A phase II randomized trial of megestrol acetate or dexamethasone in the treatment of hormonally refractory advanced carcinoma of the prostate

Androgen-glucocorticoid interactions in the era of novel prostate cancer therapy

Great strides have been made in the treatment of castration-resistant prostate cancer (CRPC) with the development of new antiandrogens (enzalutamide) and more potent androgen synthesis inhibitors (abiraterone) that have both improved patient outcomes. These new drugs have also helped unravel the complex biology of androgen-androgen receptor driven prostate cancer and brought into prominence various mechanisms triggering the development of drug resistance and tumour cell survival despite use of androgen deprivation therapy (ADT). The complex role of glucocorticoids in the treatment, management and progression of patients with CRPC is integral to these advances. Historically, glucocorticoid treatment has resulted in both subjective and objective responses in patients with advanced-stage prostate cancer. With the use of these new therapeutic agents, however, unexpected glucocorticoid-related mechanisms that can cause iatrogenic stimulation of prostate cancer growth have emerged, which might contribute to drug resistance and disease progression despite optimal ADT. For example, the upregulation of glucocorticoid receptors (GRs) during enzalutamide therapy results in glucocorticoid-GR-mediated regulation of androgen target genes, leading to escape from enzalutamide blockade. Thus, understanding the biological role of glucocorticoids in patients with prostate cancer is of major importance in the era of new and evolving antiandrogen therapies.

Systemic therapy in men with metastatic castration-resistant prostate cancer:American Society of Clinical Oncology and Cancer Care Ontario clinical practice guideline

PURPOSE

To provide treatment recommendations for men with metastatic castration-resistant prostate cancer (CRPC).

METHODS

The American Society of Clinical Oncology and Cancer Care Ontario convened an expert panel to develop evidence-based recommendations informed by a systematic review of the literature.

RESULTS

When added to androgen deprivation, therapies demonstrating improved survival, improved quality of life (QOL), and favorable benefit-harm balance include abiraterone acetate/prednisone, enzalutamide, and radium-223 ((223)Ra; for men with predominantly bone metastases). Improved survival and QOL with moderate toxicity risk are associated with docetaxel/prednisone. For asymptomatic/minimally symptomatic men, improved survival with unclear QOL impact and low toxicity are associated with sipuleucel-T. For men who previously received docetaxel, improved survival, unclear QOL impact, and moderate to high toxicity risk are associated with cabazitaxel/prednisone. Modest QOL benefit (without survival benefit) and high toxicity risk are associated with mitoxantrone/prednisone after docetaxel. No benefit and excess toxicity are observed with bevacizumab, estramustine, and sunitinib.

RECOMMENDATIONS

Continue androgen deprivation (pharmaceutical or surgical) indefinitely. Abiraterone acetate/prednisone, enzalutamide, or (223)Ra should be offered; docetaxel/prednisone should also be offered, accompanied by discussion of toxicity risk. Sipuleucel-T may be offered to asymptomatic/minimally symptomatic men. For men who have experienced progression with docetaxel, cabazitaxel may be offered, accompanied by discussion of toxicity risk. Mitoxantrone may be offered, accompanied by discussion of limited clinical benefit and toxicity risk. Ketoconazole or antiandrogens (eg, bicalutamide, flutamide, nilutamide) may be offered, accompanied by discussion of limited known clinical benefit. Bevacizumab, estramustine, and sunitinib should not be offered. There is insufficient evidence to evaluate optimal sequences or combinations of therapies. Palliative care should be offered to all patients.

Androgen receptor antagonists for prostate cancer therapy

Androgen deprivation is the mainstay therapy for metastatic prostate cancer (PCa). Another way of suppressing androgen receptor (AR) signaling is via AR antagonists or antiandrogens. Despite being frequently prescribed in clinical practice, there is conflicting evidence concerning the role of AR antagonists in the management of PCa. In the castration-resistant settings of PCa, docetaxel has been the only treatment option for decades. With recent evidence that castration-resistant PCa is far from AR-independent, there has been an increasing interest in developing new AR antagonists. This review gives a concise overview of the clinically available antiandrogens and the experimental AR antagonists that tackle androgen action with a different approach.

