Effects of arzoxifene on bone mineral density and endometrium in postmenopausal women with normal or low bone mass

Cathelicidin LL-37 improves bone metabolic balance in rats with ovariectomy-induced osteoporosis via the Wnt/beta-catenin pathway

Osteoporosis is a bone disease characterized by low bone mineral density (BMD) and impaired bone microarchitecture due to the abnormal activity of osteoclasts. Cathelicidins are antimicrobial peptides present in the lysosomes of macrophages and polymorphonuclear leukocytes. LL-37, a cathelicidin, induces various biological effects, including modulation of the immune system, angiogenesis, wound healing, cancer growth, as well as inflammation, and bone loss. A previous study reported direct involvement of LL-37 suppressing osteoclastogenesis in humans. Here, we examined the role of LL-37 in the treatment of osteoporosis using an ovariectomy (OVX) rat model. Our results showed that LL-37 significantly reduced bone loss and pathological injury in OVX rats with osteoporosis. Furthermore, we found that LL-37 significantly increased the activity of the Wnt/beta-catenin pathway in OVX rats with osteoporosis, including the increased expression of beta-catenin, Osterix (Osx), and Runt-related transcription factor 2 (Runx2), whereas XAV-939, an inhibitor of the Wnt/beta-catenin pathway, significantly blocked the effects of LL-37 on bone loss and abnormal bone metabolism. Altogether, our findings suggested that LL-37 exerted a protective role in regulating bone loss and abnormal bone metabolism in rats with osteoporosis by activating the Wnt/beta-catenin pathway.

Correlation between bone mineral density and endometrial thickness over time in women with breast cancer history

As the efficacy of chemotherapy and adjuvant endocrine therapy for breast cancer increase, the quality-of-life to cancer survivors could be more important issue in strategies of breast cancer treatment. Bone health has become more compelling in care of breast cancer survivor than ever before. This retrospective study was aimed to evaluate factors relating to the change in BMD and to ascertain the correlation between changes in BMD and EMT of women with breast cancer in follow-up. Records of 164 women who underwent surgery for breast cancer were reviewed in this study. The basal characteristics included parity, menopausal state, medication with vitamin D, bisphosphonate, selective estrogen modulator (SERM), aromatase inhibitor (AI), gonadotrophin releasing hormone agonist (GnRHa), chemotherapy, radiotherapy, cancer type including positivity of estrogen receptor, progesterone receptor and HER2, combined the other gynecologic disease or the other origin cancer. At initial and follow-up visit, all subjective were checked with BMD, endometrial thickness (EMT). The mean age was 52.1 ± 8.5 years old and overall interval between initial and follow-up visits were 17.6 ± 7.5 month in this study. The BMDs of L1-4 (1.040 ± 0.166 g/cm2 vs 1.070 ± 0.181 g/cm2, p < 0.001), femur neck (0.850 ± 0.121 g/cm2 vs 0.870 ± 0.136 g/cm2, p < 0.001), and femur total (0.902 ± 0.132 g/cm2 vs 0.915 ± 0.138 g/cm2, p < 0.001) at follow-up visit were significantly lower than those at initial visit. The change in BMDs of L1-4 (ΔBMDL1-4, r = 0.353, p < 0.001, and r = 0.228, p = 0.003), femur neck (ΔBMDNeck, r = 0.198, p = 0.011, and r = 0.282, p < 0.001), femur total (ΔBMDTotal, r = 0.294, p < 0.001, and r = 0.327, p < 0.001) had positive correlation with age and the change in EMT (ΔEMT). After age correction, ΔEMT had positive correlation with ΔBMDNeck (r = 0.245, p = 0.002) and ΔBMDTotal (r = 0.273, p < 0.001). ΔBMDL1-4 and ΔBMDNeck differed according to menopausal state (p < 0.001 and p = 0.035), bisphosphonate (p < 0.001 and p < 0.001), and GnRHa (p < 0.001 and p < 0.001). In follow-up of women with history of breast cancer, ΔEMT could be an alternative screening marker for BMD decrease.

