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Inhibition of estrogen-stimulated growth of uterine leiomyomas by selective estrogen receptor modulators.

Uterine leiomyoma is the most frequent gynecologic neoplasm in women. By using a panel of cell lines derived from spontaneous Eker rat leiomyomas, we examined the estrogen-responsive phenotype of these tumor cells. Leiomyoma-derived ELT cell lines proliferated in response to estrogen, and estrogen-induced cell proliferation could be inhibited by the estrogen antagonist ICI 182780 and the selective estrogen-receptor modulators (SERMs) raloxifene and tamoxifen. In addition to inhibiting cell growth, these antagonists also inhibited estrogen-induced increases in progesterone-receptor expression. These data indicate that SERMs such as raloxifene and tamoxifen act as estrogen antagonists in uterine myometrial cells and suggest that this class of compounds may be effective for treatment of this important gynecologic neoplasm.

Animals

Reproductive endocrine and endometrial effects of raloxifene hydrochloride, a selective estrogen receptor modulator, in women with regular menstrual cycles.

Previous studies of raloxifene conducted in animal models and postmenopausal women have demonstrated antiestrogenic action on the endometrium. The purpose of this first study of raloxifene in women with normal menstrual cycles was to determine its reproductive endocrine and endometrial effects. In part I, raloxifene (400 mg) was administered for 5 days in the follicular, periovulatory, or luteal phase of the menstrual cycle (n = 12). In part II, women were randomized to receive raloxifene (100 or 200 mg) for 28 days beginning on day 3 of the cycle (n = 19). All women ovulated in both parts of the study. Raloxifene did not alter the length of the menstrual cycle or the day of the LH surge. A 5-day course of raloxifene administered in any phase of the cycle elevated FSH area under the curve (AUC) for the entire cycle and estradiol AUC for the second half of the cycle compared with those in control cycles. In part II, raloxifene also appeared to increase the FSH AUC and estradiol AUC. Raloxifene decreased the number of gland mitoses in follicular phase endometrial biopsies. Subtle effects suggestive of gland-stromal dysynchrony were noted in a limited number of the secretory phase endometrial biopsies. This study has demonstrated that 1) raloxifene does not prevent ovulation in women with normal menstrual cycles; 2) ovarian estrogen production will continue, and in some cases increase, in response to raloxifene; and 3) antiestrogenic effects of raloxifene on the endometrium are subtle in the endocrine milieu of normal to high circulating estradiol concentrations.

Adult

Molecular determinants of tissue selectivity in estrogen receptor modulators.

Interaction of the estrogen receptor/ligand complex with a DNA estrogen response element is known to regulate gene transcription. In turn, specific conformations of the receptor-ligand complex have been postulated to influence unique subsets of estrogen-responsive genes resulting in differential modulation and, ultimately, tissue-selective outcomes. The estrogen receptor ligands raloxifene and tamoxifen have demonstrated such tissue-specific estrogen agonist/antagonist effects. Both agents antagonize the effects of estrogen on mammary tissue while mimicking the actions of estrogen on bone. However, tamoxifen induces significant stimulation of uterine tissue whereas raloxifene does not. We postulate that structural differences between raloxifene and tamoxifen may influence the conformations of their respective receptor/ligand complexes, thereby affecting which estrogen-responsive genes are modulated in various tissues. These structural differences are 4-fold: (A) the presence of phenolic hydroxyls, (B) different substituents on the basic amine, (C) incorporation of the stilbene moiety into a cyclic benzothiophene framework, and (D) the imposition of a carbonyl "hinge" between the basic amine-containing side chain and the olefin. A series of raloxifene analogs that separately exemplify each of these differences have been prepared and evaluated in a series of in vitro and in vivo assays. This strategy has resulted in the development of a pharmacophore model that attributes the differences in effects on the uterus between raloxifene and tamoxifen to a low-energy conformational preference imparting an orthogonal orientation of the basic side chain with respect to the stilbene plane. This three-dimensional array is dictated by a single carbon atom in the hinge region of raloxifene. These data indicate that differences in tissue selective actions among benzothiophene and triarylethylene estrogen receptor modulators can be ascribed to discrete ligand conformations.

