Hypothalamic Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH)-Regulating Hormone: Structure, Physiology, and Clinical Studies**The work described here has been supported by research grants from the Veterans Administration, United States Public Health Service Grants AM-07467 and AM-09094, and the Population Council, New York, N.Y.††This paper was presented at the Twenty-Seventh Annual Meeting of the American Fertility Society, New Orleans, Louisiana, March 25–27, 1971

Pharmacokinetic considerations for gonadotropin-releasing hormone agonists and antagonists to treat endometriosis

INTRODUCTION

Endometriosis is a chronic disease characterized by endometriotic cells implanted outside the uterus triggering a chronic inflammatory state. Estradiol stimulates the endometriotic implants, which overexpress estrogen receptor β. Lowering estradiol levels to a range within 40-50 pg/ml allows antagonizing the growth of endometriotic implants and counteracting its-related disabling symptoms.

AREAS COVERED

By blocking the Gonadotropin-Releasing-Hormone (GnRH) receptors, GnRHagonists, peptide GnRHantagonists, non-peptide GnRHantagonists induce hypoestrogenism, due to the suppression of pituitary gonadotropins. This manuscript provides the results of an electronic literature search on pharmacological features of GnRHagonists and GnRHantagonists to treat endometriosis. Hypoestrogenism-dependent side effects can be counteracted by concomitant estrogen and progestin compounds (add-back therapy). GnRHagonists chronic administration induces hypoestrogenism after 10-12 days, since initial administrations stimulate gonadotropin rise (flare-up effect). Peptide GnRHantagonists quickly block GnRH-receptors inducing an immediate hypoestrogenism. Similarly to GnRHagonists, their peptide structure impedes the oral administration. The non-peptide GnRHantagonists have the advantage both of being taken orally and inducing a rapid dose-dependent hypoestrogenism.

EXPERT OPINION

GnRHagonists and peptide GnRHantagonists are effective to treat endometriosis, but require complex ways of administration. Non-peptide GnRHantagonists offer more important prospects in the tailored medical treatment of endometriosis, given their rapid onset of action and their oral way of administration.

Prostate Cancer: A Journey Through Its History and Recent Developments

Prostate cancer is one of the most common diseases among men worldwide and continues to pose a serious threat to health. This review shows the history and the new developments in the management of prostate cancer, with an emphasis on a range of therapeutic approaches, such as hormone therapy, radiation therapy, surgery, and innovative targeted therapeutics. The evolution of these treatments is examined in light of clinical outcomes, patient quality of life, and emerging resistance mechanisms, such as the recently shown vitamin D-based strategies. New developments that have the potential to increase survival rates and reduce side effects are also discussed, including PARP inhibitors (PARPis), immunotherapy, and tailored medication. Additionally, the use of biomarkers and sophisticated imaging methods in therapeutic decision-making is explored, with a focus on how these tools might improve patient care. The absolute necessity for a multidisciplinary approach for improving treatment strategies is becoming more and more apparent as our understanding of the biology of prostate cancer deepens. This approach ensures that patients receive customized medicines that fit their unique profiles. Future avenues of investigation will focus on resolving issues dealing with treatment efficacy and resistance to improve treatment results, ultimately leading to disease cure for prostate cancer patients.

The past and present of prostate cancer and its treatment and diagnostics: A historical review

The prognosis of local prostate cancer has improved drastically during the past 60 years. Similarly, the prognosis in metastatic stage is constantly improving due to a number of new pharmaceuticals introduced over the past 10 years. Previously, only palliative treatments were available for prostate cancer, but today, there are multiple options for treatment with curative intent: robotic-assisted radical prostatectomy, stereotactic radiotherapy and brachytherapy. Additionally, life-prolonging chemotherapeutic and androgen-suppressive treatments, as well as diagnostic imaging and staging, have improved considerably. This review summarizes the history of the treatment and diagnostics of prostate cancer, with a focus on the past 60 years. The aim was to provide a concise and easy-to-read introduction on the matter for all people that work with prostate cancer, as well as for patients. The literature was thoroughly examined covering the period from the earliest traceable records to the latest state-of-the-art studies.

Advances on Hormones and Steroids Determination: A Review of Voltammetric Methods since 2000

This article presents advances in the electrochemical determination of hormones and steroids since 2000. A wide spectrum of techniques and working electrodes have been involved in the reported measurements in order to obtain the lowest possible limits of detection. The voltammetric and polarographic techniques, due to their sensitivity and easiness, could be used as alternatives to other, more complicated, analytical assays. Still, growing interest in designing a new construction of the working electrodes enables us to prepare new measurement procedures and obtain lower limits of detection. A brief description of the measured compounds has been presented, along with a comparison of the obtained results.

