Tolerability, efficacy and pharmacokinetics of bicalutamide 300 mg, 450 mg or 600 mg as monotherapy for patients with locally advanced or metastatic prostate cancer, compared with castration

Predictive value of low testosterone concentrations during and prior to enzalutamide treatment in metastatic castration-resistant prostate cancer

BACKGROUND

Enzalutamide is an effective treatment for metastatic castration-resistant prostate cancer (mCRPC) patients. However, variances in responses are observed and there is a need for biomarkers predicting treatment outcome and selection. In this study, we aimed to explore the predictive value of testosterone for first-line enzalutamide treatment of mCRPC.

METHODS

A retrospective analysis of 72 mCRPC patients with no prior abiraterone or docetaxel treatment was performed. Serum testosterone was measured using a liquid chromatography tandem-mass spectrometry method. Association of pre- and during-enzalutimide treatment testosterone levels with progression-free survival (PFS) and failure-free survival (FFS) was investigated using univariate and multivariate Cox models. Testosterone levels were dichotomized into a low (Q1) and high (interquartile range-Q4) group.

RESULTS

Median PFS (7.4 v. 20.8 months, P<0.0001) and FFS (6.6 v. 17.7 months, P<0.0001) were shorter for patients with low testosterone levels (<0.217 nmol/L) during enzalutamide treatment. Furthermore, univariate Cox proportional hazards models revealed that low testosterone levels were associated with shorter PFS (HR 3.5, 95%CI 1.9-6.3; P<0.001) and FFS (HR 3.1, 95%CI 1.7-5.5; P<0.001). Pre-treatment testosterone levels were lower than during-treatment levels (P<0.0001) and low pre-treatment testosterone levels (<0.143 nmol/L) were associated with shorter median PFS (12.6 v. 20.5 months, P<0.01) and FFS (12.6 v. 22.5 months, P<0.01).

CONCLUSION

The results of this study suggest that low serum testosterone levels during and prior to enzalutamide treatment can predict progression in mCRPC patients and identifies tumors resistant to next-in-line enzalutamide treatment. Validation in a prospective cohort is warranted.

Phase II Study of Enzalutamide for Patients With Androgen Receptor-Positive Salivary Gland Cancers (Alliance A091404)

PURPOSE

The androgen receptor (AR) is expressed (+) in a subset of salivary gland cancers (SGCs). This phase II trial evaluated the efficacy of the antiandrogen enzalutamide in AR+ SGC.

METHODS

Patients with locally advanced/unresectable or metastatic AR+ SGCs were enrolled. Enzalutamide (160 mg) was given orally once daily. The primary end point was the best overall response rate per RECIST v1.1 within eight cycles. Confirmed responses in ≥ 5 of 41 patients would be considered promising. Secondary end points were progression-free survival, overall survival, and safety.

RESULTS

Forty-six patients were enrolled; 30 (65.2%) received prior systemic therapy, including 13 (28.3%) with AR-targeted drugs. Of seven (15.2%) partial responses (PRs), only two (4.3%) were confirmed per protocol and counted toward the primary end point. Twenty-four patients (52.2%) had stable disease; 15 (32.6%) had progression of disease as best response. Twenty-six patients (56.5%) experienced tumor regression in target lesions; 18 (39.1%) had partial response/stable disease ≥ 6 months. Tumor regressions were observed in female patients (5 of 6 [83.3%]) and those who received prior AR- (6 of 13 [46.2%]) or human epidermal growth factor receptor 2-targeted therapies (5 of 8 [62.5%]). Three patients remained on treatment at data cutoff (duration, 32.2-49.8 months). The median progression-free survival was 5.6 months (95% CI, 3.7 to 7.5); the median overall survival was 17.0 months (95% CI, 11.8 to 30.0). The most common adverse events were fatigue, hypertension, hot flashes, and weight loss. Total and free testosterone levels increased by a mean of 61.2% and 48.8%, respectively, after enzalutamide.

CONCLUSION

Enzalutamide demonstrated limited activity in AR+ SGC, failing to meet protocol-defined success in part because of a lack of response durability. Strategies to enhance the efficacy of antiandrogen therapy are needed.