Animals

Evaluation of the major metabolites of raloxifene as modulators of tissue selectivity.

Raloxifene (LY139481 HCl) is a selective estrogen receptor modulator (SERM) which blocks the effects of estrogen on some tissues, such as the breast and uterus, while mimicking estrogen in other tissues, such as bone. To study the origins of this unique pharmacology, we have prepared the major metabolites of raloxifene as chemical probes for examining the estrogen receptor function in vitro and in vivo. In human breast cancer cell (MCF-7) related assays, these glucuronide conjugates show little affinity for the estrogen receptor and are more than two orders of magnitude less potent at inhibiting cell proliferation than raloxifene. In non-traditional estrogen target tissue, such as bone, these metabolites are less effective than the parent at inhibiting cytokine-stimulated bone resorbing activity in rat osteoclasts or producing transforming growth factor beta-3 (TGF-beta3). In animal models, tissue distribution studies with radiolabelled metabolite indicate that conversion to raloxifene occurs readily in a variety of tissues including the liver, lung, spleen, kidney, bone and uterus. Differential conversion of metabolite in target organs, such as bone and the uterus, is not observed indicating that the origin of raloxifene's pharmacology does not result from tissue-selective deconjugation of metabolite to parent.

Adenocarcinoma

Differential Effectiveness of Adjuvant Endocrine Therapy According to Menopausal Status, Body Mass Index, and Molecular Subtype in Hormone Receptor-Positive Breast Cancer.

The effectiveness of adjuvant endocrine therapy for hormone receptor-positive (HR+) breast cancer (BC) varies according to menopausal status, body mass index (BMI), and tumor biology. We evaluated the association between selective estrogen receptor modulators (SERMs), aromatase inhibitors (AIs), and BC-specific mortality according to menopausal status, BMI, and molecular subtype in a nationwide Korean cohort. We analyzed data from 31,030 patients with HR+ BC who were registered in the Korean Breast Cancer Society Registry, diagnosed between 2000 and 2008, and followed through 2013. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for BC-specific mortality after adjusting for demographic and clinical factors. Of the 31,030 patients, 19,634 received SERM therapy, and 3,354 received AI therapy. SERM use was associated with lower BC-specific mortality in premenopausal women (HR, 0.75; 95% CI, 0.63-0.91), whereas AI therapy was more strongly associated with lower BC-specific mortality among postmenopausal women (HR, 0.76; 95% CI, 0.61-0.94). Lower BC-specific mortality was observed among patients with a BMI ≥ 23 kg/m² who received SERM (HR, 0.84; 95% CI, 0.72-0.98) or AI therapy (HR, 0.78; 95% CI, 0.62-0.99). The strongest association with lower BC-specific mortality was observed in postmenopausal women with luminal B tumors (HR, 0.59; 95% CI, 0.42-0.83). The association between adjuvant endocrine therapy and BC-specific mortality differed according to menopausal status, BMI, and molecular subtype. These findings suggest that menopausal status, BMI, and molecular subtype are important considerations when evaluating endocrine treatment strategies.

Aromatase Inhibitors

Approaches to the management of systemic lupus erythematosus.

Systemic lupus erythematosus is a difficult disease to study with a variable disease course characterized by exacerbations and remissions. A variety of biologic agents are under investigation as potential treatments for systemic lupus erythematosus, either in murine disease models or in clinical trials. These products are designed to specifically interfere with the following immunologic processes: T-cell activation and T-cell-B-cell collaboration, production of anti-dsDNA antibodies, deposition of anti-dsDNA antibody complexes, complement activation, and deposition, and cytokine activation and modulation. More aggressive interventions include gene therapy and stem-cell transplantation. Recently developed immunomodulators have been studied in patients with systemic lupus erythematosus 2'-Chlorodeoxyadenosine, mycophenolate mofetil, and leflunomide. Additional innovative pharmaceutical treatments include the mild androgen dehydroepiandrosterone, estrogen antagonists, including tamoxifen and selective estrogen receptor modulators, and the prolactin inhibitor bromocriptine. Other promising pharmaceutical interventions include products designed to inhibit synthesis of the proinflammatory mediators: prostaglandins, leukotrienes, and nitric oxide. Although previously regarded as an indication to be avoided in the development of new therapeutics, enthusiasm for studying systemic lupus erythematosus in clinical trials now exists. A variety of biologic and pharmaceutical agents offer promise as potential therapies. As with rheumatoid arthritis, development of these products will benefit from active involvement of rheumatologists and efforts to develop international consensus regarding trial methodology and outcome measures.

