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

Estetrol: From Preclinical to Clinical Pharmacology and Advances in the Understanding of the Molecular Mechanism of Action

Estetrol (E4) is the most recently described natural estrogen. It is produced by the human fetal liver during pregnancy and its physiological function remains unclear. E4 is the estrogenic component of a recently approved combined oral contraceptive. It is also in development for use as menopausal hormone therapy. In the context of these developments, the pharmacological activity of E4, alone or in combination with a progestin, has been extensively characterized in preclinical models as well as in clinical studies in women of reproductive age and postmenopausal women. Despite the clinical benefits, the use of oral estrogens for contraception or menopause is also associated with unwanted effects, such as an increased risk of breast cancer and thromboembolic events, due to their impact on non-target tissues. Preclinical and clinical data for E4 point to a tissue-specific activity and a more selective pharmacological profile compared with other estrogens, including a low impact on the liver and hemostasis balance. This review summarizes the characterization of the pharmacological properties of E4 as well as recent advances made in the understanding of the molecular mechanisms of action driving its activity. How the unique mode of action and the different metabolism of E4 might support its favorable benefit-risk ratio is also discussed.

Testosterone suppression combined with high dose estrogen as potential treatment of SARS-CoV-2. A mini review

Compared to females, males experience severe acute respiratory syndrome due to COVID-19 (SARS-CoV-2) more often, and also die more frequently from COVID-19. Testosterone has inhibitory and estrogens have favorable effects on the immune system. Both ACE2 and TMPRSS2 are specific host-cellular proteins stimulating viral entry in cells and SARS-CoV-2. Both proteins can be suppressed by inhibition of testosterone levels and by stimulation of estrogen levels. Therefore, both androgen-deprivation therapy (ADT) and estrogen therapy (ET) may decrease COVID-19 virus cell entry. Literature was searched for evidence of COVID-19 treatment benefits with estrogens, progesterone, androgen deprivation, and anti-androgens. Data supporting the effect of ADT on SARS-CoV-2 are sparse and inconsistent. The benefit of anti-androgen therapy is inconsistent. Data on the effect of ET were not found. Indirect estrogen data related to menopausal hormone therapy and hormonal contraception are favorable. In a small study, progesterone had some beneficial effects. The combination of ADT and ET (ADET) has never been studied as a treatment option for SARS-CoV-2. Based on the mode of action of the combination, it is hypothesized that ADET may be an effective and safe treatment of SARS-CoV-2, to be confirmed in a clinical trial.

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.

Effects of oestradiol treatment on hot flushes in men undergoing androgen deprivation therapy for prostate cancer: a randomised placebo-controlled trial

OBJECTIVE

Most men undergoing androgen deprivation therapy (ADT) for prostate cancer experience hot flushes. Current treatments have low or limited evidence of efficacy. It is likely that oestradiol depletion is the mediator of these hot flushes, and transdermal oestradiol might be an effective treatment.

DESIGN

This is a 6-month randomised, placebo-controlled trial with the hypothesis that oestradiol would reduce hot flush frequency and intensity and improve quality of life (QoL).

METHODS

Seventy-eight participants receiving ADT were randomised to 0.9 mg of 0.1% oestradiol gel per day or matched placebo. Hot flush frequency and severity were assessed by 7-day diary at baseline, month 1, month 3, and month 6. QoL was assessed by validated questionnaire.

RESULTS

Oestradiol reduced daily hot flush frequency, with a mean adjusted difference (MAD) of -1.6 hot flushes per day (95% CI: -2.7 to -0.5; P = 0.04). The effect on weekly hot flush score was non-significant, with a MAD -19.6 (95% CI: -35.5 to -3.8; P = 0.11). On per protocol analysis, E2 significantly reduced daily hot flush frequency, with a MAD of -2.2 hot flushes per day (95% CI: -3.2 to -1.1; P = 0.001), and weekly hot flush score, with a MAD of -27.0 (-44.7 to -9.3; P = 0.02). Oestradiol had no significant effect on QoL.

CONCLUSION

We confirmed our hypothesis of a clinical effect of assignment to oestradiol to reduce hot flush frequency in men with castrate testosterone due to ADT. Transdermal oestradiol could be considered for men with burdensome hot flushes in whom other treatments have failed as long as the risk of breast effects and fat gain are considered.

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.