Antiandrogen monotherapy: a new form of treatment for patients with prostate cancer

Treatment pathways of Japanese prostate cancer patients - A retrospective transition analysis with administrative data

BACKGROUND

Limited availability of real-world data that describe treatment patterns of Japanese prostate cancer (PCA) patients.

METHODS

A biweekly transition analysis of PCA treatment was performed for patients with PCA diagnosis and a specific treatment between 2010 and 2015. To account for different cancer stages, two patient populations were analyzed. The first group consisted of patients on medication for hormone-sensitive prostate cancer (HSPC). The second group is comprised of patients who ended up receiving specific therapy for castration-resistant prostate cancer (CRPC). For each treatment, the average of treatment duration and the portion of patients transitioning to a consecutive treatment was calculated.

RESULTS

We identified 59,626 patients from the Japanese administrative database with a PCA diagnosis and specific treatment. In the first year of our observational study 786 patients commenced a HSPC treatment and 695 received a CRPC specific therapy Among the HSPC group, we found that combination hormonal therapy, comprised of a gonadotrophin releasing hormone agonist or antagonist with an antiandrogen was more common than monotherapy. The results of the CRPC group indicated that chemotherapy administration was for a shorter time period in a real-world setting as compared to published clinical studies.

CONCLUSION

Utilizing a novel method to visualize real-world treatment pathways for PCA patients we found that real treatment pathways are in line with international guidelines.

Design and synthesis of novel bicalutamide and enzalutamide derivatives as antiproliferative agents for the treatment of prostate cancer

Prostate cancer (PC) is one of the major causes of male death worldwide and the development of new and more potent anti-PC compounds is a constant requirement. Among the current treatments, (R)-bicalutamide and enzalutamide are non-steroidal androgen receptor antagonist drugs approved also in the case of castration-resistant forms. Both these drugs present a moderate antiproliferative activity and their use is limited due to the development of resistant mutants of their biological target. Insertion of fluorinated and perfluorinated groups in biologically active compounds is a current trend in medicinal chemistry, applied to improve their efficacy and stability profiles. As a means to obtain such effects, different modifications with perfluoro groups were rationally designed on the bicalutamide and enzalutamide structures, leading to the synthesis of a series of new antiproliferative compounds. Several new analogues displayed improved in vitro activity towards four different prostate cancer cell lines, while maintaining full AR antagonism and therefore representing promising leads for further development. Furthermore, a series of molecular modelling studies were performed on the AR antagonist conformation, providing useful insights on potential protein-ligand interactions.

Clinical outcomes of helical tomotherapy for super-elderly patients with localized and locally advanced prostate cancer: comparison with patients under 80 years of age

We investigated the clinical outcomes of helical tomotherapy in 23 patients aged ≥80 years with localized and locally advanced prostate cancer and compared the results with data from 171 patients under 80 years. All patients received helical tomotherapy in our hospital between September 2009 and October 2012. The median follow-up periods were 35 months in the aged group and 34 months in the younger group. The median prescribed dose in helical tomotherapy was 78 Gy in 39 fractions (range, 72-78 Gy). The 3-year overall survival and biochemical relapse-free rates were 92% and 96% in the aged group and 99.4% and 97.3% in the younger group, respectively. There was no significant difference between the two groups in the biochemical relapse-free rates. The 3-year cumulative incidences of late Grade 2 or higher rectal toxicity and urinary toxicity were 13% and 4.8% in the aged group and 7.0% and 1.2% in the younger group, respectively. There was no significant difference between the aged group and the younger group in the cumulative incidence rates of rectal toxicity or urinary toxicity. No patients exhibited Grade 4 or higher toxicity, and all patients improved with conservative therapy. Helical tomotherapy in super-elderly patients with localized and locally advanced prostate cancer had good biochemical control rates without severe late toxicity. Definitive helical tomotherapy may be the treatment of choice for patients with localized and locally advanced prostate cancer, even in those older than 80 years of age.

Recent discoveries and developments of androgen receptor based therapy for prostate cancer

The main focus of this review is to discuss the discoveries and developments of various therapies for prostate cancer.

The use of dietary supplements to alleviate androgen deprivation therapy side effects during prostate cancer treatment

Prostate cancer (PCa), the most commonly diagnosed cancer and second leading cause of male cancer death in Western societies, is typically androgen-dependent, a characteristic that underlies the rationale of androgen deprivation therapy (ADT). Approximately 90% of patients initially respond to ADT strategies, however many experience side effects including hot flashes, cardiotoxicity, metabolic and musculoskeletal alterations. This review summarizes pre-clinical and clinical studies investigating the ability of dietary supplements to alleviate adverse effects arising from ADT. In particular, we focus on herbal compounds, phytoestrogens, selenium (Se), fatty acids (FA), calcium, and Vitamins D and E. Indeed, there is some evidence that calcium and Vitamin D can prevent the development of osteoporosis during ADT. On the other hand, caution should be taken with the antioxidants Se and Vitamin E until the basis underlying their respective association with type 2 diabetes mellitus and PCa tumor development has been clarified. However, many other promising supplements have not yet been subjected large-scale clinical trials making it difficult to assess their efficacy. Given the demographic trend of increased PCa diagnoses and dependence on ADT as a major therapeutic strategy, further studies are required to objectively evaluate these supplements as adjuvant for PCa patients receiving ADT.

Androgen deprivation therapy impact on quality of life and cardiovascular health, monitoring therapeutic replacement

INTRODUCTION

Androgen deprivation therapy (ADT) is commonly utilized in the management of both localized and advanced adenocarcinoma of the prostate. The use of ADT is associated with several adverse events, physical changes, and development of medical comorbidities/mortality.

AIM

The current article reviews known adverse events associated with ADT as well as treatment options, where available. Current recommendations and guidelines are cited for ongoing monitoring of patients receiving ADT.

