Effects of intravenous administration of high dose-diethylstilbestrol diphosphate on serum hormonal levels in patients with hormone-refractory prostate cancer

Luteinizing hormone-releasing hormone agonists versus orchiectomy in the treatment of prostate cancer: A systematic review

BACKGROUND

Orchiectomy has been replaced by medication represented by luteinizing hormone-releasing hormone (LHRH) agonist as the first-line therapy for androgen deprivation therapy (ADT). After the wide application of LHRH agonist, the side-effects of long-term ADT were noticed. It is time to reconsider the role of medication and surgeries in the treatment of prostate cancer.

METHODS

Embase, Pubmed, Web of science and Cochrane library were searched for relevant trials. Quality of the studies and risk of bias were assessed by using the Newcastle-Ottawa Scale (NOS). Therapeutic and adverse effects, as well as long-term metabolic adverse effects were extracted from the selected studies. The data synthesized in meta-analyses were performed with R software (4.2.1). Risk ratio (RR) with its 95% confidence interval (CI) was calculated by combining outcome data including complete and partial response rate, progression rate, death rate and adverse effects such as hot flash and increase in pain. Descriptive analysis was performed among the prostate specific antigen (PSA), testosterone and metabolic adverse effects due to a lack of homogeneity of frailty measures.

RESULTS

1,711 participants from 11 studies were included in our systematic review. 1,258 patients from six studies were included in the meta-analysis. Based on the meta-analysis, the therapeutic and adverse outcomes included overall response rate, complete response rate, partial response rate, stable rate, progression rate, death rate and hot flashes. No statistical significance was observed between LHRH agonists and orchiectomy. Compared with surgery, LHRH agonist elevated the risk of the increase in pain. In descriptive analysis, it was shown that the therapeutic effects between PSA and testosterone also showed no significant difference. Both groups had lipid and glucose metabolic disorders, and a few studies reported worse lipid metabolic performance in orchiectomy group and worse insulin resistance in LHRH agonist group.

CONCLUSION

We found that the therapeutic outcomes were similar between the two options. The results of lipid and glucose metabolic abnormality were controversial in existing studies. The direct comparison studies on metabolic adverse effects should be performed in the future. The therapeutic, metabolic, psychological and economical effects should be considered before applying ADT methods.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier CRD42022365891.

Glyphosate and the key characteristics of an endocrine disruptor: A review

Glyphosate is a large-spectrum herbicide that was introduced on the market in 1974. Due to its important impact on the crop industry, it has been significantly diversified and expanded being considered the most successful herbicide in history. Currently, its massive use has led to a wide environmental diffusion and its human consumption through food products has made possible to detect it in urine, serum, and breast milk samples. Nevertheless, recent studies have questioned its safety and international agencies have conflicting opinions about its effects on human health, mainly as an endocrine-disrupting chemical (EDC) and its carcinogenic capacity. Here, we conduct a comprehensive review where we describe the most important findings of the glyphosate effects in the endocrine system and asses the mechanistic evidence to classify it as an EDC. We use as guideline the ten key characteristics (KCs) of EDC proposed in the expert consensus statement published in 2020 (La Merrill et al., 2020) and discuss the scopes of some epidemiological studies for the evaluation of glyphosate as possible EDC. We conclude that glyphosate satisfies at least 8 KCs of an EDC, however, prospective cohort studies are still needed to elucidate the real effects in the human endocrine system.

Consensus on the key characteristics of endocrine-disrupting chemicals as a basis for hazard identification

Endocrine-disrupting chemicals (EDCs) are exogenous chemicals that interfere with hormone action, thereby increasing the risk of adverse health outcomes, including cancer, reproductive impairment, cognitive deficits and obesity. A complex literature of mechanistic studies provides evidence on the hazards of EDC exposure, yet there is no widely accepted systematic method to integrate these data to help identify EDC hazards. Inspired by work to improve hazard identification of carcinogens using key characteristics (KCs), we have developed ten KCs of EDCs based on our knowledge of hormone actions and EDC effects. In this Expert Consensus Statement, we describe the logic by which these KCs are identified and the assays that could be used to assess several of these KCs. We reflect on how these ten KCs can be used to identify, organize and utilize mechanistic data when evaluating chemicals as EDCs, and we use diethylstilbestrol, bisphenol A and perchlorate as examples to illustrate this approach.

