Nilutamide as second line hormone therapy for prostate cancer after androgen ablation fails

Advances in the Treatment of Prostate Cancer

Several recent advances have been made in the management of prostate cancer. Active surveillance is an increasingly attractive and reasonable approach for those with low-volume, low-risk disease. For locally advanced or localized high-risk disease, neoadjuvant and adjuvant therapies are emerging as the standard of care. Innovative uses of traditional hormonal treatments can potentially limit common side effects. Recent data also support the utility of second-line hormonal therapy. For the first time, a survival advantage with the use of chemotherapy has been established. Much work is under way to augment its efficacy with novel agents such as targeted therapeutics and tumor vaccines. Recent scientific breakthroughs suggest additional strategies in treating prostate cancer.

Treatment algorithm in hormone-resistant prostate cancer: Practical guidelines

Treatment of hormone-resistant prostate cancer can be a challenging situation. The first important step in treating this condition is to assess if one has achieved the castrate level or not. If the castrate levels are not achieved, attempt should be made to achieve so. If the castrate level is achieved, then androgen withdrawals may be of help. Supportive care, care of the clinical problems forms an integral part of the treatment. Cancer-specific chemotherapy is certainly an option in progressive disease.

The case for secondary hormonal therapies in the chemotherapy age

PURPOSE

Virtually all patients with high risk localized and metastatic prostate cancer who are treated with androgen deprivation therapy eventually have progressive clinical or biochemical disease despite this therapy. Despite this fact numerous therapies are available that target the interaction of androgen and androgen receptor in the castrate testosterone milieu and many clinical investigations are under way in this area.

MATERIALS AND METHODS

This literature review focuses on the current clinical literature in support of secondary hormonal therapy.

RESULTS

Despite low androgen levels the androgen receptor remains active through the amplification, mutation or alteration of coactivator function. These observations suggest that secondary hormonal therapies remain a reasonable clinical approach. Such approaches can be receptor or ligand directed. Receptor directed approaches to secondary hormonal therapy are antiandrogen withdrawal, sequential use of antiandrogens and estrogenic compounds. Ligand directed therapies are adrenal cortex inhibitors, such as ketoconazole and others in clinical development. Furthermore, in the context of androgen independent tumor growth in patients with metastatic disease clinicians are now faced with the choice of using chemotherapy or secondary hormonal manipulations. Appropriate patient selection is a critical component to the effective use of these agents.

CONCLUSIONS

The modest activity of these secondary therapies challenges the notion that advancing prostate cancer uniformly becomes hormone refractory. It offers an alternative to the early use of chemotherapy in patients with androgen independent disease.

Recent progress in hormonal therapy for advanced prostate cancer

PURPOSE OF REVIEW

Primary androgen deprivation therapy and secondary hormonal therapy remain the cornerstones of treatment for advanced prostate cancer. This review outlines the basic evidence for use of hormonal therapy while highlighting major research developments made in the past year.

RECENT FINDINGS

Recent research on androgen deprivation therapy has suggested that patients with high-risk features may have longer metastasis-free survival with early initiation of androgen deprivation therapy. Fracture risk has been shown to be significantly increased in patients on androgen deprivation therapy and is correlated with duration of treatment. In the treatment of androgen-independent prostate cancer, oral premarin has been shown to induce of prostate specific antigen responses more than 50% in 32% of patients, though thromboembolism remains a risk despite prophylactic low-dose warfarin. Transdermal estradiol has been associated with virtually no cardiovascular toxicity, but induced of prostate specific antigen responses more than 50% in only 12.5% of patients. Clinical studies of nilutamide, flutamide, and ketoconazole have further clarified efficacy of these secondary hormonal treatments.

SUMMARY

Optimal timing of androgen deprivation therapy awaits the results of randomized trials, but available evidence indicates that patients with high-risk features may benefit from early androgen deprivation therapy. New estrogen-based therapies have shown promising efficacy in the treatment of androgen-independent prostate cancer, with significantly less cardiovascular toxicity than traditional estrogens.

Secondary Hormonal Manipulations in Prostate Cancer

Targeting AIPC with therapies that affect the mechanisms of androgen receptor signaling despite a castrate testosterone milieu is an active and growing area of clinical research. At present, for patients with AIPC, the data support the maintenance of the castrate state, recognition of the AAWD phenomenon,the sequential use of oral antiandrogens, and a trial of estrogens or adrenal androgen-targeted therapies. Novel agents are being developed that seek to prolong the duration of clinical responses and the overall response rate.

