Effect of a Somatostatin Analogue on Trophic Hormone Levels in Acromegalic Patients with Elevated hGH after Adrenomectomy and Treatment with Bromocriptine

Five female acromegalic patients who had undergone surgical adenomectomy, but still had elevated hGH serum levels, were treated with bromocriptine, 5-15 mg daily, for at least 4 months without a satisfactory response. In an attempt to lower serum hGH levels, p-NH2-Phe4-D-Trp8-somatostatin was administered, 100 micrograms as an i.v. bolus, followed by infusion of 250 micrograms over a 4 hour period. The analogue decreased hGH levels by about 50% in 3 out of 5 patients, both during bromocriptine treatment and also in its absence. Of the remaining two patients, one showed a decrease in hGH levels in response to the analogue only during bromocriptine treatment and the other only without it. Saline infusion after bromocriptine administration did not induce a decrease in hGH levels in three of these patients. Somatostatin analogue caused a fall in serum insulin levels in all but one patient, who had diabetes mellitus and in whom serum insulin was undetectable. Both hGH and insulin levels showed a significant rebound after infusion of the analogue, but returned to basal levels within 24 hours. Prolactin did not change during the analogue infusion in 4 patients with normal PRL levels. However, in one patient in whom prolactin and hGH levels were elevated during bromocriptine treatment, the infusion of somatostatin analogue decreased both hormones. The analogue induced no changes in serum TSH, FSH and LH levels of any of the patients.

New approaches to therapy of cancers of the stomach, colon and pancreas based on peptide analogs

Cancers of the stomach, colon and exocrine pancreas are major international health problems and result in more than a million deaths worldwide each year. The therapies for these malignancies must be improved. The effects of gastrointestinal (GI) hormonal peptides and endogenous growth factors on these cancers were reviewed. Some GI peptides, including gastrin and gastrin-releasing peptide (GRP) (mammalian bombesin), appear to be involved in the growth of neoplasms of the GI tract. Certain growth factors such as insulin-like growth factor (IGF)-I, IGF-II and epidermal growth factor and their receptors that regulate cell proliferation are also implicated in the development and progression of GI cancers. Experimental investigations on gastric, colorectal and pancreatic cancers with analogs of somatostatin, antagonists of bombesin/GRP, antagonists of growth hormone-releasing hormone as well as cytotoxic peptides that can be targeted to peptide receptors on tumors were summarized. Clinical trials on peptide analogs in patients with gastric, colorectal and pancreatic cancers were reviewed and analyzed. It may be possible to develop new approaches to hormonal therapy of GI malignancies based on various peptide analogs.

Hypothalamic hormones and cancer

The use of peptide analogs for the therapy of various cancers is reviewed. Inhibition of the pituitary-gonadal axis forms the basis for oncological applications of luteinizing hormone-releasing hormone (LH-RH) agonists and antagonists, but direct effects on tumors may also play a role. Analogs of somatostatin are likewise used for treatment of various tumors. Radiolabeled somatostatin analogs have been successfully applied for the localization of tumors expressing somatostatin receptors. Studies on the role of tumoral LH-RH, growth hormone-releasing hormone (GH-RH), and bombesin/GRP and their receptors in the proliferation of various tumors are summarized, but the complete elucidation of all the mechanisms involved will require much additional work. Human tumors producing hypothalamic hormones are also discussed. Treatment of many cancers remains a major challenge, but new therapeutic modalities are being developed based on antagonists of GH-RH and bombesin, which inhibit growth factors or their receptors. Other approaches consist of the use of cytotoxic analogs of LH-RH, bombesin, and somatostatin, which can be targeted to receptors for these peptides in various cancers and their metastases. These new classes of peptide analogs should lead to a more effective treatment for various cancers.

Peptide analogs in the therapy of prostate cancer

The use of peptide analogs in the therapy of prostate cancer is reviewed. The preferred primary treatment of advanced androgen-dependent prostate cancer is presently based on the use of depot preparations of LH-RH agonists. This treatment is likewise recommended in patients with rising PSA levels after surgery or radiotherapy. LH-RH agonists with or without antiandrogens can be also utilized prior to or following various local treatments in patients with clinically localized prostate cancer and at high risk for disease recurrence. LH-RH antagonists like Cetrorelix are in clinical trials. However, most patients with advanced prostatic carcinoma treated by any modality of androgen deprivation eventually relapse. Treatment of relapsed androgen-independent prostate cancer remains a major challenge, but new therapeutic modalities are being developed based on antagonists of growth hormone-releasing hormone (GH-RH) and bombesin, which inhibit growth factors or their receptors. Another approach consists of cytotoxic analogs of LH-RH, bombesin, and somatostatin containing doxorubicin or 2-pyrrolinodoxorubicin, which can be targeted to receptors for these peptides found in prostate cancers and their metastases. These cytotoxic analogs inhibit growth of experimental androgen-dependent or -independent prostate cancers and reduce the incidence of metastases. A rational therapy with peptide analogs could be selected on the basis of receptors present in biopsy samples. The approaches based on peptide analogs should result in a more effective treatment for prostate cancer.

Efficacy and safety of luteinizing hormone-releasing hormone antagonist cetrorelix in the treatment of symptomatic benign prostatic hyperplasia

As the life expectancy for men increases, more cases of benign prostatic hyperplasia (BPH) will be expected. Symptomatic BPH causes morbidity and can lower the quality of life. We investigated whether short term administration of the LH-releasing hormone antagonist cetrorelix could provide an improved treatment for men with BPH. Thirteen patients with moderate to severe symptomatic BPH were treated with cetrorelix (5 mg, s.c., twice daily for 2 days followed by 1 mg/day, s.c., for 2 months). Patients were evaluated at baseline, during treatment, and up to 18 months after therapy. We determined the effects of cetrorelix on the International Prostate Symptom Score (IPSS), Quality of Life score, sexual function, prostate size, uroflowmetry, and hormonal levels. Treatment with cetrorelix produced a decline of 52.9% (P < 0.0001) in IPSS, a 46% improvement in the Quality of Life score (P < 0.001), a rapid reduction of 27% (P < 0.006) in prostatic volume, and an increase in peak urinary flow rates by 2.86 mL/s. Serum testosterone fell to castrate levels on day 2, but was inhibited only by 64-74% during maintenance therapy, and after cessation of treatment returned to normal. During long term follow-up, most patients continued to show a progressive improvement in urinary symptoms (decline in IPSS from 67% to 72% at weeks 20 and 85, respectively) and an enhancement of sexual function, and prostatic volume remained normal. Our study demonstrates that in patients with symptomatic BPH, treatment with cetrorelix is safe and produces long term improvement.