Testosterone analysis in prostate cancer patients

Testosterone is an essential steroid hormone associated with a wide variety of biological processes in humans. In prostate cancer, androgen signaling is an important driver of tumor cell growth. Depletion of gonadal testosterone, achieved by surgical or chemical castration, prevents androgenic signaling and temporally reduces, stops or reverses tumor growth before inevitable progression to castration-resistant prostate cancer occurs. Additional treatment strategies targeting androgenic signaling have become available, although these are without curative intent. While circulating testosterone is also associated with disease risk and potential clinical utility, the main use in the clinical lab is monitoring adequate castration and subsequent resistance to therapy. Adequate castrate testosterone concentrations are currently based on over 50 year-old double-isotope derivative assays that are disputed in automated immunoassay (IA) analysis. The debate has been further fueled with the introduction of mass spectrometry-based assays for testosterone, offering a substantial increase in sensitivity and specificity. In this review, we discuss testosterone regulation and androgen deprivation therapy in prostate cancer. We provide an overview of the developments in testosterone analysis for monitoring adequate castration and resistance to therapy. Current clinical practice and future clinical utility will be discussed. Finally, clinical and research recommendations will be presented.

Nonrandomized Comparison of Efficacy and Side Effects of Bicalutamide Compared With Luteinizing Hormone-Releasing Hormone (LHRH) Analogs in Combination With Radiation Therapy in the CHHiP Trial

PURPOSE

CHHiP is a randomized trial evaluating moderately hypofractionated radiation therapy for treatment of localized prostate cancer. Of all participants, 97% of them had concurrent short-course hormone therapy (HT), either luteinizing hormone-releasing hormone analog (LHRHa) or 150 mg of bicalutamide daily. This exploratory analysis compares efficacy and side effects in a nonrandomized comparison.

METHODS AND MATERIALS

In our study, 2700 patients received LHRHa and 403 received bicalutamide. The primary endpoint was biochemical/clinical failure. Groups were compared with Cox regression adjusted for various prognostic factors and stratified by radiation therapy dose. A key secondary endpoint was erectile dysfunction (ED) assessed by clinicians (using scores from Late Effects on Normal Tissues: Subjective/Objective/Management [LENT-SOM] subjective erectile function for vaginal penetration) and patients (single items within the University of California-Los Angeles Prostate Cancer Index [UCLA PCI] and Expanded Prostate Cancer Index Composite [EPIC]-50 questionnaires) at 2 years and compared between HT regimens by χ2 trend test.

RESULTS

Bicalutamide patients were significantly younger (median 67 vs 69 years LHRHa). Median follow-up was 9.3 years. There was no difference in biochemical or clinical failure with an adjusted hazard ratio or 0.97 (95% confidence interval, 0.77-1.23; P = .8). At 2 years, grade ≥2 LENT-SOM ED was reported in significantly more LHRHa patients (313 out of 590; 53%) versus bicalutamide (17 out of 68; 25%) (P < .0001). There were no differences in ED seen with UCLA-PCI and EPIC-50 questionnaires.

CONCLUSIONS

In this nonrandomized comparison, there was no evidence of a difference in efficacy according to type of HT received. Bicalutamide preserved clinician assessed (LENT-SOM) erectile function at 2 years but patient-reported outcomes were similar between groups.

Down regulation of U2AF1 promotes ARV7 splicing and prostate cancer progression

The present study aims to investigate the roles of U2 Small Nuclear RNA Auxiliary Factor 1 (U2AF1) in the resistance to anti-androgen treatment in prostate cancer and its underlying mechanism. U2AF1 and androgen receptor variant 7 (ARV7) knockdown and overexpression were introduced in PC3 and DU145 cells. In addition, a bicalutamide-resistant PC3 (PC3 BR) cell line was also constructed. Cell count, MTT and soft agar colony formation assays were performed to evaluate cell proliferation. qRT-PCR was applied to determine the mRNA levels of U2AF1, ARV7 and Mitogen-Activated Protein Kinase 1 (MAPK1). Western blot was used to determine the MAPK1 protein expression. A negative correlation between ARV7 and U2AF1 in prostate tumor tissues was observed. U2AF1 downregulation was correlated with poor prognosis in prostate cancer patients. U2AF1 exhibited a negative correlation with ARV7 and its downregulation promoted prostate cancer cell proliferation and bicalutamide resistance. The regulatory effects of U2AF1 on ARV7 splicing were associated with MAPK1. U2AF1 affected prostate cancer proliferation and anti-androgen resistance by regulating ARV7 splicing.

