Estetrol/GPER/SERPINB2 transduction signaling inhibits the motility of triple-negative breast cancer cells.

BACKGROUND: Estetrol (E4) is a natural estrogen produced by the fetal liver during pregnancy. Due to its favorable safety profile, E4 was recently approved as estrogenic component of a new combined oral contraceptive. E4 is a selective ligand of estrogen receptor (ER)α and ERß, but its binding to the G Protein-Coupled Estrogen Receptor (GPER) has not been described to date. Therefore, we aimed to explore E4 action in GPER-positive Triple-Negative Breast Cancer (TNBC) cells. METHODS: The potential interaction between E4 and GPER was investigated by molecular modeling and binding assays. The whole transcriptomic modulation triggered by E4 in TNBC cells via GPER was explored through high-throughput RNA sequencing analyses. Gene and protein expression evaluations as well as migration and invasion assays allowed us to explore the involvement of the GPER-mediated induction of the plasminogen activator inhibitor type 2 (SERPINB2) in the biological responses triggered by E4 in TNBC cells. Furthermore, bioinformatics analysis was aimed at recognizing the biological significance of SERPINB2 in ER-negative breast cancer patients. RESULTS: After the molecular characterization of the E4 binding capacity to GPER, RNA-seq analysis revealed that the plasminogen activator inhibitor type 2 (SERPINB2) is one of the most up-regulated genes by E4 in a GPER-dependent manner. Worthy, we demonstrated that the GPER-mediated increase of SERPINB2 is engaged in the anti-migratory and anti-invasive effects elicited by E4 in TNBC cells. In accordance with these findings, a correlation between SERPINB2 levels and a good clinical outcome was found in ER-negative breast cancer patients. CONCLUSIONS: Overall, our results provide new insights into the mechanisms through which E4 can halt migratory and invasive features of TNBC cells.

Low thrombin generation in postmenopausal women using estetrol.

OBJECTIVE: Estetrol (E4) represents a novel estrogen of interest to relieve vasomotor symptoms. E4 activates the nuclear estrogen receptor α (ERα) but antagonizes the estradiol ERα-dependent membrane-initiated steroid signaling pathway. The distinct pharmacological properties of E4 could explain its low impact on hemostasis. This study aimed to assess the effect of E4 on coagulation in postmenopausal women, using the thrombin generation assay (TGA). METHODS: Data were collected from a multicenter, randomized, placebo-controlled, dose-finding study in postmenopausal women (NCT02834312). Oral E4 (2.5 mg, n = 42; 5 mg, n = 29; 10 mg, n = 34; or 15 mg, n = 32) or placebo (n = 31) was administered daily for 12 weeks. Thrombograms and TGA parameters were extracted for each subject at baseline and after 12 weeks of treatment. RESULTS: After 12 weeks of treatment, all treatment groups showed a mean thrombogram (±95% confidence interval [CI] of the mean) within the reference ranges, that is, the 2.5th-97.5th percentile of all baseline thrombograms (n = 168), as well as for TGA parameters. CONCLUSIONS: The intake of E4 15 mg for 12 weeks led to significant but not clinically relevant changes compared to baseline as the mean values (±95% CI of the mean) remained within reference ranges, demonstrating a neutral profile of this estrogen on hemostasis.

Inhibitory effects of estetrol on the invasion and migration of immortalized human endometrial stromal cells.

Endometriosis, a common gynecological disorder characterized by the growth of endometrial gland and stroma outside the uterus, causes several symptoms such as dysmenorrhea, hypermenorrhea, and chronic abdominal pain. 17ß estradiol (E2) stimulates the growth of endometriotic lesions. Although estetrol (E4), produced by human fetal liver, is also a natural estrogen, it may have the opposite effects on endometriotic cells. We investigated different effects of E4 and E2 on the invasion and migration of immortalized human endometrial stromal cells (HESCs) and evaluated whether E4 affects the expression of Wiskott-Aldrich syndrome protein (WASP) family member 1 (WASF-1). We measured the invasion of HESCs by a Matrigel chamber assay. Cell migration was measured by wound healing assay and cell tracking analysis. The expression of WASF-1 was confirmed by independent real-time PCR analysis. Transfection of cells with siRNAs was carried out to knock down the expression of WASF-1 in HESCs. E4 significantly inhibited E2-induced invasion and migration of HESCs. WASF-1 was found to be a potential mediator based on metastasis PCR array. WASF-1 was upregulated by E2 and downregulated by E4. Knockdown of WASF-1 inhibited migration. Our results suggest that E4 may inhibit E2-induced growth of endometriotic lesions. Downregulation of WASF-1 is involved in the inhibitory effects of E4 on migration. The use of E4 combined with progestins as combined oral contraceptives may cause endometriotic lesions to regress in women with endometriosis.