Treatment of uterine leiomyomas with luteinizing hormone-releasing hormone antagonist Cetrorelix

The efficacy of the luteinizing hormone-releasing hormone antagonist Cetrorelix (SB-75) in the medical management of uterine leiomyomas (fibromas) was evaluated. Cetrorelix was administered to 18 pre-menopausal women with myomas with a mean age of 33.3 years, who had been candidates for hysterectomy. The initial dose of Cetrorelix was 5 mg twice daily s.c. for the first 2 days and thereafter 0.8 mg was given twice daily s.c. for at least 3 months. The mean duration of the treatment was 4.4 months. Before the therapy with Cetrorelix, the mean uterine volume, measured by ultrasonography, was 395.4 +/- 69.2 ml (range 89-1166). Sixteen patients showed a progressive reduction in uterine volume from 410.4 +/- 77.1 to a mean of 230.8 +/- 52.6 ml at 3 months. All patients became amenorrhoeic and had hot flushes. After treatment with Cetrorelix, a surgical myomectomy was performed in 12 women. One of the patients subjected to myomectomy after therapy with Cetrorelix became pregnant. These patients have been followed for up to 25 months and only in one case has the uterine volume increased after therapy. Three patients had good responses to therapy with Cetrorelix and it was decided to follow them only by observation. One patient became pregnant 2 months later. In the other patient, the uterine volume remained unchanged for the duration of the follow-up of 2 years and the third patient showed an increase after 21 months. In three patients, it was necessary to perform total hysterectomy. In 14 patients, serum concentrations of luteinizing hormone, follicle stimulating hormone and oestradiol decreased after the administration of the first dose of Cetrorelix and continued at subnormal values throughout therapy. In 15 patients who were not subjected to total hysterectomy, menstrual function returned at 1 month after cessation of treatment. Overall results support the use of Cetrorelix for the management of uterine leiomyomas.

Development and applications of luteinizing hormone-releasing hormone antagonists in the treatment of infertility: an overview

Luteinizing hormone-releasing hormone (LHRH) plays a crucial role in controlling the ovarian cycle in women. By modification of the molecular structure of this decapeptide, analogues were synthesized with agonistic or antagonistic effects on the gonadotrophic cells of the anterior pituitary gland. The agonists, after an initial stimulatory effect ('flare up'), lead to desensitization of the gonadotrophic cells and a reduction in the number of LHRH receptors on the cell membrane ('down-regulation'), while the antagonists produce an immediate effect by competitive blockade of the LHRH receptors. After administration of LHRH antagonists, the serum levels of FSH and LH decrease within hours. Nevertheless, the adenohypophysis maintains its responsiveness to an LHRH stimulus ('pituitary response') after pretreatment with an antagonist. This different pharmacological mechanism of LHRH antagonists makes possible new approaches to ovarian stimulation and to the therapy of sex steroid dependent diseases. The premature LH surge, the main cause of cancellation during induction of superovulation in assisted reproduction technology (ART) programmes, can be abolished by short term application of an LHRH antagonist associated with a reduced human menopausal gonadotrophin (HMG) requirement for ovarian stimulation. A future approach to ART might be based on the combination of pretreatment with an LHRH antagonist and ovulation induction by native LHRH or an agonist. The severe side effects encountered with early LHRH antagonists, such as anaphylactoid reactions due to histamine release, are almost completely eliminated in modern antagonists, especially Cetrorelix which is presently used clinically in controlled phase II clinical studies.

Luteinizing hormone-releasing hormone antagonist cetrorelix as primary single therapy in patients with advanced prostatic cancer and paraplegia due to metastatic invasion of spinal cord

OBJECTIVES

To assess the clinical response to luteinizing hormone-releasing hormone (LH-RH) antagonist cetrorelix (SB-75) in patients with advanced carcinoma of the prostate and paraplegia due to metastatic invasion of spinal cord.

METHODS

Cetrorelix was given at two different dose regimens to 5 patients with prostatic cancer Stage D2 and paraplegia. Urologic and neurologic examinations, laboratory studies, radiography (myelography), and prostate ultrasonography were carried out. Prostate-specific antigen (PSA) and free testosterone were also measured.

RESULTS

In all patients, the neurologic symptoms regressed. The recovery of the thermic and vibratory sensation and motility of the toes was observed. The neurologic improvement continued during the treatment and at 3 months all the patients were able to walk with the aid of a cane. In 1 patient, the myelography showed that the spinal cord compression had disappeared and prostate volume assessed by ultrasonography showed a significant decrease. The bladder function greatly improved in all 5 patients during the treatment with cetrorelix. Baseline levels of luteinizing hormone fell from 9.28 to 1.0 IU/L and those of follicle-stimulating hormone (FSH) fell from 18.28 to 12 IU/L (P < 0.05) after the first day of therapy with cetrorelix. Mean levels of free testosterone were reduced from 52.4 to 14.7 pmol/L (P < 0.005) at 12 hours and to 13.1 pmol/L (P < 0.005) 3 days after the first injection of cetrorelix. A persistent inhibition of gonadotropins and testosterone was maintained during the subsequent 3 months of therapy. The high levels of PSA gradually decreased.

CONCLUSIONS

Our results show that LH-RH antagonist cetrorelix causes an immediate lowering of the serum testosterone levels in patients with prostate cancer and metastases in the spinal cord, in whom the LH-RH agonists cannot be used as single drugs because of the possibility of flare-up and appears to be appropriate for long-term therapy.

Inhibition of luteinizing hormone, follicle-stimulating hormone and sex-steroid levels in men and women with a potent antagonist analog of luteinizing hormone-releasing hormone, Cetrorelix (SB-75)

Cetrorelix (SB-75; [Ac-D-Nal(2)1, D-Phe(4Cl)2, D-Pal(3)3, D-Cit6, D-Ala10] luteinizing hormone-releasing hormone (LHRH)) is a new highly potent antagonist analog of LHRH containing the D-ureidoalkyl amino acid D-citrulline at position 6 and is free of allergenic effects. This study shows the inhibition of LH and follicle-stimulating hormone (FSH) release in normal men, postmenopausal women and patients with gonadal dysgenesis, using different doses and i.m., s.c. and i.v. routes of administration of SB-75. The mean serum levels of LH and FSH in normal men who received one single dose of 300 micrograms of SB-75 sc started to decline rapidly 1 h after its administration; the LH suppression was sustained for 14 h and that of FSH up to 24 h or longer as the samples were obtained only up to this time. The nadir for LH was reached at 14 h and that for FSH at 24 h or later after administration of the antagonist (p < 0.05). Serum levels of total and free testosterone decreased after the first hour and this inhibition was maintained for up to 14 h. The nadir for total testosterone was at 6 h and that for free testosterone was at 8 h (p < 0.001), corresponding to 56% and 60% of inhibition, respectively. In postmenopausal women, inhibition of the elevated basal serum LH and FSH levels occurred after a single injection of the antagonist analog SB-75 in doses of 75, 150, 300, 600 and 1200 micrograms using im, sc and iv routes of administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Responses to the antagonistic analog of LH-RH (SB-75, Cetrorelix) in patients with benign prostatic hyperplasia and prostatic cancer

