Effects of conjugated estrogens/bazedoxifene on lipid and coagulation variables: a randomized placebo- and active-controlled trial

Comprehensive meta-analysis of the effects of oral medroxyprogesterone acetate plus conjugated equine oestrogens on the lipid profile in women: Insights from randomized controlled trials

BACKGROUND

Menopause is associated with elevated cardiovascular risk due to the loss of the cardioprotective effect of oestrogens. Postmenopausal women are often prescribed hormone replacement therapy (HRT) in order to control menopause symptoms and correct hormone imbalances; however, HRT can impact serum lipids' concentrations. At present, data on the effect of the administration of medroxyprogesterone acetate plus conjugated equine oestrogens (MPACEE) on the lipid profile in females are uncertain, as the investigations conducted so far have produced conflicting results. Thus, we aimed to clarify the impact of MPACEE prescription on the serum lipids' values in women by means of a systematic review and meta-analysis of randomized controlled trials (RCTs).

METHODS

We employed a random-effects model based on the DerSimonian and Laird method to determine the combined estimates of the intervention's impact on the lipid profile. The computation of the weighted mean difference (WMD) and its corresponding 95% confidence interval (CI) relied on the mean and standard deviation values from both the MPACEE and control group, respectively.

RESULTS

A total of 53 RCTs were included in the meta-analysis with 68 RCT arms on total cholesterol (TC), 70 RCT arms on low-density lipoprotein cholesterol (LDL-C) and triglycerides (TG), and 69 RCT arms on high-density lipoprotein cholesterol (HDL-C). Administration of MPACEE resulted in a significant reduction of TC (WMD = -11.93 mg/dL; 95% CI: -13.42, -10.44; p < .001) and LDL-C (WMD = -16.61 mg/dL; 95% CI: -17.97, -15.26; p < .001) levels, and a notable increase in HDL-C (WMD = 3.40 mg/dL; 95% CI: 2.93, 3.86; p < .001) and TG (WMD = 10.28 mg/dL; 95% CI: 7.92, 12.64; p < .001) concentrations. Subgroup analysis revealed that changes in the lipid profile were influenced by several factors: body mass index (for TC, HDL-C, TG), MPACEE dosages (for TC, LDL-C, HDL-C, TG), age (for TC, LDL-C, HDL-C, TG), durations of the intervention (for TC, LDL-C, HDL-C, TG), continuous/sequential administration of MPACEE (continuous for TC; sequential for LDL-C, TG) administration of MPACEE and serum lipids' concentrations before enrolment in the RCT (for TC, LDL-C, HDL-C, TG).

CONCLUSIONS

MPACEE administration can influence serum lipids' concentrations in females by raising HDL-C and TG levels and reducing LDL-C and TC values. Therefore, postmenopausal women who suffer from hypercholesterolaemia might benefit from this type of HRT.

Estrogens in Adipose Tissue Physiology and Obesity-Related Dysfunction

Menopause-related decline in estrogen levels is accompanied by a change in adipose tissue distribution from a gynoid to an android and an increased prevalence of obesity in women. These unfavorable phenomena can be partially restored by hormone replacement therapy, suggesting a significant role for estrogen in the regulation of adipocytes' function. Indeed, preclinical studies proved the involvement of these hormones in adipose tissue development, metabolism, and inflammatory activity. However, the relationship between estrogen and obesity is bidirectional. On the one hand-their deficiency leads to excessive fat accumulation and impairs adipocyte function, on the other-adipose tissue of obese individuals is characterized by altered expression of estrogen receptors and key enzymes involved in their synthesis. This narrative review aims to summarize the role of estrogen in adipose tissue development, physiology, and in obesity-related dysfunction. Firstly, the estrogen classification, synthesis, and modes of action are presented. Next, their role in regulating adipogenesis and adipose tissue activity in health and the course of obesity is described. Finally, the potential therapeutic applications of estrogen and its derivates in obesity treatment are discussed.

Sex Differences in Nonalcoholic Fatty Liver Disease: Estrogen Influence on the Liver-Adipose Tissue Crosstalk

Significance: Nonalcoholic fatty liver disease (NAFLD) is a hepatic and systemic disorder with a complex multifactorial pathogenesis. Owing to the rising incidence of obesity and diabetes mellitus, the prevalence of NAFLD and its impact on global health care are expected to increase in the future. Differences in NAFLD exist between males and females, and among females depending on their reproductive status. Clinical and preclinical data show that females in the fertile age are more protected against NAFLD, and studies in postmenopausal women and ovariectomized animal models support a protective role for estrogens. Recent Advances: An efficient crosstalk between the liver and adipose tissue is necessary to regulate lipid and glucose metabolism, protecting the liver from steatosis and insulin resistance contributing to NALFD. New advances in the knowledge of sexual dimorphism in liver and adipose tissue are providing interesting clues about the sex differences in NAFLD pathogenesis that could inspire new therapeutic strategies. Critical Issues: Sex hormones influence key master regulators of lipid metabolism and oxidative stress in liver and adipose tissue. All these sex-biased metabolic adjustments shape the crosstalk between liver and adipose tissue, contributing to the higher protection of females to NAFLD. Future Directions: The development of novel drugs based on the protective action of estrogens, but without its feminizing or undesired side effects, might provide new therapeutic strategies for the management of NAFLD. Antioxid. Redox Signal. 35, 753-774.

