Progesterone receptor modulators and the endometrium: changes and consequences

Cyclical endometrial repair and regeneration: Molecular mechanisms, diseases, and therapeutic interventions

The endometrium is a unique human tissue with an extraordinary ability to undergo a hormone-regulated cycle encompassing shedding, bleeding, scarless repair, and regeneration throughout the female reproductive cycle. The cyclical repair and regeneration of the endometrium manifest as changes in endometrial epithelialization, glandular regeneration, and vascularization. The mechanisms encompass inflammation, coagulation, and fibrinolytic system balance. However, specific conditions such as endometriosis or TCRA treatment can disrupt the process of cyclical endometrial repair and regeneration. There is uncertainty about traditional clinical treatments' efficacy and side effects, and finding new therapeutic interventions is essential. Researchers have made substantial progress in the perspective of regenerative medicine toward maintaining cyclical endometrial repair and regeneration in recent years. Such progress encompasses the integration of biomaterials, tissue-engineered scaffolds, stem cell therapies, and 3D printing. This review analyzes the mechanisms, diseases, and interventions associated with cyclical endometrial repair and regeneration. The review discusses the advantages and disadvantages of the regenerative interventions currently employed in clinical practice. Additionally, it highlights the significant advantages of regenerative medicine in this domain. Finally, we review stem cells and biologics among the available interventions in regenerative medicine, providing insights into future therapeutic strategies.

Next step in the development of mesoprogestins: the preclinical profile of EC313

Introduction

The pharmacological target for progesterone, different progestins, and Selective Progesterone Receptor Modulators (SPRMs) is the nuclear progesterone receptor (PR). EC313 is a new member of a subgroup of SPRMs, mesoprogestins, which combine especially PR- agonistic and PR-antagonistic activities in one molecule.

Methods

The suitable in vivo-model for the differentiation of SPRMs from the subgroup of mesoprogestins is the estrogen-primed juvenile rabbit endometrium assay (McPhail Assay). Remarkably, in contrast to other well-known SPRMs with no agonistic effects in this test, EC313 shows clear partial PR-agonistic effects that are higher than that of the well-known mesoprogestin Asoprisnil which already demonstrated remarkable clinical effectiveness for the treatment of uterine fibroids and endometriosis. The findings from the guinea pig studies presented here can be the impetus for further preclinical development of EC313. This model shows the same features for the termination of pregnancy by antiprogestins such as Mifepristone and Ulipristal acetate (UPA) in humans. Moreover, it is possible to distinguish between progestational and anti-progestational activities in the same experiment.

Results

The EC313 treatment reveals PR dominance in the genital tract and inhibits unopposed estrogenic effects. In very high doses (30.0 mg/animal/day subcutaneously (s.c.)) given twice on pregnancy days 43 and 44, no premature labor was induced (in contrast to UPA, dosed at 10.0 and 30. mg/animal/day s.c.). The anti-ovulatory activity of EC313 exceeds that of Ulipristal acetate or Mifepristone. EC313 binds to the steroid receptors in vitro with a similar affinity as the natural ligand progesterone. At the glucocorticoid receptor (GR) EC313 acts as a weak inhibitor. Minor activities at the human androgen receptor (AR) and mineralocorticoid receptor (MR) are considered negligible. No binding to the estradiol receptor was detected. In contrast to some in vitro-receptor findings, estrogenic, anti-estrogenic, androgenic, anti-androgenic, glucocorticoid, and anti-glucocorticoid actions were absent in vivo. The tissue selectivity of EC313 was demonstrated previously by reducing the growth and proliferation of uterine fibroids in animal models (lowest effective dosage 0.1 mg/kg/day s.c.).. As shown in this article, the anti-fibroid activity of EC313 was confirmed with a 10 times lower dosage (0.01 mg/kg/day s.c.). It was also shown that EC313 reduces the growth of endometriotic lesions in a human xenograft immune-deficient (NOD-SCID) mice model with a comparatively very low dosage range. In the aforementioned EC313 activity model, UPA was tested as the reference compound, the clinical effectiveness of which has already been demonstrated.

Discussion

For an explanation of these findings, the possibility is discussed that the mixed agonistic/antagonistic feature of EC313 is tissue target-specific based on its super-additive synergism characteristic for active bifunctional agents. In conclusion, the specific pharmacodynamic profile of this compound opens the possibility for the development of a drug with a distinct pharmaco-endocrinological profile against uterine fibroids, endometriosis, and other PR-dependent gynecological diseases.

Long-term use of ultra-low-dose mifepristone for uterine leiomyoma control and safety discussion: A case report

RATIONALE

In recent years, many clinical trials have used low-dose mifepristone to control uterine fibroids, some of which have achieved good results. However, according to the classic concept, long-term use of mifepristone could induce malignant transformation of the endometrium, and the effect of ultra-low-dose of mifepristone on uterine fibroids is still uncertain. Researchers are short on cases of uterine fibroids treated with mifepristone for long periods (more than a year).

PATIENT CONCERNS

A 47-year-old woman went to the hospital because of anemia.

DIAGNOSES

The patient was diagnosed with uterine leiomyoma.

INTERVENTIONS

The patient refused the suggestion of surgery, she was continuously treated with an ultra-low-dose (12.5 mg per 5 days) of mifepristone monotherapy for 4 years.

OUTCOMES

The uterine leiomyoma was stable, anemia and other symptoms disappeared, and the menstrual cycle, liver and kidney function, and tumor markers were normal.

LESSONS

Judging from our case, long-term, ultra-low-dose mifepristone for uterine fibroids treatment was safe and more effective than conventional therapy.

Ultrasonographic appearance of the endometrium after saline infusion in women presenting with PRM-associated endometrial changes, due to the use of ulipristal acetate

Ulipristal acetate (UPA), used for the treatment in women with symptomatic fibroids, is associated with endometrial changes visualised on ultrasound as thickening up to more than 16 mm in approximately 10% of the patients. Is saline infusion sonography (SIS) a good alternative for more invasive techniques, to evaluate the presence of intrauterine pathology? Ten patients, presenting with UPA associated endometrial changes at their follow up ultra-sonographic evaluation, were included. Our study demonstrated that SIS is feasible and painless in patients presenting with UPA associated endometrial changes. The thickened endometrium appears to divide at the midline, making it possible to study both layers separately and exclude any suspected intrauterine pathology. Our findings suggest that SIS may be a first choice, non-invasive, painless technique to provide a proper visualisation to rule out intrauterine pathology when UPA associated endometrial changes are diagnosed after fibroid treatment. This is especially of clinical interest in front of assisted reproductive technology treatment. Invasive techniques can be withheld for patients in whom SIS examination is not contributive.Impact StatementWhat is already known on this subject? Reversible endometrial changes after ulipristal acetate (UPA) treatment in patients with symptomatic fibroids have been described. In patients who receive UPA, especially if planned to undergo ART, assessment of potential endometrial pathology is important as such interfere with proper implantation after ART. Consequently, clinicians may consider ruling out intrauterine pathology by invasive examinations such as biopsy or hysteroscopy after visualisation of the thickened endometrium.What do the results of this study add? Saline infusion sonography (SIS) was feasible and painless in patients presenting with UPA associated endometrial changes.What are the implications of these findings for clinical practice and/or further research? SIS may be a first choice, non-invasive, painless technique to provide a proper visualisation to rule out intrauterine pathology when UPA associated endometrial changes are diagnosed after fibroid treatment. This is especially of clinical interest in front of assisted reproductive technology treatment. Invasive techniques can be withheld for patients in whom SIS examination is not contributive in excluding intrauterine pathology.

