Endoxifen, an Estrogen Receptor Targeted Therapy: From Bench to Bedside

The selective estrogen receptor (ER) modulator, tamoxifen, is the only endocrine agent with approvals for both the prevention and treatment of premenopausal and postmenopausal estrogen-receptor positive breast cancer as well as for the treatment of male breast cancer. Endoxifen, a secondary metabolite resulting from CYP2D6-dependent biotransformation of the primary tamoxifen metabolite, N-desmethyltamoxifen (NDT), is a more potent antiestrogen than either NDT or the parent drug, tamoxifen. However, endoxifen's antitumor effects may be related to additional molecular mechanisms of action, apart from its effects on ER. In phase 1/2 clinical studies, the efficacy of Z-endoxifen, the active isomer of endoxifen, was evaluated in patients with endocrine-refractory metastatic breast cancer as well as in patients with gynecologic, desmoid, and hormone-receptor positive solid tumors, and demonstrated substantial oral bioavailability and promising antitumor activity. Apart from its potent anticancer effects, Z-endoxifen appears to result in similar or even greater bone agonistic effects while resulting in little or no endometrial proliferative effects compared with tamoxifen. In this review, we summarize the preclinical and clinical studies evaluating endoxifen in the context of breast and other solid tumors, the potential benefits of endoxifen in bone, as well as its emerging role as an antimanic agent in bipolar disorder. In total, the summarized body of literature provides compelling arguments for the ongoing development of Z-endoxifen as a novel drug for multiple indications.

Update on Osteoporosis Screening and Management

Osteoporosis is a metabolic bone disease characterized by low bone mass and microarchitectural deterioration of bone tissue leading to an increased risk of fragility fractures. Central dual-energy X-ray absorptiometry measurements are the gold standard for determining bone mineral density. A well-balanced diet containing adequate amounts of calcium and vitamin D, exercise, smoking cessation, and limited alcohol intake are important to maintain bone health. Pharmacologic agents should be recommended in postmenopausal women who are at high risk for fractures. Newer anabolic therapies including teriparatide, abaloparatide, and romosozumab have emerged for use in severe osteoporosis.

Turning scientific serendipity into discoveries in breast cancer research and treatment: a tale of PhD students and a 50-year roaming tamoxifen team

PURPOSE

This retrospective, about a single "mobile" laboratory in six locations on two continents, is intended as a case study in discovery for trainees and junior faculty in the medical sciences. Your knowledge of your topic is necessary to expect the unexpected.

HISTORICAL METHOD

In 1972, there was no tamoxifen, only ICI 46, 474, a non-steroidal anti-estrogen with little chance of clinical development. No one would ever be foolish enough to predict that the medicine, 20 years later, would achieve legendary status as the first targeted treatment for breast cancer, and millions of women would benefit from long-term adjuvant tamoxifen therapy. The secret of tamoxifen's success was a translational research strategy proposed in the mid 1970's. This strategy was to treat only patients with estrogen receptor (ER)-positive breast cancer and deploy 5 or more years of adjuvant tamoxifen therapy to prevent recurrence. Additionally, tamoxifen prevented mammary cancer in animals. Could the medicine prevent breast cancer in women?

RESULTS

Tamoxifen and the failed breast cancer drug raloxifene became the first selective estrogen receptor modulators (SERMs): a new drug group, discovered at the University of Wisconsin, Comprehensive Cancer Center. Serendipity can play a fundamental role in discovery, but there must be a rigorous preparation for the investigator to appreciate the possibility of a pending discovery. This article follows the unanticipated discoveries when PhD students "get the wrong answer." The secret of success of my six Tamoxifen Teams was their technical excellence to create models, to decipher mechanisms, that drove the development of new medicines. Discoveries are listed that either changed women's health or allowed an understanding of originally opaque mechanisms of action of potential therapies. These advances in women's health were supported entirely by government-sponsored peer-reviewed funding and major philanthropy from the Lynn Sage Breast Cancer Foundation, the Avon Foundation, and the Susan G. Komen Breast Cancer Foundation. The resulting lives saved or extended, families aided in a time of crisis and the injection of billions of dollars into national economies by drug development, is proof of the value of Federal or philanthropic investment into unencumbered research aimed at saving millions of lives.

