Prostatic cancer and SCH-13521: II. Histological alterations and the pituitary gonadal axis

The DHEA-sulfate depot following P450c17 inhibition supports the case for AKR1C3 inhibition in high risk localized and advanced castration resistant prostate cancer

Prostate cancer is the second leading cause of cancer death in the United States. Treatment of localized high-risk disease and de novo metastatic disease frequently leads to relapse. These metastatic castration resistant prostate cancers (mCRPC) claim a high mortality rate, despite the extended survival afforded by the growing armamentarium of androgen deprivation, radiation and immunotherapies. Here, we review two studies of neoadjuvant treatment of high-risk localized prostate cancer prior to prostatectomy, the total androgen pathway suppression (TAPS) trial and the neoadjuvant abiraterone acetate (AA) trial. These two trials assessed the efficacy of the non-specific P450c17 inhibitor, ketoconazole and the specific P450c17 inhibitor, AA, to inhibit tissue and serum androgen levels. Furthermore, a novel and validated stable isotope dilution liquid chromatography electrospray ionization selected reaction monitoring mass spectrometry assay was used to accurately quantify adrenal and gonadal androgens in circulation during the course of these trials. The adrenal androgens, Δ(4)-androstene-3,17-dione, dehydroepiandrosterone and dehydroepiandrosterone sulfate were significantly reduced in the patients receiving ketoconazole or AA compared to those who did not. However, in both trials, a significant amount of DHEA-S (∼20 μg/dL) persists and thus may serve as a depot for intratumoral conversion to the potent androgen receptor ligands, testosterone (T) and 5α-dihydrotestosterone (DHT). The final step in conversion of Δ(4)-androstene-3,17-dione and 5α-androstanedione to T and DHT, respectively, is catalyzed by AKR1C3. We therefore present the case that in the context of the DHEA-S depot, P450c17 and AKR1C3 inhibition may be an effective combinatorial treatment strategy.

Hormone therapy of prostate cancer: is there a role for antiandrogen monotherapy?

Androgen suppressive maneuvers still represent the gold standard for prostate cancer patients. However, they are associated with side effects (fatigue, sexual impotence, hot flushes, anemia, anxiety, depression and osteoporosis) all of which have a negative impact on quality of life. Nonsteroidal antiandrogens compete with dihydrotestosterone for the linkage of its own receptors. These compounds are commonly used in combination with suppressive maneuvers. However, there is a growing experience with them as monotherapy, based on the possibility to spare gonadal function and therefore prevent the effects related to its suppression. Many studies have demonstrated the feasibility and safety of this approach, which can represent a valuable alternative to suppressive maneuvers for patients wishing to retain sexual function, especially for those without distant metastases. Unfortunately, none of the comparative studies performed so far had the power to detect the equivalence between monotherapy and castration.

Tamoxifen for flutamide/finasteride-induced gynecomastia

OBJECTIVES

Current therapies for advanced prostate carcinoma lead to a marked decrease in serum testosterone levels, which renders patients impotent. In preliminary studies, combination therapy with flutamide and finasteride has been used as an alternative therapy for the treatment of prostate carcinoma because potency can be preserved. Both of these agents can cause gynecomastia and breast/nipple tenderness.

METHODS

Six men being treated for advanced prostate carcinoma with flutamide/finasteride combination therapy developed painful gynecomastia, which was treated with tamoxifen 10 to 30 mg/day for 1 month. Clinical follow-up included breast measurements and determination of prostate-specific antigen (PSA), testosterone, and estradiol levels.

RESULTS

While on this combination therapy for prostate carcinoma, 4 of 6 patients experienced a decrease in PSA level to less than 0.5 ng/mL. All patients remained potent. Serum testosterone increased in each patient who had a baseline level drawn. Estradiol levels were noted to be elevated in 4 of 6 patients at the time of evaluation for gynecomastia. After treatment with tamoxifen, circulating estradiol levels increased in 3 patients from 1.3 to 2.2 times the baseline level. Five patients experienced complete resolution of breast and nipple pain on tamoxifen 10 mg/day within the first month. The other patient had to be treated with 30 mg/day for 1 additional month, which subsequently resulted in pain resolution.

CONCLUSIONS

These preliminary results suggest that low-dose tamoxifen is useful in treating painful gynecomastia for those patients on flutamide/finasteride combination therapy for advanced prostate carcinoma.

Clinical and endocrine effects of flutamide in hyperandrogenic women

OBJECTIVE

To investigate the clinical and endocrine effects of the antiandrogen flutamide in hirsute women.

DESIGN

Hirsutism was assessed before and after 3 months of treatment with flutamide 500 mg/d. Endocrine evaluations were performed before and during the 2nd month of treatment with flutamide 500 mg or 750 mg/d.

SETTING

Department of Obstetrics and Gynecology, Pisa, Italy.

PARTICIPANTS

Eighteen hirsute women were studied: nine women were hyperandrogenic, and the other 9 had an idiopathic hirsutism.

