Lasofoxifene and cardiovascular events in postmenopausal women with osteoporosis: Five-year results from the Postmenopausal Evaluation and Risk Reduction with Lasofoxifene (PEARL) trial

New potential selective estrogen receptor modulators in traditional Chinese medicine for treating menopausal syndrome

Women go through several predictable conditions and symptoms during menopause that are caused by age, changes in sex hormone levels, and other factors. Conventional menopause hormone therapy has raised serious concerns about the increased risks of cancers, blood clots, depression, etc. Selective estrogen receptor modulators (SERMs) that can be both agonists and antagonists of estrogen receptors in a tissue-specific manner are being developed to reduce the health concerns associated with menopause hormone therapy. Here, we have searched the Chinese national traditional Chinese medicine (TCM) patent database to identify potential SERM-like compounds with reduced health risks. TCM has been widely used for treating complex symptoms associated with menopause syndrome and thus can be a particularly rich source for pharmaceutical alternatives with SERM properties. After extensive literature review and molecular simulation, we conclude that protopanaxatriol, paeoniflorin, astragalin, catalpol, and hyperoside among others may be particularly promising as SERM-like compounds in treating the menopausal syndrome. Compounds in TCM hold promise in yielding comparable outcomes to hormone therapy but with reduced associated risks, thus presenting promising avenues for their clinical applications.

Sex and sex steroids as determinants of cardiovascular risk

There are considerable sex differences regarding the risk of cardiovascular disease (CVD), including arterial hypertension, coronary artery disease (CAD) and stroke, as well as chronic renal disease. Women are largely protected from these conditions prior to menopause, and the risk increases following cessation of endogenous estrogen production or after surgical menopause. Cardiovascular diseases in women generally begin to occur at a later age than in men (on average with a delay of 10 years). Cessation of estrogen production also impacts metabolism, increasing the risk of developing obesity and diabetes. In middle-aged individuals, hypertension develops earlier and faster in women than in men, and smoking increases cardiovascular risk to a greater degree in women than it does in men. It is not only estrogen that affects female cardiovascular health and plays a protective role until menopause: other sex hormones such as progesterone and androgen hormones generate a complex balance that differentiates heart and blood vessel function in women compared to men. Estrogens improve vasodilation of epicardial coronary arteries and the coronary microvasculature by augmenting the release of vasodilating factors such as nitric oxide and prostacyclin, which are mechanisms of coronary vasodilatation that are more pronounced in women compared to men. Estrogens are also powerful inhibitors of inflammation, which in part explains their protective effects on CVD and chronic renal disease. Emerging evidence suggests that sex chromosomes also play a significant role in shaping cardiovascular risk. The cardiovascular protection conferred by endogenous estrogens may be extended by hormone therapy, especially using bioidentical hormones and starting treatment early after menopause.

Lasofoxifene versus fulvestrant for ER+/HER2- metastatic breast cancer with an ESR1 mutation: results from the randomized, phase II ELAINE 1 trial

BACKGROUND

Acquired estrogen receptor alpha (ER/ESR1) mutations commonly cause endocrine resistance in ER+ metastatic breast cancer (mBC). Lasofoxifene, a novel selective ER modulator, stabilizes an antagonist conformation of wild-type and ESR1-mutated ER-ligand binding domains, and has antitumor activity in ESR1-mutated xenografts.

PATIENTS AND METHODS

In this open-label, randomized, phase II, multicenter, ELAINE 1 study (NCT03781063), we randomized women with ESR1-mutated, ER+/human epidermal growth factor receptor 2 negative (HER2-) mBC that had progressed on an aromatase inhibitor (AI) plus a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) to oral lasofoxifene 5 mg daily or IM fulvestrant 500 mg (days 1, 15, and 29, and then every 4 weeks) until disease progression/toxicity. The primary endpoint was progression-free survival (PFS); secondary endpoints were safety/tolerability.

RESULTS

A total of 103 patients received lasofoxifene (n = 52) or fulvestrant (n = 51). The most current efficacy analysis showed that lasofoxifene did not significantly prolong median PFS compared with fulvestrant: 24.2 weeks (∼5.6 months) versus 16.2 weeks (∼3.7 months; P = 0.138); hazard ratio 0.699 (95% confidence interval 0.434-1.125). However, PFS and other clinical endpoints numerically favored lasofoxifene: clinical benefit rate (36.5% versus 21.6%; P = 0.117), objective response rate [13.2% (including a complete response in one lasofoxifene-treated patient) versus 2.9%; P = 0.124], and 6-month (53.4% versus 37.9%) and 12-month (30.7% versus 14.1%) PFS rates. Most common treatment-emergent adverse events with lasofoxifene were nausea, fatigue, arthralgia, and hot flushes. One death occurred in the fulvestrant arm. Circulating tumor DNA ESR1 mutant allele fraction (MAF) decreased from baseline to week 8 in 82.9% of evaluable lasofoxifene-treated versus 61.5% of fulvestrant-treated patients.

