Efficacy of bazedoxifene in reducing new vertebral fracture risk in postmenopausal women with osteoporosis: results from a 3-year, randomized, placebo-, and active-controlled clinical trial

Profile of bazedoxifene/conjugated estrogens for the treatment of estrogen deficiency symptoms and osteoporosis in women at risk of fracture

Decreasing levels of estrogens during menopause are associated with reduced bone density and an increased risk of osteoporosis. Many women also experience bothersome vasomotor and vaginal symptoms during the menopausal transition. Results of systematic reviews and meta-analyses of randomized controlled trials have shown that both systemic estrogen therapy or hormone therapy (estrogen combined with a progestin) are useful to prevent bone loss, and they are the most effective treatment for such climacteric symptoms as hot flushes, sweating, vaginal dryness, and dyspareunia. Unfortunately, estrogen therapy and hormone therapy increase the risk of endometrial and breast cancer, respectively. The selective estrogen receptor modulators (SERMs) result in positive estrogenic effects on bone, with no negative effects on the endometrium and breast but do not provide relief from postmenopausal symptoms. The combination of a SERM with estrogen as a tissue selective estrogen complex (TSEC) is a new strategy for the prevention of bone loss and the treatment of climacteric symptoms. This combination is particularly interesting from a clinical point of view, taking into account that estrogen alone did not increase breast cancer risk by the Women’s Health Initiative. TSEC is hypothesized to provide the benefits of estrogen-alone therapy, with an improved tolerability profile because the SERM component can make possible the elimination of progestin. The objective of this review was to critically evaluate the evidence from the reports published to date on the use of bazedoxifene (a third-generation SERM) in combination with conjugated estrogens in postmenopausal women. The conclusion is that effectively, the combination of bazedoxifene and conjugated estrogens may be a promising alternative to hormone therapy for the prevention of osteoporosis and the treatment of postmenopausal symptoms in non-hysterectomized postmenopausal women.

Therapeutic effect of aqueous extract from Ecliptae herba on bone metabolism of ovariectomized rats

OBJECTIVE

Ecliptae herba (EH) has long been used in China to strengthen bones. Accumulating evidence indicates that EH may have antiosteoporotic effects. The aim of this study was to evaluate the effects of aqueous EH extract (EHE) on rats that had osteoporosis-like features induced by ovariectomy, using aqueous Fructus Ligustri Lucidi extract as positive control agent.

METHODS

Three-month-old female rats that underwent ovariectomy were treated with EHE (1.4 g/kg per day). After 12 weeks, bone mineral density and bone histomorphometric indices of tibiae were measured. Protein and messenger RNA expressions of osteoprotegerin and receptor activator of nuclear factor κ-B ligand (RANKL) in tibiae were evaluated by immunohistochemistry and in situ hybridization. In addition, serum concentrations of osteocalcin, interleukin-1β, interleukin-6 (IL-6), calcitonin (CT), and parathyroid hormone were determined by enzyme-linked immunosorbent assay.

RESULTS

EHE treatment prevented body weight gain and loss of uterine wet weight in ovariectomized rats. It remarkably increased bone mass in ovariectomized rats compared with ovariectomized controls. EHE treatment significantly down-regulated RANKL expression in tibiae from ovariectomized rats compared with controls; however, it had no significant effect on osteoprotegerin expression. In addition, EHE treatment significantly reduced serum IL-6 levels and remarkably increased CT levels but had no effect on parathyroid hormone.

CONCLUSIONS

EHE increases bone mass in ovariectomized rats by inhibiting bone loss: down-regulated RANKL expression in tibiae and IL-6 level in serum, and up-regulated CT level in serum. This suggests that EHE may be developed as an alternative therapeutic agent for osteoporosis induced by postmenopause.

Tissue-selective estrogen complexes for postmenopausal women

Although hormone therapy using estrogens plus progestogens (EPT) is effective for the management of menopausal symptoms (e.g., vasomotor symptoms and vulvar/vaginal atrophy) and prevention/treatment of postmenopausal osteoporosis, EPT is associated with safety and tolerability concerns. A new alternative to EPT is the tissue selective estrogen complex (TSEC), which partners a selective estrogen receptor modulator (SERM) with one or more estrogens and is designed to treat menopausal symptoms and prevent postmenopausal osteoporosis without the tolerability concerns associated with EPT. The first TSEC to reach advanced clinical development is a combination of the SERM bazedoxifene (BZA) with conjugated estrogens (CE). BZA has been shown to inhibit the stimulatory activity of CE on uterine tissue and breast in vitro and in vivo. In clinical studies, BZA/CE treatment has been associated with significant improvements in menopausal symptoms including hot flushes and vulvar/vaginal atrophy and significant increases in bone mineral density, coupled with reductions in bone turnover marker levels and improvements in sleep and health-related quality of life. Additionally, BZA/CE has been shown to have a neutral effect on endometrial and breast tissue because BZA inhibits the stimulatory effects of estrogens in tissue-selective fashion in these 2 organs. Taken together, results of these preclinical and clinical studies indicate that the benefits of estrogens for treating menopausal symptoms are maintained with BZA/CE without endometrial or breast stimulation, resulting in a safe and effective treatment for symptomatic postmenopausal women.

Cost-effectiveness of bazedoxifene versus raloxifene in the treatment of postmenopausal women in Spain

BACKGROUND

The purpose of this study was to assess the cost-effectiveness of bazedoxifene and raloxifene for prevention of vertebral and nonvertebral fractures among postmenopausal Spanish women aged 55-82 years with established osteoporosis and a high fracture risk.

METHODS

A Markov model was developed to represent the transition of a cohort of postmenopausal osteoporotic women through different health states, ie, patients free of fractures, patients with vertebral or nonvertebral fractures, and patients recovered from a fracture. Efficacy data for bazedoxifene were obtained from the Osteoporosis Study. The perspective of the Spanish National Health Service was chosen with a time horizon of 27 years. Costs were reported in 2010 Euros. Deterministic results were presented as expected cost per quality-adjusted life-year (QALY), and probabilistic results were represented in cost-effectiveness planes.

RESULTS

In deterministic analysis, the expected cost per patient was higher in the raloxifene cohort (€13,881) than in the bazedoxifene cohort (€13,436). QALYs gained were slightly higher in the bazedoxifene cohort (14.56 versus 14.54). Results from probabilistic sensitivity analysis showed that bazedoxifene has a slightly higher probability of being cost-effective for all threshold values independent of the maximum that the National Health Service is willing to pay per additional QALY.