METHODS

A PubMed search of topics relating to ADT and adverse outcomes was performed, with select articles highlighted and reviewed based on level of evidence and overall contribution.

MAIN OUTCOME MEASURES

Reported outcomes of studies detailing adverse effects of ADT were reviewed and discussed. Where available, randomized trials and meta-analyses were reported.

RESULTS

ADT may result in several adverse events including decreased libido, erectile dysfunction, vasomotor symptoms, cognitive, psychological and quality of life impairments, weight gain, sarcopenia, increased adiposity, gynecomastia, reduced penile/testicular size, hair changes, periodontal disease, osteoporosis, increased fracture risk, diabetes and insulin resistance, hyperlipidemia, and anemia. The definitive impact of ADT on lipid profiles, cardiovascular morbidity/mortality, and all-cause mortality is currently unknown with available data. Treatment options to reduce ADT-related adverse events include changing to an intermittent treatment schedule, biophysical therapy, counseling, and pharmacotherapy.

CONCLUSIONS

Patients treated with ADT are at increased risk of several adverse events and should be routinely monitored for the development of potentially significant morbidity/mortality. Where appropriate, physicians should reduce known risk factors and counsel patients as to known risks and benefits of therapy.

The role of enzalutamide in the treatment of castration-resistant prostate cancer

Prostate cancer is the most common solid organ cancer affecting the male population. Men with metastatic prostate cancer treated with androgen ablation therapy often respond rapidly, with improvement in bone pain and decreases in serum prostate-specific antigen. However, almost all patients progress to the castration-resistant state and abiraterone acetate was the last treatment available with proven survival benefit. Enzalutamide (formerly MDV3100) is an androgen receptor signaling inhibitor that has been shown to improve survival in men with metastatic castration-resistant prostate cancer previously treated with chemotherapy. In this article we discuss the characteristics of enzalutamide and provide a review of its clinical development.

Improved docking, screening and selectivity prediction for small molecule nuclear receptor modulators using conformational ensembles

Nuclear receptors (NRs) are ligand dependent transcriptional factors and play a key role in reproduction, development, and homeostasis of organism. NRs are potential targets for treatment of cancer and other diseases such as inflammatory diseases, and diabetes. In this study, we present a comprehensive library of pocket conformational ensembles of thirteen human nuclear receptors (NRs), and test the ability of these ensembles to recognize their ligands in virtual screening, as well as predict their binding geometry, functional type, and relative binding affinity. 157 known NR modulators and 66 structures were used as a benchmark. Our pocket ensemble library correctly predicted the ligand binding poses in 94% of the cases. The models were also highly selective for the active ligands in virtual screening, with the areas under the ROC curves ranging from 82 to a remarkable 99%. Using the computationally determined receptor-specific binding energy offsets, we showed that the ensembles can be used for predicting selectivity profiles of NR ligands. Our results evaluate and demonstrate the advantages of using receptor ensembles for compound docking, screening, and profiling.

Heat shock protein 90 (Hsp90) chaperone complex inhibitor, Radicicol, potentiated radiation-induced cell killing in a hormone-sensitive prostate cancer cell line through degradation of the androgen receptor

Until now, there has not been enough information on how androgens or androgen deprivation may influence the response of cancer cells to radiation. In this study, the effect of dihydrotestosterone (DHT) on cellular proliferative activity and radiosensitivity was examined in a hormone-sensitive human prostate cancer cell line, LNCaP. In addition, the study also examined how a heat shock protein 90 (Hsp90) chaperone complex inhibitor modified the effect of DHT on the radiosensitivity of the cells, because binding of the androgen receptor (AR) to Hsp90 is required to maintain the stability and functioning of AR. The hormone-sensitive human prostate cancer cell line, LNCaP, was used. Radicicol was used as one of the known Hsp90 chaperone complex inhibitors, and the cells were incubated in the presence of this compound at a concentration of 500 nM. Cellular radiosensitivity was determined by the clonogenic assay; the changes in the protein expression were examined by Western blotting or immunofluorescence. DHT at a concentration of 1 nM caused enhancement of the proliferative activity and reduction of the radiosensitivity of the cells. Radicicol at a concentration of 500 nM abolished the DHT-induced decrease in cellular radiosensitivity and potentiated the radiation-induced cell killing synergistically. Consistent with the changes in the cellular radiosensitivity, radicicol degraded AR, Raf-1 and HER2/neu via reduced binding of AR to Hsp90, although selective degradation of HER2/neu caused by Herceptin, a monoclonal antibody against HER2, did not affect the cellular radiosensitivity. The results suggest that the Hsp9O chaperone complex may be a potential molecular target for potentiation of radiation-induced cell killing in a hormone-sensitive prostate cancer cell line.

External beam radiotherapy for clinically localized hormone-refractory prostate cancer: clinical significance of Nadir prostate-specific antigen value within 12 months

PURPOSE

To analyze retrospectively the results of external beam radiotherapy for clinically localized hormone-refractory prostate cancer and investigate the clinical significance of nadir prostate-specific antigen (PSA) value within 12 months (nPSA12) as an early estimate of clinical outcomes after radiotherapy.

METHODS AND MATERIALS

Eighty-four patients with localized hormone-refractory prostate cancer treated with external beam radiotherapy were retrospectively reviewed. The total radiation doses ranged from 30 to 76 Gy (median, 66 Gy), and the median follow-up period for all 84 patients was 26.9 months (range, 2.7-77.3 months).

