Treatment of advanced refractory ovarian carcinoma with a gonadotropin-releasing hormone analogue

Hormone therapy for ovarian cancer: Emphasis on mechanisms and applications (Review)

Ovarian cancer (OC) remains the leading cause of mortality due to gynecological malignancies. Epidemiological studies have demonstrated that steroid hormones released from the hypothalamic-pituitary-ovarian axis can play a role in stimulating or inhibiting OC progression, with gonadotropins, estrogens and androgens promoting OC progression, while gonadotropin-releasing hormone (GnRH) and progesterone may be protective factors in OC. Experimental studies have indicated that hormone receptors are expressed in OC cells and mediate the growth stimulatory or growth inhibitory effects of hormones on these cells. Hormone therapy agents have been evaluated in a number of clinical trials. The majority of these trials were conducted in patients with relapsed or refractory OC with average efficacy and limited side-effects. A better understanding of the mechanisms through which hormones affect cell growth may improve the efficacy of hormone therapy. In the present review article, the role of hormones (GnRH, gonadotropins, androgens, estrogens and progestins) and their receptors in OC tumorigenesis, and hormonal therapy in OC treatment is discussed and summarized.

Role of Gonadotropin-Releasing Hormone (GnRH) in Ovarian Cancer

The hypothalamus–pituitary–gonadal (HPG) axis is the endocrine regulation system that controls the woman’s cycle. The gonadotropin-releasing hormone (GnRH) plays the central role. In addition to the gonadotrophic cells of the pituitary, GnRH receptors are expressed in other reproductive organs, such as the ovary and in tumors originating from the ovary. In ovarian cancer, GnRH is involved in the regulation of proliferation and metastasis. The effects on ovarian tumors can be indirect or direct. GnRH acts indirectly via the HPG axis and directly via GnRH receptors on the surface of ovarian cancer cells. In this systematic review, we will give an overview of the role of GnRH in ovarian cancer development, progression and therapy.

Current management strategies for ovarian cancer

Epithelial ovarian cancer originates in the layer of cells that covers the surface of the ovaries. The disease spreads readily throughout the peritoneal cavity and to the lymphatics, often before causing symptoms. Of the cancers unique to women, ovarian cancer has the highest mortality rate. Most women are diagnosed as having advanced stage disease, and efforts to develop new screening approaches for ovarian cancer are a high priority. Optimal treatment of ovarian cancer begins with optimal cytoreductive surgery followed by combination chemotherapy. Ovarian cancer, even in advanced stages, is sensitive to a variety of chemotherapeutics. Although improved chemotherapy has increased 5-year survival rates, overall survival gains have been limited because of our inability to eradicate all disease. Technologic advances that allow us to examine the molecular machinery that drives ovarian cancer cells have helped to identify numerous therapeutic targets within these cells. In this review, we provide an overview of ovarian cancer with particular emphasis on recent advances in operative management and systemic therapies.

Second-line therapy of advanced ovarian cancer with GnRH analogs

Ovarian cancer is still the first cause of death among female malignancies. The standard treatment adopted in ovarian cancer is a radical surgical treatment or cytoreduction, followed by six courses of platinum-based chemotherapy; second-line regimens are associated with severe side effects. GnRH analogs could represent an alternative therapeutical approach. The aim of our study was to evaluate the role of GnRH analogs in the management of platinum-resistant ovarian cancers. We enrolled 12 patients affected by advanced ovarian cancer, previously treated with six courses of platinum-paclitaxel. In second-line therapy, we used leuprolide on 1, 8, and 28 days of treatment. CA 125 levels were recorded for each patient. One case of clinical partial response was obtained (8.3%). Stable disease was diagnosed in three patients (25%). Progression was recorded in eight cases (66.7%). Progression-free survival was 6 months. The treatment was well tolerated by patients. The high tolerability and the results obtained with leuprolide versus platinum in second-line therapy might permit a better use of the analogs for advanced ovarian cancer.

No rules without exception: long-term complete remission observed in a study using a LH-RH agonist in platinum-refractory ovarian cancer

OBJECTIVE

Second-line chemotherapy in platinum/paclitaxel-resistant ovarian cancer induces an objective response in <15% and third-line chemotherapy results in responses less than 10%. Chemotherapy always results in side effects with the risk of a low quality of life. Endocrine therapy is used world-wide among chemo-resistant ovarian cancer. Tamoxifen is a standard palliative treatment in many centers. LH-RH (luteinizing hormone-releasing hormone) agonists have also demonstrated activity among patients with ovarian cancer in several studies with response rates of 9-12% and disease stabilization in 15-26% of these women.