CONCLUSION

Bazedoxifene was shown to be a cost-effective treatment option for the prevention of fractures in Spanish women with postmenopausal osteoporosis and a high fracture risk. When comparing bazedoxifene with raloxifene, it may be concluded that the former is the dominant strategy.

Health technology assessment in osteoporosis

We review the various aspects of health technology assessment in osteoporosis, including epidemiology and burden of disease, and assessment of the cost-effectiveness of recent advances in the treatment of osteoporosis and the prevention of fracture, in the context of the allocation of health-care resources by decision makers in osteoporosis. This article was prepared on the basis of a symposium held by the Belgian Bone Club and the discussions surrounding that meeting and is based on a review and critical appraisal of the literature. Epidemiological studies confirm the immense burden of osteoporotic fractures for patients and society, with lifetime risks of any fracture of the hip, spine, and forearm of around 40 % for women and 13 % for men. The economic impact is also large; for example, Europe's six largest countries spent €31 billion on osteoporotic fractures in 2010. Moreover, the burden is expected to increase in the future with demographic changes and increasing life expectancy. Recent advances in the management of osteoporosis include novel treatments, better fracture-risk assessment notably via fracture risk algorithms, and improved adherence to medication. Economic evaluation can inform decision makers in health care on the cost-effectiveness of the various interventions. Cost-effectiveness analyses suggest that the recent advances in the prevention and treatment of osteoporosis may constitute an efficient basis for the allocation of scarce health-care resources. In summary, health technology assessment is increasingly used in the field of osteoporosis and could be very useful to help decision makers efficiently allocate health-care resources.

Osteoporosis and treatments in Japan: management for preventing subsequent fractures

Prevalent fractures are major contributors to an increased risk of subsequent fractures, particularly in people with osteoporosis. While many studies have been conducted to assess the incidence of fracture in Japanese people with osteoporosis, far fewer have been conducted to assess the risk of subsequent fractures. This article reviews the morbidity, mortality, and risk of fracture in patients who are at high risk of subsequent fracture in Japan and the current treatment options available for these patients. Osteoporotic fractures in Japan are associated with high morbidity and mortality that result in significant financial and social costs. The rise in the proportion of elderly women in the Japanese population is contributing to a greater proportion of people with osteoporotic fractures and the high cost of osteoporosis. Although hip fractures have a significant effect on costs, a greater proportion of the Japanese population experience vertebral fractures. An increase in the incidence of vertebral fractures is concerning because preexisting vertebral fractures in older patients are associated with an increased risk of subsequent fractures. Hence, there is a clear rationale for pharmacological treatment of patients with prevalent vertebral fractures, or for those who are hospitalized or undergo surgery for osteoporotic fractures. Several pharmacological therapies are now available in Japan for the treatment of patients with osteoporosis. Understanding the consequences of subsequent fractures and the treatment options available for patients at high risk of subsequent fractures may contribute to clinical decision-making and improved outcomes for patients with osteoporosis.

Flavonoids as dietary regulators of nuclear receptor activity

Metabolic diseases such as obesity, type II diabetes, and dyslipidemia are a rising cause of mortality worldwide. The progression of many metabolic diseases is fundamentally regulated on the transcriptional level by a family of ligand-activated transcription factors, called nuclear receptors, which detect and respond to metabolic changes. Their role in maintaining metabolic homeostasis makes nuclear receptors an important pharmaceutical and dietary target. This review will present the growing evidence that flavonoids, natural secondary plant metabolites, are important regulators of nuclear receptor activity. Structural similarities between flavonoids and cholesterol derivatives combined with the promiscuous nature of most nuclear receptors provide a wealth of possibilities for pharmaceutical and dietary modulation of metabolism. While the challenges of bringing flavonoid-derived therapeutics to the market are significant, we consider this rapidly growing field to be an essential aspect of the functional food initiative and an important mine for pharmaceutical compounds.

The role of vitamin D supplementation in patients with rheumatic diseases

Vitamin D is a dietary vitamin that can also be synthesized in adequate amounts from cholesterol in most mammals exposed to sunlight. Vitamin D has classical roles in calcium and phosphate metabolism, and thus the skeleton; however, this molecule also has nonclassical effects that might influence the function of the immune, cardiovascular and endocrine systems. Vitamin D deficiency, due to insufficient sunlight exposure, dietary uptake and/or abnormalities in its metabolism, has been associated with rheumatic diseases, and both the classical and nonclassical effects of vitamin D might be of relevance to patients with rheumatic disease. However, conclusive data from intervention trials demonstrating the relationship between vitamin D levels and pathogenetic processes separate from classical effects of this molecule are lacking. Furthermore, the majority of studies linking vitamin D to health outcomes, harmful or beneficial, are observational in nature, linking clinical events to vitamin D exposure or serum levels of vitamin D metabolites. Evidence from high quality, prospective, double-blind, placebo-controlled, randomized trials should be obtained before vitamin D supplementation is recommended in the treatment of the many rheumatic conditions in which deficiency of this compound has been implicated. Herein, we review the evidence for vitamin D supplementation in the management of patients with rheumatic diseases.

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.

Safety concerns with the long-term management of osteoporosis

INTRODUCTION

Postmenopausal osteoporosis is a chronic disease that exerts a significant burden on both individuals and the community. Hence, there is a requirement for long-term treatment to be associated with a positive benefit-risk balance.

AREAS COVERED

In this descriptive review, the long-term safety of calcitonin, selective estrogen receptor modulators (SERMs), bisphosphonates, denosumab and strontium ranelate was reviewed based on randomized controlled trials of 3 years or longer supplemented by extension study data and data from large, observational studies.

EXPERT OPINION

Rare adverse events become apparent with all currently available treatments for osteoporosis with long-term therapy. Due to the rarity of these adverse events and to the worldwide burden of osteoporosis, the benefit-risk balance remains in favor of the beneficial effects of treatment on an outcome rather than the probability of an adverse effect. No single antiosteoporosis agent is appropriate for all patients. Treatment decisions should be made on an individual basis, taking into account the relative benefits and risks in different patient populations.

Effects of bazedoxifene acetate with and without conjugated equine estrogens on the breast of postmenopausal monkeys

OBJECTIVE

Concerns about increased breast cancer risk with estrogen and progestin therapy have led to an increased interest in progestin alternatives. The main objective of this study was to determine if bazedoxifene acetate (BZA), a new selective estrogen receptor modulator, will antagonize the proliferative and transcriptional effects of conjugated equine estrogens (CEE) in the breast.