Clinical Update on Uses for Mifepristone in Obstetrics and Gynecology

IMPORTANCE

Mifepristone (RU-486) is a selective progesterone receptor modulator that has antagonist properties on the uterus and cervix. Mifepristone is an effective abortifacient, prompting limitations on its use in many countries. Mifepristone has many uses outside of induced abortion, but these are less well known and underutilized by clinicians because of challenges in accessing and prescribing this medication.

OBJECTIVES

To provide clinicians with a history of the development of mifepristone and mechanism of action and safety profile, as well as detail current research on uses of mifepristone in both obstetrics and gynecology.

EVIDENCE ACQUISITION

A PubMed search of mifepristone and gynecologic and obstetric conditions was conducted between January 2018 and December 2021. Other resources were also searched, including guidelines from the American College of Obstetricians and Gynecologists and the Society of Family Planning.

RESULTS

Mifepristone is approved by the Food and Drug Administration for first-trimester medication abortion but has other off-label uses in both obstetrics and gynecology. Obstetric uses that have been investigated include management of early pregnancy loss, intrauterine fetal demise, treatment of ectopic pregnancy, and labor induction. Gynecologic uses that have been investigated include contraception, treatment of abnormal uterine bleeding, and as an adjunct in treatment of gynecologic cancers.

CONCLUSIONS AND RELEVANCE

Mifepristone is a safe and effective medication both for its approved use in first-trimester medication abortion and other off-label uses. Because of its primary use as an abortifacient, mifepristone is underutilized by clinicians. Providers should consider mifepristone for other indications as clinically appropriate.

Histomorphometric analysis of goat uterine tissue on in vitro exposure with ovarian hormones and mifepristone

Uterus, the largest reproductive tract organ in female mammals, is the site of implantation of fertilised egg and foetus development. Uterus is a dynamic reproductive organ; its morphology alters with reproductive phase and steroidal cues. The aim of the present study was to assess the effects of progesterone (P4), estrogen (E2) and antiprogestogen i.e., mifepristone on goat’s uterine histoarchitecture in in vitro short term culture. Uterine tissue slices were cultured in the presence of E2, P4 and mifepristone at the dose of 10–9 M, 10–7 M and 10–6 M respectively for 24 hours. Uter-ine morphology of E2- and P4-treated groups did not reveal marked changes from that of control group. Mifepristone treatment caused conspicuous changes in uterine histoarchitecture, led to congested endometrium, regressed uterine glands and constricted blood vessels. The changes ob-served in morphometry after E2 and P4 exposure included increased uterine gland diameter (47.00 and 45.95 µm respectively) and glandular epithelial cell height (18.37 and 17.43 µm respectively) while the mifepristone treatment resulted in significant reduction of gland diameter (34.95 µm) as well as epithelium height (14.25 µm) as compared to those in control group (39.9 and 15.56 µm respectively). These morphometrical changes revealed prominent regressive changes in anti-progestin treated group while E2 and P4 showed prolific effects in in vitro culture. Thus it is envis-aged that E2 and P4 induced characteristic progressive changes in the histologic structure especially in endometrial glands of the goat uterus while anti-steroidogenic formulation i.e. mifepristone severely reduced the normal histoarchitecture of the uterus which is a prerequisite for implanta-tion.

Physiology of the Endometrium and Regulation of Menstruation

The physiological functions of the uterine endometrium (uterine lining) are preparation for implantation, maintenance of pregnancy if implantation occurs, and menstruation in the absence of pregnancy. The endometrium thus plays a pivotal role in reproduction and continuation of our species. Menstruation is a steroid-regulated event, and there are alternatives for a progesterone-primed endometrium, i.e., pregnancy or menstruation. Progesterone withdrawal is the trigger for menstruation. The menstruating endometrium is a physiological example of an injured or “wounded” surface that is required to rapidly repair each month. The physiological events of menstruation and endometrial repair provide an accessible in vivo human model of inflammation and tissue repair. Progress in our understanding of endometrial pathophysiology has been facilitated by modern cellular and molecular discovery tools, along with animal models of simulated menses. Abnormal uterine bleeding (AUB), including heavy menstrual bleeding (HMB), imposes a massive burden on society, affecting one in four women of reproductive age. Understanding structural and nonstructural causes underpinning AUB is essential to optimize and provide precision in patient management. This is facilitated by careful classification of causes of bleeding. We highlight the crucial need for understanding mechanisms underpinning menstruation and its aberrations. The endometrium is a prime target tissue for selective progesterone receptor modulators (SPRMs). This class of compounds has therapeutic potential for the clinical unmet need of HMB. SPRMs reduce menstrual bleeding by mechanisms still largely unknown. Human menstruation remains a taboo topic, and many questions concerning endometrial physiology that pertain to menstrual bleeding are yet to be answered.

Ulipristal acetate for Japanese women with symptomatic uterine fibroids: A double-blind, randomized, phase II dose-finding study

PURPOSE

A multicenter, randomized, double-blind, placebo-controlled trial was conducted to evaluate the efficacy, safety, and appropriate dose of ulipristal acetate (UPA) in Japanese women with symptomatic uterine fibroids (UFs).

METHODS

A total of 121 premenopausal women with UFs were enrolled to receive either placebo, UPA-2.5 mg, UPA-5 mg, UPA-10 mg, or leuprorelin acetate (LEU), a reference drug, for 12 weeks. The primary end point was the rate of patients having achieved amenorrhea for 35 days at Week 12.

