Committee Opinion No. 663: Aromatase Inhibitors in Gynecologic Practice

Low-dose letrozole - an effective option for women with symptomatic adenomyosis awaiting IVF: a pilot randomized controlled trial

RESEARCH QUESTION

Can low-dose letrozole reduce dysmenorrhoea, menorrhagia and sonographic features in symptomatic women with adenomyosis awaiting IVF?

DESIGN

This was a longitudinal randomized prospective pilot study to explore the effectiveness of low-dose letrozole and compare it with a gonadotropin releasing hormone (GnRH) agonist in reducing dysmenorrhoea, menorrhagia and sonographic features in symptomatic women with adenomyosis awaiting IVF. The women were treated for 3 months, either with the GnRH agonist goserelin 3.6 mg/month (n = 77) or the aromatase inhibitor letrozole 2.5 mg three times weekly (n = 79). Dysmenorrhoea and menorrhagia were evaluated at randomization and followed up monthly using a visual analogue score (VAS) and pictorial blood loss assessment chart (PBAC), respectively. A quantitative scoring method was used to assess the improvement of sonographic features after 3 months of treatment.

RESULTS

Both groups reported a marked improvement in symptoms after 3 months of treatment. In both the letrozole and GnRH agonist groups, VAS and PBAC scores decreased significantly over the 3 months (letrozole: P = 0.0001 and P = 0.0001 for VAS and PBAC, respectively; GnRH agonist: P = 0.0001 and P = 0.0001 for VAS and PBAC, respectively). Participants on letrozole had regular menstruation cycles, while most of the women who received the GnRH agonist were amenorrhoeic, with only four women reporting mild bleeding. Haemoglobin concentrations also improved after both treatments (letrozole P = 0.0001, GnRH agonist P = 0.0001). A quantitative assessment of sonographic features showed significant improvements following both treatments (diffuse adenomyosis of the myometrium: letrozole P = 0.015, GnRH agonist P = 0.039; diffuse adenomyosis of the junctional zone: letrozole P = 0.025, GnRH agonist P = 0.001). Women with adenomyoma also responded well to both therapies (letrozole P = 0.049, GnRH agonist P = 0.024), whereas the letrozole group responded comparatively better in focal adenomyosis when the outer myometrium was involved (letrozole P < 0.001, GnRH agonist P = 0.26). No noticeable side effects were observed in women receiving letrozole therapy. Additionally, letrozole therapy was found to be more cost-effective than GnRH agonist treatment.

CONCLUSIONS

Low-dose letrozole treatment is a low-cost alternative to a GnRH agonist, with comparable effects in improving the symptoms and sonographic features of adenomyosis in women awaiting IVF.

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.

The impact of estradiol on pregnancy outcomes in letrozole-stimulated frozen embryo transfer cycles

Objective

To assess the impact of low estradiol (E2) levels in letrozole-stimulated frozen embryo transfer (FET) cycles on pregnancy and neonatal outcomes.

Design

Retrospective cohort.

Setting

University-affiliated fertility center.

Patients

All patients who underwent letrozole-stimulated FET cycles from January 2017 to April 2020 (n = 217). The "Low E2" group was defined as those with E2 serum levels on the day of trigger <10th percentile level (E2 <91.16 pg/mL, n = 22) and the "Normal E2" group was defined as those with E2 serum levels ≥10th percentile level (E2 ≥91.16 pg/mL, n = 195).

Interventions

None.

Main Outcome Measures

Pregnancy outcomes including rates of clinical pregnancy, clinical miscarriage, and live birth. Neonatal outcomes including gestational age at delivery, birth weight, and Apgar score.

Results

The mean ± SD estradiol level was 66.8 ± 14.8 pg/mL for the "Low E2" group compared with 366.3 ± 322.1 pg/mL for the "Normal E2" group. There were otherwise no substantial differences in cycle characteristics such as endometrial thickness on the day of ovulation trigger and progesterone levels in early pregnancy. The "Low E2" group had a significantly higher clinical miscarriage rate (36.4% vs. 8.8%, adjusted odds ratio 8.06) and lower live birth rate (31.8% vs. 57.9%, adjusted odds ratio 0.28). Neonatal outcomes such as gestational age at delivery, mean birth weight, Apgar scores, and incidence of newborn complications were not clinically different between the groups.

Conclusion

Low E2 levels were associated with a significantly higher miscarriage rate and lower live birth rate, suggesting that E2 levels in the follicular phase may have an effect on cycle outcomes. Given the rise in use of FET, further studies are needed to confirm our findings and understand the mechanisms.

Anastrozole and levonorgrestrel-releasing intrauterine device in the treatment of endometriosis: a randomized clinical trial

BACKGROUND

To study the effectiveness of an aromatase inhibitor (Anastrozole) associated with levonorgestrel-releasing intrauterine device (LNG-IUD, Mirena®) in the treatment of endometriosis.

METHODS

Prospective, randomized clinical trial.