METHODS

As part of a 20-month preclinical trial, 95 ovariectomized cynomolgus macaques (Macaca fascicularis) were randomized to receive no treatment or treatment with BZA (20 mg/d), CEE (0.45 mg/d), or BZA and CEE in combination (women's daily equivalent doses). The data presented here include breast effects after 6 months of treatment. Endpoints included histomorphometry, histopathological evaluations, gene microarray assays, polymerase chain reaction quantification of specific estrogen receptor α (ER-α) activity markers, and immunohistochemical detection of sex steroid receptors, and the proliferation marker Ki67.

RESULTS

BZA + CEE and BZA resulted in significantly less total epithelial density, lobular enlargement, and Ki67 immunolabeling in the terminal ducts compared with CEE alone (P < 0.05 for all). The addition of BZA to CEE antagonized the expression of ER-α-regulated genes such as GREB1 and TFF1 (P < 0.01 for both), whereas BZA alone had minimal effects on ER-α-mediated transcriptional activity. BZA and BZA + CEE did not significantly up-regulate genes related to cell cycle progression and proliferation. BZA with and without CEE also resulted in less lobular and terminal duct ER-α immunolabeling compared with control and CEE (P < 0.0001 for all).

CONCLUSIONS

These findings demonstrate that BZA given at a clinically relevant dose is an estrogen antagonist in the breast, supporting the idea that CEE + BZA may provide a lower breast cancer risk profile compared with traditional estrogen + progestin therapies.

Cost-effectiveness of bazedoxifene compared with raloxifene in the treatment of postmenopausal osteoporotic women

Bazedoxifene is a novel selective estrogen receptor modulator (SERM) for the prevention and treatment of osteoporosis. In addition to the therapeutic value of a new agent, evaluation of the cost-effectiveness compared with relevant alternative treatment(s) is an important consideration to facilitate healthcare decision making. This study evaluated the cost-effectiveness of bazedoxifene compared with raloxifene for the treatment of postmenopausal women with osteoporosis. The cost-effectiveness of treatment for 3 years with bazedoxifene was compared with raloxifene using an updated version of a previously validated Markov microsimulation model. Analyses were conducted from a Belgian healthcare payer perspective and, the base-case population was women (aged 70 years) with bone mineral density T-score ≤ -2.5. The effects of bazedoxifene and raloxifene on fracture risk were derived from the 3-year results of a randomized, double-blind, placebo-controlled and active-controlled study, including postmenopausal women with osteoporosis. The cost-effectiveness analysis based on efficacy data from the overall clinical trial indicated that bazedoxifene and raloxifene were equally cost-effective. When the results were examined based on the subgroup analysis of women at higher risk of fractures, bazedoxifene was dominant (lower cost for higher effectiveness) compared with raloxifene in most of the simulations. Sensitivity analyses confirmed the robustness of the results, which were largely independent of starting age of treatment, fracture risk, cost, and disutility. In addition, when the cost of raloxifene was reduced by one-half or when incorporating the raloxifene effects on reducing breast cancer, bazedoxifene remained cost-effective, at a threshold of €35,000 per quality-adjusted life-years gained, in 85% and 68% of the simulations, respectively. Under the assumption of improved antifracture efficacy of bazedoxifene over raloxifene in women with high risk of fractures, this study suggests that bazedoxifene can be considered cost-effective, and even dominant, when compared with raloxifene in the treatment of postmenopausal osteoporotic women.

Nuclear receptors and their selective pharmacologic modulators

Nuclear receptors are ligand-activated transcription factors and include the receptors for steroid hormones, lipophilic vitamins, sterols, and bile acids. These receptors serve as targets for development of myriad drugs that target a range of disorders. Classically defined ligands that bind to the ligand-binding domain of nuclear receptors, whether they are endogenous or synthetic, either activate receptor activity (agonists) or block activation (antagonists) and due to the ability to alter activity of the receptors are often termed receptor "modulators." The complex pharmacology of nuclear receptors has provided a class of ligands distinct from these simple modulators where ligands display agonist/partial agonist/antagonist function in a tissue or gene selective manner. This class of ligands is defined as selective modulators. Here, we review the development and pharmacology of a range of selective nuclear receptor modulators.

Bazedoxifene exhibits antiestrogenic activity in animal models of tamoxifen-resistant breast cancer: implications for treatment of advanced disease

PURPOSE

There is compelling evidence to suggest that drugs that function as pure estrogen receptor (ER-α) antagonists, or that downregulate the expression of ER-α, would have clinical use in the treatment of advanced tamoxifen- and aromatase-resistant breast cancer. Although such compounds are currently in development, we reasoned, based on our understanding of ER-α pharmacology, that there may already exist among the most recently developed selective estrogen receptor modulators (SERM) compounds that would have usage as breast cancer therapeutics. Thus, our objective was to identify among available SERMs those with unique pharmacologic activities and to evaluate their potential clinical use with predictive models of advanced breast cancer.

EXPERIMENTAL DESIGN

A validated molecular profiling technology was used to classify clinically relevant SERMs based on their impact on ER-α conformation. The functional consequences of these observed mechanistic differences on (i) gene expression, (ii) receptor stability, and (iii) activity in cellular and animal models of advanced endocrine-resistant breast cancer were assessed.

RESULTS

The high-affinity SERM bazedoxifene was shown to function as a pure ER-α antagonist in cellular models of breast cancer and effectively inhibited the growth of both tamoxifen-sensitive and -resistant breast tumor xenografts. Interestingly, bazedoxifene induced a unique conformational change in ER-α that resulted in its proteasomal degradation, although the latter activity was dispensable for its antagonist efficacy.

CONCLUSION

Bazedoxifene was recently approved for use in the European Union for the treatment of osteoporosis and thus may represent a near-term therapeutic option for patients with advanced breast cancer.

Obesity and bone

Recent studies indicate that fractures in obese postmenopausal women and older men contribute significantly to the overall fracture burden. The effect of obesity is to some extent site-dependent, the risk being increased for some fractures and decreased for others, possibly related to different patterns of falling and the presence or absence of soft tissue padding. Risk factors for fracture in obese individuals appear to be similar to those in the nonobese population, although falls may be particularly important in the obese. There is some evidence that the morbidity associated with fractures in obese individuals is greater than in the nonobese; however, a recent study indicates that the mortality associated with fracture is lower in obese and overweight people than in those of normal weight. The evidence base for strategies to prevent fractures in obese individuals is weak and is an important area for future research.

Why not use your own body weight to prevent falls? A randomized, controlled trial of balance therapy to prevent falls and fractures for elderly people who can stand on one leg for ≤15 s

BACKGROUND

Maintaining or improving motor (balance) ability is essential to extending the healthy lifespan of elderly people, and developing effective and efficient strategies to prevent falls of elderly people is an urgent. The purpose of this study was to determine the effects of balance exercise on fall and fracture prevention for elderly people with poor balance.