CONCLUSIONS

Lasofoxifene demonstrated encouraging antitumor activity versus fulvestrant and was well tolerated in patients with ESR1-mutated, endocrine-resistant mBC following progression on AI plus CDK4/6i. Consistent with target engagement, lasofoxifene reduced ESR1 MAF, and to a greater extent than fulvestrant. Lasofoxifene may be a promising targeted treatment for patients with ESR1-mutated mBC and warrants further investigation.

Open-label, phase II, multicenter study of lasofoxifene plus abemaciclib for treating women with metastatic ER+/HER2- breast cancer and an ESR1 mutation after disease progression on prior therapies: ELAINE 2

BACKGROUND

Acquired ESR1 mutations in estrogen receptor-positive (ER+) metastatic breast cancer (mBC) drive treatment resistance and tumor progression; new treatment strategies are needed. Lasofoxifene, a next-generation, oral, endocrine therapy and tissue-specific ER antagonist, provided preclinical antitumor activity, alone or combined with a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) in ESR1-mutated mBC.

PATIENTS AND METHODS

In the open-label, phase II, ELAINE 2 trial (NCT04432454), women with ESR1-mutated, ER+/human epidermal growth factor receptor 2-negative (HER2-) mBC who progressed on prior therapies (including CDK4/6i) received lasofoxifene 5 mg/day and abemaciclib 150 mg b.i.d until disease progression/toxicity. The primary endpoint was safety/tolerability. Secondary endpoints included progression-free survival (PFS), clinical benefit rate (CBR), and objective response rate (ORR).

RESULTS

Twenty-nine women (median age 60 years) participated; all but one were previously treated with a CDK4/6i (median duration 2 years). The lasofoxifene-abemaciclib combination was well tolerated with primarily grade 1/2 treatment-emergent adverse events (TEAEs), most commonly diarrhea, nausea, fatigue, and vomiting. One patient (with no prior CDK4/6i) discontinued treatment due to grade 2 diarrhea. No deaths occurred during the study. Median PFS was 56.0 weeks [95% confidence interval (CI) 31.9 weeks-not estimable; ∼13 months]; PFS rates at 6, 12, and 18 months were 76.1%, 56.1%, and 38.8%, respectively. CBR at 24 weeks was 65.5% (95% CI 47.3% to 80.1%). In 18 patients with measurable lesions, ORR was 55.6% (95% CI 33.7% to 75.4%). ESR1-mutant circulating tumor DNA (ctDNA) allele fraction decreased from baseline to week 4 in 21/26 (80.8%) patients.

CONCLUSIONS

Lasofoxifene plus abemaciclib had an acceptable safety profile, was well tolerated, and exhibited meaningful antitumor activity in women with ESR1-mutated, ER+/HER2- mBC after disease progression on prior CDK4/6i. Observed decreases in ESR1-mutant ctDNA with lasofoxifene concordant with clinical response suggest target engagement. If the ELAINE 2 findings are confirmed in the initiated, phase III, ELAINE 3 trial, these data could be practice-changing and help address a critical unmet need.

European Stroke Organisation guidelines on stroke in women: Management of menopause, pregnancy and postpartum

Pregnancy, postpartum and menopause are regarded as periods women are more vulnerable to ischaemic events. There are conflicting results regarding stroke risk and hormone replacement therapy (HRT) during menopause. Stroke in pregnancy is generally increasing with serious consequences for mother and child; therefore, recommendations for acute treatment with intravenous thrombolysis (IVT) and/or mechanical thrombectomy (MT) are needed. The aim of this guideline is to support and guide clinicians in treatment decisions in stroke in women. Following the "Grading of Recommendations and Assessment, Development and Evaluation (GRADE)" approach, the guidelines were developed according to the European Stroke Organisation (ESO) Standard Operating Procedure. Systematic reviews and metanalyses were performed. Based on available evidence, recommendations were provided. Where there was a lack of evidence, an expert consensus statement was given. Low quality of evidence was found to suggest against the use of HRT to reduce the risk of stroke (ischaemic and haemorrhagic) in postmenopausal women. No data was available on the outcome of women with stroke when treated with HRT. No sufficient evidence was found to provide recommendations for treatment with IVT or MT during pregnancy, postpartum and menstruation. The majority of members suggested that pregnant women can be treated with IVT after assessing the benefit/risk profile on an individual basis, all members suggested treatment with IVT during postpartum and menstruation. All members suggested treatment with MT during pregnancy. The guidelines highlight the need to identify evidence for stroke prevention and acute treatment in women in more vulnerable periods of their lifetime to generate reliable data for future guidelines.