Safety of megestrol acetate in palliating anorexia-cachexia syndrome in patients with castration-resistant prostate cancer

There are concerns whether megestrol acetate (MA) stimulates the growth of prostate cancer in castration-resistant prostate cancer (CRPC). We evaluated the effect of cumulative doses of MA on the disease-specific survival (DSS) in patients with CRPC who were receiving Docetaxel-based chemotherapy. From July 2003 through June 2009, we identified 109 consecutive patients with CRPC and who had received docetaxel-based chemotherapy. Of these patients, 68 (62.4%) have not received MA, whereas 21 patients (19.3%) and 20 patients (18.3%) had received low dose MA (total ≤ 18,400 mg) and high dose MA (total > 18,400 mg), respectively. We assessed the effect of several variables on DSS. None of the clinicopathological variables differed among the three groups. When comparing DSS using Kaplan-Meier analysis, there was no statistically significant survival differences among the three groups (P = 0.546). Using multivariate Cox proportional analyses with backward elimination, the number of docetaxel cycles was only significant factor predicting DSS (HR: 0.578, 95% CI: 0.318-0.923, P = 0.016). Cumulative doses of MA as adjuvant treatment for patients with CRPC and who are receiving docetaxel-based chemotherapy, did not affect their DSS. Therefore, MA can be safely administered in cachexic patients with CRPC.

Absence of antitumor activity with prednisone in patients with progressive androgen-independent prostate carcinoma

Corticosteroids are reported to have antitumor activity in patients with androgen-independent prostate carcinoma (AIPCa). This trial, a phase II trial of daily oral prednisone 10 mg four times per day for 56 consecutive days, was designed to confirm this finding. From November 1989 to September 1992 16 patients were enrolled in the study. Baseline tumor measurements were taken upon enrollment and re-evaluated at completion of 56 days. If the patient was responding or stable, a maintenance schedule of 5 mg four times per day was resumed until unacceptable toxicity was reached or tumor growth progressed. Antitumor activity was assessed by the decline in the serum level of prostate specific antigen. Entry criteria included strict evidence for progressive AIPCa, tumor growth associated with castrate testosterone level below 50 ng/dl, and adrenal cortical function tests. Patients continued hormone therapy that induced castrate testosterone level. Two patients required early cessation of therapy secondary to symptomatic tumor progression. Of the remaining 14 patients, no responses were seen,. Four (29%) of 16 patients had transient improvement in performance status. No hematologic toxicity was observed. Nonhematologic toxicity was mild and manageable, consisting of fluid retention and metabolic laboratory abnormalities. Suppressive effect of adrenal cortical function was demonstrated in patients, measured by a decrease in serum levels of dehydroepiandrosterone and dehydroepiandrosterone sulfate. Our results show that corticosteroids have no significant antitumor activity in patients with true progressive AIPCa.

Human steroid biosynthesis for the oncologist

In 2005, results from the Arimidex, Tamoxifen Alone or in Combination (ATAC) trial ushered in a new era of endocrine therapy for hormone-responsive malignancies. This study demonstrated that, compared with tamoxifen (a selective estrogen receptor modulator), anastrozole (aromatase inhibitor [AI]) prolonged time to recurrence and disease-free survival for postmenopausal women with breast cancer. The advantage was even greater for those with estrogen receptor-positive (ER) tumors, and anastrozole was better tolerated than tamoxifen. Since then, AIs have become first-line adjuvant therapy for ER breast cancer in postmenopausal women.In late 2010, a trial comparing abiraterone acetate (a 17-hydroxylase/17,20-lyase [CYP17A1] inhibitor) plus prednisone versus prednisone alone in men with castration-resistant prostate cancer (CRPC) previously treated with docetaxel chemotherapy was terminated early because of the survival benefit in the abiraterone acetate arm. This result not only validated a new therapy for CRPC but also, with the antecedent phase I-II abiraterone studies, shattered our understanding of the molecular mechanisms underpinning CRPC development and progression.Aromatase inhibitors and CYP17A1 inhibitors will be widely used by oncologists, yet fellowship programs provide little training in steroid biosynthesis, compared with training in the biology of standard chemotherapies. Consequently, these drugs might be used without an appreciation of their caveats and pitfalls. The purpose of this review was to acquaint practicing oncologists with the fundamental principles and pathways of steroid biosynthesis, to improve their understanding of how and why these drugs work, and to alert these physicians to potential problems related to the drugs' mechanisms of action.