INTERVENTIONS

Women were randomly treated with flutamide 500 mg/d (9 patients) or 750 mg/d (9 patients) for 3 and 2 months, respectively. Six received placebo 1 month before flutamide treatment.

MAIN OUTCOME MEASURES

Hirsutism was assessed by measuring hair diameter. Follicle-stimulating hormone and LH responses to GnRH were evaluated. Basal plasma levels of T, androstenedione (A), 17-hydroxyprogesterone (17-OHP), DHEAS, cortisol (F), and sex hormone-binding globulin (SHBG) were evaluated. The same hormones were determined after a single dose of flutamide (250 or 500 mg) or placebo throughout a 12-hour period and in samples collected 60 and 120 minutes after ACTH intravenous injection.

RESULTS

Hair diameter was reduced by 30%. Both dosages of flutamide did not change basal and stimulated gonadotropin, T, A, 17-OHP, F, and SHBG levels. Both dosages reduced stimulated DHEAS levels.

CONCLUSIONS

Flutamide may have a beneficial effect on hirsutism. This effectiveness is mainly due to its peripheral antiandrogen action. However, an effect on the adrenal gland seems to be present.

Antiandrogenic drugs

BACKGROUND

Prostate cancer is the most frequent cancer diagnosed in American men today. Currently, about half of all patients with newly diagnosed prostate cancer present with metastatic diseases.

METHODS

Antiandrogenic drugs, or more appropriately androgen-receptor antagonists, represent a group of compounds that currently have played a limited role in the treatment of metastatic prostate cancer. Their method of action is primarily one of blocking androgens at their receptor sites in target tissues. They generally are classified as steroidal or nonsteroidal compounds. Cyproterone acetate and megestrol acetate are synthetic steroidal antiandrogenic drugs that, not only compete with testosterone and dihydrotestosterone for androgen receptors, but also have progestational activity and reduce pituitary luteinizing hormone and subsequently plasma testosterone. Nonsteroidal antiandrogenic agents (flutamide, Casodex [ICI Pharmaceuticals, England], and nilutamide) block cellular binding of androgens only, and there is no reduction of testosterone levels.

RESULTS

Antiandrogenics have been used in numerous trials both in Europe and the United States. This group of compounds have been used as monotherapy and in combination therapy, ie, with orchiectomy or with LHRH agonists.

CONCLUSIONS

Currently, antiandrogens are used primarily in conjunction with conventional medical or surgical castration to achieve maximal androgen deprivation; however, ongoing clinical studies are comparing these compounds alone against standard hormonal therapy. It seems probable that antiandrogens will play an expanding role in the treatment of metastatic prostate cancer as well as having a role in the treatment of prostate cancer.

A rationale for the use of non-steroidal anti-androgens in the management of prostate cancer

Flutamide is a non-steroidal anti-androgen which has been used to treat prostate cancer. Results to date indicate that flutamide is as effective as other conventional therapy. It has only moderate activity in patients in whom conventional hormonal therapy has previously failed, but appears to be beneficial when combined with an LHRH agonist.

Monotherapy with nilutamide, a pure nonsteroidal antiandrogen, in untreated patients with metastatic carcinoma of the prostate. The Italian Prostatic Cancer Project

A total of 26 previously untreated patients with metastatic carcinoma of the prostate received the pure nonsteroidal antiandrogen nilutamide as a single agent. Objective response rate was 38.5 +/- 18.7% (95% confidence interval). Median progression-free survival and median survival were 9 and 23 months, respectively. Of 13 patients with progression on antiandrogen 5 showed an additional objective response to a second-line endocrine treatment. The drug was generally well tolerated, except for 2 patients who discontinued treatment because of moderate gastrointestinal symptoms. Approximately a third of the patients complained of decreased adaptation to darkness. An electroretinogram and dark adaptation test revealed the presence of functional damage and visual complaints reversed in all patients on cessation of therapy. The other most frequent side effects were slight nausea (26.9% of the patients) and alcohol intolerance (19.2%). A nonsignificant increase in testosterone levels was shown within 1 month of treatment, after which the levels remained stable. Approximately half of the sexually active men claimed maintenance of libido and sexual potency during treatment. A slightly significant increase in hemoglobin was observed during the long term, suggesting the occurrence of a trophic effect by androgens on erythropoiesis. The results indicate that nilutamide as a single agent has an acceptable toxicity and a moderate activity, and may maintain sexual interest in a discrete number of cases. Whether monotherapy with nonsteroidal antiandrogens offers a valid option in the palliation of advanced disease remains to be seen in comparative prospective trials.

Carcinoma of the prostate. Guidelines for treatment: the role of antiandrogens

Our preliminary experience shows that flutamide is effective in patients with stage C or D prostate cancer. Local and distant response rates are comparable to those obtained with "classic" hormone therapy. Libido and sexual potency generally are unaffected. Palliation of symptoms, which is frequent, is usually accompanied by improved performance status and quality of life. Side effects are slight or moderate, but elevated transaminase levels in patients with borderline liver insufficiency are possible.