RESULTS

The 3-year actuarial overall survival, progression-free survival (PFS), and local control rates in all 84 patients after radiotherapy were 67%, 61%, and 93%, respectively. Although distant metastases and/or regional lymph node metastases developed in 34 patients (40%) after radiotherapy, local progression was observed in only 5 patients (6%). Of all 84 patients, the median nPSA12 in patients with clinical failure and in patients without clinical failure was 3.1 ng/mL and 0.5 ng/mL, respectively. When dividing patients according to low (<0.5 ng/mL) and high (>or=0.5 ng/mL) nPSA12 levels, the 3-year PFS rate in patients with low nPSA12 and in those with high nPSA12 was 96% and 44%, respectively (p < 0.0001). In univariate analysis, nPSA12 and pretreatment PSA value had a significant impact on PFS, and in multivariate analysis nPSA12 alone was an independent prognostic factor for PFS after radiotherapy.

CONCLUSIONS

External beam radiotherapy had an excellent local control rate for clinically localized hormone-refractory prostate cancer, and nPSA12 was predictive of clinical outcomes after radiotherapy.

Selected endocrine disrupting compounds (vinclozolin, flutamide, ketoconazole and dicofol): effects on survival, occurrence of males, growth, molting and reproduction of Daphnia magna

BACKGROUND, AIM AND SCOPE

Pollution-induced endocrine disruption in vertebrates and invertebrates is a worldwide environmental problem, but relatively little is known about effects of endocrine disrupting compounds (EDCs) in planktonic crustaceans (including Daphnia magna). Aims of the present study were to investigate acute 48 h toxicity and sub-chronic (4-6 days) and chronic (21 days) effects of selected EDCs in D. magna. We have investigated both traditional endpoints as well as other parameters such as sex determination, maturation, molting or embryogenesis in order to evaluate the sensitivity and possible use of these endpoints in ecological risk assessment.

MATERIALS AND METHODS

We have studied effects of four model EDCs (vinclozolin, flutamide, ketoconazole and dicofol) on D. magna using (i) an acute 48 h immobilization assay, (ii) a sub-chronic, 4-6 day assay evaluating development and the sex ratio of neonates, and (iii) a chronic, 21 day assay studying number of neonates, sex of neonates, molting frequency, day of maturation and the growth of maternal organisms.

RESULTS

Acute EC50 values in the 48 h immobilization test were as follows (mg/L): dicofol 0.2, ketoconazole 1.5, flutamide 2.7, vinclozolin >3. Short-term, 4-6 day assays with sublethal concentrations showed that the sex ratio in Daphnia was modulated by vinclozolin (decreased number of neonate males at 1 mg/L) and dicofol (increase in males at 0.1 mg/L). Flutamide (up to 1 mg/L) had no effect on the sex of neonates, but inhibited embryonic development at certain stages during chronic assay, resulting in abortions. Ketoconazole had no significant effects on the studied processes up to 1 mg/L.

DISCUSSION

Sex ratio modulations by some chemicals (vinclozolin and dicofol) corresponded to the known action of these compounds in vertebrates (i.e. anti-androgenicity and anti-oestrogenicity, respectively). Our study revealed that some chemicals known to affect steroid-regulated processes in vertebrates can also affect sublethal endpoints (e.g. embryonic sex determination and/or reproduction) in invertebrates such as D. magna.

CONCLUSIONS

A series of model vertebrate endocrine disrupters affected various sub-chronic and chronic parameters in D. magna including several endpoints that have not been previously studied in detail (such as sex determination in neonates, embryogenesis, molting and maturation). Evaluations of traditional reproduction parameters (obtained from the 21 day chronic assay). as well as the results from a rapid, 4-6 day, sub-chronic assay provide complementary information on non-lethal effects of suspected organic endocrine disrupters.

RECOMMENDATIONS AND PERSPECTIVES

It seems that there are analogies between vertebrates and invertebrates in toxicity mechanisms and in vivo effects of endocrine disruptors. However, general physiological status of organisms may also indirectly affect endpoints that are traditionally considered 'hormone regulated' (especially at higher effective concentrations as observed in this study) and these factors should be carefully considered. Further research of D. magna physiology and comparative studies with various EDCs will help to understand mechanisms of action as well as ecological risks of EDCs in the environment.

Global gene expression profiling of androgen disruption in Qurt strain medaka

Androgen disrupting chemicals (ADCs) are endocrine disrupting chemicals (EDCs) that mimic or antagonize the effect of physiological androgens. Microarray-based detection of altered gene expression can be used as a biomarker of EDC exposure. Therefore, the purpose of this study was to identify and compare gene expression profiles of the androgen 11-ketotestosterone (11-KT), the antiandrogen flutamide (FLU), and the antiandrogenic fungicide vinclozolin (VIN), on Qurt medaka (Oryzias latipes). Biologically effective concentrations for 11-KT (100 microg/L), VIN (100 microg/L), and FLU (1000 microg/L) determined in range-finding studies were used for exposures. The oligonucleotide microarray included 9379 probes for EDC-affected genes, medaka cDNAs, sequences from the medaka genome project, and the UniGene database. We found that treatment with FLU, VIN, and 11-KT caused significant (false discovery rate = 0.01) differential expression of at least 87, 82, and 578 genes, respectively. Two sets of responsive genes are associated to vertebrate sex differentiation and growth, and 50 genes were useful in discriminating between ADC classes. The discriminating capacity was confirmed by a remarkable similarity of the antiandrogenic expression profiles of VIN and FLU, which were distinct from the androgenic profile of 11-KT. Gene expression profiles characterized in this study allow for reliable screening of ADC activity.