Systematic review of the clinical effect of glucocorticoids on nonhematologic malignancy

BACKGROUND

Glucocorticoids are often used in the treatment of nonhematologic malignancy. This review summarizes the clinical evidence of the effect of glucocorticoid therapy on nonhematologic malignancy.

METHODS

A systematic review of clinical studies of glucocorticoid therapy in patients with nonhematologic malignancy was undertaken. Only studies having endpoints of tumor response or tumor control or survival were included. PubMed, EMBASE, the Cochrane Register/Databases, conference proceedings (ASCO, AACR, ASTRO/ASTR, ESMO, ECCO) and other resources were used. Data was extracted using a standard form. There was quality assessment of each study. There was a narrative synthesis of information, with presentation of results in tables. Where appropriate, meta-analyses were performed using data from published reports and a fixed effect model.

RESULTS

Fifty four randomized controlled trials (RCTs), one meta-analysis, four phase l/ll trials and four case series met the eligibility criteria. Clinical trials of glucocorticoid monotherapy in breast and prostate cancer showed modest response rates. In advanced breast cancer meta-analyses, the addition of glucocorticoids to either chemotherapy or other endocrine therapy resulted in increased response rate, but not increased survival. In GI cancer, there was one RCT each of glucocorticoids vs. supportive care and chemotherapy +/- glucocorticoids; glucocorticoid effect was neutral. The only RCT found of chemotherapy +/- glucocorticoids, in which the glucocorticoid arm did worse, was in lung cancer. In glucocorticoid monotherapy, meta-analysis found that continuous high dose glucocorticoids had a detrimental effect on survival. The only other evidence, for a detrimental effect of glucocorticoid monotherapy, was in one of the two trials in lung cancer.

CONCLUSION

Glucocorticoid monotherapy has some benefit in breast and prostate cancer. In advanced breast cancer, the addition of glucocorticoids to other therapy does not change the long term outcome. In GI cancer, glucocorticoids most likely have a neutral effect. High dose continuous glucocorticoids have a detrimental effect in nonhematologic malignancy. Glucocorticoid therapy might have a deleterious impact in lung cancer.

Chemotherapy for hormone-refractory prostate cancer

BACKGROUND

Prostate cancer mainly affects elderly men, and its incidence has steadily increased over the last decade. The management of this disease is replete with controversy. In men with advanced, metastatic prostate cancer, hormone therapy is almost universally accepted as the initial treatment of choice and produces good responses in most patients. However, many patients will relapse and become resistant to further hormone manipulation; the outlook for these patients is poor. Many have disease extending to the skeleton, which is associated with severe pain. Therapies for these men include chemotherapy, bisphosphonates, palliative radiotherapy, and radioisotopes. Systemic chemotherapy has been evaluated in men with hormone-refractory prostate cancer (HRPC) for many years, with disappointing results. However, more recent studies with newer agents have shown encouraging results. There is therefore a need to explore the value of chemotherapy in this disease.

OBJECTIVES

The present review aims to assess the role of chemotherapy in men with metastatic HRPC. The major outcome was overall survival. Secondary objectives include the effect of chemotherapy on pain relief, prostate-specific antigen (PSA) response, quality of life, and treatment-related toxicity.

SEARCH STRATEGY

Trials were identified by searching electronic databases, such as MEDLINE, and handsearching of relevant journals and conference proceedings. There was no restriction of language or location.

SELECTION CRITERIA

Only published randomised trials of chemotherapy in HRPC patients were eligible for inclusion in this review. Randomised comparisons of different chemotherapeutic regimens, chemotherapy versus best standard of care or placebo, were relevant to this review. Randomised, dose-escalation studies were not included in this review.