Animals

Effects of raloxifene on serum lipids and coagulation factors in healthy postmenopausal women.

CONTEXT: Raloxifene is a selective estrogen receptor modulator that has estrogen-agonistic effects on bone and estrogen-antagonistic effects on breast and uterus. OBJECTIVE: To identify the effects of raloxifene on markers of cardiovascular risk in postmenopausal women, and to compare them with those induced by hormone replacement therapy (HRT). DESIGN: Double-blind, randomized, parallel trial. SETTING: Eight sites in the United States. PARTICIPANTS: 390 healthy postmenopausal women recruited by advertisement. INTERVENTION: Participants were randomized to receive 1 of 4 treatments: raloxifene, 60 mg/d; raloxifene, 120 mg/d; HRT (conjugated equine estrogen, 0.625 mg/d, and medroxyprogesterone acetate, 2.5 mg/d); or placebo. MAIN OUTCOME MEASURES: Change and percent change from baseline of lipid levels and coagulation parameters after 3 months and 6 months of treatment. RESULTS: At the last visit completed, compared with placebo, both dosages of raloxifene significantly lowered low-density lipoprotein cholesterol (LDL-C) by 12% (P < .001), similar to the 14% reduction with HRT (P < .001). Both dosages of raloxifene significantly lowered lipoprotein(a) by 7% to 8% (P < .001), less than the 19% decrease with HRT (P<.001). Raloxifene increased high-density lipoprotein-2 cholesterol (HDL2-C) by 15% to 17% (P < .05), less than the 33% increase with HRT (P < .001). Raloxifene did not significantly change high-density lipoprotein cholesterol (HDL-C), triglycerides, or plasminogen activator inhibitor-1 (PAI-1); whereas HRT increased HDL-C by 11% and triglycerides by 20%, and decreased PAI-1 by 29% (for all, P < .001). Raloxifene significantly lowered fibrinogen by 12% to 14% (P < .001), unlike HRT, which had no effect. Neither treatment changed fibrinopeptide A or prothrombin fragment 1 and 2. CONCLUSIONS: Raloxifene favorably alters biochemical markers of cardiovascular risk by decreasing LDL-C, fibrinogen, and lipoprotein(a), and by increasing HDL2-C without raising triglycerides. In contrast to HRT, raloxifene had no effect on HDL-C and PAI-1, and a lesser effect on HDL2-C and lipoprotein(a). Further clinical trials are necessary to determine whether these favorable biochemical effects are associated with protection against cardiovascular disease.

Aged

Development of clinical practice guidelines for prevention and treatment of osteoporosis.

Clinical practice guidelines should be written for the physician who sees patients who already have or are at high risk for osteoporosis. They should also guide the physician in distinguishing between those at high and low risk and provide general guidelines for prevention of osteoporosis for the low-risk patient. Patients at high risk may require intervention to prevent further bone loss. The guidelines should be based on the strongest evidence available and be easy to comprehend and apply. Methods to identify individuals at high risk for osteoporosis must be described. Effective interventions also should be described, as should their benefits and risks. Elderly individuals who have a poor diet and little sun exposure may be vitamin D deficient unless a supplement is given. Factors that may be deleterious to the skeleton should be avoided. Weight-bearing exercise is important throughout life. Assessment of fracture risk is important in choosing candidates for intervention, especially interventions aimed at preventing osteoporosis. Measuring bone mass at any skeletal site is the necessary initial step for most individuals; measurement at the hip may best assess the risk of hip fracture. Some risk factors independent of bone mass may also aid in patient selection. The WHO has defined osteoporosis as a bone mass at least 2.5 standard deviations (SDs) below the mean of young normal. Such individuals and those with bone mass from 1 to 2.5 SDs below the mean of young normal may also be considered for intervention. The decision will depend on assessments of the risks, the costs of treatment, the desire of the patient, and the presence of other independent risk factors. The patient with an acute fracture may require an orthopedic intervention and should receive adequate analgesia. Physical therapy is an important adjunct that aids recovery. A number of therapeutic interventions, including adequate calcium intake throughout life and an adequate vitamin D intake, are available to high-risk individuals. These interventions may be recommended generally and do not require a diagnosis of osteoporosis. Similarly, a safe weight-bearing exercise program that helps to maintain muscle strength can be recommended to older patients. Other forms of therapy include hormone replacement, bisphosphonates, and calcitonin. Vitamin D analogs and selective estrogen receptor modulators may be helpful in the future. The risks and costs of each therapy should be weighed against its benefit in slowing bone loss or increasing bone mass and reducing fractures.

