GnRH Antagonists with or without Add-Back Therapy: A New Alternative in the Management of Endometriosis?

The short- and mid-term efficacy and safety of elagolix in the management of pain associated with endometriosis: A systematic review and meta-analysis

BACKGROUND

Elagolix, an approved non-peptide GnRH antagonist, shows promise in relieving endometriosis-related pain, but its short- and mid-term efficacy and potential side effects are still under investigation.

OBJECTIVE

The aim is to provide data for therapeutic applications by methodically evaluating elagolix's safety and effectiveness in treating endometriosis-related pain.

METHODS

Databases such as PubMed, Embase, Cochrane Library, Web of Science, ClinicalTrials.gov, and others were thoroughly searched. The search time was from the establishment date to September 2023. The study included randomized controlled trials (RCTs) that compared the efficacy of elagolix versus placebo in treating endometriosis-associated pain. After data extraction and literature scanning, quality assessment was carried out using Quality evaluation was carried out using the bias risk assessment tool suggested by the Cochrane Reviewers' Handbook 5.1.0 after literature screening and data extraction. Stata 15.0 was used to do the meta-analysis.

RESULTS

In total, five RCTs involving 2056 patients were included in the analysis. The meta-analysis demonstrated a significant superiority of elagolix over placebo in the management of endometriosis-related pain, specifically in endometriosis pain [WMD=-0.77, 95% CI (-1.00, -0.53), P<0.001], as well as in non-menstrual pelvic pain, daily assessment of dysmenorrhea (DYS), and dyspareunia (DYSP), all of which are associated with endometriosis. Regarding safety, no discernible variation was observed in the incidence of serious adverse responses between the elagolix and placebo groups [RR=0.90, 95% CI (0.58, 1.40), P=0.643]. Conversely, the elagolix group exhibited a significantly higher incidence rate of general adverse responses [RR = 1.34, 95% CI (1.18, 1.52), P<0.001] compared to the control group.

CONCLUSIONS

The efficacy of elagolix in reducing pain in premenopausal women with endometriosis has been demonstrated over the short- to mid-term. However, careful monitoring for potential adverse effects is essential throughout the treatment duration.

Development and Application of a Physiologically Based Pharmacokinetic Model for Elagolix in the Adult and Adolescent Population

INTRODUCTION

Endometriosis, a common and distressing gynecological condition, affects fertility and causes pain, is often managed with medications such as Elagolix. The present study aimed to construct a physiologically based pharmacokinetic (PBPK) model for elagolix to predict its pharmacokinetics in different populations, including those with special conditions, to enhance treatment strategies for endometriosis.

METHODS

The PBPK model was optimized using observational data based on the oral administration of elagolix in a healthy Chinese population under fasting conditions. Model accuracy was further verified by comparing the predicted postprandial elagolix concentration data for healthy Chinese individuals with observed data and by comparing these values with the predicted values in a US population model with renal injury or following multiple-dose administration.

RESULTS

Elagolix pharmacokinetic (PK) profiles in the Chinese and American populations exhibited no differences that were attributable to ethnicity. The model predicted in vivo PK in adolescents aged 14-18 years, revealing no clinically significant differences in the effects of elagolix between adolescents and adults. In addition, no predicted PK differences in individuals with overweight were observed. However, notable variations emerged in those classified as obesity class 2 and above compared to healthy individuals.

CONCLUSION

Our study presents a novel PBPK model for elagolix in healthy Chinese women, addressing a clinical data gap for its use in adolescents and obese patients. By validating the model with real-world factors, including diet and renal impairment, we provide initial pharmacokinetic predictions for these populations, contributing to a more informed clinical approach.

Why do oestrogens matter: systematic review and meta-analysis assessing GnRH antagonists, considering add-back therapy, for endometriosis-associated pain

Gonadotrophin-releasing hormone (GnRH) antagonists have been demonstrated to reduce endometriosis-associated pain. Because of the hypo-oestrogenic state they induce, however, higher dosages of GnRH antagonists are not recommended for used long term. This unwanted effect may be eliminated by so-called add-back therapy (ABT). This review was conducted to assess the safety and efficacy of GnRH antagonists, with or without add-back hormonal replacement therapy. Out of the 345 studies selected through the initial search, seven randomized controlled trials were included, comparing different oral GnRH antagonists at varying dosages, from a minimum of 50 mg to a maximum of 200 mg once or twice daily. Women treated with the lowest dose of GnRH antagonists had significantly greater mean pain score reductions from baseline throughout treatment compared with those treated with placebo (odds ratio [OR] -13.12, 95% CI -17.35 to -8.89 and OR -3.08, 95% CI -4.39 to -1.76 for dysmenorrhoea and non-menstrual pelvic pain, respectively). Compatible with the dose-response effect, a positive correlation was found between response rates and adverse event rates. While GnRH antagonists offer an advantage in terms of pain reduction for endometriosis, the more recent literature suggests using GnRH antagonists with ABT, which, while mitigating the hypo-oestrogenic effects of GnRH antagonists, maintain their efficacy, while allowing their long-term use.