Combined androgen blockade: an update

The use of combined androgen blockade therapy in prostate cancer management remains controversial. This article reviews the effect of the different non-steroid androgens in blocking androgen-independent activation of the androgen receptor in the androgen-depleted environment, and the potential benefit of bicalutamide in comparison to the first generation of anti-androgens (flutamide and nilutamide). An estimate of the benefit of combined therapy with bicalutamide suggests there is a high probability that bicalutamide 50 mg as combined therapy provides a survival advantage over castration alone. This treatment must be balanced against the potential for an increase in side-effects and a consequent adverse effect on the patient's quality of life.

Arylisothiocyanato selective androgen receptor modulators (SARMs) for prostate cancer

A new series of androgen receptor targeted agents (ARTA) was prepared and tested in androgen-dependent and -independent prostate cancer cell lines. These agents were bicalutamide analogs with isothiocyanato substituted B-rings. Also, the linker sulfone of R-bicalutamide was maintained or replaced with several alternative linkages including ether, amine, N-methylamine, thioether, and methylene (in this case the product was a racemic mixture) functional groups at the X-position. To expand the structure-activity relationship (SAR) of these arylisothiocyanato AR ligands, B-ring halogenated arylisothiocyanato ligands were also prepared and tested. The arylisothiocyanato AR ligands showed strong binding affinities to AR ranging from 0.6 to 54 nM. Among them, thioether and ether linkages demonstrated high binding affinities (0.6 and 4.6 nM, respectively) and selective cell growth inhibition (approximately 3- to 6-fold) for LNCaP, an androgen-dependent prostate cancer cell line, when compared to the androgen independent prostate cell lines (DU145, PC-3, and PPC-1) and a bladder cell line (TSU-Pr1). However, the ligands were inactive (IC50>100 mM) in a normal monkey kidney cell line (CV-1) that was used as the control for non-specific toxicity.

Secondary Hormonal Therapy for Advanced Prostate Cancer

PURPOSE

Androgen ablation remains the cornerstone of management for advanced prostate cancer. Therapeutic options in patients with progressive disease following androgen deprivation include antiandrogen withdrawal, secondary hormonal agents and chemotherapy. Multiple secondary hormonal agents have clinical activity and the sequential use of these agents may lead to prolonged periods of clinical response. We provide a state-of-the-art review of the various agents currently used for secondary hormonal manipulation and discusses their role in the systemic treatment of patients with prostate cancer.

MATERIALS AND METHODS

A comprehensive review of the peer reviewed literature was performed on the topic of secondary hormonal therapies, including oral antiandrogens, adrenal androgen inhibitors, corticosteroids, estrogenic compounds, gonadotropin-releasing hormone antagonists and alternative hormonal therapies for advanced prostate cancer.

RESULTS

Secondary hormonal therapies can provide a safe and effective treatment option in patients with AIPC. The use of steroids and adrenolytics, such as ketoconazole and aminoglutethimide, has resulted in symptomatic improvement and a greater than 50% prostate specific antigen decrease in a substantial percent of patients with AIPC. A similar clinical benefit has been demonstrated with estrogen based therapies. Furthermore, these therapies have demonstrated a decrease in metastatic disease burden. Other novel hormonal therapies are currently under investigation and they may also show promise as secondary hormonal therapies. Finally, guidelines from the United States Food and Drug Administration Prostate Cancer Endpoints Workshop were reviewed in the context of developing new agents.

CONCLUSIONS

Secondary hormonal therapy serves as an excellent therapeutic option in patients with AIPC in whom primary hormonal therapy has failed. Practicing urologists should familiarize themselves with these oral medications, their indications and their potential side effects.

Biology of progressive, castration-resistant prostate cancer: directed therapies targeting the androgen-receptor signaling axis

Prostate cancers that are progressing on medical and surgical therapies designed to ablate the action of androgens continue to express androgen receptor (AR) and to depend on signaling through the receptor for growth. A more clinically relevant classification of castration-resistant disease focuses on the mechanisms of receptor activation, which include (1) changes in the level of ligand(s) in tumor tissue; (2) increased levels of the protein due to gene amplification or altered mRNA expression; (3) activating mutations in the receptor that affect structure and function; (4) changes in coregulatory molecules including coactivators and corepressors; and (5) factors that lead to activation of the receptor independent of the level of ligand or receptor allowing kinase cross talk. From an AR perspective, the term "hormone refractory" is inappropriate. On the basis of this schema, we discuss strategies that are focused on the AR either directly or indirectly, as single agents or in combination, that are in clinical development.