DATA COLLECTION AND ANALYSIS

Data extraction tables were designed specifically for this review to aid data collection. Data from relevant studies were extracted and included information on trial design, participants, and outcomes. Trial quality was also assessed using a scoring system for randomisation, blinding, and description of patient withdrawal.

MAIN RESULTS

Out of 107 randomised trials of chemotherapy in advanced prostate cancer identified by the search strategy, 47 were included in this review and represented 6929 patients with HRPC. Only two trials compared the same chemotherapeutic interventions and therefore a meta-analysis was considered inappropriate. The quality of some trials was poor because of poor reporting, low-patient recruitment, or poor trial design. For clarity, trials were categorised according to the major drug used, but this was not a definitive grouping, since many trials used several agents and would be eligible for inclusion in a number of categories. Drug categories included estramustine, 5-fluorouracil, cyclophosphamide, doxorubicin, mitoxantrone, and docetaxel. Only studies using docetaxel reported a significant improvement in overall survival compared to best standard of care, although the increase was small (< 2.5 months). The mean percentage of patients achieving at least a 50% reduction in PSA compared to baseline was as follows: estramustine 48%; 5-fluorouracil 20%; doxorubicin 50% (one study only); mitoxantrone 33%; and docetaxel 52%. Pain relief was reported in 35% to 76% of patients receiving either single agents or combination regimens. A three weekly regime of docetaxel significantly improved pain relief compared to mitoxantrone plus prednisone (the latter regimen approved as standard therapy for HRPC in the USA). All chemotherapeutics, either as single agents or in combination, were associated with toxicity; the major ones being myelosuppression, gastrointestinal toxicity, cardiac toxicity, neuropathy, and alopecia. Quality of life was significantly improved with docetaxel compared to mitoxantrone plus prednisone.

AUTHORS' CONCLUSIONS

Patients with HRPC have not traditionally been offered chemotherapy as a routine treatment because of treatment-related toxicity and poor responses. Recent data from randomised studies, in particular those using docetaxel, have provided encouraging improvements in overall survival, palliation of symptoms, and improvements in quality of life. Chemotherapy should be considered as a treatment option for patients with HRPC. However, patients should make an informed decision based on the risks and benefits of chemotherapy.

Hypermethylation can selectively silence multiple promoters of steroid receptors in cancers

Multiple promoters and differential splicing of 5' upstream exons are often found in various nuclear receptor genes including steroid receptors. Three promoters control the expression of human estrogen receptor alpha (ERalpha) isoforms: ERalpha-A, ERalpha-B, and ERalpha-C, and two promoters control the expression of human progesterone receptor (PR) isoforms: PR-A and PR-B. The expression levels of these isoforms differ with respect to each other in certain target tissues. The role of these isoforms may differ in various types of cells and tissues. The ER and PR contain CpG islands in the 5' upstream regions. One possible mechanism for changing the transcriptional status is methylation of CpG-enriched regions in these isoforms. We have investigated the expression and methylation status of the three different ERalpha promoters and the two different PR gene promoters by using methylation specific PCR (MSP) and direct DNA sequencing in several endometrial and prostate cancer cell lines and tissues. The results of these experiments suggest that ERalpha-A, ERalpha-B, and PR-A were expressed and ERalpha-C and PR-B were inactivated in endometrial cancers. To the contrary, ERalpha-A and ERalpha-B were inactivated and ERalpha-C, PR-A and PR-B were expressed in all prostate cancer. Treatment with demethylating agent (5-aza-2'-deoxycytidine) restored these gene expressions, suggesting that inactivation of this gene is through methylation. Our MSP and direct DNA sequencing showed that ERalpha-A, ERalpha-B, and PR-A genes were unmethylated and ERalpha-C and PR-B were methylated in endometrial cancers although ERalpha-A and ERalpha-B were methylated and ERalpha-C, PRA and PRB were unmethylated in prostate cancers. These reports clearly demonstrate that selective hypermethylation can selectively silence multiple promoters of steroid receptors in carcinogenesis.