Advancements and Emerging Therapies in the Medical Management of Uterine Fibroids: A Comprehensive Scoping Review

Uterine fibroids, benign tumors originating from uterine smooth muscle cells, vary in prevalence depending on patient ethnicity, hormonal exposure, and genetics. Due to their high incidence, these neoplasms pose a significant burden on healthcare systems. Current treatment strategies range from routine monitoring in asymptomatic cases to surgical procedures such as myomectomy or hysterectomy in symptomatic patients, with an increasing trend toward uterus-preserving or non-surgical alternatives. This review examines the existing medical treatments for uterine fibroids and delves into the potential of emerging therapies. A scoping review of the literature was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews. Medical therapies are divided into hormonal and non-hormonal treatments; however, long-term, safe, and effective treatments in the treatment of uterine fibroids are limited. In addition to established therapies, there is an increasing number of studies investigating the effect of substances such as vitamin D or green tea extract on uterine fibroids. Some studies investigate acupuncture as a possible alternative therapy. While existing treatments offer symptomatic relief and preparation for surgery, our findings point to a significant need for further research into long-term solutions, especially owing to recent limitations in the use of ulipristal acetate due to risk of liver damage. Initial studies involving vitamin D and epigallocatechin gallate are encouraging; however, additional research is required to establish definitive therapeutic roles.

Linzagolix therapy versus a placebo in patients with endometriosis-associated pain: a prospective, randomized, double-blind, Phase 3 study (EDELWEISS 3)

STUDY QUESTION

Does linzagolix administered orally once daily for up to 3 months at a dose of 75 mg alone or 200 mg in combination with add-back therapy (ABT) (1.0 mg estradiol; 0.5 mg norethindrone acetate, also known as norethisterone acetate [NETA]) demonstrate better efficacy than placebo in the management of endometriosis-related dysmenorrhea and non-menstrual pelvic pain?

SUMMARY ANSWER

Combining 200 mg linzagolix with ABT was found to significantly reduce dysmenorrhea and non-menstrual pelvic pain at 3 months of therapy, while a daily dose of 75 mg linzagolix yielded a significant decrease only in dysmenorrhea at 3 months.

WHAT IS KNOWN ALREADY?

A previously published Phase 2, dose-finding study reported that at a dose of 200 mg daily, linzagolix promotes full suppression of estradiol secretion to serum levels below 20 pg/ml and noted that the addition of ABT may be needed to manage hypoestrogenic side effects. At lower doses (75 mg and 100 mg/day), linzagolix maintains estradiol values within the target range of 20-60 pg/ml, which could be ideal to alleviate symptoms linked to endometriosis.

STUDY DESIGN, SIZE, DURATION

EDELWEISS 3 was a multicenter, prospective, randomized, placebo-controlled, double-blind, double-dummy Phase 3 study to evaluate the safety and efficacy of linzagolix for the treatment of moderate-to-severe endometriosis-associated pain. Treatment was administered orally once daily for up to 6 months.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In the EDELWEISS 3 trial, 486 subjects with moderate-to-severe endometriosis-associated pain were randomized at a 1:1:1 ratio to one of the three study groups: placebo, 75 mg linzagolix alone or 200 mg linzagolix in association with ABT. Pain was measured daily on a verbal rating scale and recorded in an electronic diary.