Flutamide: an antiandrogen for advanced prostate cancer

Flutamide is a nonsteroidal pure antiandrogen that acts by inhibiting the uptake and/or binding of dihydrotestosterone to the target cell receptor, thus interfering with androgen action. Flutamide is well absorbed orally and extensively metabolized; its active metabolite, 2-hydroxyflutamide, is formed rapidly and excreted almost entirely by the kidneys. Clinical studies in prostate cancer patients have demonstrated efficacy with flutamide monotherapy in patients who had received no prior treatment, in untreated patients with combined androgen blockade concomitantly with a luteinizing hormone-releasing hormone (LHRH)-agonist, and in relapsed patients. A randomized, placebo-controlled trial demonstrated a 26 percent increase in median survival for patients treated with leuprolide plus flutamide compared with leuprolide plus placebo. When given as monotherapy and in combination with an LHRH-agonist, flutamide is well tolerated. The usual adverse effects are gynecomastia and mild diarrhea when given as a single agent. In combination with an LHRH-agonist, hot flashes, loss of libido, impotence, mild nausea and vomiting, gynecomastia, and diarrhea are commonly reported. However, only diarrhea occurred more frequently in patients treated with leuprolide plus flutamide than in those treated with leuprolide plus placebo. Flutamide is indicated in combination with an LHRH-agonist (e.g., leuprolide) as initial therapy in metastatic (stage D2) prostate cancer. The usual dose is 250 mg po tid given at eight-hour intervals and started concurrently with the LHRH-agonist. Formulary addition is recommended.

Antiandrogens alone or in combination for treatment of prostate cancer: the European experience

In Europe, antiandrogens have been used for many years to treat prostate cancer, either as monotherapy or as part of a "combination therapy" with either surgical or chemical castration. However, considerable debate still exists regarding the relative benefits of combination therapy versus antiandrogen monotherapy or castration alone. This article reviews the European experience with antiandrogen therapy, including the personal experiences of the authors.

Long-term experience with flutamide in patients with prostatic carcinoma

Fifty-two patients with previously untreated metastatic carcinoma of the prostate were treated with flutamide 250 mg tid. Response was classified according to objective and subjective criteria, and duration of response and total survival were chosen as endpoints. Disease manifestations at presentation and tumor burden were studied to determine their relationship, if any, to treatment response and outcome. Total survival was longest in 26 patients who had objective responses (mean 50 months). Patients who failed to respond (n = 13) and those who had subjective responses (n = 13) survived an average of eleven and 17.2 months, respectively. Tumor burden was correlated with response to treatment and total survival; those judged to have a minimum tumor burden had objective responses and survived an average of sixty months. Sixteen other patients who had been previously treated with diethylstilbestrol were also studied. Nine of these had cardiovascular complications while taking diethylstilbestrol, and tolerated flutamide without further complications. Those in remission stayed in remission, and sexual potency returned to 5 patients.

Antiandrogen effects in models of androgen responsive cancer

The ability of antiandrogens to antagonize androgen effects in androgen responsive tissues is well established. Antiandrogens may diminish in vivo or in vitro proliferation of some androgen responsive cancer cells without causing cessation of multiplication. These model studies are representative of clinical experience in treatment of human prostate cancer with antiandrogen therapy. Recent studies in the AXC/SSh rat prostate cancer model show that these cancer cells elaborate polypeptide growth factors which stimulate their proliferation. If growth factor production by these cells is androgen independent, this may provide an explanation for failure of androgen ablation or antiandrogen treatment to effectively halt prostate cancer cell proliferation.

Hormonal changes induced by the pure antiandrogen flutamide in postmenopausal women with advanced breast cancer

Hormonal changes induced by the pure antiandrogen flutamide were studied in three postmenopausal metastatic breast cancer patients. The drug was administered at a dose of 250 mg, three times a day for 3-6 months. In each patient a sharp decrease of about 50% was observed in the circulating levels of DHT and DHEAS, irrespective of pretreatment values. A concomitant, although less pronounced, reduction in circulating testosterone, androstenedione and estradiol was found. A decrease in circulating steroids was associated with a 30% decrease in SHBG concentrations in two patients; in the third patient a 30% increase occurred. Androgens in urine, namely testosterone, androstanediol and 17-KS, decreased accordingly. In addition, a marked decrease in 17-OHCS occurred in two of the patients. These data indicate that flutamide is an effective antiandrogen in women and suggest two possible mechanisms by which the drug exerts its antiandrogenic activity: (a) inhibition of conversion of testosterone into the more active DHT, and (b) inhibition of synthesis of the adrenal precursors of active androgens. Minor variations in circulating LH and FSH were observed. Pretreatment prolactin values, which were higher than normal, dramatically decreased by 90% in one patient who had a partial remission of her disease, and they further increased in another patient who relapsed while on therapy.