METHODS

A 6-month, randomized controlled trial was conducted to verify whether one-leg standing with eyes open for a total of 1 min, three times a day (dynamic flamingo exercise) prevents falls and fractures. Setting and participants were elderly people ≥75 years of age and one-leg standing time ≤15.0 s living in their own home. They were visiting orthopaedic clinics for orthopaedic handicaps. Subjects with poor balance were allowed to hold on to something. If a subject's lifted leg touched the ground during the exercise, they were allowed to lift it again and continue so that they stood on one leg for a total of 60 s.

RESULTS

The dynamic flamingo exercise group (410 people; 86 men, 324 women) and the no exercise group (455 people; 78 men, 377 women) were compared. After dynamic flamingo exercise for 6 months, significant differences were seen in the increase in one-leg standing time with eyes open (men right/left, women right/left), in the improvement in independence in daily living (women), number of people who fell during the 6 months (women), and adverse events (women). The number of fractures was not significantly different for men or women.

CONCLUSIONS

Dynamic flamingo exercise prevents falls but no significant difference was demonstrated in fracture prevention in elderly women with poor balance.

European guidance for the diagnosis and management of osteoporosis in postmenopausal women

Guidance is provided in a European setting on the assessment and treatment of postmenopausal women at risk of fractures due to osteoporosis.

INTRODUCTION

The International Osteoporosis Foundation and European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis published guidance for the diagnosis and management of osteoporosis in 2008. This manuscript updates these in a European setting.

METHODS

Systematic literature reviews.

RESULTS

The following areas are reviewed: the role of bone mineral density measurement for the diagnosis of osteoporosis and assessment of fracture risk, general and pharmacological management of osteoporosis, monitoring of treatment, assessment of fracture risk, case finding strategies, investigation of patients and health economics of treatment.

CONCLUSIONS

A platform is provided on which specific guidelines can be developed for national use.

Monoclonal antibodies for the treatment of osteoporosis

INTRODUCTION

Osteoporosis is a systemic skeletal disorder that weakens bones and increases the risk of fractures. It is caused by perturbations of bone remodeling, the coupled process whereby bone is continually resorbed and formed in small discrete units. Despite the availability of cost-effective pharmacological agents that reduce fracture risk, many patients who could benefit from treatment are not receiving it. Advances in the understanding of the molecular regulators of bone remodeling have led to the identification of new targets for therapeutic intervention. Monoclonal antibodies directed to these targets have recently been developed, providing new ways of modulating bone remodeling that may provide additional benefits beyond previously available therapy.

AREAS COVERED

An approved fully human monoclonal antibody to receptor activator of nuclear factor-κB ligand, the principal regulator of osteoclastic bone resorption, reduces the risk of fractures in postmenopausal women with osteoporosis. Monoclonal antibodies in development include inhibitors of sclerostin and Dickhopf1, with osteoanabolic activity that may be beneficial in the treatment of osteoporosis.

EXPERT OPINION

Monoclonal antibodies to molecular regulators of bone remodeling represent a new class of compounds for the management of osteoporosis and other skeletal disorders associated with an imbalance of bone resorption and formation.

[Third generation selective estrogen receptor modulators benefits beyond bone: effects on breast]

The selective estrogen receptor modulators (SERMs) are substances with estrogenic/anti-estrogen effect that act differently depending on the tissue and composition. Since the discovery that tamoxifen and raloxifene (RLX) had a breast cancer preventive effect, the search for the perfect SERM has been the goal. Thus, ospemifen, arzoxifene, lasofoxifene and bazedoxifene (BZA) appeared as third-generation SERMs. Among all them, only BZA reached the stage of clinical use. BZA has been shown to have an anti-estrogen effect in experimental studies, but not a protective effect on clinical breast cancer in pivotal clinical trials (301 and extensions). However, in these studies comparing BZA versus RLX and placebo, RLX has not shown the expected preventive effect on breast cancer. This lack of effect can be the consequence of the size and characteristics of BZA's studies in a population with low incidence of breast cancer.

Recommendations on the management of fragility fracture risk in women younger than 70 years

The risk for fragility fracture represents a problem of enormous magnitude. It is estimated that only a small fraction of women with this risk take the benefit of preventive measures. The relationship between estrogen and bone mass is well known as they are the other factors related to the risk for fracture. There are precise diagnostic methods, including a tool to diagnose the risk for fracture. Yet there continues to be an under-diagnosis, with the unrecoverable delay in instituting preventive measures. Women under the age of 70 years, being much more numerous than those older, and having risk factors, are a group in which it is essential to avoid that first fragility fracture. Today it is usual not to differentiate between the treatment and the prevention of osteoporosis since the common aim is to prevent fragility fractures. Included in this are women with osteoporosis or with low bone mass and increased risk for fracture, for whom risk factors play a primary role. There is clearly controversy over the type of treatment and its duration, especially given the possible adverse effects of long-term use. This justifies the concept of sequential treatment, even more so in women under the age of 70, since they presumably will need treatment for many years. Bone metabolism is age-dependent. In postmenopausal women under 70 years of age, the increase in bone resorption is clearly predominant, related to a sharp drop in estrogens. Thus a logical treatment is the prevention of fragility fractures by hormone replacement therapy (HRT) and, in asymptomatic women, selective estradiol receptor modulators (SERMs). Afterwards, there is a period of greater resorption, albeit less intense but continuous, when one could utilise anti-resorptive treatments such as bisphosphonates or denosumab or a dual agent like strontium ranelate. Bone formation treatment, such as parathyroid hormone (PTH), in women under 70 years will be uncommon. That is because it should be used in cases where the formation is greatly diminished and there is a high risk for fracture, something found in much older women.

