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

An Update on Tamoxifen and the Chemo-Preventive Potential of Vitamin E in Breast Cancer Management

Breast cancer (BC) is the most common female cancer in terms of incidence and mortality worldwide. Tamoxifen (Nolvadex) is a widely prescribed, oral anti-estrogen drug for the hormonal treatment of estrogen-receptor-positive BC, which represents 70% of all BC subtypes. This review assesses the current knowledge on the molecular pharmacology of tamoxifen in terms of its anticancer and chemo-preventive actions. Due to the importance of vitamin E compounds, which are widely taken as a supplementary dietary component, the review focuses only on the potential importance of vitamin E in BC chemo-prevention. The chemo-preventive and onco-protective effects of tamoxifen combined with the potential effects of vitamin E can alter the anticancer actions of tamoxifen. Therefore, methods involving an individually designed, nutritional intervention for patients with BC warrant further consideration. These data are of great importance for tamoxifen chemo-prevention strategies in future epidemiological studies.

Association of raloxifene and tamoxifen therapy with cognitive performance, odds of mild cognitive impairment, and brain MRI markers of neurodegeneration

The aim of this cross-sectional study was to examine whether a history of selective estrogen receptor modifiers (SERMs), tamoxifen and raloxifene, use was associated with cognitive performance, odds of mild cognitive impairment (MCI), or magnetic resonance imaging (MRI) markers of neurodegeneration associated with Alzheimer's disease. We included women with prior history of breast cancer or no prior history of any cancer at enrollment in the Mayo Clinic Study of Aging (MCSA). This information was abstracted using the Rochester Epidemiology Project medical-linkage system. Logistic regression was used to examine associations of SERMs with odds of MCI. Linear regression models were used to examine associations of SERMs with cognitive z-scores (Memory, Executive Function, Language, Visuospatial Skills, Global Cognition), and MRI markers. Among 2840 women aged 50 and older in the MCSA, 151 had a history of breast cancer, and 42 (28%) of these had a history of tamoxifen treatment. A total of 2235 women had no prior history of any cancer, and 76 (3%) of these had a history of raloxifene use. No significant associations between tamoxifen use and cognition, or odds of MCI were observed among women with a history of breast cancer after adjusting for confounders. Similarly, raloxifene use was not significantly associated with cognition, or odds of MCI in women without a history of cancer after adjusting for confounders. We did not find significant associations between the use of either SERM and MRI markers. Use of tamoxifen or raloxifene was not significantly associated with cognition in postmenopausal women.

Design and baseline characteristics of the cocoa supplement and multivitamin outcomes study for the Mind: COSMOS-Mind

BACKGROUND

Large simple trials are potentially efficient and cost-effective approaches to assess interventions to preserve cognitive function in older adults. High-dose cocoa flavanols supplementation is a promising intervention that warrants additional testing. We describe the design, recruitment success, and baseline characteristics of the Cocoa Supplement and Multivitamin Outcomes Study for the Mind (COSMOS-Mind) trial.

METHODS

COSMOS-Mind is an ancillary study to the large-scale and predominantly mail-based COSMOS randomized controlled clinical trial. COSMOS is assessing whether cocoa extract (including 600 mg/d cocoa flavanols) and a multivitamin reduce risks for major cardiovascular events and total invasive cancer. COSMOS-Mind uses telephone-based interviews to assess cognitive function and impairment to determine whether cocoa flavanols benefit cognitive function in adults aged 65 years or older, targeting the enrollment of 2000 participants to provide >90% statistical power across 3 years of annual follow-up.

RESULTS

Of the 3224 COSMOS screenees who expressed interest in COSMOS-Mind, 2350 (76%) successfully completed baseline cognitive assessments and 2262 (96%) geographically diverse, eligible individuals were ultimately enrolled over one year. At baseline, the primary outcome, a composite of cognitive test scores, was inversely associated with age in a manner consistent with assumptions used in projections of statistical power.