Assessment of Cardiovascular Safety of Anti-Osteoporosis Drugs

The incidence of osteoporosis and cardiovascular disease increases with age, and there are potentially shared mechanistic associations between the two conditions. It is therefore highly relevant to understand the cardiovascular implications of osteoporosis medications. These are presented in this narrative review. Calcium supplementation could theoretically cause atheroma formation via calcium deposition, and in one study was found to be associated with myocardial infarction, but this has not been replicated. Vitamin D supplementation has been extensively investigated for cardiac benefit, but no consistent effect has been found. Despite findings in the early 21st century that menopausal hormone therapy was associated with coronary artery disease and venous thromboembolism (VTE), this therapy is now thought to be potentially safe (from a cardiac perspective) if started within the first 10 years of the menopause. Selective estrogen receptor modulators (SERMs) are associated with increased risk of VTE and may be related to fatal strokes (a subset of total strokes). Bisphosphonates could theoretically provide protection against atheroma. However, data from randomised trials and observational studies have neither robustly supported this nor consistently demonstrated the potential association with atrial fibrillation. Denosumab does not appear to be associated with cardiovascular disease and, although parathyroid hormone analogues are associated with palpitations and dizziness, no association with a defined cardiovascular pathology has been demonstrated. Finally, romosozumab has been shown to have a possible cardiovascular signal, and therefore post-market surveillance of this therapy will be vital.

Selective estrogen receptor modulator lasofoxifene suppresses spondyloarthritis manifestation and affects characteristics of gut microbiota in zymosan-induced SKG mice

Ankylosing spondylitis is a male-predominant disease and previous study revealed that estrogens have an anti-inflammatory effect on the spondyloarthritis (SpA) manifestations in zymosan-induced SKG mice. This study aimed to evaluate the effect of selective estrogen receptor modulator (SERM) lasofoxifene (Laso) on disease activity of SpA. Mice were randomized into zymosan-treated, zymosan + 17β-estradiol (E2)-treated, and zymosan + Laso-treated groups. Arthritis was assessed by ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) small-animal positron emission tomography/computed tomography and bone mineral density (BMD) was measured. Fecal samples were collected and 16S ribosomal RNA gene sequencing was used to determine gut microbiota differences. Both zymosan + E2-treated mice and zymosan + Laso-treated mice showed lower arthritis clinical scores and lower ¹⁸F-FDG uptake than zymosan-treated mice. BMD was significantly higher in zymosan + E2-treated mice and zymosan + Laso-treated mice than zymosan-treated mice, respectively. Fecal calprotectin levels were significantly elevated at 8 weeks after zymosan injection in zymosan-treated mice, but it was not significantly changed in zymosan + E2-treated mice and zymosan + Laso-treated mice. Gut microbiota diversity of zymosan-treated mice was significantly different from zymosan + E2-treated mice and zymosan + Laso-treated mice, respectively. There was no significant difference in gut microbiota diversity between zymosan + E2-treated mice and zymosan + Laso -treated mice. Laso inhibited joint inflammation and enhanced BMD in SKG mice, a model of SpA. Laso also affected the composition and biodiversity of gut microbiota. This study provides new knowledge regarding that selected SpA patients could benefit from SERM treatment.

Selective Estrogen Receptor Modulators: A Potential Option For Non-Binary Gender-Affirming Hormonal Care?

Gender dysphoria describes the distress associated with having a gender identity that differs from one's birth-assigned sex. To relieve this distress, transgender, and gender diverse (henceforth, trans) individuals commonly undergo medical transition involving hormonal treatments. Current hormonal treatment guidelines cater almost exclusively for those who wish to transition from male to female or vice versa. In contrast, there is a dearth of hormonal options for those trans individuals who identify as non-binary and seek an androgynous appearance that is neither overtly male nor female. Though prolonged puberty suppression with gonadotrophin releasing hormone agonists (GnRHa) could in theory be gender-affirming by preventing the development of unwanted secondary sex characteristics, this treatment option would be limited to pre- or peri-pubertal adolescents and likely have harmful effects. Here, we discuss the theoretical use of Selective Estrogen Receptor Modulators (SERMs) for non-binary people assigned male at birth (AMAB) who are seeking an androgynous appearance through partial feminization without breast growth. Given their unique range of pharmacodynamic effects, SERMs may represent a potential gender-affirming treatment for this population, but there is a lack of knowledge regarding their use and potentially adverse effects in this context.

Controversies Regarding Postmenopausal Hormone Replacement Therapy for Primary Cardiovascular Disease Prevention in Women

The debate over the safety and benefit of hormone replacement therapy (HRT) in postmenopausal women for primary prevention of cardiovascular disease (CVD) has been ongoing for the past several decades. Observational trials in the 1980s suggested a benefit of HRT for primary CVD prevention. However, randomized controlled trials in the 1990s suggested potential harm. Because of these discrepancies, recommendations from authorities on the usage of postmenopausal HRT have fluctuated. Many believed that the timing of HRT initiation relative to the onset of menopause, also known as the "timing hypothesis," was the factor that could explain the differences among these studies. Some recent investigations have concluded that HRT initiated in postmenopausal women near the onset of menopause confers a cardioprotective benefit, while others simply showed that HRT does not cause harm. Research has expanded to evaluate alternative doses, preparations, routes, and formulations, including selective estrogen receptor modulators, to demonstrate their suitability for this purpose. This article is a review of the major research studies of HRT in postmenopausal women with respect to its safety and efficacy for the primary prevention of CVD.

