Stilbestrol Diphosphate on Serum Hormonal Levels in Patients with Hormone-Refractory Prostate Cancer

Endocrine Journal 1999, 46 (5), 659-664

Effects of Intravenous Administration of High Dose-Diethyl- stilbestrol Diphosphate on Serum Hormonal Levels in Patients with Hormone-Refractory Prostate Cancer

SATOSHI KITAHARA, HIROSHI UMEDA, MASATAKA YANO, FUMITAKA KOLA, SHUHEI SUMI, HIDEO MORIGUCHI, YOSHIKATSU HOSOYA, MIKIHIKO HONDA AND KENICHIRO YOSHIDA

Department of Urology, Dokkyo University School of Medicine, Mibu, Tochigi 321-02, Japan

Abstaract. The objective of this study was to elucidate the mechanism underlying the further suppression of serum testosterone (T) by diethylstilbestrol diphosphate (DES-DP) in patients with prostate cancer refractory to hormonal treatment. These patients received an LHRH agonist with or without a non-steroidal androgen-receptor blocker or a gestagen before DES-DP. We measured serum levels of total and free T, dihydrotestosterone (DHT), estradiol (E2), dehydroepiandrosterone sulfate (DHEA-S), dehydroepiandrosterone (DHEA), androstenedione, cortisol, aldosterone before and during intravenous administration of high doses of DES-DP (500 or 1000 mg/day). DES-DP administration suppressed the serum levels of FSH (p=0.04) and total T (p=0.02), and eliminated free T (p =0.04) and E2 (p = 0.04) from serum, while reducing serum DHEA-S to approximately two-thirds of the pretreatment level (p=0.03). In contrast, serum levels of SHBG (p=0.02) and cortisol (p=0.02) were markedly increased after DES-DP administration. The latter had no significant effect on serum levels of LH, DHT, ACTH, 17a-hydroxypregnenolone, 17a-hydroxyprogesterone, DHEA, androstenedione, or aldosterone. The results suggest that the potent suppression of circulating total T by DES-DP is caused, in part, by the inhibitory effect of DES-DP on serum DHEA-S level. In most patients, high-dose DES-DP treatment completely suppressed the serum level of free T, while possibly elevating serum SHBG and decreasing serum total T. The mechanisms that maintain the serum level of serum DHT during DES-DP treatment require further elucidation.

Key words: Prostate cancer, DES-DP, Testosterone, Dihydrotestosterone, DHEA-S, SHBG (Endocrine Journal 46: 659-664, 1999)

APPROXIMATELY one-third of the patients with The administration of synthetic estrogens may be prostate cancer have clinical metastases when initially of benefit in patients with hormone-refractory diagnosed. Patients with advanced prostate cancer prostate cancer, although the duration and the first undergo medical or surgical castration in order benefit are limited [4, 5]. The mechanisms for these to reduce the serum levels of testosterone (T). Most beneficial effects were not known until recently, of these patients show some improvement after when a direct cytotoxic effect of diethylstilbestrol testicular androgen ablation [1] . However, almost diphosphate (DES-DP) on prostate cancer cells was all patients with an initially good response to such reported in vitro [6]. We previously showed that a therapy relapse and die within a few years [2]. therapeutic per os dose of DES-DP, a synthetic Their condition is termed hormone-refractory [3]. estrogen, suppresses serum total T to undetectable levels. The effect is significantly stronger than that of surgical castration or of the administration Received: January 5, 1999 of an LH-RH agonist [7]. We presume a potent Accepted: May 24, 1999 suppressive effect on serum T might be one of the Correspondence to: Dr. Satoshi KITAHARA, Department of mechanisms of DES-DP action in patients with Urology, Koshigaya Hospital, Dokkyo University School of Medicine, 2-1-50, Minami-Koshigaya, Koshigaya, Saitama hormone- refractory prostate cancers. Such cancer 343-8555, Japan is able to proliferate even at a level of serum T fol- 660 KITAHARA et al.

