Estetrol review: profile and potential clinical applications

The effect of pregnancy-related hormones on hepatic transporters: studies with premenopausal human hepatocytes

Introduction

Pregnancy results in significant changes in drug pharmacokinetics (PK). While previous studies have elucidated the impact of pregnancy-related hormones (PRH) on mRNA or protein expression and activity of major hepatic metabolizing enzymes, their effect on hepatic drug transporters remains largely unexplored. Therefore, we investigated the effect of a cocktail of PRH on the mRNA expression and activity of hepatic transporters.

Methods

Plated human hepatocytes (PHH) from 3 premenopausal donors were incubated, in triplicate, for 72 h, with vehicle (DMSO < 0.01%), rifampin (10 μM; positive control) or a cocktail of PRH consisting of estrone, estradiol, estriol, estetrol, progesterone, cortisol, testosterone, oxytocin, and placental growth hormone. The PRH concentrations replicated 0.1×, 1×, or 10× of the plasma concentrations of these hormones observed during each of the three trimesters of pregnancy. After treatment, mRNA expression (quantified by qPCR) of hepatic influx and efflux transporters as well as the activity of influx transporters was quantified (uptake of a selective substrate ± corresponding transporter inhibitor). The data were expressed relative to that in the control (vehicle) group. Significance was evaluated by ANOVA (followed by Dunn's multiple comparisons) or unpaired t-test when the within-lot data were analyzed, or repeated measures ANOVA (followed by Dunn's multiple comparisons) or paired t-test when data from all 3 lots were analyzed (p < 0.05).

Results and Discussion

In general, a) PRH cocktails significantly induced transporter mRNA expression in the following order OAT2 ≈ NTCP ≈ OCT1 > OATP2B1 and repressed mRNA expression in the following order OATP1B3 > OATP1B1; b) these changes translated into significant induction of OAT2 (T1-T3) and NTCP (T2-T3, in only two lots) activity at the 1× PRH concentration. Compared with the influx transporters, the induction of mRNA expression of efflux transporters was modest, with mRNA expression of MRP2 and BSEP being induced the most.

Conclusion

Once these data are verified through in vivo probe drug PK studies in pregnancy, they can be populated into physiologically based pharmacokinetic (PBPK) models to predict, for all trimesters of pregnancy, transporter-mediated clearance of any drug that is a substrate of the affected transporters.

Oestrogens in oral contraception: considerations for tailoring prescription to women's needs

BACKGROUND

The oestrogenic component of combined oral contraceptives (COCs) has changed over years with the aim of reducing oestrogen-related side effects and risks, whilst maintaining oestrogen beneficial effects, particularly on cycle control.

PURPOSE

To describe the pharmacological profiles of different oestrogens commonly used in COCs to provide insights on contraceptive prescription tailored to women's needs.

RESULTS

All COCs ensure a high contraceptive efficacy. COCs containing the natural oestrogens oestradiol (E2), oestradiol valerate (E2V) and estetrol (E4) have limited impact on liver metabolism, lipid and carbohydrate metabolism, haemostasis and sex hormone binding globulin levels, compared with ethinylestradiol (EE). COCs with E2 and E2V appear also to entail a lower elevation of the risk of venous thromboembolism vs. EE-containing pills. No epidemiological data are available for E4-COC. E2- and E2V-containing COCs seem to exert a less stabilising oestrogenic effect on the endometrium compared with EE-COCs. The E4-COC results in a predictable bleeding pattern with a high rate of scheduled bleeding and minimal unscheduled bleeding per cycle. Based on in vitro and in vivo animal data, E4 seems to be associated with a lower effect on cell breast proliferation.

CONCLUSION

Today various COCs contain different oestrogens. Prescribers must be familiar with the different properties of each oestrogen for a tailored contraceptive recommendation, considering their safety and contraceptive efficacy, as well as women's needs and preferences.

The Loss of Estradiol by Androgen Deprivation in Prostate Cancer Patients Shows the Importance of Estrogens in Males

The role of estradiol (E2; an estrogen) in men needs to be more appreciated. In this review, we address the clinical situations that allow the study of the clinical consequences of E2 deficiency in men and discuss the effects of restoration of levels of this reproductive steroid hormone. In men with advanced prostate cancer (PCa) undergoing androgen deprivation therapy (ADT), E2 is suppressed along with testosterone, leading to side effects affecting the quality of life. These include hot flashes, arthralgia, fatigue, mood changes, cognition problems, weight gain, bone loss, and increased risk of cardiovascular disease. Transdermal E2 alone for ADT has shown equivalent testosterone suppression compared to gonadotropin-releasing hormone (GnRH) agonists while also preventing estrogen-deficiency side effects, including hot flashes and bone loss. Co-treatment of ADT with fetal estrogen estetrol (E4) has shown significant improvements of estrogen-deficiency symptoms. These observations emphasize the need to raise awareness of the importance of estrogens in men among clinicians and the lay public.

Estetrol Inhibits Endometriosis Development in an In Vivo Murine Model

Endometriosis is characterized by the growth of endometrial-like tissue outside the uterus, and it is associated with alterations in the expression of hormone receptors and inflammation. Estetrol (E4) is a weak estrogen that recently has been approved for contraception. We evaluated the effect of E4 on the growth of endometriotic-like lesions and the expression of TNF-α, estrogen receptors (ERs), and progesterone receptors (PRs) in an in vivo murine model. Endometriosis was induced surgically in female C57BL/6 mice. E4 was delivered via Alzet pump (3 mg/kg/day) from the 15th postoperative day for 4 weeks. E4 significantly reduced the volume (p < 0.001) and weight (p < 0.05) of ectopic lesions. Histologically, E4 did not affect cell proliferation (PCNA immunohistochemistry) but it did increase cell apoptosis (TUNEL assay) (p < 0.05). Furthermore, it modulated oxidative stress (SOD, CAT, and GPX activity, p < 0.05) and increased lipid peroxidation (TBARS/MDA, p < 0.01). Molecular analysis showed mRNA (RT-qPCR) and protein (ELISA) expression of TNF-α decreased (p < 0.05) and mRNA expression of Esr2 reduced (p < 0.05), in contrast with the increased expression of Esr1 (p < 0.01) and Pgr (p < 0.05). The present study demonstrates for the first time that E4 limited the development and progression of endometriosis in vivo.

Experts' view on the role of oestrogens in combined oral contraceptives: emphasis on oestetrol (E4)

Introduction

The evolution of contraception has been crucial for public health and reproductive well-being. Over the past 60 years, combined oral contraceptives (COCs) have remained an important part of the contraceptive landscape worldwide; continued development has worked toward maintaining efficacy and improving safety.

Methods

Seven global experts convened to discuss the clinical relevance of the oestrogen in COCs, focusing on the impact of the new oestrogen, oestetrol (E4). Participants then commented through an online forum on the summary content and other participants' feedback. We prepared this report to describe the experts' views, their follow-up from the open forum and the evidence supporting their views.

Results

Ethinylestradiol (EE) and oestradiol (E2) affect receptors similarly whereas E4 has differential effects, especially in the liver and breast. Adequate oestrogen doses in COCs ensure regular bleeding and user acceptability. EE and E4 have longer half-lives than E2; accordingly, COCs with EE and E4 offer more predictable bleeding than those with E2. Oestrogen type and progestin influence VTE risk; E2 poses a lower risk than EE; although promising, E4/DRSP VTE risk is lacking population-based data. COCs alleviate menstrual symptoms, impact mental health, cognition, libido, skin, and bone health.