MAIN RESULTS AND THE ROLE OF CHANCE

At 3 months, the daily 200 mg linzagolix dose with ABT met the primary efficacy objective, showing clinically meaningful and statistically significant reductions in dysmenorrhea and non-menstrual pelvic pain, with stable or decreased use of analgesics. The proportion of responders for dysmenorrhea in the 200 mg linzagolix with ABT group was 72.9% compared with 23.5% in the placebo group (P < 0.001), while the rates of responders for non-menstrual pelvic pain were 47.3% and 30.9% (P = 0.007), respectively. The 75 mg linzagolix daily dose demonstrated a clinically meaningful and statistically significant reduction in dysmenorrhea versus placebo at 3 months. The proportion of responders for dysmenorrhea in the 75 mg linzagolix group was 44.0% compared with 23.5% in the placebo group (P < 0.001). Although the 75 mg dose showed a trend toward reduction in non-menstrual pelvic pain at 3 months relative to the placebo, it was not statistically significant (P = 0.279). Significant improvements in dyschezia and overall pelvic pain were observed in both linzagolix groups when compared to placebo. Small improvements in dyspareunia scores were observed in both linzagolix groups but they were not significant. In both groups, hypoestrogenic effects were mild, with low rates of hot flushes and bone density loss of <1%. A daily dose of 200 mg linzagolix with ABT or 75 mg linzagolix alone was found to significantly reduce dysmenorrhea and non-menstrual pelvic pain also at 6 months of therapy.

LIMITATIONS, REASONS FOR CAUTION

Efficacy was compared between linzagolix groups and placebo; however, it would be useful to have results from comparative studies with estro-progestogens or progestogens. It will be important to ascertain whether gonadotropin-releasing hormone antagonists have significant benefits over traditional first-line medications.

WIDER IMPLICATIONS OF THE FINDINGS

Linzagolix administered orally once daily at a dose of 200 mg in combination with add-back therapy (ABT) demonstrated better efficacy and safety than placebo in the management of moderate-to-severe endometriosis-associated pain. The quality of life was improved and the risks of bone loss and vasomotor symptoms were minimized due to the ABT. The 75 mg dose alone could be suitable for chronic treatment of endometriosis-associated pain without the need for concomitant hormonal ABT, but further research is needed to confirm this. If confirmed, it would offer a viable option for women who do not want to wish to have ABT or for whom it is contraindicated.

STUDY FUNDING/COMPETING INTEREST(S)

Funding for the EDELWEISS 3 study was provided by ObsEva (Geneva, Switzerland). Analysis of data and manuscript writing were partially supported by ObsEva (Geneva, Switzerland), Theramex (London, UK) and Kissei (Japan) and grant 5/4/150/5 was awarded to M.-M.D. by FNRS. J.D. was a member of the scientific advisory board of ObsEva until August 2022, a member of the scientific advisory board of PregLem, and received personal fees from Gedeon Richter, ObsEva and Theramex. J.D. received consulting fees, speakers' fees, and travel support from Gedeon Richter, Obseva and Theramex, which was paid to their institution. C.B. has received fees from Theramex, Gedeon Richter, and Myovant, and travel support from Gedeon Richter-all funds went to the University of Oxford. He was a member of the data monitoring board supervising the current study, and served at an advisory board for endometriosis studies of Myovant. H.T. has received grants from Abbvie and was past president of ASRM. F.C.H. has received fees from Gedeon Richter and Theramex. O.D. received fees for lectures from Gedeon Richter and ObsEva and research grants for clinical studies from Preglem and ObsEva independent from the current study. A.H. has received grants from NIHR, UKRI, CSO, Wellbeing of Women, and Roche Diagnostics; he has received fees from Theramex. A.H.'s institution has received honoraria for consultancy from Roche Diagnostics, Gesynta, and Joii. M.P. has nothing to declare. F.P. has received fees from Theramex. S.P.R. has been a member of the scientific advisory board of Gedeon Richter and received fees from Gedeon Richter. A.P. and M.B. are employees of Theramex. E.B. was an employee of ObsEva, sponsor chair of the data monitoring board supervising the current study, and has been working as a consultant for Theramex since December 2022; she owns stock options in ObsEva. M.-M.D. has received fees and travel support from Gedeon Richter and Theramex.

TRIAL REGISTRATION NUMBER

NCT03992846.

TRIAL REGISTRATION DATE

20 June 2019.

DATE OF FIRST PATIENT’S ENROLLMENT

13 June 2019.

Do we want to know the enormity of women's severe menstrual disorders and chronic pelvic pain?

OBJECTIVE

The purpose of this paper is to call for a nationwide study to assess the prevalence and incidence of women health problems related to menstrual disorders and severe pelvic pain.

RATIONALE

The exact prevalence and incidence of endometriosis, adenomyosis, severe painful menstrual disorders, and of severe chronic pelvic pain are unknown. These issues severely impact women's quality of life and represent huge costs for our societies. Using adapted questionnaires, recent progresses in diagnosis and increased fundings announced by politicians, we can and should change this situation by performing a nationwide study to assess prevalence and incidence of these women problems in the French general population. The huge, anticipated costs of this study do appear quite reasonable when accounting for the enormous costs and societal consequences of endometriosis, menstrual disorders and severe pelvic pain.