SETTING

University Hospital (single center). Elegibility criteria: Endometriomas > 3 × 4 cm, CA-125 > 35 U/mL and endometriosis symptoms.

PATIENTS

Thirty-one women randomized to anastrozole + Mirena® + Conservative Surgery(CS) (n = 8), anastrozole + Mirena® + transvaginal ultrasound-guided puncture-aspiration (TUGPA) (n = 7), Mirena® + CS (n = 9), or Mirena® + TUGPA (n = 7).

INTERVENTIONS

Anastrozole 1 mg/day and/or only Mirena® for 6 months; CS (ovarian and fertility-sparing) or TUGPA of endometriomas one month after starting medical treatment.

MAIN OUTCOME MEASURES

Visual analogic scale for symptoms, CA-125 levels, ultrasound findings of endometriomas and recurrences.

RESULTS

A significant improvement in symptoms during the treatment (difference of 43%, 95% CI 29.9-56.2) occurred, which was maintained at 1 and 2 years. It was more significant in patients including anastrozole in their treatment (51%, 95% CI 33.3-68.7). For CA-125, the most significant decrease was observed in patients not taking anastrozole (73.8%, 95% CI 64.2-83.4 vs. 53.8%, 95% CI 25.7-81.6 under Mirena® + anastrozole). After CS for endometriosis, a reduction of ultrasound findings of endometriomas and long-term recurrence occurred, with or without anastrozole. At 4.2 ± 1.7 years (95% CI 3.57-4.85), 88% of the patients who underwent CS were asymptomatic, without medication or reoperation, compared to only 21% if TUGPA was performed, with or without anastrozole (p = 0.019).

CONCLUSIONS

Dosing anastrozole for 6 months, starting one month before CS of endometriosis, reduces significantly the painful symptoms and delays recurrence, but has no other significant advantages over the single insertion of LNG-IUD (Mirena®) during the same time. Anastrozole and/or only Mirena® associated with TUGPA are not effective.

TRIAL REGISTRATION

Eudra CT System of the European Medicines Agency (London, 29-Sept-2008) Nº EudraCT: 2008-005744-17 (07/11/2008). Date of enrolment of first patient: 15/01/2009.

Aromatase inhibitors for the treatment of endometriosis: a systematic review about efficacy, safety and early clinical development

INTRODUCTION

Pharmacotherapy has a key role in endometriosis treatment and management, however, a significant proportion of patients have only intermittent or limited benefits with current treatment options. Therefore, novel therapeutic approaches are necessary.

AREAS COVERED

This systematic review provides an overview of the efficacy and safety of aromatase inhibitors (AIs) as monotherapies and combination therapies for endometriosis. A systematic literature search was performed from January 1990 to April 2020 in the electronic database MEDLINE, EMBASE, The Cochrane Library, and Web of Science.

EXPERT OPINION

Based on the critical role of estrogens and the rate-limiting step in the production of the estrogens represented by the aromatase enzyme, AIs are a potential therapeutic option for women affected by endometriosis. Nevertheless, further research is needed to clarify the efficacy of AIs in this setting. Adverse effects need to be investigated to clarify the preventive role of add-back therapy. On that basis, AIs should be adopted only as second-line therapy in patients who are refractory to standard treatments in the setting of scientific research. Further studies should define best dosages, appropriate add-back therapies, administration routes, treatment length, and which patients may benefit more from AIs.

Novel drug delivery methods for improving efficacy of endometriosis treatments

INTRODUCTION

Pharmacotherapy has a key role in the management of endometriosis. However, a significant proportion of patients gains only intermittent or limited benefits. In this regard, alternative and novel drug delivery methods are of paramount importance to improve efficacy and compliance of available treatments and develop alternative medical approaches.

AREAS COVERED

This review aims to provide the reader with a complete overview of available evidence about alternative and novel drug delivery methods for endometriosis pharmacotherapy and highlight new research lines.

EXPERT OPINION

Progestins and estroprogestins, which represent the first-line therapy, are already available in different formulations, being employed for contraception. Nevertheless, evidence on their adoption is still limited for some drug delivery methods, such as vaginal rings, patches, and subcutaneous implants. Further research is needed to define better their clinical utility in patients with endometriosis. Nanotechnologies have been investigated as novel drug delivery methods able to target the drug at the disease level. However, data are very limited and preliminary, and further research is needed to consider a possible clinical application in endometriosis.

Pregnancy rates from intrauterine insemination are equivalent following 1- versus 5-day letrozole administration for ovulation induction: a retrospective study

Objective

To compare the efficacy of single-dose letrozole (25 mg) with a 5-day course (5 mg/day) for ovulation induction (OI).

Design

Retrospective cohort study.

Setting

Hospital.

Patients

Patients undergoing first round of OI and intrauterine insemination with letrozole from January 2015 through December 2017.