Comparative study of DHA-enriched phosphatidylcholine and EPA-enriched phosphatidylcholine on ameliorating high bone turnover via regulation of the osteogenesis-related Wnt/β-catenin pathway in ovariectomized mice

Here, we compared the effects of marine DHA-enriched phosphatidylcholine (DHA-PC) and EPA-enriched phosphatidylcholine (EPA-PC) on high bone turnover in a model of osteoporosis induced by bilateral ovariectomy in vivo, and further investigated the possible protective mechanisms. Meanwhile, DHA-PC and EPA-PC clearly ameliorated the microstructure of the trabecular bone and accelerated bone mineral apposition rate, additionally increasing bone mineral density and biomechanical properties of the bone. Furthermore, gene and protein expression levels suggest that DHA-PC and EPA-PC inhibited overactive osteogenesis via down-regulation of the expression of the osteogenesis-related Wnt/β-catenin signaling pathway. In conclusion, DHA-PC and EPA-PC reduced excessive osteogenesis via normalization of Wnt/β-catenin expression. These results may contribute to the elucidation of the anti-osteoporotic properties of DHA-PC and EPA-PC and further develop their potential application value as a functional food.

Structure-Based Reactivity Profiles of Reactive Metabolites with Glutathione

Therapeutic agents can be transformed into reactive metabolites under the action of various metabolic enzymes in vivo and then covalently combine with biological macromolecules (such as protein or DNA), resulting in increasing toxicity. The screening of reactive metabolites in drug discovery and development stages and monitoring of biotransformation in post-market drugs has become an important research field. Generally, reactive metabolites are electrophilic and can be captured by small nucleophiles. Glutathione (GSH) is a small peptide composed of three amino acids (i.e., glutamic acid, cysteine, and glycine). It has a thiol group which can react with electrophilic groups of reactive metabolic intermediates (such as benzoquinone, N-acetyl-p-benzoquinoneimine, and Michael acceptor) to form a stable binding conjugate. This paper aims to provide a review on structure-based reactivity profiles of reactive metabolites with GSH. Furthermore, this review also reveals the relationship between drugs' molecular structures and reactive metabolic toxicity from the perspective of metabolism, giving a reference for drug design and development.

Unmasking Dipole Character of Acyl Ketene Dithioacetals via a Cascade Reaction with Arynes: Synthesis of Benzo[b]thiophenes

An unusual strategy toward novel substituted benzo[b]thiophenes has been developed. The generation of arynes in the presence of acyl ketene dithioacetals resulted in a cascade reaction involving [3 + 2] cycloaddition, and a dealkylative arylation of a thioether moiety to afford 2,3-disubstuted benzo[b]thiophenes. This route represents an expeditious approach to benzothiophenes that employs acyl ketene dithioacetals as dipoles.

Lannea acida A. Rich. (Anacardiaceae) Ethanol Extract Exhibits Estrogenic Effects and Prevents Bone Loss in an Ovariectomized Rat Model of Osteoporosis

Phytoestrogens have been shown to prevent postmenopausal osteoporosis. Lannea acida is a medicinal plant traditionally used in Cameroon to treat infertility, gynaecological complaints, and rheumatism. These uses prompted us to evaluate estrogenic activity of Lannea acida bark ethanolic extract and its antiosteoporotic potential in ovariectomized Wistar rats. In vitro, the E-screen assay was used to assess the ability of L. acida extract to induce MCF-7 cells proliferation. In vivo, a 3-day uterotrophic assay and a 12-week oral treatment in ovariectomized adult rats were carried out to evaluate the ability of L. acida extract to prevent bone mass loss. L. acida extract induced MCF-7 cell proliferation. In vivo, it significantly increased the uterine wet weight, uterine and vaginal epithelial heights, and mammary glands differentiation. At 200 mg/kg, a long-term treatment with the extract prevented body weight gain (p < 0.05) and loss of bone mass and/or density (p < 0.05) induced by ovariectomy. Also, a significant (p < 0.001) decrease of alkaline phosphatase activity was observed with 50 mg/kg. L. acida extract improved bone microarchitecture and could restore normal bone mineralization by increasing the inorganic phosphorus and calcium level in bone. These findings provide evidence that Lannea acida is a potential alternative for the prevention of postmenopausal osteoporosis.