METHODS

In this retrospective study 32 patients with ovarian cancer who had relapsed after platinum/paclitaxel-based first-line chemotherapy and had exhausted all standard treatments received LH-RH analogue Leuprorelin depot 3.75 mg sc once a month until tumor progression.

RESULTS

One patient (3%) had a complete response, with remission time over 3 years. Two patients (6%) reached partial response with remission time of 3 and 4 months. Four patients (12%) remained stable for a mean time of 7 months (range 4-12 months). The remaining 25 patients (78%) had progressive disease. The treatment was well tolerated, and no major toxicity has been reported.

CONCLUSION

This study showed that LH-RH agonist Leuprorelin has only a limited effect in patients pretreated with platinum-based chemotherapy.

Chemotherapy versus hormonal treatment in platinum- and paclitaxel-refractory ovarian cancer: a randomised trial of the German Arbeitsgemeinschaft Gynaekologische Onkologie (AGO) Study Group Ovarian Cancer

BACKGROUND

The majority of patients with ovarian cancer are not cured by first-line treatment. Until now, no study could demonstrate any substantial benefit when exposing ovarian cancer patients to second-line chemotherapy. However, most treatment regimens induce toxicity, thus negatively influencing the quality of rather limited life spans. Here we evaluate whether a second-line chemotherapy can offer any benefit compared with a less toxic hormonal treatment.

PATIENTS AND METHODS

Patients with ovarian cancer progressing during platinum-paclitaxel containing first-line therapy or experiencing relapse within 6 months were eligible. Patients were stratified for response to primary treatment (progression versus no change/response), and measurable versus non-measurable disease. Treatment consisted of either treosulfan 7 g/m5 infused over 30 min or leuprorelin 3.75 mg injected subcutaneously or intramuscularly. Both regimens were repeated every 4 weeks.

RESULTS

This study began in late 1996, and after 2.5 years accrual an interim analysis was performed when several investigators reported their concern about a suspected lack of efficacy. Following this analysis the recruitment was stopped early and the 78 patients already enrolled were followed up. The majority of patients received treatment until progressive disease was diagnosed or death occurred. Treatment delay was observed rarely and dose reduction was performed only in the treosulfan arm in 5% of 150 courses. Overall, both treatment arms were well tolerated. No objective responses were observed. The median survival time was 36 and 30 weeks in the treosulfan and leuprorelin arms, respectively. Overall survival did not differ between patients with relapse 3-6 months after first-line chemotherapy compared with patients with progressive disease within 3 months.

CONCLUSIONS

The selected patient population represents a subgroup with extremely poor prognosis. Accordingly, results were not impressive. Both treatment arms showed favourable toxicity data, but failed to show remarkable activity, thus adding only limited evidence to the issue of whether patients with refractory ovarian cancer might benefit from second-line chemotherapy. Even stratified analysis did not identify any subgroup of patients in whom the administration of second-line chemotherapy could demonstrate a clinically relevant survival benefit.

Inhibition of in situ expression of aromatase P450 in leiomyoma of the uterus by leuprorelin acetate

We have shown that in situ estrogen synthesized in leiomyoma of the uterus plays a possible role in the promotion of leiomyoma cell growth via an autocrine/paracrine mechanism. In the present study, we demonstrated that leuprorelin acetate, a GnRH agonist widely used for treatment of uterine leiomyoma by down-regulation of pituitary-ovarian function, suppressed the expression of aromatase P450 (an estrogen synthetase) in leiomyoma cells. Given the role of in situ estrogen in leiomyoma cell growth, the inhibition of in situ estrogen synthesis may play a role in GnRH agonist-induced rapid regression of leiomyomas. Quantitative RT-PCR revealed that in women receiving no medication uterine leiomyomas express aromatase P450 mRNA at levels 20 times higher than that in the surrounding myometrium. Leuprorelin acetate treatment (1.88 mg every 4 wk, sc injection) for 12-24 wk reduced the expression of aromatase P450 mRNA in leiomyoma tissue as well as in the myometrium, to approximately one tenth of that in the myometrium of untreated women. Suppression of aromatase P450 expression was also demonstrated by Western blot analysis and aromatase activity assay of microsomal fractions prepared from leiomyomas. On the other hand, no differences in the levels of activity and mRNA of aromatase P450 were observed between leiomyoma cells obtained from women treated with and without leuprorelin acetate injections when cells were cultured ex vivo and stimulated by various combinations of stimulants such as dexamethasone + IL-1beta. The addition of various concentrations of E2 did not affect the aromatase activity of leiomyoma cells, suggesting that deprivation of circulating (ovarian) estrogen is not a cause of decreased expression of aromatase during leuprorelin acetate therapy. On the other hand, 8-d treatment with leuprorelin acetate (100 nmol/liter) reduced dexamethasone + IL-1beta-induced activity and a mRNA level of aromatase by 28% and 42%, respectively. These results indicated that leuprorelin acetate inhibits the expression of aromatase P450 in leiomyoma cells, which contributes to the rapid regression of leiomyoma during leuprorelin acetate therapy.

