had undergone bilateral orchiectomy and been on flutamide (the ADT group), 37 men with prostate cancer who had undergone radical prostatectomy (the non-ADT group) and 50 normal control subjects (the control group). All subjects were followed for at least 12 months. From baseline to 3 months, men in the ADT group had increased levels of fasting serum insulin and low-density lipoprotein compared to the other two groups (P<0.05). No obvious changes were found in the other parameters (P>0.05). After 12 months, men in the ADT group had increased levels of waist circumference, fasting serum insulin and glucose, total cholesterol, high-density lipoprotein and low-density lipoprotein compared to the other two groups (P<0.05). Additionally, the morbidity rate of metabolic syndrome in the ADT group was higher (P<0.05) compared to the other two groups. ADT through surgical castration for men with prostate cancer may be associated with unfavourable metabolic changes. The benefits of the therapy should be balanced prudently against these risks.

Dual targeting of tumor and endothelial cells by gonadotropin-releasing hormone agonists to reduce melanoma angiogenesis

We showed previously that GnRH receptors are expressed in melanoma cells; their activation reduces cell growth and metastatic behavior. Here, we investigated whether GnRH agonists might affect the expression of genes involved in melanoma progression. By genome-wide transcriptomic and real-time PCR analysis, we first observed that GnRH agonists decrease the expression of the pro-angiogenic factor vascular endothelial growth factor (VEGF) (all isoforms) in BLM melanoma cells. Then, we demonstrated that GnRH agonists specifically decrease the expression of the VEGF165 isoform as well as its secretion from BLM cells. These data suggested that activation of GnRH receptors might reduce the pro-angiogenic behavior of melanoma cells. To verify this hypothesis, we treated BLM cells with a GnRH agonist; the conditioned medium from these cells was tested to assess its capability to stimulate human umbilical vein endothelial cell (HUVEC) motility. The migration of HUVECs towards the conditioned medium of GnRH agonist-treated BLM cells was significantly lower than the migration of HUVECs toward the conditioned medium of untreated cells. Thus, GnRH agonists reduce the pro-angiogenic behavior of melanoma cells through a decreased production of bioactive VEGF. We then found that GnRH receptors are also expressed on HUVECs and that GnRH agonists reduce their ability to proliferate and to form capillary-like tubes when stimulated by VEGF. These findings suggest that GnRH agonists exert an anti-angiogenic activity indirectly by decreasing VEGF secretion from tumor cells and directly by counteracting the pro-angiogenic activity of the growth factor. These data might lead to the development of novel targeted approaches for melanoma.

Adjuvant endocrine therapy for premenopausal women with breast cancer

AIMS

Endocrine therapy is a pivotal treatment for women with hormone-receptor positive breast cancer. In premenopausal women, endocrine therapy primarily consists of tamoxifen and ovarian suppressive strategies. Younger women experience improvements in the risks of relapse or death from breast cancer with the use of chemotherapy as well, with part of this benefit explained by resultant premature amenorrhea. Unfortunately despite a centuries worth of clinical trials, the most efficacious combination of hormonal therapies and chemotherapy has yet to be determined. This paper serves as a comprehensive review of the substantial data in the adjuvant treatment of premenopausal, hormone receptor-positive women with breast cancer.

METHODS AND RESULTS

PubMed and American Society of Clinical Oncology (ASCO) Proceedings searches from 1896 to present were performed. All of the trials examining the role of ovarian suppression and tamoxifen with and without chemotherapy in premenopausal women were included. The current data suggests that endocrine therapy can be an important alternative to chemotherapy in select patient populations, and improvements in outcome are also seen with the combination of hormonal and chemotherapy strategies in other populations. A majority of the trials examined did not use what is considered to be current standards of care regarding chemotherapy regimens and durations of adjuvant hormonal therapy. Many unanswered questions remain particularly regarding the combined use of ovarian suppression and tamoxifen in women who are also receiving chemotherapy.

CONCLUSION

There is a persistent need to define optimal endocrine therapy in premenopasusal women with hormone-receptor positive breast cancer. Contemporaneous trials, such as the SOFT trial will provide direction, and additional biomarker and pharmacogenomic data will further supplement individualized patient decision making.

Histamine in the nervous system

Histamine is a transmitter in the nervous system and a signaling molecule in the gut, the skin, and the immune system. Histaminergic neurons in mammalian brain are located exclusively in the tuberomamillary nucleus of the posterior hypothalamus and send their axons all over the central nervous system. Active solely during waking, they maintain wakefulness and attention. Three of the four known histamine receptors and binding to glutamate NMDA receptors serve multiple functions in the brain, particularly control of excitability and plasticity. H1 and H2 receptor-mediated actions are mostly excitatory; H3 receptors act as inhibitory auto- and heteroreceptors. Mutual interactions with other transmitter systems form a network that links basic homeostatic and higher brain functions, including sleep-wake regulation, circadian and feeding rhythms, immunity, learning, and memory in health and disease.