Conclusion

Oestrogens play an important role in the contraceptive efficacy, bleeding patterns, and overall tolerability/safety of COCs. Recent studies exploring E4 combined with DRSP show promising results compared to traditional formulations, but more definitive conclusions await further research.

Comparison of estrogenic components used for hormonal contraception

Attempts have been made over the years to replace ethinyl estradiol (EE) in combined oral contraceptives (COCs) with the less potent natural estrogen estradiol (E2), or its prodrug, E2 valerate (E2V), to improve their safety and tolerability. Recently, a COC incorporating a novel weak natural estrogen, estetrol (E4), combined with drospirenone, has become available. We present a comparative analysis of the three prevailing estrogens used in COCs, focusing on their structure-function relationships, receptor-binding affinity, potency, metabolism, pharmacokinetic parameters, and pharmacodynamics. The binding affinity of EE to estrogen receptor (ER)α is twice that of E2, whereas its affinity for ERβ is about one-half that of E2. E4 has a lower binding affinity for the ERs than E2. The high potency of EE is notable in its dramatic increase in estrogen-sensitive hepatic globulins and coagulation factors. EE and E2 undergo extensive and comparable metabolism, while E4 produces only a very limited number of metabolites. E4 has the highest bioavailability among the three estrogens, with E2 having <5%. Studies demonstrate consistent ovulation inhibition, although a higher dose of E4 (15 mg) in COCs is required to achieve follicular suppression compared to E2 (1-3 mg) and EE (0.01-0.035 mg). E2 and E4 in COCs may be less stimulatory of coagulant proteins than EE. Studies with E2/dienogest suggest a comparable risk of venous thromboembolism to EE/levonorgestrel, while data assessing risk with an E4-based COC are insufficient. Nevertheless, the E4-based formulation shows promise as a potential alternative to EE and E2 due to its lower potency and possibly fewer side effects.

Impact of Estetrol Combined with Drospirenone on Blood Coagulation and Fibrinolysis in Patients with Endometriosis: A Multicenter, Randomized, Open-Label, Active-Controlled, Parallel-Group Study

Venous thromboembolism is a serious safety concern in women using combined oral contraceptives; ethinyl estradiol (EE) is widely used as an estrogen. Estetrol (E4) is a native estrogen with selective tissue activity and exclusively produced by the fetal liver. This study used a multicenter, randomized, open-label, active-controlled, parallel-group design to evaluate the effects of E4 combined with drospirenone (DRSP) on coagulation and fibrinolysis in Japanese patients with endometriosis. Participants were randomized to receive either E4 15 mg/DRSP 3 mg or EE 20 µg/DRSP 3 mg for 12 weeks. E4/DRSP and EE/DRSP were administered orally once a day in a cyclic regimen, ie, 24-day active use followed by a 4-day hormone-free period, and a flexible extended regimen, respectively, and blood coagulation and fibrinolysis markers were measured. The effect on coagulation and fibrinolysis was considerably less in the E4/DRSP group than in the EE/DRSP group. Major anticoagulant proteins, protein S (free, total) and tissue factor pathway inhibitor (free), were reduced following EE/DRSP treatment. Consequently, thrombin generation determined by the activated protein C sensitivity ratio was increased by approximately 4-fold in the EE/DRSP group than in the E4/DRSP group. Eventually, the fibrinolysis cascade was triggered to compensate for disturbed coagulation, and D-dimer levels were 4.7-fold higher in the EE/DRSP group than in the E4/DRSP group. This study demonstrated that the effect of E4/DRSP on the blood coagulation and fibrinolysis cascades was significantly less than that of EE/DRSP in participants with endometriosis, a disease of women of advanced and reproductive age (jRCT2080225090, https://jrct.niph.go.jp/en-latest-detail/jRCT2080225090).

Combined oral contraceptive with estetrol plus drospirenone: from pharmacokinetics to clinical applications

INTRODUCTION

Drospirenone/estetrol (DRSP/E4) is a combined oral contraceptive (COC) recently approved in several countries. It is composed of 15 mg of E4, a natural estrogen produced by human fetal liver throughout pregnancy, and 3 mg of DRSP, the first synthetic progestin used in oral contraception derived from 17-α-spirolactone. E4 and DRSP synergistically prevent pregnancy by inhibiting ovulation. E4 differs from 17-β-estradiol or ethinylestradiol because it represents a native estrogen with selective action in tissues (NEST), therefore it displays both agonist and antagonist estrogenic effects in different tissues.

AREAS COVERED

In this paper, we reviewed the scientific literature published in English prior to April 2023 and gathered information on the pharmacodynamics and pharmacokinetics of DRSP, E4 and their combination for contraception. We also proposed possible clinical applications based on the characteristics of the components of this COC.

EXPERT OPINION

E4/DRSP-based COC has shown high tolerability, safety and satisfaction and may represent a viable choice in young girls in need of oral contraception and pill users who suffer from high cholesterol, breast tenderness or water retention. Moreover, this new COC shows higher scheduled bleeding rate compared to other pills containing natural estrogens. All the data are reassuring, permitting long-term use.

The benefits of estetrol addition to drospirenone for contraception

Ethinylestradiol and drospirenone combined oral contraceptive formulations have been marketed for >20 years. Drospirenone has antimineralocorticoid and anti-androgenic effects that may offer several health benefits. Recently, 2 new drospirenone-containing oral contraceptives entered the market, 1 as a progestin-only pill containing 4 mg drospirenone and the other as a combined oral contraceptive containing 15 mg estetrol and 3 mg drospirenone. Estetrol has a unique differential effect on nuclear and membrane estrogen α-receptors when compared with other estrogens, leading to low impact on the liver, breast, and hemostasis parameters and a beneficial effect on the endometrium, vagina, cardiovascular system, bone, and brain. Phase 3 clinical studies demonstrated that the Pearl Index (pregnancies per 100-woman-years) for drospirenone alone is 4.0 in the United States and 0.93 in the European Union and for the estetrol-drospirenone combination it is 2.65 and 0.44, respectively. Drospirenone alone demonstrates high rates of unscheduled bleeding and low rates of scheduled bleeding, whereas the estetrol-drospirenone combination demonstrates a predictable and regular bleeding profile for most users with a high stable rate of scheduled bleeding and a low rate of unscheduled bleeding, reported primarily as spotting only. The adverse event profiles and discontinuation rates owing to adverse events are comparable, and no clinically significant effects were observed on metabolic parameters with either product. Hemostatic assays for drospirenone do not fully evaluate all parameters although the testing that is available suggests negligible effects, whereas validated hemostatic assays demonstrate that the estetrol-drospirenone combination has limited impact on hemostasis. The introduction of 4 mg drospirenone and 15 mg estetrol with 3 mg drospirenone are valuable additions to the contraceptive market. Adding estetrol to 3 mg drospirenone provides advantages of contraceptive efficacy and a regular, predictable bleeding profile with minimal impact on hemostasis parameters.