Effects of conjugated estrogen and bazedoxifene on hemostasis and thrombosis in mice

Estrogen-progestin therapy was previously considered as the standard of care for managing bothersome symptoms associated with menopause, but it increases risks of breast cancer and of thromboembolism. The combination of conjugated estrogen (CE) with bazedoxifene (BZA) named tissue-selective estrogen complex (TSEC) was designed to minimize or even abrogate the undesirable effects on breast, while maintaining the beneficial effects such as prevention of osteoporosis and suppression of climacteric symptoms. The risk on thromboembolism associated with TSEC is unknown, although the clinical available data are reassuring. The aim of this study was to define the impact of a chronic administration of CE, BZA or CE + BZA on hemostasis and thrombosis in ovariectomized mice. As expected, CE, but not BZA neither CE + BZA, induced uterine and vagina hypertrophy. As previously demonstrated for 17β-estradiol (E2), we found that CE (i) increased tail-bleeding time, (ii) prevented occlusive thrombus formation in injured carotid artery and (iii) protected against collagen/epinephrine-induced thromboembolism. Thus, whereas BZA antagonized CE action on reproductive tissues, it had no impact on the effect of CE on hemostasis, thromboembolism and arterial thrombosis in mice. CE + BZA shared the anti-thrombotic actions of CE in these mouse models. If a similar process is at work in women, CE combined with BZA could contribute to minimize the risk of thrombosis associated with hormone replacement therapy.

[Towards an optimization of the modulation of the estrogen receptor during menopausal hormonal therapy]

Women now live more than a third of their lives after the onset of menopause. The decline in endogenous estrogen production during this period is accompanied by functional disorders that affect quality of life. These symptoms may be relieved by menopausal hormone therapy (MHT) initially based on the administration of equine conjugated estrogens (mainly in the United States, oral route) or the natural estrogen, 17β-estradiol (in Europe, transdermal route). Estrogen receptor α (ERα), but not ERβ, mediates most of the physiological effects of estrogens. ERα belongs to the superfamily of nuclear receptors and regulates the transcription of genes via its activation functions AF1 and AF2. In addition to these classical genomic actions, estrogens can activate a subpopulation of ERα present at the cell membrane and thereby induce rapid signals. In this review, we will summarize the evolution of MHTs in last decades, as well as treatments that use various selective estrogen receptor modulators (SERMs). Next, we will describe recent advances in the understanding of the mechanisms of estrogen action, in particular the respective roles of nuclear and membrane ERα as well as the potential implications for future therapies.

The antagonist properties of Bazedoxifene after acute treatment are shifted to stimulatory action after chronic exposure in the liver but not in the uterus

A promising alternative to conventional hormone therapy for postmenopausal symptoms is treatment combining Bazedoxifene (BZA), a third-generation selective estrogen receptor modulator (SERM), and conjugated equine estrogen (CE). This combination is also known as a tissue-selective estrogen complex (TSEC). Understanding the tissue-specific actions of SERMs and the TSEC remains a major challenge to try to predict their clinical effects. The aim of this study was to compare acute versus chronic treatment with BZA, CE or CE + BZA in two major targets of estrogens, the uterus and the liver. In these two tissues, acute treatment with CE, but not with BZA, induced similar gene expression change than the most important endogenous estrogen, 17-β estradiol (E2). Acute induction of gene expression by E2 or by CE was antagonized by the addition of BZA. Concomitantly, BZA alone or in combination with E2 or CE induced a partial degradation of ERα protein after acute exposure. In uterus, chronic treatment of BZA alone had no impact on tissue weight gain or on epithelial cell proliferation, and also antagonized CE-effect in uterus, thereby mimicking the acute effect. By contrast, in the liver, chronic BZA and CE + BZA elicited agonistic transcriptional effects similar to those of CE alone. In addition, at variance to BZA acute effect, no change in ERα protein abundance was observed after chronic treatment in this tissue. These experimental in vivo data highlight a new aspect of the time-dependent tissue-specific action of BZA or TSEC, i.e. they can act acutely as antagonists but become agonists after chronic treatment. This shift was observed in liver tissue, but not in proliferative sex target such as the uterus.