Serial [18F]-FDHT-PET to predict bicalutamide efficacy in patients with androgen receptor positive metastatic breast cancer

BACKGROUND

The androgen receptor (AR) is a potential target in metastatic breast cancer (MBC), and 16β-[¹⁸F]-fluoro-5α-dihydrotestosterone positron emission tomography ([¹⁸F]-FDHT-PET) can be used for noninvasive visualisation of AR. [¹⁸F]-FDHT uptake reduction during AR-targeting therapy reflects AR occupancy and might be predictive for treatment response. We assessed the feasibility of [¹⁸F]-FDHT-PET to detect changes in AR availability during bicalutamide treatment and correlated these changes with treatment response.

PATIENTS AND METHODS

Patients with AR + MBC, regardless of oestrogen receptor status, received an [¹⁸F]-FDHT-PET at baseline and after 4-6 weeks bicalutamide treatment. Baseline [¹⁸F]-FDHT uptake was expressed as maximum standardised uptake value. Percentage change in tracer uptake, corrected for background activity (SUV_cor), between baseline and follow-up PET scan (% reduction), was assessed per-patient and lesion. Clinical benefit was determined in accordance with Response Evaluation Criteria in Solid Tumours (RECIST) 1.1 or clinical evaluation (absence of disease progression for ≥24 weeks).

RESULTS

Baseline [¹⁸F]-FDHT-PET in 21 patients detected 341 of 515 lesions found with standard imaging and 21 new lesions. Follow-up [¹⁸F]-FDHT-PET was evaluable in 17 patients with 349 lesions, showing a decrease in median SUV_cor from 1.3 to 0.7 per-patient and lesion (P < 0.001). Median % reduction per-patient was -45% and per-lesion -39%. In patients with progressive disease (n = 11), median % reduction was -30% versus -53% for patients who showed clinical benefit (in accordance with RECIST (n = 3) or clinical evaluation (n = 3); P = 0.338).

CONCLUSION

In this feasibility study, a bicalutamide-induced reduction in [¹⁸F]-FDHT uptake could be detected by follow-up [¹⁸F]-FDHT-PET in patients with AR + MBC. However, this change could not predict bicalutamide response.

CLINICAL TRIAL INFORMATION

NCT02697032.

Androgen Deprivation Therapy for Prostate Cancer

In the contemporary scene, less than 5% of men with newly diagnosed prostate cancer (PC) have metastases at first presentation, compared to 20-25%, more than 20 years ago. Nonetheless, the use of androgen deprivation therapy (ADT) has increased over the years, suggesting that patients in Europe and United States may receive ADT in cases of lower disease burden, and not always according to evidence based indications. Nonetheless, PC remains the second most common cause of cancer death after lung cancer in American men. Thus, there is a need for more effective, specific and well tolerated agents which can provide a longer and good quality of life while avoiding the side effects related to disease and treatment morbidity.After mentioning the current knowledge on the endocrinology of androgens and androgen receptor, relevant to PC development, as well as the possible events occurring during PC initiation, we will compare different hormonal compounds available for the treatment of PC, both from a pharmacological standpoint, and in terms of contemporary clinical indications.