Identification and structural elucidation of a new cetrorelix methylene dimer impurity in cetrorelix acetate by using LC-MS/MS

Cetrorelix, a potent third generation of luteinizing hormone releasing hormone (LHRH) antagonist, is a synthetic decapeptide used for treatment of infertility, prostatic hypertrophy and sexual hormone-dependent tumors. The approved drug of cetrorelix (Cetrotide, Asta Medica AG, Frankfurt, Germany.), was used for prevention of premature ovulation in patients undergoing a controlled ovarian stimulation (COS), followed by oocyte pick-up and assisted reproductive techniques, and has been shown safe and effective in controlled ovarian stimulation. Nevertheless, the study of aggregation products of cetrorelix was rarely reported. A simple liquid chromatography mass spectrometry (LC-MS/MS) method was developed for separation, identification and characterization of a new cetrorelix methylene dimer impurity in cetrorelix. The chromatographic separation was achieved on an XSelect Peptide CSH ™C₁₈ column (150 × 4.6 mm, 3.5 μm particle size) using gradient elution with a mobile phase of ammonium formate buffer (pH 3.0, 20 mM), acetonitrile at a flow rate 1.0 mL min^-1, and an ultraviolet detection wavelength of 226 nm. The new cetrorelix methylene dimer impurity was characterized by LC-MS/MS and it characteristic fragment ions were summarized. A simple, fast and accurate method was established for the determination of the molecular weight and structure of the new cetrorelix methylene dimer impurity. In this study, the results showed that the cetrorelix was highly unstable in formaldehyde conditions. In addition, it is proposed that the impact of formaldehyde in the environment on the quality of cetrorelix acetate for Injection should be evaluated during the production process.

A unifying biology of sex steroid-induced apoptosis in prostate and breast cancers

Prostate and breast cancer are the two cancers with the highest incidence in men and women, respectively. Here, we focus on the known biology of acquired resistance to antihormone therapy of prostate and breast cancer and compare laboratory and clinical similarities in the evolution of the disease. Laboratory studies and clinical observations in prostate and breast cancer demonstrate that cell selection pathways occur during acquired resistance to antihormonal therapy. Following sex steroid deprivation, both prostate and breast cancer models show an initial increased acquired sensitivity to the growth potential of sex steroids. Subsequently, prostate and breast cancer cells either become dependent upon the antihormone treatment or grow spontaneously in the absence of hormones. Paradoxically, the physiologic sex steroids now kill a proportion of selected, but vulnerable, resistant tumor cells. The sex steroid receptor complex triggers apoptosis. We draw parallels between acquired resistance in prostate and breast cancer to sex steroid deprivation. Clinical observations and patient trials confirm the veracity of the laboratory studies. We consider therapeutic strategies to increase response rates in clinical trials of metastatic disease that can subsequently be applied as a preemptive salvage adjuvant therapy. The goal of future advances is to enhance response rates and deploy a safe strategy earlier in the treatment plan to save lives. The introduction of a simple evidence-based enhanced adjuvant therapy as a global healthcare strategy has the potential to control recurrence, reduce hospitalization, reduce healthcare costs and maintain a healthier population that contributes to society.

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

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

Evolution of androgen receptor targeted therapy for advanced prostate cancer

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

Potential benefits of intermittent androgen suppression therapy in the treatment of prostate cancer: a systematic review of the literature

CONTEXT

The well-known side-effect profile of androgen-deprivation therapy (ADT) has significant quality-of-life (QoL) implications. Intermittent androgen deprivation (IAD) alternates androgen blockade with treatment cessation to allow hormonal recovery between treatment cycles, thus potentially improving tolerability and QoL.

OBJECTIVE

To evaluate available evidence regarding the efficacy and tolerability of IAD and assess its value in the treatment of prostate cancer (PCa).

EVIDENCE ACQUISITION

Key phase 2/3 clinical trials of IAD in PCa published within the last 10 yr were identified on Medline using the terms prostatic neoplasms [MeSH], intermittent androgen suppression, intermittent hormonal deprivation, intermittent androgen deprivation, and intermittent hormonal therapy. Abstracts from trials reported at 2008-2009 conferences were also included.