CONCLUSIONS

Older adults are willing to enroll in large simple trials that include telephone-based cognitive assessments. Embedding these trials in large studies of other health outcomes is efficient and expands the scientific knowledge gained from the research. ClinicalTrials.gov Identifiers: NCT03035201 (COSMOS-Mind); NCT102422745 (parent COSMOS).

Hormone therapy at early post-menopause increases cognitive control-related prefrontal activity

Clinical data have been equivocal and controversial as to the benefits to the brain and cognition of hormone therapy (HT) in postmenopausal women. Recent reevaluation of the role of estrogens proposed that HT may effectively prevent the deleterious effects of aging on cognition, and reduces the risks of dementia, including Alzheimer's disease, if initiated early at the beginning of menopause. Yet, little is known about the effects of HT on brain activation related to cognitive control, the ability to make flexible decisions in relation to internal goals. Here, we used fMRI to directly test for a modulation of sequential 17β estradiol (2 mg/day) plus oral progesterone (100 mg/day) on task switching-related brain activity in women at early postmenopause. The results showed that HT enhanced dorsolateral prefrontal cortex recruitment during task switching. Between-subjects correlation analyses revealed that women who engaged more the dorsolateral prefrontal cortex showed higher task switching performance after HT administration. These results suggest that HT, when taken early at the beginning of postmenopause, may have beneficial effect on cognitive control prefrontal mechanisms. Together, these findings demonstrate that HT can prevent the appearance of reduced prefrontal cortex activity, a neurophysiological measure observed both in healthy aging and early dementia.

Tamoxifen induces cellular stress in the nervous system by inhibiting cholesterol synthesis

Background

Tamoxifen (TAM) is an important cancer therapeutic and an experimental tool for effecting genetic recombination using the inducible Cre-Lox technique. Despite its widespread use in the clinic and laboratory, we know little about its effects on the nervous system. This is of significant concern because TAM, via unknown mechanisms, induces cognitive impairment in humans. A hallmark of cellular stress is induction of Activating Transcription Factor 3 (Atf3), and so to determine whether TAM induces cellular stress in the adult nervous system, we generated a knock-in mouse in which Atf3 promoter activity drives transcription of TAM-dependent Cre recombinase (Cre-ERT2); when crossed with tdtomato reporter mice, Atf3 induction results in robust and permanent genetic labeling of cells in which it is up-regulated even transiently.

Results

We found that granular neurons of the olfactory bulb and dentate gyrus, vascular cells and ependymal cells throughout the brain, and peripheral sensory neurons expressed tdtomato in response to TAM treatment. We also show that TAM induced Atf3 up-regulation through inhibition of cholesterol epoxide hydrolase (ChEH): reporter expression was mitigated by delivery in vitamin E-rich wheat germ oil (vitamin E depletes ChEH substrates), and was partially mimicked by a ChEH-specific inhibitor.

Conclusions

This work demonstrates that TAM stresses cells of the adult central and peripheral nervous systems and highlights concerns about clinical and experimental use of TAM. We propose TAM administration in vitamin E-rich vehicles such as wheat germ oil as a simple remedy.

Raloxifene for women with Alzheimer disease: A randomized controlled pilot trial

OBJECTIVE

To determine whether raloxifene, a selective estrogen receptor modulator, improves cognitive function compared with placebo in women with Alzheimer disease (AD) and to provide an estimate of cognitive effect.

METHODS

This pilot study was conducted as a randomized, double-blind, placebo-controlled trial, with a planned treatment of 12 months. Women with late-onset AD of mild to moderate severity were randomly allocated to high-dose (120 mg) oral raloxifene or identical placebo provided once daily. The primary outcome compared between treatment groups at 12 months was change in the Alzheimer's Disease Assessment Scale, cognitive subscale (ADAS-cog).