Co-targeting AR and HSP90 suppresses prostate cancer cell growth and prevents resistance mechanisms

Persistent androgen receptor (AR) signaling in castration resistant prostate cancer (CRPC) underpins the urgent need for therapeutic strategies that better target this pathway. Combining classes of agents that target different components of AR signaling has the potential to delay resistance and improve patient outcomes. Many oncoproteins, including the AR, rely on the molecular chaperone heat shock protein 90 (Hsp90) for functional maturation and stability. In this study, enhanced anti-proliferative activity of the Hsp90 inhibitors 17-allylamino-demethoxygeldanamycin (17-AAG) and AUY922 in androgen-sensitive and CRPC cells was achieved when the agents were used in combination with AR antagonists bicalutamide or enzalutamide. Moreover, significant caspase-dependent cell death was achieved using sub-optimal agent doses that individually have no effect. Expression profiling demonstrated regulation of a broadened set of AR target genes with combined 17-AAG and bicalutamide compared with the respective single agent treatments. This enhanced inhibition of AR signaling was accompanied by impaired chromatin binding and nuclear localization of the AR. Importantly, expression of the AR variant AR-V7 that is implicated in resistance to AR antagonists was not induced by combination treatment. Likewise, the heat shock response that is typically elicited with therapeutic doses of Hsp90 inhibitors, and is a potential mediator of resistance to these agents, was significantly reduced by combination treatment. In summary, the co-targeting strategy in this study more effectively inhibits AR signaling than targeting AR or HSP90 alone and prevents induction of key resistance mechanisms in prostate cancer cells. These findings merit further evaluation of this therapeutic strategy to prevent CRPC growth.

Long Term Progression-Free Survival in a Patient with Locally Advanced Prostate Cancer under Low Dose Intermittent Androgen Deprivation Therapy with Bicalutamide Only

Androgen deprivation is a common treatment option in patients with locally advanced or metastatic prostate cancer. No case of long term treatment with an intermittent approach with only low dose bicalutamide (50 mg daily) has been described yet. We report a 60-year-old patient, initially presenting with a PSA elevation of 19.2 ng/mL in 1996. After diagnosis of well to moderately differentiated prostate cancer by transrectal biopsy, the patient underwent an open radical prostatectomy. Final diagnosis was adenocarcinoma of the prostate, classified as pT3a, pR1, pV0, and pL1. Adjuvant intermittent androgen deprivation therapy with flutamide 250 mg was applied, which was changed to bicalutamide 50 mg once daily when it became available in 2001. Six on-phases were performed and PSA values never exceeded 20 ng/mL. The patient did not experience any serious side effects. To date, there are no clinical or radiological signs of progression. Current PSA value is 3.5 ng/mL.

Long-term Efficacy and Safety of Enzalutamide Monotherapy in Hormone-naïve Prostate Cancer: 1- and 2-Year Open-label Follow-up Results

BACKGROUND

Enzalutamide is an androgen receptor inhibitor with a demonstrated overall survival benefit in metastatic castration-resistant prostate cancer. A phase 2 study of enzalutamide monotherapy in patients with hormone-naïve prostate cancer (HNPC) showed a high response rate for the prespecified primary endpoint (ie, prostate-specific antigen [PSA] response at week 25), regardless of metastases at baseline, and favorable tolerability.

OBJECTIVE

To determine the long-term efficacy and safety of enzalutamide monotherapy at 1 and 2 yr.

DESIGN, SETTING, AND PARTICIPANTS

Open-label, single-arm study in patients with HNPC and noncastrate testosterone (≥230 ng/dl).

INTERVENTION

Oral enzalutamide 160mg/d until disease progression or unacceptable toxicity.

OUTCOME MEASUREMENTS AND ANALYSIS

PSA response (≥80% decline from baseline) assessed at 1 yr (49 wk) and 2 yr (97 wk).

RESULTS AND LIMITATIONS

The median (range) age was 73 (48-86) yr and 26 patients (39%) presented with metastases at study entry. Of 67 patients enrolled, 45 (67%) remained on enzalutamide at week 97. For patients remaining on therapy, the PSA response rate at week 97 was 100% (95% confidence interval 92-100%). Of 26 patients with metastases at baseline, 13 (50%) had a complete and four (15.4%) had a partial response as best overall tumor response up to 97 wk on treatment. There was overall maintenance of total-body bone mineral density (BMD) and moderate changes in lean and fat body mass at 49 and 97 wk. The most common adverse events were gynecomastia, nipple pain, fatigue, and hot flushes. The study limitations include lack of a control group and of endocrine, glycemic, and lipid data at 97 wk.