Early Versus Delayed Androgen Deprivation for Prostate Cancer: New Fuel for an Old Debate

The purpose of this review is to discuss the recent increase in data supporting the use of androgen ablation early in the clinical course for patients with nonmetastatic prostate cancer. We systematically reviewed recent publications that report on the use of androgen deprivation (AD) in nonmetastatic prostate cancer patients from the 2003 and 2004 procedings of the American Society of Clinical Oncology, the 2003 and 2004 procedings of the American Urological Association as well as published literature from 2003 to 2005. Five recently published mature randomized trials of AD plus local therapy were evaluated plus two large data sets on the use of AD for patients with serologic relapse after local therapy. Four mature randomized studies demonstrate an overall survival benefit to the use of AD in conjunction with definitive local therapy (three with radiation and one with surgery). One retrospective analysis suggests that AD administered early after serologic progression improves overall survival, and one retrospective analysis shows a reduction in metastasis-free survival but has not yet shown an overall survival benefit. For patients with nonmetastatic prostate cancer with high-risk features, as well as those for serologic relapse, the use of AD before the development of metastatic disease is supported by long-term outcomes from a series of clinical trials. Consideration of AD is therefore warranted early in the clinical course of high-risk patients.

Efficacy of nilutamide as secondary hormonal therapy in androgen-independent prostate cancer

OBJECTIVE

To evaluate the activity of nilutamide as secondary hormonal therapy in patients with androgen-independent prostate cancer (AIPC), as treatment options are limited for these patients and secondary hormonal therapy with antiandrogens has advantages, including low toxicity, oral administration and high patient acceptance.

PATIENTS AND METHODS

We retrospectively identified 45 patients with AIPC who were treated with nilutamide as secondary hormonal therapy in two institutions. The decrease in prostate-specific antigen (PSA) levels, side-effects of treatment, and the relationship between baseline characteristics, type and duration of previous therapy and response to nilutamide were assessed. Most patients received oral nilutamide at 150 mg/day.

RESULTS

Eighteen of 45 evaluable patients (40%) had a PSA level decrease of > or = 50%. Responders (PSA decline > or = 50%) had a median (range) time to progression of 4.4 (0.31-44.7) months. There were responses to nilutamide whether used as the second to fifth line of hormonal therapy. There were no differences in response to nilutamide based on clinical stage, type of local therapy, PSA level at diagnosis or initiation of nilutamide, or type of previous antiandrogen therapy. Responders were more likely to have received monotherapy with luteinizing hormone-releasing hormone analogues or orchidectomy as first-line hormonal treatment (P = 0.02). The most common reversible adverse effects were mild to moderate visual adaptation effects, reported in 20% of patients.

CONCLUSIONS

Nilutamide appears to be an effective secondary hormonal therapy in patients with AIPC and is associated with a mild toxicity profile.

A phase II study of nilutamide in men with prostate cancer after the failure of flutamide or bicalutamide therapy

OBJECTIVE

To determine the prostate-specific antigen (PSA) response and time to PSA or radiographic progression in men with prostate cancer refractory to bicalutamide and/or flutamide therapy.

PATIENTS AND METHODS

Men with histologically confirmed prostate cancer not amenable to curative surgery or radiation therapy were eligible for the study if they had radiographic or PSA progression on at least one antiandrogen (not nilutamide) despite continued androgen suppression and standard antiandrogen withdrawal periods. All men received nilutamide 150 mg/day orally for > or = 8 weeks unless there was unacceptable toxicity or disease progression. All men were evaluated for response, safety and toxicity. Baseline PSA levels, chest X-ray, bone scan and abdominopelvic computed tomography studies were obtained; the re-evaluation included PSA levels every 4 weeks and repeated imaging every 8 weeks in those with baseline abnormalities. The chest X-ray was repeated if there were pulmonary symptoms. Nineteen men were consented and 16 were evaluable for response.

RESULTS

The median (range) Gleason score was 7 (6-9) and the median number of previous second-line therapies was 2 (1-4). Bicalutamide therapy had failed in all patients. At baseline, 13 (of 16 men) had radiographically evident disease, nine with diffuse osseous and four with radiographically measurable metastases. There was no grade 3/4 toxicity; the commonest grade 1/2 toxicities were constipation (three), sensory neuropathy (four), fatigue (six), and visual changes (two) involving transiently altered colour vision and sensitivity to light, respectively. Responses included three partial and 13 with progressive disease.

CONCLUSIONS

The study was discontinued after a planned interim analysis because nilutamide had no apparent activity. Although well tolerated, nilutamide offers benefit to few men with prostate cancer in whom bicalutamide has failed.