Drospirenone and estetrol: evaluation of a newly approved novel oral contraceptive

INTRODUCTION

Estetrol (E4) is a native estrogen produced only by the fetal liver during pregnancy. E4 is the first new estrogen to be used in hormonal contraception since the introduction of oral contraceptives in 1960. Ethinyl estradiol, the most commonly used estrogen in oral contraceptives today, increases the risks of thromboembolism and has other significant hepatic impacts, which induce important drug-drug interactions. On the other hand, Phase 2 E4 characterization studies demonstrated that E4 has negligible impacts on liver, breast, and vascular endothelium due to its distinct tissue selectivity. Combined with drospirenone (DRSP), E4 offers an improved safety profile for oral contraception.

AREAS COVERED

This paper briefly highlights the unique pharmacokinetic and pharmacodynamic features of E4. The efficacy, safety, and tolerability results from the Phase 2 and 3 studies of the E4/DRSP pill are discussed to provide the reader with a thorough understanding of E4 and information to use when counseling potential users.

EXPERT OPINION

The estetrol/drospirenone oral contraceptive is effective and well tolerated and provides good cycle control. In the future, estetrol may be the estrogen of choice if subsequent evidence verifies that it reduces the risks associated with current estrogens, such as venous thromboembolism and drug-drug interactions.

Biosynthesis of estetrol in human pregnancy: Potential pathways

Estetrol (E4) has emerged as a novel and highly promising estrogen for therapeutic use. E4 is a weak natural estrogen produced only in pregnancy. Because of its novelty, there is considerable interest by clinicians in how it is produced in pregnancy. Although the fetal liver plays a key role in its production, the placenta is also involved. A current view is that estradiol (E2) formed in the placenta enters the fetal compartment and is then rapidly sulfated. E2 sulfate then undergoes 15α-/16α-hydroxylation in the fetal liver thereby forming E4 sulfate (phenolic pathway). However, another pathway involving 15α,16α-dihydroxy-DHEAS formed in the fetal liver and converted to E4 in the placenta also plays a significant role (neutral pathway). It is not known which pathway predominates, but both pathways appear to be important in E4 biosynthesis. In this commentary, we summarize the well-established pathways in the formation of estrogens in the nonpregnant and pregnant female. We then review what is known about the biosynthesis of E4 and describe the 2 proposed pathways involving the fetus and placenta.

Regulation of human endothelial cell migration by oral contraceptive estrogen receptor ligands

Ethinylestradiol (EE) and estetrol (E4) are the two main estrogenic agents used in combined oral contraceptives. These compounds have different binding affinity to and efficacy on estrogen receptors (ER) subtypes. We previously reported that treatment with estrogenic agents enhances angiogenesis via nongenomic, G protein-coupled estrogen receptor (GPER)-dependent mechanisms. However, the impact of EE and E4 on human endothelial function has been little investigated. EE and E4 (10^-9- 10^-7 M) significantly enhanced migration of human umbilical vein endothelial cells (HUVECs) using scratch and Boyden chamber assays. Mechanistically, both agents increased accumulation of phosphorylated protein tyrosine kinase 2 on tyrosine 397 (FAK Y397), a key player in endothelial cell motility, after 30-min treatment. Treatment with increasing concentrations of EE, but not E4, enhanced accumulation of the glycolysis activator PFKFB3. Of note, effects of EE and E4 on endothelial migration and signalling proteins were abolished by addition of the GPER antagonist G36 (10^-6 M). Thus, EE and E4 induced comparable endothelial responses in vitro, suggesting no apparent alterations of vascular remodelling and regeneration capacity by oral contraceptives containing these agents.

Use of Liposome-encapsulated estetrol for treatment of Neonatal Hypoxic-Ischemic encephalopathy

Estetrol (E4) is a natural estrogen synthesized only during pregnancy. It has strong neuroprotective and antioxidative activities. The aim of the present study was to define the neuroprotective potency of E4 encapsulated either in liposome (Lipo-E4) or in drug-in cyclodextrin (HP-β-CD) in liposome (DCL) system, and compare them with a single use of E4. In vitro studies were performed in an oxidative stress model of primary hippocampal neuronal cell cultures, followed by the lactate dehydrogenase activity and cell proliferation assays. In vivo studies were conducted by using a model of neonatal hypoxic-ischemic encephalopathy in immature rat pups. Brain samples were studied by (immuno)histochemistry for the detection of survived cells, expression of microtubule-associated protein-2, myelin basic protein, doublecortin and vascular-endothelial growth factor. Concentrations of glial fibrillary acidic protein in blood serum were studied by ELISA. In vitro, cell proliferation was significantly up-regulated in cultures treated either by DCL-E4 or E4 compared to the control cells, whereas DCL-E4 treated cells had significantly higher survival rate than the cells treated by E4 alone. Evaluation of brain samples showed that DCL-E4 and a high dose of E4 alone significantly preserve the grey and the white matter loses, and diminish GFAP expression in blood. Although DCL-E4 and E4 have similar effect on neurogenesis in the hippocampus and the cortex, DCL-E4 treatment significantly up-regulates angiogenesis in the hippocampus compared to a single use of E4. Present work reveals for the first time that liposome-encapsulated E4 might be a better alternative to a single use of E4.

Impact of estetrol (E4) on hemostasis, metabolism and bone turnover in postmenopausal women

OBJECTIVE

This study aimed to determine the effects of estetrol (E4) on hemostasis, lipids, carbohydrate metabolism and bone turnover in postmenopausal women.

METHODS

This study was a multicenter, randomized, double-blind placebo-controlled phase 2 trial. Participants (n = 180, age 43-64 years) received E4 2.5 mg, 5 mg, 10 mg and 15 mg or placebo once daily for 12 weeks. Changes from baseline at week 12 were evaluated versus placebo for hemostasis parameters, sex hormone binding globulin (SHBG), lipids, carbohydrate metabolism and bone markers.

RESULTS

Changes for hemostasis parameters were minimal with a small increase only in the normalized activated protein C sensitivity ratio in the E4 15 mg group versus placebo. SHBG increased in the E4 5 mg, 10 mg and 15 mg groups versus placebo. High-density lipoprotein cholesterol increased in all E4 groups; changes were not consistent for other lipids. Significant decreases versus placebo were seen for insulin resistance (E4 10 mg group), hemoglobin A1c (E4 15 mg group) and type 1 collagen C-terminal telopeptide (E4 10 mg and 15 mg groups). Small decreases in osteocalcin in the E4 5 mg, 10 mg and 15 mg groups were significant versus the increase observed in placebo.

CONCLUSION

E4 had limited impact on hemostasis and potentially beneficial effects on lipids, carbohydrate metabolism and bone turnover.

Drugs for the treatment of postmenopausal symptoms: Hormonal and non-hormonal therapy

Postmenopausal symptoms are systemic symptoms associated with estrogen deficiency after menopause. At present, treatments for postmenopausal symptoms include hormonal therapy (HT) and non-HT. However, the optimal regimen for balancing the benefits and risks remains unclear. This article reviewed the characteristics, regimens, and side effects of drugs used in hormonal and non-HT. However, HT is still the most effective treatment with safety in early initiation since menopause onset. Nevertheless, it is essential to evaluate the risks of related chronic diseases and customize individualized treatments. Possible estetrol preparations and more types of Tissue Selective Estrogen Complex formulations are potential directions of drug development in the future of HT. Regarding non-HT, fezolinetant, currently in phase III clinical trials, is poised to become a first-in-class therapy for vasomotor symptoms. Ospemifene, dehydroepiandrosterone (DHEA), and vaginal lasers can also be used for moderate-to-severe genitourinary syndrome of menopause. Recent data suggest a superior efficacy and safety of vaginal lasers, but more validated evidence of long-term tolerability is needed to respond to the United States Food and Drug Administration warning. Herbal medication commonly used in Asia is effective in alleviating menopausal symptoms; however, its adverse effects still require more detailed reports and standardized observation methods. This review contributes to a better understanding of drugs for the treatment of postmenopausal symptoms and provides useful information for clinical drug selection.

