Cardiovascular follow-up of patients with prostatic cancer treated with single-drug polyestradiol phosphate

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.

Significance of pretreatment cardiovascular morbidity as a risk factor during treatment with parenteral oestrogen or combined androgen deprivation of 915 patients with metastasized prostate cancer: evaluation of cardiovascular events in a randomized trial

OBJECTIVE

This study aimed to evaluate prognostic risk factors for cardiovascular events during treatment of metastatic prostate cancer patients with high-dose parenteral polyoestradiol phosphate (PEP, Estradurin®) or combined androgen deprivation (CAD) with special emphasis on pretreatment cardiovascular disease.

MATERIAL AND METHODS

Nine-hundred and fifteen patients with T0-4, Nx, M1, G1-3, hormone- naïve prostate cancer were randomized to treatment with PEP 240 mg i.m. twice a month for 2 months and thereafter monthly, or to flutamide (Eulexin®) 250 mg per os three times daily in combination with either triptorelin (Decapeptyl®) 3.75 mg i.m. per month or on an optional basis with bilateral orchidectomy. Pretreatment cardiovascular morbidity was recorded and cardiovascular events during treatment were assessed by an experienced cardiologist. A multivariate analysis was done using logistic regression.

RESULTS

There was a significant increase in cardiovascular events during treatment with PEP in patients with previous ischaemic heart disease (p = 0.008), ischaemic cerebral disease (p = 0.002), intermittent claudication (p = 0.031) and especially when the whole group of patients with pretreatment cardiovascular diseases was analysed together (p < 0.001). In this group 33% of the patients had a cardiovascular event during PEP treatment. In the multivariate analysis PEP stood out as the most important risk factor for cardiac complications (p = 0.029). Even in the CAD group there was a significant increase in cardiovascular events in the group with all previous cardiovascular diseases taken together (p = 0.036).

CONCLUSIONS

Patients with previous cardiovascular disease are at considerable risk of cardiovascular events during treatment with high-dose PEP and even during CAD therapy. Patients without pretreatment cardiovascular morbidity have a moderate cardiovascular risk during PEP treatment and could be considered for this treatment if the advantages of this therapy, e.g. avoidance of osteopenia and hot flushes and the low price, are given priority.

Parenteral estrogen versus combined androgen deprivation in the treatment of metastatic prostatic cancer: part 2. Final evaluation of the Scandinavian Prostatic Cancer Group (SPCG) Study No. 5

OBJECTIVE

To compare parenteral estrogen therapy in the form of high-dose polyestradiol phosphate (PEP; Estradurin) with combined androgen deprivation (CAD) in the treatment of prostate cancer patients with skeletal metastases. The aim of the study was to compare anticancer efficacy and adverse events, especially cardiovascular events.

MATERIAL AND METHODS

In total, 910 eligible patients with T0-4, NX, M1, G1-3 prostate cancer with an Eastern Cooperative Oncology Group performance status of 0-2 were randomized to treatment with either PEP 240 mg i.m. twice a month for 2 months and thereafter monthly, or flutamide (Eulexin) 250 mg t.i.d. per os in combination with either triptorelin (Decapeptyl) 3.75 mg i.m. per month or on an optional basis bilateral orchidectomy.

RESULTS

At this final evaluation of the trial 855 of the 910 patients were dead. There was no difference between the treatment groups in terms of biochemical or clinical progression-free survival or in overall or disease-specific survival. There was no difference in cardiovascular mortality, but a significant increase in non-fatal cardiovascular events in the PEP arm (p<0.05) predominantly caused by an increase in ischemic heart and heart decompensation events. There were 18 grave skeletal events in the CAD group but none in the PEP group (p=0.001).

CONCLUSIONS

PEP has an anticancer efficacy equal to CAD and does not increase cardiovascular mortality in metastasized patients, but carries a significant risk of non-fatal cardiovascular events, which should be balanced against the skeletal complications in the CAD group. It is feasible to use Estradurin in the primary or secondary endocrine treatment of metastasized patients without prominent cardiac risk factors and especially those with osteoporosis.

Parenteral oestrogen in the treatment of prostate cancer: a systematic review

The objectives of this study were to assess the effectiveness and safety of parenteral oestrogen in the treatment of prostate cancer, and to examine any dose relationship. A systematic review was undertaken. Electronic databases, published paper and internet resources were searched to locate published and unpublished studies with no restriction by language or publication date. Studies included were randomised controlled trials of parenteral oestrogen in patients with prostate cancer; other study designs were also included to examine dose-response. Study selection, appraisal, data extraction and quality assessment were performed by one reviewer and independently checked by another. Twenty trials were included in the review. The trials differed with regard to the included patients, formulation and dose of parenteral oestrogen, comparator used, outcome measures reported and the duration of follow-up. The results provide no evidence to suggest that parenteral oestrogen, in doses sufficient to produce castrate levels of testosterone, is less effective than luteinising hormone-releasing hormone (LHRH) or orchidectomy in controlling prostate cancer, or that it is consistently associated with an increase in cardiovascular mortality. Further well-conducted trials of parenteral oestrogen are required. A pilot randomised controlled trial comparing transdermal oestrogen to LHRH analogues in men with locally advanced or metastatic prostate cancer is underway in the United Kingdom.

