Comparing raloxifene with continuous combined estrogen-progestin therapy in postmenopausal women: Review of Euralox 1

Selective Estrogen Receptor Modulators in Gynecology Practice

Selective estrogen receptor (ER) modulators have variable tissue specific estrogen agonist and antagonist activities. Tamoxifen is approved for treatment and prevention of breast cancer; acts as an endometrial estrogen agonist. Raloxifene is approved for prevention and treatment of osteoporosis and prevention of breast cancer. The selective ER modulators bazedoxifene paired with conjugated estrogens relieves vasomotor symptoms and prevents bone loss with neutral effects on breast and amenorrhea similar to placebo. Ospemifene is approved to treat dyspareunia. Lasofoxifene is in development for resistant ER positive breast cancer. Estetrol (E4), synthesized by human fetal liver, has dual weak-estrogenic/antiestrogenic features, now approved as a contraceptive.

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

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

Relative effects of tamoxifen, raloxifene, and conjugated equine estrogens on cognition

OBJECTIVE

To compare the relative effects of conjugated equine estrogens (CEE), raloxifene, and tamoxifen therapies on cognition among women aged > or =65 years.

METHODS

Annual Modified Mini-Mental State (3MS) examinations were used to assess global cognitive function in the two randomized placebo-controlled clinical trials of CEE therapies of the Women's Health Initiative Memory Study (WHIMS) and the Cognition in the Study of Tamoxifen and Raloxifene (CoSTAR). Analyses were limited to women who had 3MS testing at baseline and the first 3 years of follow-up and, because of potential ethnic-related differences between studies, to Caucasian women (WHIMS n = 6211, CoSTAR n = 250). Covariate adjustment was used to compare the postrandomization mean 3MS scores among the three active therapies with placebo therapy while controlling for differences between groups with respect to dementia risk factors.

RESULTS

At baseline, the average (SD) 3MS scores by group were 95.24 (4.28) for placebo, 95.19 (4.33) for CEE, 94.60 (4.76) for raloxifene, and 95.02 (4.03) for tamoxifen. Compared with placebo, each active therapy was associated with a small mean relative deficit in 3MS scores of < or =0.5 units, which was fairly consistent between women with and without prior hysterectomy. Relative deficits were slightly greater for tamoxifen (p = 0.001) and less marked for raloxifene (p = 0.06) and CEE (p = 0.02) therapies. Relative deficits appeared to be greater among women with lower baseline 3MS scores: p = 0.009 (tamoxifen), p = 0.08 (raloxifene), and p = 0.03 (CEE).

CONCLUSIONS

Although unmeasured differences between trials may have confounded analyses, these findings raise the possibility that both tamoxifen and raloxifene adversely affect cognitive function in older women; however, the magnitude of the effect is small, and the long-term consequences are unknown.

An old friend in a new light: the role of osteocalcin in energy metabolism

Accumulating evidence suggests interactions between bone and energy metabolism, which may affect the risk of cardiovascular disease. Recent animal studies indicate that osteocalcin (OC) plays a key role in the coordinated regulation of glucose and insulin metabolism while insulin receptors on osteoblasts may regulate bone turnover and circulating OC levels. Association studies, weight loss interventions, and observational data lend some support to the existence and relevance of these mechanisms in humans. However, corroborating evidence from pharmacologic interventions in either bone or glucose metabolism is limited by the number, design, and complex pharmacological effects of the drugs used. Furthermore, such clinical trials are complicated by the alteration of metabolic feedback mechanisms in the insulin resistant state. Purpose-designed studies are needed to further establish the existence and significance of the role of OC and its subfractions in human insulin metabolism. In this review we summarize existing animal evidence regarding the role of OC and its subfractions in bone and energy metabolism and assess current clinical trial evidence relating to the significance and consequences of this relationship in humans.

SERMs and SERMs with estrogen for postmenopausal osteoporosis

Bone loss with aging places postmenopausal women at a higher risk for osteoporosis and its consequences such as fractures, pain, disability, and increased morbidity and mortality. Approximately 200 million patients worldwide are affected. The Third National Health and Nutrition Examination Survey (NHANES III) estimated that up to 18% of US women aged 50 and older have osteoporosis and up to 50% have osteopenia. Greater than 2 million osteoporotic related fractures occurred in the United States with direct healthcare costs exceeding $17 billion. Hormone Replacement Therapy (HRT) was a popular option for postmenopausal women before the Women's Health Initiative (WHI). Several agents are available in the U.S., including bisphosphonates, hormone therapy, calcitonin, parathyroid hormone and the selective estrogen receptor modulator (SERM) raloxifene. There are concerns about long term safety and compliance. Therefore, other agents are under investigation. SERMs are a diverse group of agents that bind to the estrogen receptor and each SERM appears to have a unique set of clinical responses, which are not always consistent with the typical responses seen with other SERMs. This article will discuss the SERMs approved in the United States, tamoxifene and raloxifene, and investigational SERMs. The ideal SERM would include the beneficial effects of estrogen in bone, heart and the central nervous system, with neutral or antagonistic effects in tissues where estrogen effects are undesirable(breast and endometrium). A new target in treating postmenopausal osteoporosis is the tissue estrogen complex or the pairing of a SERM with a conjugated estrogen known as a tissue selective estrogen complex (TSEC). This novel approach is currently being evaluated with bazodoxifene which could yield the beneficial effects of estrogens and SERMS, while potentially being more tolerable and safer than either therapy alone.