EVIDENCE SYNTHESIS

Data from 19 phase 2 studies are discussed with respect to prostate-specific antigen values for treatment suspension/reinitiation, treatment regimens, cycle lengths, testosterone normalisation, and tolerability. Outcome data were promising: Most trials reported an improvement in QoL during the off-therapy periods. Interim data from eight phase 3 trials comparing IAD and continuous androgen deprivation (CAD) support the phase 2 results. IAD generally showed comparable efficacy to CAD with respect to various outcomes, including biochemical progression, progression-free survival, and overall survival. However, IAD was significantly better than CAD with respect to 3-yr risk of progression in one study, and it demonstrated tolerability benefits, particularly with respect to sexual function. Patients most likely to benefit from IAD and factors predictive of poor response are also discussed.

CONCLUSIONS

IAD seems to be as effective as CAD while showing tolerability and QoL advantages, especially recovery of sexual potency; however, there are as yet insufficient data to determine whether IAD has the potential to prevent or reverse the long-term complications associated with ADT.

Effects of the LHRH antagonist Cetrorelix on the brain function in mice

The decapeptide Cetrorelix, an LHRH antagonist, inhibits gonadotropin and sex steroid secretion. Cetrorelix is used for IVF-ET procedures and for the treatment of patients with prostate carcinoma, benign prostatic hyperplasia, endometriosis, leiomyomas and, ovarian cancer. However little is known about the effects of Cetrorelix on the brain function. In the present work the influence of Cetrorelix on different aspects of the brain function was studied following its administration into the lateral brain ventricle in mice. The effects tested included the impairment of the consolidation of a passive avoidance reflex caused by beta-amyloid 25-35, anxiolytic action in the plus-maze, antidepressive action in a forced swimming test and a tail suspension test and open-field behavior. In the passive avoidance test, beta-amyloid 25-35 administered immediately after the learning trial impaired the consolidation of passive avoidance learning. Cetrorelix fully blocked the impairment of the consolidation of passive avoidance learning when given icv 30 min following beta-amyloid 25-35 administration. If beta-amyloid 25-35 and Cetrorelix icv were given simultaneously, the Cetrorelix attenuated, but did not block the action of the beta-amyloid 25-35. Cetrorelix elicited anxiolytic action in the plus-maze, depending on the dose used. In the forced swimming and tail suspension tests, Cetrorelix demonstrated antidepressive-like action. Concerning open-field behavior, Cetrorelix displayed no action on locomotion, rearing or grooming. The results demonstrate that Cetrorelix affects brain function: and is able to correct the impairment of the memory consolidation caused by beta-amyloid 25-35. Cetrorelix also elicits anxiolytic and antidepressive action, but it does not influence the open-field activity. Further experimental work with Cetrorelix is necessary, but the results imply the possible merit of a clinical trial with Cetrorelix in patients with anxiety, depression and Alzheimer's disease.

[Role of hormonotherapy in the treatment of metastatic prostate cancer]

Androgen privation is considered as the referent first line treatment for metastatic prostate cancer. Based on LHRH agonist, different therapeutic schedule included maximum androgenic blockage, intermittent treatment and associations with other drugs like oestrogen leading to possible hormonal manipulations. Since metastasis is confirmed, immediate treatment with continue LHRH agonist is the French Association of Urology (AFU) AFU recommendations treatment for metastatic prostate cancer but intermittent treatment can be considered as an option.

Patient rationale in selecting androgen deprivation (PRISAD): do we give patients what they want?

To assess patient rationale in selecting androgen deprivation, structured telephone interviews were conducted on consecutive patients on androgen deprivation over a 17-year period. The majority of these patients have stable disease that require long-term follow-up with 6-monthly PSA estimations. Synchronous PSA check with depot injections are preferred by majority of patients and longer intervals between the depot administrations are preferable due to perceived less needle pain. This study highlights for the first time patients' preferences for synchronous PSA check with their depot injections and a longer interval between the depot administrations due to perceived less needle pain.

Recurrent gene fusions in prostate cancer

The discovery of recurrent gene fusions in a majority of prostate cancers has important clinical and biological implications in the study of common epithelial tumours. Gene fusion and chromosomal rearrangements were previously thought to be primarily the oncogenic mechanism of haematological malignancies and sarcomas. The prostate cancer gene fusions that have been identified thus far are characterized by 5' genomic regulatory elements, most commonly controlled by androgen, fused to members of the Ets family of transcription factors, leading to the overexpression of oncogenic transcription factors. Ets gene fusions probably define a distinct class of prostate cancer, and this might have a bearing on diagnosis, prognosis and rational therapeutic targeting.