Bazedoxifene, a Selective Estrogen Receptor Modulator, Promotes Functional Recovery in a Spinal Cord Injury Rat Model

In research on various central nervous system injuries, bazedoxifene acetate (BZA) has shown two main effects: neuroprotection by suppressing the inflammatory response and remyelination by enhancing oligodendrocyte precursor cell differentiation and oligodendrocyte proliferation. We examined the effects of BZA in a rat spinal cord injury (SCI) model. Anti-inflammatory and anti-apoptotic effects were investigated in RAW 264.7 cells, and blood-spinal cord barrier (BSCB) permeability and angiogenesis were evaluated in a human brain endothelial cell line (hCMEC/D3). In vivo experiments were carried out on female Sprague Dawley rats subjected to moderate static compression SCI. The rats were intraperitoneally injected with either vehicle or BZA (1mg/kg pre-SCI and 3 mg/kg for 7 days post-SCI) daily. BZA decreased the lipopolysaccharide-induced production of proinflammatory cytokines and nitric oxide in RAW 264.7 cells and preserved BSCB disruption in hCMEC/D3 cells. In the rats, BZA reduced caspase-3 activity at 1 day post-injury (dpi) and suppressed phosphorylation of MAPK (p38 and ERK) at dpi 2, hence reducing the expression of IL-6, a proinflammatory cytokine. BZA also led to remyelination at dpi 20. BZA contributed to improvements in locomotor recovery after compressive SCI. This evidence suggests that BZA may have therapeutic potential to promote neuroprotection, remyelination, and functional outcomes following SCI.

Successful treatment of a case of hormone receptor-positive metastatic extramammary Paget disease with tamoxifen

Extramammary Paget disease (EMPD) is a rare cutaneous adenocarcinoma that usually is of epidermal origin and shows glandular differentiation and that is treated by wide local excision depending on the disease extent. For widely metastatic disease, however, a standard treatment remains to be established. Similar to breast cancer, EMPD has been found to overexpress human epidermal growth factor receptor 2 (HER2) or hormone receptors (HRs). Whereas HER2-directed therapy was recently shown to be effective for HER2-positive EMPD, the potential role of endocrine therapy for HR-positive EMPD has remained unknown. We here report a case of metastatic EMPD with HR positivity that was successfully treated with the selective estrogen receptor modulator tamoxifen. This first-line treatment of systemic metastasis resulted in durable tumor regression for > 20 months without any treatment-related toxicities. This is the first report to reveal the promise of tamoxifen as a safe and effective treatment for HR-positive metastatic EMPD.

ESR1 mutation as an emerging clinical biomarker in metastatic hormone receptor-positive breast cancer

In metastatic hormone receptor-positive breast cancer, ESR1 mutations are a common cause of acquired resistance to the backbone of therapy, estrogen deprivation by aromatase inhibition. How these mutations affect tumor sensitivity to established and novel therapies are active areas of research. These therapies include estrogen receptor-targeting agents, such as selective estrogen receptor modulators, covalent antagonists, and degraders (including tamoxifen, fulvestrant, and novel agents), and combination therapies, such as endocrine therapy plus CDK4/6, PI3K, or mTORC1 inhibition. In this review, we summarize existing knowledge surrounding the mechanisms of action of ESR1 mutations and roles in resistance to aromatase inhibition. We then analyze the recent literature on how ESR1 mutations affect outcomes in estrogen receptor-targeting and combination therapies. For estrogen receptor-targeting therapies such as tamoxifen and fulvestrant, ESR1 mutations cause relative resistance in vitro but do not clearly lead to resistance in patients, making novel agents in this category promising. Regarding combination therapies, ESR1 mutations nullify any aromatase inhibitor component of the combination. Thus, combinations using endocrine alternatives to aromatase inhibition, or combinations where the non-endocrine component is efficacious as monotherapy, are still effective against ESR1 mutations. These results emphasize the importance of investigating combinatorial resistance, challenging as these efforts are. We also discuss future directions and open questions, such as studying the differences among distinct ESR1 mutations, asking how to adjust clinical decisions based on molecular surveillance testing, and developing novel therapies that are effective against ESR1 mutations.

Add-On Selective Estrogen Receptor Modulators for Methadone Maintenance Treatment

Methadone maintenance treatment (MMT) remains the cornerstone for the management of opiate abuse. However, MMT can be associated with complex factors, including complications during the tolerance phase, the inability of some patients to maintain treatment effects during the tapering or abstinence phases, and the development of methadone dependence. Previous studies have revealed a sex disparity in MMT efficacy, showing that women undergoing MMT experiencing an increase in psychological symptoms compared with men and suggesting a link between disparate responses and the effects of estrogen signaling on methadone metabolism. More specifically, estradiol levels are positively associated with MMT dosing, and the expression of a single-nucleotide polymorphism (SNP) associated with estrogen receptor (ER) regulation is also associated with MMT dosing. In addition to performing mechanistic dissections of estrogen signaling in the presence of methadone, past studies have also proposed the targeting of estrogen signaling during MMT. The present report provides an overview of the relevant literature regarding sex effects, including differences in sex hormones and their potential impacts on MMT regimens. Moreover, this article provides a pharmacological perspective on the targeting of estrogen signals through the use of selective ER modulators (SERMs) during MMT. Preliminary preclinical experiments were also performed to evaluate the potential effects of targeting estrogen signaling with tamoxifen on methadone metabolism.