Parenteral Estrogens for Prostate Cancer: Can a New Route of Administration Overcome Old Toxicities?

Androgen deprivation therapy (ADT) is the mainstay of management of advanced-stage prostate cancer and recently has been shown to improve survival when administered in earlier stages of the disease. The oncologic benefits of ADT might be partially offset, however, by a reduction in quality of life because of adverse effects. In addition to the well-recognized adverse consequences of ADT, recent evidence suggests that ADT is associated with dyslipidemia, impaired glucose metabolism, adverse body compositional changes, and osteoporosis. Therefore, there is a pressing need to develop less toxic forms of ADT. A novel approach to this problem is the use of estrogen to induce androgen suppression. Whereas oral estrogen therapy is known to be associated with thromboembolic complications, studies of parenteral estrogen in men with prostate cancer suggest that the use of parenteral estrogen achieves target androgen suppression, does not adversely affect prothrombotic protein levels, and is not associated with adverse metabolic, skeletal, and body compositional changes when compared with conventional ADT. Herein, we review the data for parenteral estrogen use in prostate cancer, the antineoplastic mechanisms of action of estrogen in prostate cancer, the potential advantages of parenteral estrogen compared with conventional ADT, and the remaining barriers in the use of parenteral estrogen in prostate cancer.

Therapy Insight: parenteral estrogen treatment for prostate cancer—a new dawn for an old therapy

Oral estrogens were the treatment of choice for carcinoma of the prostate for over four decades, but were abandoned because of an excess of cardiovascular and thromboembolic toxicity. It is now recognized that most of this toxicity is related to the first pass portal circulation, which upregulates the hepatic metabolism of hormones, lipids and coagulation proteins. Most of this toxicity can be avoided by parenteral (intramuscular or transdermal) estrogen administration, which avoids hepatic enzyme induction. It also seems that a short-term but modest increase in cardiovascular morbidity (but not mortality) is compensated for by a long-term cardioprotective benefit, which accrues progressively as vascular remodeling develops over time. Parenteral estrogen therapy has the advantage of giving protection against the effects of andropause (similar to the female menopause), which are induced by conventional androgen suppression and include osteoporotic fracture, hot flashes, asthenia and cognitive dysfunction. In addition, parenteral estrogen therapy is significantly cheaper than contemporary endocrine therapy, with substantive economic implications for health providers.

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.

Parenteral estrogen versus total androgen ablation in the treatment of advanced prostate carcinoma: effects on overall survival and cardiovascular mortality. The Scandinavian Prostatic Cancer Group (SPCG)-5 Trial Study

OBJECTIVES

To compare the effect on overall survival of total androgen ablation (TAA) with that of parenteral estrogen and to pay special attention to cardiovascular mortality. TAA (orchiectomy or a luteinizing hormone-releasing hormone analogue combined with an antiandrogen) has been proposed as superior to other endocrine treatments for patients with prostate carcinoma. Recently, the use of parenteral estrogen has been suggested to reduce or even negate the well-known cardiovascular side effects of oral estrogens.

METHODS

Nine hundred fifteen patients were randomized to intramuscular injections of 240 mg polyestradiol phosphate (PEP) every second week for the first 8 weeks (5 doses) followed by a maintenance dose of 240 mg every month (n = 458) or to bilateral orchiectomy or triptorelin 3.75 mg every month combined with the antiandrogen flutamide 250 mg three times daily. The choice between orchiectomy and triptorelin was at the discretion of the clinician and patient. Patients were stratified according to performance status, presence of cardiovascular disease, and alkaline phosphatase level. An observer totally unaware of the treatment given classified all deceased patients.

RESULTS

At a median follow-up of 18.5 months, no signs of a difference in overall survival were found between TAA and PEP (P <0.001). Of 458 patients, 266 (58.1%) had died in the PEP group compared with 269 (58.9%) of 457 patients in the TAA group. Within the TAA group, no difference in overall survival existed between patients who had undergone orchiectomy or who were given triptorelin. Furthermore, no differences in cardiovascular mortality were found (3.5% in the PEP group and 3.1% in the TAA group).