Hormone-refractory Prostate Cancer

For more than five decades, the preferred treatment for advanced prostate cancer has been suppression of androgen production by medical or surgical castration. However, all patients treated with androgen deprivation eventually develop resistant disease as manifested by increasing prostate-specific antigen levels, progressive disease on imaging studies, and ultimately worsening symptoms. The treatment of patients with hormone-refractory prostate cancer (HRPC), once thought to represent a relatively futile endeavor, has changed significantly in the past several years with the development of new therapeutics. One of the most important new treatment strategies involves secondary hormonal manipulation after the failure of primary androgen deprivation; this approach is predicated on the recognition that HRPC is a heterogenous disease. Some patients may respond to alternative hormonal interventions despite the presence of castrate levels of testosterone. Furthermore, the application of chemotherapeutic regimens has provided viable treatment options for patients with HRPC.

Treatment options in hormone-refractory prostate cancer: current and future approaches

Prostate cancer is the second leading cause of cancer mortality among men in Western countries. The initial treatment of advanced prostate cancer is suppression of testicular androgen production by medical or surgical castration, but nearly all men with metastases will develop disease progression. Patients with hormone refractory prostate cancer (HRPC) have a median survival of approximately 18 months and no therapy has yet demonstrated a definitive survival advantage. However, in the past several years, a number of promising new treatment strategies have emerged. One of the most important new treatment strategies involves secondary hormonal manipulation after the failure of primary androgen deprivation. This approach is predicated on the recognition that HRPC is a heterogeneous disease and some patients may respond to alternative hormonal interventions despite the presence of castrate levels of testosterone. Until recently, cytotoxic chemotherapy was felt to be relatively ineffective in the treatment of HRPC. Combination regimens incorporating new active agents have demonstrated significant activity in this setting, renewing interest in the use of chemotherapy to treat HRPC. Recent advances in the understanding of prostate cancer biology have led to the development of drugs directed against precise molecular alterations in the prostate tumour cell. Biologic agents now in development include those capable of altering signal transduction, blocking angiogenesis, inhibiting cell cycle progression, and stimulating apoptosis. In addition, many types of immune therapies are showing promise. Evaluating these agents, and incorporating them into existing regimens, are major goals of ongoing clinical research in advanced prostate cancer.

Secondary hormonal manipulations in hormone refractory prostate cancer

Hormone refractory prostate cancer is clinically heterogeneous, and many patients retain sensitivity to subsequent hormonal manipulations, even after combined androgen blockage. Antiandrogen withdrawal is a mandatory first step. Subsequent treatment with an alternate antiandrogen, adrenal androgen inhibitor (such as ketoconazole), or glucocorticoid may provide both subjective and objective clinical benefit in up to 65% of patients.

Hormone-refractory (D3) prostate cancer: refining the concept

OBJECTIVES

A wide range of responses have been reported to second-line hormonal therapies, including corticosteroids and the withdrawal of antiandrogens in patients with hormone-refractory prostate cancers. This suggested the need to classify patients on the basis of hormonal sensitivity. A schema was developed by assessing the differences in entry criteria in relation to outcomes for clinical protocols with hydrocortisone alone or in combination with other agents for patients who had progressed after primary hormone therapy.

METHODS

Published clinical trials of patients who had progressed after primary hormone treatment, which included glucocorticoids, were retrieved from Medline listings. The trials included patients treated with hydrocortisone alone, hydrocortisone and aminoglutethimide, hydrocortisone plus suramin, dexamethasone, and prednisone alone or in combination with chemotherapy.

RESULTS

The definitions used for refractory disease ranged from none, to "progression", to "unsuccessful second medical or surgical castration. "None of the trials included a definition for hormone-refractory disease based on objective criteria. Details were lacking on most trials with respect to the response to and specific types of hormonal therapies. Furthermore, few trials controlled for the potential contribution of the "flutamide withdrawal syndrome" on outcome.

CONCLUSIONS

The term "hormone-refractory" prostate cancer has evolved to include patients with a spectrum of diseases. As utilized in clinical trials of second-line hormonal therapies, patients who have received one and as many as six different treatments have been included in the same study. A new classification of patients based on hormonal sensitivity is proposed to recognize that androgen-independent proliferation, progression of disease despite castrate levels of testosterone, does not necessarily mean that a tumor is refractory to hormonal manipulations. Future trials in hormonally relapsed patients must include more details of the hormonal therapies utilized.