Flutamide--an antiandrogen inhibiting prostatic cancer and prostatic secretion with retention of potency

Ten men with prostatic cancer, stage T3M0 Nx or more, who were anxious to maintain sexual potency, were treated with flutamide. The eight metastasis-free tumours remained stable during treatment periods of 3-48 months. The two tumours with metastasis at the start of treatment showed growth inhibition for 3 and 7 months, respectively, but thereafter progressed, leading to change of treatment. Nine of the ten men claimed maintained potency during flutamide therapy. Seven delivered ejaculate for biochemical analysis during or after flutamide therapy, as further evidence of potency. Biochemical analyses of the pre-flutamide ejaculates revealed higher values for markers of prostatic secretion in cases with high level of tumour differentiation. Significant reduction in the secreted amount of prostatic and seminal vesicle parameters was found in all the studied cases during flutamide therapy.

Short term effects of flutamide administration on hypothalamic-pituitary-testicular axis in man

The effect of short term administration of flutamide on the hypothalamic-pituitary-gonadal axis was studied in six patients with advanced prostate cancer (C2 stage). Flutamide significantly increased LH pulse frequency in all patients (p less than 0.05 by Wilcoxon's test). The FSH pulse analysis disclosed a similar pattern of LH. Plasma IC-T clearly increased following flutamide therapy; mean IC-T values were 2.67 +/- 0.47 ng./ml. and 4.67 +/- 0.62 ng./ml. before and after flutamide administration, respectively (p less than 0.05 by paired Student's t test). Our study demonstrates that flutamide acts in humans as a selective and specific antiandrogen compound.

The pharmacokinetics of flutamide and its major metabolites after a single oral dose and during chronic treatment

Flutamide is a nonsteroidal antiandrogen used in the treatment of prostatic carcinoma. We have investigated the disposition of flutamide and its two major metabolites in ten urological in-patients without significant liver or renal disease. After oral administration flutamide is absorbed from the gastrointestinal tract with a tmax of about 2 h. Flutamide undergoes extensive first-pass metabolism, and its major metabolites are 2-hydroxyflutamide and the hydrolysis product 3-trifluoromethyl-4-nitroaniline. After the oral administration of a single dose of 250 mg or 500 mg maximum flutamide plasma concentrations of 0.02 and 0.1 micrograms.ml-1 respectively were observed. Maximum plasma concentrations of 2-hydroxyflutamide for the same flutamide doses were 1.3 and 2.4 micrograms.ml-1 (mean of n = 2 or n = 3). Steady-state concentrations of the biologically active metabolite 2-hydroxyflutamide (0.94 +/- 0.23 micrograms.ml-1, mean +/- SD, n = 5) were found at 2-4 days after the administration of 250 mg every 8 h. The area under the plasma concentration time curve for 2-hydroxyflutamide averaged 11.4 (10.6 and 12.1) and 24.3 (21.5-29.4, n = 3) micrograms.ml-1.h for 250 mg and 500 mg flutamide orally. 2-Hydroxyflutamide and 3-trifluoromethyl-4-nitroaniline were eliminated monoexponentially with half-times of 4.3-21.9 and 4.3-17.2 h (n = 5) respectively.

Flutamide and other antiandrogens in the treatment of advanced prostatic carcinoma

The various clinical trials suggest that the qualitative and quantitative responses of patients with Stage D prostatic carcinoma to antiandrogens are similar to those achieved with conventional endocrine therapy. These antiandrogens appear generally safe and many avoid the increased risks of cardiovascular or thromboembolic complications seen with estrogen therapy. Further, flutamide appears to have a lesser adverse effect on libido and sexual potency than do alternative therapies. Antiandrogens offer an alternative mode of therapy for previously untreated patients with advanced prostatic cancer but have produced no convincing benefits in hormonally refractory patients.

Metabolism of steroid-modifying anticancer agents

The application of steroid-modifying drugs as a strategy for the treatment of hormone-dependent cancers has gained increasing popularity during the past decade. However, it is important to point out and emphasize that very few of the agents were originally designed for their current application. Most were designed for other purposes, predominantly fertility control (e.g. LHRH agonists and the antiestrogens). Nevertheless, now it is possible to integrate their actions to design rational therapies. There are many reasons for the current interest in antisteroidal drugs. The initial euphoria over the potential ability of combination chemotherapy to cure breast and prostatic carcinoma has proved to be premature. Combination chemotherapy has many severe side-effects which limits patient acceptability, especially if the patient realizes that the likelihood of a cure is remote. In the main, antisteroidal therapies do not have many side-effects and those that do, e.g. aminoglutethimide, are the focus of increased efforts in drug design to produce increased drug specificity. Finally, there is a growing realization that hormone-dependent cancer control with a nontoxic, antisteroidal therapy may be the most acceptable approach currently available for early disease management. Chemotherapy would then be reserved as the final option for treatment. The description of drug metabolism has been central to the development of synthetic LHRH analogs and an understanding of the mode of action of nonsteroidal antiestrogens and antiandrogens. The discovery of steroid synthetic pathways has been essential for the development of the aromatase inhibitors. This whole area of endeavor has now become a major focus of attention for the medicinal chemist. A new generation of agents is entering clinical evaluation which will provide a wealth of valuable information about the successful (or unsuccessful?) methods to control hormone-dependent disease. Since the success or failure of a drug can often depend upon formulation, pharmacokinetics, bioavailability or metabolism, it is our hope that this overview might help solve some of the future problems.