Abarelix for injectable suspension: first-in-class gonadotropin-releasing hormone antagonist for prostate cancer

Abarelix, a gonadotropin-releasing hormone antagonist, with its indication for advanced symptomatic prostate cancer, represents the newest category of hormonal therapy introduced in the past 15 years. Results from Phase II and III clinical trials demonstrate the advantages of abarelix over commonly used luteinizing hormone-releasing hormone (LHRH) agonist therapy: abarelix does not cause a surge in serum testosterone that can precipitate a flare phenomenon or worsening of disease, particularly dangerous for patients with metastatic, symptomatic disease, and produces medical castration more quickly. Abarelix was also demonstrated to promptly and substantially reduce follicle-stimulating hormone levels to lower than LHRH agonist. Study results demonstrate effective anticancer responses during extended exposure to abarelix: improvements in pain score and/or analgesic use, improvements in urinary symptoms (including urinary catheter removal) and complete avoidance of bilateral orchiectomy for patients undergoing at least 12 weeks of treatment. In Phase III clinical trials, abarelix demonstrated a similar overall safety profile when compared with LHRH agonist monotherapy, and a superior safety profile when compared with LHRH agonist plus antiandrogen combination therapy. Abarelix patients experienced a greater incidence of immediate-onset systemic allergic reactions as compared with control arms.

Oncolytic herpes simplex virus vector g47delta in combination with androgen ablation for the treatment of human prostate adenocarcinoma

PURPOSE

The use of oncolytic herpes simplex virus type 1 is a promising stategy for cancer treatment. We constructed herpes simplex virus type 1 vector G47Delta by deleting the alpha47 gene and the promoter region of US11 from G207. We now report studies demonstrating the potential of G47Delta as a therapeutic modality for prostate cancer in combination with androgen ablation.

EXPERIMENTAL DESIGN

The cytopathic activities of G47Delta at low multiplicities of infection was tested in human prostate cancer cell lines LNCaP, PC-3, and DU145 in vitro. Two androgen-dependent mouse s.c. tumor models, murine TRAMP and human HONDA, were used to investigate the in vivo efficacy of G47Delta in combination with androgen ablation.

RESULTS

G47Delta at low multiplicities of infection showed more rapid tumor cell killing than G207 in LNCaP and DU145 in vitro and showed a 22-fold higher virus yield in a single-step growth experiment. In vivo, G47Delta treatment resulted in reduced tumor growth of established s.c. TRAMP and HONDA tumors and inhibited the growth of recurrent HONDA tumors that once regressed by androgen ablation therapy. In both TRAMP and HONDA tumor xenografts, the combination therapy of G47Delta with androgen ablation led to significantly enhanced inhibition of the tumor growth and prolonged survival.

CONCLUSIONS

These results suggest that oncolytic virus therapy with G47Delta can be usefully combined with androgen ablation therapy for the treatment of prostate cancer.

Actualización del tratamiento del cáncer de próstata avanzado y de sus complicaciones

Prostate adenocarcinoma is the leading cause of cancer in Spain, among men older than 65. 1,200 new cases out of every 100,000 males are diagnosed with prostate cancer on an annual basis. In the United States, this illness represents the second leading cause of death due to cancer in males. In those patients whose prostate tumors progress after surgery or radiotherapy, or have metastatic disease when diagnosed, a systemic approach in order to improve their quality of life and overall survival is mandatory. First line hormone therapies usually reach a proper control of the tumor maintaining an acceptable quality of life. However, most of these tumors becomes androgen-independent over time and behave as a more aggressive cancer type. In these patients, combination therapy protocols have recently demonstrated a benefit not only in terms of symptoms control and response rates but also in improving survival. In addition, several new molecules are currently under study. The accurate knowledge of the symptoms due to disease spreading as well as treatment's side effects is necessary to provide an appropriate palliative management that contributes to an improvement of the quality of life in advanced prostate cancer patients.

Flutamide administration at 500 mg daily has similar effects on serum testosterone to 750 mg daily

A prior comparison of 750 mg flutamide daily to 500 mg daily with an LHRH analog or orchiectomy showed no difference in effect on prostate specific antigen (PSA). However, any difference was likely masked by hypogonadism from concomitant LHRH analog or orchiectomy. We sought to evaluate different flutamide dosing schedules without this confounding factor. We recruited 50 men with advanced prostate cancer who elected to receive hormonal therapy to be randomized to 1 of 3 flutamide treatment groups: 1) 250 mg once daily, 2) 250 mg twice daily, or 3) 250 mg 3 times daily for 3 months, after which the therapy of their choice was instituted. Serum samples at the initiation of therapy and at the 1- and 3-month time point were assessed for PSA, testosterone, liver function tests, hematology, and renal function. Prostate volume, androgen deficiency symptoms, and a compliance diary were also recorded. Testosterone and PSA levels show a dose-dependent response to flutamide monotherapy. Loss of libido and erectile dysfunction occurred in all 3 treatment groups, with a trend toward worsening sexual function with higher flutamide dosing, but this trend did not reach statistical significance. Prostate volumes decreased by an average of 34.3% in the patients receiving 250 mg flutamide 3 times daily, 27.8% in patients receiving 250 mg flutamide twice daily, and 19.2% in those receiving a once daily dose of 250 mg flutamide. There was a significant difference between the once daily group and the 3 times daily group (P =.047). Flutamide at 500 mg did not result in significant changes in testosterone, PSA, prostate volume, or androgen deficiency symptoms compared to 750 mg daily after 3 months.

Economical impact of orchiectomy for advanced prostate cancer

PURPOSE

To demonstrate the economical impact of surgical castration in comparison to the medical castration for patients with advanced prostate cancer.

MATERIAL AND METHODS

Between January 2001 and December 2001, 32 patients with advanced prostate cancer underwent bilateral sub-capsular orchiectomy at our Hospital. The costs of this procedure were compared to the costs of medical castration with LH-RH analogues.

RESULTS

The costs of the surgical procedure were extremely reduced when compared to published data on the medical treatment. Surgical castration did not have any stronger negative impact on the evolution of these patients when compared to medical castration.

CONCLUSION

Surgical castration is an efficient and low cost treatment for advanced prostate cancer.