Maintaining bone health by estrogen therapy in patients with advanced prostate cancer: a narrative review

The purpose of androgen deprivation therapy (ADT) in prostate cancer (PCa), using luteinizing hormone-releasing hormone agonists (LHRHa) or gonadotrophin-releasing hormone antagonists, is to suppress the levels of testosterone. Since testosterone is the precursor of estradiol (E2), one of the major undesired effects of ADT is the concomitant loss of E2, causing among others an increased bone turnover and bone loss and an increased risk of osteoporosis and fractures. Therefore, the guidelines for ADT indicate to combine ADT routinely with bone-sparing agents such as bisphosphonates, denosumab or selective estrogen receptor modulators. However, these compounds may have side effects and some require inconvenient parenteral administration. Co-treatment with estrogens is an alternative approach to prevent bone loss and at the same time, to avoid other side effects caused by the loss of estrogens, which is the topic explored in the present narrative review. Estrogens investigated in PCa patients include parenteral or transdermal E2, diethylstilbestrol (DES), and ethinylestradiol (EE) as monotherapy, or high-dose estetrol (HDE4) combined with ADT. Cardiovascular adverse events have been reported with parenteral E2, DES and EE. Encouraging effects on bone parameters have been obtained with transdermal E2 (tE2) and HDE4, in the tE2 development program (PATCH study), and in the LHRHa/HDE4 co-treatment study (PCombi), respectively. Confirmation of the beneficial effects of estrogen therapy with tE2 or HDE4 on bone health in patients with advanced PCa is needed, with special emphasis on bone mass and fracture rate.

Estetrol Prevents Hot Flushes and Improves Quality of Life in Patients with Advanced Prostate Cancer Treated with Androgen Deprivation Therapy: The PCombi Study

Background

Androgen deprivation therapy (ADT) for prostate cancer (PCa) is accompanied by side effects affecting health-related quality of life (HRQL).

Objective

To assess the effects of the fetal estrogen estetrol (E4) on symptoms related to estrogen and androgen deficiency, and on HRQL measured using the validated Functional Assessment of Cancer Therapy-Prostate (FACT-P) questionnaire.

Design, setting, and participants

This was a phase 2, double-blind, randomized, placebo-controlled study in patients with advanced PCa.

Intervention

Patients receiving ADT were randomly assigned at a 2:1 ratio to daily treatment with a high dose of E4 (HDE4; n = 41) or placebo (n = 21) for 24 wk.

Outcome measurements and statistical analysis

The primary outcome was the effect of HDE4 cotreatment on hot flushes (HFs). Secondary outcomes were the Q-Man questionnaire for evaluation of the effect on estrogen and androgen deficiency symptoms, and the FACT-P questionnaire for evaluating HRQL.

Results and limitations

At 24 wk, the number of patients experiencing HFs was significantly lower in the HDE4 group than in the placebo group (14.3% vs 60.0%; p < 0.001). HDE4 treatment was associated with lower incidence of night sweats, arthralgia, and fatigue, but more nipple tenderness and gynecomastia. At 24 wk, the mean HRQL score favored HDE4 over placebo for the FACT-P total score (122.2 ± 12.3 vs 118.7 ± 19.7) and for several other FACT subscales.

Conclusions

Daily HDE4 coadministration almost completely prevented HFs in patients with advanced PCa treated with ADT. HDE4 also had positive effects on HRQL and counteracted other estrogen deficiency symptoms caused by ADT. These data support the dual efficacy concept of ADT and HDE4 to improve HRQL and increase the antitumor effect of ADT.

Patient summary

For patients on androgen deprivation therapy for advanced prostate cancer, cotreatment with a high dose of estetrol almost completely prevents the occurrence of hot flushes and improves quality of life and well-being, but nipple sensitivity and an increase in breast size may occur.

A novel estetrol-containing combined oral contraceptive: European expert panel review

PURPOSE

Despite considerable advances in recently developed combined oral contraceptives (COCs), resulting in lower rates of adverse events while maintaining contraceptive efficacy, there is interest in further innovation.

MATERIALS AND METHODS

Estetrol (E4), a native oestrogen, and progestin drospirenone (DRSP) were combined in a new COC. A European expert panel reviewed the pharmacology, efficacy, and safety and tolerability of this combination. Their findings are presented as a narrative review.

RESULTS

E4 15mg/DRSP 3 mg in a 24/4 regimen provided effective contraception with good cycle control, characterised by a predictable regular bleeding pattern and minimal unscheduled bleeding, together with a good safety profile. The combination was associated with high user satisfaction, wellbeing, and minimal changes in body weight. The effects on endocrine and metabolic parameters were limited, and the combination was found to have a limited impact on liver function and lipid and carbohydrate metabolism. Moreover, its effect on several haemostatic parameters was lower than that of comparators containing ethinyl oestradiol (EE) 20mg/DRSP 3 mg and EE 30mg/levonorgestrel 150mg.

CONCLUSION

E4 15 mg/DRSP 3 mg provides safe and effective contraception, with high user satisfaction and predictable bleeding. Further research will evaluate the long-term safety of the COC.

Profile of estetrol, a promising native estrogen for oral contraception and the relief of climacteric symptoms of menopause

INTRODUCTION

Estrogens used in women's healthcare have been associated with increased risks of venous thromboembolism (VTE) and breast cancer. Estetrol (E4), an estrogen produced by the human fetal liver, has recently been approved for the first time as a new estrogenic component of a novel combined oral contraceptive (E4/drospirenone [DRSP]) for over a decade. In phase 3 studies, E4/DRSP showed good contraceptive efficacy, a predictable bleeding pattern, and a favorable safety and tolerability profile.

AREAS COVERED

This narrative review discusses E4's pharmacological characteristics, mode of action, and the results of preclinical and clinical studies for contraception, as well as for menopause and oncology.

EXPERT OPINION

Extensive studies have elucidated the properties of E4 that underlie its favorable safety profile. While classical estrogens (such as estradiol) exert their actions via both activation of nuclear and membrane estrogen receptor α (ERα), E4 presents a specific profile of ERα activation: E4 binds and activates nuclear ERα but does not induce the activation of membrane ERα signaling pathways in specific tissues. E4 has a small effect on normal breast tissue proliferation and minimally affects hepatic parameters. This distinct profile of ERα activation, uncoupling nuclear and membrane activation, is unique.