Effect of LHRH-PE40 on target cells via LHRH receptors

OBJECTIVE

To detect the effect and cytotoxicity of luteinizing hormone-releasing hormone-Pseudomonas aeruginosa exotoxin 40 (LHRH-PE40) on target cells using LHRH receptors (LHRHR).

METHODS

The affinity of LHRH-PE40 and LHRH binding to LHRHR on the membrane surface of target cells were measured by enzyme linked immunosorbent assay. Morphological observations with light microscope were used to analyze its receptor pathway, with Spiegelmer, and cytotoxicity. IC(50) values of LHRH-PE40, which caused 50% inhibition of tumor cell growth were evaluated by MTT assay. The target cells were exposed to LHRH-PE40 and its cytotoxicity was analyzed by scanning and transmission electron microscopies, agarose gel electrophoresis, and flow cytometry.

RESULTS

LHRH-PE40 killed target cells by LHRHR pathway. The morphological changes in these cells showed decreased cell size, cytoplasmic membrane blebbing, and chromatin condensation and margination. At a certain concentration and time point, HeLa cells were also induced to undergo programmed cell death.

CONCLUSION

LHRH-PE40 induced target cells apoptosis via LHRHR.

Luteinising hormone-releasing hormone antagonists in prostate cancer therapy

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

Redefining clinically significant castration levels in patients with prostate cancer receiving continuous androgen deprivation therapy

PURPOSE

We determined the testosterone castration level with clinical relevance in patients with prostate cancer on continuous androgen deprivation therapy. Secondary objectives were to analyze the role of associated bicalutamide in breakthrough increases of serum testosterone in these patients and the possible benefit of maximal androgen blockade.

MATERIALS AND METHODS

Serum testosterone was determined 3 times (in 6 months) in 73 patients with nonmetastatic prostate cancer treated with medical castration, 28 (38.4%) of whom also received bicalutamide (maximal androgen blockade). During a mean followup of 51 months (range 12 to 240) 41 (67.1%) events of androgen independent progression were identified, and correlated with breakthrough testosterone increases of 50 ng/dl (classic level) and 20 ng/dl (surgical castration level).

RESULTS

Testosterone was less than 20 ng/dl in all determinations in 32 patients (43.6%). Breakthrough increases between 20 and 50 ng/dl were observed in 23 patients (31.5%), and increases greater than 50 ng/dl were observed in the remaining 18 (24.7%). The lowest testosterone level with a significant impact on survival free of androgen independent progression was 32 ng/dl. Mean survival free of androgen independent progression in patients with breakthrough increases greater than 32 ng/dl was 88 months (95% CI 55-121) while it was 137 months (95% CI 104-170) in those without breakthrough increases (p <0.03). Patients on maximal androgen blockade had an incidence of testosterone increase similar to those receiving monotherapy. However, maximal androgen blockade provided a significantly longer survival free of androgen independent progression in those with breakthrough increases greater than 50 ng/dl.

CONCLUSIONS

In the current report the lowest testosterone castration level with clinical relevance in medically castrated patients with prostate cancer was 32 ng/dl. Breakthrough increases greater than this threshold predicted a lower survival free of androgen independent progression. Maximal androgen blockade might benefit medically castrated cases of prostate cancer with breakthrough increases of more than 50 ng/dl.

Pharmacotherapy for prostate cancer, with emphasis on hormonal treatments

For more than half a century, hormonal therapy has been one of the cornerstones of prostate cancer therapy. However, the position and timing of androgen deprivation therapy is continuously challenged. Nowadays, it is often combined with other types of treatment in a multi-modal approach, especially with radiation therapy. Besides the well-known luteinising hormone-releasing hormone agonists, several developments have been introduced (e.g., luteinising hormone-releasing hormone antagonists or improved depot formulations achieving a better pharmacokinetic slope and lower testosterone levels). Research developments include a better understanding of the different gonadotropin-releasing hormone isoforms, the ligand-independent transformation of the androgen receptor and androgen receptor overexpression in hormone-insensitive disease. Prostate cancer, previously thought to be chemotherapy insensitive, is now treated at the metastatic stage by taxane-based chemotherapies. The combination of hormonal therapy and chemotherapy is currently studied at various stages of the disease, as early as localised or locally advanced prostate cancer. It is very likely that, in the future, pharmacological treatment for prostate cancer will include combination therapies rather than monotherapies. The authors suggest an in-depth re-evaluation of the place of androgen deprivation therapy in prostate cancer.