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.

For contraceptive pills physicians can choose among different oestrogens, besides many progestins. Natural oestrogens have less metabolic impact vs EE, while EE and E4 seem to provide a better cycle control. Knowing the different oestrogen characteristics is crucial for adjusting pill prescription to women's needs and desires.

Correlation of sexual desire with sexual hormone binding globulin and free androgen index in women using combined contraceptives.

PURPOSE: To correlate the sexual desire levels with sexual hormone binding globulin and free androgen index in women taking different types of hormonal contraceptives (HCs) containing ethinylestradiol (EE), oestradiol valerate (E2V), 17ß-oestradiol (E2), or estetrol (E4), combined or in phasic formulation with different progestogens having antiandrogenic properties. METHODS: Three hundred and sixty-seven women (age range 18-46) participated in the study. SHBG and total testosterone (TT) were measured, and the Free Androgen Index (FAI) was calculated. The Female Sexual Function Index (FSFI) and the Female Sexual Distress Scale (FSDS) questionnaires were used to assess sexual function and distress, respectively. RESULTS: The highest SHBG values and the lowest FAIs were obtained of women on HCs containing EE than those of women on HCs containing E2V/17ß E2 or E4 (p < 0.001). Desire scores and FSFI total scores were lower in women on HCs with EE than in those using HCs containing E2V, 17ß E2, or E4 (p ≤ 0.001). The women who were on HCs containing EE reported FSDS levels higher than those containing all the other types of oestrogen. Finally, sexual desire and FSFI total scores had a negative correlation with the SHBG values and a positive correlation with FAI percentage (p ≤ 0.0001). CONCLUSIONS: A minority of women using HCs with EE might experience a decreased sexual desire. This was not observed in women on HCs containing E2V, 17 E2, or E4. To avoid HC discontinuation, due to sexual desire reduction, HCs having minor antiandrogenic effects could be taken into consideration.

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.

Comparison of Estetrol Exposure between Women and Mice to Model Preclinical Experiments and Anticipate Human Treatment.

Estetrol (E4) is a natural estrogen with promising therapeutic applications in humans. The European Medicines Agency and the Food and Drug Administration have approved the use of 15 mg E4/3 mg drospirenone for contraceptive indication. Phase III clinical trials with 15-20 mg E4 for the relief of climacteric complaints are currently running. Relevant data from preclinical animal models are needed to characterize the molecular mechanisms and the pharmacological effects of E4 and possibly to reveal new therapeutic applications and to anticipate potential adverse effects. Therefore, it is important to design experimental procedures in rodents that closely mimic or anticipate human E4 exposure. In this study, we compared the effects of E4 exposure after acute or chronic administration in women and mice. Women who received chronic E4 treatment per os at a dose of 15 mg once daily reached a steady state within 6 to 8 days, with a mean plasma concentration of 3.20 ng/mL. Importantly, with subcutaneous, intraperitoneal or oral administration of E4 in mice, a stable concentration over time that would mimic human pharmacokinetics could not be achieved. The use of osmotic minipumps continuously releasing E4 for several weeks provided an exposure profile mimicking chronic oral administration in women. Measurements of the circulating concentration of E4 in mice revealed that the mouse equivalent dose necessary to mimic human treatment does not fit with the allometric prediction. In conclusion, this study highlights the importance of precise definition of the most appropriate dose and route of administration to utilize when developing predictive preclinical animal models to mimic or anticipate specific human treatment.

Estetrol-Drospirenone combination oral contraceptive: a clinical study of contraceptive efficacy, bleeding pattern and safety in Europe and Russia.