Management of recurrent disease after radical prostatectomy

Prostate cancer has undergone a stage migration since the advent of widespread PSA testing, yet still a significant number of men develop PSA recurrence following radical prostatectomy. This causes anxiety to the patient and the urologist. This review examines the clinical significance of biochemical relapse and the role of imaging modalities and anastomotic biopsies. The importance of the radical prostatectomy pathological features and the PSA kinetics in determining the site of recurrence and the best treatment modality is emphasised. The optimal timing and dose of salvage radiotherapy and the role of hormonal therapy is discussed.

Androgen deprivation therapy for prostate cancer: current status and future prospects

Androgens play a major role in promoting the development and progression of prostate cancer. As a result, androgen ablation or blockade of androgen action through the androgen receptor (AR) has been the cornerstone of treatment of advanced prostate cancer. Different strategies involving this hormonal therapy produce a significant clinical response in most of the patients, but most responders eventually lose dependency, resulting in mortality. Thus, whether hormonal therapy contributes to the improvement of overall survival rates, especially in patients with advanced prostate cancer, remains controversial. However, patients with advanced disease clearly have a benefit from androgen deprivation-based treatment for palliating their symptoms and for improving the quality of their lives. In order to improve overall survival, novel treatment strategies that prolong the androgen-dependent state and that are useful for androgen-independent disease based on specific molecular mechanisms need to be identified.

PSA relapse prostate cancer: the importance of tailored therapy

Prostate specific antigen (PSA) is an invaluable tumor marker in the detection of early prostate cancer as well as a predictor of recurrence after treatment of localized disease. Current practice entails the use of factors such as pretherapy grade, stage and PSA, PSA doubling time, nature of previous therapy and patient age and functional status for a treatment recommendation. For a PSA relapse post radical prostatectomy, radiation therapy to the prostatic fossa is a primary therapeutic consideration. With careful patient selection, about 30 to 40% of patients are rendered disease free using this approach. For patients with radiation therapy as the primary treatment for their prostate cancer, salvage prostatectomy can be considered, but is rarely feasible. Systemic therapy with hormones is standard if patients are not candidates for the above mentioned salvage local therapies or if they relapse after exhaustive local therapies. Unfortunately androgen suppressive therapy is unlikely to induce cure, or prolonged remissions in PSA relapse prostate cancer. The strategy of addition of chemotherapy or biologic therapy to androgen suppressive therapy is under active investigation. The goal of this therapy is to make an impact on the time to progression to metastatic prostate cancer and correspondingly decrease prostate cancer related mortality. Preliminary results of studies incorporating early chemotherapy in combination with androgen suppressive therapy are encouraging, with improvement in time to progression and overall survival. The evaluation of biologic agents and agents with better toxicity profiles is ongoing. This is very important to make therapy widely applicable and to enable prolonged administration especially in a disease such as prostate cancer with a relatively long natural history. Strategies of adjuvant and neoadjuvant therapy in locally advanced prostate cancer are exploring the possibility of reducing the chance of PSA relapse by treating micrometastatic disease. This review discusses the current practices in risk stratification and management of PSA relapse prostate cancer. It also highlights the major clinical trials and areas of active investigation in this field.

Cost-effectiveness analysis of bicalutamide (Casodex) for adjuvant treatment of early prostate cancer

OBJECTIVES

To assess the cost-effectiveness of bicalutamide (Casodex) as adjuvant treatment in early prostate cancer (EPC).

METHODS

A Markov state transition model was developed, using disease progression rates from a large (N = 8113) clinical trial program comparing bicalutamide in addition to standard care with standard care alone. Utility scores for different disease stages were obtained from published reports. Costs of disease progression were obtained from a retrospective patient chart analysis in six Belgian centers (n = 60). The time horizon was 15 years and the analysis was conducted from the public payer perspective.

RESULTS

The model showed good validity in predicting clinical outcomes. At a time horizon of 15 years, an incremental cost-effectiveness of 27,059 euros/QALY was obtained. The main factors influencing conclusions included the time horizon, the duration of bicalutamide treatment, which was set at a maximum (5 years) in the base case, and possible differences in prognosis of metastatic cancer between comparators. Also the discounting of health effects significantly altered cost-effectiveness ratios. Many of these influences are inherently associated with any cost-effectiveness analysis related to treatment of early, slowly progressing malignancies because such an analysis requires a sufficient time horizon to include not only the treatment costs but its benefits as well.

CONCLUSION

Based on the current data, bicalutamide appears to be a cost-effective option for adjuvant treatment of EPC.

External beam radiotherapy for clinically node-negative, localized hormone-refractory prostate cancer: impact of pretreatment PSA value on radiotherapeutic outcomes

PURPOSE

To analyze the results of clinically node-negative, localized hormone-refractory prostate cancer treated with external beam radiotherapy (EBRT) and to investigate the potential prognostic factors that influenced the therapeutic outcome.

METHODS AND MATERIALS

Fifty-three patients who had developed localized hormone-refractory prostate cancer were treated with EBRT between 1994 and 2001. According to the 1992 American Joint Committee on Cancer clinical stage, 4 patients had T2 and 49 had T3 at the start of RT, and 14 patients had a Gleason score <7, 14 had a Gleason score of 7, and 23 had a Gleason score of 8-10. All patients were treated with EBRT using the unblocked oblique four-field technique, with a total dose of 69 Gy. The fraction dose was 3 Gy three times weekly. The median follow-up after RT was 35 months (range, 8-96 months) and after androgen ablation was 73 months (range, 42-156 months).

RESULTS

Of 53 patients, 15 patients subsequently developed clinical relapse, including locoregional and/or distant metastases. The site of first relapse was bone metastasis in 10, lymph nodes in 3, and local failure in 2 patients; 3 patients died of prostate cancer during the analysis period. The 3-year and 5-year cause-specific survival rate was 94% and 87%, respectively, and the 3-year and 5-year clinical relapse-free survival rate was 78% and 56%, respectively. The univariate analysis revealed that a short prostate-specific antigen (PSA) doubling time and high PSA value at the start of RT and a high Gleason score were statistically significant factors for the risk of clinical relapse. Multivariate analysis demonstrated that the PSA value (PSA <or=15 vs. >or=15 ng/mL) at the start of RT was an independent prognostic factor.