CONCLUSIONS

Long-term enzalutamide monotherapy in men with noncastrate HNPC is associated with large sustained reductions in PSA, signals indicating a favorable tumor response, and favorable safety/tolerability profile, with relatively small negative effects on total-body BMD.

PATIENT SUMMARY

In this long-term follow-up of the efficacy and safety of enzalutamide monotherapy in patients with hormone-naïve prostate cancer, enzalutamide maintained long-term reductions in prostate-specific antigen, with a minimal impact on total-body bone mineral density.

TRIAL REGISTRATION

NCT01302041.

Safety of antiandrogen therapy for treating prostate cancer

INTRODUCTION

Antiandrogens are a treatment option in patients with prostate cancer, given either in combination with androgen deprivation or, in selected cases, as monotherapy. New-generation antiandrogens have been recently introduced in clinical practice (enzalutamide) or are under evaluation in clinical trials (ARN-509).

AREAS COVERED

This review elucidates the safety profile of antiandrogens, in particular focusing on the tolerability profile of each drug either when employed in combination with castration or as monotherapy, in hormone-naive or in castration-resistant patients.

EXPERT OPINION

Non-steroidal antiandrogens are widely used in the management of hormone-sensitive disease in combination with luteinizing hormone-releasing hormone agonists or in patients failing front-line treatment with androgen-deprivative maneuvers. In selected patients, non-steroidal antiandrogen monotherapy appears to yield comparable results as castration. Novel non-steroidal antiandrogens have been investigated with promising results in castration-resistant prostate cancer. Beyond the safety profile specific to any individual compound, increased testosterone and 17β-estradiol levels are commonly observed during antiandrogen monotherapy, leading to gynecomastia and breast pain. The safety profile of old and novel antiandrogens should be taken into account by clinicians in decision making and in selecting the most suitable patients. Beyond patient selection, full clinical evaluation of patient co-morbidities that might affect the drug tolerability and clinical monitoring are anyway required.

Enzalutamide monotherapy in hormone-naive prostate cancer: primary analysis of an open-label, single-arm, phase 2 study

BACKGROUND

The androgen receptor inhibitor enzalutamide is approved for the treatment of metastatic castration-resistant prostate cancer that has progressed on docetaxel. Our aim was to assess the activity and safety of enzalutamide monotherapy in men with hormone-naive prostate cancer.

METHODS

This trial is an ongoing open-label, single-arm, phase 2 study, done across 12 European sites. Men aged over 18 years, with hormone-naive prostate cancer for whom hormone therapy was indicated, and who had non-castration levels of testosterone and prostate-specific antigen (PSA) of 2 ng/mL or greater at screening, and an Eastern Cooperative Oncology Group score of 0, received oral enzalutamide 160 mg/day. The primary outcome was the proportion of patients with an 80% or greater decline in PSA at week 25. All analyses included all patients who had received at least one dose of the study drug. This study is registered with ClinicalTrials.gov, number NCT01302041.

FINDINGS

67 men were enrolled into the study. 62 patients (92.5%, 95% CI 86.2-98.8) had a decline in PSA of 80% or greater at week 25. The most commonly reported treatment-emergent adverse events up to week 25 were gynaecomastia (n=24), fatigue (n=23), nipple pain (n=13), and hot flush (n=12), all of which were of mild to moderate severity. Nine patients had a treatment-emergent adverse event of grade 3 or higher, most of which were reported in one patient each, except for pneumonia (grade 3, two patients) and hypertension (grade 3, four patients). Five patients reported serious adverse events, none of which were deemed to be treatment related.

INTERPRETATION

Our findings suggest that enzalutamide monotherapy in men with hormone-naive prostate cancer of varying severity provides a level of disease suppression, and was generally well tolerated. These findings provide a rationale for further investigation of clinical response and outcomes with enzalutamide in non-castrate men with prostate cancer.