D-TRP-6-LHRH (Triptorelin) is not effective in ovarian carcinoma: an EORTC Gynaecological Cancer Co-operative Group Study

Between March and September 1988, 74 patients with progressive ovarian cancer after prior platinum-based therapy were treated with the luteinizing hormone-releasing hormone (LHRH) agonist Triptorelin (Decapeptyl degrees). Treatment consisted of i.m. injection of 3.75 mg of microencapsulated Triptorelin on days 1, 8 and 28 followed by 4-weekly injections until tumor progression. No objective responses were observed. Eleven out of 68 evaluable patients (16%) had stable disease. The median progression-free survival was 5 months in patients with disease stabilization and 2 months for all evaluable patients. The median survival for patients with disease stabilization was 17 months, whereas for all patients it was 4 months. The treatment was well tolerated; the only reported adverse events were incidental hot flushes. This study showed that the LHRH agonist Triptorelin has only modest efficacy in patients pretreated with platinum-containing chemotherapy.

GnRH receptor and apoptotic signaling

In addition to its hypophysiotropic action, gonadotropin-releasing hormone (GnRH) can modify activity in extrapituitary organs and peripheral tumors. GnRH analogs are the preferred treatment for advanced and even metastatic or recurring carcinomas in vivo and in vitro. Hormone-responsive tumors undergo apoptosis with the appropriate stimulus; GnRH-induced tumor growth arrest may result from stimulated apoptotic cell death. The sensitivity of tumors and normal tissue to GnRH is strongly associated with the possession of receptors for GnRH as well as other hormonal control. Despite the lack of a precise apoptotic signaling cascade through GnRH receptors, biochemical events observed within a plasma membrane appear to constitute the most convincing evidence that the membrane event is primarily stimulated during cell activation by GnRH. GnRH receptors in tumors differ from those in pituitary gonadotrophs in some aspects, in particular with regard to the transmembrane signaling cascade. The intramembranous phenomena that occur independently of the contribution of other organelles upon tumoral GnRH receptor engagement include (i) activation of phosphotyrosine phosphatase and loss of phosphotyrosine from the endogenous membrane protein and (ii) phosphoinositide and perhaps sphingomyelin cleavage producing lipid-originated second messengers. GnRH has also been demonstrated to increase Fas ligand expression within plasma membrane, which is known to promote apoptotic cell death through attack on Fas-positive cells within tumors. The Fas-Fas ligand complex might, at least in part, account for the antiproliferative action of the hormone. An understanding of the relationship between the extracellular (hormonal) stimuli that leads to cell death and the intracellular events regulating growth arrest on GnRH action may fundamentally help clarify the therapeutic approach to all hormone-dependent carcinomas that respond to stimuli that lead to apoptosis. In this chapter, we review the recent literature and the results of our studies on GnRH-induced membrane events and summarize what is currently known about this promising antiproliferative function.

Primary and salvage therapy with LH-RH analogues in ovarian cancer

The efficacy of modern surgical and chemotherapeutic options for the treatment of ovarian cancer is still unsatisfactory. In spite of the availability of new cytotoxic agents, the majority of ovarian cancer patients will finally die of chemoresistant disease. LH-RH agonists in conventional doses have been shown to induce objective responses in approximately 9% of patients with refractory ovarian cancer and disease stabilization in 26% of these women. As toxicity of LH-RH agonists is low or absent, and since their efficacy is not strikingly inferior to that of experimental chemotherapy, they have a vital indication in the salvage situation. A trial is presently being performed among platinum/taxol-refractory patients, comparing the impact of the LH-RH agonist leuprorelin and that of the cytotoxic agent treosulfane on survival and quality of life. The addition of LH-RH agonists in conventional doses to standard first-line surgical and chemotherapy does not improve relapse-free and overall survival. For many years it has been suggested that LH-RH agonists inhibit proliferation of ovarian cancer by suppressing endogenous gonadotropins, which were considered to be mitogenic in this malignancy. Recent experimental and clinical data have made this hypothesis questionable. In contrast, a large body of experimental evidence has emerged during the past few years indicating that LH-RH agonists and antagonists directly inhibit proliferation of ovarian cancer through LH-RH receptors expressed by 80% of these tumors. To exploit these direct antiproliferative effects of LH-RH analogues, higher tissue concentrations are necessary than those achieved with the conventional doses used today. Alternative routes of administration or higher systemic doses of potent LH-RH antagonists, such as Cetrorelix, might improve the efficacy of this approach. Clinical trials addressing this issue are under way. Finally, the LH-RH receptors expressed by ovarian cancers could be employed for targeted chemotherapy using cytotoxic LH-RH analogues. This approach has been shown to be effective in experimental models and might be tested in clinical trials in the near future.