RESULTS

Forty-two women randomized to raloxifene or placebo were included in intent-to-treat analyses (mean age 76 years, range 68-84), and 39 women contributed 12-month outcomes. ADAS-cog change scores at 12 months did not differ significantly between treatment groups (standardized difference 0.03, 95% confidence interval -0.39 to 0.44, 2-tailed p = 0.89). Raloxifene and placebo groups did not differ significantly on secondary analyses of dementia rating, activities of daily living, behavior, or a global cognition composite score. Caregiver burden and caregiver distress were similar in both groups.

CONCLUSIONS

Results on the primary outcome showed no cognitive benefits in the raloxifene-treated group.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that for women with AD, raloxifene does not have a significant cognitive effect. The study lacked the precision to exclude a small effect.

Redox biology in normal cells and cancer: restoring function of the redox/Fyn/c-Cbl pathway in cancer cells offers new approaches to cancer treatment

This review discusses a unique discovery path starting with novel findings on redox regulation of precursor cell and signaling pathway function and identification of a new mechanism by which relatively small changes in redox status can control entire signaling networks that regulate self-renewal, differentiation, and survival. The pathway central to this work, the redox/Fyn/c-Cbl (RFC) pathway, converts small increases in oxidative status to pan-activation of the c-Cbl ubiquitin ligase, which controls multiple receptors and other proteins of central importance in precursor cell and cancer cell function. Integration of work on the RFC pathway with attempts to understand how treatment with systemic chemotherapy causes neurological problems led to the discovery that glioblastomas (GBMs) and basal-like breast cancers (BLBCs) inhibit c-Cbl function through altered utilization of the cytoskeletal regulators Cool-1/βpix and Cdc42, respectively. Inhibition of these proteins to restore normal c-Cbl function suppresses cancer cell division, increases sensitivity to chemotherapy, disrupts tumor-initiating cell (TIC) activity in GBMs and BLBCs, controls multiple critical TIC regulators, and also allows targeting of non-TICs. Moreover, these manipulations do not increase chemosensitivity or suppress division of nontransformed cells. Restoration of normal c-Cbl function also allows more effective harnessing of estrogen receptor-α (ERα)-independent activities of tamoxifen to activate the RFC pathway and target ERα-negative cancer cells. Our work thus provides a discovery strategy that reveals mechanisms and therapeutic targets that cannot be deduced by standard genetics analyses, which fail to reveal the metabolic information, isoform shifts, protein activation, protein complexes, and protein degradation critical to our discoveries.

A bluish-green emitting organic compound methyl 3-[(E)-(2-hydroxy-1-naphthyl)methylidene]carbazate: spectroscopic, thermal, fluorescence, antimicrobial and molecular docking studies

The present paper describes the physicochemical properties and biological activities of a Schiff base compound which was grown by the slow evaporation solution growth technique.

Oestrogen, ocular function and low-level vision: a review

Over the past 10 years, a literature has emerged concerning the sex steroid hormone oestrogen and its role in human vision. Herein, we review evidence that oestrogen (oestradiol) levels may significantly affect ocular function and low-level vision, particularly in older females. In doing so, we have examined a number of vision-related disorders including dry eye, cataract, increased intraocular pressure, glaucoma, age-related macular degeneration and Leber's hereditary optic neuropathy. In each case, we have found oestrogen, or lack thereof, to have a role. We have also included discussion of how oestrogen-related pharmacological treatments for menopause and breast cancer can impact the pathology of the eye and a number of psychophysical aspects of vision. Finally, we have reviewed oestrogen's pharmacology and suggest potential mechanisms underlying its beneficial effects, with particular emphasis on anti-apoptotic and vascular effects.

Use of SERMs for treatment in postmenopausal women

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'.