Endometrial hysteroscopic and histological evaluation in menopausal women in continuous use of raloxifene

OBJECTIVE

To study the effect of raloxifene on endometrial histopathology of menopausal women.

METHODS

Thirty-one patients under raloxifene treatment (60 mg/day) for a six-month period and submitted to diagnostic videohysteroscopy at the Climateric Outpatients Clinic, Department of Gynecology and Obstetrics, Hospital do Servidor Público Estadual Francisco Morato de Oliveira, in the city of São Paulo, and at Hospital Guilherme Álvaro, in the city of Santos, from September 10th, 2003 to June 22nd, 2004, were analyzed. Guided endometrial biopsy was performed on all patients on the anterior wall, using a 3-mm or 5-mm biopsy forceps. A 3-mm or 5-mm hysteroscope was used with TV imaging by an endocamera. The results of the hysteroscopic tests were compared before and six months after the use of raloxifene.

RESULTS

The comparison between both biopsies was performed by means of the McNemar's test (marginal homogeneity test), and showed a descriptive level of 0.001 that indicates difference between the estrogen effects assessed at different moments. The estrogen effect on the endometrial tissue did not increase in any of the 31 patients analyzed. Twenty-one patients (68%) showed smaller estrogen effect in the final evaluation.

CONCLUSIONS

The study showed no evidence of endometrial stimulation of raloxifene and, in fact, many women presented less estrogen effect after its use.

American society of clinical oncology clinical practice guideline update on the use of pharmacologic interventions including tamoxifen, raloxifene, and aromatase inhibition for breast cancer risk reduction

PURPOSE To update the 2002 American Society of Clinical Oncology guideline on pharmacologic interventions for breast cancer (BC) risk reduction. METHODS A literature search identified relevant randomized trials published since 2002. Primary outcome of interest was BC incidence (invasive and noninvasive). Secondary outcomes included BC mortality, adverse events, and net health benefits. An expert panel reviewed the literature and developed updated consensus guidelines. Results Seventeen articles met inclusion criteria. In premenopausal women, tamoxifen for 5 years reduces the risk of BC for at least 10 years, particularly estrogen receptor (ER) -positive invasive tumors. Women < or = 50 years of age experience fewer serious side effects. Vascular and vasomotor events do not persist post-treatment across all ages. In postmenopausal women, raloxifene and tamoxifen reduce the risk of ER-positive invasive BC with equal efficacy. Raloxifene is associated with a lower risk of thromboembolic disease, benign uterine conditions, and cataracts than tamoxifen in postmenopausal women. No evidence exists establishing whether a reduction in BC risk from either agent translates into reduced BC mortality. Recommendations In women at increased risk for BC, tamoxifen (20 mg/d for 5 years) may be offered to reduce the risk of invasive ER-positive BC, with benefits for at least 10 years. In postmenopausal women, raloxifene (60 mg/d for 5 years) may also be considered. Use of aromatase inhibitors, fenretinide, or other selective estrogen receptor modulators to lower BC risk is not recommended outside of a clinical trial. Discussion of risks and benefits of preventive agents by health providers is critical to patient decision making.

Effects of tamoxifen and raloxifene on normal human endometrial cells in an organotypic in vitro model

The selective estrogen receptor modulator tamoxifen is widely used in breast cancer therapy though its use is associated with an elevated risk of endometrial carcinoma. An organotypic culture model was employed here to examine the effects of tamoxifen and raloxifene, a related compound with no known adverse uterine effects, on epithelial cells of the premenopausal human endometrium. Changes in the expression levels of the proliferation marker Ki67, and estrogen and progesterone receptors were evaluated. No change in the Ki67 index compared to untreated controls was detected in cultures exposed to tamoxifen or tamoxifen+estradiol. In response to tamoxifen, the level of progesterone receptor-expressing organoids was shown to vary markedly between individual samples, whereas no change in estrogen receptor expression could be demonstrated. A significant decrease in Ki67 expression was observed in raloxifene-exposed cultures. Raloxifene or raloxifene+estradiol had no effect on progesterone receptor expression. The expression of estrogen receptor was markedly inhibited in response to raloxifene or raloxifene+estradiol in all but two samples displaying an intense estrogen receptor labelling. The present observations add to current clinical data on the respective estrogen receptor agonist and antagonist activities of tamoxifen and raloxifene on the human uterus by providing novel insights into the interindividual variation in cellular responses. Our organotypic model may have uses as an alternative to animal experimentation in preclinical screening of the endometrial effects of selective estrogen receptor modulators and may serve as a tool in personalized medicine by identifying patients with an increased risk of developing endometrial pathologies.