RESULTS

The rates for amenorrhea were 4.5%, 60.0%, 72.7%, 88.0%, and 76.2% in the placebo, UPA-2.5 mg, UPA-5 mg, UPA-10 mg, and LEU groups, respectively. The median times to amenorrhea were 20.0, 5.0, 5.0, and 23.0 days for treatment with UPA-2.5 mg, UPA-5 mg, UPA-10 mg, and LEU, respectively. A significant dose-response of UPA for the rate of amenorrhea was observed. The overall incidence rates of adverse events were 45.8% in the placebo group, 56.5%-80.0% in the UPA groups, and 100.0% in the LEU group. There were no notable safety issues with UPA.

CONCLUSIONS

Ulipristal acetate was effective and well tolerated in Japanese women with UFs. The recommended dose of UPA is considered to be 10 mg.

Functional genomic analysis of the human receptive endometrium transcriptome upon administration of mifepristone at the time of follicle rupture

The aim of this study was to analyze the effects of progesterone withdrawal on gene transcription in receptive endometrium by the administration of a single dose of 50 mg of the anti-progesterone receptor mifepristone (MFP) at the time of follicle rupture (FR). Six volunteer ovulatory women were studied, taking endometrial biopsies of three control and three MFP-treated women on days LH+2 (C-LH+2) and LH+7 (T-MFP), respectively. The biopsies were prepared for RNA isolation or histological and immunohistochemistry studies. The genomic data from 14 women (C-LH+7) were included as a historical control. The functional genomic analysis of the differentially expressed genes showed that MFP interfered negatively with the bio-functions decidualization of uterus and implantation of blastocyst and embryo. The results of this study confirm but also give new information on how MFP affects endometrial gene expression when administered at the time of FR and the dose used in emergency contraception.

Sonic hedgehog protects endometrial hyperplasial cells against oxidative stress via suppressing mitochondrial fission protein dynamin-like GTPase (Drp1)

Hh/Gli1 cascade as well as Gsk3β-Gli1 crosstalk play crucial role in estrogen-dependent progression of endometrial hyperplasia (EH). However, the underlying mechanisms involved in progression of disease still remain unclear. In the present study, we explored the role of Hh signaling in protection of endometrial hyperplasial cells against oxidative stress and the underlying mechanism involved therein. EH cells were found to be more resistant towards H₂O₂-induced oxidative stress (IC₅₀: ~ 3×) as compared with normal endometrial cells. Estrogen (E2) pre-treatment followed by cytotoxic dose of H₂O_2, almost rescued the EH cells from apoptosis and caused the increased expression of downstream Shh signaling molecules i.e., Smo, Ptch and Gli1. Whereas pretreatment with cyclopamine was not able to curtail H₂O₂-induced effects indicating that estrogen protects these cells via activation of Shh pathway. Further, H₂O₂-induced ROS and lipid peroxidation alongwith decreased activities of antioxidant enzymes glutathione peroxidase and superoxide dismutase were found to be reversed in EH cells pre-exposed to E2 or rShh. The rShh suppressed H₂O₂-induced cell death and caused attenuation of mitochondrial apoptotic mediators and prevented disruption in mitochondrial morphology and mitochondrial membrane potential in EH cells. The functional blockage of signaling by Shh siRNA or Gli1siRNA led to significantly increased expression of mitochondrial fission protein dynamin-like GTPase (Drp1). The H₂O₂-treated EH cells showed diminished Gli1 and increased Drp1 expression, concurrent with reduced p-Drp1-(serine637). Whereas rShh pre-treated EH cells presented normal mitochondrial dynamics with dense, long networks of mitochondria alongwith nuclear accumulation of Gli1 and the decreased expression of Drp1. Overall, our results implicated that Shh signaling modulates antioxidant defense system and stabilizes mitochondrial dynamics by suppressing Drp1 protein which maintains survival of EH cells against oxidative stress.

The past, present, and future of selective progesterone receptor modulators in the management of uterine fibroids

Uterine fibroids are common in women of reproductive age and can have a significant impact on quality of life and fertility. Although a number of international obstetrics/gynecology societies have issued evidence-based clinical practice guidelines for the management of symptomatic uterine fibroids, many of these guidelines do not yet reflect the most recent clinical evidence and approved indication for one of the key medical management options: the selective progesterone receptor modulator class. This article aims to share the clinical experience gained with selective progesterone receptor modulators in Europe and Canada by reviewing the historical development of selective progesterone receptor modulators, current best practices for selective progesterone receptor modulator use based on available data, and potential future uses for selective progesterone receptor modulators in uterine fibroids and other gynecologic conditions.

A Comprehensive Review of the Pharmacologic Management of Uterine Leiomyoma

Uterine leiomyomata are the most common benign tumors of the gynecologic tract impacting up to 80% of women by 50 years of age. It is well established that these tumors are the leading cause for hysterectomy with an estimated total financial burden greater than $30 billion per year in the United States. However, for the woman who desires future fertility or is a poor surgical candidate, definitive management with hysterectomy is not an optimal management plan. Typical gynecologic symptoms of leiomyoma include infertility, abnormal uterine bleeding (AUB)/heavy menstrual bleeding (HMB) and/or intermenstrual bleeding (IMB) with resulting iron-deficiency anemia, pelvic pressure and pain, urinary incontinence, and dysmenorrhea. The morbidity caused by these tumors is directly attributable to increases in tumor burden. Interestingly, leiomyoma cells within a tumor do not rapidly proliferate, but rather the increase in tumor size is secondary to production of an excessive, stable, and aberrant extracellular matrix (ECM) made of disorganized collagens and proteoglycans. As a result, medical management should induce leiomyoma cells toward dissolution of the extracellular matrix, as well as halting or inhibiting cellular proliferation. Herein, we review the current literature regarding the medical management of uterine leiomyoma.

Current management of myomas: the place of medical therapy with the advent of selective progesterone receptor modulators

PURPOSE OF REVIEW

To review the current management of myomas with the advent of selective progesterone receptor modulators.

RECENT FINDINGS

Selective progesterone receptor modulators have proved effective and recent publications on the use of ulipristal acetate (UPA) have analyzed the performance of long-term intermittent utilization of 10 mg UPA given in repeated courses of 3 months. This long-term intermittent therapy maximizes the efficacy of UPA. Indeed, control of bleeding is achieved sooner after each course. With each subsequent course, a statistically greater number of patients show a fibroid volume reduction of more than 50%.

SUMMARY

The choice of therapy is influenced by different factors, such as the severity of symptoms, tumor characteristics, age, and wish to preserve the uterus (and fertility). Use of UPA will undoubtedly modify the surgical approach.