CONCLUSION

These long-awaited data will improve our understanding of the causes, consequences, and natural history of endometriosis. These data will allow women to better understand that pain is not always related to endometriosis, thus preventing unjustified fears. Physicians will be able to adapt and improve medical managements, particularly the diagnosis. Politicians will have the tools to improve women's health and gender equality.

Experimental and new investigational drugs for the treatment of uterine fibroids

INTRODUCTION

Uterine fibroids, the most prevalent benign tumors among reproductive-age women, pose treatment challenges that range from surgical interventions to medical therapies for symptom control. Progestins and estroprogestins effectively manage uterine bleeding by suppressing dysfunctional endometrium over fibroids. While GnRH agonists represent a crucial milestone in symptom treatment, their prolonged use results in menopausal-like symptoms and irreversible bone mineral density loss. Advancements in understanding fibroid pathophysiology have prompted the exploration of new compounds to overcome current therapy limitations.

AREAS COVERED

This manuscript offers an updated overview of investigational drugs for symptomatic uterine fibroids.

EXPERT OPINION

Despite ulipristal acetate's well-established efficacy as a selective progesterone receptor modulator (SPRM) in fibroid treatment, its prescription has declined due to the rare but severe risk of liver damage. Oral GnRH antagonists, like elagolix, relugolix, and linzagolix, with their novel pharmacodynamic properties, are gaining traction in fibroid management, inducing a dose-dependent reduction in circulating sex hormone levels. Ongoing research on natural compounds, such as vitamin D and epigallocatechin gallate (EGCG), presents emerging options for treating uterine fibroids. This evolving landscape reflects the ongoing efforts to improve therapeutic outcomes for individuals with symptomatic uterine fibroids.

Horizons in Endometriosis: Proceedings of the Montreux Reproductive Summit, 14-15 July 2023

Endometriosis is a complex and chronic gynaecological disorder that affects millions of women worldwide, leading to significant morbidity and impacting reproductive health. This condition affects up to 10% of women of reproductive age and is characterised by the presence of endometrial-like tissue outside the uterus, potentially leading to symptoms such as chronic pelvic pain, dysmenorrhoea, dyspareunia, and infertility. The Montreux summit brought a number of experts in this field together to provide a platform for discussion and exchange of ideas. These proceedings summarise the six main topics that were discussed at this summit to shed light on future directions of endometriosis classification, diagnosis, and therapeutical management. The first question addressed the possibility of preventing endometriosis in the future by identifying risk factors, genetic predispositions, and further understanding of the pathophysiology of the condition to develop targeted interventions. The clinical presentation of endometriosis is varied, and the correlation between symptoms severity and disease extent is unclear. While there is currently no universally accepted optimal classification system for endometriosis, several attempts striving towards its optimisation - each with its own advantages and limitations - were discussed. The ideal classification should be able to reconcile disease status based on the various diagnostic tools, and prognosis to guide proper patient tailored management. Regarding diagnosis, we focused on future tools and critically discussed emerging approaches aimed at reducing diagnostic delay. Preserving fertility in endometriosis patients was another debatable aspect of management that was reviewed. Moreover, besides current treatment modalities, potential novel medical therapies that can target underlying mechanisms, provide effective symptom relief, and minimise side effects in endometriotic patients were considered, including hormonal therapies, immunomodulation, and regenerative medicine. Finally, the question of hormonal substitution therapy after radical treatment for endometriosis was debated, weighing the benefits of hormone replacement.

Oral GnRH Antagonists in Combination with Estradiol and Norethindrone Acetate for Pain Relief Associated with Endometriosis: A Review of Evidence of a Novel Class of Hormonal Agents

Current medical treatment options for endometriosis associated pains are inadequate. Evidence on effects of nonsteroidal anti-inflammatory drugs is scarce. Around one third of patients are not responsive to oral contraceptives or progestins due to progesterone resistance. Gonadotropin-releasing hormone (GnRH) agonists can only be used for a short duration because of associated side effects. Oral GnRH antagonists, including elagolix, relugolix, and linzagolix allow oral administration, induce dose dependent reduction of estradiol levels, do not cause initial flare up of endometriosis symptoms, and allow the fast return of ovarian function and menstruation after discontinuation. Elagolix at a low dose of 150 mg once daily, or the higher dose of 200 mg twice daily, significantly increased the proportion of women achieving clinically meaningful decline of dysmenorrhea, noncyclic pelvic pain, and dyspareunia. Relugolix at an oral dose of 40 mg/day results in improvement in different forms of endometriosis related pelvic pain, with an efficacy and side effect profile similar to that of GnRH agonists. Adding 1 mg of estradiol and 0.5 mg of norethindrone to 40 mg of relugolix (relugolix combination therapy) allows extension of treatment to 24 weeks with maintained efficacy and an improved side effect profile. Linzagolix, in a dose of 75 mg/day, can be used alone to treat endometriosis associated pain. For severe pelvic pain and dyspareunia, linzagolix can be used in a high dose of 200 mg/day with hormonal add-back therapy to preserve bone health.