Drug Insight: clinical use of agonists and antagonists of luteinizing-hormone-releasing hormone

This article reviews the clinical uses of agonists and antagonists of luteinizing-hormone-releasing hormone (LHRH), also known as gonadotropin-releasing hormone. In particular, the state of the art treatment of breast, ovarian and prostate cancer, reproductive disorders, uterine leiomyoma, endometriosis and benign prostatic hypertrophy is reported. Clinical applications of LHRH agonists are based on gradual downregulation of pituitary receptors for LHRH, which leads to inhibition of the secretion of gonadotropins and sex steroids. LHRH antagonists immediately block pituitary LHRH receptors and, therefore, achieve rapid therapeutic effects. LHRH agonists and antagonists can be used to treat uterine leiomyoma and endometriosis; furthermore, both types of LHRH analogs are used to block the secretion of endogenous gonadotropins in ovarian-stimulation programs for assisted reproduction. The preferred primary treatment of patients with advanced, androgen-dependent prostate cancer is based on the periodic administration of depot preparations of LHRH agonists; these agonists can be likewise used to treat estrogen-sensitive breast cancer in premenopausal women. LHRH antagonists have been successfully used to treat prostate cancer and benign prostatic hypertrophy. Since receptors for LHRH are present on a variety of human tumors, (notably breast, prostate, ovarian, endometrial and renal cancers), cytotoxic therapy that targets these tumors with hybrid molecules of LHRH might be possible in the near future. Analogs of LHRH are now a well-established means of treating sex-steroid-dependent, benign and malignant disorders.

Grossesses obtenues par administration pulsatile de GnRH: résultats d'une large étude rétrospective multicentrique

OBJECTIVES

The aim of the present study was to evaluate the efficacy of pulsatile GnRH treatment in a large French cohort of patients with hypogonadotropic hypogonadism.

METHODS

A retrospective study involving all women treated with pulsatile GnRH, over a 3-year period, in 24 French centers. Pregnancy rate and pregnancy outcome were the criteria for evaluation.

RESULTS

The study included 248 women who received a total of 829 treatment cycles. The treatment routes of administration were subcutaneous (56.1% of the patients), intravenous (31.1%), or both (12.7%). The pregnancy rate per treatment cycle was 25%, while the mean number of cycles needed to obtain a pregnancy was 2.8+/-1.7. The miscarriage rate was 8.2% and the multiple pregnancy rates 8.8%. The mean delivery term was 38.4+/-2.4 weeks and the mean birth weight was 3009+/-561 g. No severe ovarian hyperstimulation was recorded. Ovarian cysts occurred in 2.3% of the treatment cycles, local allergies in 1.7%.

CONCLUSION

Our study has shown that pulsatile GnRH treatment was well tolerated, without severe hyperstimulation. It induced a good pregnancy rate with favorable pregnancy outcomes.

Luteinizing hormone-releasing hormone agonists in the treatment of prostate cancer: A review of their discovery, development, and place in therapy

BACKGROUND

Early identification of the biological activity of luteinizing hormone-releasing hormone (LHRH) paved the way for the synthesis of analogues with enhanced potency and biological properties. Early testing in animal models and humans provided insight into the potential clinical uses of these substances, and, within 10 years, LHRH-agonist therapy had become available for use in patients with advanced prostate cancer (PC). Over time, the role of LHRH-agonist therapy has expanded to include use as part of multimodal treatment regimens throughout the course of the disease.

OBJECTIVES

This article reviews the discovery and development of LHRH agonists and summarizes the clinical evidence for their efficacy in PC.

METHODS

Relevant clinical studies were identified through searches of the English-language literature indexed on MEDLINE through May 2006. The main search terms were prostate cancer and LHRH agonist.