Combination therapy with flutamide and castration (LHRH agonist or orchiectomy) in previously untreated patients with clinical stage D2 prostate cancer: today's therapy of choice

One hundred and ninety-nine patients with clinical stage D2 prostate cancer who had not received previous endocrine therapy or chemotherapy were treated with the combination therapy using the pure antiandrogen Flutamide and the LHRH agonist [D-Trp6]LHRH ethylamide for an average of 26 months (3-59 months). The objective response to the treatment was assessed according to the criteria of the U.S. NPCP. There was a 5.7-fold increase (26.3 vs 4.6%) in the percentage of patients who achieved a complete response compared with the results obtained in five recent studies limited to removal (orchiectomy) or blockade (DES or Leuprolide) of testicular androgens. Only 12 of the 186 evaluable patients (6.5%) did not show an objective positive response at the start of the combination therapy compared with an average of 18% in the same five studies using monotherapy. The duration of response was also significantly improved in the patients who received the combination therapy while the death rate was decreased by approximately two-fold during the first 4 yr of treatment. In fact, while an approximately 50% death rate is observed at 2 yr in all studies using monotherapy, the same 50% death rate is delayed by 2 yr in the present study. It should be mentioned that at the time of relapse under combination therapy, the treatment is continued and, in addition, further blockade of adrenal androgen secretion is achieved with aminoglutethimide. The marked (5.7-fold) improvement in the rate of complete objective responses coupled with the three-fold decrease in the number of non-responders, the increased duration of the positive responses and the two-fold decrease in the death rate during the first 4 yr of treatment are obtained with the combination therapy using Flutamide and castration, thus improving the quality and duration of life with no or minimal side-effects. By blocking the androgen receptors in the prostatic cancer tissue, the antiandrogen decreases the action of the androgens of adrenal origin and thus inhibits the growth of a large number of tumors which, otherwise, would continue to be stimulated by the adrenal androgens left after medical or surgical castration.

The effect of androgen blockade on pulsatile gonadotrophin release and LH response to naloxone

In order to clarify the effects of androgen blockade on the hypothalamic-pituitary-testicular axis in man, four patients with advanced prostate cancer, not previously treated, were given oral flutamide, 250 mg three times daily for 9 days. Before, and 7, 8 and 9 days after starting flutamide treatment, on separate days, the following tests were performed: a gonadotrophin pulsatility study, with 20 min interval blood sampling for 12 h, a naloxone test and a GnRH test. Flutamide induced a significant increase in both LH and FSH pulse frequency, while pulse amplitudes and plasma integrated concentrations (IC) of LH and FSH were unaffected. Plasma integrated concentrations of testosterone and oestradiol rose significantly, while that of prolactin was unaffected. The increase in plasma LH concentration induced by naloxone injection was abolished by flutamide treatment. On the other hand, the small FSH response to naloxone was unaffected by flutamide treatment. Response to GnRH was unaffected by flutamide. These results suggest that flutamide exerts effective androgen blockade at the hypothalamic level, since, despite increased plasma testosterone concentrations, gonadotrophin pulse frequency increased and the LH response to naloxone was abolished.

Carcinoma of the prostate. Hormonal therapy

A selective review of the literature regarding hormonal therapy for patients with carcinoma of the prostate is presented to assess the current status of the following: therapeutic advantages, disadvantages and risks of alternate approaches to hormonal therapy; observations to predict the magnitude and duration of response to therapy; indications for initiating hormone therapy; the short-term and long-term effects of therapy; and role of hormone therapy in patients with recurrent tumor activity after initial hormonal measures.

Proliferation of AXC/SSh rat prostate cancer cells in vitro is androgen modulated

We used heterogeneous parental cultures of AXC/SSh rat prostate cancer cells to isolate clonally derived prostate cancer cell lines. Light and electron microscopic analyses established that parental and clonally isolated cells possess features characteristic of secretory epithelium. Biochemical analyses showed that these cells contained androgen receptors and acid phosphatase and 5 alpha-reductase activity; phenotypic markers characteristic of differentiated prostate epithelium. Content of these prostate epithelial cell markers was variable and cell line specific. We used selected cell lines to examine androgen modulation of AXC/SSh rat prostate cancer cell proliferation in vitro. We found that proliferation of C-family or D-family cells, those respectively maintained on medium without additions or medium containing 10(-7) M 5 alpha-dihydrotestosterone, was not affected by changes in medium testosterone concentration through the range 10(-6)-10(-9) M. In contrast, testosterone modified proliferation of T-family cells, those maintained on medium containing 10(-7) M testosterone, and effects were antagonized by the anti-androgen RU 23908. Preliminary studies established that AXC/SSh rat prostate cancer cells elaborate polypeptide components which stimulate in vitro cell proliferation. Both the ability to elaborate these components and their effects on in vitro cell proliferation appeared to be cell line specific.