A Clinical Review on Paroxetine and Emerging Therapies for the Treatment of Vasomotor Symptoms

Most women experience vasomotor symptoms (VMS) during their menopausal transition. Menopausal hormone therapy (HT) is the most effective treatment for VMS, but some women choose not to use HT or have contraindications to using HT. Non-hormonal treatment options should be offered to these symptomatic menopausal women. Multiple large randomized controlled trials have demonstrated statistically significant reductions in hot flash severity and/or frequency with the use of selective serotonin reuptake inhibitors (SSRIs) and serotonin norepinephrine reuptake inhibitors (SNRIs). To date, paroxetine mesylate remains the only non-hormonal treatment that has been approved by the United States Food and Drug Administration (FDA) for the management of moderate to severe postmenopausal vasomotor symptoms. Lower doses are needed to reduce VMS than those used to treat anxiety or depression, which is beneficial since side effects are typically dose dependent. The recommended dosage is 7.5 mg once daily at bedtime. Dose dependent side effects include nausea, fatigue, and dizziness. Knowing potential medication interactions is critical such as with medications that can lead to serotonin syndrome, concomitant use with monoamine oxidase inhibitors and being aware of p450 drug metabolism is essential for patients taking drugs that utilize the CYP2D6 enzyme for metabolism including tamoxifen. This review discusses in detail the available data supporting the use of paroxetine for the treatment of VMS, including side effects and considerations regarding prescribing. A discussion of other emerging treatments is included as well, including estetrol, oxybutynin and neurokinin 3 (NK3) receptor antagonists.

Combined Oral Contraceptives and Venous Thromboembolism: Review and Perspective to Mitigate the Risk

Many factors must be considered and discussed with women when initiating a contraceptive method and the risk of venous thromboembolism (VTE) is one of them. In this review, we discuss the numerous strategies that have been implemented to reduce the thrombotic risk associated with combined oral contraceptives (COCs) from their arrival on the market until today. Evidences suggesting that COCs were associated with an increased risk of VTE appeared rapidly after their marketing. Identified as the main contributor of this risk, the dosage of the estrogen, i.e., ethinylestradiol (EE), was significantly reduced. New progestins were also synthetized (e.g., desogestrel or gestodene) but their weak androgenic activity did not permit to counterbalance the effect of EE as did the initial progestins such as levonorgestrel. Numerous studies assessed the impact of estroprogestative combinations on hemostasis and demonstrated that women under COC suffered from resistance towards activated protein C (APC). Subsequently, the European Medicines Agency updated its guidelines on clinical investigation of steroid contraceptives in which they recommended to assess this biological marker. In 2009, estradiol-containing COCs were marketed and the use of this natural form of estrogen was found to exert a weaker effect on the synthesis of hepatic proteins compared to EE. In this year 2021, a novel COC based on a native estrogen, i.e., estetrol, will be introduced on the market. Associated with drospirenone, this preparation demonstrated minor effects on coagulation proteins as compared with other drospirenone-containing COCs. At the present time, the standard of care when starting a contraception, consists of identifying the presence of hereditary thrombophilia solely on the basis of familial history of VTE. This strategy has however been reported as poorly predictive of hereditary thrombophilia. One rationale and affordable perspective which has already been considered in the past could be the implementation of a baseline screening of the prothrombotic state to provide health care professionals with objective data to support the prescription of the more appropriate contraceptive method. While this strategy was judged too expensive due to limited laboratory solutions, the endogenous thrombin potential-based APC resistance assay could now represent an interesting alternative.

Oestrogen component of COCs: have we finally found a replacement for ethinyl estradiol?

PURPOSE OF REVIEW

Combined oral contraceptive pills are among the most widely used contraceptive methods globally. Despite their popularity, the potential risks and side effects can lead to both high discontinuation rates and adverse outcomes including thromboembolic events. The quest for a safer alternative to the traditional ethinyl estradiol/progestin combination has led to the use of newer oestrogens. Ethinyl oestradiol alternatives will be reviewed including the newest option, estetrol, as it enters clinical use.

RECENT FINDINGS

Oestradiol, when combined with a progestin with strong endometrial activity, is a viable alternative to ethinyl estradiol in the form of oestradiol valerate and estradiol, which have been available since 2008 and 2011, respectively. Estetrol is the newest oestrogen available and is found naturally in the foetal liver. Estetrol was approved for use in 2021. All three of these alternatives have high contraceptive efficacy, similar if not improved cycle control and decreased impact on haemostatic factors as compared to ethinyl estradiol.

SUMMARY

Alternatives to ethinyl oestradiol, including the newest option of estetrol, show promise in providing comparable contraceptive efficacy with potentially lower risk of side effects and thromboembolic events.

Estetrol: A New Choice for Contraception

Estetrol (E4) is a natural estrogenic steroid that is normally produced by human fetal liver. Recent research has demonstrated that it is a potent, orally bioavailable, natural selective estrogen receptor modulator; it has a moderate affinity for both human estrogen receptor alpha (ERα) and ERβ, with a preference for ERα. Clinical studies have demonstrated possible use as an estrogen in combined oral contraceptives (COC). COCs containing E4 and drospirenone (DRSP) showed a high acceptability, tolerability, and user satisfaction also when compared to COCs containing ethinylestradiol (EE). E4/DRSP effectively inhibits ovulation, with a similar effect on endometrium thickness than that of EE-containing COCs. Low doses (15 mg) of E4 with DRSP (3 mg) showed promising results in term of bleeding pattern and cycle control, also when compared to other COCs containing synthetic estrogens. Moreover, the association has limited effects on serum lipids, liver, SHBG levels, and carbohydrate metabolism. This combination also could drive a lower risk of venous thromboembolism than EE-containing COCs. In this review, we will summarize the actual knowledge about the new E4-containing contraceptive. Further large-scale studies in the full target population are needed to provide more insights into the cardiovascular safety profile and user satisfaction of E4/DRSP.

Estrogens and the regulation of glucose metabolism

The main estrogens: estradiol, estrone, and their acyl-esters have been studied essentially related to their classical estrogenic and pharmacologic functions. However, their main effect in the body is probably the sustained control of core energy metabolism. Estrogen nuclear and membrane receptors show an extraordinary flexibility in the modulation of metabolic responses, and largely explain gender and age differences in energy metabolism: part of these mechanisms is already sufficiently known to justify both. With regard to energy, the estrogen molecular species act essentially through four key functions: (1) Facilitation of insulin secretion and control of glucose availability; (2) Modulation of energy partition, favoring the use of lipid as the main energy substrate when more available than carbohydrates; (3) Functional protection through antioxidant mechanisms; and (4) Central effects (largely through neural modulation) on whole body energy management. Analyzing the different actions of estrone, estradiol and their acyl esters, a tentative classification based on structure/effects has been postulated. Either separately or as a group, estrogens provide a comprehensive explanation that not all their quite diverse actions are related solely to specific molecules. As a group, they constitute a powerful synergic action complex. In consequence, estrogens may be considered wardens of energy homeostasis.

Estetrol and Mammary Gland: Friends or Foes?

Estrogens have pleiotropic effects on many reproductive and non-reproductive tissues and organs including the mammary gland, uterus, ovaries, vagina, and endothelium. Estrogen receptor α functions as the principal mediator of estrogenic action in most of these tissues. Estetrol (E4) is a native fetal estrogen with selective tissue actions that is currently approved for use as the estrogen component in a combined oral contraceptive and is being developed as a menopause hormone therapy (MHT, also known as hormone replacement therapy). However, exogenous hormonal treatments, in particular MHTs, have been shown to promote the growth of preexisting breast cancers and are associated with a variable risk of breast cancer depending on the treatment modality. Therefore, evaluating the safety of E4-based formulations on the breast forms a crucial part of the clinical development process. This review highlights preclinical and clinical studies that have assessed the effects of E4 and E4-progestogen combinations on the mammary gland and breast cancer, focusing in particular on the estrogenic and anti-estrogenic properties of E4. We discuss the potential advantages of E4 over current available estrogen-formulations as a contraceptive and for the treatment of symptoms due to menopause. We also consider the potential of E4 for the treatment of endocrine-resistant breast cancer.