Among new highly potent antagonistic analogs of luteinizing hormone-releasing hormone (LH-RH), containing neutral hydrophilic D-ureidoalkyl amino acids such as D-Cit and D-Hci at position 6 and free of edematogenic and anaphylactoid reactions, Ac-D-Nal(2)1, D-Ph(4Cl)2, D-Pal(3)3, D-Cit6, D-Ala10 (LH-RH) (SB-75; Cetrorelix) was shown to be one of the most powerful. In this trial, we evaluated the response to 500 micrograms SB-75 given every 12 hr subcutaneously (sc) for 4 weeks in 11 patients with benign prostatic hyperplasia (BPH), and 6 weeks in 6 prostatic cancer patients (2 stage C, 4 stage D2). In patients with BPH presenting with prostatism and urinary outflow obstruction, there was a noticeable clinical improvement after the first week of SB-75 administration. This improvement continued during the course of treatment. Before therapy with SB-75, the serum levels of prostate-specific antigen (PSA) (6.73 +/- 1.46 ng/ml), acid phosphatases, total (12.67 +/- 1.15 U/l), and prostatic (2.27 +/- 0.34 U/l), were mildly elevated, but declined to normal values at 4 weeks: (2.13 +/- 0.59 ng/ml; P < 0.01), (7.68 +/- 0.89 U/l; P < 0.01), and (1.39 +/- 0.18 U/l; P < 0.01), respectively. Mean prostatic volume assessed by ultrasonography showed a significant decrease in all patients from 67.84 +/- 8.86 to 37.92 +/- 8.52 cm3; P < 0.01, which represents a reduction of 44%. In patients with prostate cancer, after the first week of therapy with SB-75, we observed a significant decrease in bone pain, relief in urinary outflow obstruction, and reversal of the signs of prostatism. Subjective improvement continued during the following weeks of treatment, so that the patients no longer needed analgesics. PSA, acid, and alkaline phosphatases gradually fell, achieving nearly normal values at 6 weeks. Initial serum testosterone levels in BPH and prostatic cancer patients were within normal limits, but during treatment with the antagonistic analog SB-75, fell to castration values. A major fall in free testosterone levels was observed after the first dose; the maximal inhibition was seen after 6-12 hr, with a simultaneous decrease in levels of both gonadotropins. Our results show that antagonist SB-75 can be safely administered for prolonged periods of time. The rapid shrinkage of the prostate and concomitant improvement in obstructive symptoms of prostatism obtained with antagonistic analog SB-75 in patients with BPH may decrease the morbidity of prostatic surgery and offer a therapeutic alternative in men who are considered poor surgical risks.(ABSTRACT TRUNCATED AT 400 WORDS)

Inhibitory effect of a highly potent antagonist of LH releasing hormone (SB-75) on the pituitary gonadal axis in the intact and castrated rat

The biological potency of the new, highly potent antagonist [AC-D-Nal (2)1, D-Phe(4Cl)2, D-Pal(3)3, D-Cit6, D-Ala10] LH-RH (SB-75) on the pituitary-gonadal system of female castrated and intact ovulating rats was tested. Administration of a single dose (50-100 micrograms/kg BW) of the antagonist SB-75 inhibited effectively the elevated gonadotrophin levels for 48 h. Pituitary LH and FSH content was not affected by SB-75 treatment. When administered in the early afternoon of the proestrus to intact cycling rats, SB-75 blocked the preovulatory LH surge as well as the primary and secondary FSH surges. However, the secondary FSH surge was not affected by SB-75 treatment when administered on the evening of proestrus suggesting its independence from the LH-RH mechanism. A group of ovariectomized rats was chronically treated with D-Trp6-LH-RH after having been pretreated by administration of a single dose of the antagonist. The initial stimulatory release of LH and FSH initiated by injection of the LH-RH agonist was significantly reduced by pretreatment with the LH-RH antagonist. We conclude that the LH-RH antagonist SB-75 may be used effectively in the field of reproductive dysfunction and endocrinological oncology and may become an invaluable physiological probe in studying the hormonal dynamics of the reproductive endocrine axis.

Comparison of GH-stimulation by GH-RH(1-29)NH2 and an agmatine29 GH-RH analog, after intravenous, subcutaneous and intranasal administration and after pulmonary inhalation in rats

Many studies have shown that human GH-RH(1-29)NH2 possesses full intrinsic activity of GH-RH(1-44)NH2 in vitro and in vivo. This investigation was performed to evaluate the efficacy of GH-RH(1-29)NH2 given by different routes of administration in stimulating GH release in rats. In each case GH-RH(1-29)NH2 was administered intravenously, subcutaneously, intranasally and by pulmonary inhalation at two different doses to groups of seven males rats. At a dose of 150 micrograms/kg GH-RH(1-29)NH2, the magnitude of GH response was significantly higher for the pulmonary inhalation group (355 +/- 33.2 ng GH/mL) than for the subcutaneous group (246 +/- 36 ng GH/mL) or for the intranasal group (175 +/- 30 ng GH/mL). The group injected intravenously with GH-RH(1-29)NH2 at a dose of 2.5 micrograms/kg showed the highest response, GH levels reaching 877.2 +/- 115 ng/mL. A similar pattern of responses was obtained for the superactive GH-RH(1-29) agmatine29 analog, MZ-3-149, at doses that were 50 times lower. Our results indicate a high bioavailability of GH-RH(1-29)NH2 or analog MZ-3-149 administered by a convenient pulmonary inhalation route. The GH-releasing effect of GH-RH(1-29)NH2 or analog MZ-3-149 delivered by pulmonary inhalation is superior to subcutaneous and intranasal administration.

Somatostatin analogue RC-160 and LH-RH antagonist SB-75 inhibit growth of MIA PaCa-2 human pancreatic cancer xenografts in nude mice

Nude mice bearing xenografts of the MIA PaCa-2 human pancreatic cancer cell line were treated with sustained-release formulations (microcapsules) of luteinizing hormone releasing hormone (LH-RH) agonist [D-Trp6]-LH-RH, somatostatin analogue RC-160 (D-Phe-Cys-Tyr-D-Trp-Lys-Val-Cys-Trp-NH2), or combination of both analogues. Other groups of mice received daily subcutaneous injections of LH-RH antagonist SB-75 [Ac-D-Nal(2)',D- Phe(4Cl)2,D-Pal(3)3,D-Cit6,D-Ala10-LH-RH] or bombesin antagonist RC-3095. At necropsy, in mice given microcapsules releasing 25 micrograms/day of [D-Trp6]-LH-RH, tumor weight and volume were decreased, but not significantly, as compared with control mice. Microcapsules of RC-160, releasing 25 micrograms/day, significantly reduced tumor volume, percentage change in tumor volume, and tumor weight. Combination of RC-160 and [D-Trp6]-LH-RH inhibited tumor growth to a somewhat greater extent than RC-160 alone. Bombesin antagonist RC-3095, at a dose of 25 micrograms/day, did not influence the growth of tumors. In mice receiving 100 micrograms/day of antagonist SB-75, there was a significant decrease in tumor weight and volume and a significant reduction in the weight of ovaries and uteri. Specific binding of [125I]RC-160 and [125I][D-Trp6]-LH-RH, but not [125I]Tyr4-bombesin, was found on MIA PaCa-2 cells in culture. [D-Trp6]-LH-RH, SB-75, and RC-160 inhibited the growth of MIA PaCa-2 cells in vitro. Neither bombesin nor RC-3095 influenced the growth of MIA PaCa-2 cells in cultures. The results indicate that the LH-RH antagonist SB-75 could be tried for treatment of pancreatic cancer. Our findings confirm the efficacy of somatostatin analogue RC-160 in inhibiting the growth of pancreatic cancers and suggest that the combination of RC-160 and agonist [D-Trp6]-LH-RH might possibly increase the therapeutic response.