Selective estrogen receptor modulators: an update on recent clinical findings

Recent clinical data on selective estrogen receptor modulators (SERMs) have provided the basis for reassessment of the SERM concept. The molecular basis of SERM activity involves binding of the ligand SERM to the estrogen receptor (ER), causing conformational changes which facilitate interactions with coactivator or corepressor proteins, and subsequently initiate or suppress transcription of target genes. SERM activity is intrinsic to each ER ligand, which accomplishes its unique profile by specific interactions in the target cell, leading to tissue selective actions. We discuss the estrogenic and anti-estrogenic effects of early SERMs, such as clomiphene citrate, used for treatment of ovulation induction, and the triphenylethylene, tamoxifen, which has ER antagonist activity in the breast, and is used for prevention and treatment of ER-positive breast cancer. Since the development of tamoxifen, other triphenylethylene SERMs have been studied for breast cancer prevention, including droloxifene, idoxifene, toremifene, and ospemifene. Other SERMs have entered clinical development more recently, including benzothiophenes (raloxifene and arzoxifene), benzopyrans (ormeloxifene, levormeloxifene, and EM-800), lasofoxifene, pipendoxifene, bazedoxifene, HMR-3339, and fulvestrant, an anti-estrogen which is approved for breast cancer treatment. SERMs have effects on tissues containing ER, such as the breast, bone, uterine and genitourinary tissues, and brain, and on markers of cardiovascular risk. Current evidence indicates that each SERM has a unique array of clinical activities. Differences in the patterns of action of SERMs suggest that each clinical end point must be evaluated individually, and conclusions about any particular SERM can only be established through appropriate clinical trials.

Ultrasound appearance of the uterus in women over 60 years of age on tibolone: is it a SERM?

OBJECTIVES

To evaluate the effects of long-term tibolone on the endometria of asymptomatic women over the age of 60 years.

METHODS

An observational study of the ultrasound appearance of the endometria of women aged 60 years or older taking long-term tibolone. Those found to have a double-layer endometrial thickness greater than 4 mm were offered endometrial biopsy.

RESULTS

Seventeen asymptomatic patients with a mean age of 61 years (range 60-73 years) and an average duration of tibolone use of 5 years (range 3-12 years) were recruited. Seven patients (41%) showed a thickened endometrium of more than 4 mm. Three of these had an area of translucency in the subendometrial space. Of the ten women with an endometrial thickness of less than 4 mm, four showed the presence of subendometrial fluid. Hysteroscopy was performed in five out of the seven women, as two did not accept further investigations. In all five women, the endometrial cavity was reported as atrophic and the histology showed an inactive basal type. In two of the five cases examined histologically, there were additional changes suggesting endometrial polyp, although the samples were from macroscopically non-polypoid endometrium.

DISCUSSION

Endometrial thickness is increased in 41% of elderly women on long-term treatment with tibolone. However, at hysteroscopy, the endometrium was uniformly atrophic. Similar finding have been described in women using selective estrogen receptor modulators and a similar mechanism of action of these drugs on the uterus should be considered.

Skeletal pain in postmenopausal women with osteoporosis: prevalence and course during raloxifene treatment in a prospective observational study of 6 months duration

OBJECTIVE

To assess the prevalence of skeletal pain in postmenopausal women before the onset of raloxifene treatment and the further course of pain during treatment in a naturalistic setting.

RESEARCH DESIGN AND METHODS

Prospective, uncontrolled, multicentre, 6-month, observational study in Germany. Clinical, diagnostic and pain data were collected at baseline, 6 weeks and 6 months of raloxifene treatment from 3299 female outpatients with postmenopausal osteoporosis. Physicians assessed the presence or absence of back pain, joint pain and diffuse bone pain at each visit, perceived sleep quality and the use of analgesics. Patients assessed intensity and frequency of pain using a 100 mm visual analogue scale (VAS) and a 5-point scale (from 'rarely' to 'permanently'), respectively.

RESULTS

At baseline, patients had mean (SD) age 67.6 (9.3) years, 89.4% were reported to have reduced bone mineral density, 39.8% had pre-existing fractures and 93.4% had skeletal pain (physician assessment): 85.1% had back pain, 41.8% joint pain and 32.5% diffuse bone pain. Median pain intensity on VAS was 66.0 mm. After 6 months of raloxifene treatment, the frequency and intensity of pain and use of analgesics for skeletal pain decreased consistently by approximately 50%. Pain frequency decreased in 58.2% and increased in 2.3% of patients. The median decrease in pain intensity from baseline to 6 months was 27.0 mm (46%). Patients' subjective quality of sleep improved: the proportion of patients who were reported to sleep well increased from 21.3% at baseline to 46.7% at 6 months. The decrease in relative pain frequency was greatest with diffuse pain (67.6%) followed by joint pain (36.9%) and back pain (32.5%).

CONCLUSION

Raloxifene treatment in postmenopausal women with osteoporosis was associated with a marked reduction of skeletal pain and analgesic consumption and an improvement in subjective sleep quality. Further investigation in a randomised, placebo-controlled trial is warranted.