Natural estrogens enhance the engraftment of human hematopoietic stem and progenitor cells in immunodeficient mice

Hematopoietic Stem and Progenitor Cells are crucial in the maintenance of lifelong production of all blood cells. These Stem Cells are highly regulated to maintain homeostasis through a delicate balance between quiescence, self-renewal and differentiation. However, this balance is altered during the hematopoietic recovery after Hematopoietic Stem and Progenitor Cell Transplantation. Transplantation efficacy can be limited by inadequate Hematopoietic Stem Cells number, poor homing, low level of engraftment, or limited self-renewal. As recent evidences indicate that estrogens are involved in regulating the hematopoiesis, we sought to examine whether natural estrogens (estrone or E1, estradiol or E2, estriol or E3 and estetrol or E4) modulate human Hematopoietic Stem and Progenitor Cells. Our results show that human Hematopoietic Stem and Progenitor Cell subsets express estrogen receptors, and whose signaling is activated by E2 and E4 on these cells. Additionally, these natural estrogens cause different effects on human Progenitors in vitro. We found that both E2 and E4 expand human Hematopoietic Stem and Progenitor Cells. However, E4 was the best tolerated estrogen and promoted cell cycle of human Hematopoietic Progenitors. Furthermore, we identified that E2 and, more significantly, E4 doubled human hematopoietic engraftment in immunodeficient mice without altering other Hematopoietic Stem and Progenitor Cells properties. Finally, the impact of E4 on promoting human hematopoietic engraftment in immunodeficient mice might be mediated through the regulation of mesenchymal stromal cells in the bone marrow niche. Together, our data demonstrate that E4 is well tolerated and enhances human reconstitution in immunodeficient mice, directly by modulating human Hematopoietic Progenitor properties and indirectly by interacting with the bone marrow niche. This application might have particular relevance to ameliorate the hematopoietic recovery after myeloablative conditioning, especially when limiting numbers of Hematopoietic Stem and Progenitor Cells are available.

Estetrol Cotreatment of Androgen Deprivation Therapy in Infiltrating or Metastatic, Castration-sensitive Prostate Cancer: A Randomized, Double-blind, Phase II Trial (PCombi)

BACKGROUND

Androgen deprivation therapy (ADT) for prostate cancer with luteinizing hormone-releasing hormone (LHRH) agonists can be improved.

OBJECTIVE

To assess safety, the frequency and severity of hot flushes (HFs), bone health, and antitumor effects of high-dose estetrol (HDE4) when combined with ADT.

DESIGN SETTING AND PARTICIPANTS

A phase II, double-blind, randomized, placebo-controlled study was conducted in advanced prostate cancer patients requiring ADT (the PCombi study).

INTERVENTION

Patients receiving LHRH agonist treatment were randomized 2:1 to 40 mg HDE4 (n = 41) or placebo (n = 21) cotreatment for 24 wk.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Coprimary endpoints were frequency/severity of HFs and levels of total and free testosterone (T). Secondary endpoints included assessments of bone metabolism (osteocalcin and type I collagen telopeptide [CTX1]), prostate-specific antigen (PSA), and follicle-stimulating hormone (FSH). Efficacy analysis was based on the selected per-protocol (PP) population.

RESULTS AND LIMITATIONS

Of 62 patients included in the study, 57 were suitable for a PP analysis (37 HDE4; 20 placebo). No E4-related serious cardiovascular adverse events occurred at 24 wk. Weekly HFs were reported by 13.5% of patients with HDE4 and 60.0% with placebo (p < 0.001). Daily HFs occurred in 5.9% versus 55%. Bone turnover parameters decreased significantly with HDE4 (p < 0.0001). Total and free T decreased earlier (p < 0.05), and free T was suppressed further (p < 0.05). PSA suppression was more profound and earlier (p < 0.005). FSH levels were suppressed by 98% versus 57% (p < 0.0001). Estrogenic side effects were nipple sensitivity (34%) and gynecomastia (17%).

CONCLUSIONS

HDE4 cotreatment of ADT patients with advanced prostate cancer was well tolerated, and no treatment-related cardiovascular adverse events were observed at 24 wk. HFs and bone turnover were substantially reduced. Suppression of free T, PSA, and FSH was more rapid and profound, suggesting enhanced disease control by HDE4 cotreatment. Larger and longer-lasting studies are needed to confirm the results of the study reported here.

PATIENT SUMMARY

Cotreatment of androgen deprivation therapy with high-dose estetrol in advanced prostate cancer patients results in fewer occurrences of hot flushes, bone protection, and other antitumor benefits. Nipple sensitivity and gynecomastia may occur as side effects.

Pharmacotherapeutic options for the treatment of menopausal symptoms

Introduction: Menopausal symptoms can be very overwhelming for women. Over the years, many pharmacotherapeutic options have been tested, and others are still being developed. Hormone therapy (HT) is the most efficient therapy for managing vasomotor symptoms and related disturbances. The term HT comprises estrogens and progestogens, androgens, tibolone, the tissue-selective estrogen complex (TSEC), a combination of bazedoxifene and conjugated estrogens, and the selective estrogen receptor modulators, such as ospemifene. Estrogens and progestogens and androgens may differ significantly for chemical structure and can be delivered through different routes, thereby displaying various pharmacological and clinical properties. Tibolone, TSEC and SERM also exhibit unique pharmacodynamics that can be exploited to obtain distinctive therapeutic effects. Non-hormonal options fall mainly into the selective serotonin reuptake inhibitor (SSRI) and selective noradrenergic reuptake inhibitor (SNRI), GABA-analogue drug classes.Areas covered: Herein, the authors describe the pharmacokinetics and pharmacodynamics of hormonal (androgens, estrogens, progestogens, tibolone, TSEC, SERMs) and non-hormonal (SSRIs, SNRIs, Gabapentin, Pregabalin, Oxybutynin, Neurokinin antagonists) treatments for menopausal symptoms and report essential clinical trial data in humans.Expert opinion: Patient tailoring of treatment is key to managing symptoms of menopause. Physicians must have in-depth knowledge of the pharmacology of compounds to tailor therapy to the individual patient's characteristics and needs.

Effects of an oral contraceptive containing estetrol and drospirenone on ovarian function

OBJECTIVE

To evaluate the effects of estetrol 15 mg/drospirenone 3 mg on ovarian function.

STUDY DESIGN

Single-center, randomized, open-label, parallel study in healthy young women with proven ovulatory cycles. Participants received either estetrol 15 mg/drospirenone 3 mg (E4/DRSP) (n = 41) or ethinylestradiol 20 µg/drospirenone 3 mg (EE/DRSP) (n = 41) in a 24/4-day regimen for 3 consecutive cycles. Follicular size and endometrial thickness were measured by transvaginal ultrasound every 3 days in cycles 1 and 3. Blood was sampled for hormone analysis. Ovarian function expressed as Hoogland score was based on follicular size, serum estradiol (E2) and progesterone (P) concentrations. Ovulation was defined as a ruptured follicle-like structure >13 mm with serum E2 concentrations >100 pmol/L and serum P concentrations >5 nmol/L. We assessed return of ovulation after treatment cessation, and safety throughout the study.