Ulipristal acetate for use in moderate to severe symptoms of uterine fibroids

Although it has been known for a long time that uterine fibroids respond to changes in sex steroid concentrations, it is the availability of selective progesterone receptor modulators such as ulipristal acetete that has provided the gynecologist with a novel option for medical management of uterine fibroids. Ulipristal acetate is presently licensed in Europe for use in women with symptomatic fibroids up to 3 months prior to surgery and has demonstrated good clinical efficacy and safety for this indication. Future trials will define the long-term safety of this drug and its role in medical management of uterine fibroids.

Therapeutic options for management of endometrial hyperplasia

Endometrial hyperplasia (EH) comprises a spectrum of changes in the endometrium ranging from a slightly disordered pattern that exaggerates the alterations seen in the late proliferative phase of the menstrual cycle to irregular, hyperchromatic lesions that are similar to endometrioid adenocarcinoma. Generally, EH is caused by continuous exposure of estrogen unopposed by progesterone, polycystic ovary syndrome, tamoxifen, or hormone replacement therapy. Since it can progress, or often occur coincidentally with endometrial carcinoma, EH is of clinical importance, and the reversion of hyperplasia to normal endometrium represents the key conservative treatment for prevention of the development of adenocarcinoma. Presently, cyclic progestin or hysterectomy constitutes the major treatment option for EH without or with atypia, respectively. However, clinical trials of hormonal therapies and definitive standard treatments remain to be established for the management of EH. Moreover, therapeutic options for EH patients who wish to preserve fertility are challenging and require nonsurgical management. Therefore, future studies should focus on evaluation of new treatment strategies and novel compounds that could simultaneously target pathways involved in the pathogenesis of estradiol-induced EH. Novel therapeutic agents precisely targeting the inhibition of estrogen receptor, growth factor receptors, and signal transduction pathways are likely to constitute an optimal approach for treatment of EH.

Ovarian steroids, stem cells and uterine leiomyoma: therapeutic implications

BACKGROUND

Uterine leiomyoma is the most common benign tumor in women and is thought to arise from the clonal expansion of a single myometrial smooth muscle cell transformed by a cellular insult. Leiomyomas cause a variety of symptoms, including abnormal uterine bleeding, pelvic pain, bladder or bowel dysfunction, and recurrent pregnancy loss, and are the most common indication for hysterectomy in the USA. A slow rate of cell proliferation, combined with the production of copious amounts of extracellular matrix, accounts for tumor expansion. A common salient feature of leiomyomas is their responsiveness to steroid hormones, thus providing an opportunity for intervention.

METHODS

A comprehensive search of PUBMED was conducted to identify peer-reviewed literature published since 1980 pertinent to the roles of steroid hormones and somatic stem cells in leiomyoma, including literature on therapeutics that target steroid hormone action in leiomyoma. Reviewed articles were restricted to English language only. Studies in both animals and humans were reviewed for the manuscript.

RESULTS

Estrogen stimulates the growth of leiomyomas, which are exposed to this hormone not only through ovarian steroidogenesis, but also through local conversion of androgens by aromatase within the tumors themselves. The primary action of estrogen, together with its receptor estrogen receptor α (ERα), is likely mediated via induction of progesterone receptor (PR) expression, thereby allowing leiomyoma responsiveness to progesterone. Progesterone has been shown to stimulate the growth of leiomyoma through a set of key genes that regulate both apoptosis and proliferation. Given these findings, aromatase inhibitors and antiprogestins have been developed for the treatment of leiomyoma, but neither treatment results in complete regression of leiomyoma, and tumors recur after treatment is stopped. Recently, distinct cell populations were discovered in leiomyomas; a small population showed stem-progenitor cell properties, and was found to be essential for ovarian steroid-dependent growth of leiomyomas. Interestingly, these stem-progenitor cells were deficient in ERα and PR and instead relied on the strikingly higher levels of these receptors in surrounding differentiated cells to mediate estrogen and progesterone action via paracrine signaling.

CONCLUSIONS

It has been well established that estrogen and progesterone are involved in the proliferation and maintenance of uterine leiomyoma, and the majority of medical treatments currently available for leiomyoma work by inhibiting steroid hormone production or action. A pitfall of these therapeutics is that they decrease leiomyoma size, but do not completely eradicate them, and tumors tend to regrow once treatment is stopped. The recent discovery of stem cells and their paracrine interactions with more differentiated cell populations within leiomyoma has the potential to provide the missing link between developing therapeutics that temper leiomyoma growth and those that eradicate them.

Medical treatments for endometriosis-associated pelvic pain

The main sequelae of endometriosis are represented by infertility and chronic pelvic pain. Chronic pelvic pain causes disability and distress with a very high economic impact. In the last decades, an impressive amount of pharmacological agents have been tested for the treatment of endometriosis-associated pelvic pain. However, only a few of these have been introduced into clinical practice. Following the results of the controlled studies available, to date, the first-line treatment for endometriosis associated pain is still represented by oral contraceptives used continuously. Progestins represent an acceptable alternative. In women with rectovaginal lesions or colorectal endometriosis, norethisterone acetate at low dosage should be preferred. GnRH analogues may be used as second-line treatment, but significant side effects should be taken into account. Nonsteroidal anti-inflammatory drugs are widely used, but there is inconclusive evidence for their efficacy in relieving endometriosis-associated pelvic pain. Other agents such as GnRH antagonist, aromatase inhibitors, immunomodulators, selective progesterone receptor modulators, and histone deacetylase inhibitors seem to be very promising, but there is not enough evidence to support their introduction into routine clinical practice. Some other agents, such as peroxisome proliferator activated receptors-γ ligands, antiangiogenic agents, and melatonin have been proven to be efficacious in animal studies, but they have not yet been tested in clinical studies.

New and emerging contraceptives: a state-of-the-art review

Background

The first hormonal contraceptive was introduced onto the market in several countries 50 years ago; however, the portfolio of contraceptive methods remains restricted with regards to their steroid composition, their cost, and their ability to satisfy the requirements of millions of women/couples in accordance with their different reproductive intentions, behaviors, cultures, and settings.

Methods

A literature review was conducted using Medline, Embase, and Current Contents databases, up to September 1, 2013 to identify publications reporting new contraceptives in development using combinations of the search terms: contraception, contraceptives, oral contraceptives, patch, vaginal ring, implants, intrauterine contraceptives, and emergency contraception (EC). Also, several experts in the field were also consulted to document ongoing projects on contraception development. Additionally, the Clinicaltrial.gov website was searched for ongoing studies on existing contraceptive methods and new and emerging female contraceptives developed over the past 5 years. Information was also obtained from the pharmaceutical industry.