Circulating steroid hormone variations throughout different stages of prostate cancer

Steroid hormones play a central role in the maintenance and progression of prostate cancer. The androgen receptor is the primary driver of tumor cell proliferation and is activated by the androgens testosterone and 5α-dihydrotestosterone. Inhibition of this pathway through medical or surgical castration improves survival in the majority of advanced prostate cancer patients. However, conversion of adrenal androgen precursors and alternative steroidogenic pathways have been found to contribute to tumor progression and resistance to treatment. The emergence of highly accurate detection methods allows us to study steroidogenic mechanisms in more detail, even after treatment with potent steroidogenic inhibitors such as the CYP17A1 inhibitor abiraterone. A clear overview of steroid hormone levels in patients throughout the local, metastatic and castration-resistant stages of prostate cancer and treatment modalities is key toward a better understanding of their role in tumor progression and treatment resistance. In this review, we summarize the currently available data on steroid hormones that have been implicated in the various stages of prostate cancer. Additionally, this review addresses the implications of these findings, highlights important studies in this field and identifies current gaps in literature.

Low-Dose Oral Ethinylestradiol With Concomitant Low-Dose Acetylsalicylic Acid for Advanced Castrate-Resistant Prostate Cancer

BACKGROUND

The aim of the present study was to evaluate the activity and tolerability of low-dose oral ethinylestradiol (EE) and luteinizing hormone-releasing hormone analogue with concomitant low-dose acetylsalicylic acid (ASA) as a thromboprophylactic agent for advanced castrate-resistant prostate cancer (CRPC).

PATIENTS AND METHODS

The patients received an EE dose of 150 μg daily (50 μg 3 times daily) and an ASA dose of 100 mg once daily. The primary endpoint was the prostate-specific antigen response.

RESULTS

A total of 32 patients were enrolled. A PSA response was observed in 19 patients (59.3%; 95% confidence interval [CI], 41%-76%). The median progression-free survival was 9.4 months (95% CI, 6.5-14.1 months). The treatment was generally well tolerated and no grade 3-4 toxicity was observed. Only 1 patient interrupted EE because of a cardiac event and 1 patient experienced grade 2 nausea and vomiting. No major bleeding occurred.

CONCLUSION

Low-dose EE with concomitant low-dose ASA is safe, showing potential activity in patients with advanced CRPC, and should be investigated further.

Suppression of liver Apo E secretion leads to HDL/cholesterol immaturity in rats administered ethinylestradiol

Ethinylestradiol (EE), a main component of the combined oral contraceptive pill, is associated with an increased risk of arterial diseases. However, the toxicity mechanism of EE is poorly understood. In this study, we found that the exposure to EE reduced the serum apolipoprotein E (Apo E) level and high-density lipoprotein (HDL)/cholesterol concentration in adult female rats. Diethylstilbestrol showed the same effects and both reductions were suppressed by coadministration of tamoxifen (TAM). Liver perfusion experiments revealed that the secretion rate of Apo E from the liver was significantly reduced. It is concluded that EE damages the maturation of HDL/cholesterol by delaying Apo E secretion from the liver, and this may lead to an increased risk of arterial diseases, such as atheromas.

Importance of Estrogenic Signaling and Its Mediated Receptors in Prostate Cancer

Prostate cancer (PCa) treatment was first established by Huggins and Hodges in 1941, primarily described as androgen deprivation via interference of testicular androgen production. The disease remains incurable with relapse of hormone-refractory cancer after treatments. Epidemiological and clinical studies disclosed the importance of estrogens in PCa. Discovery of estrogen receptor ERβ prompted direct estrogenic actions, in conjunction with ERα, on PCa cells. Mechanistically, ERs upon ligand binding transactivate target genes at consensus genomic sites via interactions with various transcriptional co-regulators to mold estrogenic signaling. With animal models, Noble revealed estrogen dependencies of PCa, providing insight into potential uses of antiestrogens in the treatment. Subsequently, various clinical trials were conducted and molecular and functional consequences of antiestrogen treatment in PCa were delineated. Besides, estrogens can also trigger rapid non-genomic signaling responses initiated at the plasma membrane, at least partially via an orphan G-protein-coupled receptor GPR30. Activation of GPR30 significantly inhibited in vitro and in vivo PCa cell growth and the underlying mechanism was elucidated. Currently, molecular networks of estrogenic and antiestrogenic signaling via ERα, ERβ and GPR30 in PCa have not been fully deciphered. This crucial information could be beneficial to further developments of effective estrogen- and antiestrogen-based therapy for PCa patients.

Adrenal steroidogenesis disruption caused by HDL/cholesterol suppression in diethylstilbestrol-treated adult male rat