Contemporary role of androgen deprivation therapy for prostate cancer

CONTEXT

Androgen deprivation therapy (ADT) for prostate cancer (PCa) represents one of the most effective systemic palliative treatments known for solid tumors. Although clinical trials have assessed the role of ADT in patients with metastatic and advanced locoregional disease, the risk-benefit ratio, especially in earlier stages, remains poorly defined. Given the mounting evidence for potentially life-threatening adverse effects with short- and long-term ADT, it is important to redefine the role of ADT for this disease.

OBJECTIVE

Review the published experience with currently available ADT approaches in various contemporary clinical settings of PCa and reported serious treatment-related adverse events. This review addresses the level of evidence associated with the use of ADT in PCa, focusing upon survival outcome measures. Furthermore, this paper discusses evolving approaches targeting androgen receptor signaling pathways and emerging evidence from clinical trials with newer compounds.

EVIDENCE ACQUISITION

A comprehensive review of the literature was performed, focusing on data from the last 10 yr (January 2000 to July 2011) and using the terms androgen deprivation, hormone treatment, prostate cancer and adverse effects. Abstracts from trials reported at international conferences held in 2010 and 2011 were also evaluated.

EVIDENCE SYNTHESIS

Data from randomized controlled trials and population-based studies were analyzed in different clinical paradigms. Specifically, the role of ADT was evaluated in patients with nonmetastatic disease as the primary and sole treatment, in combination with radiation therapy (RT) or after surgery, and in patients with metastatic disease. The data suggest that in men with nonmetastatic disease, the use of primary ADT as monotherapy has not shown a benefit and is not recommended, while ADT combined with conventional-dose RT (<72Gy) for patients with high-risk disease may delay progression and prolong survival. The postoperative use of ADT remains poorly evaluated in prospective studies. Likewise, there are no trials evaluating the role of ADT in patients with biochemical relapses after surgery or RT. In patients with metastatic disease, there is a clear benefit in terms of quality of life, reduction of disease-associated morbidity, and possibly survival. Treatment with bilateral orchiectomy, luteinizing hormone-releasing hormone agonist therapy, with and without antiandrogens has been associated with various serious adverse events, including cardiovascular disease, diabetes, and skeletal complications that may also affect mortality.

CONCLUSIONS

Although ADT is an effective treatment of PCa, consistent long-term benefits in terms of quality and quantity of life are predominantly evident in patients with advanced/metastatic disease or when ADT is used in combination with RT (<72Gy) in patients with high-risk tumors. Implementation of ADT should be evidence based, with special consideration to adverse events and the risk-benefit ratio.

Drug safety is a barrier to the discovery and development of new androgen receptor antagonists

BACKGROUND

Androgen receptor (AR) antagonists are part of the standard of care for prostate cancer. Despite the almost inevitable development of resistance in prostate tumors to AR antagonists, no new AR antagonists have been approved for over a decade. Treatment failure is due in part to mutations that increase activity of AR in response to lower ligand concentrations as well as to mutations that result in AR response to a broader range of ligands. The failure to discover new AR antagonists has occurred in the face of continued research; to enable progress, a clear understanding of the reasons for failure is required.

METHODS

Non-clinical drug safety studies and safety pharmacology assays were performed on previously approved AR antagonists (bicalutamide, flutamide, nilutamide), next generation antagonists in clinical testing (MDV3100, BMS-641988), and a pre-clinical drug candidate (BMS-501949). In addition, non-clinical studies with AR mutant mice, and EEG recordings in rats were performed. Non-clinical findings are compared to disclosures of clinical trial results.

RESULTS

As a drug class, AR antagonists cause seizure in animals by an off-target mechanism and are found in vitro to inhibit GABA-A currents. Clinical trials of candidate next generation AR antagonists identify seizure as a clinical safety risk.

CONCLUSIONS

Non-clinical drug safety profiles of the AR antagonist drug class create a significant barrier to the identification of next generation AR antagonists. GABA-A inhibition is a common off-target activity of approved and next generation AR antagonists potentially explaining some side effects and safety hazards of this class of drugs.

[Analysis of complications in metastatic prostate cancer patients submitted to bilateral orchiectomy]

OBJECTIVE

To analyze the possible complications that the surgical hormonal ablation can cause to the submitted patients.