From empirical to mechanism-based discovery of clinically useful Selective Estrogen Receptor Modulators (SERMs)

Our understanding of the molecular mechanisms underlying the pharmacological actions of estrogen receptor (ER) ligands has evolved considerably in recent years. Much of this knowledge has come from a detailed dissection of the mechanism(s) of action of the Selective Estrogen Receptor Modulators (SERMs) tamoxifen and raloxifene, drugs whose estrogen receptor (ER) agonist/antagonist properties are influenced by the cell context in which they operate. These studies have revealed that notwithstanding differences in drug pharmacokinetics, the activity of an ER ligand is determined primarily by (a) the impact that a given ligand has on the receptor conformation and (b) the ability of structurally distinct ER-ligand complexes to interact with functionally distinct coregulators. Exploitation of the established relationships between ER structure and activity has led to the development of improved SERMs with more favorable therapeutic properties and of tissue-selective estrogen complexes, drugs in which a SERM and an ER agonist are combined to yield a blended activity that results in distinct clinical profiles. Remarkably, endogenous ligands that exhibit SERM activity have also been identified. One of these ligands, 27-hydroxycholesterol (27HC), has been shown to manifest ER-dependent pathological activities in the cardiovascular system, bone and mammary gland. Whereas the physiological activity of 27HC remains to be determined, its discovery highlights how cells have adopted mechanisms to allow the same receptor ligand complex to manifest different activities in different cells, and also how these processes can be exploited for new drug development.

An overview of current and emerging SERMs

Selective estrogen receptor modulators (SERMs) are compounds that exhibit tissue-specific estrogen receptor (ER) agonist or antagonist activity, and are used for various indications, including treatment of breast cancer, osteoporosis, and menopausal symptoms. Endometrial safety has been a key differentiator between SERMs in clinical practice. For example, tamoxifen exhibits ER agonist activity in the uterus, resulting in an increased risk of endometrial hyperplasia and malignancy, whereas raloxifene and bazedoxifene have neutral effects on the uterus. Based on their efficacy and long-term safety, SERMs are increasingly being prescribed for women who cannot tolerate other treatment options and for younger women at an increased risk of fracture who may remain on therapy for long periods of time. Continuing advances in the understanding of SERM mechanisms of action and structural interactions with the ER may lead to the development of new agents and combinations of agents to provide optimal treatments to meet the varying needs of postmenopausal women. One such example is the tissue selective estrogen complex, which partners a SERM with 1 or more estrogens, with the aim of blending the desired estrogen-receptor agonist activities of estrogens on vasomotor symptoms, vulvar-vaginal atrophy, and loss of bone mass with the tissue selectivity of a SERM.

The discovery and development of selective estrogen receptor modulators (SERMs) for clinical practice

Selective estrogen receptor modulators (SERMs) are structurally different compounds that interact with intracellular estrogen receptors in target organs as estrogen receptor agonists or antagonists. These drugs have been intensively studied over the past decade and have proven to be a highly versatile group for the treatment of different conditions associated with postmenopausal women's health, including hormone responsive cancer and osteoporosis. Tamoxifen, a failed contraceptive is currently used to treat all stages of breast cancer, chemoprevention in women at high risk for breast cancer and also has beneficial effects on bone mineral density and serum lipids in postmenopausal women. Raloxifene, a failed breast cancer drug, is the only SERM approved internationally for the prevention and treatment of postmenopausal osteoporosis and vertebral fractures. However, although these SERMs have many benefits, they also have some potentially serious adverse effects, such as thromboembolic disorders and, in the case of tamoxifen, uterine cancer. These adverse effects represent a major concern given that long-term therapy is required to prevent osteoporosis or prevent and treat breast cancer. The search for the 'ideal' SERM, which would have estrogenic effects on bone and serum lipids, neutral effects on the uterus, and antiestrogenic effects on breast tissue, but none of the adverse effects associated with current therapies, is currently under way. Ospemifene, lasofoxifene, bazedoxifene and arzoxifene, which are new SERM molecules with potentially greater efficacy and potency than previous SERMs, have been investigated for use in the treatment and prevention of osteoporosis. These drugs have been shown to be comparably effective to conventional hormone replacement therapy in animal models, with potential indications for an improved safety profile. Clinical efficacy data from ongoing phase III trials are available or are awaited for each SERM so that a true understanding of the therapeutic potential of these compounds can be obtained. In this article, we describe the discovery and development of the group of medicines called SERMs. The newer SERMs in late development: ospemifene, lasofoxifene, bazedoxifene, are arzoxifene are described in detail.

Selective estrogen receptor modulator BC-1 activates antioxidant signaling pathway in vitro via formation of reactive metabolites

AIM

Benzothiophene compounds are selective estrogen receptor modulators (SERMs), which are recently found to activate antioxidant signaling. In this study the molecular mechanisms of antioxidant signaling activation by benzothiophene compound BC-1 were investigated.