Female

Time-dependent changes in biochemical bone markers and serum cholesterol in ovariectomized rats: effects of raloxifene HCl, tamoxifen, estrogen, and alendronate.

Bone loss associated with postmenopausal osteoporosis can be reduced by treatment with antiresorptive agents such as estrogen or bisphosphonates. Whereas bisphosphonates primarily affect bone loss, estrogens have an advantage of also lowering serum cholesterol levels, although they have a detrimental effect in the uterus. Recently, raloxifene HCl, a selective estrogen receptor modulator (SERM), has been shown to decrease both bone loss and cholesterol levels without the negative uterine effects. These antiresorptive agents reduce bone turnover, which can be evaluated by measuring bone turnover markers. To compare the effects of estrogen, two SERMs (raloxifene HCl and tamoxifen), and alendronate, a bisphosphonate that inhibits bone loss by an estrogen-independent pathway, on metabolic bone markers and cholesterol levels, rats were ovariectomized 2 weeks prior to 3 weeks of daily oral treatment with raloxifene HCl (3 mg/kg), ethynyl estradiol (0.1 mg/kg), tamoxifen (3 mg/kg), or alendronate (3 mg/kg). Raloxifene HCl, tamoxifen, and ethynyl estradiol reduced serum cholesterol to levels below control values within 4 days after initiation of treatment, whereas alendronate had no effect. After 3 weeks of treatment, serum cholesterol values in ethynyl estradiol treated animals, although still below the control value, had risen 6.4-fold; raloxifene HCl and tamoxifen values rose by only 1.4-1.5-fold. Therefore, compared with estrogen, SERMs may have a longer-term suppressive effect on serum cholesterol. At 4 days of treatment, ovariectomized rats had a 1.4-fold increase in serum osteocalcin level compared with controls. Ethynyl estradiol lowered this level within 1 week of treatment by 18%, with a more pronounced reduction of 34% at 3 weeks. In contrast, raloxifene HCl, tamoxifen, or alendronate had very little effect after the first week (6% to 13% reduction), although there was an 18% to 25% reduction by 3 weeks. Urinary pyridinoline levels, elevated 1.4-fold in the ovariectomized rat compared with controls 2 weeks after surgery, were reduced to control values after 2 weeks of treatment with raloxifene HCl, ethynyl estradiol, tamoxifen, or alendronate. These data support the concept that estrogen, raloxifene HCl, tamoxifen, and alendronate inhibit bone loss in the ovariectomized animal by reducing bone resorption. The results also indicate that for treatment of postmenopausal osteoporosis, raloxifene HCl may have an advantage over the other antiresorptives studied in having both non-uterotrophic and hypocholesterolemic effects in addition to its ability to inhibit bone resorption.

Alendronate

Effects of raloxifene hydrochloride on the endometrium of postmenopausal women.