Luteinizing hormone-releasing hormone analogs: their impact on the control of tumorigenesis

The development of the luteinizing hormone-releasing hormone (LH-RH) agonists and antagonists and the principles of their clinical use were reviewed. In the 28 years that have elapsed since the elucidation of the structure of LH-RH, various applications in gynecology, reproductive medicine, and oncology have been established for LH-RH agonists and antagonists. These clinical applications are based on inhibition of the pituitary and the gonads. The advantage of the LH-RH antagonists is due to the fact that they inhibit the secretion of gonadotropins and sex steroids immediately after the first injection and thus achieve rapid therapeutic effects in contrast to the agonists, which require repeated administration. LH-RH antagonists should find applications in the treatment of benign gynecologic disorders and benign prostatic hypertrophy and in assisted reproduction programs. The primary treatment of advanced androgen-dependent prostate cancer is presently based on the use of depot preparations of LH-RH agonists, but antagonists like Cetrorelix already have been tried successfully. Antagonists of LH-RH might be more efficacious than agonists in treatment of patients with breast cancer as well as ovarian and endometrial cancer. Recently, practical cytotoxic analogs of LH-RH that can be targeted to LH-RH receptors on tumors have been synthesized and successfully tested in experimental cancer models. Targeted cytotoxic LH-RH analogs show a great promise for therapy of prostate, breast, and ovarian cancers.

Rational use of agonists and antagonists of luteinizing hormone-releasing hormone (LH-RH) in the treatment of hormone-sensitive neoplasms and gynaecologic conditions

Analogues of luteinizing hormone-releasing hormone (LH-RH) have made possible new approaches to the treatment of some hormone-dependent cancers and diseases and conditions which result from inappropriate sex hormone levels. In the fields of both gynaecology and oncology, the development of sustained delivery depot systems has played a key role in the clinical use of LH-RH agonists and will be also essential for the LH-RH antagonists. Clinical results show that therapy with agonists of LH-RH is the preferred method of treatment for men with advanced prostate cancer. For prostate cancer and other indications, the new LH-RH antagonists such as Cetrorelix may offer an advantage based on the fact that they inhibit LH, FSH and sex-steroid secretion from the start of the administration and thus reduce the time of the onset of therapeutic effects. The use of antagonists would avoid the temporary clinical "flare-up" of the disease which can occur with the agonists in men with prostate cancer. The rapid shrinkage of the prostate and improvement in urinary symptoms obtained with Cetrorelix in men with benign prostatic hyperplasia (BHP) suggests that LH-RH antagonists offer a therapeutic alternative in patients who are considered poor surgical risks. Various experimental and clinical studies suggest that analogues of LH-RH might be useful for treatment of premenopausal women with oestrogen-dependent breast cancer. LH-RH antagonists such as Cetrorelix could be also considered for hormonal therapy of epithelial ovarian cancer which responds only marginally to the agonists, and for treatment of endometrial cancer. Many investigators have reported beneficial effects of LH-RH agonists in the treatment of patients with leiomyomas. LH-RH antagonists also appear to be promising for therapy of uterine leiomyomas, and in addition might be useful for treatment of endometriosis and polycystic ovarian disease (PCOD). LH-RH agonists have been employed in in vitro fertilization and embryo transfer (IVF-ET) programs to prevent a premature rise in LH and various results suggest that the use of antagonist Cetrorelix in assisted reproduction procedures, could be even more advantageous. For most of these indications, the use of sustained release depot preparations will be required.

Luteinizing hormone-releasing hormone agonist triptorelin in combination with cytotoxic chemotherapy in patients with advanced ovarian carcinoma. A prospective double blind randomized trial. Decapeptyl Ovarian Cancer Study Group

BACKGROUND

Several lines of evidence suggest that the proliferation of ovarian carcinoma might be stimulated by gonadotrophins. A number of Phase I/Phase II clinical trials have reported that the suppression of endogenous luteinizing hormone and follicle-stimulating hormone secretion by luteinizing hormone-releasing hormone (LHRH) analogs induced objective remissions and/or disease stabilization in 10-30% of patients with advanced refractory ovarian carcinoma. The current study was performed to evaluate whether the addition of LHRH agonist treatment to standard platinum-based chemotherapy could prolong survival of patients with surgically treated Stage III or IV epithelial ovarian carcinoma.