The synthetic estrogen diethylstilbestrol is used to prevent miscarriages and as a therapeutic treatment for prostate cancer, but it has been reported to have adverse effects on endocrine homeostasis. However, the toxicity mechanism is poorly understood. Recently, we reported that diethylstilbestrol impairs adrenal steroidogenesis via cholesterol insufficiency in adult male rats. In the present study, we found that the adrenal cholesterol level was significantly reduced without of the decrease in other precursors in the adrenal steroidogenesis 24 h after a single dose of diethylstilbestrol (0.33 μg/g body mass). The serum HDL/cholesterol level was also reduced only 12 h after the diethylstilbestrol exposure. The level of Apo E, which is indispensable for HDL/cholesterol maturation, was decreased in both the HDL and VLDL/LDL fractions, whereas the level of Apo A1, which is an essential constituent of HDL, was not altered in the HDL fraction. Because the liver is a major source of Apo E and Apo A1, the secretion rates of these proteins were examined using a liver perfusion experiment. The secretion rate of Apo A1 from the liver was consistent between DES-treated and control rats, but that of Apo E was comparatively suppressed in the DES-treated rats. The disruption of adrenal steroidogenesis by diethylstilbestrol was caused by a decrease in serum HDL/cholesterol, which is the main source of adrenal steroidogenesis, due to the inhibition of Apo E secretion from the liver.

Diethylstilboestrol for the treatment of prostate cancer: past, present and future

The aim of this review was to discuss the most recent data from current trials of diethylstilboestrol (DES) to identify its present role in advanced prostate cancer treatment as new hormonal therapies emerge. The most relevant clinical studies using DES in castration-refractory prostate cancer (CRPC) were identified from the literature. The safety, efficacy, outcomes and mechanisms of action are summarized. In the age of chemotherapy this review highlights the efficacy of oestrogen therapy in CRPC. The optimal point in the therapeutic pathway at which DES should be prescribed remains to be established.

Transdermal estradiol in castrate and chemotherapy resistant prostate cancer

BACKGROUND

Given prior studies demonstrating the marked clinical activity of oral estrogens in prostate cancer, more recent data demonstrating the safety of transdermal estradiol, and the renewed interest in targeting testosterone metabolism and androgen receptor pathways, we report the results of a trial of transdermal estradiol in advanced heavily pre-treated castrate and chemotherapy refractory patients.

MATERIAL/METHODS

Patients with prostate cancer progressing after androgen ablation therapy and chemotherapy were treated with transdermal estradiol patches (0.4 mg per 24 hours total) applied weekly and assessed for tolerability and biochemical activity.

RESULTS

Twenty-two patients were treated on study with all patients evaluable for safety and 20 patients evaluable for response. All patients had aggressive and resistant disease, as demonstrated by a median PSA of 170 ng/mL (range 14 to 5030 ng/mL), with more than 60% having been treated with two or more prior chemotherapy regimens, and 20% with visceral disease. Nine patients had a decrease in PSA, of which two patients had a PSA response defined as a decline in PSA by 50%. Therapy was well tolerated and no thrombotic events were observed.

CONCLUSIONS

In heavily pre-treated patients with advanced castrate and chemotherapy refractory metastatic prostate cancer, transdermal estradiol was safe and had biochemical activity. These data support further studies to understand if transdermal estradiol can be useful following multiple standard therapies.

Preclinical characterization of a novel diphenyl benzamide selective ERα agonist for hormone therapy in prostate cancer

Androgen deprivation therapy (ADT) is the mainstay of treatment for advanced prostate cancer. ADT improves overall and disease-free survival rates, but long-term therapy is associated with severe side effects of androgen and estrogen depletion including hot flashes, weight gain, depression, and osteoporosis. Effective hormone reduction can be achieved without estrogen deficiency-related side effects by using therapy with estrogenic compounds. However, cardiovascular complications induced by estrogens coupled with the availability of LHRH agonists led to discontinuation of estrogen use for primary androgen deprivation therapy in the 1980s. New treatments for prostate cancer that improve patient outcomes without the serious estrogen deficiency-related toxicities associated with ADT using LHRH analogs are needed. Herein we describe a novel nonsteroidal selective estrogen receptor-α agonist designed for first-line therapy of advanced prostate cancer that in animal models induces medical castration and minimizes many of the estrogen deficiency-related side effects of ADT. The present studies show that orally administered GTx-758 reversibly suppressed testosterone to castrate levels and subsequently reduced prostate volume and circulating prostate-specific antigen in relevant preclinical models without inducing hot flashes, bone loss, thrombophilia, hypercoagulation, or increasing fat mass.

The effect of estrogen supplementation on cell proliferation and expression of c-kit positive cells in the rat prostate

BACKGROUND

Benign prostatic hyperplasia (BPH) is associated with the proliferation of prostate tissue and an increase in smooth muscle tone. However, the way in which the hormonal environment affects cell proliferation and prostatic interstitial cells (PIC) responsible for the maintenance of the smooth muscle tone is not clear. The present study investigated the effect of estrogen supplementation on cell proliferation, androgen/estrogen ratio, and expression and/or distribution of PIC.

METHODS

Male Sprague-Dawley rats were anesthetized with isoflurane/oxygen breathing mixture and subcutaneously implanted with silastic capsules. These capsules were either empty or filled with a 10 or 20 mg of crystalline estrogen.