Prostate specific antigen levels and clinical response to low dose dexamethasone for hormone-refractory metastatic prostate carcinoma

BACKGROUND

It has been suggested that suppression of adrenal androgens may provide benefit to patients with metastatic prostate cancer refractory to initial hormonal therapy (e.g., orchiectomy).

METHODS

The records of 38 patients with metastatic prostate cancer that had progressed after orchiectomy who were placed subsequently on low dose dexamethasone (DXM) with no other concurrent therapy (36 patients received 0.75 mg twice daily and two received 0.75 mg three times daily) were reviewed. Symptomatic status, prostate specific antigen (PSA) measurements, and available radiographic assessments were recorded. Bone scans were reviewed by an independent, blinded evaluator.

RESULTS

Symptomatic improvement was experienced by 24 patients (63%), 20 (83%) of whom also had decreases in PSA. Prostate specific antigen values decreased in 30 patients (79%) with decreases 50% or greater and 80% or greater in 23 (61%) and 13 (34%) patients, respectively. Of the 23 patients with PSA decreases 50% or greater, 8 (35%) had radiographic evidence of disease regression, 5 (22%) were stable, 7 (30%) had disease progression, and 3 (13%) did not have serial radiographic exams. Flutamide was discontinued shortly before DXM treatment for 2 of the 23 patients.

CONCLUSIONS

Low dose DXM may produce important symptomatic improvement and decreased PSA levels in the majority of patients with hormone-refractory prostate cancer. In addition, a substantial percentage of those patients with decreases in PSA also will have radiographic evidence of disease regression. These results suggest the need for additional prospective controlled studies of DXM as a therapy for hormone-refractory prostate cancer.

Effects of estrogens and progestogens on the membrane permeability and growth of human prostatic carcinoma cells (PC-3) in vitro

The effects of estrogens and progestogens in the management of prostatic adenocarcinoma are generally believed to be related to their suppressive effect on the hypothalamic-pituitary-testicular axis, but other mechanisms have also been suggested. The present study was designed to investigate if an androgen-insensitive human prostatic cancer cell line (PC-3) is sensitive to estrogens or progestogens and to elucidate possible mechanisms of action. Both estrogens and progestogens in high doses (10(-5) M) suppressed tumor cell growth. At these high doses medroxyprogesterone acetate (MPA) most effectively reduced the uptake of 86rubidium chloride, indicating the strongest effect on ion transport and membrane permeability. Effects on rubidium transport were also seen after estrogen treatment. It is suggested that estrogens and progestogens have direct cytotoxic effects on prostatic carcinoma cells in vitro, possibly by an effect on the cell membrane.

Prostate cancer

Prostate cancer is the most common noncutaneous malignancy diagnosed in American men, and in 1994 it will pass lung cancer as the most common cancer diagnosed in the United States, with an estimated 200,000 new cases. The molecular biology of prostate carcinogenesis is rapidly advancing, and it is clear that, to a degree, prostate cancer is a heritable disease. The use of serum prostate-specific antigen (PSA) as a screening tool has been widely accepted by the medical community, although the evidence to support the efficacy of screening is not yet available. The curative approaches to organ-confined, clinically localized prostate cancer include radiation therapy, radical prostatectomy, and close observation in selected patients. The absence of well-designed clinical trials contributes to the confusion surrounding which curative treatment is the best option in individual patients. The standard approach to patients with evidence of extracapsular spread without distant metastases has been external-beam radiotherapy, although the results with radiation therapy alone in these patients has left considerable room for improvement. Innovative combined-modality approaches are currently being investigated at a number of institutions for these poor-prognosis patients. Three-dimensional conformal radiation therapy is currently being investigated at multiple institutions and offers some hope for improved results. The treatment of metastatic disease remains hormonal manipulation, although the exact nature of optimal androgen deprivation is currently a matter of considerable debate. In patients with hormone-refractory disease newer regimens using novel chemotherapy regimens offer some promise.