METHODS

One hundred and thirty-five patients with Stage III or IV epithelial ovarian carcinoma participated in this prospective randomized double blind trial. After cytoreductive surgery, 69 patients received monthly injections of a depot preparation of the LHRH agonist [D-Trp6] LHRH (triptorelin, 3.75 mg) and 66 patients received placebo until their deaths or termination of trial, respectively. All patients were treated with a standard platinum-based chemotherapy, and, if necessary, with second- or third-line cytotoxic regimens.

RESULTS

Endogenous gonadotrophins were reliably suppressed in patients treated with triptorelin. However, their progression free and overall survival were not significantly different from that of patients receiving placebo injections (statistical power > 80% for a difference between both groups of > or = 20%).

CONCLUSIONS

The results of this trial suggest that the suppression of endogenous gonadotrophins by conventional doses of an LHRH agonist produces no relevant beneficial effects in patients with advanced ovarian carcinoma who receive standard surgical cytoreduction and cytotoxic chemotherapy.

Ovarian epithelial tumour in gonadal dysgenesis. A case report and literature review

A patient with gonadal dysgenesis was found to have a mucinous epithelial ovarian tumour on the left side and a streak gonad on the right. The preponderance of mucinous tumours (5 of 8) over other epithelial tumours in these patients is noted but the significance is not fully understood. Two models of pathogenesis (incessant ovulation and hypergonadotrophic hypogonadism) were proposed but neither satisfactorily explains the development of the tumours. Further ultrastructural, chromosomal and molecular biological study of these tumours may help to elucidate the underlying cause and pathogenesis.

Effect of a gonadotropin releasing hormone analog on an experimental ovarian tumor: direct and indirect actions

An ovary autotransplanted into the spleen of a bilaterally ovariectomized rat develops into a luteoma, which grows under constant gonadotropin hyperstimulation. The effect of a long-acting GnRH agonist (GnRH-a), on tumor growth and hormone secretion was investigated. Two experimental models were used: Model 1: GnRH-a (0.33 mg/rat sc) or estradiol valerianate (50 micrograms/rat sc injected once a week for four weeks) was administered simultaneously with ovary implantation; Model 2: the drugs were administered after 1 month of tumor development. The treatment with estradiol was used as a control of tumor regression. Saline injected ovarian grafted rats and Sham operated animals were used as controls. In Model 1: The GnRH-a significantly inhibited tumor development (Positive tumors: Saline: 100% vs GnRH-a: 43%, p < 0.01). In Model 2: the GnRH-a and estradiol significantly reduced the volume of one month old tumors (52% and 39% of initial volumes respectively, p < 0.01). Gonadotropin secretion was significantly inhibited or its increase blunted by the GnRH-a and by estradiol treatments in both models. Estradiol and progesterone in portal blood, which collects the steroids secreted by the luteoma, were significantly reduced by GnRH-a treatment in both models. On the other hand, in tumor cells cultured "in vitro", the GnRH-a was able to inhibit the LH induced progesterone secretion in a concentration dependent way. These results clearly show that the GnRH-a is effective in inhibiting tumor growth or reducing its volume, when already developed; furthermore, it suppresses tumor steroid hormone production. These actions were exerted at both the hypophyseal and tumor levels.

A phase II trial of D-Trp-6-LHRH (decapeptyl) in pretreated patients with advanced epithelial ovarian cancer

Fourteen patients with advanced ovarian cancer who failed chemotherapy received a long-acting LHRH agonist. All the patients had been previously operated on and all had received at least one regimen of chemotherapy. Duration of decapeptyl administration was between 1 month and 28 weeks. There were no complete or partial responses. Eight patients (57%) had disease stabilization with a median progression-free interval of 14 weeks (range 4-28 weeks). All other patients developed a clear progressive cancer after the first injection of LHRH agonist. Three of these patients are still alive and receiving other forms of chemotherapy (median follow-up after the end of LHRH treatment was 11.5 months). The regimen was well tolerated with only mild toxicity observed (hot flushes in 2 patients). Although D-Trp-6-LHRH (Decapeptyl) was well tolerated, it had insignificant activity in treating patients with epithelial cancer that was resistant or relapsed after first-line platinum-based chemotherapy.