MEK1/2 inhibition suppresses tamoxifen toxicity on CNS glial progenitor cells

It is increasingly apparent that treatment with a variety of anticancer agents often is associated with adverse neurological consequences. Clinical studies indicate that exposure even to tamoxifen (TMX), a putatively benign antihormonal agent widely used in breast cancer treatment, causes cognitive dysfunction and changes in CNS metabolism, hippocampal volume, and brain structure. We found that TMX is toxic for a variety of CNS cell populations in vitro and also increased cell death in the corpus callosum and reduced cell division in the mouse subventricular zone, the hippocampal dentate gyrus, and the corpus callosum. We further discovered that MEK1/2 inhibition selectively rescued primary glial progenitors from TMX toxicity in vitro while enhancing TMX effects on MCF7 luminal human breast cancer cells. In vivo, MEK1/2 inhibition prevented TMX-induced cell death in systemically treated mice. Our results demonstrate unexpected cytotoxicity of this putatively benign antihormonal agent and offer a potential strategy for rescuing CNS cells from adverse effects of TMX.

Cognitive factors associated with adherence to oral antiestrogen therapy: results from the cognition in the study of tamoxifen and raloxifene (Co-STAR) study

Little is known about the cognitive factors associated with adherence to antiestrogen therapy. Our objective was to investigate the association between domain-specific cognitive function and adherence among women in a clinical prevention trial of oral antiestrogen therapies. We performed a secondary analysis of Co-STAR, an ancillary study of the STAR breast cancer prevention trial in which postmenopausal women at increased breast cancer risk were randomized to tamoxifen or raloxifene. Co-STAR enrolled nondemented participants ≥65 years old to compare treatment effects on cognition. The cognitive battery assessed global cognitive function (Modified Mini-Mental State Exam), and specific cognitive domains of verbal knowledge, verbal fluency, figural memory, verbal memory, attention and working memory, spatial ability, and fine motor speed. Adherence was defined by a ratio of actual time taking therapy per protocol ≥80% of expected time. Logistic regression was used to evaluate the association between cognitive test scores and adherence to therapy. The mean age of the 1,331 Co-STAR participants was 67.2 ± 4.3 years. Mean 3MS score was 95.1 (4.7) and 14% were nonadherent. In adjusted analyses, the odds of nonadherence were lower for those with better scores on verbal memory [OR (95% confidence interval): 0.75 (0.62-0.92)]. Larger relative deficits in verbal memory compared with verbal fluency were also associated with nonadherence [1.28 (1.08-1.51)]. Among nondemented older women, subtle differences in memory performance were associated with medication adherence. Differential performance across cognitive domains may help identify persons at greater risk for poor adherence.

Is basic research providing answers if adjuvant anti-estrogen treatment of breast cancer can induce cognitive impairment?

Adjuvant treatment of cancer by chemotherapy is associated with cognitive impairment in some cancer survivors. Breast cancer patients are frequently also receiving endocrine therapy with selective estrogen receptor modulators (SERMs) and/or aromatase inhibitors (AIs) to suppress the growth of estradiol sensitive breast tumors. Estrogens are well-known, however, to target brain areas involved in the regulation of cognitive behavior. In this review clinical and basic preclinical research is reviewed on the actions of estradiol, SERMs and AIs on brain and cognitive functioning to see if endocrine therapy potentially induces cognitive impairment and in that respect may contribute to the detrimental effects of chemotherapy on cognitive performance in breast cancer patients. Although many clinical studies may be underpowered to detect changes in cognitive function, current basic and clinical reports suggest that there is little evidence that AIs may have a lasting detrimental effect on cognitive performance in breast cancer patients. The clinical data on SERMs are not conclusive, but some studies do suggest that tamoxifen administration may form a risk for cognitive functioning particularly in older women. An explanation may come from basic preclinical research which indicates that tamoxifen often acts agonistic in the absence of estradiol but antagonistic in the presence of endogenous estradiol. It could be hypothesized that the negative effects of tamoxifen in older women is related to the so-called window of opportunity for estrogen. Administration of SERMs beyond this so-called window of opportunity may not be effective or might even have detrimental effects similar to estradiol.