RESULTS

Estrogen exerted a potent effect on ventral prostate weight, which was manifested as a significant decrease between controls and the E(10)- and E(20)-treated rats. Active cell proliferation detected as Ki67-positive nuclei was observed in the stromal and epithelial cells of the ventral prostatic lobes from estrogen-treated rats and controls. Estrogen supplementation caused a significant and dose-dependent increase in prostatic estradiol and 5alpha-dihydrotestosterone (DHT) concentration but the ratios of either DHT/E(2) or E(2)/DHT were not significantly affected. PIC were observed in the region between the fibromuscular stroma and the glandular epithelium in all three experimental groups. E(20)-treated rats showed a higher expression of PIC than controls and E(10)-treated rats.

CONCLUSIONS

The present study provides novel information regarding the synergistic role of estrogens and androgens in the prostate: estrogen may prevent prostatic hyperplasia via mechanisms other than affecting cell proliferation or DHT/estrogen ratio.

The mechanism of action of estrogen in castration-resistant prostate cancer: clues from hormone levels

BACKGROUND

Estrogen therapy plays a role in the management of castration-resistant prostate cancer (CRPC), although the mechanism of action is not fully known. This current analysis reports the relationship of change in adrenal androgen levels and prostate-specific antigen (PSA) response in patients with CRPC treated with estrogen therapy.

PATIENTS AND METHODS

Hormone levels were measured for patients with CRPC treated in a multicenter phase II trial of 2 estrogen-containing compounds, the herbal supplement PC-SPES and diethylstilbestrol (DES), with known efficacy in CRPC. Patients with castrate levels of testosterone were randomized to initially receive either PC-SPES 960 mg t.i.d. or DES 3 mg/day. Levels of testosterone, dihydrotestosterone (DHT), estradiol, estrone, sex hormone-binding globulin (SHBG), dehydroepiandrosterone (DHEA), DHEA-sulfate (DHEA-S), and androstenedione were obtained at baseline and at 12-week intervals until disease progression. Hormone levels were obtained for 38 patients, 20 treated with PC-SPES and 18 treated with DES.

RESULTS

Significant declines between baseline and 12 weeks of treatment were observed in levels of serum testosterone (P < .001), estrone (P = .02), and DHEA (P < .001). The percent changes at 12 weeks in these hormone levels were inversely proportional to baseline values as measured by Spearman's rank correlation (testosterone: -0.41, P = .01; estrone: -0.64, P = .0001; DHEA: -0.39, P = .02). Levels of SHBG increased in almost all of the patients (97%), with a median percent increase of > 5-fold (P < .0001). Of the 38 evaluable patients, 15 (39% [95% CI, 24%-57%]) experienced a > 50% decline in PSA level. There was no significant difference between treatment groups or between responders and nonresponders in baseline distributions for any of the hormones. At follow-up, 73% of the responders had a decline in the level of DHEA-S compared with 41% of the nonresponders, resulting in a difference in the distribution of the percent change between the subsets (Mann-Whitney test: P = .03). Conversely, 64% of the responders compared with 30% of the nonresponders experienced an increase in DHT, with differing distributions of percent change (P = .02).

CONCLUSION

Androgens decline in response to estrogen therapy. A decline in DHEA-S and a rise in DHT are both associated with a decline in PSA while patients receive estrogen therapy.

Androgen-Deprivation Therapy in Prostate Cancer: Clinical Evidence and Future Perspectives

Androgens are involved in the development and progression of prostate cancer even if the mechanism is not well-recognized. For this reason androgen-deprivation therapy remains a milestone for the treatment of patients with advanced and metastatic disease and, in the last years, in conjunction with radiotherapy and surgery in locally advanced tumors. Alternative options, such as intermittent deprivation suppression, seem to be promising in terms of clinical benefits and toxicity profile. However, current therapies present side effects, such as testosterone surge with consequent clinical flare-up, metabolic syndrome and hormone-resistance, which develops after a variable number of years. Novel therapies such as LH-RH antagonists and prolonged depot LH-RH analogues have been developed in order to avoid clinical flare-up and testosterone microsurges. Novel androgen synthesis inhibitors, such as abiraterone acetate and MDV3100, have been recently discovered and tested as promising hormonal second-line agents in patients with castration-resistant prostate cancer. Finally, long-term side effects from androgen deprivation, such as osteoporosis, sarcopenic obesity and cardiovascular morbidity should be carefully monitored and properly treated.