Results

Early sexual debut and late menopause means that women may require contraception for up to 30 years. Although oral, injectable, vaginal, transdermal, subdermal, and intrauterine contraceptives are already available, new contraceptives have been developed in an attempt to reduce side effects and avoid early discontinuation, and to fulfill women’s different requirements. Research efforts are focused on replacing ethinyl-estradiol with natural estradiol to reduce thrombotic events. In addition, new, less androgenic progestins are being introduced and selective progesterone receptor modulators and new delivery systems are being used. In addition, research is being conducted into methods that offer dual protection (contraception and protection against human immunodeficiency virus transmission), and contraceptives for use “on demand.” Studies are also investigating non-hormonal contraceptive methods that have additional, non-contraceptive benefits.

Conclusion

The most pressing need worldwide is, first, that the highly effective contraceptive methods already available should be affordable to most of the population and also that these methods should fulfill the needs of women of different ages and with different reproductive requirements. The development of new contraceptive methods should also take advantage of the knowledge obtained over the past 30 years on gamete physiology and gamete interaction to avoid the use of steroid compounds.

The potential of selective progesterone receptor modulators for the treatment of uterine fibroids

In addition to the estrogen receptor, the progesterone receptor plays an important role in the growth of uterine fibroids. Several selective progesterone receptor modulators (SPRMs) have been evaluated for medical treatment of uterine fibroids and, because of safety issues, some molecules were stopped during clinical development. However, in 2012, ulipristal acetate received the approval for a pre-surgical treatment of uterine fibroids. Clinical trials with ulipristal acetate for long-term medical treatment of uterine fibroids are ongoing. This review article describes the action of SPRMs at the progesterone receptor level and the mechanism of action on the fibroid tissue. A review of the published clinical trials is performed, including the current evidence of efficacy on uterine fibroid symptom management, size reduction and tolerability. The therapeutic potential of SPRMs for uterine fibroids is discussed.

A new therapeutic approach in the medical treatment of Cushing's syndrome: glucocorticoid receptor blockade with mifepristone

OBJECTIVE

Cushing's syndrome (CS) is a serious endocrine disorder caused by prolonged exposure to high cortisol levels. Initial treatment of this condition is dependent upon the cause, but is generally surgical. For patients whose hypercortisolism is not cured by surgery, medical therapy is often required. Drugs that have typically been used for CS medical therapy act by decreasing cortisol levels. Mifepristone is a glucocorticoid receptor antagonist now available for use in patients with CS. Unlike other agents, mifepristone does not decrease cortisol levels, but directly antagonizes its effects. Our objective is to review the pharmacology and clinical use of this novel agent and to discuss detailed guidance on the management of CS patients treated with mifepristone.

METHODS

We review the literature regarding mifepristone use in CS and recently published clinical trial data. Detailed information related to clinical assessment of mifepristone use, potential drug interactions, drug initiation and dose titration, and monitoring of drug tolerability are provided.

RESULTS

Clinical trial data have shown that mifepristone improves glycemic control and blood pressure, causes weight loss and a decrease in waist circumference, lessens depression, and improves overall wellbeing. However, adverse effects include adrenal insufficiency, hypokalemia, and endometrial thickening with vaginal bleeding. These findings are supported by the earlier literature case reports.

CONCLUSION

This article provides a review of the pharmacology and clinical use of mifepristone in Cushing's syndrome, as well as detailed guidance on the management of patients treated with this novel agent.

Treatment of Uterine Myoma with 2.5 or 5 mg Mifepristone Daily during 3 Months with 9 Months Posttreatment Followup: Randomized Clinical Trial

Objectives. To evaluate the efficacy, safety, and quality of life by using 2.5 and mifepristone 5 mg daily doses to treat uterine fibroids over 3 months with a 9-month followup period. Design. Randomized clinical trial. Place. “Eusebio Hernández” Hospital, Havana, Cuba. Subjects. 220 women with symptomatic uterine fibroids. Treatment. One-half (2.5 mg) or one-whole 5 mg mifepristone tablet. Variables to Evaluate Efficacy. Changes in fibroid and uterine volumes, in symptomatic prevalence and intensity, and in quality of life. Results. After 3-month treatment, fibroid volume decreased by 27.9% (CI 95% 20–35) and 45.5% (CI 95% 37–62), in the 2.5 and 5 mg groups, respectively, P = 0.003. There was no difference in the prevalence of symptoms at the end of treatment, unlike after 6- and 9-month followup when there was a difference. Amenorrhea was significantly higher in the 5 mg group, P = 0.001. There were no significant differences in mifepristone side effects between the groups. Both groups displayed a similar improvement in quality of life. Conclusions. The 2.5 mg dosage resulted in a lesser reduction in fibroid size but a similar improvement in quality of life when compared to the 5 mg dose. This trial is registered with ClinicalTrials.gov NCT01786226.

Mifepristone versus placebo to treat uterine myoma: a double-blind, randomized clinical trial

Objective

To evaluate the efficacy, safety, and quality of life of 5 mg mifepristone per day compared with a placebo in treating uterine fibroids.

Design

Randomized, double-blind clinical study.

Location

Eusebio Hernández Gynecology and Obstetrics Teaching Hospital, Havana, Cuba.

Subjects

One hundred twenty-four subjects with symptomatic uterine fibroids.

Treatment

One daily capsule of 5 mg mifepristone or a mifepristone placebo over 3 months.

Variables in evaluating safety

Changes in fibroid and uterine volumes, changes in symptom prevalence and intensity, and changes in quality of life.

Results

Three months into treatment, fibroid volume was reduced by 28.5% in the mifepristone group with an increase of 1.8% in the placebo group (P = 0.031). There were significant differences between the groups with respect to pelvic pain prevalence (P = 0.006), pelvic pressure (P = 0.027), rectal pain (P = 0.013), hypermenorrhea (P < 0.001), and metrorrhagia (P = 0.002) at the end of treatment. Amenorrhea was 93.1% and 4.3% in the mifepristone and placebo groups, respectively (P < 0.001). Treatment side effects were significantly greater in the mifepristone group. Estradiol levels did not differ significantly between the placebo and mifepristone groups at the end of treatment. Improvement in quality of life was significantly greater in the categories of “symptoms” (P = 0.004) and “activity” (P = 0.045) in the mifepristone group.

Conclusion

The 5 mg dosage of mifepristone presented significantly superior efficacy compared to the placebo.

Safety and effectiveness of different dosage of mifepristone for the treatment of uterine fibroids: a double-blind randomized clinical trial

Objectives

The aim of this study was to evaluate the safety and improvement in quality of life using 10 mg and 5 mg daily doses of mifepristone for the treatment of uterine fibroids.

Design

The research was a randomized double-blind clinical study undertaken at the Eusebio Hernández Hospital in Havana, Cuba.