OBJECTIVES: To assess the contraceptive efficacy, bleeding pattern and safety of a combined oral contraceptive containing estetrol (E4) 15 mg and drospirenone (DRSP) 3 mg. DESIGN: Multicenter, open-label, phase 3 trial. SETTING: Sixty-nine sites in Europe and Russia. POPULATION: Sexually active women aged 18-50 years with regular menstrual cycles and body mass index ≤35 kg/m2 . METHODS: E4/DRSP was administered in a 24 active/4 placebo regimen for up to 13 cycles. Visits were scheduled during Cycles 2, 4, 7 and 10 and after completing treatment during which adverse events (AEs) were collected. Participants recorded medication intake, vaginal bleeding/spotting, use of other contraceptive methods and sexual intercourse on a daily diary. MAIN OUTCOME MEASURES: Pearl Index (PI) for women 18-35 years (overall and method-failure), bleeding pattern and AEs. RESULTS: A total of 1553 women aged 18-50 years, including 1353 from 18 to 35 years old, received the study medication. PI was 0.47 pregnancies/100 woman-years (95% CI 0.15-1.11); method failure PI was 0.29 pregnancies/100 woman-years (95% CI 0.06-0.83). Scheduled bleeding/spotting occurred in 91.9-94.4% of women over Cycles 1 to 12 and lasted a median of 4-5 days per cycle. The percentage of women with unscheduled bleeding/spotting episodes decreased from 23.5% in Cycle 1 to <16% from Cycle 6 onwards. The most common AEs were headache (7.7%), metrorrhagia (5.5%), vaginal haemorrhage (4.8%) and acne (4.2%). One treatment-related serious AE was reported, a lower extremity venous thromboembolism. One-hundred and forty-one (9.1%) women discontinued study participation because of treatment-related adverse events. CONCLUSION: E4/DRSP provides effective contraception, a predictable bleeding pattern and a favourable safety profile. TWEETABLE ABSTRACT: A phase 3 trial with E4/DRSP shows high contraceptive efficacy, a predictable bleeding pattern and favourable safety profile.

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 15 mg/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, well-being, 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) 20 µg/DRSP 3 mg and EE 30 µg/levonorgestrel 150 µg. 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.

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.

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.

Estetrol prevents Western diet-induced obesity and atheroma independently of hepatic estrogen receptor α.

Estetrol (E4), a natural estrogen synthesized by the human fetal liver, is currently evaluated in phase III clinical studies as a new menopause hormone therapy. Indeed, E4 significantly improves vasomotor and genito-urinary menopausal symptoms and prevents bone demineralization. Compared with other estrogens, E4 was found to have limited effects on coagulation factors in the liver of women allowing to expect less thrombotic events. To fully delineate its clinical potential, the aim of this study was to assess the effect of E4 on metabolic disorders. Here, we studied the pathophysiological consequences of a Western diet (42% kcal fat, 0.2% cholesterol) in ovariectomized female mice under chronic E4 treatment. We showed that E4 reduces body weight gain and improves glucose tolerance in both C57Bl/6 and LDLR-/- mice. To evaluate the role of hepatic estrogen receptor (ER) α in the preventive effect of E4 against obesity and associated disorders such as atherosclerosis and steatosis, mice harboring a hepatocyte-specific ERα deletion (LERKO) were crossed with LDLR-/- mice. Our results demonstrated that, whereas liver ERα is dispensable for the E4 beneficial actions on obesity and atheroma, it is necessary to prevent steatosis in mice. Overall, these findings suggest that E4 could prevent metabolic, hepatic, and vascular disorders occurring at menopause, extending the potential medical interest of this natural estrogen as a new hormonal treatment.NEW & NOTEWORTHY Estetrol prevents obesity, steatosis, and atherosclerosis in mice fed a Western diet. Hepatic ERα is necessary for the prevention of steatosis, but not of obesity and atherosclerosis.