Redefining hormone resistance in prostate cancer

Prostate cancer relies on signaling through the androgen receptor (AR) for maintenance and progression; and androgen-deprivation therapy remains a cornerstone of treatment for advanced prostate cancer. An effective clinical classification of prostate cancer should account for the extent of the disease as well as the mechanisms that are driving the growth of the tumor. The previous terms hormone-sensitive and hormone-refractory described response to treatment. It has become clear that these terms do not reflect the mechanism of disease relapse; however over the last decade there has been a better understanding of androgen-receptor mediated signaling effects and incomplete suppression of androgens in prostate cancer. The Prostate Cancer Clinical Trials Working Group 2 (PCWG2) now recommends addressing the spectrum of clinical states based on castration status as this ligand-centered terminology can more accurately describe the patients' disease, and ultimately provides a useful framework for patient management and drug development. Optimized use of androgen-deprivation therapy, low molecular weight inhibitors of adrenal androgen biosynthesis, and new AR antagonists are promising new therapeutics that can further define the meaning of castrate state. As hormone resistance is redefined to include patients that are refractory to treatments that ablate adrenal and in situ tumoral androgens, a meaningful new clinical state in patients will be forged. We propose a model for incorporating these patients into the current PCWG2 conceptualization of the disease.

Activity of ketoconazole after taxane-based chemotherapy in castration-resistant prostate cancer

OBJECTIVE

To assess the efficacy of the androgen-synthesis inhibitor ketoconazole as a secondary hormonal therapy in patients with castration-resistant prostate cancer (CRPC) previously treated with chemotherapy, as persistent androgens appear to play a role in the development and maintenance of CRPC.

PATIENTS AND METHODS

We retrospectively identified 34 patients with CRPC who were treated with ketoconazole as a secondary hormonal therapy after paclitaxel- or docetaxel-based chemotherapy for CRPC. They were treated with ketoconazole 200-400 mg three times daily with or without hydrocortisone. Patients with previous use of ketoconazole were excluded. Half the patients had received estramustine as part of their chemotherapy regimen. The primary endpoint was the proportion of patients with a decline of > or =50% in their prostate-specific antigen (PSA) level. PSA progression was defined by the PSA Working Group 1 Criteria.

RESULTS

Eight of the 32 evaluable patients (25%) had a PSA decline of > or =50%. The median time to progression (TTP) was 3 months (95% confidence interval, 1.2-5.4). A history of previous response to taxane-based chemotherapy was not associated with the response to ketoconazole. However, previous use of oestrogens for CRPC was significantly associated with a shorter TTP on ketoconazole (1.5 vs 10.2 months; P = 0.03).

CONCLUSIONS

Ketoconazole has moderate activity as secondary hormonal therapy in patients with CRPC previously treated with taxane-based chemotherapy, although the TTP was short. Previous treatment with oestrogenic therapy is associated with a shorter TTP.

Starving the addiction: new opportunities for durable suppression of AR signaling in prostate cancer

Clinical data and models of human disease indicate that androgen receptor (AR) activity is essential for prostate cancer development, growth, and progression. The dependence of prostatic adenocarcinoma on AR signaling at all stages of disease has thereby been exploited in the treatment of disseminated tumors, for which ablation of AR function is the goal of first-line therapy. Although these strategies are initially effective, recurrent tumors arise with restored AR activity, and no durable treatment has yet been identified to combat this stage of disease. New insights into AR regulation and the mechanisms underlying resurgent AR activity have provided fertile ground for the development of novel strategies to more effectively inhibit receptor activity and prolong the transition to therapeutic failure.

Androgen deprivation therapy: progress in understanding mechanisms of resistance and optimizing androgen depletion

Androgen deprivation therapy remains a critical component of treatment for men with advanced prostate cancer, and data support its use in metastatic disease and in conjunction with surgery or radiation in specific settings. Alternatives to standard androgen deprivation therapy, such as intermittent androgen suppression and estrogen therapy, hold the potential to improve toxicity profiles while maintaining clinical benefit. Current androgen deprivation strategies seem to incompletely suppress androgen levels and androgen-receptor-mediated effects at the tissue level. Advances in the understanding of mechanisms that contribute to castration-resistant prostate cancer are leading to rationally designed therapies targeting androgen metabolism and the androgen receptor. The results of large trials investigating the optimization of primary androgen deprivation therapy, including evaluation of intermittent androgen suppression and phase III studies of novel androgen synthesis inhibitors, such as abiraterone acetate, are eagerly awaited.

Phase II Study of Low Dose and High Dose Conjugated Estrogen for Androgen Independent Prostate Cancer

PURPOSE

Although estrogens have known antitumor activity in androgen independent prostate cancer, the best studied agent, diethylstilbestrol, is no longer commercially available in the United States. We tested 2 doses of the conjugated estrogen Premarin(R) in patients with androgen independent prostate cancer to determine the efficacy and safety of this widely available medication.

MATERIALS AND METHODS

A total of 45 patients with progressive androgen independent prostate cancer were randomly assigned to receive Premarin 1.25 mg once (17) or 3 times (28) daily. Warfarin 1 mg daily was administered to all patients to minimize risk of thromboembolism. Low dose prophylactic breast irradiation was administered to most patients.