Subjects and methods

Seventy subjects with symptomatic uterine fibroids took one daily capsule of 10 mg or 5 mg mifepristone orally for 9 months. One to three endometrial biopsies were performed. In evaluating safety, the variables studied were endometrial changes associated with mifepristone, elevation of hepatic transaminases, side effects of mifepristone, and instances and duration of irregular bleeding.

Results

There were 30/49 (61.2%) and 13/24 (54.2%) diagnoses of endometrial changes associated with mifepristone in the 10 mg and 5 mg groups, respectively (P = 0.282). At every evaluation visit the average endometrial thickness was significantly greater in the 10 mg group than in the 5 mg group (P = 0.013, P = 0.002, and P = 0.013, respectively). Only five subjects had slight elevations in their hepatic transaminases after 9 months’ treatment. Sixteen of 35 (45.7%) and eight of 33 (24.2%) subjects had the occasional hot flush in the 10 mg and 5 mg groups, respectively (P = 0.032). In total, there were 12.9 ± 4.6 (n = 21) and 9.1 ± 3.9 (n = 18) days of irregular bleeding in the 10 mg and 5 mg groups, respectively (P = 0.009).

Conclusion

According to the study findings, a 5 mg daily dose over 9 months has a relatively better safety profile than the 10 mg dose.

Value of 3-dimensional and power Doppler sonography for diagnosis of endometrial polyps

OBJECTIVES

To investigate whether the endometrial thickness, endometrial volume, and endometrial and subendometrial vascularization index, flow index, and vascularization-flow index were useful for diagnosing endometrial polyps in infertility.

METHODS

Transvaginal and 3-dimesional power Doppler sonography was performed to calculate the endometrial echogenicity, endometrial thickness, endometrial volume, and endometrial and subendometrial vascularization index, flow index, and vascularization-flow index, followed by hysteroscopy in the follicular phase of the menstrual cycle (postmenstrual days 3-7). A total of 555 patients were selected, and 4 groups were defined according to the comparison of sonographic and hysteroscopic diagnoses: group A (sonographically positive but hysteroscopically negative), group B (sonographically and hysteroscopically negative), group C (sonographically negative but hysteroscopically positive), and group D (sonographically and hysteroscopically positive).

RESULTS

A total of 426 patients were enrolled in the final analysis. Significantly higher endometrial thickness and volume were found in groups C and D compared with groups A and B (P < .05). There were no significant differences among the 4 groups in terms of the endometrial and subendometrial vascularization index, flow index, and vascularization-flow index (P > .05). The sensitivity, specificity, and positive and negative predictive values of endometrial thickness and volume in predicting endometrial polyps were 62.7%, 69.8%, 26.9%, and 91.9% and 39.3%, 88.2%, 35.8%, and 89.7%, respectively. Combined sonographic evaluation (sonographic echogenicity, endometrial thickness, and endometrial volume) showed higher sensitivity, specificity, and positive and negative predictive values (65.6%, 89.0%, 50.0%, and 93.9%) compared with a single indicator.

CONCLUSIONS

A combination of endometrial echogenicity, thickness, and volume on sonography may be better than a single indicator for predicting endometrial polyps in infertility. However, the endometrial or subendometrial vascularization index, flow index, and vascularization-flow index are not useful for prediction.

Progesterone and progesterone receptor modulators in the management of symptomatic uterine fibroids

The majority of symptomatic uterine fibroids are currently treated by surgical interventions (myomectomy or hysterectomy) or radiological treatments (uterine artery embolisation or focussed ultrasound surgery). None of these treatments is a panacea, and what is conspicuous is the lack of an effective long-term medical therapy for a disorder so common among women of reproductive age. It has been known for some time that progesterone and its receptors enhance proliferative activity in fibroids and this has raised the possibility that anti-progestins and (PRMs) could be useful in the medical management of fibroids. Some of the compounds which have produced promising results in recent clinical trials or research studies include mifepristone, CDB-4124 (telapristone), CP-8947, J-867 (asoprisnil) and CDB-2914 (ulipristal acetate or UA). UA has recently completed Phase III clinical trials with very encouraging results, and has now acquired a licence for clinical use in Europe. While considerable research has yet to be done on the long-term safety and efficacy of UA there is nevertheless good reason for optimism on the emergence of effective medical therapy in the form of UA and possibly other PRMs.

Ulipristal acetate: a novel option for the medical management of symptomatic uterine fibroids

Fibroids, the most common tumor in women of reproductive age, impact negatively on women's health and quality of life, and have significant cost implications for their management. The current mainstay treatments are surgical (myomectomy and hysterectomy) and more recently radiological (UAE and focused ultrasound surgery). Hysterectomy is curative but precludes future fertility, whereas the impact of the other treatments on reproduction is uncertain. With women in Western societies deferring childbearing to their 30s and 40s, when fibroids are most symptomatic, there is a pressing need for a uterus-sparing medical therapy that is cheap, effective, and enhances reproductive potential. Serendipity and meticulous translational research has shown that progesterone augments fibroid proliferation, raising the possibility that progesterone receptor modulators could inhibit fibroid growth; this research has culminated in the emergence of ulipristal acetate (UA), a first-in-class, oral selective progesterone receptor modulator (SPRM) that has successfully completed phase III clinical trials. It has been licensed in Western Europe for short-term clinical use prior to surgery, and has shown efficacy with a significant reduction in uterine bleeding, fibroid volume, and improved quality of life, without the side effects associated with other medications such as gonadotropin-releasing hormone (GnRH) agonists. As with all new medicines, there are concerns surrounding UA, not least its effect on the endometrium and the long-term impact on general health and reproduction. Research to date has tended to be industry led, and therefore, there is a need for researcher/clinician-led studies to address the wider issues concerning SPRMs. UA may not turn out to be the "Holy Grail" of medical therapy in the treatment of symptomatic uterine fibroids, but it has rightly given cause for a huge optimism. Further laboratory and clinical research into PRMs and related compounds will no doubt lead to more refined medications.

The role of progesterone signaling in the pathogenesis of uterine leiomyoma

Uterine leiomyomas are benign tumors that originate from the myometrium. Evidence points to ovarian steroid hormones, in particular, progesterone as major promoters of leiomyoma development and growth. While progesterone action in leiomyomas involves the classical nuclear receptor effects on gene regulation, there is growing evidence that signaling pathways are directly activated by the progesterone receptor (PR) and that PR can interact with growth factor signaling systems to promote proliferation and survival of leiomyomas. Studies investigating the genomic and non-genomic actions of PR and its role in leiomyoma growth are summarized here. Studies testing various selective progesterone receptor modulators for the treatment of leiomyomas are also highlighted. An increased understanding of the mechanisms associated with progesterone-driven growth of leiomyomas is critical in order to develop more efficient and targeted therapies for this prevalent disease.