Inhibition of growth of experimental prostate cancer in rats by LH-RH analogs linked to cytotoxic radicals

The effects of hybrid cytotoxic LH-RH analogs, produced by linking anthraquinone or methotrexate to carrier LH-RH agonist [D-Lys6]LH-RH, were evaluated in Copenhagen-Fisher F1 rats bearing Dunning R-3327H prostate adenocarcinoma. The two cytotoxic LH-RH analogs T-98 [(D-Lys6)LH-RH coupled to glutaryl-2-(hydroxymethyl)anthraquinone (G-HMAQ)], and AJ-04 [(D-Lys6)LH-RH linked to methotrexate (MTX)], carrier [D-Lys6]LH-RH, or the free cytotoxic compounds MTX and G-HMAQ were administered from Alzet Osmotic minipumps for 7-8 weeks. The cytotoxic LH-RH analogs caused somewhat greater tumor growth inhibition than the carrier peptide, while anthraquinone or methotrexate alone, administered in equimolar doses, were ineffective. The inhibition of androgen sensitive organs (testes, ventral prostates, and seminal vesicles) was pronounced with both carrier and cytotoxic analogs, showing the latter to be fully hormonally active in suppressing the pituitary-gonadal axis. Histological changes were also evaluated. The inhibition of mitosis and the frequency of apoptosis were higher in tumors treated with AJ-04, T-98, [D-Lys6]LH-RH, or by castration than in those of controls. Serum hormone levels were lowered by both carrier peptide and cytotoxic analogs, LH being substantially depressed, and testosterone not detectable. These results and other findings indicate that LH-RH analogs containing cytotoxic radicals anthraquinone or methotrexate retain their hormonal activity after administration in vivo, and can effectively inhibit tumor growth. Extensive further studies are required on this new class of compounds, but apparent binding of cytotoxic LH-RH analogs to tumors such as prostate cancer, which have receptors for LH-RH, could greatly reduce peripheral toxicity of chemotherapeutic agents. This approach, based on targeted chemotherapy, might be of practical therapeutic importance for the management of advanced prostate cancers, which eventually relapse after palliative hormonal therapy.

Inhibition of growth of MCF-7 MIII human breast carcinoma in nude mice by treatment with agonists or antagonists of LH-RH

Human breast carcinoma (MCF-7 MIII), which exhibits an estrogen-independent but estrogen-responsive phenotype, was xenografted in 8-9-week-old intact female athymic nude mice without estrogen supplementation. In this model, we investigated inhibitory effects of the modern luteinizing hormone-releasing hormone (LH-RH) antagonist SB-75 and the agonist D-Trp6-LH-RH. The analogs were administered in the form of sustained delivery systems (microcapsules and microgranules). In the first experiment, treatment lasted 10 weeks. After 9 weeks of treatment, a significant inhibition of tumor volume was first found only in the group treated with SB-75, but the final tumor volume was significantly suppressed both by D-Trp6-LH-RH and SB-75. In the second experiment, treatment was started 70 days after tumor transplantation and was continued for 6 weeks. Chronic treatment with SB-75 or D-Trp6-LH-RH appeared to completely arrest tumor growth as measured by tumor volume, percentage change in tumor volume, and tumor weight. Serum estradiol was suppressed to undetectable levels and LH levels were also diminished. Histologically, the regressive changes in the treated tumors were due to the enhancement of apoptosis (programmed cell death) of tumor cells. Membrane receptor assays showed that LH-RH binding sites were down-regulated in tumor cells after treatment with SB-75 or D-Trp6-LH-RH. The results indicate that the antagonist SB-75, released from sustained delivery systems, can inhibit the growth of MCF-7 MIII tumors as effectively as the agonist D-Trp6-LH-RH, but more rapidly. In view of its immediate blockade of the pituitary-gonadal axis and the absence of side effects, the LH-RH antagonist SB-75 might be considered as a possible new hormonal agent for the treatment of breast cancer.

Treatment of experimental DMBA induced mammary carcinoma with Cetrorelix (SB-75): a potent antagonist of luteinizing hormone-releasing hormone

Cetrorelix, (Ac-D-Nal(2)1, D-Phe(4Cl)2, D-Pal(3)3, D-Cit6, D-Ala10)-LHRH (SB-75) is a new highly potent antagonist of LH-RH. In the model of DMBA-induced mammary carcinoma, this antagonist was very effective in reducing tumor mass. A rapid decrease in tumor weights to levels below 0.1 g total tumor mass was achieved with 300 micrograms/kg given sc. daily for 14 days. The weights of uteri and ovaries were reduced to about 40-50% of control values. In all treated rats the estrus cycle was interrupted and the animals remained in a state of anestrus. Microscopically, the effects of Cetrorelix on the tumors were characterized by a loss of mitotic activity, marked regression with apoptosis, an increase of stroma and differentiation towards a normal mammary architecture. On the basis of a dose-response curve, a dose of 100 micrograms/kg/d of Cetrorelix was determined as sufficient for a full antitumor response. Large DMBA-tumors with total tumor mass of about 6 g could also be treated very effectively with a dose of 100 micrograms/kg/d. To achieve a complete tumor regression, the treatment had to last 34 days. After the cessation of treatment with 100 micrograms/kg/d and regrowth of the tumors the animals were treated with the agonist Decapeptyl (Trp6-LHRH) using a dose of 50 micrograms/rat/d for 14 days. Again, the tumors responded well and regressed within 10 days. The treatment with an overlapping dose schedule of Cetrorelix and Decapeptyl showed a continuous antitumor response. A transient stimulation of tumor growth by the LH-RH agonist was not observed under these experimental conditions. In ovariectomized rats bearing DMBA-tumors, treatment with Cetrorelix and estradiol, produced no tumor growth inhibition as compared to estradiol control group, indicating that there is no estrogen nullifying effect of this antagonist on tumor cells in this model. On the basis of these results, Cetrorelix is a highly effective antitumor agent in this breast cancer model, which might also be useful under clinical conditions.

Present status of agonistic and antagonistic analogs of LH-RH in the treatment of advanced prostate cancer

The methods for treatment of advanced prostate cancer, based on the agonistic analogs of LH-RH were reviewed. New therapeutic approaches utilizing antagonistic analogs of LH-RH such as SB-75 (Cetrorelix) have been described. Analogs of LH-RH chemically linked to various cytotoxic radicals are also being developed. Combinations of LH-RH agonists or antagonists with superactive somatostatin analogues such as Octastatin (RC-160) or with bombesin/GRP antagonists are being investigated in order to delay or prevent the relapse and improve the therapy for prostate cancer.

Fibrocystic disease of the breast in premenopausal women: histohormonal correlation and response to luteinizing hormone releasing hormone analog treatment

Sixty-six patients with fibrocystic mastopathy were enrolled in the trial after being selected according to clinical, radioultrasonographic, and histologic criteria. No characteristic hormonal profile was noted in most patients (52%). Estrogen receptors or progesterone receptors, or both, were found in 57% of patients. Hormone receptor levels were correlated with atypical proliferative mastopathy (87.5%). Mastopathy was associated with a uterine fibroma or a fibromatous uterus in 73% of cases. All patients received intramuscular injections of a sustained delivery system (microcapsules) of luteinizing hormone releasing hormone agonist [D-Trp6]-LHRH, Ipsen-Biotech, Paris) for 3 to 6 months. In case of partial response at 3 months, an antiestrogen (tamoxifen, 40 mg/day, for estrogen receptor-predominant lesions) or a progestin (cyproterone acetate, 50 mg/day, for progesterone receptor-predominant lesions) was added to the luteinizing hormone releasing hormone agonist. A complete response was observed in more than half of the patients (n = 35, 53%) treated by [D-Trp6]-LHRH alone (n = 29) or associated with tamoxifen (n = 4) or cyproterone acetate (n = 2). A significant partial response was observed in 30 other patients (45%). Additionally, half of them received inhibitory drugs. The best responses were seen with cyst reformation (complete response, 100%) and fibrous block. Clinical responses to treatment with [D-Trp6]-LHRH alone were independent of hormone receptor status, but synergistic effects occurred with concomitant use of the corresponding inhibitory drugs. We conclude that chronic mastopathy, particularly when associated with uterine fibroma, can be successfully treated by luteinizing hormone releasing hormone analogs in premenopausal women.