Clinical evaluation of flutamide and estramustine as initial treatment of metastatic carcinoma of prostate

The efficacy and side effects of flutamide were compared with estramustine in patients with advanced prostatic carcinoma. Thirty patients with metastatic cancers but with no serious cardiovascular (CV) conditions were randomly assigned to receive treatment either with flutamide (250 mg X 3) or with estramustine (280 mg X 2). Clinical examination, bone scan, laboratory measurements, including coagulation studies were performed prior to randomization, every three months during year one, and at six-month intervals thereafter. The two groups were comparable with respect to age and tumor characteristics. However, more patients presented with skeletal pain among those later treated with flutamide. During an observation period of between one and two and one-half years, flutamide was discontinued in 1 case (7%) because of icterus, and estramustine in 3 cases (20%) because of CV complications. Of the remaining 14 flutamide-treated patients, 13 responded initially. Eleven of them relapsed, and 5 died of cancer. In the corresponding group of 12 estramustine-treated patients, there were 11 primary responders. Of these, only 2 relapsed and died as did the only nonresponder. The difference between the two groups with regard to relapse is significant (P less than 0.01), but not with regard to mortality. All estramustine-treated patients lost their libido, whereas only 20 per cent of the patients treated with flutamide did so. In the present limited material there was an initial favorable response to flutamide without signs of CV complications and with maintained libido in most cases. However, due to significantly increased risk for relapse compared with estramustine, flutamide cannot be recommended as single therapy except in cases where estrogens are contraindicated or when interference with libido and potency is unacceptable.

Treatment of prostatic cancer. Newer forms of androgen deprivation

The hope of providing a safe alternative to bilateral orchiectomy for patients with prostatic cancer has spurred the development in recent years of various agents capable of reducing androgen level. Another reason for intensifying these efforts relates to the hope held by many clinicians that earlier initiation of androgen deprivation for patients with regional or distant metastases will improve the patient's course. Finally, attempts to provide a more complete androgen blockade hold the hope of delaying or preventing relapse, which usually occurs with continued androgen deprivation.

Effects of different doses of cyproterone acetate (CA) on preputial gland structure and activity in intact male mice

The preputial is an androgen-dependent structure which appears to be used in pheromonal signalling in rats and mice. The structure of representative glands from intact oil injected male laboratory TO strain mice was contrasted with tissue from intact counterparts treated with the anti-androgen cyproterone acetate (CA). Sixteen days of an i.m. application of a modest range of CA doses (0.5, 1.0 and 2.0 mg/day given as oily solutions) and a variety of control treatments were used to assess influences on the structure and function of the preputial. The glands of intact male mice treated with oil were well-developed and actively secreting with parenchymatous acini at different stages of maturation. Such glands are generally highly Sudanophilic, with the lipophilic stain concentrated in acini in frozen sections and many acini are compressed by their neighbours to assume irregular shapes. Wax and frozen preputial sections from intact subjects treated with 0.5 or 1.0 mg CA were, in contrast, less well-developed and had fewer and smaller lipid droplets. Treatment of counterparts with 2 mg CA reduced acinar number and diameter in both wax and frozen sections with a concomitant increase in the proportion of connective tissue. The data confirm that this anti-androgen antagonizes the androgen secreted by the testis and adrenal cortex in terms of its expression of function on the preputial gland. These data provide further evidence that cyproterone acetate's suppressive actions on murine aggression are primarily via its ability to depress the secretion of odour cues that facilitate attack.

Hormone-independent polyamine metabolism of squamous cell carcinoma of the prostate

The levels of polyamines and their synthesizing enzymes in squamous cell carcinoma of prostate implanted in intact as well as castrated male rats were determined after certain hormonal manipulations. The tumour was found to grow with an identical rate in non-castrated and castrated rats. Polyamine content and activities of polyamine synthesizing enzymes in the tumour were found to be much lower compared to their values in ventral prostate. Moreover, the levels of these parameters were comparable in tumours whether implanted in non-castrated or gonadectomized animals. The sequential analyses of putrescine and spermidine and activities of L-ornithine decarboxylase and S-adenosyl-L-methionine decarboxylase of tumours at different time intervals showed a significant reduction in their levels at 30 days compared to 10 days post implantation in non-castrated as well as castrated rats. Daily intramuscular administration of tumour-bearing intact or castrated animals with testosterone (50 micrograms/g), beta-estradiol (2 micrograms/g) or cyproterone (12.5 micrograms/g) for 10 days did not influence polyamine metabolism in tumour tissue. However, either beta-estradiol and cyproterone treatments or castration were found to decrease polyamine synthesis in ventral prostate. At the same time, the testosterone replacement therapy did not allow polyamine levels or activities of polyamine synthesizing enzymes to decline in the ventral prostate of castrated rats. Our results demonstrated that contrary to ventral prostate, the polyamine metabolism in squamous cell carcinoma of prostate is independent of hormonal control. The loss of hormonal sensitivity of polyamine metabolism in the prostatic tumour could be the result of qualitative changes that occurred during transformation.