Beyond estrogen: advances in tissue selective estrogen complexes and selective estrogen receptor modulators

Selective estrogen receptor modulators (SERMs) are synthetic non-steroidal agents which have variable estrogen agonist and antagonist activities in different target tissues. Tamoxifen is an anti-estrogen in the breast used for treatment and prevention of breast cancer, with estrogen agonist activity in the uterus. Raloxifene prevents and treats osteoporosis and prevents breast cancer, and can be safely combined with vaginal but not systemic estrogen. The tissue selective estrogen complex combines conjugated equine estrogens (CEE) with the SERM bazedoxifene (BZA). The five Selective Estrogen Menopause and Response to Therapy studies, with up to 2 years of data, demonstrated that CEE/BZA 0.45 mg/BZA 20 mg improved vasomotor symptoms and vulvovaginal atrophy, prevented bone loss, and was neutral on breast tenderness, breast density, with breast cancer incidence similar to placebo. Protection against estrogen-induced endometrial hyperplasia and cancer was found, with similar amenorrhea rates to placebo. Ospemifene is approved to treat dyspareunia, with potential benefits on bone and the breast, while lasofoxifene is being developed to treat resistant estrogen receptor-positive breast cancer in women. Estetrol is an estrogen synthesized exclusively during pregnancy by the human fetal liver and initially considered a weak estrogen, but it appears to have dual weak estrogenic/anti-estrogenic features.

Melatonin: Another avenue for treating osteoporosis?

Melatonin is a signal molecule that modulates the biological circadian rhythms of vertebrates. Melatonin deficiency is thought to be associated with several disorders, including insomnia, cancer, and cardiovascular and neurodegenerative diseases. Accumulating evidence has also indicated that melatonin may be involved in the homeostasis of bone metabolism. Age-related reductions in melatonin are considered to be critical factors in bone loss and osteoporosis with aging. Thus, serum melatonin levels might serve as a biomarker for the early detection and prevention of osteoporosis. Compared to conventional antiosteoporosis medicines, which primarily inhibit bone loss, melatonin both suppresses bone loss and promotes new bone formation. Mechanistically, by activating melatonin receptor 2 (MT2), melatonin upregulates the gene expression of alkaline phosphatase (ALP), bone morphogenetic protein 2 (BMP2), BMP6, osteocalcin, and osteoprotegerin to promote osteogenesis while inhibiting the receptor activator of NF-kB ligand (RANKL) pathway to suppress osteolysis. In view of the distinct actions of melatonin on bone metabolism, we hypothesize that melatonin may be a novel remedy for the prevention and clinical treatment of osteoporosis.

Development of concise two-step catalytic approach towards lasofoxifene precursor nafoxidine

We have elaborated a two-step catalytic approach to nafoxidine, a key precursor to lasofoxifene. Firstly, an efficient α-arylation of 6-methoxy-3,4-dihydronaphthalen-1(2H)-one with chlorobenzene was developed, which operates at low 0.1 mol% Pd-132 catalyst loading in the presence of 1.9 equivalents of sodium tert-butoxide at 60 °C in 1,4-dioxane and provides 6-methoxy-2-phenyl-3,4-dihydronaphthalen-1(2H)-one in 90% yield. Secondly, we have demonstrated that 6-methoxy-2-phenyl-3,4-dihydronaphthalen-1(2H)-one can be converted to nafoxidine in 61% yield via CeCl₃ promoted reaction with (4-(2-(pyrrolidin-1-yl)ethoxy)phenyl)lithium, which is formed in-situ from the corresponding arylbromide precursor and n-butyllithium. Altogether, the shortest two-step approach to nafoxidine from simple tetralone commodity starting material has been developed with overall 55% yield. The developed synthetic approach to nafoxidine has several beneficial aspects over the one used in the synthetic route primarily developed for the preparation of lasofoxifene.