OBJECTIVE: We evaluated subtle endometrial morphologic changes in postmenopausal women assigned to placebo, raloxifene hydrochloride 200 or 600 mg/day, or conjugated estrogens (Premarin 0.625 mg/day) according to a new estrogenicity scoring system. Raloxifene, a new selective estrogen receptor modulator, was not expected to stimulate the endometrium. STUDY DESIGN: Baseline and end point endometrial biopsies were performed during this double-blind, placebo-controlled 8-week study. A scoring system that was based on standard glandular and stromal morphologic criteria was used to quantitate estrogen-induced effects. Baseline, end point, and baseline-to-end point changes were analyzed for treatment differences. RESULTS: Treatment groups were similar at baseline with most women showing no estrogenic effects. At end point, statistically significant moderate and marked estrogenic effects were noted in 77% of estrogen-treated women versus 15% of placebo-treated women versus 0% of raloxifene-treated women. CONCLUSIONS: As expected, estrogen treatment stimulated postmenopausal endometrium. In contrast, raloxifene did not induce histopathologic evidence of endometrial stimulation in healthy postmenopausal women.

Biopsy

Effects of LY-117018 HCl on bone remodeling and mineral density in the oophorectomized rat.

OBJECTIVE: LY-117018 HCl is a recently developed, selective estrogen receptor modulator and an analog of raloxifene. Its mode of action on the skeleton is similar to that of estrogens, although it does not have the same side effects. The aim of the current study was to compare the effects produced by the administration of 17alpha-ethinyl estradiol (0.1 mg/kg/day) and LY-117018 HCl (1 mg/kg/day) on bone remodeling, bone mineral density, and body and uterus weight in sham-operated and oophorectomized rats (experimental model of postmenopausal osteoporosis). STUDY DESIGN: Twelve-week-old female Wistar rats were used. Treatment was given for 3 months after oophorectomy or sham operation. Bone mineral density was determined in the lumbar spine (L2, L3, and L4) and in the left femur with use of a Hologic QDR 1000 (S/N 277) densitometer. Bone remodeling was estimated with use of the formation markers osteocalcin (bone gla protein) and alkaline phosphatase and the resorption markers type I collagen carboxyterminal telopeptide and tartrate-resistant acid phosphatase. RESULTS AND CONCLUSIONS: The newly developed derivative of raloxifene, LY-117018 HCl, offsets the reduction in bone mineral density and the accompanying increase in bone remodeling markers observed in oophorectomized rats compared with control animals. 17Alpha-ethinyl estradiol also prevents the loss of bone mass attributed to oophorectomy, but this is accompanied by an increase in body mass and a greater increase in uterus weight than that observed after treatment with LY-117018 HCl.

Acid Phosphatase

A medical method of early pregnancy termination using tamoxifen and misoprostol.

A study was undertaken to determine whether ingestion of the selective estrogen receptor modulator tamoxifen followed by vaginal administration of the prostaglandin misoprostol would be an effective medical method of elective termination of early pregnancy. A clinical trial was conducted with a study group of 100 healthy women with pregnancies of 56 days gestational age or less who desired elective pregnancy termination. Each subject ingested 20 mg of tamoxifen once daily for 4 days followed 4 days later by intravaginal placement of four 200 micrograms tablets of misoprostol. If abortion did not occur within the next 24 h a second dose of 800 micrograms of misoprostol was given. The main outcome measures were incidence of complete abortion, hemoglobin levels, duration of vaginal bleeding, and incidence of side effects. Complete abortion occurred in 92 (92%, 95% CI 86.7, 97.3%) of 100 subjects. Of these 92 women, four aborted after ingesting tamoxifen without use of misoprostol, 84 within 24 h after receiving a single dose of misoprostol, one 21 days following a single dose of misoprostol, and three after a second dose of misoprostol was administered. There were six (6.0%) complete treatment failures and two (2%) incomplete abortions that required a dilatation and curettage. The mean duration of uterine bleeding was 8.1 days (range 1-34 days) and there was a median decrease in hemoglobin level of 0.50 g/dL (+2.2 to -4.7 g/dL). Vomiting occurred in 28% of subjects and diarrhea in 8%. These initial data suggest that ingestion of tamoxifen followed by intravaginal misoprostol may be an effective, easily administered, and inexpensive method to electively induce complete abortion in pregnancies of 56 days gestational age or less. Additional studies are necessary to determine whether the addition of tamoxifen increases the success rate compared with that obtained with the use of vaginally administered misoprostol by itself.