CONCLUSIONS

The current parenteral estrogen regimen seems to be of comparable efficacy and cardiovascular safety as TAA in terms of overall survival. PEP has by far the lowest drug cost and also the lowest cumulative direct costs and thus has the highest cost-effectiveness. We suggest that parenteral estrogen be included as a therapeutic option in the endocrine management of prostate carcinoma.

Time for revival of estrogens in the treatment of advanced prostatic carcinoma? Pharmacokinetics, and endocrine and clinical effects, of a parenteral estrogen regimen

BACKGROUND

The present pilot study tested the clinical performance of a new pharmacokinetically guided dosing regimen of parenteral estrogen in patients with advanced prostatic carcinoma. The aim was to accelerate endocrine effects and to avoid cardiovascular side effects.

METHODS

Seventeen patients were randomized to intramuscular injections of 240 mg polyestradiol phosphate (PEP) every second week for the first 8 weeks (five doses), followed by a maintenance dose of 240 mg every month; and 16 patients were randomized to bilateral orchidectomy. The estrogen dosing was calculated by pharmacokinetic modelling to achieve a rapid increase in serum estradiol and thereby a fast decrease in testosterone.

RESULTS

The predicted increment in serum estrogen was achieved, together with a subsequent decrease in testosterone in the PEP group. In addition, there were no signs of an increased cardiovascular morbidity. This was probably due to a minimal estrogenic influence on the liver and was reflected by unchanged levels of coagulation factor VII. Clinical effects, during the first 2 years of treatment, were similar in the two treatment arms, with 12 patients in the orchidectomy group and 14 patients in the PEP group responding to treatment.

CONCLUSIONS

The present parenteral regimen is an efficient and time-saving estrogen regimen with a favorable side-effect profile. PEP seems to offer a potential for revival of the most cost-effective endocrine treatment of cancer of the prostate, i.e., estrogen.

Pharmacokinetics and testosterone suppression of a single dose of polyestradiol phosphate (Estradurin) in prostatic cancer patients

The pharmacokinetics and endocrine effects of polyestradiol phosphate (PEP; Estradurin) were studied by determination of the concentrations of estradiol (E2), unconjugated (E1) and total estrone (tE1; > or = 85% estrone sulfate), and testosterone in serum from 11 prostatic cancer patients after administration of a single intramuscular injection (320 mg). After injection of PEP, serum concentrations of E2, E1, and tE1 increased during 2-3 weeks. Thereafter serum E2 declined monophasically with a mean half-life of 70 days. The elimination of E1 and tE1 seemed to be governed by the formation of E2. The testosterone concentration decreased inversely to the raising E2 level and reached castration levels within 3 weeks and remained at this level for about 2 weeks, whereafter it increased inversely to the decreasing E2 concentrations.

The T61 human breast cancer xenograft: an experimental model of estrogen therapy of breast cancer

Endocrine therapy is one of the principal treatment modalities of breast cancer, both in an adjuvant setting and in advanced disease. The T61 breast cancer xenograft described here provides an experimental model of the effects of estrogen treatment at a molecular level. T61 is an estrogen receptor positive tumor which was originally derived from a T1N0M0 invasive ductal cancer and has been carried as a serially transplanted xenograft in nude mice. T61 is a hormone sensitive tumor whose growth is suppressed by both estrogen and tamoxifen, in contrast to other estrogen receptor positive tumors such as MCF-7 which are stimulated by estrogen. Molecular studies have demonstrated that T61 expresses easily detectable levels of mRNA for a number of peptide growth factors, including transforming growth factor alpha (TGF-alpha) and insulin-like growth factors I and II (IGF-I and IGF-II), but not transforming growth factor beta-I (TGF-beta1). Of these, IGF-II is the only peptide whose expression is altered by endocrine therapy. Treatment of T61-bearing nude mice with physiologic doses of estrogen is accompanied by loss of IGF-II mRNA expression within 24 hours, and rapid regression of tumor. T61 tumor growth is also inhibited in animals treated with a monoclonal antibody which blocks binding of ligand to the IGF-I receptor, which mediates the mitogenic signal of bound IGF-II through autophosphorylation of its intracellular tyrosine kinase domain. These results demonstrate the utility of the T61 model in the study of the molecular mechanism of estrogen therapy in breast cancer, and suggest that in this system, modulation of a specific growth factor (IGF-II) by endocrine therapy can have profound effects on tumor growth.

High-dose continuous-infusion fosfestrol in hormone-resistant prostate cancer

BACKGROUND

The initial treatment of advanced-stage prostate cancer is total androgen deprivation. Autonomous proliferation of primarily or secondarily hormonal unresponsive cells may explain the development of hormone-refractory status. The median survival of patients with hormone-resistant disease is short; there is no standard regimen of chemotherapy.