Effect of Somatostatin on TSH levels in non-toxic sporadic goiter

Somatostatin (SS-14; growth hormone-release inhibiting hormone) was infused into eight patients with non-toxic sporadic goiter and into eleven normal control subjects. Each patient was given 150 microgram(s) of somatostatin as an intravenous bolus and 350 microgram(s) by infusion over a period of 60 minutes. Somatostatin did not lower the basal TSH levels as compared to the pre-infusion levels in this type of goiter, but produced a decrease in the TSH response to TRH during and after the infusion.

Treatment of endometriosis with a delayed release preparation of the agonist D-Trp6-luteinizing hormone-releasing hormone: long-term follow-up in a series of 50 patients

Fifty patients with proven endometriosis were treated for 6 to 9 months with a delayed release preparation of microcapsules of the luteinizing hormone-releasing hormone (LH-RH) agonist D-Trp6-LH-RH, injected intramuscularly at monthly intervals. After a transitory ovarian stimulation at the onset of treatment, serum estradiol was suppressed to menopausal levels (50 pg/mL). This state of hypogonadism was reversible after the discontinuation of treatment, and menses resumed within 4 months after the last injection. Pelvic pain was relieved during treatment in 87.5% of patients. After a follow-up period of up to 37 months, 24 patients are in clinical remission and 9 experienced recurrence of endometriosis 7 to 14 months after completing treatment. One patient failed to respond to therapy with the agonist and 7 patients were lost to follow-up. Among 16 previously infertile patients with no other factors contributing to infertility, 7 became pregnant; 2 of these pregnancies were the result of gamete intrafallopian transfers. An eighth patient without documented infertility also conceived spontaneously. Side effects due to hypoestrogenism were reported by nearly all patients. In conclusion, D-Trp6-LH-RH microcapsules are effective and easily-administered agents for the treatment of endometriosis.

Membrane receptors for peptides in experimental and human pancreatic cancers

Membrane receptors for [D-Trp6]-luteinizing hormone-releasing hormone [( D-Trp6]-LH-RH), somatostatin (SS-14), and epidermal growth factor (EGF) were investigated in experimental N-nitrosobis-(2-oxopropyl)-amine (BOP)-induced pancreatic cancers of hamsters and in specimens of normal human pancreas and human pancreatic cancer obtained from autopsies. Membrane receptors for [D-Trp6]-LH-RH were absent in the pancreas of normal hamsters, but appeared after the carcinoma was induced with BOP. Binding capacity of SS-14 receptors was lower in membranes of BOP-induced pancreatic cancers than in the normal pancreas. In the BOP-induced pancreatic cancers, the receptors were also characterized following in vivo treatment of hamsters with microcapsules of the agonist [D-Trp6]-LH-RH, somatostatin analog RC-160, and the combination of both peptides, which resulted in significant tumor inhibition. Therapy with [D-Trp6]-LH-RH and RC-160, alone or in combination, decreased the binding capacity of receptors for [D-Trp6]-LH-RH, but increased Bmax for SS-14. There were no significant changes in characteristics of the EGF receptor following these therapies. Membranes from human pancreatic cancers showed binding sites for [D-Trp6]-LH-RH, but no binding was detected in normal human pancreas. The presence of receptors for LH-RH in pancreatic tumors of hamster and humans raises the intriguing possibility that LH-RH could be involved in complex interactions that contribute to the appearance of pancreatic cancer. The binding capacity of receptors for SS-14 in human pancreatic cancer membranes was lower, while Bmax for EGF was higher, as compared to normal pancreas.(ABSTRACT TRUNCATED AT 250 WORDS)

Monitoring and treatment of minimal residual cancer of the prostate

In manifest prostatic carcinoma, partial and complete remissions are obtained in 14-44% of patients as judged by different sets of criteria, but in up to 61% as judged by a decrease in prostatic acid phosphatase. Moreover, this decrease is poorly correlated to that of prostatic size. Prostatic acid phosphatase is therefore considered to be a relatively non-specific tumor marker. A complete remission, i.e. a stage of minimal residual disease, is obtained in about 25% of the patients. Continued endocrine treatment involves the risk of a flare-up of the disease, which is probably small. Additionally, in minimal residual disease, prolonged maintenance treatment requires minimization of side effects. D-Trp-6-LH-RH appears to lead to less gynecomastia and thromboembolism than some other forms of adjuvant therapy.

Long-term use of an LH-RH agonist in the management of uterine leiomyomas: a study of 17 cases

Seventeen nonmenopausal women with symptomatic uterine myomas, diagnosed by clinical examination and confirmed by pelvic ultrasonography, were treated with a delayed-release microcapsule preparation of D-Trp-6-LH-RH (Decapeptyl) injected intramuscularly, every 28 days. The microcapsules were designed to release 100 micrograms/day for 30 days. The mean duration of treatment was 4.7 months (range, 1-11). In all patients, the pituitary-ovarian axis was suppressed after 1 month of treatment, and mean serum estradiol levels fell to 17.3 pg/mL (range, 5-80). There were no significant changes in serum LH and FSH levels. Fifteen patients (83%) experienced an improvement of such symptoms as abdominal pain and bleeding. Enlarged uteri decreased in 81% of patients during the treatment, and in 38% of them the decrease in uterine volume was more than 50%. Among the 12 myomas found in 10 women, 2 disappeared and 9 decreased in volume during the treatment; for 7 myomas the decrease was more than 50%. After Decapeptyl, eight patients did not require any additional therapy, four underwent surgery, and the others were treated with progestins. The side effects were mild, consisting mainly of hot flushes. Our findings suggest that Decapeptyl may be useful for the treatment of uterine myomas.

Influence of D-Trp-6-LH-RH on the survival time in patients with advanced pancreatic cancer

Carcinoma of the exocrine pancreas seems to be sex-hormone sensitive. Administration of agonistic analogs of luteinizing hormone--releasing hormone (LH-RH) creates a state of sex-hormone deficiency. Therapy with D-Trp-6-LH-RH was evaluated in 17 patients with unresectable and biopsy-proven adenocarcinoma of the pancreas (stage IV). Nine patients were male and 8 female, and the median age at diagnosis was 60 years. The majority of patients underwent a gastro-intestinal and biliary bypass. The therapy with D-Trp-6-LH-RH was started 3-31 days after bypass surgery. The analog was given at the dose of 1 mg/day subcutaneously for the first 7 days. Subsequently, the dose was reduced to 100 micrograms/day. One month after the start of the therapy the gonadotropin levels were in subnormal range. This therapy led to clinical improvement, better quality of life and an increase in survival time. The median survival time for all the groups was 7.2 months (men 7.4 months and women 6.9 months). LH-RH agonists appear to decrease pancreatic cancer growth by eliminating the stimulatory effect of sex steroids, and by direct effects on tumors. Further improvement in the clinical response in patients with inoperable pancreatic carcinoma might be possibly obtained by the combination of LH--RH agonists with modern somatostatin analogs.