Abortifacient Agents, Nonsteroidal

Raloxifene inhibits aortic accumulation of cholesterol in ovariectomized, cholesterol-fed rabbits.

BACKGROUND: The beneficial effect of long-term hormone replacement therapy in terms of a decreased risk of cardiovascular disease is now generally accepted. Raloxifene, a selective estrogen receptor modulator, has demonstrated hypolipidemic properties while leaving the endometrium unstimulated. METHODS AND RESULTS: For our study of the effects of raloxifene on atherosclerosis, 75 rabbits were ovariectomized and treated with either raloxifene, 17beta-estradiol, or placebo; 25 rabbits were sham operated and treated with placebo. After 45 weeks, the raloxifene group had two thirds of the aortic atherosclerosis, as evaluated by the cholesterol content of the proximal inner part of the aorta, found in the placebo group (placebo, 577+/-55.1 nmol/mg protein; raloxifene, 397+/-53.6 nmol/mg protein; P<.05); the estrogen group had one third of the aortic atherosclerosis in the placebo group (estrogen, 177+/-32.1 nmol/mg protein; P<.001). The sham-operated group (473+/-59.6 nmol/mg protein) was not significantly different from placebo. These effects were only partly explained by the changes in serum lipids and lipoproteins, and treatment with both estrogen and raloxifene independently predicted the response in aorta cholesterol. Because plasma levels of total raloxifene were low relative to clinical values in postmenopausal women, dose-response data for raloxifene are required. CONCLUSIONS: Our findings indicate that raloxifene hydrochloride has a potentially important antiatherogenic effect, analogous to that observed with estrogen in this model.

Animals

Raloxifene.

Raloxifene is a selective estrogen receptor modulator which mimics the effects of estrogens on bone and blood lipid levels without stimulatory effects on the breast or uterus. Raloxifene inhibits estrogen-dependent proliferation of human breast cancer cells in vitro and development of induced mammary tumours in rats in vivo. Raloxifene inhibits bone resorption induced by estrogen deficiency in murine and human studies and lowers serum cholesterol levels. In clinical studies in postmenopausal women, raloxifene 60 mg/day for 2 years significantly increased bone mineral density compared with placebo. In comparative clinical studies, raloxifene 60 mg/day had more modest effects than conjugated estrogens 0.625 mg/day on bone resorption and formation parameters and appeared to be less effective in increasing bone mineral density. In older postmenopausal women with existing bone fractures, raloxifene 60 or 120 mg/day for 1 year produced modest increases in bone mineral density. The most common treatment-related adverse events in raloxifene recipients were hot flushes and leg cramps. The risk of venous thromboembolic events is increased during raloxifene therapy. In contrast with conjugated estrogens 0.625 mg/day, raloxifene 200 or 600 mg/day for 8 weeks or 150 mg/day for 1 year did not produce endometrial proliferation.

Animals

A practical guide to prescribing hormone replacement therapy.

Over the past 20 years there has been increasing interest in the menopause and hormone replacement therapy (HRT). More recently, postmenopausal HRT has been seen as a specific treatment for symptoms in the short term and preventative therapy in the long term. Women must be counselled regarding the risks and benefits of HRT according to the best available evidence. The patient should also be actively involved in the decision regarding HRT therapy, which should then improve patient compliance. Generally, an appropriate regimen of HRT can be formulated for the majority of patients. Progestogen should be added to therapy in women with an intact uterus in a cyclical or continuous regimen. The management of common estrogenic and progestogenic adverse effects is important in improving compliance. At present, new drugs are being developed for the management of the menopause (selective estrogen receptor modulators and phytoestrogens). Obviously, further research will be necessary to determine whether these drugs have advantages over regular HRT. By offering postmenopausal women HRT an attempt is made to optimise their physical and psychological well-being. However, HRT is not without adverse effects, the most worrying of which is the possible increase in breast cancer risk with long term use. However, with patient education efforts, treatment regimens acceptable to both patient and practitioner can be initiated; in this regard, the aim of the practitioner should be to help the menopausal woman make the decision which is the most appropriate for her.

Contraindications