Estetrol and the possibilities of its clinical use

Combined hormonal contraceptive methods are one of the most commonly used methods of planned parenthood. They show high contraceptive effectiveness, reasonable cycle control and bring several non-contraceptive benefits. A limitation of the widespread use of combined hormonal contraception is the risk of cardiovascular complications in individuals with specific risk factors. The risk of cardiovascular complications is related to the used estrogen component. Currently, the most common use of estrogen in combined hormonal contraception is ethinyl estradiol and estradiol valerate. The good estrogenic part of combined oral contraceptives is estetrol, a hormone produced exclusively by the fetal liver. Estetrol exhibits a tissue-selective receptor activity. Unlike previously used estrogens, it does not negatively affect the production of liver proteins and blood clotting parameters. Estetrol is not a perspective for combined hormonal contraception only. It is also promising for treating and preventing osteoporosis, hormonal therapy of menopausal syndrome, and vulvovaginal atrophy syndrome.

Pharmacology and Molecular Mechanisms of Clinically Relevant Estrogen Estetrol and Estrogen Mimic BMI-135 for the Treatment of Endocrine-Resistant Breast Cancer.

Long-term estrogen deprivation (LTED) with tamoxifen (TAM) or aromatase inhibitors leads to endocrine-resistance, whereby physiologic levels of estrogen kill breast cancer (BC). Estrogen therapy is effective in treating patients with advanced BC after resistance to TAM and aromatase inhibitors develops. This therapeutic effect is attributed to estrogen-induced apoptosis via the estrogen receptor (ER). Estrogen therapy can have unpleasant gynecologic and nongynecologic adverse events. Here, we study estetrol (E4) and a model Selective Human ER Partial Agonist (ShERPA) BMI-135. Estetrol and ShERPA TTC-352 are being evaluated in clinical trials. These agents are proposed as safer estrogenic candidates compared with 17ß-estradiol (E2) for the treatment of endocrine-resistant BC. Cell viability assays, real-time polymerase chain reaction, luciferase reporter assays, chromatin immunoprecipitation, docking and molecular dynamics simulations, human unfolded protein response (UPR) RT2 PCR profiler arrays, live cell microscopic imaging and analysis, and annexin V staining assays were conducted. Our work was done in eight biologically different human BC cell lines and one human endometrial cancer cell line, and results were compared with full agonists estrone, E2, and estriol, a benchmark partial agonist triphenylethylene bisphenol (BPTPE), and antagonists 4-hydroxytamoxifen and endoxifen. Our study shows the pharmacology of E4 and BMI-135 as less-potent full-estrogen agonists as well as their molecular mechanisms of tumor regression in LTED BC through triggering a rapid UPR and apoptosis. Our work concludes that the use of a full agonist to treat BC is potentially superior to a partial agonist given BPTPE's delayed induction of UPR and apoptosis, with a higher probability of tumor clonal evolution and resistance. SIGNIFICANCE STATEMENT: Given the unpleasant gynecologic and nongynecologic adverse effects of estrogen treatment, the development of safer estrogens for endocrine-resistant breast cancer (BC) treatment and hormone replacement therapy remains a priority. The naturally occurring estrogen estetrol and Selective Human Estrogen-Receptor Partial Agonists are being evaluated in endocrine-resistant BC clinical trials. This work provides a comprehensive evaluation of their pharmacology in numerous endocrine-resistant BC models and an endometrial cancer model and their molecular mechanisms of tumor regression through the unfolded protein response and apoptosis.

Pharmacokinetics of the fetal estrogen estetrol in a multiple-rising-dose study in postmenopausal women.

OBJECTIVES: Estetrol (E4) is a natural fetal estrogen. In this open-label, multiple-rising-dose study, the pharmacokinetic effects of E4 in postmenopausal women were investigated as a secondary objective. METHODS: In total, 49 postmenopausal women were randomized to receive either 2 mg E4 or 2 mg estradiol valerate (E2V) for 28 days, or were (non-randomized) assigned to 10, 20, or 40 mg E4. The main outcome measures were: E4 plasma concentrations at trough, and on days 1 and 28; and E4 pharmacokinetic parameters AUC, Cmax and tmax on days 1 and 28. RESULTS: After oral administration, E4 showed a very fast absorption, followed by a multiphasic elimination with an initial rapid decline, gradually continuing with a slower elimination, suggesting a long terminal half-life. Steady state was reached within 2 weeks of dosing and pharmacokinetic results were generally proportional to the dose. Estetrol concentrations on day 28 were slightly higher compared to day 1, indicating some accumulation. CONCLUSION: The pharmacokinetic profile of estetrol is characterized by a very fast absorption phase, followed by an initial rapid decline, and a slow terminal elimination phase. Based on its kinetic properties, estetrol seems suitable for use as a once-daily oral drug.