METHODS

That's an analytical transversal study with a sample of 25 patients, between 58 to 82 years, carriers of metastatic prostate cancer, submitted to the bilateral orchiectomy in the Professor Alberto Antunes University Hospital 's (HUPAA-UFAL), in the period of January of 2003 to December of 2008. It was made an evaluation by an objective questionnaire for those who were still alive.

RESULTS

Of the 25 evaluated patients, 56% were still alive, with average of current age of 71 years, having presented as more frequent complications: reduction of the libido and sexual impotence (100%), bone fragility (64%), problems of memory and variations of mood (57%), hot waves and gain of weight (50%). 86% of the interviewed ones had related to be satisfied with the results of the procedure and had affirmed that they can have a normal daily life, with significant improvement of the clinical stage. About the adjuvant treatments, only 36% had carried through, being most common, chemotherapy (36%) and x-ray (29%).

CONCLUSION

The bilateral orchiectomy constitutes in a good alternative for metastatic prostate cancer patients, in a way that it is observed satisfaction of the majority of the patients in relation to the improvement of the symptoms and the presented complications had not great impact in the daily life of the same ones.

Bicalutamide plus anastrozole for the treatment of gonadotropin-independent precocious puberty in boys with testotoxicosis: a phase II, open-label pilot study (BATT)

OBJECTIVE

To evaluate the efficacy, tolerability, and pharmacokinetics of bicalutamide plus anastrozole in young males with testotoxicosis.

METHODS

This was a multicenter, open-label, single-arm, 12-month, Phase II pilot trial in 14 males (2-9 years) with testotoxicosis treated with bicalutamide (12.5, 25, 50, or 100 mg) and anastrozole (0.5 or 1 mg) daily. The primary outcome was change in growth rate.

RESULTS

At 1 year, the mean (standard deviation) change from baseline in growth rate was -1.6 (+/- 5.1) cm/year and -0.1 (+/- 1.8) SD units, and in bone maturation was -2.3 (+/- 0.5) years. The bone age/chronological age ratio was reduced from 2.1 (+/- 0.6) at baseline to 1.0 (+/- 0.4) (p = 0.00013). Steady-state trough R-bicalutamide and anastrozole concentrations were attained by Day 21 and 8, respectively. Gynecomastia (42.9%) and breast tenderness (12.5%) were the most common treatment-related adverse events.

CONCLUSIONS

Treatment of testotoxicosis with bicalutamide plus anastrozole resulted in slower growth rate.

Androgen deprivation therapy for the treatment of prostate cancer: consider both benefits and risks

CONTEXT

Androgen deprivation therapy (ADT) is increasingly used for the treatment of prostate cancer (PCa), even in clinical settings in which there is no evidence-based proof of prolonged overall survival (OS). ADT, however, may be associated with numerous side effects, including an increased therapy-related cardiovascular mortality.

OBJECTIVE

To discuss different clinical settings in which ADT is currently used and to critically weigh the benefits of ADT against its possible side effects.

EVIDENCE ACQUISITION

A MEDLINE search was conducted to identify original articles and review articles addressing the efficacy and side effects of ADT for the treatment of PCa. Keywords consisted of prostate cancer, hormonal therapy, adverse effects, radical prostatectomy, and radiotherapy. The articles with the highest level of evidence for the various examined end points were identified with the consensus of all authors and were reviewed.

EVIDENCE SYNTHESIS

Even short-term use of ADT may lead to numerous side effects, such as osteoporosis, obesity, sarcopenia, lipid alterations, insulin resistance, and increased risk for diabetes and cardiovascular morbidity. Despite these side effects, ADT is commonly used in various clinical settings in which a clear effect on improved OS has not been shown.

CONCLUSIONS

ADT is associated with an increased risk of multiple side effects that may reduce quality of life and/or OS. Consequently, these issues should be discussed in detail with patients and their families before initiation of ADT. ADT should be used with knowledge of its potential long-term side effects and with possible lifestyle interventions, especially in settings with the highest risk-benefit ratio, to alleviate comorbidities.