Relationships between changes in bone mineral density or bone turnover markers and vertebral fracture incidence in patients treated with bazedoxifene

We analyzed the relationships between bone mineral density (BMD) or bone turnover marker (BTM) changes and vertebral fracture incidence in women treated with bazedoxifene using a post hoc analysis from a 3-year randomized, placebo-controlled study evaluating the effect of bazedoxifene (20 or 40 mg) on fracture risk reduction. BMD was assessed at baseline and every 6 months for 3 years. Osteocalcin and C-telopeptide of type I collagen were assessed at baseline and at 3, 12, and 36 months. Vertebral fractures were assessed with a semiquantitative visual assessment. Data were available for 5,244 women, of whom 3,476 were treated with bazedoxifene. Using a logistic regression analysis and the classical Li approach, the proportion of fracture incidence explained by BMD change after 3 years of bazedoxifene treatment was 29 % for the total hip and 44 % for the femoral neck. The proportion of treatment explained by lumbar BMD change could not be quantified accurately because of the significant interaction between treatment and change in BMD. With the same model, the 12-month BTM changes explained up to 29 % of the fracture risk reduction observed with the two forms of bazedoxifene. In women treated with bazedoxifene, changes in femoral neck BMD, hip BMD, or BTMs explained a moderate proportion of the fracture risk reduction observed during the 3 years of follow-up. However, BMD or BTM changes cannot be recommended for individual monitoring of women treated with bazedoxifene.

A Bayesian path analysis to estimate causal effects of bazedoxifene acetate on incidence of vertebral fractures, either directly or through non-linear changes in bone mass density

BACKGROUND/AIMS

Bone mass density values have been related with risk of vertebral fractures in post-menopausal women. However, bone mass density is not perfectly accurate in predicting risk of fracture, which decreases its usefulness as a surrogate in clinical trials. We propose a modeling framework with three interconnected parts to improve the evaluation of bone mass density accuracy in forecasting fractures after treatment.

METHODS

The modeling framework includes: (1) a piecewise regression to describe non-linear temporal BMD changes more accurately than crude percent changes, (2) a structural equation model to analyze interdependencies among vertebral fractures and their potential risk factors in preference to regression techniques that consider only directional associations, and (3) a counterfactual causal interpretation of the direct and indirect relationships between treatment and occurrence of vertebral fractures. We apply the methods to BMD repeated measurements from a study of the effect of bazedoxifene acetate on incident vertebral fractures in three different geographical regions.

RESULTS

We made four observations: (1) bone mass density changes varied largely across participants, (2) baseline age and body mass index influenced baseline bone mass density that, in turn, had an effect on prevalent fractures, (3) direct and/or indirect effects of bazedoxifene acetate on incident fractures were different across regions, and (4) estimates of indirect effects were sensible to the presence of post-treatment unmeasured confounders. In one region, around 40% of the bazedoxifene acetate effect on the occurrence of fracture is explained by its effect on bone mass density. Under the counterfactual approach, these 40% represent the average difference in the occurrence of fracture observed for untreated individuals when their bone mass density values are set at the value under bazedoxifene acetate versus under placebo.

CONCLUSIONS

Computational methods are available to evaluate and interpret the surrogacytic capability of a biomarker of a primary outcome.

Adverse drug reactions to osteoporosis treatments

Treatments for postmenopausal osteoporosis are generally safe, but are linked to some rare serious adverse drug reactions, for which causality is not always certain. The bisphosphonates are associated with gastrointestinal effects, acute phase reactions, and musculoskeletal pain, and, more rarely, cases of atrial fibrillation, subtrochanteric fracture, osteonecrosis of the jaw, cutaneous hypersensitivity reactions and renal impairment. It is too soon for pharmacovigilance data on denosumab, but it has been associated with cutaneous effects and possibly osteonecrosis of the jaw (to date, only in metastatic cancer). The selective estrogen receptor modulators may induce hot flushes and leg cramps, and--more rarely--venous thromboembolism and stroke. Strontium ranelate is associated with headache, nausea and diarrhea, and, more rarely, cutaneous hypersensitivity reactions and venous thromboembolism, while teriparatide and parathyroid hormone(1-84) are associated with headache, nausea, dizziness and limb pain. The management of osteoporosis should entail weighing the probability of adverse reactions against the benefits of therapy--that is, reduction of fracture risk.

The tissue selective estrogen complex: a promising new menopausal therapy

Menopause is associated with health concerns including vasomotor symptoms, vulvar/vaginal atrophy (VVA), and osteoporosis. Estrogen therapy or combined estrogen-progestin therapy (EPT) are primary treatment options for menopausal symptom relief and osteoporosis prevention. Because EPT has been associated with some safety/tolerability concerns relating to undesirable effects of estrogen and progestin, alternative options are needed. The tissue selective estrogen complex (TSEC) is a novel class of agents pairing a selective estrogen receptor modulator (SERM) with 1 or more estrogens. The TSEC combines the established efficacy of estrogens on menopausal symptoms and bone with the protective effects of a SERM on the reproductive tract. The pairing of bazedoxifene (BZA) with conjugated estrogens (CE) has been evaluated in a series of phase 3 clinical trials. BZA 20 mg/CE 0.45 mg and BZA 20 mg/CE 0.625 mg have shown efficacy in reducing the frequency and severity of hot flushes, relieving VVA symptoms, and maintaining bone mass while protecting the endometrium and breast. These BZA/CE doses have been associated with a favorable safety/tolerability profile, with higher rates of cumulative amenorrhea and lower incidences of breast pain than those reported for EPT. Thus, BZA/CE may be a promising alternative to conventional EPT for treating non-hysterectomized, postmenopausal women.

Bazedoxifene: the evolving role of third-generation selective estrogen-receptor modulators in the management of postmenopausal osteoporosis

Osteoporosis is a significant public health concern, particularly for postmenopausal women. Current treatment options may not be appropriate for all women. Selective estrogen-receptor modulators (SERMs) are a class of molecules with tissue-selective activity. Bazedoxifene is currently in clinical development for the prevention and treatment of postmenopausal osteoporosis. In a 2-year, phase III, osteoporosis prevention study (N = 1583), bazedoxifene 10, 20, and 40 mg was shown to preserve bone mineral density and decrease biochemical markers of bone turnover compared with placebo in postmenopausal women at risk for osteoporosis. In a pivotal 3-year, phase III, osteoporosis treatment study (N = 7492), bazedoxifene 20 and 40 mg significantly reduced the incidence of new vertebral fractures compared with placebo (p < 0.05 for both) in postmenopausal women with osteoporosis. In a post hoc subgroup analysis of women at higher risk for fracture (n = 1772), bazedoxifene 20 mg significantly reduced the risk of nonvertebral fractures versus placebo (p = 0.02) and raloxifene 60 mg (p = 0.05). Bazedoxifene 20 mg has demonstrated sustained efficacy in reducing the risk of vertebral fractures over 5 and 7 years. Overall, bazedoxifene was generally safe and well tolerated, with favorable endometrial and breast safety profiles. As with other SERMs, the rate of deep vein thrombosis was higher in the bazedoxifene groups compared with placebo at 3 and 5 years. Considering its demonstrated efficacy and safety, bazedoxifene may be an appropriate osteoporosis therapy for women who cannot take or are unwilling to take bisphosphonates because of safety or tolerability issues. Bazedoxifene may also be appropriate for younger women at increased fracture risk who are concerned about the effects of long-term bisphosphonate therapy. This article reviews the results of key clinical trials of bazedoxifene for the prevention and treatment of postmenopausal osteoporosis and describes its role in clinical practice.