Estetrol combined with drospirenone: an oral contraceptive with high acceptability, user satisfaction, well-being and favourable body weight control.

OBJECTIVES: This study evaluated acceptability, user satisfaction, body weight control and general well-being of estetrol (E4) combined with either drospirenone (DRSP) or levonorgestrel (LNG). METHODS: In this open-label, multi-centre, dose-finding, 6-cycle study, 396 healthy women of reproductive age were randomised into five treatment groups in a 24/4-day regimen: 15 mg or 20 mg E4 combined with either 3 mg DRSP or 150 µg LNG, and as reference estradiol valerate (E2V) combined with dienogest (DNG). Data on acceptability, user well-being, satisfaction and body weight were collected. RESULTS: The number of completers was the highest in the 15 mg E4/DRSP group (91.1%), and the lowest for 20 mg E4/LNG (70.1%). The largest proportion of treatment satisfaction was reported for 15 mg E4/DRSP (73.1%), and the lowest for 15 mg E4/LNG (50.6%). The number of women willing to continue with the assigned study treatment was the highest in the 15 mg E4/DRSP group (82.1%) and the lowest for 20 mg E4/LNG (58.3%). Well-being with E4/DRSP combinations was statistically significantly better than with E4/LNG combinations: OR (95% CI) 2.00 (1.13; 3.53) and 1.93 (1.06; 3.56) for 15 and 20 mg E4, respectively, and comparable to E2V/DNG. Proportion of women with a 2 kg or more weight loss after 3 and 6 cycles was the highest in the 15 mg E4/DRSP group (30.7 and 36.7%, respectively). CONCLUSIONS: The present study shows that 15 mg estetrol combined with 3 mg DRSP is associated with a high-user acceptability and satisfaction, and with a favourable body weight control.

Inhibition of ovulation by administration of estetrol in combination with drospirenone or levonorgestrel: Results of a phase II dose-finding pilot study.

OBJECTIVES: The aim of the study was to evaluate the efficacy of different dosages of estetrol (E4) combined with one of two progestins in suppressing the pituitary-ovarian axis and ovulation in healthy premenopausal women. METHODS: This was an open, parallel, phase II, dose-finding, pilot study performed in healthy women aged 18 to 35 years with a documented ovulatory cycle before treatment. For three consecutive cycles in a 24/4-day regimen, participants received 5 mg or 10 mg E4/3 mg drospirenone (DRSP); 5 mg, 10 mg or 20 mg E4/150 µg levonorgestrel; or 20 µg ethinylestradiol (EE)/3 mg DRSP as comparator. Pituitary-ovarian axis activity and the occurrence of ovulation were evaluated by monitoring follicular size, serum levels of follicle-stimulating hormone, luteinising hormone, estradiol and progesterone during treatment cycles 1 and 3. Endometrial thickness was evaluated throughout the trial, and the return of ovulation was evaluated after the last intake of medication. RESULTS: A total of 109 women were included in the trial. No ovulation occurred in any treatment group. Ovarian activity inhibition seemed proportional to the E4 dosage: the highest suppression was observed in the 20 mg E4 group and was very similar to that observed with EE/DRSP. Endometrial thickness was suppressed to the same extent in all groups. Post-treatment ovulation occurred in all participants between 17 and 21 days after the last active treatment. The study combinations were well tolerated and safe. CONCLUSIONS: Combined with a progestin, E4 adequately suppresses ovarian activity, particularly when given at a dosage above 10 mg/day.

Oestetrol stimulates proliferation and oestrogen receptor expression in breast cancer cell lines: comparison of four oestrogens.