RESULTS

None of the participants ovulated with E4/DRSP use, while one participant ovulated once and one participant ovulated twice during EE/DRSP treatment. Most participants had a Hoogland score of 1 (no ovarian activity) in cycle 1 (85.0% and 82.9% of participants on E4/DRSP and EE/DRSP, respectively) and in cycle 3 (65.8% and 83.8%, respectively). E4/DRSP suppressed follicle-stimulating hormone and luteinizing hormone to a lesser extent than EE/DRSP, whereas both treatments comparably suppressed E2 and P and endometrial thickness. Return of ovulation occurred, on average, 15.5 days after E4/DRSP treatment discontinuation. E4/DRSP was safe and well-tolerated.

CONCLUSIONS

E4 15 mg/DRSP 3 mg results in adequate ovulation inhibition and ovarian function suppression, comparable to a marketed combined oral contraceptive containing EE/DRSP.

IMPLICATIONS STATEMENT

Treatment with E4 15 mg/DRSP 3 mg showed complete ovulation inhibition, despite less suppression of follicle-stimulating hormone and luteinizing hormone compared to EE/DRSP. If it becomes commercially available, E4/DRSP, containing a naturally occurring estrogen, should be as effective as EE/DRSP.

Critical Role of Estrogens on Bone Homeostasis in Both Male and Female: From Physiology to Medical Implications

Bone is a multi-skilled tissue, protecting major organs, regulating calcium phosphate balance and producing hormones. Its development during childhood determines height and stature as well as resistance against fracture in advanced age. Estrogens are key regulators of bone turnover in both females and males. These hormones play a major role in longitudinal and width growth throughout puberty as well as in the regulation of bone turnover. In women, estrogen deficiency is one of the major causes of postmenopausal osteoporosis. In this review, we will summarize the main clinical and experimental studies reporting the effects of estrogens not only in females but also in males, during different life stages. Effects of estrogens on bone involve either Estrogen Receptor (ER)α or ERβ depending on the type of bone (femur, vertebrae, tibia, mandible), the compartment (trabecular or cortical), cell types involved (osteoclasts, osteoblasts and osteocytes) and sex. Finally, we will discuss new ongoing strategies to increase the benefit/risk ratio of the hormonal treatment of menopause.

Astrocytoma: A Hormone-Sensitive Tumor?

Astrocytomas and, in particular, their most severe form, glioblastoma, are the most aggressive primary brain tumors and those with the poorest vital prognosis. Standard treatment only slightly improves patient survival. Therefore, new therapies are needed. Very few risk factors have been clearly identified but many epidemiological studies have reported a higher incidence in men than women with a sex ratio of 1:4. Based on these observations, it has been proposed that the neurosteroids and especially the estrogens found in higher concentrations in women's brains could, in part, explain this difference. Estrogens can bind to nuclear or membrane receptors and potentially stimulate many different interconnected signaling pathways. The study of these receptors is even more complex since many isoforms are produced from each estrogen receptor encoding gene through alternative promoter usage or splicing, with each of them potentially having a specific role in the cell. The purpose of this review is to discuss recent data supporting the involvement of steroids during gliomagenesis and to focus on the potential neuroprotective role as well as the mechanisms of action of estrogens in gliomas.

Computer-Aided Ligand Discovery for Estrogen Receptor Alpha

Breast cancer (BCa) is one of the most predominantly diagnosed cancers in women. Notably, 70% of BCa diagnoses are Estrogen Receptor α positive (ERα+) making it a critical therapeutic target. With that, the two subtypes of ER, ERα and ERβ, have contrasting effects on BCa cells. While ERα promotes cancerous activities, ERβ isoform exhibits inhibitory effects on the same. ER-directed small molecule drug discovery for BCa has provided the FDA approved drugs tamoxifen, toremifene, raloxifene and fulvestrant that all bind to the estrogen binding site of the receptor. These ER-directed inhibitors are non-selective in nature and may eventually induce resistance in BCa cells as well as increase the risk of endometrial cancer development. Thus, there is an urgent need to develop novel drugs with alternative ERα targeting mechanisms that can overcome the limitations of conventional anti-ERα therapies. Several functional sites on ERα, such as Activation Function-2 (AF2), DNA binding domain (DBD), and F-domain, have been recently considered as potential targets in the context of drug research and discovery. In this review, we summarize methods of computer-aided drug design (CADD) that have been employed to analyze and explore potential targetable sites on ERα, discuss recent advancement of ERα inhibitor development, and highlight the potential opportunities and challenges of future ERα-directed drug discovery.

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.

Trastuzumab in the Treatment of Pregnant Breast Cancer Patients - an Overview of the Literature

Breast cancer is one of the most common malignancies which appear during pregnancy. Since women are increasingly not giving birth until they are at a more advanced age, it can be assumed that the incidence of pregnancy-related breast cancers will continue to increase in the future. Because of pregnancy-induced changes and conservative diagnosis, these carcinomas are frequently not detected until they are at an advanced stage and thus generally require systemic adjuvant therapy. The available data on optimal chemotherapeutic management are limited. Particularly for the use of the target agent trastuzumab which could crucially contribute to improving the prognosis in the therapy of HER2-overexpressing breast cancer in non-pregnant women, there is a lack of definitive information regarding the profile of action and safety in pregnancy as well as with regard to any long-term effects on the child. Thirty-eight pregnancies on trastuzumab for the treatment of breast cancer were able to be analysed in the literature currently available. Information can be gained from this and conclusions can be drawn which can individualise and decisively improve therapeutic options in the future for the pregnant breast cancer patient.

Pro-Apoptotic Effects of Estetrol on Long-Term Estrogen-Deprived Breast Cancer Cells and at Low Doses on Hormone-Sensitive Cells

Purpose:

Postmenopausal women with estrogen receptor-positive breast cancers often respond initially to tamoxifen or aromatase inhibitor therapy. Resistance to these treatments usually develops within 12 to 18 months. Clinical studies have demonstrated that high-dose estrogen can induce regression of these endocrine-resistant tumors. However, side-effects of high-dose estradiol (E₂) or diethylstilbestrol (DES) limit their usage. Estetrol (E₄) is the most abundant estrogen during pregnancy and has a long half-life and a low potential for side-effects. Estetrol might then provide benefits similar to DES on tumor regression but with lesser toxicity.

Methods:

In this study, we systematically evaluated the effects of E₄ on cell proliferation and apoptosis in wild-type MCF-7 and long-term estrogen-deprived (LTED) MCF-7 cells and compared its effects with E₂ and estriol (E₃).

Results:

Estetrol induced apoptosis in LTED cells but stimulated growth of MCF-7 cells at concentrations from 10⁻¹¹ to 10⁻⁸ M. These effects of E₄ are similar to those of E₂ but require much higher doses. Differing from E₂, E₄ at 10⁻¹² M induced apoptosis in MCF-7 cells and another pregnancy estrogen, E₃, acted similarly. No antagonistic effect of E₄ or E₃ against E₂ occurred when they were combined.