RESULTS

Of the patients receiving high dose Premarin 25% achieved a 50% or greater reduction in prostate specific antigen. No patients treated with low dose Premarin reached a 50% reduction in prostate specific antigen. After 3 months of treatment, 11 patients (39.3%) on the high dose arm and 6 patients (35.3%) on the low dose arm showed no signs of progression. Three patients (6.7%) had a thromboembolic event. No significant gynecomastia was noted. A significant difference in dehydroepiandrosterone sulfate levels was detected between those who did and did not respond to Premarin (p = 0.03).

CONCLUSIONS

High dose Premarin resulted in prostate specific antigen decreases of 50% or greater in 25% of patients with androgen independent prostate cancer. More than a third of patients receiving high or low dose Premarin maintained stable disease for at least 3 months. With concurrent warfarin 1 mg treatment, 6.7% experienced thromboembolic complications. Premarin 1.25 mg 3 times daily is a reasonable therapeutic option for patients with androgen independent disease.

Diethylstilbestrol and docetaxel

BACKGROUND

The addition of diethylstilbestrol to docetaxel modified tubulin composition and improved the response of prostate cancer to chemotherapy in preclinical models. An attempt was made to recapitulate the observations in a clinical trial.

METHODS

Twenty-nine patients with progressive, metastatic, chemotherapy-naive androgen-independent prostate cancer were treated with diethylstilbestrol 1 mg daily and 5 mg on the day before docetaxel and docetaxel 36 mg/m(2) intravenously weekly for 3 weeks of a 4-week cycle. Prophylactic anticoagulation was used in all patients. Patients were assessed by prostate-specific antigen (PSA) monthly and computed tomography (CT) and bone scans every 3 cycles. The Response Evaluation Criteria in Solid Tumors (RECIST) criteria and PSA decline by >50% maintained for 4 weeks were used to assess activity.

RESULTS

The median age was 68 years (range, 56-84 years), Southwest Oncology Group performance status 0 (score range, 0-2), alkaline phosphatase 120 U/L (range, 49-523), hemoglobin (Hgb) 12.6 g/dL (range, 9.2-16.3), PSA 66 ng/dL (range, 4-1962). The median number of cycles administered was 6. Soft tissue metastases were present in 51% of patients and bone metastases in 93%. Twenty-nine patients are evaluable for response. Of these, 20 patients (69%, 95% confidence interval [CI], 49%-85%) had a PSA decline of >50% and the PSA declined by >90% in 12 patients (41%, 95% CI, 23.1%-58.9%). Of 15 patients with measurable disease, 6 (40%, 95% CI, 23.5%-61%) had a partial response. Median time to progression was 6 months (range, 3-19 months). Fifteen patients (51%) suffered grade 3/4 toxicity. Two patients died of causes unrelated to therapy and another died from a steroid-induced ulcer. Six patients developed thrombosis and of those tested 75% had Factor V mutations. Pretreatment PSA, performance status, Hgb, and alkaline phosphatase had no impact on the likelihood of response.

CONCLUSIONS

The combination of diethylstilbestrol and docetaxel produces a significant level of activity, measured by PSA decline and measurable disease response rate, and except for venous thrombosis the toxicity appears similar to that seen with docetaxel plus prednisone. These results suggest that tubulin modulation with diethylstilbestrol may improve the therapeutic efficacy of docetaxel and the combination is worthy of further study.

A phase II multicenter, randomized, double-blind, safety trial assessing the pharmacokinetics, pharmacodynamics, and efficacy of oral 2-methoxyestradiol capsules in hormone-refractory prostate cancer

PURPOSE

To determine whether the preclinical antitumor and antiangiogenic activity of 2-methoxyestradiol can be translated to the clinic.

EXPERIMENTAL DESIGN

Men with hormone-refractory prostate cancer were enrolled into this phase II randomized, double-blind trial of two doses of oral 2-methoxyestradiol capsules (400 and 1,200 mg/d) given in 4-week cycles. Pharmacokinetic sampling was done on day 1 of cycles 1 and 2 and trough samples were obtained weekly.

RESULTS

Thirty-three men were accrued between February and September 2001. The notable toxicity related to therapy was one grade 2 and two grade 3 episodes of liver transaminase elevation, which resolved with continued treatment in two patients. There were two cases of deep venous thromboses. The drug had nonlinear pharmacokinetic, rapid conversion to 2-methoxyestrone and approximately 85% conjugation. Trough plasma levels of unconjugated 2-methoxyestradiol and 2-methoxyestrone were approximately 4 and 40 ng/mL, respectively. Prostate-specific antigen declines between 21% and 40% were seen in seven patients in the 1,200 mg group and in one patient in the 400 mg group. The higher-dose group showed significantly decreased prostate-specific antigen velocity (P = 0.037) and compared with the 400 mg dose had a longer median time to prostate-specific antigen progression (109 versus 67 days; P = 0.094) and time on study (126 versus 61 days; P = 0.024). There was a 2.5- and 4-fold increase in sex hormone-binding globulin for the 400 and 1,200 mg dose levels, respectively, at days 28 and 56.