lowing induction of castration, approximately 5% of The patients were weighed daily. Blood samples serum T level before castration. were collected at 0600-0800 h on day 1 to 2 wk before Adrenal androgens are thought to be the source of the beginning of treatment and again on the last day serum T following surgical or medical castration. of the treatment, with the patient's informed consent. We hypothesized that DES-DP might affect the pathway of steroid biosynthesis or its metabolism. Hormone assays Accordingly, in the present study, we measured serum levels of several hormones including adrenal Serum and plasma prepared from blood samples steroids and sex hormone-binding globulin (SHBG) were stored frozen at -80°C until assayed. All in patients with hormone refractory prostate cancer, circulating hormones in serum were measured by before and during the intravenous administration of radioimmunoassay in this study; i.e., ACTH, LH, large doses of DES-DP in an effort to elucidate the FSH, aldosterone, androstenedione, cortisol, 17a- mechanism of suppression of serum T by DES-DP. hydroxypregnenolone, 17a-hydroxyprogesterone, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), free and total Subjects and Methods testosterone (T), and estradiol (E2). Sex hormone- binding globulin (SHBG) was measured by an im- Patient characteristics munoradiometric assay. The intraassay CV varied from 2.5% in LH to 17% for 17a-hydroxyprogester- Profiles of our seven patients are shown in Table 1. one, while the interassay CV varied from 2.1% in LH These Japanese men, aged 53 to 93 years, had been to 20% for 17a-hydroxyprogesterone. diagnosed as having advanced prostate cancer with bone metastasis and had been treated with an LH-RH Statistical analysis agonist, gosereline acetate (Zeneca Japan Phar- maceutical Co. Ltd., Tokyo) or leuprorelin acetate Data are expressed as mean±SD. The effects of (Takeda Pharmaceutical Co. Ltd., Osaka), with or DES-DP were confirmed by the Wilcoxon signed- without an anti-androgen (chlormadinone acetate, a rank (paired) test using Stat View (statistics software synthetic progesterone; Teikoku Hormone Mfg. Co., from Abacus Concepts, Inc., Berkeley, CA). For Ltd., Tokyo) or hydroxyflutamide, a non-steroidal convenience in statistical analysis, an undetectable androgen blocker (Nikon Kayaku Co. Ltd., Tokyo). level was considered to be the lower limit of detec- These patients had initially shown an improvement tion. A level of p <0.05 was accepted as statistically on such treatment but had relapsed 4 to 24 months significant. later. The relapse was confirmed by determination of serum levels of prostatic acid-phosphatase (PAP) or prostatic specific antigen (PSA), computerized Results tomography (CT) scans, and bone scintigraphy. Most patients were experiencing bone pain related Edema caused one patient to discontinue the to progressive bone metastases. treatment on the 14th day, and two patients deve- loped loss of appetite, but were able to continue Clinical protocol therapy (Table 1). In the 7 patients in whom the data were evaluative, no significant difference was ob- Each patient received DES-DP (Honvan: Kyorin served in circulating levels of the hormones and Pharmaceutical Co. Ltd., Tokyo) at a daily dose of SHBG measured for the three androgen-deprivation 1000 mg, sometimes reduced to 500 mg, based on therapy, that is, an LHRH agonist, an LHRH body weight and cardiovascular status. DES-DP, agonist with chlormadinone acetate, or an LHRH 250 mg or 500 mg, was freshly diluted in 250 mL of agonist with hydroxyflutamide (Tables 1-5). There- 5% dextrose and infused for 3 hours twice daily. A fore, all three androgen ablation therapies were con- dose of 81 mg acetylsalicylic acid was given orally sidered to exert similar effects on the hormonal everyday during the treatment to prevent thrombosis. milieu. SERUM HORMONAL CHANGES BY DES-DP 661

Table 1. Characteristics of patients with hormone-refractory prostate cancer who received high-dose intravenous diethylstilbestrol diphosphate

Table 2. Serum levels of hormones and SHBG before and during diethylstilbestrol diphosphate treatment in patients with hormone-refractory prostate cancer

Table 3. Serum levels of pituitary hormones before and during diethylstilbestrol diphosphate treatment in the patients with hormone-refractory prostate cancer 662 KITAHARA et al.

Table 4. Serum levels of steroids before and during diethylstilbestrol diphosphate treatment in patients with hormone-refractory prostate cancer

Table 5. Serum levels of adrenal androgens before and during diethylstilbestrol diphosphate treatment in patients with hormone-refractory prostate cancer

With high dose DES-DP, serum free and total T with previous androgen ablation therapies (Tables 4, (free: p = 0.042, total: p = 0.018) and E2 (p = 0.043) 5). Serum levels of 17a-hydroxyprognenolone, 17a- decreased and serum SHBG (p = 0.0l 8) increased hydroxyprogesterone, DHEA, androstenedione and significantly compared with previous treatments aldosterone appeared to be unaffected by DES-DP (Table 2). Serum free T was not detected except for treatment (Table 4, 5). one patient with DES-DP treatment, while no significant change in serum DHT levels was observed with DES-DP treatment (Table 2). Discussion For pituitary hormones, serum FSH decreased significantly (p = 0.042) and both LH and ACTH The endocrine effect of exogenous estrogens on showed no change during DES-DP administration serum T is thought to be due to suppression of the (Table 3). serum level of LH, i.e., acting via a negative feedback For serum steroids which are thought to be mainly mechanism [8, 9] . As we observed in the present from the adrenal, DES-DP treatment increased cor- study and have previously reported, not only an tisol (p = 0.018) and decreased DHEA-S (p = 0.034) LH-RH agonist but also therapeutic doses of DES- approximately one third significantly in comparison DP reduce the serum level LH to an undetectable SERUM HORMONAL CHANGES BY DES-DP 663