Oral Selective Estrogen Receptor Degraders (SERDs) as a Novel Breast Cancer Therapy: Present and Future from a Clinical Perspective

Estrogen receptor-positive (ER+) is the most common subtype of breast cancer. Endocrine therapy is the fundamental treatment against this entity, by directly or indirectly modifying estrogen production. Recent advances in novel compounds, such as cyclin-dependent kinase 4/6 inhibitors (CDK4/6i), or phosphoinositide 3-kinase (PI3K) inhibitors have improved progression-free survival and overall survival in these patients. However, some patients still develop endocrine resistance after or during endocrine treatment. Different underlying mechanisms have been identified as responsible for endocrine treatment resistance, where ESR1 gene mutations are one of the most studied, outstanding from others such as somatic alterations, microenvironment involvement and epigenetic changes. In this scenario, selective estrogen receptor degraders/downregulators (SERD) are one of the weapons currently in research and development against aromatase inhibitor- or tamoxifen-resistance. The first SERD to be developed and approved for ER+ breast cancer was fulvestrant, demonstrating also interesting activity in ESR1 mutated patients in the second line treatment setting. Recent investigational advances have allowed the development of new oral bioavailable SERDs. This review describes the evolution and ongoing studies in SERDs and new molecules against ER, with the hope that these novel drugs may improve our patients’ future landscape.

Water extract of Er-xian decoction selectively exerts estrogenic activities and interacts with SERMs in estrogen-sensitive tissues

ETHNOPHARMACOLOGICAL RELEVANCE

The increasing use of "kidney"-nourishing Traditional Chinese Medicine (TCM) like Er-xian decoction (EXD) for management of menopausal symptoms and osteoporosis has aroused concerns about their safety, and whether they interact with prescription drugs as both of them act via estrogen receptors (ERs) and regulate serum estradiol.

AIM OF THE STUDY

The present study aimed to evaluate whether EXD selectively exerted estrogenic activities and interacted with Selective Estrogen Receptor Modulators (SERMs).

MATERIALS AND METHODS

In vivo, mature ovariectomized (OVX) rats were administrated with EXD or combined treatment of EXD and SERMs for 12 weeks. The tissue-selective effect of EXD and its interaction of SERMs were studied in four estrogen sensitive tissues, bone, brain, breast and uterus. In vitro, the interaction of extracts of EXD-treated serum and SERMs in four ER-positive cell lines.

RESULTS

In OVX rats, EXD selectively alleviated estrogen deficiency-induced changes in the bone and brain without inducing any estrogenic effects in the breast or uterus. Two-way ANOVA indicated the presence of interactions between EXD and SERMs in OVX rats but EXD did not significantly alter the tissue responses to SERMs in the bone, breast or brain. Indeed, the combined use of EXD and SERMs appeared to suppress the estrogenic effect of raloxifene and tamoxifen in the uterus. Extract of EXD-treated serum directly stimulated cell proliferation or differentiation in human osteosarcoma MG-63, neuroblastoma SHSY5Y, breast cancer MCF-7, and endometrial Ishikawa cells. Two-way ANOVA revealed that EXD-treated serum interacted with SERMs at various concentrations and altered the effects of tamoxifen in MG-63 and MCF-7 cells.

CONCLUSIONS

EXD exerted estrogenic effects in a tissue-selective manner and interacted with SERMs. Combined treatment of EXD and SERMs did not hamper the beneficial effects of SERMs on the bone or brain but appeared to moderate the estrogenic effect of SERMs in the uterus.

Incidence and Risk of Venous Thromboembolism in Bisphosphonates and Selective Estrogen Receptor Modulators Treatment in Korea

BACKGROUND

Selective estrogen receptor modulators (SERMs) were associated with an increased risk of venous thromboembolism (VTE) due to the estrogen effect. In this study, we investigated the effect of SERMs on VTE compared to bisphosphonates (BPs) using the Korean National Health Insurance claims database.

METHODS

This was a retrospective cohort study. Women over 50 years old who were first prescribed BPs or SERMs for osteoporosis treatment in 2012 were included. The difference in VTE incidence between the SERMs and BP groups was compared. Both groups were followed up for VTE or PE occurrence, death, or until December 2016. The study population was analyzed by 3:1 matching according to age using a multivariate Cox model.