Receptors for luteinizing hormone-releasing hormone, somatostatin, prolactin, and epidermal growth factor in rat and human prostate cancers and in benign prostate hyperplasia

Using sensitive multipoint micromethods, we estimated membrane receptors for [D-Trp6]-luteinizing hormone-releasing hormone ([ D-Trp6]-LH-RH), somatostatin (SS-14), human prolactin (hPRL), and epidermal growth factor (EGF) in experimental Dunning rat prostate cancers and in samples of normal human prostate, benign prostatic hyperplasia (BPH), and human prostate cancer (PC) obtained from biopsy, after prostatectomy, or at autopsy. In the Dunning R-3327 rat prostate adenocarcinoma specimens, the receptors were characterized in untreated animals and following in vivo treatment with microcapsules of the agonist [D-Trp6]-LH-RH and the somatostatin analog RC-160. Two populations of binding sites were found for [D-Trp6]-LH-RH, one with high affinity and low capacity and another with low affinity and high capacity. Treatment with [D-Trp6]-LH-RH and RC-160 alone or with the combination of these analogs increased the binding capacity (Bmax) of the low-affinity binding sites for [D-Trp6]-LH-RH and decreased Bmax for hPRL and EGF. Therapy with [D-Trp6]-LH-RH also reduced Bmax of SS-14 binding and dissociation binding constant of high-affinity binding sites for [D-Trp6]-LH-RH, whereas administration of RC-160 or the combination treatment with both analogs increased Bmax of SS-14 binding. These findings are compatible with the view that analogs of LH-RH and SS-14 might exert some direct inhibitory effects on the Dunning prostate cancer. Among 13 human BPH samples examined, only one had receptors for [D-Trp6]-LH-RH, and seven specimens exhibited binding for prolactin. [D-Trp6]-LH-RH receptors were found in all seven samples of human PC but not in any of the eight specimens of normal human prostate. All samples of normal human prostate, BPH, and human PC exhibited binding sites for EGF but not for SS-14. Our findings on the membrane receptors in the human and rat prostate cancers raise the intriguing possibility that LH-RH, acting as a growth factor, along with EGF and prolactin, might be involved in complex interactions that contribute to the promotion of prostate cancer in man.

Inhibition of the pituitary-gonadal axis by a single intramuscular administration of D-Trp-6-LH-RH (decapeptyl) in a sustained-release formulation in patients with prostatic carcinoma

For the past 6 years we used daily injection of luteinizing hormone-releasing hormone (LH-RH) agonists to treat patients with advanced prostate carcinoma. In this study we determined the hormonal response of the pituitary-testicular axis over a 2-month period and evaluated the safety and tolerance of the single intramuscular administration of sustained-release formulations of D-Trp-6-LH-RH microcapsules designed to release 50, 100, or 200 micrograms/day for over 1 month. Serum levels of LH, testosterone, and D-Trp-6-LH-RH were measured by RIA for up to 60 days in 10 patients with advanced prostatic carcinoma who had not received any previous drug therapy. After the administration of the microcapsules there was a biphasic increase in D-Trp-6-LH-RH serum levels. The maximal peak was obtained between 1 and 3 hr, and a second peak occurred between weeks 4 and 6. LH levels increased initially, with a maximal peak at 60 min, and elevated serum LH values persisted for more than 24 hr. LH levels began to fall on the second day, reaching subnormal values after 1 week. Serum testosterone rose during the first week and fell subsequently to less than 100 ng/dl. A rebound in LH and testosterone was seen about the 50th day after the microcapsule administration. Following the first week of therapy, we observed in all patients a significant decrease in bone pain, improvement in urinary flow obstruction, and a reversal of the signs of prostatism. No side effects were observed, and acceptance of the microcapsules was very good. Our results show that a single dose of D-Trp-6-LH-RH microcapsules suppresses of the pituitary-testicular axis for at least 50 days. D-Trp-6-LH-RH microcapsules facilitate the treatment and should lead to an improvement in the therapeutic response.

Induction of ovulation with D-Trp6-LHRH combined with purified FSH in patients with polycystic ovarian disease

Seventeen patients with polycystic ovarian disease (PCOD) and evidence of mild or severe ovarian hyperstimulation syndrome (OHSS) during therapy with CC/hCG, FSH/hCG or hMG/hCG were treated with D-Trp6-LHRH until medical gonadectomy was attained. Under the suppressive therapy with the GnRH agonist (GnRHa) ovulation was induced with FSH/hCG. In 15 out of 17 patients, ovulatory cycles were obtained with this new modality of treatment. Seven patients conceived (3 viable pregnancies and 4 early abortions) after the 1st treatment cycle. Fourteen of the 17 patients demonstrated symptoms of mild OHSS which did not require hospitalization. Only 1 patient developed severe OHSS after the combined treatment. Our results suggest that therapy with GnRHa, especially in its delayed release formulation, is effective for the prevention of severe ovarian hyperstimulation in PCOD patients undergoing treatment with menotropins for the induction of ovulation.

Treatment of leiomyomata uteri with D-Trp6-luteinizing hormone-releasing hormone

Suppression of the secretion of gonadal steroids by chronic administration of a superactive agonist of luteinizing hormone-releasing hormone (LH-RH) was used for treatment of leiomyomata uteri. Ten menstruating women, presenting with a total of 20 uterine leiomyomas, were treated for 3 months with daily subcutaneous injections of D-Trp6-LH-RH. Serum estradiol (E2) levels were suppressed rapidly in five patients and were decreased in other patients. At the end of therapy, leiomyomas regressed completely in three patients, while five patients showed a decrease of more than 40% in the volume of leiomyomas. The reduction in tumor size was correlated with the rapidity of the fall in serum E2 levels. In one patient, the leiomyomata increased in size during treatment, and one woman had a poor clinical response. The agonist was well tolerated and few side effects were observed. Therapy with LH-RH agonists offers an alternative in the management of some uterine leiomyomas.

Long-acting agonists of LH-RH in the treatment of large ovarian endometriomas

Reversible temporary medical oophorectomy using long-acting agonist analogs of LH-RH was tried in three infertile patients suffering from large endometriomas of the ovary. These patients had stage IV disease according to the revised 1985 classification of the American Fertility Society. D-Ala6-des-Gly10-LH-RH propylamide (D-Ala6-LH-RH PA), in a dose of 125 micrograms, was administered intramuscularly every 48 hours to one patient, and daily to the other two patients, for 22, 17, and 14 weeks, respectively. Two patients subsequently received 100 micrograms of D-Trp6-LH-RH for 4 weeks in order to compare its efficacy with D-Ala6-LH-RH PA. Clinical controls, pelvic ultrasonography, and routine laboratory tests and hormone assays were done periodically. Ultrasonography images showed a reduction in the size of endometriomas after the second or third week of treatment. This reduction was maintained throughout and continued after the period of treatment. Suppression of the pituitary and estrogen responses was obtained rapidly, but some transient increments were occasionally found. Progesterone levels always decreased and remained in the range of the early follicular phase. Most intervals of uterine bleeding were prolonged. An evident improvement of abdominal pain, dysmenorrhea, and dyspareunia was found. Administration of D-Trp6-LH-RH was more effective than D-Ala6-LH-RH PA in most of the parameters tested. After discontinuation of treatment, all three patients had a prolonged follicular phase with a normal luteal phase during the first cycle. One woman became pregnant in the fourth cycle after discontinuation of D-Ala6-LH-RH PA and delivered a normal baby.(ABSTRACT TRUNCATED AT 250 WORDS)

Therapeutic hypogonadism induced by a delayed-release preparation of microcapsules of D-Trp-6-luteinizing hormone-releasing hormone: a preliminary study in eight women with endometriosis