Indirect androgen doping by oestrogen blockade in sports

Androgens can increase muscular mass and strength and remain the most frequently abused and widely available drugs used in sports doping. Banning the administration of natural or synthetic androgens has led to a variety of strategies to circumvent the ban of the most effective ergogenic agents for power sports. Among these, a variety of indirect androgen doping strategies aiming to produce a sustained rise in endogenous testosterone have been utilized. These include oestrogen blockade by drugs that act as oestrogen receptor antagonists (antioestrogen) or aromatase inhibitors. The physiological and pharmacological basis for the effects of oestrogen blockade in men, but not women, are reviewed.

Combined androgen blockade in advanced prostate cancer: looking back to move forward

In 1989, Crawford and colleagues suggested that combined androgen blockade with castration plus antiandrogen therapy provided significantly improved survival compared with castration alone. Since then, some studies have supported these results, whereas others have not. To resolve this discrepancy, the Prostate Cancer Trialists' Collaborative Group conducted a metaanalysis of 27 randomized trials to evaluate whether combined androgen blockade has benefits compared with castration alone. The results published in 2000 showed that combined androgen blockade using a nonsteroidal antiandrogen treatment (nilutamide or flutamide) improved survival compared with castration alone, whereas combined androgen blockade using a steroidal antiandrogen agent (cyproterone acetate) reduced survival compared with castration alone. In 2004, an analysis was carried out to evaluate the nonsteroidal antiandrogen agent bicalutamide in the combined androgen blockade setting, by incorporating the data from a trial of combined androgen blockade with bicalutamide versus combined androgen blockade with flutamide with the Prostate Cancer Trialists' Collaborative Group metaanalysis data for combined androgen blockade with flutamide versus castration. This analysis showed that combined androgen blockade with bicalutamide was associated with a 20% reduction in the risk of death compared with castration alone. The survival benefit associated with combined androgen blockade using a nonsteroidal antiandrogen agent should be weighed against the potential for increased toxicity and expense compared with castration alone. Studies have shown that bicalutamide has a better tolerability profile than flutamide or nilutamide. Furthermore, cost-benefit analyses of combined androgen blockade with bicalutamide suggest it is a cost-effective option versus castration alone and versus combined androgen blockade with flutamide. In summary, the present evidence suggests that combined androgen blockade with a nonsteroidal antiandrogen agent should be a first-line therapy option in patients with advanced disease.

Survival in men with nonmetastatic prostate cancer treated with hormone therapy: a quantitative systematic review

PURPOSE

We aimed to describe disease-free survival (DFS) and overall survival (OS) in men with localized or locally advanced prostate cancer receiving immediate hormone therapy as adjunct to radiation therapy, adjunct to radical prostatectomy, or stand-alone therapy.

MATERIALS AND METHODS

A systematic literature search of MEDLINE, EMBASE, CancerLit, the Cochrane Library, and Current Contents (from 1986 to September 2006) yielded 35 high-quality clinical trials (n = 11,105 patients) which formed the evidence base. Selected studies were required to address early hormone therapy in nonmetastatic prostate cancer only. Data on DFS and OS were extracted from individual trials, summarized statistically, and displayed in graphic form.

RESULTS

Survival probabilities were extracted from 16 trials (n = 5,987 patients) addressing hormone therapy as an adjunct to radiation therapy, 11 trials (n = 1,885 patients) investigating hormone therapy as an adjunct to prostatectomy, and 10 trials (n = 3,233 patients) evaluating hormone therapy alone. In men receiving hormones and radiation, estimated 5-year DFS and OS were 52% and 82%, whereas median DFS and OS were 5.4 years and more than 7 years, respectively. In men receiving hormones and surgery, 5-year DFS and OS were 64% and 90%, whereas median DFS and OS were more than 6 years and more than 7 years, respectively. In men receiving hormones alone, 5-year DFS and OS were 57% and 70%, whereas median DFS and OS were 6.0 years and more than 7 years, respectively.

CONCLUSION

This systematic review provides a new baseline for expected DFS and OS in patients treated with hormone therapy for nonmetastatic prostate cancer. Survival in these men may be longer than estimated previously.