OBJECTIVES: Oestetrol (15-alpha-hydroxyoestriol, E4) is an endogenous oestradiol metabolite mainly produced at high concentrations in the fetal liver. In earlier studies E4 was investigated for its use as marker for pregnancies at risk, especially with vascular problems. Some current investigations suggest that the use of E4 in hormone therapy or contraception may have advantages in terms of breast cancer risk when compared to other oestrogens. METHODS: Proliferation of two oestrogen receptor-positive breast cancer cell lines (ZR 75-1 and HCC 1500) was investigated after incubation with oestrone (E1), oestradiol (E2), oestriol (E3), and oestetrol (E4). Receptor expression of oestrogen receptor-alpha (ERα) and -beta (ERß) was determined by Western-Blot. RESULTS: All four oestrogens elicited a significant proliferative stimulation at concentrations of 10(-10) und 10(-9) M as compared to controls. Oestrone displayed a significantly weaker effect than E2. Oestetrol was significantly less effective than E2 at the lower concentration. Expression of ERα and ERß was significantly upregulated by all oestrogens tested, without differences between the latter. CONCLUSIONS: Our results indicate a slightly lower proliferative effect of E4, but only at low concentrations. However, no difference was found regarding receptor expression. Breast cancer risk associated with use of oestetrol should be tested in clinical trials.

Unique effects on hepatic function, lipid metabolism, bone and growth endocrine parameters of estetrol in combined oral contraceptives.

OBJECTIVES: Estetrol (E4) is a natural estrogen produced by the human fetal liver. In combination with drospirenone (DRSP) or levonorgestrel (LNG), E4 blocks ovulation and has less effect on haemostatic biomarkers in comparison with ethinylestradiol (EE) combined with DRSP. This study evaluates the impact of several doses of E4/DRSP and E4/LNG on safety parameters such as liver function, lipid metabolism, bone markers and growth endocrine parameters. METHODS: This was a dose-finding, single-centre, controlled study performed in healthy women aged 18 to 35 years with a documented pretreatment ovulatory cycle. Participants received 5 mg or 10 mg E4/3 mg DRSP; 5 mg, 10 mg or 20 mg E4/150 µg LNG; or 20 µg EE/3 mg DRSP as a comparator for three consecutive cycles in a 24/4-day regimen. Changes from baseline to end of treatment in liver parameters, lipid metabolism, bone markers and growth endocrinology were evaluated. RESULTS: A total of 109 women were included in the study. Carrier proteins were minimally affected in the E4/DRSP and E4/LNG groups, in comparison with the EE/DRSP group, where a significant increase in sex hormone-binding globulin was observed. Similarly, minor effects on lipoproteins were observed in the E4 groups, and the effects on triglycerides elicited by the E4 groups were significantly lower than those in the EE/DRSP group. No imbalances in bone markers were observed in any groups. No alterations in insulin-like growth factor were observed in the E4 groups. CONCLUSIONS: E4-containing combinations have a limited effect on liver function, lipid metabolism, and bone and growth endocrine parameters.

Antiestrogenic effects of the fetal estrogen estetrol in women with estrogen-receptor positive early breast cancer.

Estetrol (E4) is a fetal estrogen with estrogenic effects on reproductive organs and bone in preclinical models and in postmenopausal women. However, E4 exerts antiestrogenic effects on breast cancer (BC) cell growth in vitro and in vivo. We have investigated the effect of 14 days preoperative treatment with 20mg E4 per day on tumor proliferation markers, sex steroid receptor expression and endocrine parameters in a prospective, randomized, placebo-controlled, preoperative window trial in 30 pre- and post-menopausal women with estrogen-receptor positive early BC. E4 had a significant pro-apoptotic effect on tumor tissue, whereas Ki67 expression remained unchanged in both pre- and post-menopausal women. E4 increased sex-hormone-binding globulin significantly thereby reducing the concentrations of bioavailable estradiol. Follicle-stimulating hormone levels decreased in postmenopausal women only and luteinizing hormone levels remained unchanged. Systemic insulin growth factor-1 levels decreased significantly. Intratumoral epithelial ERα expression decreased significantly and a trend was found towards an increased expression of ERß. This clinical data support the preclinical findings that E4 has antiestrogenic effects on BC cells, whereas earlier studies have shown that E4 has estrogenic effects on reproductive tissues and bone. Further clinical studies seem acceptable and are needed to confirm the safety and efficacy of E4 for the breast in hormone replacement therapy, including hormone replacement therapy in women who have or have had BC, especially in those BC patients treated with aromatase inhibitors and suffering from serious complaints due to estrogen deficiency.