Clinical outcome of maximum androgen blockade using flutamide as second-line hormonal therapy for hormone-refractory prostate cancer

OBJECTIVES

To investigate the efficacy of maximum androgen blockade (MAB) using flutamide as second-line hormonal therapy for advanced hormone-refractory prostate cancer (HRPC).

PATIENTS AND METHODS

The study included 55 patients with HRPC who were treated with MAB using flutamide (375 mg daily) as second-line hormonal therapy. All patients had previously received bicalutamide combined with either surgical or medical castration as first-line hormonal therapy, which failed. The effect of the second-line therapy was evaluated by serum prostate-specific antigen (PSA) level alone, and the response defined as a decrease of >50% from the baseline PSA at the start of second-line therapy.

RESULTS

On initiating second-line hormonal therapy there was a reduction in the PSA level in 25 of the 55 patients (45%), among whom 12 (22%) were regarded as responders, while the PSA level continued to increase in the remaining 30 (55%). The median (range) duration of the PSA response was 6 (1-13) months. During the observation period there were no severe side-effects from the second-line MAB therapy. Patients without bone metastases or whose disease progressed >1 year after first-line therapy had a significantly higher incidence of PSA response to second-line therapy, despite no significant effect of other factors examined on the PSA response to second-line therapy. Furthermore, the cause-specific survival in responders to second-line therapy was significantly better than that in nonresponders; however, multivariate analysis showed that no factors, including response to second-line therapy, could be used as independent predictors of cause-specific survival.

CONCLUSIONS

MAB using flutamide as second-line hormonal therapy can give a comparatively favourable PSA response with no severe side-effects; therefore, this therapy may be suitable for patients with HRPC after primary MAB using bicalutamide has failed, particularly in those with no bone metastases or whose disease has progressed for >1 year after first-line therapy.

Antiandrogen, vaccine and combination therapy in patients with nonmetastatic hormone refractory prostate cancer

PURPOSE

There is no current standard treatment for patients with prostate cancer who have received hormonal therapy but have an increasing prostate specific antigen (PSA) without radiographic evidence of metastasis. This trial was designed to analyze toxicity, immunogenicity and time to treatment failure using vaccine, antiandrogen therapy or their sequential use.

MATERIALS AND METHODS

A total of 42 patients were randomized to receive vaccine vs antiandrogen therapy with nilutamide. The vaccine consisted of recombinant vaccinia viruses containing the PSA and B7.1 costimulatory genes as prime vaccinations, and avipox-PSA as boosters. After 6 months patients with an increasing PSA and no metastasis may receive a combination of both treatments.

RESULTS

Three patients on nilutamide were removed from study secondary to grade 3 toxicities but no grade 3 toxicities were attributed to vaccine. In the vaccine arm median time to treatment failure was 9.9 months with 13 of 21 decreases in PSA velocity vs 7.6 months with 16 of 21 decreases in PSA velocity in the nilutamide arm (p =0.28). Of the patients in the nilutamide arm 8 had vaccine added at the time of PSA progression. Median time to treatment failure with combined therapy was 5.2 months, with a median duration from study entry of 15.9 months. Of the patients in the vaccine arm 12 had nilutamide added at the time of PSA progression. Median time to treatment failure with combined therapy was 13.9 months and a median of 25.9 months from initiation of therapy.

CONCLUSIONS

Further studies are merited to investigate the role of combining vaccine with antiandrogen therapy or vaccine followed by vaccine plus antiandrogen therapy in this patient population.

Secondary hormonal manipulations in prostate cancer

Virtually all patients treated with androgen deprivation eventually develop progressive clinical or biochemical disease despite this therapy. Despite low levels of androgen, the androgen receptor remains active, making secondary hormonal therapies a reasonable clinical approach. Considerations for such patients include antiandrogen withdrawal, sequential use of antiandrogens, adrenal cortex inhibitors, and estrogenic compounds. Collectively, the modest activity of these therapies challenges the notion that advancing prostate cancer will uniformly become "hormone refractory."

Prolonged Response to Nilutamide in a Patient with Stage D0.5 Prostate Cancer Who Previously Failed Androgen Deprivation Therapy

There is currently no standard therapy for patients with prostate cancer who have progressive rise in PSA levels despite treatment with hormonal ablation and antiandrogen withdrawal (stage D0.5). One potential treatment option is the use of a different androgen receptor antagonist (ARA), such as nilutamide. We report a case of a 66-year-old gentleman with greater than a 46 month sustained response to nilutamide therapy after failing bicalutamide therapy and its subsequent withdrawal. The patient continues to have undetectable PSA levels and an excellent performance status. This case demonstrates the prolonged response to a second-line ARA in patients deemed to have androgen insensitive prostate cancer. Further investigation of the potential role of nilutamide therapy as second-line antiandrogen therapy is warranted as monotherapy and/or in combination with other promising novel approaches including PSA-based vaccines.