RESULTS

Results of the initial therapeutic trials of sustained-release depot formulations of LHRH agonists in patients with PC were reported in the mid-1980s, indicating that these agents were effective and well tolerated in improving clinical symptoms and producing medical castration. Longer-term studies and subsequent meta-analyses of randomized controlled trials in patients with advanced PC found no significant differences in overall survival when single-therapy androgen suppression was achieved through the use of LHRH-agonist therapy or orchiectomy. Randomized trials have reported significant improvements in disease-free and overall survival in patients with locally advanced or high-grade PC treated with LHRH agonists in addition to radiotherapy. Several prospective randomized trials have reported decreases in rates of positive surgical margins with short-term (6 weeks to 4 months) neoadjuvant LHRH-agonist therapy in patients with stage T1 to T3a PC undergoing prostatectomy. Definitive comparisons of immediate and delayed treatment in patients with biochemical relapse have not been reported. However, the results of several studies suggest that immediate LHRH-agonist therapy (or orchiectomy) may improve the course of disease progression and survival. The risks of long-term treatment (eg, osteoporosis; fracture; anabolic loss of muscle mass, with a tendency toward weight gain) must be considered carefully in patients who are likely to receive chronic LHRH-agonist therapy. Intermittent schedules have been developed to reduce the adverse effects associated with LHRH-agonist therapy; some reports support sparing effects on bone and muscle mass and relative improvements in toxicities during off-therapy periods, whereas others have documented continuing decreases in bone mineral density (BMD), with the rate of bone loss highest during the early cycles of therapy. Bisphosphonate therapy has been shown to increase BMD in patients with PC and may therefore be beneficial when overt symptoms of osteopenia or osteoporosis are present.

CONCLUSIONS

LHRH-agonist therapy has been the mainstay of treatment for advanced PC for >20 years. Clinical evidence supports expanding use of these agents at an earlier stage of disease and as part of multimodal regimens that include radiotherapy. There is a need for further study of the efficacy of adjuvant LHRH-agonist therapy along with prostatectomy, in patients with biochemical failure, in intermittent regimens, and in conjunction with cytotoxic therapies in late-stage disease.

Development of prostate cancer treatment: the good news

Prostate cancer is the most commonly diagnosed cancer in American men representing one-third of all new cancer cases each year. This translates into one out of every six American men being diagnosed with prostate cancer over the course of their lifetimes. Over 31,000 of these men die each year from prostate cancer. Before the 1980's, 50% of men were diagnosed with widespread metastatic disease and there were few therapeutic choices for patients. The good news for patients is that, over the last 30 years there have been significant advances in detection and prognostication as well as major improvements in the surgical, radiation, and medical oncological management of prostate cancer. This review describes the evolution of these therapeutic modalities for prostate cancer. This evolution has been driven by the explosion of knowledge concerning cancer in general and in the specific biology of prostate cancer in particular over the last 30 years. This knowledge has been obtained by concentrating human and financial resources in organ specific studies of the prostate. The end result of this effort is that, today, 85% of new prostate cancer cases are diagnosed at local and regional stages and the 5-year relative prostate cancer survival rate has increased by 20% since 1985. In addition, the therapeutic approach to prostate cancer can now be individualized based on the characteristics of the patient's disease. Finally, recent data suggest that the death rate from prostate cancer is decreasing by approximately 4% per year since 1994. Further good news for patients is that new discoveries about the biology of prostate cancer are rapidly being translated into new therapies, a large number of which are currently being tested in clinical trials. Continued allocation of appropriate human and material resources should yield new, more effective therapies for prostate cancer that will further impact patient quality of life and survival in the 21st century.

A benefit-risk assessment of medical treatment for uterine leiomyomas

The growth of a uterine leiomyoma growth stops and regresses after the menopause suggesting that leiomyoma growth is dependent on ovarian steroids. Therefore, estrogen has received much attention as the major factor responsible for the development of uterine leiomyomas, but progesterone also plays an important role in development of this disease. Cytogenetic analyses of resected samples has revealed that about 40 to 50% of leiomyomas show karyotypically detectable chromosomal abnormalities. Gonadotrophin releasing hormone (GnRH) agonists exert their action through the suppression of endogenous gonadotrophins and gonadal steroid secretion. Significant reductions of uterine/leiomyoma volume under GnRH agonist therapy has been reported in several studies. However, the leiomyoma generally returns to its pretreatment volume within a few months after discontinuation of the GnRH agonist. To minimise the adverse effects of hypoestrogenism during GnRH agonist treatment, add back therapy can be used (estrogen-progestin, progestin alone and recently tibolone). Antiprogestins have a potential clinical utility in uterine leiomyomas. Mifepristone is a synthetic steroid with both antiprogesterone and antiglucocorticoid activities, that may have an inhibitory effect on growth of leiomyoma. Danazol is an isoxazole of 17beta-ethinyl testosterone, a synthetic steroid, which has a suppressive effect on sex hormone binding globulin concentrations, resulting in efficacy in the short-term treatment of uterine leiomyomas. Gestrinone is a tri-enic steroid with antiestrogen and antiprogesterone properties and has been shown to reduce uterine volume and stop bleeding. Growth factors play a relevant role on the pathophysiology of uterine leiomyoma and probably the inhibition of the action of growth factors on the myometrium will be the basis for future therapy. A number of agents are under investigation for treating uterine leiomyoma. Agents developed from increasing genetic knowledge of this condition could represent, in the next few years, new trends in the medical treatment of uterine leiomyomas.