Experience with flutamide in patients with advanced prostatic cancer without prior endocrine therapy

Seventy-two patients with advanced prostatic carcinoma without previous endocrine therapy were treated with an oral nonsteroidal antiandrogen, flutamide. Sixty-three patients (87.5%) had a favorable response, and 9 patients showed no response. Flutamide appears to be a safe antiandrogen, usually effective in the management of patients with advanced prostatic cancer who have had no prior endocrine therapy.

New hormonal treatment in cancer of the prostate: combined administration of an LHRH agonist and an antiandrogen

At doses which have no or minimal inhibitory effect when administered alone, the LHRH agonist [D-Ser(TBU)6,des-Gly-NH10(2)] LHRH ethylamide (HOE-766) and the antiandrogen RU-23908 administered simultaneously cause a marked inhibition of ventral prostate and seminal vesicle weight after 5 months of treatment. The effect of the LHRH agonist is due to a blockage of the testicular steroidogenic pathway. The same LHRH agonist administered to adult men with cancer of the prostate causes a marked inhibition of serum testosterone and dihydrotestosterone to castration levels within 1-2 weeks. Administration of the pure antiandrogen to men with cancer of the prostate already receiving the LHRH agonist does not interfere with the LHRH agonist-induced blockage of androgen biosynthesis: Moreover, objective signs of remission of the disease were rapidly observed in 8 out of 10 patients. The ease of application of this new form of hormonal therapy which neutralizes androgens from all sources should facilitate its early administration and thus minimize the development of metastases and androgen-resistant cell clones.

Human prostatic adenocarcinoma: comparative experimental treatment of the tumor line PC 82 in nude mice

A human prostatic adenocarcinoma, growing as a transplantable line in nude mice, was subjected comparatively to the usual endocrine treatment schedules including orchiectomy, estrogens, estramustine phosphate, and a study with flutamide (SCH 13521) and cyproterone acetate. The regression under treatment in tumor volume and in the histological pattern in demonstrated, and the possibilities and limitations of the nude mouse model are discussed.

Combined long-term treatment with an LHRH agonist and a pure antiandrogen blocks androgenic influence in the rat

Daily administration for 5 months of the potent LHRH agonist (D-Ser(TBU)6, des-Gly-NH2(10)) LHRH ethylamide (250 ng) in combination with the pure antiandrogen RU23908 (5 mg) to adult male rats causes a marked inhibition of ventral prostate and seminal vesicle weight to 9% and 15% of control, respectively. At the doses used, owing to readjustments of the pituitary-testicular axis, neither treatment alone has an effect on prostate weight and exerts only minimal inhibitory effects on seminal vesicle weight. Whereas treatment with the LHRH agonist alone markedly inhibits testicular LH and PRL receptor levels, the antiandrogen alone stimulates the concentration of the two receptors and reverses the inhibitory effect of the LHRH agonist treatment on LH receptors. Treatment with the LHRH agonist decreases plasma PRL levels, whereas the antiandrogen increases the concentration of circulating LH and FSH by 250%. Treatment with the LHRH agonist decreases the concentration of testosterone and its precursors of the delta 4-pathway while stimulating 5 alpha-reductase activity in both the absence and presence of simultaneous treatment with the antiandrogen. The present data show that blockage of the delta 4-steroidogenic pathway induced by treatment with an LHRH agonist prevents the escape phenomenon observed during long-term treatment with a pure antiandrogen, and permits maximal inhibitory effects of the two treatments on secondary sex organ weight. Such combined treatment with an LHRH agonist (to block androgen formation) and an antiandrogen (to neutralize remaining androgens of testicular and adrenal origin) should be the hormonal therapy of choice in prostatic carcinoma.

Inhibition of androgen binding in human foreskin fibroblasts by antiandrogens

Antiandrogen effects on androgen receptor binding and androgen metabolism were studied in cultured human newborn foreskin fibroblasts. Three different antiandrogens were tested in this system: (a) cyproterone acetate (CA); (b) RU23908; and (c) R2956. CA and R2956 were equipotent inhibitors of androgen binding to its intracellular receptor. The magnitude of this action was nearly twice as great against the endogenous androgen ligands, dihydrotestosterone (DHT) or testosterone (T), than with the synthetic ligand, methyltrienolone (R1881). Whereas the relative binding affinities of CA and R2956 were approximately 5-10 times less than T or DHT, RU23908 was another order of magnitude less effective as an inhibitor of androgen binding. The lower relative binding affinity determined for RU23908 could not be explained on the basis of a requirement for metabolic activation. Subcellular fractionation studies and sucrose density gradient analysis further confirmed the rank order of antiandrogenic potency. None of the antiandrogens influenced the rate or profile of metabolites from cellular metabolism of T or DHT. We propose that cultured human genital skin fibroblasts may serve as a valuable system for the future evaluation of antiandrogens in intact ells under physiologic conditions.