Leuprorelin. A review of its pharmacology and therapeutic use in prostatic cancer, endometriosis and other sex hormone-related disorders

Leuprorelin (leuprolide acetate) is a gonadotrophin-releasing hormone (GnRH) analogue used to treat a wide range of sex hormone-related disorders including advanced prostatic cancer, endometriosis and precocious puberty. It acts primarily on the anterior pituitary, inducing a transient early rise in gonadotrophin release. With continued use, leuprorelin causes pituitary desensitisation and/or down-regulation, leading to suppressed circulating levels of gonadotrophins and sex hormones. Clinical trials in men with advanced prostatic cancer demonstrate that leuprorelin (usually monthly depot injections of 3.75 or 7.5 mg) is less likely to cause serious adverse cardiovascular effects than diethylstilbestrol, and has comparable efficacy to bilateral orchiectomy or other GnRH analogues. Therefore, the choice between leuprorelin and orchiectomy may be made on the basis of the patient's treatment preference, along with specific patient characteristics and cost implications. Monthly intramuscular or subcutaneous administration of depot leuprorelin 3.75 mg was superior to placebo, and comparable to oral danazol 800 mg/day or intranasal buserelin 900 micrograms/day, in achieving objective and subjective responses in women with endometriosis. Thus, leuprorelin is an effective alternative to other treatments for women with endometriosis, but the recommended duration of its use in this clinical setting is limited to 6 months because it reduces bone mineral density. In children with central precocious puberty, leuprorelin (usually monthly intramuscular or subcutaneous injections of depot leuprorelin 3.75 to 15mg) decreases mean growth velocity and signs of sexual maturation and increases predicted adult height compared with baseline measurements. Although effects on final adult height are predicted from available data and require confirmation in long term follow-up studies, the absence of effective alternatives to GnRH analogues makes leuprorelin a first-line therapy for children with this rare disease. In women with uterine leiomyomata, monthly intramuscular administration of depot leuprorelin 3.75 mg for 6 months markedly reduces uterine volume and fibroid-related symptoms, but, as with other GnRH analogues, these effects dissipate following discontinuation of the drug. As adjuvant therapy in women undergoing in vitro fertilisation or gamete intrafallopian transfer, leuprorelin (usually 0.5 to 1 mg/day subcutaneously) reduces the risk of cancelled cycles for oocyte retrieval by preventing premature luteinisation. While some studies demonstrate an improvement in intermediate end-points such as increased number of mature oocytes retrieved and embryos available for transfer, a significant effect has not been demonstrated on the rate of live births per stimulated cycle.(ABSTRACT TRUNCATED AT 400 WORDS)

Expression of gonadotropin-releasing hormone receptor in human epithelial ovarian carcinoma

We have previously demonstrated the presence of gonadotropin-releasing hormone (Gn-RH) messenger ribonucleic acid (mRNA) in epithelial ovarian carcinoma. In this study, the expression of Gn-RH receptor (Gn-RHR) was investigated in human ovarian carcinoma and human ovarian carcinoma cell line. Gn-RHR was determined by [3H]Gn-RH binding assay. Gn-RHR mRNA was determined by reverse transcription-polymerase chain reaction using oligonucleotide primers synthesized based on published human Gn-RHR sequence. Specific Gn-RH binding sites were shown to be present in plasma membrane isolated from five ovarian mucinous cystadenocarcinoma samples and one serous cystadenocarcinoma (Kd = 15.3 +/- 8.08 nmol/L). Gn-RHR mRNA was detected in four mucinous cystadenocarcinoma specimens, one serous cystadenocarcinoma, and SK-OV-3 cells, but not in white blood cells. These results suggest that Gn-RH may play an autocrine regulatory role in the growth of ovarian carcinoma.

Inhibition of growth of OV-1063 human epithelial ovarian cancer xenografts in nude mice by treatment with luteinizing hormone-releasing hormone antagonist SB-75

Female athymic nude mice bearing xenografts of OV-1063 human epithelial ovarian cancer cell line were treated with potent luteinizing hormone (LH)-releasing hormone (LH-RH) antagonist SB-75 (Cetrorelix; [Ac-D-Nal(2)1, D-Phe(4 CI)2, D-Pal(3)3, D-Cit6, D-Ala10]LH-RH in which Ac-D-Nal(2) = N-acetyl-3-(2-naphthyl)-D-alanine, D-Phe(4CI) = 4-chloro-D-phenylalanine, D-Pal(3) = 3-(3-pyridyl)-D-alanine, and D-Cit = D-Citrulline) or with the agonist [D-Trp6]LH-RH. In the first experiment, SB-75 and [D-Trp6]LH-RH were administered in the form of microcapsules releasing 60 and 25 micrograms/day, respectively. In the second study, the analogs were given by daily s.c. injections in doses of 100 micrograms/day. In both experiments, tumor growth, as measured by reduction in tumor volume, percentage change in tumor volume, tumor burden, and increase in tumor doubling time, was significantly inhibited by treatment with SB-75 but not with [D-Trp6]LH-RH. Uterine and ovarian weights were reduced and serum LH levels decreased by administration of either analog. Chronic treatment with SB-75 greatly reduced the concentration of receptors for epidermal growth factor and insulin-like growth factor I in tumor cell membranes, a phenomenon that might be related to tumor growth inhibition. It is possible that the antitumoral effects of SB-75 on OV-1063 ovarian cancers are exerted not only through the suppression of the pituitary-gonadal axis, but also directly. In view of its strong inhibitory effect on the growth of OV-1063 ovarian cancers in vivo, the potent LH-RH antagonist SB-75 might be considered for possible hormonal therapy of advanced epithelial ovarian carcinoma.