The immninent dawn of SPRMs in obstetrics and gynecology

Selective progesterone receptor modulators (SPRMs) have been developed since the late 70s when mifepristone was first described. They act through nuclear progesterone receptors and can have agonist or mixed agonist antagonist actions depending on the cell and tissue. Mifepristone has unique major antagonist properties allowing its use for pregnancy termination. Ulipristal acetate has been marketed in 2009 for emergency contraception and has been recently approved for preoperative myoma treatment. Further perspectives for SPRMs use include long term estrogen free contraception, endometriosis treatment. However long term applications will be possible only after confirmation of endometrial safety.

Gene expression confirms a potentially receptive endometrium identified by histology in fertile women

BACKGROUND

To use contemporary biochemical markers to characterize mRNA/gene expression in the potentially fertile secretory endometrium to confirm its identification based on histological characteristics in order to develop a clinically applicable test.

METHODS

Nine, fertile, cycling Caucasian women were sampled from one IVF clinic. Endometrial samples were collected from them in two to four menstrual cycles at 2 and 7 days post first significant rise in blood LH. Separate endometrial glands and stroma populations were obtained by laser microdissection. Linear polymerase chain reaction amplified mRNAs which were hybridized to both Affymetrix U133 Plus2 and Agilent 4 × 44K microarrays followed by gene set analysis. Four histopathologists reviewed the sample set using the same histological criteria to date and characterize the non-receptive and potentially receptive samples.

RESULTS

mRNA expression of microdissected glands and stroma provided molecular signatures that characterized the two specific phases of the cycle with distinct clustering patterns. Cell proliferation and five other associated biological pathways were significantly down-regulated when the endometrium is considered potentially receptive accompanied by an increase in secreted glycoproteins mRNAs in the potentially receptive glands. Reported histological findings identified the presence of one histological feature characteristic of each phase: glandular mitoses indicated a non-receptive endometrium, whereas a potentially receptive endometrium was distinguished by supranuclear vacuolation.

CONCLUSIONS

This study defined a transcriptome characteristic of active cell proliferation in the non-receptive samples with a marked overall down-regulation of this pathway in potentially receptive samples-suggesting a transitional state associated with receptivity but not implantation. However, microarrays involve expensive, specialized testing and require significant post-data analysis. Sampling according to endocrinological and molecular prediction improved the consistency of histological assessment and allowed reliable histological markers of glandular mitosis in the non-receptive phase and supranuclear vacuolation of the potentially receptive endometrium to be identified. Thus, histology can provide an affordable, clinically applicable test in the context of reproduction.

Mifepristone 2.5 mg versus 5 mg daily in the treatment of leiomyoma before surgery

OBJECTIVES

To evaluate the efficacy and safety of 2.5 mg and 5 mg mifepristone during 3 months for the treatment of uterine fibroids before surgery.

DESIGN

Multicenter randomized clinical trial.

LOCATIONS

Eusebio Hernández Hospital, Havana, Cuba and the Alemán Hospital, Managua, Nicaragua.

SUBJECTS

Included in the study were 146 women with symptomatic uterine fibroids.

TREATMENT

GROUP I: half a tablet of 5 mg (2.5 mg) mifepristone taken orally every 24 hours, and Group II: one tablet of 5 mg mifepristone taken orally every 24 hours over a period of 3 months in both groups. Two endometrial biopsies were performed. VARIABLES TO EVALUATE EFFICACY: Increase in average hemoglobin, changes in fibroid and uterine volume, and symptomatic improvement.

RESULTS

The average hemoglobin at the end of treatment was 0.6 g/dL greater in the 5 mg mifepristone group (P = 0.033). In both groups there were similar reductions in fibroid volumes. Clinical improvement was more significant in the 5 mg group.

CONCLUSION

The dose to be used should be 5 mg.

Treatment of uterine myoma with 5 or 10mg mifepristone daily during 6 months, post-treatment evolution over 12 months: double-blind randomised clinical trial

OBJECTIVES

To evaluate the efficacy and safety of 5 and 10mg doses of mifepristone for 6 months for the treatment of uterine fibroids and to check those results at 1 year post-treatment.

STUDY DESIGN

Randomised double-blind clinical study carried out at the "Eusebio Hernández" Hospital, Havana, Cuba. One hundred and seventy-six women with symptomatic uterine fibroids received one daily capsule of 10mg mifepristone orally or one daily capsule of 5mg mifepristone orally, over 6 months. Up to two endometrial biopsies were performed. Reduction in fibroid volume was used to evaluate efficacy.

RESULTS

The 5 and 10mg dose had a similar efficacy in reducing the fibroid volume, 48.1% and 39.1%, p=0.07, and that of the uterus, 30.3% and 27.2%, p=0.63, respectively. Twelve months after treatment the majority of the subjects were asymptomatic with symptom prevalence similar to that at the end of treatment, except for hypermenorrhea and metrorrhagia, although the intensity of hypermenorrhea was much less, p<0.01.

CONCLUSIONS

(1) Both doses obtain similar results in reducing fibroid size. (2) Administering 6 months' treatment achieves symptomatic improvement lasting 1 year in a high percentage of cases. (3) More studies need to be carried out with longer treatment and follow-up periods.

Effects of a novel estrogen-free, progesterone receptor modulator contraceptive vaginal ring on inhibition of ovulation, bleeding patterns and endometrium in normal women

BACKGROUND

Progesterone receptor modulators (PRMs) delivered by contraceptive vaginal rings provide an opportunity for development of an estrogen-free contraceptive that does not require daily oral intake of steroids. The objective of this proof-of-concept study was to determine whether continuous delivery of 600-800 mcg of ulipristal acetate (UPA) from a contraceptive vaginal ring could achieve 80% to 90% inhibition of ovulation.

STUDY DESIGN

This was a prospective, controlled, open-labeled, multicenter international trial to examine the effectiveness and safety of this prototype vaginal ring. Thirty-nine healthy women, 21-40 years old and not at risk of pregnancy, were enrolled at three clinic sites. Volunteers participated in a control cycle, a 12-week treatment period and a post-treatment cycle. Pharmacodynamic effects on follicular function and inhibition of ovulation, effects on endometrium, bleeding patterns and serum UPA levels were evaluated.

RESULTS

Mean UPA levels during treatment were nearly constant, approximately 5.1 ng/mL throughout the study. Ovulation was documented in 32% of 111 "4-week treatment cycles." A correlation was observed between serum UPA and degree of inhibition of ovarian activity. There was no evidence of hyperplasia of endometrium, but PRM-associated endometrial changes were frequently observed (41%).