Towards optimization of estrogen receptor modulation in medicine

Women now spend more than one-third of their lives in the postmenopausal years, and the decline of endogenous estrogen production during menopause is accompanied by a series of functional disorders that affect the quality of life. These symptoms could be alleviated or even totally suppressed by menopausal hormone therapy (MHT), initially based on natural estrogens extracted from the urine of pregnant mares (mainly in the USA, using the oral route) and later from the synthesis of the natural estrogen, 17β-estradiol (mainly in Europe, in particular using the transdermal route). Estrogen receptor (ER) α is the main receptor mediating the physiological effects of estrogens. ERα belongs to the nuclear receptor superfamily and activates gene transcription in a time and tissue-specific manner through two distinct activation functions (AF), AF1 and AF2. In addition to these classical genomic actions, ERα also mediates membrane initiated signaling enabling rapid actions of estrogen, potentially along or in interaction with other receptors. Here, we provide a brief historical overview of MHT, and we then highlight recent advances in the characterization of new treatments based on the association of estrogens with selective estrogen receptor modulators (SERMs) or on the modulation of nuclear or membrane ERα.

Timing and persistence of effect of conjugated estrogens/bazedoxifene in postmenopausal women

OBJECTIVE

The aim of the study was to determine the time course of effect with conjugated estrogens/bazedoxifene (CE/BZA) in nonhysterectomized postmenopausal women in five phase 3 trials.

METHODS

This post hoc analysis identified when CE 0.45 mg/BZA 20 mg and CE 0.625 mg/BZA 20 mg first achieved a statistically significant difference (P < 0.05) versus placebo in individual trials and the duration the difference persisted for prespecified efficacy endpoints.

RESULTS

CE/BZA significantly reduced hot flush frequency beginning at weeks 2 to 4 and severity at weeks 3 to 6; benefits were maintained through month 24. Significant improvements in lumbar spine, total hip, femoral neck, and femoral trochanter bone mineral density were evident at month 6 or 12 and changes in bone turnover markers at month 3 or 6; benefits were maintained throughout the studies (12 or 24 mo). In symptomatic women with less than 5% vaginal superficial cells at baseline, vaginal maturation index was significantly improved by week 4. Reductions in parabasal cells were maintained throughout the studies (through months 3 and 24), but superficial cell count changes persisted only with the higher CE/BZA dose. Menopause-Specific Quality of Life total and vasomotor domain scores were improved at all assessments, from months 3 through 24. Some measures of sleep, especially quality and time to fall asleep, improved during weeks 4 to 8 and were maintained in a majority of weeks thereafter.

CONCLUSIONS

In the context of studies designed primarily to evaluate efficacy at final study endpoints, both doses of CE/BZA achieved significance versus placebo at early assessments for most outcomes, and benefits were well maintained.

An Overview of the Clinical Efficacy and Safety of Tissue Selective Estrogen Complex: From the Selective Estrogens, Menopause, and Response to Therapy (SMART) Trials

Hormone therapy (HT) is the most effective treatment for menopausal symptoms, and reduces both spinal and non-spinal postmenopausal osteoporotic fractures. However, a Women's Health Initiative (WHI) trial revealed that progestin-containing HT is associated with higher incidences of breast cancer and coronary heart disease than those associated with placebo. Tissue selective estrogen complex (TSEC) is a novel progestin-free HT option composed of conjugated estrogens (CE) and a selective estrogen receptor modulator. CE at a dose of 0.45 mg combined with 20 mg of bazedoxifene was the first TSEC medication approved in the United States and Korea for women with moderate to severe menopause-related vasomotor symptoms (VMS) and for preventing postmenopausal osteoporosis. This review summarizes the clinical efficacy, safety, and tolerability of TSEC as obtained from the five SMART clinical trials.

The evolving role of oral hormonal therapies and review of conjugated estrogens/bazedoxifene for the management of menopausal symptoms