Eight menstrually cycling women with proven endometriosis were treated with a delayed-release preparation of the superactive agonist D-Trp-6-LH-RH in biodegradable microcapsules, administered intramuscularly at intervals of 16 to 36 days for a period of 3 to 5 months. After the first injection which caused a transient stimulatory response, a sustained hypogonadal state, characterized by an estradiol (E2) level less than 50 pg/mL, was induced in all patients by day +14.7 (range 7.19). Subsequent injections caused no more stimulation, but a continuous decrease in E2 levels was observed. In all patients, E2 levels fell to zero after the second or third injection. Gonadotropins remained in the normal range throughout the course of treatment. Hot flashes and severe dyspareunia (related to vaginal dryness) were the main side effects. Resumption of normal pituitary-ovarian activity was documented in all patients after the last injection; the end of the hypogonadal state, ovulation and menses, occurred on days 41 (range 32-59), 58 (range 51-64) and 70 (range 65-76), respectively. All patients showed a clinical improvement. Our results demonstrate that a long-lasting, reversible hypogonadism can be induced in cyclic women by intramuscular injections of D-Trp-6-LH-RH microcapsules at monthly intervals. This simple and convenient treatment should be useful in treating endometriosis and other conditions.

Responsiveness of pituitary hGH to GRH1-44 in juveniles with obesity

The response of plasma hGH to an iv bolus injection of GRH1-44 (1 microgram/kg) was studied in 14 obese juveniles with a mean overweight of 4.7 +/- 0.05 standard deviation score (SDS). Two patterns of response were observed: in all 7 adolescents with 'simple' obesity not related to any particular disorder (group A) the response was good (a mean of 11.8 +/- 2.4 ng/ml) whereas in 6 of the 7 juveniles suffering from syndromes associated with obesity (group B) the response was poor (a mean of 3.2 +/- 1.4 ng/ml). This divergence in response could not be related to a difference in the degree of overweight. These results indicate that in group B with syndromes associated with obesity there may also be a pituitary impairment in addition to the hypothalamic defect.

Persistent blockade of the pituitary-gonadal axis in patients with prostatic carcinoma during chronic administration of D-Trp-6-LH-RH

Forty patients with stage D2 prostatic carcinoma were treated for up to 30 months with D-Trp-6-LH-RH. The analog was given s.c. once daily at a dose of 1 mg/day for the first 7 days. Subsequently, the dose was reduced to 100 micrograms/day. In follow-up studies, 30 men continued this therapy for up to 24 months. Blood samples were taken before the injection of the analog and 1, 2, 4, and 6 hours later. Serum LH, FSH, and testosterone levels were measured by RIA every month for 2 years. The initial administration of 1 mg D-Trp-6-LH-RH caused a marked elevation of LH and FSH, which lasted more than 24 hours. However, 1 month later and throughout the therapy, the basal values of LH and FSH were below the normal range and no increase in serum gonadotropins levels was obtained after administration of the analog. Initial plasma testosterone was within normal limits, but during treatment with D-Trp-6-LH-RH it fell to castration levels, and no increases were seen during the 6 hours following the injection of the analog. These results show that chronic administration of D-Trp-6-LH-RH, at the doses used, blocks the pituitary-gonadal axis and that the escape phenomenon from the effects of the LH-RH agonists-induced blockade does not occur under our conditions in contrast to observations of Kerle et al with the I.C.I. Analog 118630 (8). The accumulated results reinforce the view that long-term therapy with agonists of LH-RH is the preferred alternative to surgical castration or therapy with estrogens in men with metastatic prostate cancer.

Phase II trial with D-Trp-6-LH-RH in prostatic carcinoma: comparison with other hormonal agents

Various approaches to hormonal treatment of prostate carcinoma are discussed. Eighty-one patients with prostatic carcinoma, eight with stage B, nine with stage C, and 64 with stage D disease, were treated subcutaneously daily for 3 months with the LH-RH agonist D-Trp-6-LH-RH (Decapeptyl) in order to evaluate the incidence of remissions according to WHO recommendations for oncologic trials. The findings were compared to those obtained with other hormonal therapies of prostatic carcinoma according to the statistical method of "expected response rate" as adapted by Lee and Wesley for phase II trials. Treatment with D-Trp-6-LH-RH greatly reduced serum LH and testosterone levels without raising serum prolactin. After 1-2 weeks of therapy, there was relief of subjective symptoms and a reversal of the signs of prostatism as well as a marked decrease in bone pain. At 90 days 52 patients had complete relief of prostatism and 21 had only mild signs and symptoms. Seventy patients were experiencing no bone pain and an additional six had only mild pain. Prostatic size, evaluated by rectal examination and transabdominal ultrasonography, reverted to normal in 26.4% of patients (complete remission) and was reduced by more than 50% in an additional 17.6% (partial remission), the overall rate of complete plus partial regression of prostatic enlargement being 44%. Scans showed a major improvement of bone lesions in 14.8% of cases. This response increased to 37% after more than 6 months of follow-up. Prostatic acid phosphatase levels were decreased by more than 50% in 61% of the patients, but this test appears to be a less valid marker than the lipid-associated sialic acid (LASA). The increase in LASA before treatment and a reduction after treatment can frequently be correlated with the objective volume of the neoplasms. No flare-up of the disease was encountered, and there were no side effects except for impotence. Statistical analyses of results by the method of Lee and Wesley indicated that the incidence of complete and partial regression (CR and PR) observed with D-Trp-6-LH-RH was not significantly different from that recorded in previous studies for another LH-RH analog, Buserelin. However, CR and PR obtained with D-Trp-6-LH-RH (44%) were significantly higher than with subcapsular orchiectomy (22%). Hormonal effects and some other actions of D-Trp-6-LH-RH were compared and contrasted with those produced by castration, estrogens, antiandrogens, and progestogens.(ABSTRACT TRUNCATED AT 400 WORDS)

Radioimmunoassay for 6-D-tryptophan analog of luteinizing hormone-releasing hormone: measurement of serum levels after administration of long-acting microcapsule formulations

A sensitive and specific radioimmunoassay for [6-D-tryptophan]luteinizing hormone-releasing hormone [( D-Trp6]LH-RH) was developed and used for following the rate of liberation of [D-Trp6]LH-RH from a long-acting delivery system based on a microcapsule formulation. Rabbit antibodies were generated against [D-Trp6]LH-RH conjugated to bovine serum albumin with glutaraldehyde. Crossreactivity with LH-RH was less than 1%; there was no significant crossreactivity with other peptides. The minimal detectable dose of [D-Trp6]LH-RH was 2 pg per tube. Intra- and interassay coefficients of variation were 8% and 10%, respectively. The radioimmunoassay was suitable for direct determination of [D-Trp6]LH-RH in serum, permitting the study of blood levels of the analog after single injections into normal men and after once-a-month administration of microcapsules to rats. In men, 90 min after subcutaneous injection of 250 micrograms of the peptide, serum [D-Trp6]LH-RH rose to 6-12 ng/ml. Luteinizing hormone was increased 90 min and 24 hr after the administration of the analog. Several batches of microcapsules were tested in rats and the rate of release of [D-Trp6]LH-RH was followed. The improved batch of microcapsules of [D-Trp6]LH-RH increased serum concentrations of the analog for 30 days or longer after intramuscular injection. This was accompanied by suppression of testosterone levels for more than 30 days. This radioimmunoassay should be of value for monitoring [D-Trp6]LH-RH during long-term therapy.