RESULTS

The hazard ratio (HR) for VTE was 0.72 (95% confidence interval [CI], 0.40-1.28) in the SERMs group compared to BP group. Older age (60-69 vs. 50-59 years: HR, 3.77; 95% CI, 2.07-6.86 and 70-79 vs. 50-59 years: HR, 5.88; 95% CI, 3.14-11.02), major osteoporotic fracture (HR, 1.77; 95% CI, 1.16- 2.70), atrial fibrillation (HR, 3.31; 95% CI, 1.35-8.11), and estrogen replacement (HR, 3.40; 95% CI, 2.01-5.73) all increased VTE risk. In subgroup analysis of the SERMs group, past hospitalization (HR, 2.24; 95% CI, 1.02-4.92), estrogen replacement (HR, 5.75; 95% CI, 2.29-14.39), and glucocorticoid replacement (HR, 2.71; 95% CI, 1.05-7.0) increased VTE risk.

CONCLUSION

SERMs did not increase the risk of VTE compared to BPs in Koreans with osteoporosis. However, old age and estrogen replacement both increased VTE risk.

Endocrine prevention of breast cancer

Breast cancer (BC) is the most common non-cutaneous malignancy among women worldwide and is a significant cause of morbidity, mortality, and national health care expenditure. Unfortunately, with few exceptions like alcohol consumption, obesity, and physical activity, most BC risk factors are unmodifiable. Antiestrogen endocrine therapy, commonly known as BC chemoprevention, is an effective method of BC prevention. In multiple randomized trials, two selective estrogen receptor modulators - tamoxifen and raloxifene, and two aromatase inhibitors - exemestane and anastrozole have reduced BC incidence by 50%-65% in high-risk women. An estimated 15% of the US women between 35 and 79 years of age may qualify as high risk for BC, yet a small percentage of these women will ever have a formal BC risk assessment or a discussion of endocrine prevention options. The etiology of underutilization of endocrine prevention of BC is multifactorial - infrequent use of BC risk assessment tools in the primary care settings, insufficient knowledge of BC risk assessment tools and antiestrogen agents among primary care providers, concerns of side effects, inadequate time for counseling during primary care visit, and lack of predictive biomarkers may play significant roles. Many small studies incorporating risk assessment tools and decision-making aids showed minimal success in enhancing endocrine prevention. One critical factor for underutilization of endocrine prevention is low uptake of endocrine prevention by high-risk women even when appropriately recommended. Furthermore, adherence to BC endocrine prevention is unsatisfactorily low. Despite the current infrequent usage, endocrine prevention has the potential to reduce the public health burden of BC significantly. Innovative approaches like finding new agents, alternative dosing and schedule of currently available agents, transdermal medication delivery, increased public and professional awareness, and policymakers' commitments may bring the desired changes.

Raloxifene retards the progression of adjacent segmental intervertebral disc degeneration by inhibiting apoptosis of nucleus pulposus in ovariectomized rats

BACKGROUND

Adjacent segmental intervertebral disk degeneration (ASDD) is a major complication secondary to lumbar fusion. Although ASSD pathogenesis remains unclear, the primary cause of intervertebral disk degeneration (IVDD) development is apoptosis of nucleus pulposus (NP). Raloxifene (RAL) could delay ASDD by inhibiting NP apoptosis.

METHODS

An ASDD rat model was established by ovariectomy (OVX) and posterolateral spinal fusion (PLF) on levels 4-5 of the lumbar vertebrae. Rats in the treatment groups were administered 1 mg/kg/d RAL by gavage for 12 weeks, following which, all animals were euthanized. Lumbar fusion, apoptosis, ASDD, and vertebrae micro-architecture were evaluated.

RESULTS

RAL maintained intervertebral disk height (DHI), delayed vertebral osteoporosis, reduced histological score, and inhibited apoptosis. The OVX+PLF+RAL group revealed upregulated expression of aggrecan and B-cell lymphoma-2 (bcl2), as well as significantly downregulated expression of a disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS-4), metalloproteinase-13 (MMP-13), caspase-3, BCL2-associated X (bax), and transferase dUTP nick end labeling (TUNEL) staining. Micro-computed tomography (Micro-CT) analysis revealed higher bone volume fraction (BV/TV), bone mineral density (BMD), and trabecular number (Tb.N), and lower trabecular separation (Tb.Sp) in OVX+PLF+RAL group than in the OVX+PLF group.

CONCLUSIONS

RAL can postpone ASDD development in OVX rats through inhibiting extracellular matrix metabolic imbalance, NP cell apoptosis, and vertebral osteoporosis. These findings showed RAL as a potential therapeutic target for ASDD.