Perception and Comfort with Endometriosis Management Among OB/GYN Residents

Purpose

The diagnosis of endometriosis often takes several years, delaying appropriate care while patients suffer from pelvic pain, dysmenorrhea, and dyspareunia. Understanding whether residents in obstetrics and gynecology (OB/GYN) are being adequately exposed to and trained in the diagnosis and management of the disease is important for improving care.

Methods

We conducted an online cross-sectional survey of OB/GYN residents to investigate their comfort level and familiarity with endometriosis diagnosis and management. Residency program directors and coordinators of 20 OB/GYN residency programs in California, USA were emailed to disseminate the 31-question, anonymous survey in January to February 2023. Responses were collected using Redcap and analysis was conducted using STATA.

Results

67 residents answered at least one non-demographic question and were included. A resident response rate was not calculated because we were unable to determine how many programs distributed the survey. 84% of residents felt they could recognise symptoms of endometriosis but over 30% of senior residents were not comfortable with sonographic diagnosis of endometrioma. Approximately one third of residents felt comfortable managing hypoestrogenic symptoms, osteoporotic risks, and add-back progestin for certain hormonal therapies. Academic-hospital based residents had significantly more exposure to attendings prescribing long-acting reversible contraception, GnRH antagonists, and GnRH agonists but there were no significant differences in trainee prescribing practices or comfort. More respondents would feel comfortable medically managing endometriosis (52%) than surgically managing the disease (26%) if they were in practice today, with only 39% of PGY3-4 residents feeling comfortable surgically managing endometriosis.

Conclusion

There is considerable room for improvement in the education of residents in the diagnosis and medical and surgical management of endometriosis.

Cannabis and Endometriosis: The Roles of the Gut Microbiota and the Endocannabinoid System

Endometriosis, a chronic condition affecting around 10-14% of women, is challenging to manage, due to its complex pathogenesis and limited treatment options. Research has suggested a potential role of the gut microbiota and the endocannabinoid system in the development and progression of endometriosis. This narrative review aims to explore the role of, and any potential interactions between, the endocannabinoid system (ECS) and the gut microbiota in endometriosis. This review found that both the ECS and microbiota influence endometriosis, with the former regulating inflammation and pain perception and the latter influencing immune responses and hormonal balance. There is evidence that a dysregulation of the endocannabinoid system and the gut microbiota influence endometriosis symptoms and progression via changes in CB1 receptor expression and increased circulating levels of endocannabinoids. Microbial imbalances in the gut, such as increases in Prevotella, have been directly correlated to increased bloating, a common endometriosis symptom, while increases in E. coli have supported the bacterial contamination hypothesis as a potential pathway for endometriosis pathogenesis. These microbial imbalances have been correlated with increases in inflammatory markers such as TNF-α and IL-6, both often raised in those with endometriosis. Protective effects of the ECS on the gut were observed by increases in endocannabinoids, including 2-AG, resulting in decreased inflammation and improved gut permeability. Given these findings, both the ECS and the gut microbiota may be targets for therapeutic interventions for endometriosis; however, clinical studies are required to determine effectiveness.