Medical treatment of osteoporotic vertebral fractures

A vertebral fracture is a serious symptom of osteoporosis. Vertebral fractures cause moderate-to-severe back pain for a shorter or longer duration, increase the risk of a subsequent vertebral fracture approximately four-fold, reduce quality of life significantly and are associated with increased mortality. In order to choose the optimal treatment for the patient, the severity and type of osteoporosis should be investigated. Prevention of new osteoporotic fractures can be accomplished through treatment with both antiresorptive and anabolic treatments. The antiresorptive treatment modalities comprise calcium, vitamin D, bisphosphonates, hormone therapy, selective oestrogen receptor modulators (SERMs), strontium ranelate, receptor activator of NF-kB ligand (RANKL) antibody and calcitonin. The anabolic treatments comprise teriparatide and parathyroid hormone [(PTH)-(1-84)]. Adherence with treatment of osteoporosis is generally poor and therefore once the choice of treatment has been made and the patient has been instructed properly, long-term adherence to the treatment should be secured through information and regular control visits.

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.

Effect of alendronate for reducing fracture by FRAX score and femoral neck bone mineral density: the Fracture Intervention Trial

The WHO Fracture Risk Assessment Tool (FRAX; http://www.shef.ac.uk/FRAX) estimates the 10-year probability of major osteoporotic fracture. Clodronate and bazedoxifene reduced nonvertebral and clinical fracture more effectively on a relative scale in women with higher FRAX scores. We used data from the Fracture Intervention Trial (FIT) to evaluate the interaction between FRAX score and treatment with alendronate. We combined the Clinical Fracture (CF) arm and Vertebral Fracture (VF) arm of FIT. The CF and VF arm of FIT randomized 4432 and 2027 women, respectively, to placebo or alendronate for 4 and 3 years, respectively. FRAX risk factors were assessed at baseline. FRAX scores were calculated by WHO. We used Poisson regression models to assess the interaction between alendronate and FRAX score on the risk of nonvertebral, clinical, major osteoporotic, and radiographic vertebral fractures. Overall, alendronate significantly reduced the risk of nonvertebral fracture (incidence rate ratio [IRR] 0.86; 95% confidence interval [CI], 0.75-0.99), but the effect was greater for femoral neck (FN) bone mineral density (BMD) T-score ≤ -2.5 (IRR 0.76; 95% CI, 0.62-0.93) than for FN T-score > -2.5 (IRR 0.96; 95% CI, 0.80-1.16) (p = 0.02, interaction between alendronate and FN BMD). However, there was no evidence of an interaction between alendronate and FRAX score with FN BMD for risk of nonvertebral fracture (interaction p = 0.61). The absolute benefit of alendronate was greatest among women with highest FRAX scores. Results were similar for clinical fractures, major osteoporotic fractures, and radiographic vertebral fractures and whether or not FRAX scores included FN BMD. Among this cohort of women with low bone mass there was no significant interaction between FRAX score and alendronate for nonvertebral, clinical or major osteoporotic fractures, or radiographic vertebral fractures. These results suggest that the effect of alendronate on a relative scale does not vary by FRAX score. A randomized controlled trial testing the effect of antifracture agents among women with high FRAX score but without osteoporosis is warranted.

Efficacy of antiresorptive agents for preventing fractures in Japanese patients with an increased fracture risk: review of the literature

The aim of the present review was to clarify the efficacy of currently available potent antiresorptive agents for preventing fractures in Japanese patients with an increased fracture risk. PubMed was used to search the literature for randomized controlled trials (RCTs), with the following search terms: fracture, etidronate, alendronate, risedronate, minodronate, raloxifene, bazedoxifene and Japan. The inclusion criteria were papers written in English, ≥50 subjects per group and a study period of ≥1 year. Fourteen RCTs met these criteria. The efficacy of antiresorptive agents for preventing vertebral, nonvertebral and hip fractures was investigated. There was evidence that raloxifene reduced the incidence of clinical vertebral fractures, while etidronate, alendronate and minodronate (but not bazedoxifene) reduced the incidence of morphometric vertebral fractures in patients with postmenopausal or involutional osteoporosis. Head-to-head trials showed that alendronate and raloxifene had similar efficacy for preventing vertebral fractures in patients with postmenopausal osteoporosis, while risedronate was not inferior to etidronate for reducing the incidence of morphometric vertebral fractures in patients with involutional osteoporosis. Alendronate reduced the incidence of hip fractures in patients with Parkinson's disease, and risedronate reduced the incidence of nonvertebral fractures and hip fractures in patients with Alzheimer's disease or stroke. In conclusion, the present review confirmed the efficacy of etidronate, minodronate and raloxifene for the prevention of vertebral fractures, the efficacy of alendronate for vertebral and hip fractures, and the efficacy of risedronate for vertebral, nonvertebral and hip fractures in Japanese patients with an increased fracture risk.

Targeted approaches in the treatment of osteoporosis: differential mechanism of action of denosumab and clinical utility

Denosumab is a breakthrough biological drug approved by the Food and Drug Administration and European Medicines Agency for the treatment of osteoporosis in 2010. It is a fully human monoclonal antireceptor activator of nuclear factor kappa-B ligand antibody, which inhibits the activity of osteoclasts, resulting in an antiresorptive effect with a significant increase in bone mineral density. The FREEDOM (Fracture Reduction Evaluation of Denosumab in Osteoporosis every 6 Months) trial, comparing denosumab with no treatment in 7868 women with postmenopausal osteoporosis, showed an important reduction of fracture risk at hip, vertebral, and nonvertebral sites in the treated group, while no statistically significant difference in the incidence of adverse events was detected between denosumab and placebo groups. The specific action of denosumab directed against a key regulator of osteoclasts makes it a valuable tool in preventing the occurrence of skeletal events caused by bone destruction in patients with advanced malignancies. The drug was approved for postmenopausal osteoporosis in women at increased risk of fracture and for the treatment of bone loss associated with androgen deprivation therapy in men with prostate cancer.