Selective oestrogen receptor modulators (SERMs) for endometriosis

BACKGROUND

Endometriosis is defined as the presence of endometrial tissue outside the uterine cavity. This chronic and recurring condition occurs in women of reproductive age. It is a common cause of pain or infertility and can cause non-specific symptoms such as lower back pain, dyspareunia (pain during or after intercourse), and dysmenorrhoea (menstrual pain). Endometriosis is an oestrogen-dependent disease. Medical treatment aims to relieve symptoms and shrink lesions by suppressing the normal menstrual cycle. In this review, we consider medication specifically aiming to modulate oestrogen receptors as an alternative method of treatment.

OBJECTIVES

To evaluate the effectiveness and safety of selective oestrogen receptor modulators (SERMs) in the management of endometriosis.

SEARCH METHODS

We searched for trials in the following databases (from their inception to 28 May 2020): Cochrane Gynaecology and Fertility Group Specialised Register, Cochrane Central Register of Studies (CRS Online), MEDLINE, Embase, CINAHL, PsycINFO, and registers of ongoing trials. In addition, we searched all reference lists of included trials, and we contacted experts in the field, in an attempt to locate trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing selective oestrogen receptor modulators (SERMs) with placebo, no treatment, other medical treatment, or surgery for endometriosis.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. Two review authors independently selected trials for inclusion, assessed risk of bias, and extracted data using data extraction forms. We used risk ratios (RRs) with 95% confidence intervals (CIs) for reporting dichotomous data. Primary review outcomes were relief of pelvic pain and adverse events. Secondary outcomes included quality of life, recurrence rate, and economic and fertility outcomes.

MAIN RESULTS

We included only one RCT, which included 93 women, comparing the SERM raloxifene with placebo in biopsy-proven endometriosis. All women first underwent complete surgical excision of all lesions. Evidence was of very low quality: the main limitation was imprecision - with very sparse data from only one small study, which included only women after surgical treatment. Relief of pelvic pain The included study did not specifically measure the primary outcome of pain relief. Study authors reported that time to return of pelvic pain (defined as two months of pain equal to or more severe than pain at study entry) was more rapid in the raloxifene group (P = 0.03). Adverse events The included study reported adverse events such as pelvic pain, ovarian cyst, headache, migraine, and depression. We are uncertain whether raloxifene improves the incidence of pelvic pain (RR 1.25, 95% CI 0.63 to 2.45), ovarian cysts (RR 1.57, 95% CI 0.55 to 4.43), headache (RR 1.09, 95% CI 0.49 to 2.43), migraine (RR 0.73, 95% CI 0.28 to 1.95), depression (RR 1.96, 95% CI 0.63 to 6.06), or other adverse events (RR 0.08, 95% CI 0.00 to 1.30) (all: 1 study, n = 93; very low-quality evidence). Quality of life The study described a statistically significant difference in mental health quality of life (QoL) by 12 months, in favour of placebo treatment (mean difference 11.1, 95% CI 0.01 to 21.19). Other QoL data did not differ between groups but were not reported in detail. Recurrence rate, fertility, and economic outcomes We are uncertain whether raloxifene improves the recurrence rate of endometriosis, proven by biopsy, when compared to placebo (RR 1.20, 95% CI 0.66 to 2.21; 1 study, n = 93; very low-quality evidence). This suggests that if 28% of women taking placebo have biopsy-proven recurrence of endometriosis, between 19% and 62% of those taking raloxifene will do so. These outcomes are prone to bias, as not all women had an actual second laparoscopy. Recurrence based on symptoms (non-menstrual pain, dysmenorrhoea, or dyspareunia) was described; in these cases, symptoms improved after use of raloxifene as well as after use of placebo. The included study did not report data on economic outcomes. No comparative data were available on pregnancy, as the study included only women who agreed to postpone pregnancy until after the study endpoint; the few pregnancies that did occur were uneventful but were regarded as an adverse event.  AUTHORS' CONCLUSIONS: Based on a single, small RCT and incomplete data, we are uncertain of the effects of SERMs on pain relief in surgically treated patients with endometriosis. The included study was stopped prematurely because of higher pain scores among women who took SERMs when compared to scores among those receiving placebo. Further research is needed to fully evaluate the role of SERMs in endometriosis.