level, although serum levels of T are suppressed more via androstenediol might have been activated by the strongly by DES-DP than by an LH-RH agonist or administration of DES-DP. The existence of a by bilateral orchiectomy or by combined androgen similar phenomenon has been confirmed in the blockade with an LH-RH agonist and an androgen prostate following castration [8, 14, 15]. receptor blocker [7]. The detectable T in serum of We assume that the maximal ablation of serum free the patients treated by an LH-RH agonist, with or T by the administration of high dose DES-DP has without one of the anti-androgens, or surgical cas- some advantage in treating patients with hormone tration must originate from serum adrenal andro- refractory prostate cancer, considering the beneficial gens. effect to the patients who suffer a relapse after an- The serum level of DHEA-S, a representative cir- drogen ablation treatment and evidence of am- culating adrenal androgen, was decreased to approx- plification of androgen receptor genes in hormone- imately two-thirds of the pretreatment level following refractory prostate cancer cells [16, 17]. That is, the the administration of DES-DP. In contrast, the level condition of the disease, at least in some cases, after of serum cortisol was significantly increased, but that androgen-deprivation therapy is not completely hor- of other adrenal steroids was not. Although an ele- mone-independent but remains endocrine-sensitive, vation of serum ACTH by estrogen has been reported probably androgen-hypersensitive. by some investigators [10], the level of ACTH in the Clinical reports on ketoconazole, a P450 inhibitor, elderly patients in the present study administered and/or glucocorticoid therapy administered for hor- anti-androgen therapy was not affected by DES-DP. mone refractory prostate cancer [18, 19] and in vitro These observations suggest that DES-DP blocks studies of mutant androgen receptor in prostate can- some pathway of steroid synthesis or metabolism in cer cells [20] support the progressive effect of adrenal these patients. We infer that only DHEA-S, among androgens on prostate cancer, especially those that the adrenal androgens measured in the present study, are hormone-refractory. While the administration is affected by DES-DP, because most of the adrenal of high doses of DES-DP decreases serum T from androgens are secreted as DHEA-S. One possible castration level to undetectable ones in patients mechanism of the effect on serum DHEA-S is the receiving androgen ablation therapy, the reduction in inhibition of C17_20lyase activity by DES-DP, which serum DHEA-S produced by high doses of DES-DP could increase the cortisol level and decrease the level was only one-third of the serum levels by androgen of adrenal androgens. The same effect of estrogen ablation therapy. These results suggest that a was reported in the murine testis in vitro [11, 12]. combination therapy of estrogen, glucocorticoid However, an increased clearance of adrenal steroids and ketoconazole may be more beneficial to some resulting from a decrease in serum albumin and an patients with hormone-refractory prostate cancer effect on liver function have been also postulated as than an estrogen therapy when the adverse effects the main cause of the suppression of serum DHEA-S are mild. by exogenous estrogens [9, 13]. We conjecture that In conclusion, the potent suppression of circula- a bioconversion from adrenal androgens and ting T by high doses of DES-DP appears to result, at testosterone involving activity of 3 j3-hydroxysteroid least in part, from suppression of serum levels of dehydrogenase or 17p-hydroxysteroid dehydrogenase DHEA-S, a representative adrenal androgen, by at peripheral sites is also being influenced by DES-DP DES-DP. The suppression of serum adrenal andro- [8]. gens and the increase in serum SHBG appeared to The almost complete ablation of serum free T by produce a maximal decline in serum free T. The DES-DP administration appears to result from both mechanism responsible for the unchanged levels of increase of serum SHBG and a strong suppression of DHT after the administration of DES-DP requires serum T. On the other hand, the fact that serum further study. DHT did not show a decrease following the administration of DES-EP, even though serum levels of T, E2 and DHEA-S were all decreased by DES-DP, is Acknowledgment hard to explain from the present data. We speculate that bioconversion from adrenal androgens to DHT We are indebted to Mrs. Kyoko Arai for her 664 KITAHARA et al.

technical assistance and, to Dr. Toshikazu Imai for assistance with the patients.

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