CONCLUSION

In this study, the minimum effective contraceptive dose was not established. Further studies are required testing higher doses of UPA to attain ovulation suppression in a higher percentage of subjects.

Current and future medical treatments for menometrorrhagia during the premenopause

Excessive menstrual bleeding reflects aberrant angiogenesis, generally due to submucosal myomas and endometrial polyps, although it is also frequently observed with long-term progestin-only contraception, impaired haemostasis and hormonal disorders. Surgery (hysterectomy, endometrial ablation) is used too frequently. Uterine artery embolisation is also an option for myomas. Medical treatments include combined oral contraception, progestins and levonorgestrel-releasing Intrauterine System. Gonadotropin-releasing hormone agonists provide significant improvements in bleeding for myomas, but also decrease estrogen secretion (e.g. hot flushes, decreased bone mass). Progestins, although used widely, remain poorly effective as they promote myoma cell growth. Recently, Selective Progesterone Receptor Modulators (SPRMs) have been shown to induce amenorrhea whilst maintaining endogenous estrogen secretion. Phase II studies have also demonstrated decreased fibroid size in SPRM-treated women. Although the mechanism of amenorrhea observed after SPRM treatment is still poorly understood, they may control uterine bleeding via a direct effect on endometrial blood vessels. Suppression of bleeding in women with uterine fibroids receiving SPRMs is associated with moderate reductions in uterine artery blood flow, without major changes in angiogenic factors and extracellular matrix composition; a clear difference to modifications observed with progestins. These data suggest major progress in the treatment of excessive menstrual bleeding.

Lessons learned from the preclinical drug discovery of asoprisnil and ulipristal for non-surgical treatment of uterine leiomyomas

INTRODUCTION

Uterine leiomyoma is the most common benign tumor in women during the reproductive years. Menorrhagia is the common symptom and accounts for the most frequent indication for hysterectomy. Thus, development of a novel drug for non-surgical treatment of uterine leiomyoma is needed for the betterment of women's health.

AREA COVERED

This review introduces a translational research initiated by use of the levonorgestrel-releasing intrauterine system (LNG-IUS) for contraceptive purposes. During follow-up, a patient informed that heavy menstrual bleeding caused by uterine myoma was strikingly reduced after the insertion of device. The patient's unexpected comment led the authors to perform clinical trials of LNG-IUS for the management of menorrhagia in women with uterine myomas and striking reduction in menorrhagia was obtained by the use of LNG-IUS. MRI examination, however, revealed that the volume of myomas decreased in some, but increased in the other instances. This unexpected finding with MRI directed the authors to characterize the effects of progesterone (P4) and progesterone receptor modulators (PRMs) on uterineleiomyoma cell growth in vitro.

EXPERT OPINION

In consistence with the in vitro data obtained, randomized controlled clinical trials of PRMs in patients with uterine leiomyomas at several institutions have demonstrated that oral administration of PRMs (asoprisnil and ulipristal) for 3 months reduced leiomyoma volume, resulting in a significant improvement of the associated symptoms. However, a novel pattern of PRM-associated endometrial changes was recognized in the endometrial pathology, demonstrating unusual epithelial types not seen in the normal menstrual cycle of a premenstrual woman. Thus, follow-up studies to determine whether the novel endometrial changes remain, disappear or progress to something else are needed for the possible long-term use of PRMs for the treatment of uterine leiomyoma.

Human uterine stem/progenitor cells: their possible role in uterine physiology and pathology

The human uterus mainly consists of the endometrium and the outer smooth muscle layer termed the myometrium. The uterus harbours the exceptional and remarkable regenerative ability responsible for cyclical regeneration and remodelling throughout the reproductive life. The uterus must swiftly and cooperatively enlarge to hold the growing foetus during pregnancy. Furthermore, the endometrium, in particular the functionalis layer, must also regenerate, differentiate and regress with each menstrual cycle under hormonal control. Endometrial regeneration from the basal layer is thought to contribute to replacement of the functionalis layer followed by its slough off during menses and parturition. These morphological and functional features of human endometrium can be reproduced in murine models in which severely immunodeficient mice are xenotransplanted with dispersed human endometrial cells under the kidney capsule. The uterine myometrium possesses the similar plasticity of the endometrium. This is demonstrated by multiple cycles of pregnancy-induced enlargement and regression after parturition. It is likely that regeneration and remodelling in the female reproductive tract are achieved presumably through endometrial and myometrial stem cell systems. Recent evidence now supports the existence of these stem cell systems in humans. Here, we will review our current understanding of uterine stem/progenitor cells. We also propose a novel hypothetical model in which stem cell activities explain the physiological remodelling and regeneration of the human uterus and the pathogenesis of gynaecological diseases such as endometriosis.

Endometrial changes from short-term therapy with CDB-4124, a selective progesterone receptor modulator

Selective progesterone receptor modulators are a class of drugs with progesterone antagonist activity that may confer therapeutic benefit for reproductive disorders in premenopausal women. Endometrial structure, which is dynamically controlled by circulating sex hormones, is likely to be perturbed by progesterone receptor modulators through their progesterone antagonist properties. We examined endometrial histology in 58 premenopausal women treated with the progesterone receptor modulator CDB-4124 (also known as Proellex) for endometriosis or uterine leiomyomata in two clinical trials. Endometrial biopsies obtained after 3 or 6 months with doses of 12.5, 25, or 50 mg daily oral CDB-4124 were reviewed independently by three pathologists. Consensus diagnoses using the World Health Organization hyperplasia scoring system, comments on specific histologic features, and clinical annotation were collected and analyzed. The majority of the endometrial biopsies (103 of 174 biopsies) contained histologic changes that are not seen during normal menstrual cycles. The histology of CDB-4124-treated patients was generally inactive or atrophic, and less frequently, proliferative or secretory, superimposed upon which were novel changes including formation of cystically dilated glands, and secretory changes coexisting with mitoses and apoptotic bodies. With increasing treatment dose and duration, the cysts became predominant and their lining inactive or atrophic. Cystic glands in the CDB-4124-treated subjects correlated with increased endometrial thickness by ultrasound. None of the CDB-4124-treated patients developed endometrial carcinoma or hyperplasia while on therapy. CDB-4124 therapy for 3-6 months produces histologic changes that are sufficiently novel that they might easily be misinterpreted by pathologists, particularly as disordered proliferative or hyperplastic endometrium. Knowledge of the constellation of endometrial changes associated with this agent and other progesterone receptor modulators, including cystic architecture and mixed non-physiologic epithelial changes will prevent misdiagnosis.