Raloxifene is a Female-specific Proteostasis Therapeutic in the Spinal Cord

Several neurodegenerative disorders are characterized by proteasome dysfunctions leading to protein aggregations and pathogenesis. Since we showed that estrogen receptor alpha (ERα) activates the proteasome, drugs able to stimulate ERα in the central nervous system (CNS) could hold potential for therapeutic intervention. However, the transcriptional effects of selective estrogen receptor modulators (SERMs), such as tamoxifen and raloxifene, can be tissue specific. A direct comparison of the effects of different SERMs on gene transcription in the CNS has never been performed. Here, we report an RNA-seq analysis of the spinal cord treated with estrogen, tamoxifen, or raloxifene. We find stark SERM and sex-specific differences in gene expression profiles in the spinal cord. Notably, raloxifene, but not estrogen or tamoxifen, modulates numerous deubiquitinating enzymes, proteasome subunits and assembly factors, and these effects translate into decreased protein aggregates. In the SOD1-G93A mouse model of amyotrophic lateral sclerosis, we found that even a low dose of raloxifene causes a significant decrease in mutant SOD1 aggregates in the spinal cord, accompanied by a delay in the decline of muscle strength in females, but not in males. These results strongly indicate SERM-selective as well as sex-specific effects, and emphasize the importance of sex as a biological variable to be considered for the careful selection of specific SERM for use in clinical trials for neurodegenerative diseases.

Meta-analyses of phase 3 randomised controlled trials of third generation aromatase inhibitors versus tamoxifen as first-line endocrine therapy in postmenopausal women with hormone receptor-positive advanced breast cancer

BACKGROUND

Four randomised controlled trials (RCTs) in postmenopausal women with advanced breast cancer (ABC) comparing aromatase inhibitors (AIs) versus the selective estrogen receptor modulator tamoxifen, each individually reported significantly longer progression-free survival (PFS) but none showed a significant difference in overall survival (OS). In these trials between 6.8% and 55% of tumours were hormone receptor (HR) status unknown or negative. This meta-analysis restricted the comparison to HR-positive (HR+) tumours.

METHODS

Anonymised individual patient data were obtained from three RCTs, EORTC (exemestane versus tamoxifen), Study 0027 and Study 0030 (both anastrozole versus tamoxifen). For the remaining RCT (Femara Study PO25; letrozole versus tamoxifen), odds ratio (OR) or hazard ratio (HzR), with confidence intervals were obtained from the clinical study report, for patients with HR+ tumours, in addition to published data. In total, data were obtained from 2296 patients; 1560 (68%) had HR+ ABC.

FINDINGS

The OR for clinical benefit rate was 1.56, in favour of AIs (p < 0.001). The duration of clinical benefit was not significantly increased by AIs (HzR 0·88; p = 0.08). For PFS the HzR (0.82) was in favour of AIs (p = 0·007). However, for OS the HzR (1.05) was not significantly different between AIs and tamoxifen (p = 0.42).

INTERPRETATION

Although third generation AIs put significantly more patients into 'clinical benefit', their tumours were not controlled for significantly longer. Overall, while this resulted in a significantly greater PFS in favour of the AIs, this did not translate into improvement in OS.

Selective Estrogen Receptor Modulators: A Potential Option For Non-Binary Gender-Affirming Hormonal Care?

Gender dysphoria describes the distress associated with having a gender identity that differs from one's birth-assigned sex. To relieve this distress, transgender, and gender diverse (henceforth, trans) individuals commonly undergo medical transition involving hormonal treatments. Current hormonal treatment guidelines cater almost exclusively for those who wish to transition from male to female or vice versa. In contrast, there is a dearth of hormonal options for those trans individuals who identify as non-binary and seek an androgynous appearance that is neither overtly male nor female. Though prolonged puberty suppression with gonadotrophin releasing hormone agonists (GnRHa) could in theory be gender-affirming by preventing the development of unwanted secondary sex characteristics, this treatment option would be limited to pre- or peri-pubertal adolescents and likely have harmful effects. Here, we discuss the theoretical use of Selective Estrogen Receptor Modulators (SERMs) for non-binary people assigned male at birth (AMAB) who are seeking an androgynous appearance through partial feminization without breast growth. Given their unique range of pharmacodynamic effects, SERMs may represent a potential gender-affirming treatment for this population, but there is a lack of knowledge regarding their use and potentially adverse effects in this context.

Treatment of Men with Central Hypogonadism: Alternatives for Testosterone Replacement Therapy

Central hypogonadism is a clinical condition, characterized by sexual symptoms and low serum testosterone levels, due to an impaired function of the hypothalamus or pituitary gland. Testosterone replacement therapy (TRT) is the standard treatment for hypogonadism, but it has some disadvantages. TRT is not a good option in men wishing to preserve fertility, nor in men with (a high risk of) prostate cancer, polycythemia, thrombophilia and severe cardiovascular disease. In this review, we discuss alternative treatments for central hypogonadism. If reversible causes are present, non-pharmacological interventions can be therapeutic. Gonadotropins are a good alternative to TRT when fertility is desired in the near future though they require frequent injections. Clomiphene citrate and tamoxifen seem to be a safe alternative for the treatment of functional central hypogonadism in men, as several studies reported a significant increase in testosterone levels with these drugs. However, their use is off-label and data supporting the efficacy of clomiphene citrate and tamoxifen on hypogonadal symptoms are insufficient. For this reason, clomiphene citrate and tamoxifen should not be used in routine clinical practice to treat sexual symptoms in men with central hypogonadism.