Treatment of advanced prostatic carcinoma with D-Trp-6-LH-RH

Twenty patients with stage D2 prostatic carcinoma were treated for up to 18 months with D-Trp-6-LH-RH. Results of more than 3 months of treatment on these 20 patients are reported. The analog was given SC once daily at a dose of 1,000 micrograms/day. All patients had bone pain and high levels of acid and alkaline phosphatase. After the first week of D-Trp-6-LH-RH administration, major decreases in bone pain and reversal of the signs of prostatism were observed. Acid phosphatase gradually fell, achieving normal values after 12 weeks. Initial plasma testosterone was within normal limits, but during treatment with D-Trp-6-LH-RH it fell to castration levels. Resting values of PRL, GH, TSH, and cortisol did not show significant changes. After TRH, TSH increased in five patients, but five did not respond. However, at 2 and 4 months, all patients released TSH in response to TRH. Two patients died during the treatment with D-Trp-6-LH-RH despite initial subjective responses and decreases in testosterone levels. The rise in acid phosphatase levels in these two patients was accompanied by a general deterioration, suggesting that they had androgen-independent cancer. One patient who developed progressive hepatic, bone, and pulmonary metastases in spite of previous orchiectomy was also treated with the analog. Three months later his acid phosphatase levels were within normal values, and partial regression of metastases was observed. These results demonstrate that D-Trp-6-LH-RH and other LH-RH agonists can be used as an effective endocrine therapy for advanced prostate carcinoma, thereby avoiding the side effects of estrogens or the psychological impact of surgical castration.

Plasma growth hormone response to synthetic GH-RH1-44 in 52 children and adults with growth hormone deficiency of various etiologies

52 patients (42 children and 10 adults) with growth hormone deficiency (GHD), grouped into four diagnostic categories, and 6 children with constitutional short stature who served as controls were tested for plasma GH response to synthetic GH-RH1-44 given in an intravenous bolus. The response was classified into three degrees according to the magnitude of the maximal rise: Good, greater than 9 ng/ml; Partial, 3.1-9.0 ng/ml; None, less than or equal to 3 ng/ml. Among the GHD patients the highest response was observed in patients with partial growth hormone deficiency (PGHD), and 60% of the children with isolated GH deficiency (IGHD) showed an increase in plasma GH levels. Nevertheless, the response of the GHD patients was lower than that in the control group. In the children and adolescents with PGHD and IGHD the response was not age related. Among those with multiple pituitary hormone deficiencies-idiopathic (MPHD-ID) there was no response in the adolescents although a hypothalamic disorder had been documented by other tests. Among those with MPHD-organic (MPHD-ORG) the GH-RH stimulated GH secretion in the patients with glioma, who had received only irradiation treatment, and in the youngest of the patients with craniopharyngioma. Of the 10 young adults tested none showed a good response. It is concluded that GH-RH is useful in differentiating between GH deficiency of hypothalamic origin and that of pituitary origin, and in selecting those patients who might benefit from long-term treatment with GH-RH in the future.

Inhibition of growth hormone and glucagon release by Phe-4-somatostatin in patients with acromegaly

We have studied growth hormone (GH), insulin (I), glucagon (Gl) and glucose in basal conditions, after somatostatin (SS) (3 micrograms/ml) and Phe-4-SS (0.75 microgram/ml) infusion and IV bolus of the latter in 3 acromegalic patients. In two patients, Phe-4-SS inhibited glucagon and growth hormone secretion in a similar way as SS, without modifying insulin secretion. These effects were short-lived and ceased after the infusion was stopped. From these results it appears that Phe-4-SS is both more potent and more specific than SS with respect to inhibition of GH and glucagon release, but it does not have prolonged biological action. Lack of suppression of GH by SS or Phe-4-SS in the acromegalic patient with post-surgical recurrence of the disease could be due to the existence of receptor abnormalities, and suggests a diversity in the physiopathology of the disease.

Differential diagnosis between hypothalamic and pituitary hGH deficiency with the aid of synthetic GH-RH 1-44

Synthetic GH-RH 1-44 administered as an intravenous bolus (1 microgram/kg) evoked a marked hGH rise (greater than 20 ng/ml) in three children with constitutional short stature and in two of eight children diagnosed as having hGH deficiency by insulin hypoglycaemia and/or clonidine tests. As judged by the intensity of the hGH response to the dose employed and the peak time, GH-RH 1-44 may be as potent as GH-RH 1-40 in children. It is concluded that GH-RH is an important addition to the endocrine armamentarium, providing the means for differentiation between hypothalamic and pituitary hGH deficiency in a simple test which is devoid of side effects.

Inhibition of the growth of some hormone dependent tumors by D-Trp6-LH-RH

We have investigated the effects of chronic administration of D-Trp6-LH-RH on the growth of various hormone dependent tumors in rats and mice. Treatment of male Copenhagen F-1 rats bearing the Dunning R-3327H prostate adenocarcinoma with 25 micrograms of D-Trp6-LH-RH bid for 21 days significantly reduced tumor weight and volume as compared to controls. Serum LH, prolactin and testosterone levels in Copenhagen F-1 rats bearing Dunning tumors were significantly decreased after treatment with D-Trp6-LH-RH. Administration of D-Trp6-LH-RH in doses of 25 micrograms/day for 21 days to mice bearing the MXT mammary carcinoma significantly decreased tumor weight and volume. In rats bearing the MT/W9A mammary adenocarcinoma, D-Trp6-LH-RH, at a dose of 25 micrograms bid for 28 days significantly decreased tumor weight and volume. Administration of D-Trp6-LH-RH in a dose of 25 micrograms/day, 3-18 days after inoculation with the tumor, inhibited the growth of the prolactin (PRL) and ACTH-secreting pituitary tumor 7315a in female Buffalo rats. In three experiments D-Trp6-LH-RH (30-60 micrograms/day) decreased tumor weight and/or volume of the Swarm chondrosarcoma. Regression of these hormone-dependent tumors in rats and mice in response to chronic administration of D-Trp6-LH-RH suggests that this compound can be used for treatment of prostate cancer and breast cancer, and also considered for the development of a new endocrine therapy for chondrosarcomas, osteosarcomas, pituitary tumors and other hormone-dependent neoplasias. The demonstration of the successful use of LH-RH agonists for the palliative management of stage C and D prostate cancer has already shown that this treatment could be employed instead of surgical orchiectomy or estrogen therapy. Preliminary clinical trials suggest that agonists of LH-RH might also be of help in the treatment of breast cancer in premenopausal women.

Antitumor effects of analogs of hypothalamic hormones in endocrine-dependent cancers

A new approach to the treatment of endocrine-dependent tumors based on analogs of hypothalamic hormones is in the early stages of development, but appears promising and significant. Administration of hypothalamic hormones can mimic hypophysectomy and gonadectomy, and is essentially devoid of side effects. A successful use of agonistic analogs of LH-RH for treatment of endocrine-dependent prostate cancer has been documented in several hundred patients. Experimental studies suggest that agonists and/or antagonists of LH-RH might be useful for treatment of breast cancer and pituitary tumors. Our work in animal models also indicates that analogs of somatostatin, alone or combined with LH-RH agonists, could be considered for therapy of chondrosarcomas, osteosarcomas, and pancreatic cancer. Experiments are in progress on the use of LH-RH analogs for treatment of ovarian cancer, neoplasms of the female genital tract, and for protection against gonadal damage during chemotherapy. These investigations should extend the concepts of endocrine treatment of cancers.