CONCLUSION

2-Methoxyestradiol is well tolerated and, despite suboptimal plasma levels and limited oral bioavailability with this capsule formulation, still showed some anticancer activity at 1,200 mg/d.

Phase II study of transdermal estradiol in androgen-independent prostate carcinoma

BACKGROUND

Oral estrogen therapy has activity in patients with hormone-naive and androgen-independent prostate carcinoma (AIPC), but its utility is limited by the associated risk of thromboembolic toxicity. Parenteral administration may be safer as it avoids "first pass" liver exposure to estrogen. The authors tested the safety and efficacy of transdermal estradiol (TDE), as well as the effect of therapy on hot flashes, sex hormones, the procoagulant cascade, and bone turnover in patients with AIPC.

METHODS

Patients with prostate carcinoma progressing after primary hormonal therapy received TDE 0.6 mg per 24 hours (administered as six 0.1 mg per 24-hour patches replaced every 7 days). Serum prostate-specific antigen (PSA) and hormone levels, coagulation factors, markers of bone turnover, bone density measurements, and a hot flash diary were collected at regular intervals.

RESULTS

Three of 24 patients (12.5%; 95% confidence interval [CI], 0-26%) had a confirmed PSA reduction >50%. The Kaplan-Meier estimate of median time to disease progression was 12 weeks (95% CI, 4.6-19.4 weeks). Toxicity was modest and no thromboembolic complications occurred. The mean (+/-95% CI) serum estradiol level increased from 17.2 pg.mL (range, 14.8-19.6 pg/mL) to 460.7 pg/mL (range, 334.6-586.7 pg/mL). The total testosterone level remained stable in the anorchid range during treatment, but the free testosterone level decreased as a result of increased sex hormone binding globulin. No change in factor VIII activity, F 1.2, or resistance to activated protein C was observed, whereas a modest decrease in the protein S level was observed.

CONCLUSIONS

In patients with APIC, TDE was well tolerated and produced a modest response rate, but was not associated with thromboembolic complications or clinically important changes in several coagulation factors.

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

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

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.

The evolving role of estrogen therapy in prostate cancer

Estrogens, including diethylstilbestrol (DES), were used as the primary medical treatment for metastatic prostate cancer for many years but have been superceded in the past two decades by luteinizing hormone-releasing hormone (LHRH) agonists, primarily because of the cardiovascular toxicity associated with oral estrogen therapy. Recently, a renewed interest in estrogen therapy for prostate cancer in the United States has developed as a result of 3 major issues. First, when measured by declines in prostate-specific antigen of > or = 50%, clinical trials have demonstrated activity of DES, DES-diphosphate, and the estrogenic herbal therapy PC-SPES in 21%-86% of patients treated in phase II trials of androgen-independent prostate cancer patients. Second, the recent description of estrogen receptor (ER)-b has led to a reevaluation of the role of estrogens in normal prostate development and cancer pathogenesis. In contrast to ER-a, ER-b is strongly expressed in normal prostate epithelium. Furthermore, loss of ER-b expression has been demonstrated in prostate cancers, suggesting a possible role for this pathway in the development of cancer. Finally, the issues of cost and safety of estrogens are being reassessed in the current environment of rising health care costs and improved cardiovascular care. In Europe, estrogen therapy is more accepted as a low-cost and effective alternative to LHRH agonists and antiandrogens. Toxicity of DES and other estrogens has also been attenuated by strategies that use lower doses and parenteral routes of administration, thereby avoiding hepatic first-pass metabolism and decreasing the risk of thromboembolism. Nonetheless, there remain many unanswered questions about the role of estrogen therapy in prostate cancer, including differences between specific drugs, optimal dose, timing, and patient selection. Further research is needed.

Targeting FSH in androgen-independent prostate cancer: abarelix for prostate cancer progressing after orchiectomy

OBJECTIVES

To determine the efficacy of the gonadotropin-releasing hormone antagonist abarelix in patients with androgen-independent prostate cancer progressing after orchiectomy and to measure its effect on serum follicle-stimulating hormone (FSH).

METHODS

Sixteen patients with prostate cancer progressing after orchiectomy received abarelix-depot 100 mg by intramuscular injection on days 1, 15, and 29 and then every 28 days for up to 24 weeks (52 weeks in patients who met the criteria for a prostate-specific antigen [PSA] response after 24 weeks). PSA response was the primary endpoint and was defined as a 50% reduction confirmed 4 weeks later. The time to progression and effect of therapy on serum FSH were secondary endpoints.