Inhibition of human epithelial ovarian cancer cell growth in vitro by agonistic and antagonistic analogues of luteinizing hormone-releasing hormone

In this study, we investigated the effects of luteinizing hormone-releasing hormone (LH-RH) agonist [D-Trp6]LH-RH, LH-RH antagonist [Ac-D-Nal(2)1,D-Phe(pCl)2,D-Pal(3)3,D-Cit6,D-Ala10]LH-RH (SB-75), and estradiol on the growth of human epithelial ovarian cancer cell line OV-1063. Cells were cultured under estrogen-deprived conditions. Estradiol inhibited cell proliferation, as measured by cell number at 10(-9)-10(-7) M and [3H]thymidine incorporation into DNA at 10(-13)-10(-8) M. Both LH-RH analogs inhibited cell growth dose dependently in the range 10(-8)-10(-5) M, but SB-75 induced a greater growth inhibition than [D-Trp6]LH-RH. In OV-1063 cells, 125I-labeled [D-Trp6]LH-RH was bound to one class of specific, saturable binding sites with high affinity (Kd = 1.4 +/- 0.3 nM) and low capacity (4000 binding sites per cell). 125I-labeled [D-Trp6]LH-RH could be displaced by unlabeled [D-Trp6]LH-RH and SB-75, suggesting that both analogs are bound to the same receptor on OV-1063 cells. Ligand binding was dependent on time and temperature. Receptor internalization assay showed that the ligand-receptor complex was internalized at 37 degrees C, which indicates the presence of biologically active LH-RH receptors on OV-1063 cells. These results suggest that estradiol and LH-RH analogs can suppress the growth of OV-1063 human epithelial ovarian cancer cells by a direct action and that the inhibitory effect of LH-RH analogs is mediated through the high-affinity LH-RH receptors.

Peptide analogues alter the progression of premalignant lesions, as measured by Photofrin fluorescence

Somatostatin analogue RC-160 and bombesin/gastrin-releasing peptide antagonist RC-3095 were infused at 2 micrograms per day via miniosmotic pumps implanted s.c. in hamsters with premalignant disease to examine the effect of these peptides on cancer promotion and progression. These analogues have been shown to inhibit growth of certain tumors, especially those that overexpress tyrosine kinase activity. Progression of premalignant lesions initiated by applying 0.5% 9,10-dimethyl-1,2-benzanthracene (DMBA) to the hamster buccal cheek pouch was measured by Photofrin-induced fluorescence 24 hr after injecting the porphyrin (1.0 mg/kg) by using in vivo fluorescence photometry. This method of monitoring progression was reaffirmed by the observations that fluorescence increased significantly as compared with controls in lesions receiving 4 additional weeks of continuous promotion by DMBA application (P < 0.01 in two independent trials) and in lesions receiving transient promotion by laser incision (P < 0.01 and < 0.05 at the same time in the two trials). Twelve weeks after treatment, fluorescence had decreased significantly among animals treated for 2 weeks with RC-3095 (control, 0.53 +/- 0.03 V vs. RC-3095, 0.28 +/- 0.03 V; P < 0.0005) or with RC-160 (control, 0.85 +/- 0.03 V vs. RC-160, 0.24 +/- 0.03 V; P < 0.0001). These data were obtained 20 weeks after DMBA initiation. Thus, treatment with RC-160 and RC-3095 decreased the progression, measured by fluorescence, compared with control animals. In addition, there was also an absolute continuous decrease in fluorescence for the 22 weeks after the cessation of RC-160 treatment. That the changes in tumor progression produced by RC-160 extended beyond the treatment period supports the hypothesis that the changes were irreversible. Histopathological analysis revealed normal tissue and/or mild-moderate dysplasia in hamster buccal mucosa treated with the RC-160 (an improvement compared to pretreatment), whereas 40% of the animals receiving no treatment after DMBA initiation developed invasive squamous cell carcinomas after 20 weeks. These results show that the antagonists of bombesin/gastrin-releasing peptide can delay the development of malignancies and the agonists of somatostatin can potentially reverse this development.