Role of GPER in estrogen-dependent nitric oxide formation and vasodilation

Estrogens are potent regulators of vasomotor tone, yet underlying receptor- and ligand-specific signaling pathways remain poorly characterized. The primary physiological estrogen 17β-estradiol (E2), a non-selective agonist of classical nuclear estrogen receptors (ERα and ERβ) as well as the G protein-coupled estrogen receptor (GPER), stimulates formation of the vasodilator nitric oxide (NO) in endothelial cells. Here, we studied the contribution of GPER signaling in E2-dependent activation of endothelial NO formation and subsequent vasodilation. Employing E2 and the GPER-selective agonist G-1, we investigated eNOS phosphorylation and NO formation in human endothelial cells, and endothelium-dependent vasodilation in the aortae of wild-type and Gper-deficient mice. Both E2 and G-1 induced phosphorylation of eNOS at the activation site Ser1177 to similar extents. Endothelial NO production to E2 was comparable to that of G-1, and was substantially reduced after pharmacological inhibition of GPER. Similarly, the clinically used ER-targeting drugs 4OH-tamoxifen, raloxifene, and ICI182,780 (faslodex, fulvestrant™) induced NO formation in part via GPER. We identified c-Src, EGFR, PI3K and ERK signaling pathways to be involved in GPER-dependent NO formation. In line with activation of NO formation in cells, E2 and G-1 induced equally potent vasodilation in the aorta of wild-type mice. Gper deletion completely abrogated the vasodilator response to G-1, while reducing the response to E2 by ∼50%. These findings indicate that a substantial portion of E2-induced endothelium-dependent vasodilation and NO formation is mediated by GPER. Thus, selective targeting of vascular GPER may be a suitable approach to activate the endothelial NO pathway, possibly leading to reduced vasomotor tone and inhibition of atherosclerotic vascular disease.

Not lost in translation: Emerging clinical importance of the G protein-coupled estrogen receptor GPER

It has been 20years that the G protein-coupled estrogen receptor (GPER) was cloned as the orphan receptor GPR30 from multiple cellular sources, including vascular endothelial cells. Here, I will provide an overview of estrogen biology and the historical background leading to the discovery of rapid vascular estrogen signaling. I will also review the recent advances in the understanding of the mechanisms underlying GPER function, its role in physiology and disease, some of the currently available GPER-targeting drugs approved for clinical use such as SERMs (selective estrogen receptor modulators) and SERDs (selective estrogen receptor downregulators). Many of currently used drugs such as tamoxifen, raloxifene, or faslodex™/fulvestrant were discovered targeting GPER many years after they had been introduced to the clinics for entirely different purposes. This has important implications for the clinical use of these drugs and their modes of action, which I have termed 'reverse translational medicine'. In addition, environmental pollutants known as 'endocrine disruptors' have been found to bind to GPER. This article also discusses recent evidence in these areas as well as opportunities in translational clinical medicine and GPER research, including medical genetics, personalized medicine, prevention, and its theranostic use.

Estrogens and Coronary Artery Disease: New Clinical Perspectives

In premenopausal women, endogenous estrogens are associated with reduced prevalence of arterial hypertension, coronary artery disease, myocardial infarction, and stroke. Clinical trials conducted in the 1990s such as HERS, WHI, and WISDOM have shown that postmenopausal treatment with horse hormone mixtures (so-called conjugated equine estrogens) and synthetic progestins adversely affects female cardiovascular health. Our understanding of rapid (nongenomic) and chronic (genomic) estrogen signaling has since advanced considerably, including identification of a new G protein-coupled estrogen receptor (GPER), which like the "classical" receptors ERα and ERβ is highly abundant in the cardiovascular system. Here, we discuss the role of estrogen receptors in the pathogenesis of coronary artery disease and review natural and synthetic ligands of estrogen receptors as well as their effects in physiology, on cardiovascular risk factors, and atherosclerotic vascular disease. Data from preclinical and clinical studies using nonselective compounds activating GPER, which include selective estrogen receptor modulators such as tamoxifen or raloxifene, selective estrogen receptor downregulators such as Faslodex™ (fulvestrant/ICI 182,780), vitamin B3 (niacin), green tea catechins, and soy flavonoids such as genistein or resveratrol, strongly suggest that activation of GPER may afford therapeutic benefit for primary and secondary prevention in patients with or at risk for coronary artery disease. Evidence from preclinical studies suggest similar efficacy profiles for selective small molecule GPER agonists such as G-1 which are devoid of uterotrophic activity. Further clinical research in this area is warranted to provide opportunities for future cardiovascular drug development.

Clinical effects of selective estrogen receptor modulators on vulvar and vaginal atrophy

OBJECTIVE

Vaginal estrogen therapy at the lowest effective dose is generally recommended for the treatment of vulvar and vaginal atrophy (VVA), but not all women are candidates. Selective estrogen receptor modulators (SERMs) aim to elicit specific positive effects on targeted tissues with neutral or minimal negative effects on other tissues. This review compares the vaginal effects of currently available and investigational SERMs.

METHODS

Relevant English-language articles published between 1980 and 2012 were identified through the PubMed database (search string "[Selective Estrogen Receptor Modulator OR SERM] AND [Vulvar OR Vaginal] AND Atrophy"), article reference lists, and EMBASE searches for individual SERMs. Both authors reviewed all articles, which formed the basis of this narrative literature review.