A history of prostate cancer treatment

The increased incidence of prostate cancer has led to remarkable changes in diagnosis and treatment over the past century. What were the first ways in which prostate cancer was treated, and how did these evolve into the variety of therapeutic strategies from which patients have to choose today?

Diagnosing and treating small-cell carcinomas of prostatic origin

PURPOSE

Small-cell carcinoma is very aggressive, metastasizes early and often, and does not respond to most chemotherapy regimens. In approximately 50% of cases of prostate cancer, tumors are a combination of small-cell carcinoma and androgen-sensitive adenocarcinoma. It is widely believed that no successful treatment exists for androgen-independent prostate cancer.

METHODS

A 67-year-old man had undergone androgen ablation therapy and radical prostatectomy for prostate cancer followed by bilateral orchiectomy, limited radiation therapy, and unsuccessful chemotherapy for pain-causing metastatic bone disease. Biopsy and immunohistochemical analysis revealed neuroendocrine differentiation of the cancer. The full extent of metastatic disease was assessed successfully using In-111, a somatostatin derivative. Octreotide acetate was used to treat the tumors.

RESULTS

In-111 OctreoScan scintigraphy was more sensitive in the diagnostic demonstration of metastatic foci than was bone scanning. Therapy with the cold somatostatin derivative resulted in a rapid and significant relief of pain with significant tumor shrinkage. The patient remained in remission for at least 10 weeks, when he was lost to follow-up.

CONCLUSIONS

Somatostatin analogs and their radionuclide and cytotoxic derivatives are recommended as adjuvant treatments for prostate carcinoma, especially in those patients who are at high risk for carcinoma recurrence after radical prostatectomy and who have advanced prostate carcinoma at the time of relapse. Because small-cell carcinomas of the prostate and lung are identical, these analogs may be useful in the detection and treatment of these tumors as well.

Hypothalamic hormones and cancer

The use of peptide analogs for the therapy of various cancers is reviewed. Inhibition of the pituitary-gonadal axis forms the basis for oncological applications of luteinizing hormone-releasing hormone (LH-RH) agonists and antagonists, but direct effects on tumors may also play a role. Analogs of somatostatin are likewise used for treatment of various tumors. Radiolabeled somatostatin analogs have been successfully applied for the localization of tumors expressing somatostatin receptors. Studies on the role of tumoral LH-RH, growth hormone-releasing hormone (GH-RH), and bombesin/GRP and their receptors in the proliferation of various tumors are summarized, but the complete elucidation of all the mechanisms involved will require much additional work. Human tumors producing hypothalamic hormones are also discussed. Treatment of many cancers remains a major challenge, but new therapeutic modalities are being developed based on antagonists of GH-RH and bombesin, which inhibit growth factors or their receptors. Other approaches consist of the use of cytotoxic analogs of LH-RH, bombesin, and somatostatin, which can be targeted to receptors for these peptides in various cancers and their metastases. These new classes of peptide analogs should lead to a more effective treatment for various cancers.

Gonadotropin-releasing hormone antagonist: how good is the new hope?

Gonadotropin-releasing hormone agonists have been widely used to prevent luteinizing hormone surges during controlled ovarian stimulation in assisted reproductive technologies. Treatment with gonadotropin-releasing hormone agonists of uterine myoma, endometriosis and some hormone-dependent cancers, such as breast, ovarian, endometrial and prostate cancer, also seems to have a beneficial effect. Gonadotropin-releasing hormone agonists have the disadvantage of inducing an initial stimulatory effect on gonadotropin secretion, necessitating 2-3 weeks before pituitary desensitization is achieved. Gonadotropin-releasing hormone antagonists, on the contrary, cause an immediate inhibition of gonadotropin secretion by competitive blocking of pituitary gonadotropin-releasing hormone receptors. Some advantages of their clinical use in controlled ovarian stimulation have already been demonstrated. Randomized comparative studies are needed to investigate their benefit over gonadotropin-releasing hormone antagonists for myoma and hormone-related disorders.