Breast cancer incidence in postmenopausal women with osteoporosis or low bone mass using arzoxifene

The Generations trial, a multicenter, placebo-controlled, double-blind trial, compared arzoxifene 20 mg/day and placebo in 9,354 postmenopausal women with osteoporosis (N=5,252) or low bone mass (N=4,102). Primary outcomes were vertebral fracture in the osteoporotic population and invasive breast cancer in all study participants. Here, we report the detailed breast cancer findings from the trial. Breast cancers were detected by annual mammograms and clinical examination. After 48 months follow-up, breast cancer incidence was compared between treatment groups by estrogen receptor (ER) and progesterone receptor (PR) status and baseline risk factors. Baseline breast cancer risk factors, including age, estimated Gail risk, and bone mineral density, were well balanced between treatment groups. A total of 75 breast cancers occurred 53 in the placebo group and 22 in the arzoxifene group (HR 0.41, 95% CI 0.25-0.68, P<0.001). There were 62 invasive breast cancers, 39 identified as invasive ER-positive (placebo 30, arzoxifene 9; HR 0.30, 95% CI 0.14-0.63, P=0.001) and 30 identified as invasive PR-positive (placebo 23, arzoxifene 7; HR 0.30, 95% CI 0.13-0.71, P=0.003). Breast cancer risk reduction with arzoxifene was similar between Gail risk groups (P interaction=0.31) and between low bone mass and osteoporosis groups (P interaction=0.35). Although generally well tolerated, there was a significant increase in venous thromboembolism, vasomotor symptoms, muscle cramps, and some gynecological events with arzoxifene. These findings demonstrate that in this study arzoxifene reduced the risk of ER-positive breast cancer in this population of postmenopausal women with low bone mass or osteoporosis, an effect similar to that seen with other SERMs.

Risk factors for prediction of inadequate response to antiresorptives

Some patients sustain fractures while on antiresorptives. Whether this represents an inadequate response (IR) to treatment or a chance event has not been elucidated. We performed a study to identify which patients are more likely to fracture while on treatment. This is a multicentric, cross-sectional study of postmenopausal women on antiresorptives for osteoporosis in 12 Spanish hospitals, classified as adequate responders (ARs) if on treatment with antiresorptives for 5 years with no incident fractures or inadequate responders (IRs) if an incident fracture occurred between 1 and 5 years on treatment. Poor compliance, secondary osteoporosis, and previous anti-osteoporosis treatment other than the assessed were exclusion criteria. Clinical, demographic, analytical, dual-energy X-ray absorptiometry (DXA) variables, and proximal femur structure analysis (ImaTx™) and structural/fractal analyses of distal radius were performed. A total of 179 women (76 IRs; mean (SD): age 68.2 (9.0) years; 103 ARs, age 68.5 (7.9) years) were included. History of prior fracture (p = 0.005), two or more falls in the previous year (p = 0.032), low lumbar spine bone mineral density (BMD) (p = 0.02), 25 hydroxyvitamin D (p = 0.017), and hip ImaTx fracture load index (p = 0.004) were associated with IR. In the logistic regression models a fracture before treatment (odds ratio [OR], 3.60; 95% confidence interval [CI], 1.47-8.82; p = 0.005) and levels of 25 hydroxyvitamin D below 20 ng/mL (OR, 3.89; 95% CI, 1.55-9.77; p = 0.004) significantly increased risk for IR, while increased ImaTx fracture load (OR, 0.96; 95% CI, 0.93-0.99; p = 0.006; per every 100 units) was protective, although the latter became not significant when all three variables were fitted into the model. Therefore, we can infer that severity of the disease, with microarchitectural and structure deterioration, as shown by previous fracture and hip analysis, and low levels of 25 hydroxy vitamin D carry higher risk of inadequate response to antiresorptives. More potent regimes should be developed and adequate supplementation implemented to solve this problem.

Individualizing osteoporosis therapy

Guidelines for osteoporosis treatment are available; however, these guidelines suggest when to treat patients, without specific recommendations on what drugs to prescribe in various situations. Choice of osteoporosis therapy should be individualized based on consideration of the efficacy, safety, cost, convenience (i.e., dosing regimen and delivery), and other non-osteoporosis-related benefits associated with each agent. Bisphosphonates, administered orally or intravenously, should be considered first-line therapy, particularly in older patients, owing to their efficacy across multiple skeletal sites; however, there are potential short- and long-term safety concerns. Selective estrogen receptor modulators should be considered for younger postmenopausal women at greater risk for vertebral than hip fractures or as second-line therapy in women who cannot tolerate first-line therapies. Low-dose hormone therapy may be appropriate as prevention in women with menopausal symptoms at lower fracture risk. Calcitonin, with its relatively benign safety profile, may be appropriate for elderly women who may have difficulty following the complex dosing schedules of oral bisphosphonates. Anabolic therapies such as teriparatide should be considered for high-risk patients. Strontium ranelate (approved outside of North America), with both anabolic and antiresorptive properties, may be appropriate for women who cannot tolerate or are unable to take bisphosphonates. Denosumab is a monoclonal antibody appropriate for women at high fracture risk or who have failed other osteoporosis therapies, and may be considered in patients with renal insufficiency. It will be important to incorporate newer agents (e.g., bazedoxifene, tissue selective estrogen complex) into this individualized treatment paradigm to optimize clinical outcomes in patients with osteoporosis.

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.

Long-term treatment of osteoporosis in postmenopausal women: a review from the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO) and the International Osteoporosis Foundation (IOF)

INTRODUCTION

Postmenopausal osteoporosis is a chronic disease requiring treatment that balances long-term fracture efficacy against risk.

METHODS

We reviewed the efficacy and safety of calcium and vitamin D, the selective estrogen receptor modulators (SERMs), the bisphosphonates, denosumab, and strontium ranelate in studies of 3 years or longer.

RESULTS

Six trials lasted for 5 years, and seven went beyond that. The evidence beyond 5 years is generally weak, mainly due to methodological issues (open-label design, small samples, or absence of placebo control). Although calcium and vitamin D appear to be beneficial, the data are insufficient to evaluate benefits and risk beyond 3 years. The fracture efficacy of SERMs beyond 5 years is not known, though increases in bone mineral density (BMD) appear to be maintained. The SERMs have good long-term safety, including protective effects against breast cancer. The bisphosphonates have established fracture efficacy to 3 years, and 4 or 5 years with alendronate and risedronate. The evidence beyond 5 years indicates sustained increases in BMD. The safety of the bisphosphonates does not appear to be modified with time, with the possible exceptions of atypical subtrochanteric fracture and other events of unknown frequency. Denosumab has been tested up to 5 years, with continued increased in BMD and no reported safety issues. There is evidence for fracture efficacy of strontium ranelate, and sustained increases in BMD over 10 years. Strontium ranelate has good long-term safety.