METHODS

HepG2 cells were stably transfected with antioxidant response element (ARE)-luciferase reporter (HepG2-ARE cells). The expression of nuclear factor erythroid 2-related factor 2 (Nrf2) in HepG2-ARE cells was suppressed using siRNA. The metabolites of BC-1 in rat liver microsome incubation were analyzed using LC-UV and LC-MS.

RESULTS

Addition of BC-1 (5 μmol/L) in HepG2-ARE cells resulted in a 17-fold increase of ARE-luciferase activity. Pretreatment with the estrogen receptor agonist E2 (5 μmol/L) or antagonist ICI 182,780 (5 μmol/L) did not affect BC-1-induced ARE-luciferase activity. However, transfection of the cells with anti-Nrf2 siRNA suppressed this effect by 79%. Addition of BC-1 in rat microsome incubation resulted in formation of di-quinone methides and o-quinones, followed by formation of GSH conjugates. BC-1 analogues with hydrogen (BC-2) or fluorine (BC-3) at the 4' position did not form the di-quinone methides. Both BC-2 and BC-3 showed comparable estrogenic activity with BC-1, but did not induce ARE-luciferase activity in HepG2-ARE cells.

CONCLUSION

Benzothiophene compound BC-1 activates ARE signaling via reactive metabolite formation that is independent of estrogen receptors.

Arzoxifene versus raloxifene: effect on bone and safety parameters in postmenopausal women with osteoporosis

Arzoxifene increased bone mineral density and decreased bone turnover to a significantly greater extent than raloxifene. The hot flush incidence was lower with arzoxifene than raloxifene.

INTRODUCTION

To assess the effect of arzoxifene versus raloxifene on change in lumbar spine (LS) bone mineral density (BMD) in postmenopausal women with osteoporosis.

METHODS

In this 12-month study (NEXT trial), participants were randomly assigned to arzoxifene 20 mg/day (N = 158) or raloxifene 60 mg/day (N = 162). All received daily calcium and vitamin D. Change in LS BMD was assessed by DXA. Secondary objectives included assessment of femoral neck (FN) and total hip BMD, serum bone turnover markers, and safety.

RESULTS

Treatment groups were similar at baseline (mean age 63 years, mean LS BMD T-score -2.9). At 12 months, the increase in LS BMD with arzoxifene was greater than with raloxifene (+2.75% vs. +1.66%), as was FN and total hip BMD (P < 0.05). For LS and FN, this effect was also evident at 6 months. Arzoxifene reduced bone turnover to a greater extent than raloxifene at 3, 6, and 12 months (P < 0.05). The proportion of women reporting ≥ 1 adverse event did not differ between treatment groups, nor did vaginal bleeding. No cases of endometrial polyps, hyperplasia, or cancer were reported. Nasopharyngitis and bronchitis were reported more frequently with arzoxifene versus raloxifene (10.1% vs. 2.5%, and 5.1% vs. 0%, respectively) and new/worsening hot flushes were reported less frequently with arzoxifene (7.0% vs. 16.7%) (P < 0.05).

CONCLUSIONS

Arzoxifene increased BMD and suppressed bone turnover to a greater extent than raloxifene and resulted in a lower incidence of new/worsening hot flushes. Based on subsequent findings from a fracture outcome study, this difference did not translate into improved fracture efficacy.

Safety, Efficacy and Patient Acceptability of Bazedoxifene Acetate in the Management of Postmenopausal Osteoporosis

Many pharmacological agents are available for treatment of postmenopausal osteoporosis, including estrogen and the selective modulators of estrogen receptor (SERMS). Bazedoxifene is a third-generation SERM, which acts as estrogen agonist in bone and lipid metabolism and as an antagonist in the breast and endometrium. Studies demonstrated that bazedoxifene reduced significantly the risk of vertebral fractures. In a subgroup of patients at high risk (post-hoc analysis), a reduction of nonvertebral fractures risk was reported. Moreover, the combination of conjugated estrogens with bazedoxifene seems to offer an alternative to classical hormone therapy, improving the vasomotor symptoms and vaginal atrophy, without the use of a progestin. Bazedoxifene is a promising drug for the treatment and prevention of osteoporosis in postmenopausal women; however a safety concern regarding venous thromboembolic events is needed before starting treatment.