This review describes the evolving role of oral hormone therapy (HT) for treating menopausal symptoms and preventing osteoporosis, focusing on conjugated estrogens/bazedoxifene (CE/BZA). Estrogens alleviate hot flushes and prevent bone loss associated with menopause. In nonhysterectomized women, a progestin should be added to estrogens to reduce the risk of endometrial cancer. Use of HT declined since the Women's Health Initiative (WHI) studies showed that HT does not prevent coronary heart disease (CHD) and that conjugated estrogens/medroxyprogesterone acetate increased the risk of invasive breast cancer after nearly 5 years of use. However, re-analyses of the WHI data suggest that some risks (eg, CHD, all-cause mortality) may be reduced when HT is initiated in women <60 years of age and <10 years since menopause, compared with later. CE/BZA is the first menopausal HT without a progestogen for nonhysterectomized women. Instead, BZA, a selective estrogen receptor modulator, in combination with CE, protects against estrogenic effects on uterine and breast tissue. Data from 5 large, randomized clinical trials show that CE/BZA reduces hot flush frequency/severity, prevents bone loss, reduces bone turnover, improves the vaginal maturation index and ease of lubrication, and improves some measures of sleep and menopause-specific quality of life. In studies of up to 2 years, there was no increase in endometrial hyperplasia, vaginal bleeding, breast density, or breast pain/tenderness compared with placebo. Venous thromboembolism and stroke are risks of all estrogen-based therapies. The choice of HT should be individualized, with consideration of the risk/benefit profile and tolerability of therapy, as well as patient preferences.

Effects of Hormone Therapy on Oxidative Stress in Postmenopausal Women with Metabolic Syndrome

The aim of this study was to determine the effect of oral hormone therapy (HT) on oxidative stress (OS) in postmenopausal women with metabolic syndrome (MetS). A randomized, double blind, placebo-controlled trial was carried out. We formed four groups of 25 women each; healthy (HW) and MetS women (MSW) were assigned to HT (1 mg/day of estradiol valerate plus 5 mg/10 day of medroxiprogesterone) or placebo. We measured plasma lipoperoxides, erythrocyte superoxide dismutase and glutathione peroxidase, total plasma antioxidant status and uric acid, as OS markers. Alternative cut-off values of each parameter were defined and a stress score (SS) ranging from 0 to 7 was used as total OS. MetS was defined according to National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATPIII) criteria. Participants were seen at baseline, 3 and 6 months. After 6 months, MetS decreased in MSW-HT (48%), their triglycerides and high-density lipoprotein cholesterol (HDL-c) improved; in the other groups no difference was found. SS in MSW-HT decreased (3.8 ± 0.3 to 1.7 ± 0.3, p < 0.05) and OS was also reduced (44%), this effect was evident since 3 mo. HW-HT with high OS also decreased (40%). In placebo groups there was no change. Our findings suggest that HT improve lipids and OS associated to MetS in postmenopausal women.

Effect of selective estrogen receptor modulators on metabolic homeostasis

Selective estrogen receptor modulators (SERMs) are estrogen receptor (ER) ligands that exhibit either estrogen agonistic or antagonistic activity in a tissue-specific manner. The first and second generation SERMs, tamoxifen and raloxifene, are used for treatment of ER positive breast cancer and postmenopausal osteoporosis respectively. The third-generation SERM, bazedoxifene (BZA), effectively prevents osteoporosis while blocking the estrogenic stimulation in breast and uterus. Notably, BZA combined with conjugated estrogens (CE) in a tissue-selective estrogen complex (TSEC) is a new menopausal treatment. Postmenopausal estrogen deficiency predisposes to metabolic syndrome and type 2 diabetes, and therefore the effects of SERMs and TSECs on metabolic homeostasis are gaining attention. In this article, we summarize current knowledge about the impact of SERMs on metabolic homeostasis and metabolic disorders in animal models and postmenopausal women.

The Tissue-Selective Estrogen Complex: A Review of Current Evidence

The tissue-selective estrogen complex (TSEC) has recently entered the market for the treatment of postmenopausal osteoporosis, and is particularly targeted to women with significant vasomotor symptoms. This review appraises the evidence behind the only approved TSEC to-date, a combination of bazedoxifene and conjugated estrogens, with regards to its efficacy and relevant safety concerns. The majority of evidence that has led to its approval is derived from the SMART study. This large phase III trial with several substudies was aimed at discerning the effects of the TSEC on various estrogen-responsive tissues in comparison to raloxifene and placebo. Overall, the evidence thus far suggests a superior improvement in lumbar bone mineral density of 1.01% ± 0.28% as well as decrease in the frequency of hot flushes. Regarding safety concerns, endometrial thickness did not change over the treatment course, and investigators also identified a modest reduction in breast density. While there was no difference in rates of venous thromboembolism between treatment and placebo groups in a 2-year follow-up period, the effects of the drug on coagulation profiles are similar to those seen with hormone replacement therapy. Thus, the drug's effects on venous thromboembolism risk over a longer treatment course remain unclear. In conclusion, the actual efficacy of the TSEC for postmenopausal osteoporosis remains as yet undefined, given the lack of fracture prevention data. The evidence thus far does seem to suggest a beneficial effect on vasomotor symptoms and a generally favorable side effect profile. However, it should be noted that only one study has addressed this question thus far, and so the repeatability of the findings is still in question.