Flutamide in the treatment of metastatic carcinoma of the prostate

Twenty-five patients with metastatic carcinoma of the prostate were treated with Flutamide, a non-steroidal anti-androgen. All patients showed progression; the longest response was 120 weeks. The side effects were nausea, vomiting, breast tenderness and gynaecomastia.

Additive inhibitory effects of treatment with an LHRH agonist and an antiandrogen on androgen-dependent tissues in the rat

Combined treatment of adult male rats with the LHRH agonist, [D-Ser(TBU)6, des-Gly-NH2(10)]LHRH ethylamide, and a non-steroid antiandrogen, RU 23908, led to a rapid and marked atrophy of the ventral prostate and seminal vesicles. Treatment with the LHRH agonist decreased androgen secretion and thus facilitated the action of the antiandrogen in androgen-dependent tissues. Such a combined treatment could be useful in the treatment of androgen-dependent pathologies in man, particularly in prostatic adenocarcinoma and possibly benign prostatic hyperplasia.

Experience with flutamide in previously untreated patients with advanced prostatic cancer

Twenty-one patients with advanced prostatic adenocarcinoma previously untreated with conventional endocrine therapy were treated with an oral non-steroidal antiandrogen, flutamide. There were 19 favorable responders, 1 failure and 1 equivocal response. Flutamide seems to be a safe antiandrogen, which is effective in the management of previously untreated patients with advanced prostatic carcinoma.

Altered androgen metabolism in metastatic prostate cancer

Admixture of androgen-sensitive elements from normal or hyperplastic prostatic tissue interferes with biochemical studies of prostate cancer in its primary site. Heterogeneity of cancer tissues, varying in stromal and epithelial elements, also complicates interpretation of data relating to androgen metabolism. Accordingly, we have compared metastatic deposits composed of epithelial cancer cells to the primary biopsies of 4 patients in respect to uptake of 3H-testosterone and its conversion to 5-alpha-dihydrotestosterone during in vitro incubation. 3H-testosterone uptake was similar for both tissue sites but 3H-dihydrotestosterone formation was reduced by 76% in the metastases compared to primary tissues. This group was not large enough to show statistical significance, whereas a total of 11 such primary studies compared to 6 metastatic specimens was significant. When either primary or secondary tissue results were compared to 12 cases of benign prostatic hyperplasia similarly studied the differences were highly significant. These results demonstrate a major impairment in the formation of dihydrotestosterone by metastatic prostatic cancer and a similar but less evident alteration in the primary site. This abnormality in testosterone metabolism is of major importance in the attempt to obtain effective hormonal control of human prostatic cancer.

In vitro uptake of 3H testosterone and its conversion to dihydrotestosterone by prostatic carcinoma and other tissues

Needle biopsies of normal, benign hyperplastic, neoplastic and metastatic prostatic tissues were used to study the uptake of 3H testosterone by these tissues and their ability to convert testosterone to dihydrotestosterone. Histological quantification is important because stroma is active in both of these areas of biochemical activity. The 3H testosterone uptake by the tissues is relatively similar but benign prostatic hyperplasia and normal tissue consistently convert more testosterone to dihydrotestosterone than do neoplastic tissues. The least active in this regard are pure biopsies of neoplastic cells obtained from nodal metastases, suggesting extensive loss or repression of 5-alpha-reductase activity. Further, this defect is present in neoplastic tissues even if the patient has had an orchiectomy and/or received hormonal therapy. It is not known whether testosterone may substitute for dihydrotestosterone in the neoplastic nucleus. Our studies indicate that animal models that yield data on suppresion of 5-alpha-reductase activity by certain agents may have limited relevance to the tissues of human prostatic carcinoma.

Comparison of flutamide (SCH-13521) and diethylstilbestrol in untreated advanced prostatic cancer

A double-blind study comparing the efficacy of flutamide (SH-13521) and diethylstilbestrol in 15 patients with advanced, previously untreated adenocarcinoma in the prostate in herein presented. Patients receiving diethylstilbestrol, 1 mg. daily, remained stable without evidence of progression of their disease for an average of 25.6 weeks while those receiving either high-or low-dose flutamide showed no objective progression for an average of thirty weeks. There were no complete remissions, and no signficant side effects were seen with either of these agents. In this small series of hormonally untreated Stage D prostatic cancer patients, neither agent displayed significant superiority.