METHODS

Fosfestrol or diethylstilbestrol diphosphate and its metabolites have cytotoxic activity in hormone-refractory prostatic cell lines. Pharmacokinetic studies have shown that fosfestrol metabolites have a short half-life that supports the use of long-term infusion in the clinic.

RESULTS

A review of the literature shows that high-dose fosfestrol induces no objective response, a greater than 50% tumor marker decrease in 50% of patients, a subjective improvement in 75% of patients, and cardiovascular complications in 5% of patients. The median survival time of patients is 5 months after the onset of treatment.

CONCLUSIONS

An exact evaluation of the role of high-dose estrogens requires additional investigation.

Cardiovascular and all-cause mortality in prostatic cancer patients treated with estrogens or orchiectomy as compared to the standard population

Four hundred and seventy-seven prospectively randomized patients with prostatic carcinoma were treated with a combination of intramuscular polyestradiol phosphate (PEP) and oral ethinyl estradiol, with intramuscular PEP alone, or with orchiectomy. The cardiovascular and all-cause mortality of the two estrogen therapy modalities and orchiectomy were compared with those of the Finnish male population in general. The age-standardized rate ratios (approximately relative risk) for cardiovascular mortality and for all-cause mortality were 1.51 and 2.31 in the combination estrogen therapy group, 0.17 and 1.50 in the PEP monotherapy group, and 0.78 and 1.78 in the orchiectomy group, respectively. Further mortality rates by cause for all three treatment groups were standardized for age using the age-specific person-years at risk as standard. Age-standardized mortality from cardiovascular diseases was very low in the PEP group, as compared to other treatment modalities, and the mortality rates for prostatic cancer were about equal in all three treatment groups. It is concluded that intramuscular PEP monotherapy is associated with low cardiovascular mortality and with an all-cause and prostatic cancer mortality equal to orchiectomy.

Cost comparison of parenteral estrogen and conventional hormonal treatment in patients with prostatic cancer

The present study compares the cost of antitumor therapy and adverse cardiovascular effects during the first year of treatment with oral estrogens, nonoral estrogens, or surgical castration in patients with prostatic cancer. We found a much higher cost for patients treated with orchidectomy and oral estrogens than for patients treated with nonoral estrogens. Twenty-five percent of the patients treated with oral estrogen suffered cardiovascular complications, compared to none of the patients treated by orchidectomy or nonoral estrogens. The initial cost of orchidectomy as compared to nonoral estrogen treatment was shown not be balanced within the expected survival time of patients with advanced prostatic cancer. Furthermore, surgical castration causes psychological trauma to the patient. We recommend parenteral estrogen therapy as a low-cost therapeutic regimen in patients with prostatic cancer.

Effect of parenteral oestrogen on the coagulation system in patients with prostatic carcinoma

Patients with prostatic carcinoma on oral oestrogen therapy have an altered coagulation system and suffer cardiovascular side effects. Oestrogens--especially oral oestrogens--are potent inducers of liver synthesised proteins, including coagulation factors. We have assessed the effect of non-oral oestrogen on the coagulation system in patients with prostatic carcinoma. Twelve patients were given monthly intramuscular injections of 320 mg polyoestradiol phosphate (PEP). No additional oestrogens were given. No change was found in any of the coagulation factors, including factor VII, with the exception of a significant decrease in antithrombin III. No patient, including 38 patients treated with PEP, had any cardiovascular complications after a mean follow-up period of 12.9 +/- 0.7 months; 76% of the patients responded to treatment. Parenteral administration of oestrogen caused a less marked change in the coagulation system than oral administration and should be the treatment of choice for prostatic carcinoma.

Estrogen therapy and liver function--metabolic effects of oral and parenteral administration

Oral estrogen therapy for prostatic cancer is clinically effective but also accompanied by severe cardiovascular side effects. Hypertension, venous thromboembolism, and other cardiovascular disorders are associated with alterations in liver metabolism. The impact of exogenous estrogens on the liver is dependent on the route of administration and the type and dose of estrogen. Oral administration of synthetic estrogens has profound effects on liver-derived plasma proteins, coagulation factors, lipoproteins, and triglycerides, whereas parenteral administration of native estradiol has very little influence on these aspects of liver function.

Clinical pharmacology of polyestradiol phosphate

The results of the present studies demonstrate that intramuscular injections of polyestradiol phosphate (PEP) produce not only considerably increased estrogen concentration in plasma but also maintain the same estrone/estradiol ratio as in normal men. Monthly injections of PEP produce persistent elevation of the plasma estradiol levels throughout the dose interval, and rising PEP doses produce proportionately increasing steady-state plasma concentrations of estradiol. The steady-state plasma concentrations of testosterone are reduced to 45, 25, and 15% of the pretreatment concentrations after treatment every fourth week with 80, 160, and 240 mg PEP, respectively.