RESULTS

Activity profiles of SERMs in various tissues are distinct. Tamoxifen and arzoxifene have no specific positive vaginal effects but have reported variable or adverse gynecologic effects. Raloxifene does not improve VVA but can be used safely in combination with vaginal estrogen. Bazedoxifene has no demonstrated efficacy for VVA but, in combination with oral conjugated equine estrogens, improves the signs and symptoms of VVA. SERMs with positive vaginal effects (such as improvement in the vaginal maturation index, reduced vaginal pH, and improvement in the signs and symptoms of VVA) on postmenopausal symptomatic women include lasofoxifene (clinical development on hold) and ospemifene, which was recently approved for the treatment of VVA-related dyspareunia, with a class effect warning of potential venous thrombosis risk.

CONCLUSIONS

SERMs that specifically target the pathophysiology underlying VVA may provide an alternative to vaginal or systemic estrogen therapy.

Selective estrogen receptor modulators (SERMs): a review of clinical data

SERMs represent a diverse group of molecules with varying levels of estrogenic agonist and antagonist activity in target tissues. SERMs have a long regulatory approval history and have been studied for a variety of therapeutic indications. The clinical effects of SERMs have been evaluated in a large number of phase 3 clinical trials. Many of the available SERMs have proved to be effective as chemo-preventive agents and treatments for breast cancer and a number are useful for the prevention and treatment of osteoporosis. The endometrial effect of SERMs has been a key differentiator in clinical practice and a major hurdle for regulatory approval. The effect of SERMs in the vagina also represents a major distinction among different SERMs. This review summarized key clinical finding of SERMs in different target tissues.

Use of SERMs for treatment in postmenopausal women

Selective estrogen receptor modulators (SERMs) are synthetic non-steroidal agents which have varying estrogen agonist and antagonist activities in different tissues, most likely due to the receptor conformation changes associated with that SERM's binding and the subsequent effect on transcription. Clinical trials aim to differentiate amongst SERMs on selected target tissues for use in postmenopausal women including effects on breast, bone, cardiovascular venous thrombosis risk, endometrium, vagina, vasomotor symptoms, and brain. This paper describes differences in clinical effects on selected target tissues of SERMs that are approved, discontinued or in development. FDA approved SERMs include tamoxifen and toremifene used for prevention and treatment of breast cancer, raloxifene approved for prevention and treatment of osteoporosis and prevention of invasive breast cancer, and ospemifene approved for treatment of dyspareunia from menopausal vaginal atrophy. The FDA approved first tissue selective estrogen complex (TSEC) a pairing of conjugated equine estrogens with the SERM, bazedoxifene. This pairing reduces the risk of endometrial hyperplasia that can occur with the estrogenic component of the TSEC without the need for a progestogen in women with a uterus. It also allows for the estrogenic benefits on relief of hot flashes and prevention of bone loss without stimulating the breast or the endometrium. In clinical practice, the tissue-selective actions of SERMs, alone or paired with estrogens, allow for individualization in meeting the treatment needs of postmenopausal women by providing targeted tissue effects. This article is part of a Special Issue entitled 'Menopause'.

Use of Pharmacologic Interventions for Breast Cancer Risk Reduction: American Society of Clinical Oncology Clinical Practice Guideline

Purpose

To update the 2009 American Society of Clinical Oncology guideline on pharmacologic interventions for breast cancer (BC) risk reduction.

Methods

A systematic review of randomized controlled trials and meta-analyses published from June 2007 through June 2012 was completed using MEDLINE and Cochrane Collaboration Library. Primary outcome of interest was BC incidence (invasive and noninvasive). Secondary outcomes included BC mortality, adverse events, and net health benefits. Guideline recommendations were revised based on an Update Committee's review of the literature.

Results

Nineteen articles met the selection criteria. Six chemoprevention agents were identified: tamoxifen, raloxifene, arzoxifene, lasofoxifene, exemestane, and anastrozole.

Recommendations

In women at increased risk of BC age ≥ 35 years, tamoxifen (20 mg per day for 5 years) should be discussed as an option to reduce the risk of estrogen receptor (ER) –positive BC. In postmenopausal women, raloxifene (60 mg per day for 5 years) and exemestane (25 mg per day for 5 years) should also be discussed as options for BC risk reduction. Those at increased BC risk are defined as individuals with a 5-year projected absolute risk of BC ≥ 1.66% (based on the National Cancer Institute BC Risk Assessment Tool or an equivalent measure) or women diagnosed with lobular carcinoma in situ. Use of other selective ER modulators or other aromatase inhibitors to lower BC risk is not recommended outside of a clinical trial. Health care providers are encouraged to discuss the option of chemoprevention among women at increased BC risk. The discussion should include the specific risks and benefits associated with each chemopreventive agent.