Hormone therapy, dementia, and cognition: the Women's Health Initiative 10 years on

Principal findings on dementia from the Women's Health Initiative Memory Study (WHIMS) showed that conjugated equine estrogens plus medroxyprogesterone acetate (CEE/MPA) increase dementia risk in women aged 65 years and above, but not risk of mild cognitive impairment. The dementia finding was unexpected, given consistent observational evidence that associates use of estrogen-containing hormone therapy with reduced risk of Alzheimer's disease. It remains controversial whether hormone use by younger postmenopausal women near the time of menopause reduces dementia risk or whether WHIMS findings should be generalized to younger women. Given the challenges of conducting a primary prevention trial to address that question, it is helpful to consider the impact of hormone therapy on cognitive test performance, particularly verbal memory, for its own sake and as a proxy for dementia risk. The WHI Study of Cognitive Aging (WHISCA) showed that CEE/MPA worsened verbal memory, whereas CEE alone had no influence on cognition. These findings have been replicated in several randomized, clinical trials. The apparent negative effect of CEE/MPA on verbal memory does not appear to be age-dependent. Additional investigations are needed to understand the impact of other hormonally active compounds on dementia and cognitive outcomes.

Neuroprotective actions of estradiol revisited

Results from animal experiments showing that estradiol is neuroprotective were challenged 10 years ago by findings indicating an increased risk of dementia and stroke in women over 65 years of age taking conjugated equine estrogens. Our understanding of the complex signaling of estradiol in neural cells has recently clarified the causes of this discrepancy. New data indicate that estradiol may lose its neuroprotective activity or even increase neural damage, a situation that depends on the duration of ovarian hormone deprivation and on age-associated modifications in the levels of other molecules that modulate estradiol action. These studies highlight the complex neuroprotective mechanisms of estradiol and suggest a window of opportunity during which effective hormonal therapy could promote brain function and cognition.

Hormonal influences on cognition and risk for Alzheimer's disease

Research increasingly suggests that changes in estrogen levels during aging may increase the risk of Alzheimer's disease, the most common type of dementia. This update reviews the newest information about estrogen and cognitive aging, including information regarding the role of bioavailable estrogen in older women and men, use of selective estrogen receptor modulators to improve cognition, and studies of genetic risk factors to elucidate the effects of endogenous estrogen on aging and cognition. Future trials are needed to determine whether alternate timing, dosage, formulation, or method of administration of hormone replacement can reduce the risk of dementia.

Cognitive changes associated with endocrine therapy for breast cancer

Endocrine therapy in the setting of breast cancer has undoubtedly advanced clinical outcomes in this disease, but treatment with endocrine therapy is accompanied by a wide spectrum of side effects. It is of prime importance to understand and characterize these toxicities to facilitate clinical decision-making. Somewhat surprisingly, there is a relative paucity of data pertaining to cognitive changes associated with endocrine therapy. In this article we review cognitive associated with two classes of endocrine therapy: (1) selective estrogen receptor modulators (SERMs; tamoxifen and raloxifene) and (2) aromatase inhibitors (AIs; anastrozole, letrozole, and exemestane). Companion studies to the Multiple Outcome of Raloxifene Evaluation (MORE), the Study of Tamoxifen and Raloxifene (STAR) and National Surgical Adjuvant Breast and Bowel Project (NSABP) P-1 trials provide relevant data to understand the effect of SERMs on cognition. In contrast, substudies of the Arimidex, Tamoxifen Alone or in Combination (ATAC), Tamoxifen and Exemestane Adjuvant Multinational (TEAM) and Breast International Group (BIG) 1-98 trials juxtapose cognitive effects of AIs against those of tamoxifen. These and other studies are examined herein to provide a comprehensive overview of the effect of endocrine therapy on cognition.