An update on selective estrogen receptor modulators for the prevention and treatment of osteoporosis

Several selective estrogen receptor modulators are in clinical development for postmenopausal osteoporosis. Bazedoxifene has shown significant reductions in vertebral and non-vertebral (in higher-risk women) fracture risk, with no evidence of breast or endometrial stimulation. Lasofoxifene has demonstrated significant reductions in vertebral and non-vertebral fracture risk, but has been associated with endometrial/uterine effects. Both selective estrogen receptor modulators were generally safe and well tolerated but have been associated with some "class effects" (e.g., hot flushes, venous thromboembolic events). A tissue selective estrogen complex partnering bazedoxifene with conjugated estrogens is under clinical investigation for the treatment of menopausal symptoms and osteoporosis prevention. Future directions in selective estrogen receptor modulator research include ospemifene and RAD 1901.

Benzothiophene carboxamide derivatives as inhibitors of Plasmodium falciparum enoyl-ACP reductase

Benzothiophene derivatives like benzothiophene sulphonamides, biphenyls, or carboxyls have been synthesized and have found wide pharmacological usage. Here we report, bromo-benzothiophene carboxamide derivatives as potent, slow tight binding inhibitors of Plasmodium enoyl-acyl carrier protein (ACP) reductase (PfENR). 3-Bromo-N-(4-fluorobenzyl)-benzo[b]thiophene-2-carboxamide (compound 6) is the most potent inhibitor with an IC50 of 115 nM for purified PfENR. The inhibition constant (Ki) of compound 6 was 18 nM with respect to the cofactor and 91 nM with respect to crotonoyl-CoA. These inhibitors showed competitive kinetics with cofactor and uncompetitive kinetics with the substrate. Thus, these compounds hold promise for the development of potent antimalarials.

New approaches to the treatment of osteoporosis

Although safe and effective agents are currently available to treat osteoporosis, fragility fractures remain a significant problem worldwide. Recent improvements in the understanding of the cellular, biochemical, and molecular pathways of bone biology have led to the development of newer agents to treat osteoporosis, which may lead to further improvements in outcomes. In this review, we summarize the most recent advances in the field, including new modes of administration of existing drug classes, various approaches to combination therapy, and drugs with novel mechanisms of action to treat osteoporosis.

Emerging drugs for the management of cancer treatment induced bone loss

AREAS COVERED IN THIS REVIEW

We focus our attention on data on the efficacy of currently available and emerging drugs for the management of cancer treatment induced bone loss (CTIBL) found in a PubMed research from 1997 till today.

IMPORTANCE OF THE FIELD

One of the most common and severe safety issues of the antihormonal therapy in both sexes is the CTIBL and the related fragility fractures. In postmenopausal women with estrogenic receptor positive breast cancer, the third-generation aromatase inhibitors (AIs) are the standard therapy. Observational retrospective studies have found that AIs treated patients had a high rate of bone loss and fracture risk (RR 1.3). Also in men with prostate cancer receiving androgen deprivation therapy, the increase in bone turnover and the consequent bone loss are very rapid and sustained significantly increasing the fracture risk.

WHAT THE READER WILL GAIN

The aim of our review is to provide the current evidences for the management of bone loss and fracture risk in this subpopulation.

TAKE HOME MESSAGE

The very high rate of bone loss and the high incidence of fractures indicate that cancer patients at risk of CTIBL need to be carefully monitored and stratified for fracture risk. Although there is a strong evidence of efficacy in prevention of bone loss and reduction of fracture risk for many drugs approved for postmenopausal osteoporosis (PMO) and male osteoporosis, for CTIBL there are actually no drugs approved for this indication.