Update on the management of endometriosis-associated pain in France

The French National College of Obstetricians and Gynecologists (CNGOF) published guidelines for managing endometriosis-associated pain in 2018. Given the development of new pharmacological therapies and a review that was published in 2021, most national and international guidelines now suggest a new therapeutic approach. In addition, a novel validated screening method based on patient questionnaires and analysis of 109-miRNA saliva signatures, which combines biomarkers and artificial intelligence, opens up new avenues for overcoming diagnostic challenges in patients with pelvic pain and for avoiding laparoscopic surgery when sonography and MRI are not conclusive. Dienogest (DNG) 2 mg has been a reimbursable healthcare expense in France since 2020, and, according to recent studies, it is at least as effective as combined hormonal contraception (CHC) and can be used as an alternative to CHC for first-line treatment of endometriosis-associated pain. Since 2018, the literature concerning the use of DNG has grown considerably, and the French guidelines should be modified accordingly. The levonorgestrel intrauterine system (LNG IUS) and other available progestins per os, including DNG, or the subcutaneous implant, can be offered as first-line therapy, gonadotropin-releasing hormone (GnRH) agonists with add-back therapy (ABT) as second-line therapy. Oral GnRH antagonists are promising new medical treatments for women with endometriosis-associated pain. They competitively bind to GnRH receptors in the anterior pituitary, preventing native GnRH from binding to GnRH receptors and from stimulating the secretion of luteinizing hormone and follicle-stimulating hormone. Consequently, estradiol and progesterone production is reduced. Oral GnRH antagonists will soon be on the market in France. Given their mode of action, their efficacy is comparable to that of GnRH agonists, with the advantage of oral administration and rapid action with no flare-up effect. Combination therapy with ABT is likely to allow long-term treatment with minimal impact on bone mass. GnRH antagonists with ABT may thus be offered as second-line treatment as an alternative to GnRH agonists with ABT. This article presents an update on the management of endometriosis-associated pain in women who do not have an immediate desire for pregnancy.

Efficacy and safety of oral gonadotropin-releasing hormone antagonists in moderate-to-severe endometriosis-associated pain: a systematic review and network meta-analysis

PURPOSE

The aim of this NMA is to comprehensively analyze evidence of oral GnRH antagonist in the treatment of moderate-to-severe endometriosis-associated pain.

METHODS

Literature searching was performed to select eligible studies published prior to April 2022 in PubMed, Cochrane, Embase and Web of Science. Randomized controlled trials involving patients who suffered from moderate-to-severe endometriosis-associated pain and treated with oral nonpeptide GnRH antagonists or placebo were included.

RESULTS

Elagolix 400 mg and ASP1707 15 mg were most efficient in reducing pelvic pain, dysmenorrhea and dyspareunia. Relugolix 40 mg was best in reducing the analgesics use. The rates of any TEAEs and TEAEs-related discontinuation were highest in relugolix 40 mg and elagolix 250 mg, respectively, while rates of hot flush and headache were highest in relugolix 40 mg and elagolix 150 mg. Significantly decreased spinal BMD was observed in elagolix 250 mg.

CONCLUSION

Oral GnRH antagonists were effective in endometriosis-associated pain in 12w, and most of the efficiency and safety outcomes were expressed in a dose-dependent manner, but linzagolix 75 mg was an exception.

Epigenetics, endometriosis and sex steroid receptors: An update on the epigenetic regulatory mechanisms of estrogen and progesterone receptors in patients with endometriosis

Endometriosis is a benign gynecological disease affecting ∼10% of reproductive-aged women and is defined as the presence of endometrial glands and stroma outside the uterine cavity. Endometriosis can cause a variety of health problems, from pelvic discomfort to catamenial pneumothorax, but it's mainly linked with severe and chronic pelvic pain, dysmenorrhea, and deep dyspareunia, as well as reproductive issues. The pathogenesis of endometriosis involves an endocrine dysfunction, with estrogen dependency and progesterone resistance, and inflammatory mechanism activation, together with impaired cell proliferation and neuroangiogenesis. The present chapter aims to discuss the main epigenetic mechanisms related to estrogen receptors (ERs) and progesterone receptors (PRs) in patients with endometriosis. There are numerous epigenetic mechanisms participating in endometriosis, regulating the expression of the genes encoding these receptors both indirectly, through the regulation of transcription factors, and directly, through DNA methylation, histone modifications, micro RNAs and long noncoding RNAs. This represents an open field of investigation, which may lead to important clinical implications such as the development of epigenetic drugs for the treatment of endometriosis and the identification of specific and early biomarkers for the disease.

Profile of Linzagolix in the Management of Endometriosis, Including Design, Development and Potential Place in Therapy: A Narrative Review

Estrogens play a critical role in the pathogenesis of endometriosis and it is logical to assume that lowering estradiol levels with oral gonadotropin-releasing hormone (GnRH) antagonists may prove effective, especially in women who fail to respond to progestogens. Indeed, due to progesterone resistance, oral contraceptives and progestogens work well in two-thirds of women suffering from endometriosis, but are ineffective in 33% of women. Oral GnRH antagonists have therefore been evaluated for management of premenopausal women with endometriosis-associated pelvic pain. The first publication on these drugs reported the efficacy of elagolix. The present paper is a narrative review of linzagolix, which is an orally administered GnRH receptor antagonist with low pharmacokinetic/pharmacodynamic variability. It binds to and blocks the GnRH receptor in the pituitary gland, resulting in a dose-dependent drop in luteinizing hormone (LH) and follicle-stimulating hormone (FSH) production. This reduction in LH and FSH levels in turn leads to a dose-dependent decline in estrogen. Phase 2 and 3 trials are reviewed and discussed here. There is a place for GnRH antagonists in the management of symptomatic endometriosis, and linzagolix with or without add-back therapy (ABT) is one option that can be used at low doses, avoiding the need for ABT, which is contraindicated in some patients.

