piperidines and bazedoxifene

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. The evidence that tamoxifen significantly increased the risk of endometrial cancer as compared to placebo made this tissue the center of interest in developing new SERMs. Thus, ospemifen, arzoxifene, lasofoxifene (LFX) and bazedoxifene (BZA) appeared as third-generation SERMs but only BZA reached the stage of clinical use. Both experimental and clinical data available on the effects of RLX or third-generation SERMs reaching clinical stage (LFX and BZA) show either neutrality or anti-estrogenic effects at endometrial level. BZA has shown to be equivalent to vehicle in several experimental conditions and acts as anti-estrogen in models were estrogens (conjugated equine estrogens [CEE] or E2) were co-administered. In a 7 years pivotal study the incidence of endometrial adenocarcinoma has been significantly lower in the BZA than in the placebo group. Moreover, in a clinical trial to evaluate the ability of a combination of BZA and CEE to prevent hot flushes in symptomatic postmenopausal women, doses of 20mg or higher of BZA have significantly decreased the risk of presenting endometrial hyperplasia when co-administered with either 0.650 or 0.450mg of CEE.

Topics: Adenocarcinoma; Animals; Breast Neoplasms; Clinical Trials as Topic; Double-Blind Method; Drug Evaluation, Preclinical; Endometrial Neoplasms; Endometrium; Estradiol; Estrogen Replacement Therapy; Estrogens, Conjugated (USP); Female; Hot Flashes; Humans; Indoles; Menopause; Multicenter Studies as Topic; Organ Specificity; Osteoporosis, Postmenopausal; Piperidines; Pyrrolidines; Rats; Selective Estrogen Receptor Modulators; Tamoxifen; Tetrahydronaphthalenes; Thiophenes; Thromboembolism

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

Topics: Bone Density Conservation Agents; Breast; Endometrium; Female; Fractures, Bone; Humans; Indoles; Osteoporosis, Postmenopausal; Piperidines; Pyrrolidines; Selective Estrogen Receptor Modulators; Tamoxifen; Tetrahydronaphthalenes; Thiophenes

Selective estrogen receptor modulators (SERMs) or estrogen agonists/antagonists have shown promise in osteoporosis in that they have the potential to reduce the risk of fracture, and also reduce the risk of breast cancer. SERMs maybe classified according to their core structure, which is typically a variation of the 17 beta-estradiol template and subclassified according to the side chain at the helix 12 affector region. The best known are the triphenylethylenes such as tamoxifen, used in the management of breast cancer. However, the clinical application of this class of SERMs has been limited due to endometrial stimulation. A second class is the benzothiophenes such as raloxifene and arzoxifene, which have skeletal benefit with little, if any, uterine stimulation. Indole-based SERMs such as bazedoxifene have a 2-phenyl ring system that serves as a core binding unit. Other classes include benzopyrans and naphthalenes (eg, lasofoxifene). In this review article, I will discuss raloxifene and three new SERMs--arzoxifene, bazedoxifene, and lasofoxifene--that have been recently studied. I will discuss their effect on bone, breast, and the cardiovascular system, as well as on safety.

Topics: Bone Density Conservation Agents; Breast Neoplasms; Female; Humans; Indoles; Osteoporosis; Piperidines; Pyrrolidines; Risk Factors; Selective Estrogen Receptor Modulators; Tetrahydronaphthalenes; Thiophenes

Postmenopausal osteoporosis is an asymptomatic skeletal disease that is often underdiagnosed and undertreated. Osteoporotic fractures are associated with substantial morbidity and mortality and impaired quality of life-socially, emotionally, and financially. Considering the growing burden of osteoporotic fractures worldwide, there remains an ongoing need for progress in the diagnosis of osteoporosis, identification of individuals at high fracture risk, and treatment to prevent fractures. Adequate intake of calcium and vitamin D is recommended as baseline therapy for osteoporosis prevention and treatment. Available pharmacological agents for the management of postmenopausal osteoporosis may not be appropriate for all women. Oral bisphosphonates are generally considered first-line therapy for patients with osteoporosis, but their use may be limited by gastrointestinal side effects. Other agents include hormone therapy, the selective estrogen receptor modulator (SERM) raloxifene, salmon calcitonin, teriparatide (human recombinant parathyroid hormone), and strontium ranelate (in some countries). Factors that may contribute to poor compliance and persistence with current osteoporosis therapies include drug intolerance, complexity of dosing regimens, and poor understanding of the relative benefit and risk with treatment. Emerging therapies for postmenopausal osteoporosis include novel SERMs (bazedoxifene, lasofoxifene, ospemifene, arzoxifene) and denosumab. Because SERMs can display mixed functional estrogen receptor agonist or antagonist activity depending on the target tissue, they may confer beneficial effects on bone with limited stimulation of other tissues (e.g., breast, endometrium). Clinical investigation of these promising new agents is ongoing to evaluate efficacy and safety, with the goal of developing effective strategies to maximize long-term tolerance, compliance, and persistence with therapy.

Topics: Aged; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Bone Density Conservation Agents; Denosumab; Drug Therapy, Combination; Female; Humans; Indoles; Middle Aged; Osteoporosis, Postmenopausal; Parathyroid Hormone; Piperidines; Postmenopause; Pyrrolidines; Raloxifene Hydrochloride; RANK Ligand; Selective Estrogen Receptor Modulators; Tamoxifen; Tetrahydronaphthalenes; Thiophenes; Vitamin D; Women's Health

Topics: Animals; Bone and Bones; Bone Density; Clinical Trials as Topic; Drug Design; Humans; Indoles; Osteoporosis, Postmenopausal; Piperidines; Pyrrolidines; Rats; Receptors, Estrogen; Research; Selective Estrogen Receptor Modulators; Tetrahydronaphthalenes; Thiophenes

The risk of developing hormone-dependent cancers with long-term exposure to estrogens is attributed both to proliferative, hormonal actions at the estrogen receptor (ER) and to chemical carcinogenesis elicited by genotoxic, oxidative estrogen metabolites. Nontumorigenic MCF-10A human breast epithelial cells are classified as ER(-) and undergo estrogen-induced malignant transformation. Selective estrogen receptor modulators (SERM), in use for breast cancer chemoprevention and for postmenopausal osteoporosis, were observed to inhibit malignant transformation, as measured by anchorage-independent colony growth. This chemopreventive activity was observed to correlate with reduced levels of oxidative estrogen metabolites, cellular reactive oxygen species (ROS), and DNA oxidation. The ability of raloxifene, desmethylarzoxifene (DMA), and bazedoxifene to inhibit this chemical carcinogenesis pathway was not shared by 4-hydroxytamoxifen. Regulation of phase II rather than phase I metabolic enzymes was implicated mechanistically: raloxifene and DMA were observed to upregulate sulfotransferase (SULT 1E1) and glucuronidase (UGT 1A1). The results support upregulation of phase II metabolism in detoxification of catechol estrogen metabolites leading to attenuated ROS formation as a mechanism for inhibition of malignant transformation by a subset of clinically important SERMs.

Topics: Cell Transformation, Neoplastic; Cells, Cultured; Cytoprotection; Estradiol; Humans; Inactivation, Metabolic; Indoles; Mammary Glands, Human; MCF-7 Cells; Oxidants; Oxidative Stress; Piperidines; Raloxifene Hydrochloride; Reactive Oxygen Species; Selective Estrogen Receptor Modulators; Tamoxifen; Thiophenes; Up-Regulation