Cholesterol and atherosclerosis: modulation by oestrogen

PURPOSE OF REVIEW

Oestrogens are important modulators of lipid metabolism, inflammation and vascular homeostasis. Endogenous oestrogens contribute to the low prevalence of atherosclerotic vascular disease in premenopausal women with intact ovarian function, and cessation of oestrogen production following menopause increases cardiovascular risk. Orally administered oestrogens such as postmenopausal hormone therapy increase HDL and reduce LDL cholesterol levels, and they increase triglyceride levels. Current guidelines do not recommend postmenopausal hormone therapy for cardiovascular prevention.

RECENT FINDINGS

Recent clinical studies have suggested potential benefits of natural oestrogen or selective oestrogen receptor modulators on cardiovascular outcomes, effects that are associated with lipid profile improvements. In contrast to earlier studies such as the Women's Health Initiative, the Heart and Estrogen/Progestin Replacement Study or the Estrogen Replacement and Atherosclerosis trial, in which investigators used hormone mixtures derived from horse urine (misleadingly named 'conjugated oestrogens' with unknown activity on oestrogen receptors), triphasic oestrogen therapy started early after menopause as primary prevention study protocol improved outcome. New studies suggest therapeutic potential of natural oestrogens and certain selective oestrogen receptor modulators to reduce coronary artery disease risk in postmenopausal women.

SUMMARY

Endogenous oestrogens are important regulators of lipid metabolism and inhibit inflammation, vascular cell growth and plaque progression in premenopausal women. The recent trials warrant further studies, which should also determine how much of the potential benefits are due to improvements of lipid metabolism.

An update on menopausal hormone replacement therapy in women and cardiovascular disease

PURPOSE OF REVIEW

This review presents the available evidence for effects of menopausal hormone replacement therapy (MHT), more specifically estrogen, and selective estrogen receptor modulators on the cardiovascular system with a focus on randomized controlled trials (RCTs) published since 2010.

RECENT FINDINGS

In contrast to early observational studies, the Women's Health Initiative, the largest randomized controlled trial of MHT in generally healthy women, suggested harmful cardiovascular effects. Subsequent subanalyses of the Women's Health Initiative and other studies suggest the cardiovascular effects of MHT may vary by age and time since menopause, giving rise to a 'timing hypothesis'. Recent trials have looked at this issue by evaluating surrogate markers of cardiovascular disease (CVD) or CVD events adjudicated as secondary outcomes in RCTs and show a reduction in events with MHT.

SUMMARY

Athough the data overall do not support the use of MHT or selective estrogen receptor modulator for primary prevention of CVD, evidence is accumulating that careful use of MHT for perimenopausal symptoms may not carry CVD harm. This review highlights some of the strengths and weaknesses of these recent reports. Ongoing studies of MHT will shed more light on the interaction between age or time after menopause and the vascular effects of MHT.

The evolution of selective estrogen receptor modulators in osteoporosis therapy

Selective estrogen receptor modulators (SERMs), which exhibit estrogen receptor agonist or antagonist activity based on the target tissue, have evolved through multiple generations for the prevention and/or treatment of postmenopausal osteoporosis. An ideal SERM would protect bone without stimulating the breast or endometrium. Raloxifene, lasofoxifene, and bazedoxifene have demonstrated unique preclinical profiles. Raloxifene, lasofoxifene, and bazedoxifene have shown significant reduction in the risk of vertebral fracture and improvement in bone mineral density versus placebo in postmenopausal women with osteoporosis. Raloxifene has been shown to reduce the risk of non-vertebral fractures in women with severe prevalent fractures at baseline. Lasofoxifene 0.5 mg, but not lasofoxifene 0.25 mg, has shown reduction in the incidence of non-vertebral fractures. Bazedoxifene 20 mg has been associated with a significant reduction in the risk of non-vertebral fracture versus placebo and raloxifene 60 mg in women at higher baseline fracture risk. Neither raloxifene, lasofoxifene, nor bazedoxifene has shown an increase in the incidence of endometrial hyperplasia or carcinoma. All SERMs have been associated with increased venous thromboembolic events and hot flushes. SERMs are effective alternatives for women who cannot tolerate or are unwilling to take bisphosphonates and may be appropriate for women at higher risk of fracture, particularly younger women who expect to remain on therapy for many years and are concerned about the long-term safety of bisphosphonates.