CONCLUSION

EBRT could be a treatment of choice for clinically node-negative, localized, hormone-refractory prostate cancer.

Prospective Randomized Trial Comparing Flutamide as Adjuvant Treatment versus Observation after Radical Prostatectomy for Locally Advanced, Lymph Node-Negative Prostate Cancer

OBJECTIVE

To assess the efficacy and the tolerability of flutamide as adjuvant treatment after radical prostatectomy for locally advanced, lymph node-negative prostate cancer.

METHODS

Men with locally advanced, lymph node-negative prostate cancer were randomized after radical prostatectomy to receive either flutamide 750mg daily or no adjuvant treatment. Recurrence-free and overall survival were the study end points. Recurrence was defined as a PSA value greater than 5ng/ml or two values greater than 2ng/ml more than three months apart with increasing tendency or three values greater than 1ng/ml more than three months apart with increasing tendency or any clinical recurrence.

RESULTS

309 patients (157 in the control arm and 152 in the flutamide arm) were eligible for efficacy analysis. The median follow-up was 6.1 years. Recurrence-free survival was better in the flutamide group ( P=0.0041), there was, however, no detectable difference in overall survival ( p=0.92 ). Moreover, there was a considerable toxicity reported in the flutamide group.

CONCLUSION

Although having some effect on disease recurrence, adjuvant flutamide treatment does not improve median-term overall survival after radical prostatectomy for locally advanced, lymph node-negative prostate cancer.

Recurrent prostate cancer following external beam radiotherapy

All patients who undergo curative therapy for prostate cancer should be followed for a prolonged period of time to determine tumor control and treatment toxicity for quality assurance purposes. Follow-up duties may be reasonably shared between the oncologist and the family doctor or urologist: however, it is probable that some follow-up information specific to the irradiated patient will be lost unless the oncologist maintains regular contact with the patient, especially in the first 5 years of follow-up when late radiation effects are most likely to appear. There is no strong evidence that patients stop being at risk for recurrence at any time after treatment, and because PSA testing is an accurate, simple, and inexpensive method of determining post-RT tumor status, it is recommended that periodic PSA measurements be continued for life. In the absence of a rising PSA, all other tests and visits are unnecessary to determine post-RT tumor control. Because DRE has been shown to be of limited utility in follow-up of irradiated patients, it should be possible to effectively follow patients remotely. This could be done by asking patients to have PSA tests done, forward the results to their physicians, and report treatment toxicity when it occurs. Only abnormal results would trigger an office visit. This strategy is being evaluated in clinical trials. The alternative is to delegate the follow-up to the primary-care physician with guidelines as to when referral back is required. Follow-up frequency, and the most beneficial follow-up investigations vary from scenario to scenario, and are influenced by the likelihood of relapse, time to relapse, and planned intervention. These decisions are influenced in turn by the initial presentation--either with high or low risk factors--and by the patient's general state of health at completion of EBRT. Effective follow-up also requires active patient cooperation that only can be achieved after discussion of the goals of follow-up with the patient and with the patient's full understanding of the process. The follow-up strategy proposed in Fig. 1 is most suitable for a fit patient with low or intermediate risk factors who wishes to consider all salvage options should he relapse, or for the high-risk individual in situations in which the probability of systemic relapse is of major concern. Young patients with very adverse risk factors may benefit from even closer follow-up in the early years after EBRT and the elderly or frail may require only occasional visits to record or treat treatment toxicity and to ensure clinical non-progression.

Adjuvant hormone therapy after radiation or surgery for localized or locally advanced prostate cancer

Prostate cancer is being diagnosed at an earlier age and earlier disease stage than previously and increasing numbers of relatively young men are receiving potentially curative radical prostatectomy or radiotherapy for early prostate cancer. Although many of these men have an excellent outcome, a significant proportion subsequently experience disease recurrence or cancer-related death. Men with unfavorable tumor characteristics at the time of radical prostatectomy or radiotherapy are particularly at high risk of experiencing disease recurrence. One strategy to improve outcome for these men is adjuvant hormone therapy (hormone therapy administered immediately after therapy of primary curative intent). Surgical castration (bilateral orchiectomy), medical castration using the luteinizing hormone-releasing hormone (LHRH) agonist goserelin, and antiandrogen monotherapy have been investigated as adjuvant hormone therapy to radical prostatectomy and radiotherapy, and each therapy has demonstrated clinical benefits because of a significant improvement in disease-free survival. Furthermore, data are available to indicate that adjuvant hormone therapy achieved by goserelin or bilateral orchiectomy improves overall survival, particularly in men at high risk of progression. Because the effects of LHRH agonists are reversible, they provide a more acceptable method of adjuvant therapy compared to bilateral orchiectomy, particularly in the adjuvant setting, and are preferred by patients. However, the adverse effects on quality of life, in particular on sexual interest and function and bone mineral density, may limit the use of LHRH agonists in some patients. However, these parameters are maintained with nonsteroidal antiandrogens. The first data from the Early Prostate Cancer program indicate that adjuvant bicalutamide 150 mg is associated with a significant improvement in progression-free survival after radical prostatectomy or radiotherapy. Gynecomastia and breast pain are the most common side effects associated with bicalutamide therapy. Medical or surgical castration in combination with an antiandrogen (combined androgen blockade) is another option for use as an adjuvant hormone therapy. However, no study has reported on the use of combined androgen blockade in this setting. Adjuvant hormone therapy provides clinicians with another treatment option for patients with early prostate cancer and unfavorable tumor characteristics.