GnRH agonist analog therapy in advanced/recurrent granulosa cell tumors: further evidence of a role of inhibin in monitoring response to treatment

Five patients with advanced ovarian granulosa cell malignancies resistant to cytotoxic chemotherapy were treated with monthly subcutaneous injections of long-acting gonadotropin releasing hormone (GnRH) agonist analog. One partial response and one stabilization of the disease were observed. In three patients, the tumor continued to progress. Treatment response was monitored with serum inhibin assay. Four patients had high serum inhibin concentrations at the beginning of GnRH analog treatment, while one patient had an inhibin-negative tumor. In three of four patients, serum inhibin remained relatively constant, or decreased during the first 3 months of therapy. It subsequently increased, in parallel with clinical deterioration. Further clinical trials with GnRH analogs are warranted in this malignancy in which serum inhibin appeared to be a clinically valuable tumor marker.

A phase II trial of goserelin (Zoladex) in relapsed epithelial ovarian cancer

Thirty patients with advanced epithelial ovarian cancer were treated with the luteinising hormone releasing agonist, goserelin. There were two partial responses lasting 40 and 105 weeks respectively. In addition five patients had disease stabilisation lasting 25, 35, 40, 66 and 70 weeks respectively and 23 patients had progressive disease. No significant or unexpected toxicities occurred. This minimally toxic therapy halted disease progression for 6 months or more in 23% of patients, the majority of whom were heavily pretreated. There were five early deaths due to disease progression. The use of goserelin in patients with epithelial ovarian cancers resistant to or relapsing soon after first line platinum based chemotherapy needs to be further evaluated.

Intracellular actions of gonadotropic and peptide hormones and the therapeutic value of GnRH-agonists in ovarian cancer

During the last two decades, considerable experimental evidence has been collected indicating that epithelial ovarian cancer might be gonadotropin dependent. LH and FSH receptors have been described in some of these tumors. The proliferation of ovarian cancer cells could be stimulated in vitro by gonadotropins. Suppression of endogenous LH and FSH secretion by GnRH-agonist treatment inhibited the growth of experimental or heterotransplanted ovarian cancers in various animal models. A number of recent phase II clinical trials have shown that the application of GnRH-agonists can lead to remission or stable disease in patients with relapsed advanced ovarian cancer. At present, prospective controlled clinical studies are being performed to assess the efficacy of GnRH-agonist treatment in addition to conventional surgical and cytostatic therapy in ovarian cancer in FIGO stages III and IV. Also, direct effects of GnRH analogues on ovarian cancer seem possible: a GnRH-like protein has been found in the human ovary. Our group discovered and partially characterized a specific GnRH-binding site (mol. wt 63.2 kDa) in ovarian cancer which is very similar to other human extrapituitary GnRH-binding sites of the low affinity, high capacity type, e.g. in breast cancer or the placenta. Recently, other groups have described also high affinity GnRH-agonist binding sites in ovarian cancer as well as in other extrapituitary tissues. First results from our laboratory indicate that the proliferation of certain ovarian cancer cell lines in vitro is reduced by both agonistic and antagonistic analogues of GnRH. Other authors were able to inhibit gonadotropin-induced in vitro proliferation of ovarian cancer cell lines by co-incubation with a GnRH-agonist.(ABSTRACT TRUNCATED AT 250 WORDS)

LHRH-receptors and LHRH-agonist treatment in ovarian cancer: an overview

Considerable evidence exists that ovarian cancer might be gonadotrophin-dependent. Receptors for LH and FSH have been discovered in these tumors. Proliferation of ovarian cancer cells in vitro could be stimulated by gonadotrophins. Withdrawal of LH and FSH in animal models of ovarian cancer inhibited growth of these tumors. Phase-II clinical studies have shown that suppression of endogenous gonadotrophins by LHRH-agonists can be beneficial in women with advanced ovarian cancer. Respective controlled clinical trials are performed at present. Also direct effects of LHRH analogues on ovarian tumors have been reported. An LHRH like protein was found in human ovarian tissue. We discovered a specific LHRH binding site (mol. wt 63.2 kDa) in ovarian cancer tissue which is very similar to other human extrapituitary LHRH binding sites, of the low-affinity, high-capacity type, e.g. in breast cancer and the placenta. In the latter tissues, LHRH or a related substance has been proposed as an autocrine regulator of cellular function. If this was also the case in ovarian cancer, direct effects of LHRH analogs on the tumor cells could be used as additional therapeutical points of attack.