RESULTS

No patient met the criteria for a PSA response. Five patients (31%, 95% confidence interval 11% to 58%) experienced confirmed reductions in the PSA level ranging from 9.3% to 31.8%. At the end of the six cycles of therapy, 6 patients remained stable without PSA progression or other signs of disease progression. The median time to progression was 12 weeks (95% confidence interval 6 to 18). The mean serum FSH concentration declined after 4 weeks of study treatment by nearly 90% from a baseline of 45.1 IU/L (95% confidence interval 34.0 to 56.2) and remained suppressed throughout the observation period. Treatment was well tolerated, with one grade 3 allergic reaction.

CONCLUSIONS

Treatment with abarelix in patients with androgen-independent prostate cancer after orchiectomy results in marked reduction in circulating FSH. None of the patients met the PSA response criteria; nonetheless, minor reductions in serum PSA were observed in 5 of 16 patients.

The nonsteroidal effects of diethylstilbestrol: the rationale for androgen deprivation therapy without estrogen deprivation in the treatment of prostate cancer

PURPOSE

During the last 2 decades there has been an increase in the number of men with prostate cancer placed on luteinizing hormone releasing hormone (LH-RH) agonist therapy. In addition, the duration of individual therapy has extended from what was once only a few months to, in many cases, several years. As a result there has been an increase in the incidence of side effects, including osteoporosis, decreased cognitive abilities, vascular stiffness and fatigue. We explored the use of estrogen in the form of diethylstilbestrol (DES) as an alternative treatment for men with prostate cancer, and introduce the concept of androgen deprivation without estrogen deprivation. In doing so we hope to elucidate some of the nonhormonal nonsteroidal effects of DES. Furthermore, we hope to define the mechanisms by which DES can be useful when LH-RH agonist therapy or orchiectomy has failed.

MATERIALS AND METHODS

We comprehensively reviewed the literature from 1935 to the present regarding estrogen and antiandrogen therapy. Our search focused on issues pertaining to side effects, efficacy and nonsteroidal effects of antiandrogens and estrogens.

RESULTS

It is readily apparent from the literature that androgen deprivation with DES can achieve effective prostate cancer control with demonstrable benefits compared to conventional LH-RH agonist therapy. In particular, rates of bone resorption and osteoporosis are less with the use of estrogen therapies. Estrogen has a clear beneficial effect on cognitive function. The estrogen metabolite 2-methoxyestradiol has significant antiangiogenic and pro-apoptotic effects. These effects give estrogens an added anticancer effect not otherwise seen in conventional LH-RH agonist therapy.

CONCLUSIONS

The efficacy of 1 mg DES extends well beyond its androgen suppressive effects. Androgen deprivation without estrogen deprivation is a concept that deserves further attention in the urological community.

The role of diethylstilbestrol in the treatment of prostate cancer

OBJECTIVES

Diethylstilbestrol administration was a classic form of androgen deprivation therapy (ADT) that gradually fell out of favor because of its cardiovascular toxicity, economic disinterest on the part of manufacturers, and the emergence of novel therapeutic agents with a superior safety profile. The cost of contemporary agents and the efficacy of diethylstilbestrol (DES) have perpetuated the evaluation of this agent, especially in the circumstance of early hormone-refractory (clinical stage D2.5) disease. The objective of this study is to evaluate the status of DES-based therapies, and assess their efficacy and toxicity as a viable form of ADT.

METHODS

Current research from single-institution and group studies, as well as basic scientific investigations related to DES, were assessed with regard to the population studied, dosage, criteria for response, response rate, duration of response, and toxicity.

RESULTS

Contemporary basic research has demonstrated a direct apoptotic effect of DES on prostate cancer cells. There is also evidence to support the ability of DES to suppress testosterone production at extratesticular sites and inhibit dihydroepiandrosterone sulfate serum levels. Contemporary cooperative group trials for stage D2 disease incorporating a DES arm have demonstrated therapeutic efficacy and equivalence to orchiectomy, which is marred by significant cardiovascular toxicity. In smaller single-institution studies (n = 17 to 38) of patients with D2.5 disease, an average response rate of 55% is noted with a mean time to clinical progression of 6.4 months (2 to 18). Cardiovascular toxicity occurred in 10% to 30% of patients, with events including deep vein thrombosis, myocardial infarction, and transient ischemic attack. Edema and gynecomastia was also noted. Strategies to reduce thromboembolic events, such as dose reduction or the use of warfarin sodium were unsuccessful, whereas the use of low-dose aspirin (100 mg daily) resulted in only 1 of 38 vascular events.

CONCLUSIONS

In contemporary studies of DES as an agent for ADT in D2.5 patients, a reasonable response rate (40% to 60%) of modest duration (5 to 8 months) is noted. Cardiovascular complications still persist, requiring the development of safe, effective antithrombolic therapy to take advantage of this phenomenon.