Gonadotropin-Releasing Hormone Antagonists-A New Hope in Endometriosis Treatment?

Endometriosis is a chronic disease, in which endometrial-like tissue is found outside the uterine cavity. Lesions are typically located in the true pelvis but can be found, in addition to extragenital endometriosis, in the respiratory system, the diaphragm, the pleura or the pericardium. As the extrauterine endometrial lesions undergo the menstrual cycle, they cause many symptoms, including pain, and besides infertility, they all mostly affect the quality of the patient's life. Pharmacological management of endometriosis significantly increases in importance either as a first-line treatment or as a complementary therapy after surgery. Yet, current research on antagonists of the gonadotropin-releasing hormone (GnRH) has revealed their potential benefits in endometriosis treatment. Their mechanism of action is to down-regulate the hypothalamic-pituitary-gonadal axis and therefore induce a hypoestrogenic state. The resulting reduction of estrogen levels prevents disease progression and diminishes the recurrence rate after surgical removal of endometriosis. The present review summarizes recent reports of the role oral GnRH antagonists have as a significant treatment option for pain reduction in endometriosis patients.

Emerging Drug Targets for Endometriosis

Endometriosis is a chronic inflammatory disease causing distressing symptoms and requiring a life-long management strategy. The objective of this review is to evaluate endometriosis-related pathways and identify novel therapies to treat it. We focused on the crucial role of inflammation and inflammatory molecules in order to define new perspectives for non-hormonal treatment of the disease by targeting inflammation, nuclear factor kappa B and cytokines, or reactive oxygen species, apoptotic and autophagic pathways, regulators of epithelial-mesenchymal transition, and angiogenesis and neuroangiogenesis. Novel non-steroidal therapies targeting these pathways for endometriosis were explored, but multiple challenges remain. While numerous agents have been investigated in preclinical trials, few have reached the clinical testing stage because of use of inappropriate animal models, with no proper study design or reporting of preclinical strategies. Targeting estrogens is still the best way to control endometriosis progression and inflammation.

Advances in targeting estrogen synthesis and receptors in patients with endometriosis

INTRODUCTION

Endometriosis is an estrogen-dependent disease on the background of progesterone resistance. Increased estrogen production, low estrogen metabolization, and altered estrogen receptors (ERs) expression contribute to the hyperestrogenic milieu within endometriotic lesions. Since estrogens play a crucial role in the pathogenesis of the disease, inhibition of estrogen production is one of the main targets of available and emerging drugs.

AREAS COVERED

Firstly, we described the molecular alterations responsible for estrogen dependence. Secondly, we reviewed available and emerging treatments that interfere, through central (gonadotropin-releasing hormone analogs (GnRH-a), GnRH antagonists) or local mechanisms (aromatase inhibitors (AIs), inhibitors of steroid sulfatase (STS) and hydroxysteroid dehydrogenase type 1 (17β-HSD1)), with estrogen dependence. Finally, we focused on emerging treatments targeting ERs (selective estrogen receptor modulators (SERMs), estrogen receptors agonists, and antagonists).

EXPERT OPINION

Available treatments interfering with estrogen pathways exert a contraceptive effect, have hypoestrogenic side effects, and cannot prevent or definitively treat the disease. Preclinical and animal studies are focusing on emerging drugs targeting ERs in order to overcome limitations of available treatments. These treatments may represent a promising option, as they may produce a more specific inhibition of disease activity within endometriotic implants, avoiding prolonged hypoestrogenic status and limiting systemic side effects.

Linzagolix: First Approval

Linzagolix (Yselty^®) is an orally administered, selective, non-peptide small molecule gonadotrophin releasing hormone (GnRH) receptor antagonist that is being developed by Kissei Pharmaceutical for the treatment of uterine fibroids and endometriosis in women of reproductive age. Linzagolix binds to and blocks the GnRH receptor in the pituitary gland, modulating the hypothalamic pituitary-gonadal axis and dose-dependently reducing serum luteinising hormone and follicle-stimulating hormone production and serum estradiol levels. In June 2022, linzagolix was approved for the treatment of moderate to severe symptoms of uterine fibroids in adult women of reproductive age in the EU. Linzagolix is under regulatory review the USA for this indication and is in phase 3 clinical development in the treatment of pain associated with endometriosis. This article summarizes the milestones in the development of linzagolix leading to this first approval for the treatment of moderate to severe symptoms of uterine fibroids in adult women of reproductive age.