A cost-effectiveness analysis of vaginal carbon dioxide laser therapy compared with standard medical therapies for genitourinary syndrome of menopause-associated dyspareunia

BACKGROUND

Topical vaginal estrogen therapy is considered the gold standard treatment for genitourinary syndrome of menopause-associated dyspareunia, but early investigations of energy-based devices show promise for patients with contraindications or those who are refractory to vaginal estrogen cream therapy. Although evaluating safety, efficacy, and long-term outcomes for novel technologies is critically important when new technologies become available to treat unmet healthcare needs, evaluation of the costs of these new technologies compared with existing therapies is also critically important but often understudied.

OBJECTIVE

We sought to perform a cost-effectiveness analysis of 3 therapies for genitourinary syndrome of menopause, including vaginal estrogen therapy, oral ospemifene therapy, and vaginal CO₂ laser therapy and determine if vaginal laser therapy is a cost-effective treatment strategy for dyspareunia associated with genitourinary syndrome of menopause.

STUDY DESIGN

An institutional review board-exempt cost-effectiveness analysis was performed by constructing a decision tree using decision analysis software (TreeAge Pro; TreeAge Software, Inc, Williamstown, MA) using integrated empirical data from the published literature. Tornado plots and 1-way and 2-way sensitivity analyses were performed to assess how changes in the model's input parameters altered the overall outcome of the cost-effectiveness analysis model.

RESULTS

All 3 treatment methods were found to be cost-effective below the willingness-to-pay threshold of $50,000.00 per quality-adjusted life year for moderate dyspareunia. The incremental cost-effectiveness ratio for vaginal CO2 laser therapy was $16,372.01 and the incremental cost-effectiveness ratio for ospemifene therapy was $5711.14. Although all 3 treatment strategies were on the efficient frontier, vaginal CO₂ laser therapy was the optimal treatment strategy with the highest effectiveness. In a 1-way sensitivity analysis of treatment adherence, vaginal CO₂ laser therapy was no longer cost-effective when the adherence fell below 38.8%. Vaginal estrogen cream and ospemifene therapies remained cost-effective treatment strategies at all ranges of adherence. When varying the adherence to 100% for all strategies, oral ospemifene therapy was "dominated" by both vaginal CO₂ laser therapy and vaginal estrogen cream therapy. In a 2-way sensitivity analysis of vaginal CO₂ laser therapy adherence and vaginal CO₂ laser therapy cost, vaginal CO₂ laser therapy still remained the optimal treatment strategy at 200% of its current cost ($5554.00) when the adherence was >55%. When the cost fell to 20% of its current cost ($555.40), it was the optimal treatment strategy at all adherence values above 29%.

CONCLUSION

This study showed that vaginal fractional CO₂ laser therapy is a cost-effective treatment strategy for dyspareunia associated with GSM, as are both vaginal estrogen and oral ospemifene therapies. In our model, vaginal CO₂ laser therapy is the optimal cost-effective treatment strategy, and insurance coverage should be considered for this treatment option if it is proven to be safe and effective in FDA trials.

A phase 1b study evaluating the effect of elacestrant treatment on estrogen receptor availability and estradiol binding to the estrogen receptor in metastatic breast cancer lesions using 18F-FES PET/CT imaging

BACKGROUND

Elacestrant is an oral selective estrogen receptor (ER) degrader. This phase 1b open-label, non-randomized study (RAD1901-106) was initiated to determine the effect of elacestrant on the availability of ER in lesions from postmenopausal women with ER+ advanced breast cancer (ABC) using 16α-18F-fluoro-17β-estradiol positron emission tomography with low-dose computed tomography (FES-PET/CT).

METHODS

Eligible patients were postmenopausal women with ER+, HER2- ABC; tumor progression after ≥ 6 months of 1-3 lines of endocrine treatment for ABC; and measurable or evaluable disease. Two 8-patient cohorts were enrolled: one treated with 400 mg elacestrant once daily (QD) and one treated with 200 mg elacestrant QD with dose escalation to 400 mg QD after 14 days. Elacestrant was dosed continuously until progressive disease, toxicity, or withdrawal. FES-PET/CT was performed pre-dose at baseline and 4 h post-dose on day 14. The primary endpoint was the percentage difference in FES uptake in tumor lesions (maximum 20) after 14 days of treatment compared to baseline. Overall response was investigator-assessed by Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1.

