ospemifene and Osteoporosis

Ospemifene is an estrogen-receptor agonist/antagonist (also known as a selective estrogen-receptor modulator) that is FDA approved for the treatment of moderate-to-severe dyspareunia, a symptom of vulvovaginal atrophy, due to menopause. Preclinical and clinical data suggest that ospemifene may also have an effect on bone health in postmenopausal women.. Relevant articles, including cellular and preclinical studies and clinical trials written in English pertaining to ospemifene and bone health, were identified from a database search of PubMed (from its inception to June 2015) and summarized in this comprehensive review.. In vitro data suggest that ospemifene may mediate a positive effect on bone through osteoblasts. Ospemifene effectively reduced bone loss and resorption in ovariectomized rats, with activity comparable to estradiol and raloxifene. Clinical data from three phase 1 or 2 clinical trials (2 placebo- and 1 raloxifene-controlled) found ospemifene 60 mg/d to have a positive effect on the biochemical markers for bone turnover in healthy, postmenopausal women with significant improvements relative to placebo and comparable to raloxifene.. Ospemifene 60 mg/d may have a protective effect on the bone health of women being treated for dyspareunia. The initial clinical data for ospemifene follows a trend similar to raloxifene and bazedoxifene, suggesting that ospemifene may have bone-protective effects in postmenopausal women. However, additional rigorous clinical trials are necessary to confirm any positive effects ospemifene may have on vertebral fractures and bone mineral density in healthy and osteoporotic women.

Topics: Animals; Bone and Bones; Bone Density; Bone Remodeling; Bone Resorption; Controlled Clinical Trials as Topic; Dyspareunia; Female; Humans; Osteoblasts; Osteoclasts; Osteoporosis; Ovariectomy; Postmenopause; Rats; Selective Estrogen Receptor Modulators; Tamoxifen

Traditional menopausal hormone therapy containing estrogens/progestin has been associated with an increased risk of breast cancer, and estrogen exposure is known to promote growth and proliferation of a majority of breast cancers. Therefore, it is important for clinicians to consider the breast safety profile of any hormone-based therapy used in postmenopausal women. This review provides an overview of the breast safety and tolerability profiles of currently marketed selective estrogen receptor modulators, antiestrogens, and the first tissue selective estrogen complex combining conjugated estrogens with the selective estrogen receptor modulator bazedoxifene in postmenopausal women. Selective estrogen receptor modulators and antiestrogens act as estrogen receptor antagonists in the breast. Tamoxifen, toremifene, and the selective estrogen receptor degrader fulvestrant are used to treat breast cancer, and tamoxifen and raloxifene protect against breast cancer in high-risk women. Postmenopausal women using selective estrogen receptor modulators for prevention or treatment of osteoporosis (raloxifene, bazedoxifene) can be reassured that these hormonal treatments do not adversely affect their risk of breast cancer and may, in the case of raloxifene, even be protective. There are limited data on breast cancer in women who use ospemifene for dyspareunia. Conjugated estrogens/bazedoxifene use for up to two years did not increase mammographic breast density or breast pain/tenderness, and there was no evidence of an increased risk of breast cancer, suggesting that conjugated estrogens/bazedoxifene has an improved breast safety profile compared with traditional menopausal hormone therapies. Future research will continue to focus on development of selective estrogen receptor modulators and selective estrogen receptor modulator combinations capable of achieving the ideal balance of estrogen receptor agonist and antagonist effects.

Topics: Animals; Breast; Breast Neoplasms; Drug Therapy, Combination; Estradiol; Estrogen Antagonists; Estrogens; Estrogens, Conjugated (USP); Female; Fulvestrant; Humans; Indoles; Osteoporosis; Postmenopause; Protective Factors; Raloxifene Hydrochloride; Risk Assessment; Selective Estrogen Receptor Modulators; Tamoxifen; Toremifene

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

Topics: Breast Neoplasms; Clinical Trials as Topic; Dyspareunia; Estrogens, Conjugated (USP); Female; Hot Flashes; Humans; Indoles; Osteoporosis; Osteoporosis, Postmenopausal; Postmenopause; Pyrrolidines; Raloxifene Hydrochloride; Receptors, Estrogen; Selective Estrogen Receptor Modulators; Tamoxifen; Tetrahydronaphthalenes; Toremifene

Hormos Medical is developing the selective estrogen receptor modulator ospemifene, for the potential treatment of postmenopausal osteoporosis and urogenital atrophy. By November 2003, Hormos had advanced the drug into phase II/III testing for both indications.

Topics: Animals; Clinical Trials as Topic; Estrogen Receptor Modulators; Humans; Hypolipidemic Agents; Osteoporosis; Structure-Activity Relationship; Tamoxifen

FC1271a is a novel triphenylethylene compound with a tissue-selective profile of estrogen agonistic and weak antagonistic effects. It specifically binds to the estrogen receptor alpha and beta with affinity closely similar to that of toremifene and tamoxifen. To study the in vivo effects of the compound, 4-month-old rats were sham operated (sham) or ovariectomized (OVX) and treated daily for 4 weeks with various doses of FC1271a or vehicle (orally). FC1271a was able to oppose OVX-induced bone loss by maintaining the trabecular bone volume of the distal femur. Accordingly, the OVX-induced loss of bone strength was prevented at doses of 1 and 10 mg/kg. FC1271a also prevented the OVX-induced increase in serum cholesterol in a dose-dependent manner. No significant changes in uterine wet weight or morphology were observed in the OVX-rats treated with 0.1 or 1 mg/kg FC1271a, but at a dose of 10 mg/kg it had a slightly estrogenic effect. In immature rats the effect of FC1271a on uterine wet weight was less stimulatory than that of toremifene or tamoxifen, but more stimulatory than that of raloxifene or droloxifene. The appearance of the dimethylbenzanthracene (DMBA)-induced mammary tumors was inhibited by treatment of DMBA-treated rats with FC1271a in a dose-dependent manner. In human MCF-7 breast cancer cell tumors raised in nude mice in the presence of estrogen, the growth and expression of pS2 marker gene could not be maintained after estrogen withdrawal by treatment with FC1271a. No formation of DNA adducts was observed in the liver of the FC1271a-treated rats. In conclusion, the bone-sparing, antitumor, and cholesterol-lowering effects of FC1271a combined with a low uterotropic activity and lack of liver toxicity indicate that FC1271a could be an important alternative in planning antiosteoporosis therapy for estrogen deficiency.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Bone and Bones; Breast Neoplasms; Cholesterol; Estrogen Antagonists; Female; Humans; Mammary Neoplasms, Experimental; Mice; Mice, Nude; Organ Size; Osteoporosis; Ovariectomy; Raloxifene Hydrochloride; Rats; Rats, Sprague-Dawley; Reference Values; Tamoxifen; Toremifene; Transplantation, Heterologous; Tumor Cells, Cultured; Uterus