Salvia miltiorrhiza-Containing Chinese Herbal Medicine Combined With GnRH Agonist for Postoperative Treatment of Endometriosis: A Systematic Review and meta-Analysis

Background: Endometriosis is an estrogen-dependent gynecological inflammatory condition that may lead to infertility and recurrent pelvic pain. The purpose of this research was to determine the efficacy and safety of Salvia miltiorrhiza-containing Chinese herbal medicine (CHM) combined with gonadotropin-releasing hormone agonist (GnRH-a) for postoperative endometriosis management. Methods:Eight databases were systematically searched before October 2021, including PubMed, Embase, Cochrane Library, Scopus, Web of Sceince, CNKI, VIP, and Wanfang. Finally, all randomized controlled studies comparing Salvia miltiorrhiza-containing CHM paired with GnRH-a to GnRH-a alone for postoperative endometriosis management were included. Results: A total of 10 trials involving 836 patients were reported and analyzed. Compared with the control group, the Salvia miltiorrhiza-containing CHM combined with GnRH-a group showed significant superiority in decreasing endometriosis recurrence (risk ratio [RR] = 0.26; 95% confidence intervals [CI]: 0.16-0.41) and increasing the pregnancy rate ([RR] = 1.96; 95% CI: 1.58-2.44). Similarly, the effect of the Salvia miltiorrhiza-containing CHM combined with GnRH-a on CA-125 serum levels was positive (standardized mean difference [SMD] = -0.79; 95% CI: -1.11 to -0.47). Furthermore, this group showed a significant reduction in adverse effects. Conclusion: The results indicate that Salvia miltiorrhiza-containing CHM may be a viable choice for postoperative endometriosis therapy, with the potential to enhance pregnancy while decreasing recurrence and adverse effects.

Conservative Management of Rectovaginal Deep Endometriosis: Shaving Should Be Considered as the Primary Surgical Approach in a High Majority of Cases

Deep endometriosis infiltrating the rectum remains a challenging situation to manage, and it is even more important when ureters and pelvic nerves are also infiltrated. Removal of deep rectovaginal endometriosis is mandatory in case of symptoms strongly impairing quality of life, alteration of digestive, urinary, sexual and reproductive functions, or in case of growing. Extensive preoperative imaging is required to choose the right technique between laparoscopic shaving, disc excision, or rectal resection. When performed by skilled surgeons and well-trained teams, a very high majority of cases of deep endometriosis nodule (>95%) is feasible by the shaving technique, and this is associated with lower complication rates regarding rectal resection. In most cases, removing a part of the rectum is questionable according to the risk of complications, and the rectum should be preserved as far as possible. Shaving and rectal resection are comparable in terms of recurrence rates. As shaving is manageable whatever the size of the lesions, surgeons should consider rectal shaving as first-line surgery to remove rectal deep endometriosis. Rectal stenosis of more than 80% of the lumen, multiple bowel deep endometriosis nodules, and stenotic sigmoid colon lesions should be considered as indication for rectal resection, but this represents a minority of cases.

Pathogenesis of Endometriosis: New Insights into Prospective Therapies

Endometriosis is a female reproductive disorder characterized by growth of uterine cells and tissue in distant sites. Around 2-10% of women experience this condition during reproductive age, 35-50% of whom encounter fertility issues or pain. To date, there are no established methods for its early diagnosis and treatment, other than surgical procedures and scans. It is difficult to identify the disease at its onset, unless symptoms such as infertility and/or pain are present. Determining the mechanisms involved in its pathogenesis is vital, not only to pave the way for early identification, but also for disease management and development of less invasive but successful treatment strategies. Endometriosis is characterized by cell proliferation, propagation, evasion of immunosurveillance, and invasive metastasis. This review reports the underlying mechanisms that are individually or collectively responsible for disease establishment and evolution. Treatment of endometriosis mainly involves hormone therapies, which may be undesirable or have their own repercussions. It is therefore important to devise alternative strategies that are both effective and cause fewer side effects. Use of phytochemicals may be one of them. This review focuses on pharmacological inhibitors that can be therapeutically investigated in terms of their effects on signaling pathways and/or mechanisms involved in the pathogenesis of endometriosis.