Management of patients with hormone refractory prostate cancer

Prostate cancer is the second most common cancer in men in the UK, and the incidence of prostate cancer has increased dramatically over the past two decades. Although most men are diagnosed at early stage, more than 50% develop locally advanced or metastatic disease. Androgen ablation with luteinising hormone-releasing hormone (LHRH) agonists alone, or in combination with anti-androgens, is the standard treatment for men with metastatic prostate cancer. Unfortunately, almost all men develop progressive disease after a variable time period, despite the maximal androgen blockade. The management of hormone refractory prostate cancer (HRPC) is challenging, as there is no uniformly accepted strategy. Various treatment options, including second-line hormone therapy, are discussed. Chemotherapy is being increasingly used and, importantly, docetaxel and estramustine may play an important role in the near future. The role of radiotherapy, strontium-89, bisphosphonates, novel agents and future therapies are also outlined.

An evaluation of bicalutamide in the treatment of prostate cancer

Although prostate cancer is traditionally considered a disease of old age, improved diagnostic techniques have resulted in early diagnosis, and many men are now treated while still physically and sexually active. Current therapies for prostate cancer often include medical or surgical castration, which cause adverse effects on physical and sexual function; therefore, greater attention has been focused on quality of life. The nonsteroidal antiandrogen bicalutamide is an effective agent with a favorable tolerability profile and, in some settings, represents an alternative to castration. Mature survival data reveal that bicalutamide monotherapy provides survival benefits for untreated locally advanced disease that do not differ significantly from those of castration and maintains better physical capacity and sexual interest. Recent data from a prospective randomized trial demonstrate that bicalutamide given as immediate therapy, either alone or as adjuvant to therapy of curative intent, significantly reduces the risk of objective disease progression in patients with localized or locally advanced prostate cancer. Antiandrogens are also used in combination with castration, a treatment known as combined androgen blockade (CAB), for advanced disease. A randomized trial demonstrated that CAB with bicalutamide is associated with similar survival outcome to CAB with flutamide and is better tolerated. Current evidence demonstrates that bicalutamide currently has a favorable risk-benefit ratio in several stages of prostate cancer and that the role of bicalutamide will be further defined by ongoing studies.

Advances in prostate cancer

PURPOSE OF REVIEW

The purpose of this review is to highlight the most important developments in the diagnosis, prevention, and management of prostate cancer reported in the past year that have been published in the medical literature.

RECENT FINDINGS

Recent research has yielded important insights into the effects of lowering the serum prostate-specific antigen threshold for prostate biopsy on the incidence of prostate cancer and suggests that a cutoff value of 2.5 ng/mL would double the rate of diagnosis of the disease in young men. Other developments demonstrate that oral finasteride reduces the incidence of the disease but increases the proportion of high-grade tumors. The incidence of mutations of the androgen receptor gene has been shown to be lower than was previously thought. New randomized data suggest that for patients with high-risk localized prostate cancer treated with radiation, 4 months of androgen deprivation in combination with whole pelvis radiotherapy confers a clinical benefit. The clinical benefits associated with chemotherapy and supportive care therapies such as the bone targeting bisphosphonates continue to be refined.

SUMMARY

The data reported in the past year have widespread implications for all clinicians involved in the management of prostate cancer, ranging from primary care physicians who screen for and diagnose the disease to those who manage localized as well as systemic disease. Several of the year's findings will result in significant changes in the manner in which the disease is treated.

Role of secondary hormonal therapy in the management of recurrent prostate cancer

Androgen ablation remains the cornerstone of the systemic management of prostate cancer. After initial androgen deprivation, clinical outcomes vary considerably. For the patient with progressive disease after androgen deprivation, multiple therapeutic options are available and include antiandrogen withdrawal, chemotherapy, and secondary hormonal agents. Multiple secondary hormonal agents have clinical activity and the sequential use of these agents may lead to prolonged periods of clinical response. In addition to the use of oral antiandrogens, active secondary hormonal therapies include adrenolytic agents such as ketoconazole and aminoglutethimide, corticosteroids and estrogenic compounds. This article reviews the clinical trial data for these various agents and discusses their role in the management of patients with advanced prostate cancer.