CONCLUSION

Robust long-term studies are relatively rare for the osteoporosis treatments, and generally show maintenance of BMD and, for some agents, an additional reduction in fracture incidence.

Tissue-Specific Effects of Loss of Estrogen during Menopause and Aging

The roles of estrogens have been best studied in the breast, breast cancers, and in the female reproductive tract. However, estrogens have important functions in almost every tissue in the body. Recent clinical trials such as the Women's Health Initiative have highlighted both the importance of estrogens and how little we know about the molecular mechanism of estrogens in these other tissues. In this review, we illustrate the diverse functions of estrogens in the bone, adipose tissue, skin, hair, brain, skeletal muscle and cardiovascular system, and how the loss of estrogens during aging affects these tissues. Early transcriptional targets of estrogen are reviewed in each tissue. We also describe the tissue-specific effects of selective estrogen receptor modulators (SERMs) used for the treatment of breast cancers and postmenopausal symptoms.

Bazedoxifene: a review of its use in the treatment of postmenopausal osteoporosis

Bazedoxifene (Conbriza®, Viviant®) is the first third-generation selective estrogen receptor modulator (SERM) and it is approved for the treatment of postmenopausal osteoporosis in the EU and Japan. Bazedoxifene contains an indole-based core binding domain that binds with high affinity to estrogen receptors and exhibits favourable effects on bone and lipid profiles, with no clinically relevant endometrial or breast stimulation. Oral bazedoxifene once daily reduced the incidence of new vertebral fractures in patients with postmenopausal osteoporosis in a large, well designed trial of 3 years' duration; both bazedoxifene and raloxifene were significantly more effective than placebo. Neither bazedoxifene nor raloxifene reduced the incidence of nonvertebral fractures in the overall study population; however, bazedoxifene, but not raloxifene, reduced the rate of nonvertebral fractures in high-risk patients. Moreover, data from patients who continued to receive the drug during a 2-year extension phase of this trial indicate that bazedoxifene continues to provide protection against new vertebral fractures for up to 5 years. Bazedoxifene also increases bone mineral density and reduces the levels of bone turnover markers. Bazedoxifene was generally well tolerated and did not detrimentally affect the reproductive tract or breast tissue in clinical trials, thereby demonstrating a favourable risk-benefit profile. A pharmacoeconomic analysis conducted from an EU perspective predicted bazedoxifene to be cost effective in some EU countries. Therefore, bazedoxifene presents another useful option for the treatment of postmenopausal osteoporosis, especially in those at high risk for osteoporotic fracture.

Effect of denosumab treatment on the risk of fractures in subgroups of women with postmenopausal osteoporosis

Denosumab reduces the risk of new vertebral and nonvertebral fractures. Previous trials suggest that the efficacy of antiresorptives on fractures might differ by patients' characteristics, such as age, bone mineral density (BMD), and fracture history. In the FREEDOM study, 7808 women aged 60 to 90 years with osteoporosis were randomly assigned to receive subcutaneous injections of denosumab (60 mg) or placebo every 6 months for 3 years. New vertebral and nonvertebral fractures were radiologically confirmed. Subgroup analyses described in this article were prospectively planned before study unblinding to evaluate the effect of denosumab on new vertebral and nonvertebral fractures across various subgroups. Compared with placebo, denosumab decreased the risk of new vertebral fractures in the overall study population over 3 years. This effect did not significantly differ for any of the nine subgroups analyzed (p > 0.09 for all potential interactions). Denosumab also reduced all nonvertebral fractures by 20% in the full study cohort over 3 years. This risk reduction was statistically significant in women with a baseline femoral neck BMD T-score ≤ -2.5 but not in those with a T-score > -2.5; in those with a body mass index (BMI) < 25 kg/m(2) but not ≥ 25 kg/m(2); and in those without but not with a prevalent vertebral fracture. These differential treatment effects were not explained by differences in BMD responses to denosumab. Denosumab 60 mg administered every 6 months for 3 years in women with osteoporosis reduced the risk of new vertebral fractures to a similar degree in all subgroups. The effect of denosumab on nonvertebral fracture risk differed by femoral neck BMD, BMI, and prevalent vertebral fracture at baseline.

Sustained efficacy and safety of bazedoxifene in preventing fractures in postmenopausal women with osteoporosis: results of a 5-year, randomized, placebo-controlled study

In this 2-year extension of a 3-year study, bazedoxifene showed sustained efficacy in preventing new vertebral fractures in postmenopausal women with osteoporosis and in preventing non-vertebral fractures in higher-risk women. Bazedoxifene significantly increased bone mineral density and reduced bone turnover versus placebo and was generally safe and well tolerated.

INTRODUCTION

This study evaluated the efficacy and safety of bazedoxifene for the treatment of postmenopausal osteoporosis over 5 years.

METHODS

A total of 4,216 postmenopausal women with osteoporosis were enrolled in this 2-year extension of a 3-year, randomized, double-blind, placebo-controlled, phase 3 trial. In the core study (N = 7,492), subjects received bazedoxifene 20 or 40 mg/day, raloxifene 60 mg/day, or placebo. The raloxifene arm was discontinued after 3 years; subjects receiving bazedoxifene 40 mg were transitioned to bazedoxifene 20 mg after 4 years. Five-year findings are reported for bazedoxifene 20 and 40/20 mg and placebo. Endpoints included incidence of new vertebral fractures (primary) and non-vertebral fractures, and changes in bone mineral density (BMD) and bone turnover markers.

RESULTS

At 5 years, the incidence of new vertebral fractures in the intent-to-treat population was significantly lower with bazedoxifene 20 mg (4.5%) and 40/20 mg (3.9%) versus placebo (6.8%; P < 0.05), with relative risk reductions of 35% and 40%, respectively. Non-vertebral fracture incidence was similar among groups. In a subgroup of higher-risk women (n = 1,324; femoral neck T-score ≤-3.0 and/or ≥ 1 moderate or severe or ≥ 2 mild vertebral fracture[s]), bazedoxifene 20 mg reduced non-vertebral fracture risk versus placebo (37%; P = 0.06); combined data for bazedoxifene 20 and 40/20 mg reached statistical significance (34% reduction; P < 0.05). Bazedoxifene significantly increased BMD and reduced bone turnover versus placebo (P < 0.05) and was generally safe and well tolerated.

CONCLUSIONS

The findings support a sustained anti-fracture effect of bazedoxifene on new vertebral fractures in postmenopausal osteoporotic women and on non-vertebral fractures in the higher-risk subgroup of women.