Selective estrogen receptor modulator (SERM) lasofoxifene forms reactive quinones similar to estradiol

The bioactivation of both endogenous and equine estrogens to electrophilic quinoid metabolites has been postulated as a contributing factor in carcinogenic initiation and/or promotion in hormone sensitive tissues. Bearing structural resemblance to estrogens, extensive studies have shown that many selective estrogen receptor modulators (SERMs) are subject to similar bioactivation pathways. Lasofoxifene (LAS), a third generation SERM which has completed phase III clinical trials for the prevention and treatment of osteoporosis, is currently approved in the European Union for this indication. Previously, Prakash et al. (Drug Metab. Dispos. (2008) 36, 1218-1226) reported that similar to estradiol, two catechol regioisomers of LAS are formed as primary oxidative metabolites, accounting for roughly half of the total LAS metabolism. However, the potential for further oxidation of these catechols to electrophilic o-quinones has not been reported. In the present study, LAS was synthesized and its oxidative metabolism investigated in vitro under various conditions. Incubation of LAS with tyrosinase, human liver microsomes, or rat liver microsomes in the presence of GSH as a trapping reagent resulted in the formation of two mono-GSH and two di-GSH catechol conjugates which were characterized by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Similar conjugates were also detected in incubations with P450 3A4, P450 2D6, and P450 1B1 supersomes. Interestingly, these conjugates were also detected as major metabolites when compared to competing detoxification pathways such as glucuronidation and methylation. The 7-hydroxylasofoxifene (7-OHLAS) catechol regioisomer was also synthesized and oxidized either chemically or enzymatically to an o-quinone that was shown to form depurinating adducts with DNA. Collectively, these data show that analogous to estrogens, LAS is oxidized to catechols and o-quinones which could potentially contribute to in vivo toxicity for this SERM.

Extraskeletal benefits and risks of calcium, vitamin D and anti-osteoporosis medications

Drugs used for the prevention and the treatment of osteoporosis exert various favourable and unfavourable extra-skeletal effects whose importance is increasingly recognized notably for treatment selection.

INTRODUCTION

The therapeutic armamentarium for the prevention and the treatment of osteoporosis is increasingly large, and possible extra-skeletal effects of available drugs could influence the choice of a particular compound.

METHODS

The present document is the result of a national consensus, based on a systematic and critical review of the literature.

RESULTS

Observational research has suggested an inverse relationship between calcium intake and cardiovascular diseases, notably through an effect on blood pressure, but recent data suggest a possible deleterious effect of calcium supplements on cardiovascular risk. Many diverse studies have implicated vitamin D in the pathogenesis of clinically important non-skeletal functions or diseases, especially muscle function, cardiovascular disease, autoimmune diseases and common cancers. The possible effects of oral or intravenous bisphosphonates are well-known. They have been associated with an increased risk of oesophageal cancer or atrial fibrillation, but large-scale studies have not found any association with bisphosphonate use. Selective oestrogen receptor modulators have demonstrated favourable or unfavourable extra-skeletal effects that vary between compounds. Strontium ranelate has a limited number of non-skeletal effects. A reported increase in the risk of venous thromboembolism is not found in observational studies, and very rare cases of cutaneous hypersensitivity reactions have been reported. Denosumab has been introduced recently, and its extra-skeletal effects still have to be assessed.

CONCLUSION

Several non-skeletal effects of bone drugs are well demonstrated and influence treatment choices.

GPER/GPR30 and Regulation of Vascular Tone and Blood Pressure

Natural estrogens such as 17β-estradiol are endogenous vasodilators and have been implicated in the gender differences of hypertension. These hormones activate estrogen receptors ERα and ERβ, which mediate part of estrogen-dependent vasodilation. In addition, a novel G protein-coupled estrogen-binding receptor termed GPER/GPR30 has been identified that is expressed in the cardiovascular system. Using knock-out animals or drugs selectively targeting GPER/GPR30, a significant role for this receptor as a mediator of acute estrogen-dependent vasodilation involving nitric oxide (NO) and blood pressure-lowering activity has been demonstrated. The accumulating evidence that GPER/GPR30 is responsible for control of vascular tone indicates that this receptor may represent a novel drug target for pharmacologic treatment of hypertension in postmenopausal women and possibly also men.

The G protein-coupled estrogen receptor GPER/GPR30 as a regulator of cardiovascular function

Endogenous estrogens are important regulators of cardiovascular homeostasis in premenopausal women and delay the development of hypertension and coronary artery disease. These hormones act via three different estrogen receptors affecting both gene transcription and rapid signaling pathways in a complex interplay. In addition to the classical estrogen receptors ERα and ERβ, which are known mediators of estrogen-dependent vascular effects, a G protein-coupled estrogen receptor termed GPER that is expressed in the cardiovascular system has recently been identified. Endogenous human 17β-estradiol, selective estrogen receptor modulators (SERMs) including tamoxifen and raloxifene, and selective estrogen receptor downregulators (SERDs) such as ICI 182,780 are all agonists of GPER, which has been implicated in the regulation of vasomotor tone and protection from myocardial ischemia/reperfusion injury. As a result, understanding the individual role of ERα, ERβ, and GPER in cardiovascular function has become increasingly complex. With accumulating evidence that GPER is responsible for a variety of beneficial cardiovascular effects of estrogens, this receptor may represent a novel target to develop effective strategies for the treatment of cardiovascular diseases by tissue-specific, selective activation of estrogen-dependent molecular pathways devoid of side effects seen with conventional hormone therapy.