Nuclear hormone receptor targeted virtual screening

Virtual library screening (VLS) is emerging as a valuable drug lead discovery tool. ICM-VLS implementation of this technology was evaluated on a benchmark set of nuclear hormone receptors (NRs), an important therapeutic target family. Over 5000 structurally diverse compounds, including 78 known NR ligands, were screened against 18 crystal structures and one computer model of 10 NR ligand binding domains in their active or inactive states. The results confirm the ability of the VLS method to generate highly focused subsets of the input chemical library, enriched 33- to 100-fold for all but one receptor studied. However, receptor flexibility remains to be fully addressed, and the choice of the specific conformation used for screening may determine the success of the exercise. We observe that for a particular ligand VLS can often identify the correct target within the receptor family, although the technology is unable to reliably discriminate between the closely related receptor isoforms. Additionally, our results suggest that VLS may be applied successfully without an experimental structure of the receptor by using a homology model. These data represent a realistic snapshot of the state-of-the-art of NR-targeted VLS and define the recent progress and the remaining limitations of the technology.

Finasteride and flutamide therapy in patients with advanced prostate cancer: response to subsequent castration and long-term follow-up

OBJECTIVES

To report the efficacy of castration after progression on finasteride and flutamide. Standard androgen deprivation strategies for prostate cancer typically lead to castrate levels of testosterone. One alternative is the use of finasteride and flutamide.

METHODS

A Phase II trial evaluated the combination of finasteride (5 mg/day) and flutamide (250 mg three times daily) in patients with rising prostate-specific antigen levels after local treatment for prostate cancer or with newly discovered metastatic disease. Patients were followed up for subsequent events, including castration-free, androgen-independent prostate cancer (AIPC)-free, and overall survival.

RESULTS

With a median follow-up of 88 months, 5 patients (25%) continued on finasteride and flutamide, and 12 had stopped this combination and subsequently underwent medical or surgical castration. No patients experienced a flutamide withdrawal effect. All patients experienced more than a 50% decline in prostate-specific antigen after castration (mean 89%). The median protocol treatment failure-free survival was 29.9 months, the median castration-free survival was 37 months, and the median AIPC-free survival was 48.6 months. At 5 years, the overall survival rate was 65% (95% confidence interval 47% to 90%); 29% were alive and have not required castration, and 35% were alive and free of AIPC.

CONCLUSIONS

Finasteride and flutamide have a durable effect in suppressing prostate-specific antigen progression in some men with advanced prostate cancer. Furthermore, castration induces secondary responses that may be of shorter duration than if started initially, although the overall period of hormonally responsive prostate cancer is more than 4 years.

The truth is out there: an overall perspective on androgen deprivation

Androgen deprivation therapy (ADT) is a mainstay in the treatment of prostate cancer. The ideal timing, duration and composition of ADT remains undefined. At the present time, first-line therapy consists of orchiectomy, LHRH agonists, or combined androgen blockade (CAB). However, new combinations and treatment settings show promise for improving outcomes and decreasing toxicity.

Anticonvulsant effect of flutamide on seizures induced by pentylenetetrazole: involvement of benzodiazepine receptors

PURPOSE

There is some structural similarity between the androgen receptor antagonist, flutamide (Flut) and benzodiazepines (BZDs). We evaluated the possible anticonvulsant effect and interaction of Flut with BZD receptors in common seizure models.

METHODS

(a) Different groups of mice each were pretreated i.p. with Flut, and after 0.5 h, they received chemoconvulsants [pentylenetetrazole (PTZ), bicuculline, aminophylline, strychnine or kainic acid]. Latency and incidence of a clonic seizure were recorded. (b) Mice were pretreated i.p. with Flut, and after 0.5 h, transauricular electroshock was applied. Occurrence of a tonic seizure was observed. (c) Amygdala-kindled rats were pretreated i.p. with Flut, and 0.5, 1, or 2 h later, they were stimulated at afterdischarge threshold. Then the seizure parameters (afterdischarge duration, seizure severity, and stage 5 duration) were recorded. (d) The effect of Flut on clonic seizure threshold was determined by i.v. infusion of bicuculline or PTZ to different groups of Flut-receiving mice. To determine the possible interaction of Flut with BZD receptors, the flumazenil (FMZ)+Flut effect on clonic seizure threshold was compared with the effect of Flut. (e) Neurotoxicity of Flut was evaluated by rotarod test at 30 min after administration.

RESULTS

Flut produced a dose-dependent anticonvulsant effect against PTZ-induced seizures [median effective dose (ED50), 67.0 mg/kg]. Moreover, Flut elevated the clonic seizure threshold induced by bicuculline or PTZ. FMZ reversed the effect of Flut on the threshold of PTZ seizures. A median toxic dose (TD50) value of 124.8 mg/kg was obtained for Flut.

CONCLUSIONS

Flut both blocks PTZ-induced clonic seizures and elevates the threshold of PTZ or bicuculline-induced clonic seizures, through interaction with BZD receptors.

3 beta-acetoxyandrost-1,5-diene-17-ethylene ketal functions as a potent antiandrogen with marginal agonist activity

The majority of available antiandrogens have been reported to possess agonist activity to induce prostate-specific antigen, which might result in antiandrogen withdrawal syndrome. Here we report the identification of 3 beta-acetoxyandrost-1,5-diene-17-ethylene ketal (ADEK) from dehydroepiandrosterone metabolites and derivatives as a potent antiandrogen. We found ADEK could interrupt androgen binding to the androgen receptor (AR) and suppress androgen-induced transactivations of WT AR and a mutant AR in prostate cancer cells. ADEK inhibited prostate-specific antigen expression as well as growth in LNCaP prostate cancer cells stimulated by androgen. Importantly, ADEK had only marginal agonist effects, as compared with commonly used antiandrogens such as hydroxyflutamide and bicalutamide, leading to a lower possibility of inducing withdrawal response. Moreover, ADEK could block an adrenal androgen androstenediol-induced AR transactivation that hydroxyflutamide and bicalutamide failed to block. These unique antiandrogenic activities make ADEK a potential therapeutic compound that might be able to inhibit AR-mediated prostate cancer progression. Further in vivo studies might facilitate the development of a better antiandrogen for the treatment of prostate cancer.