Endometrial safety: a key hurdle for selective estrogen receptor modulators in development

Selective estrogen receptor modulators (SERMs) have the ability to provide mixed functional estrogen receptor (ER) agonist or antagonist activity, depending on the target tissue. Tamoxifen, the first SERM available for clinical use, is regarded as a highly effective agent for the prevention and treatment of breast cancer. However, tamoxifen exhibits ER agonist activity in the uterus and is associated with an increased risk of endometrial hyperplasia and malignancy. Endometrial safety has been an important consideration in the clinical development of SERMs, with improved benefit-risk profiles. Raloxifene, which is currently approved for the prevention and treatment of postmenopausal osteoporosis and for the prevention of breast cancer, seems to have neutral effects on the uterus. Promising results have been observed with the targeted development of newer and more tissue-specific SERMs, many of which are under investigation for postmenopausal osteoporosis. Of the newer SERMs in development, lasofoxifene has been shown to reduce fracture risk and decrease the incidence of breast cancer but has been associated with an increased incidence of vaginal bleeding, endometrial thickening, and endometrial polyps. Lasofoxifene and ospemifene have shown beneficial effects on the vaginal epithelium. Phase 3 clinical data have shown that bazedoxifene is effective in preventing and treating postmenopausal osteoporosis, without adverse effects on the endometrium or breast. Arzoxifene has been evaluated in phase 3 trials for postmenopausal osteoporosis and has been studied for the treatment of uterine malignancies but is no longer in clinical development. Further investigation of newer SERMs is warranted to more clearly define the endometrial safety of these agents.

Update on estrogens and the skeleton

CONTEXT

The very clinical trial, the Women's Health Initiative, which definitely established the antifracture efficacy of estrogen therapy, led to the demise of estrogen treatment as a viable, long-term option for prevention of bone loss in postmenopausal women due to the well-publicized adverse effects of estrogen plus progestin therapy on a number of nonskeletal endpoints. Given the diminishing clinical use of estrogen, it is logical to question whether estrogen regulation of bone remains a relevant issue at a clinical or basic research level.

EVIDENCE ACQUISITION

Findings of this update are based on a PubMed search and the author's knowledge of the field.

EVIDENCE SYNTHESIS

Basic and clinical studies on the mechanisms of estrogen effects on bone will continue to provide potential novel drug targets for the prevention and treatment of osteoporosis. At a clinical level, it is clear that even the low levels of estrogen present in postmenopausal women have a significant impact on bone turnover, leading to a more aggressive approach to prevent bone loss in patients with breast cancer on aromatase inhibitors. Conversely, increasing these low estrogen levels with small doses of estrogen may have beneficial skeletal effects in postmenopausal women without adverse effects on reproductive tissues. Finally, the search continues for new selective estrogen receptor modulators with beneficial effects on bone and other tissues.

CONCLUSIONS

Even in the post-WHI era, basic and clinical investigation on estrogen and bone will continue to yield important insights that not only expand our knowledge at a basic level but also impact the health of our aging population.

Developing drugs to treat osteoporosis: lessons learned?

BACKGROUND

Selective estrogen-receptor modulators (SERMs) are drugs that act as estrogen receptor agonists or antagonists depending on the target tissue. Theoretically this class of agents would be an ideal substitute for hormone replacement therapy (HRT), if their effects on the skeleton matched those of estrogen while their actions on other tissues were either neutral or beneficial.

OBJECTIVE

To evaluate a Phase III trial of a new SERM, arzoxefine, for prevention of osteoporosis in younger postmenopausal women.

METHODS/RESULTS

Arzoxifene induced modest but significant increases in bone mineral density versus a control group during 2 years of therapy, with minor adverse events. However, fracture efficacy and other patient-specific outcomes were not evaluated.

CONCLUSION

Despite a positive study of surrogate end points (bone density and biochemical markers of bone turnover), arzoxifene was withdrawn from further FDA evaluation, principally because of long-term side effects and lack of non-vertebral fracture efficacy in the companion Phase III fracture study. Each SERM has a unique profile on bone and other tissues. Regulatory approval of this class of agents may remain problematic for the immediate future.

SERMs in the prevention and treatment of postmenopausal osteoporosis: an update

Selective estrogen receptor modulators (SERMs) have the ability to bind the estrogen receptor (ER) and are known to confer ER agonist or antagonist effects depending on the target tissue. A number of newer SERMs, including bazedoxifene, lasofoxifene and ospemifene, are currently under clinical development for the prevention and treatment of postmenopausal osteoporosis and for other indications. Although the possibility of developing a single agent that has all of the desired characteristics of an ideal SERM seems to be unlikely, progress in the clinical development of SERMs targeted to the ER suggests that these newer compounds may have attributes that represent an improvement relative to existing SERMs. A new approach to menopausal therapy is the tissue selective estrogen complex or the pairing of a selective estrogen receptor modulator with estrogens. Further investigation will help to clarify relative benefits/risks of novel SERMs in development within specific indications.