LH-RH analogues: I. Their impact on reproductive medicine

In the 28 years that have passed since the elucidation of the structure of luteinizing hormone-releasing hormone (LH-RH), diverse clinical applications in the field of reproductive medicine and related fields have been established for agonists of LH-RH, based on inhibition of the pituitary-gonadal axis. Various clinical investigations with agonists of LH-RH in benign gynecologic disorders, polycystic ovary disease (PCOD), in vitro fertilization-embryo transfer (IVF-ET), benign prostatic hypertrophy (BPH), precocious puberty and contraception were reviewed. LH-RH antagonists inhibit LH, follicle-stimulating hormone (FSH), and sex steroid secretion immediately after their administration and thus achieve rapid therapeutic effects. LH-RH antagonists should find applications in the treatment of uterine leiomyomas, endometriosis, and in controlled ovarian stimulation-assisted reproductive techniques (COS-ART), which have been already established for the agonists. Modern LH-RH antagonists such as cetrorelix may prove superior to the agonists in COS-ART and also in the treatment of BPH, but additional studies in these and other areas are needed.

Luteinizing hormone-releasing hormone analogs: their impact on the control of tumorigenesis

The development of the luteinizing hormone-releasing hormone (LH-RH) agonists and antagonists and the principles of their clinical use were reviewed. In the 28 years that have elapsed since the elucidation of the structure of LH-RH, various applications in gynecology, reproductive medicine, and oncology have been established for LH-RH agonists and antagonists. These clinical applications are based on inhibition of the pituitary and the gonads. The advantage of the LH-RH antagonists is due to the fact that they inhibit the secretion of gonadotropins and sex steroids immediately after the first injection and thus achieve rapid therapeutic effects in contrast to the agonists, which require repeated administration. LH-RH antagonists should find applications in the treatment of benign gynecologic disorders and benign prostatic hypertrophy and in assisted reproduction programs. The primary treatment of advanced androgen-dependent prostate cancer is presently based on the use of depot preparations of LH-RH agonists, but antagonists like Cetrorelix already have been tried successfully. Antagonists of LH-RH might be more efficacious than agonists in treatment of patients with breast cancer as well as ovarian and endometrial cancer. Recently, practical cytotoxic analogs of LH-RH that can be targeted to LH-RH receptors on tumors have been synthesized and successfully tested in experimental cancer models. Targeted cytotoxic LH-RH analogs show a great promise for therapy of prostate, breast, and ovarian cancers.

Rational use of agonists and antagonists of luteinizing hormone-releasing hormone (LH-RH) in the treatment of hormone-sensitive neoplasms and gynaecologic conditions

Analogues of luteinizing hormone-releasing hormone (LH-RH) have made possible new approaches to the treatment of some hormone-dependent cancers and diseases and conditions which result from inappropriate sex hormone levels. In the fields of both gynaecology and oncology, the development of sustained delivery depot systems has played a key role in the clinical use of LH-RH agonists and will be also essential for the LH-RH antagonists. Clinical results show that therapy with agonists of LH-RH is the preferred method of treatment for men with advanced prostate cancer. For prostate cancer and other indications, the new LH-RH antagonists such as Cetrorelix may offer an advantage based on the fact that they inhibit LH, FSH and sex-steroid secretion from the start of the administration and thus reduce the time of the onset of therapeutic effects. The use of antagonists would avoid the temporary clinical "flare-up" of the disease which can occur with the agonists in men with prostate cancer. The rapid shrinkage of the prostate and improvement in urinary symptoms obtained with Cetrorelix in men with benign prostatic hyperplasia (BHP) suggests that LH-RH antagonists offer a therapeutic alternative in patients who are considered poor surgical risks. Various experimental and clinical studies suggest that analogues of LH-RH might be useful for treatment of premenopausal women with oestrogen-dependent breast cancer. LH-RH antagonists such as Cetrorelix could be also considered for hormonal therapy of epithelial ovarian cancer which responds only marginally to the agonists, and for treatment of endometrial cancer. Many investigators have reported beneficial effects of LH-RH agonists in the treatment of patients with leiomyomas. LH-RH antagonists also appear to be promising for therapy of uterine leiomyomas, and in addition might be useful for treatment of endometriosis and polycystic ovarian disease (PCOD). LH-RH agonists have been employed in in vitro fertilization and embryo transfer (IVF-ET) programs to prevent a premature rise in LH and various results suggest that the use of antagonist Cetrorelix in assisted reproduction procedures, could be even more advantageous. For most of these indications, the use of sustained release depot preparations will be required.