Neoadjuvant flutamide monotherapy for locally confined prostate cancer

BACKGROUND

We compared the clinical effects and impact on quality of life (QOL) of patients who received a 3-month course of flutamide monotherapy before radical prostatectomy with those who received a 3-month course of luteinizing hormone-releasing hormone (LHRH) agonist monotherapy.

METHODS

Thirty-seven patients with non-metastatic prostate cancer were enrolled in this study (19, flutamide; 18, LHRH agonist). The rates of change of serum prostate-specific antigen (PSA) and testosterone levels, downsizing of prostate volume, the rate of organ confined disease, adverse effects and perioperative scores measured using the European Organization for Research and Treatment of Cancer Prostate Cancer Quality of Life Questionnaire (EORTC-P) and the Sapporo Medical University Sexual Function Questionnaire (SMUF) were analyzed.

RESULTS

At radical prostatectomy, pathological variables were not significantly different in the two groups. Serum testosterone level was significantly higher (mean 359.2 compared to 10.5, P < 0.001), complete response rate of PSA (13% compared to 57%, P = 0.028) and rate of downsizing of prostate volume (mean, -17.7% compared to -35.4%, P = 0.038) were significantly lower in the flutamide group than in the LHRH group. After neoadjuvant hormone therapy, the scores on the sexual problem domain of EORTC-P (P = 0.033) and sexual desire score of SMUF (P = 0.021) were significantly higher in the flutamide group than in the LHRH group. At a median follow-up of 34 months after prostatectomy, biochemical failure-free survival rate in the flutamide group did not differ from that in the LHRH group.

CONCLUSION

This study suggests that flutamide monotherapy can be an acceptable modality as an option for neoadjuvant hormone therapy.

Hormonal therapy: historical perspective to future directions

Prostate cancer is second only to lung and bronchial cancer as the leading cause of cancer death in men. Local treatment, surgery, and radiation remain the mainstay of treatment for early-stage disease. However, in locally advanced and advanced disease, there has been considerable evolution in the hormonal therapies. Suppression of testosterone production, the primary goal of hormonal therapy, may be accomplished with the use of estrogens, antiandrogens, and agonists and antagonists of luteinizing hormone-releasing hormone (LHRH). This article provides an overview of the primary hormonal therapies currently used in prostate cancer. Estrogen therapy was initially the predominant medical form of hormone manipulation and an alternative to orchiectomy. However, serious thrombogenic side effects were associated with its use, which decreased after the introduction of LHRH agonists in the 1980s. Many of the side effects occurring with oral estrogen therapy may be modulated by parenteral administration, and thus estrogen use is being revisited. LHRH agonists effectively reduce testosterone levels to castration levels (<50 ng/mL) within 2 to 4 weeks, although their use is associated with tumor flare. Antiandrogen monotherapy may offer quality-of-life benefits over treatment with androgen deprivation. The additive benefit of combined androgen blockade is yet to be determined. Recent evidence suggests that hormonal therapy may offer a survival benefit when initiated in earlier stages of prostate cancer. Future investigations will be directed to determining the most efficacious regimens.

Side effects of androgen deprivation therapy: monitoring and minimizing toxicity

The current trends in favor of androgen deprivation therapy (ADT) for nonmetastatic prostate cancer at the stage of biochemical recurrence or increasing prostate-specific antigen (PSA) raises the issue of exposing otherwise asymptomatic patients to potential side effects over the longer term. Some of these side effects can have deleterious effects on quality of life, and others may contribute to increased risks for serious health concerns associated with aging. Sexual side effects are the most well-recognized adverse effects from ADT and include loss of libido, erectile dysfunction (ED), and hot flashes. Loss of libido is distressing to many men, and they may not pursue treatments for ED. However, for those who do maintain sexual interest, various remedies are available. The incidence of hot flashes, which may not abate over the course of ADT, is close to 80%. Estrogens, progestin megestrol acetate, medroxyprogesterone acetate, venlafaxine, and cyproterone acetate have been shown to alleviate hot flashes and associated symptoms. Physiologic effects, including gynecomastia, changes in body composition (weight gain, reduced muscle mass, increase in body fat), and changes in lipids, are less commonly recognized as side effects of ADT. These may lead to an exacerbation of potentially more serious conditions, such as hypertension, diabetes, and coronary artery disease. Loss of bone mineral density, anemia, and hair changes also may occur. Additionally, both the diagnosis of prostate cancer and the hormonal therapy can cause psychological distress. These side effects need more systematic study in clinical trials. Physicians should be aware of far-reaching consequences of ADT and should incorporate strategies for preventing and managing toxicities into routine practice.

Effects of estrogenic and antiandrogenic compounds on the testis structure of the adult guppy (Poecilia reticulata)

Sexually mature male guppies (Poecilia reticulata) were exposed to 17beta-estradiol, 4-tert-octylphenol, bisphenol A, flutamide, p,p'-DDE, or vinclozolin to determine the effects of these estrogenic or antiandrogenic substances on the testis structure. Flutamide, p,p'-DDE, 4-tert-octylphenol, and bisphenol A exposure caused similar effects. These included a reduced number of spermatogenetic cysts and an increased number of spermatozeugmata in the ducts. These effects are indicative of a blocked spermatogonial mitosis. 17beta-Estradiol produced effects different from those of the other compounds studied. The effects were seen as an increased number of hypertrophied Sertoli cells/efferent duct cells. The mammalian antiandrogen vinclozolin had no observable effects on the testis structure when given in doses of 1, 10, or 100 microg/mg food.