RESULTS

Patients (n = 16; median age, 53.5 years) had ABC with a median 2.5 prior lines of endocrine therapy. Median reduction in tumor FES uptake from baseline to day 14 was 89.1% (Q1, Q3: 75.1%, 94.1%) and was similar in both cohorts (89.1% [Q1, Q3: 67.4%, 94.2%], 200/400 mg and 88.7% [Q1, Q3: 79.5%, 94.1%], 400 mg). Residual ER availability (> 25% persistence in FES uptake) on day 14 was observed in 3 patients receiving 200/400 mg (3/78, 37.5%) and 1 patient receiving 400 mg (1/8, 12.5%). The overall response rate (ORR) was 11.1% (1 partial response), and clinical benefit rate (CBR) was 30.8%. Median percentage change in FES uptake did not correlate with ORR or CBR. Adverse events occurring in > 20% of the patients were nausea (68.8%), fatigue (50.0%), dyspepsia (43.8%), vomiting (37.5%), and decreased appetite, dysphagia, and hot flush (31.3% each). Most events were grade 2 in severity.

CONCLUSION

Elacestrant 200 mg and 400 mg QD greatly reduced ER availability measured by FES-PET/CT. In a heavily pretreated population, elacestrant was associated with antitumor activity.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02650817 . Registered on 08 January 2016.

Estradiol, Progesterone, Immunomodulation, and COVID-19 Outcomes

Severe outcomes and death from the novel coronavirus disease 2019 (COVID-19) appear to be characterized by an exaggerated immune response with hypercytokinemia leading to inflammatory infiltration of the lungs and acute respiratory distress syndrome. Risk of severe COVID-19 outcomes is consistently lower in women than men worldwide, suggesting that female biological sex is instrumental in protection. This mini-review discusses the immunomodulatory and anti-inflammatory actions of high physiological concentrations of the steroids 17β-estradiol (E2) and progesterone (P4). We review how E2 and P4 favor a state of decreased innate immune inflammatory response while enhancing immune tolerance and antibody production. We discuss how the combination of E2 and P4 may improve the immune dysregulation that leads to the COVID-19 cytokine storm. It is intended to stimulate novel consideration of the biological forces that are protective in women compared to men, and to therapeutically harness these factors to mitigate COVID-19 morbidity and mortality.

Efficacy of a novel orally active SERD AZD9496 against hormone dependent post-menopausal breast cancer depends on inhibition of cellular aromatase activity

Treatment of hormone sensitive breast cancer tumors with endocrine therapy such as antiestrogens or aromatase inhibitors has improved the outcome significantly. Studies including our own have shown that downregulation of ERα with pure antiestrogen fulvestrant in combination with aromatase inhibitors may prolong responsiveness of the tumors to endocrine therapy. Fulvestrant has been studied as second line or first line treatment for post-menopausal hormone receptor positive breast cancers as a single agent or in combination with AIs. Studies have also suggested that further escalation of dose may improve benefit. However, dose escalation of fulvestrant, which is administered via intramuscular injection, is difficult due to its poor solubility. To overcome this shortcoming of an injectable drug, a novel orally active antiestrogen, AZD9496 was developed. In addition to being orally active, AZD9496 is designed as a selective ERα downregulator (SERD). In the current study, we compared the effect of AZD9496 and fulvestrant on the growth of MCF-7Ca (human estrogen receptor positive MCF-7 cells stably transfected with human placental aromatase gene) xenografts grown in ovariectomized athymic nude mice. AZD9496 was also compared to fulvestrant in vitro as a single agent or in combination with anastrozole. Our current study shows that AZD9496 is equally effective as fulvestrant at controlling the growth of hormone sensitive human breast cancer tumors. Similar to fulvestrant, AZD9496 inhibits cellular aromatase activity through ERα mediated signaling. However, unlike fulvestrant, combination of AZD9496 with anastrozole did not produce increased tumor inhibition. Our results show that AZD9496 was significantly better at inhibiting cellular aromatase which contributed to its anticancer activity. Next, we measured the effect of AZD9496 on the mouse uterus. Uterine weight of mice treated with AZD9496 was significantly lower than that for mice treated with androstenedione. This reduction in uterine weight was due to AZD9496 mediated inhibition of aromatase activity and not a direct effect on uterine ERα expression. We also observed that anti-cancer efficacy of AZD9496 depended on its ability to inhibit cellular aromatase. These results suggest that AZD9496 may be a better alternative to fulvestrant due to its selectivity for mammary ER and ability to inhibit aromatase in addition of downregulating ERα that can be obtained upon oral administration. As such, AZD9496 may prove to be a better option than fulvestrant for the treatment of hormone sensitive human breast cancer.