Conclusions:

The pro-apoptotic effects of E₄ and E₃ on LTED cells and at low doses on MCF-7 cells indicate that these steroids could be used as therapeutic agents for endocrine-resistant or sensitive breast cancer.

Menopause hormone therapy: latest developments and clinical practice

Menopause hormone therapy (MHT) is the most efficient treatment for symptoms of acute climacteric syndrome and for efficient prevention of long-term estrogen deficiency. Vaginal administration of low doses of estrogen is a therapy of choice for treatment and prevention of urogenital atrophy and its consequences. Systemic treatment may include estrogen, but an equally efficient alternative is tibolone. Nonhormonal therapy relies on phytoestrogens, black cohosh extract, and serotonin reuptake inhibitors.

Effect of estetrol, a selective nuclear estrogen receptor modulator, in mouse models of arterial and venous thrombosis

Estetrol (E4) is a natural estrogen synthesized exclusively during pregnancy by the human fetal liver, and the physiological role of this hormone is unknown. Interestingly, E4 was recently evaluated in preclinical and phase II-III clinical studies in combination with a progestin, with the advantage to not increase the circulating level of coagulation factors, at variance to oral estradiol or ethinylestradiol. Here, we evaluated the effect of E4 on hemostasis and thrombosis in mouse. Following chronic E4 treatment, mice exhibited a prolonged tail-bleeding time and were protected from arterial and also venous thrombosis in vivo. In addition, E4 treatment decreased ex vivo thrombus growth on collagen under arterial flow conditions. We recently showed that E4 activates uterine epithelial proliferation through nuclear estrogen receptor (ER) α. To analyze the impact of nuclear ERα actions on hemostasis and thrombosis, we generated hematopoietic chimera with bone marrow cells deficient for nuclear ERα. E4-induced protection against thromboembolism was significantly reduced in the absence of hematopoietic nuclear ERα activation, while the increased tail-bleeding time was not impacted by this deletion. In addition to its "liver friendly" profile described in women, our data shows that E4 has anti-thrombotic properties in various mouse models. Altogether, the natural fetal estrogen E4 could represent an attractive alternative to classic estrogens in oral contraception and treatment of menopause.

Towards optimization of estrogen receptor modulation in medicine

Women now spend more than one-third of their lives in the postmenopausal years, and the decline of endogenous estrogen production during menopause is accompanied by a series of functional disorders that affect the quality of life. These symptoms could be alleviated or even totally suppressed by menopausal hormone therapy (MHT), initially based on natural estrogens extracted from the urine of pregnant mares (mainly in the USA, using the oral route) and later from the synthesis of the natural estrogen, 17β-estradiol (mainly in Europe, in particular using the transdermal route). Estrogen receptor (ER) α is the main receptor mediating the physiological effects of estrogens. ERα belongs to the nuclear receptor superfamily and activates gene transcription in a time and tissue-specific manner through two distinct activation functions (AF), AF1 and AF2. In addition to these classical genomic actions, ERα also mediates membrane initiated signaling enabling rapid actions of estrogen, potentially along or in interaction with other receptors. Here, we provide a brief historical overview of MHT, and we then highlight recent advances in the characterization of new treatments based on the association of estrogens with selective estrogen receptor modulators (SERMs) or on the modulation of nuclear or membrane ERα.

Pharmacodynamic effects of the fetal estrogen estetrol in postmenopausal women: results from a multiple-rising-dose study

OBJECTIVE

Estetrol (E4) is an estrogen produced exclusively by the human fetal liver during pregnancy. In this study the pharmacodynamic effects of escalating doses of E4 in postmenopausal women were investigated.

METHODS

This was a partly randomized, open-label, multiple-rising-dose study in 49 postmenopausal women. Participants were randomized to receive either 2 mg E4 or 2 mg estradiol-valerate (E2 V) for 28 days. Subsequent dose-escalation groups were (non-randomized): 10, 20 and 40 mg E4. Blood samples were collected regularly for measuring endocrine and hemostasis variables, lipids and lipoproteins, fasting glucose and bone turnover markers.

RESULTS

Estetrol treatment resulted in a decrease of follicle-stimulating hormone and luteinizing hormone and an increase of sex-hormone binding globulin. Changes in hemostasis variables were small. A lowering effect on low-density lipoprotein cholesterol was accompanied with an increase in high-density lipoprotein cholesterol and no or minimal changes in triglycerides. The considerable decrease in osteocalcin levels in the three highest E4 dose groups and the small decrease in C-telopeptide levels were comparable to the E2 V control group and suggest a preventive effect on bone loss. All changes observed were dose-dependent.

CONCLUSIONS

In this study, estetrol treatment showed dose-dependent estrogenic effects on endocrine parameters, bone turnover markers, and lipids and lipoproteins. The effect on triglycerides was small as were the effects on hemostatic variables. These results support the further investigation of estetrol as a candidate for hormone therapy. Quantitatively, the effects of 10 mg estetrol were similar to the study comparator 2 mg estradiol valerate.

G protein-coupled estrogen receptor regulates embryonic heart rate in zebrafish

Estrogens act by binding to estrogen receptors alpha and beta (ERα, ERβ), ligand-dependent transcription factors that play crucial roles in sex differentiation, tumor growth and cardiovascular physiology. Estrogens also activate the G protein-coupled estrogen receptor (GPER), however the function of GPER in vivo is less well understood. Here we find that GPER is required for normal heart rate in zebrafish embryos. Acute exposure to estrogens increased heart rate in wildtype and in ERα and ERβ mutant embryos but not in GPER mutants. GPER mutant embryos exhibited reduced basal heart rate, while heart rate was normal in ERα and ERβ mutants. We detected gper transcript in discrete regions of the brain and pituitary but not in the heart, suggesting that GPER acts centrally to regulate heart rate. In the pituitary, we observed gper expression in cells that regulate levels of thyroid hormone triiodothyronine (T3), a hormone known to increase heart rate. Compared to wild type, GPER mutants had reduced levels of T3 and estrogens, suggesting pituitary abnormalities. Exposure to exogenous T3, but not estradiol, rescued the reduced heart rate phenotype in gper mutant embryos, demonstrating that T3 acts downstream of GPER to regulate heart rate. Using genetic and mass spectrometry approaches, we find that GPER regulates maternal estrogen levels, which are required for normal embryonic heart rate. Our results demonstrate that estradiol plays a previously unappreciated role in the acute modulation of heart rate during zebrafish embryonic development and suggest that GPER regulates embryonic heart rate by altering maternal estrogen levels and embryonic T3 levels.

Estrogen hormones are important for the formation and function of the nervous, reproductive and cardiovascular systems. Here we report that acute exposure to estrogens increases heart rate, a previously unappreciated function of estrogens. Using zebrafish with mutations in genes that respond to estrogens, we found that heart rate is regulated not by the typical molecules that respond to estrogens–the nuclear estrogen receptors–but rather by a different molecule, the G protein-coupled estrogen receptor. We also show that estrogens increase heart rate by increasing levels of thyroid hormone. Our results reveal a new function for the G protein-coupled estrogen receptor and a new connection between estrogens and thyroid hormone. Environmental compounds that mimic estrogens can be harmful because they can influence gonad function. Our results suggest that endocrine disrupting compounds may also influence cardiac function.