Interventions

Patients received letrozole as either a single 25 mg dose for 1 day (1D) versus 5 mg daily for 5 days (5D). A secondary analysis was performed on patients also receiving gonadotropins (GND).

Main Outcome Measures

Pregnancy rate (PR) determined by positive human chorionic GND.

Results

There were 847 patients included in the study, 302 in the 1D group and 284 in the 5D group; 261 patients had concurrent GND administration, 162 1D+GND and 99 5D+GND. There was no difference in smoking status, primary versus secondary infertility, or total motile sperm concentration. Comparing 1D with 5D, there was a statistically significant, although not clinically relevant, difference in both age and body mass index (31 vs. 31.8 years; 26.2 vs. 27.4, respectively). Similarly, comparing 1D+GND with 5D+GND, there was statistically significant difference in body mass index (27.19 vs. 29.1). Secondary outcomes included live birth rate (LBR), multiple gestation rate (MG), and miscarriage rate (SAB). There were no differences between 1D and 5D in the primary outcome of PR (14.2% vs. 11.6%), LBR (9.6% vs. 7%), MG (16.2% vs. 13.8%), or SAB (16.22% vs. 13.8%). In looking at the GND groups alone, there was no difference in PR (18.3% vs. 23.8%), LBR (11.72% vs. 17.86%), MG (8.7% vs. 5.56%), or SAB (13.64% vs. 5.56%). There was a significant difference in cycle cancellation rate in the 1D versus 5D groups (3.9% vs. 9.6%); however, this was not seen in the 1D+GND versus 5D+GND groups.

Conclusions

A single-dose protocol with letrozole in an OI/intrauterine insemination cycle may be considered an alternative to standard 5D dosing protocols with the potential for improved compliance and similar reproductive outcomes.

The impact of letrozole administration on oocyte morphology in breast cancer patients undergoing fertility preservation

Objective:

Patients submitted to oncological fertility preservation with letrozole and gonadotropins seem to present a higher rate of immature oocytes and lower fertilization rates in comparison to infertile patients submitted to IVF cycles with gonadotropins. The aim of this study was to evaluate the influence of letrozole on oocyte morphology in patients with breast cancer submitted to fertility preservation.

Methods:

Retrospective analysis performed at a public tertiary hospital in São Paulo, Brazil. The oocytes were retrieved from patients with breast cancer undergoing fertility preservation (n=69), and from infertile women undergoing in vitro fertilization (n=92). We evaluated 750 oocytes obtained from breast cancer patients submitted to ovarian stimulation with letrozole and gonadotropins, and 699 oocytes from patients without breast cancer submitted to ovarian stimulation for in vitro fertilization with gonadotropins only due to male factor infertility. The mature oocytes retrieved were analyzed for the presence of refractile bodies, ooplasm color and regularity, central granulation degree, cortical granules, zona pellucida staining and regularity, perivitelline space, presence of vacuoles or abnormal smooth-surfaced endoplasmic reticle and oocyte retraction.

Results:

There was a higher incidence of alterations in oocyte morphology in the letrozole group when compared to the control group: increased perivitelline space (p=0.007), irregular zona pellucida (p<0.001), refractile bodies (p<0.001), dark ooplasm (p<0.001), granular ooplasm (p<0.001), irregular ooplasm (p<0.001) and dense central granulation (p<0.001).

Conclusion:

Letrozole is a risk factor for worse oocyte morphology. However, the clinical impact of ovarian stimulation protocol with combined use of gonadotropins and letrozole for fertility preservation remains unclear in this setting. These data underline the importance of establishing the predictive potential of morphological dimorphisms of human oocytes in IVF outcomes.

Endometriosis

Pelvic endometriosis is a complex syndrome characterized by an estrogen-dependent chronic inflammatory process that affects primarily pelvic tissues, including the ovaries. It is caused when shed endometrial tissue travels retrograde into the lower abdominal cavity. Endometriosis is the most common cause of chronic pelvic pain in women and is associated with infertility. The underlying pathologic mechanisms in the intracavitary endometrium and extrauterine endometriotic tissue involve defectively programmed endometrial mesenchymal progenitor/stem cells. Although endometriotic stromal cells, which compose the bulk of endometriotic lesions, do not carry somatic mutations, they demonstrate specific epigenetic abnormalities that alter expression of key transcription factors. For example, GATA-binding factor-6 overexpression transforms an endometrial stromal cell to an endometriotic phenotype, and steroidogenic factor-1 overexpression causes excessive production of estrogen, which drives inflammation via pathologically high levels of estrogen receptor-β. Progesterone receptor deficiency causes progesterone resistance. Populations of endometrial and endometriotic epithelial cells also harbor multiple cancer driver mutations, such as KRAS, which may be associated with the establishment of pelvic endometriosis or ovarian cancer. It is not known how interactions between epigenomically defective stromal cells and the mutated genes in epithelial cells contribute to the pathogenesis of endometriosis. Endometriosis-associated pelvic pain is managed by suppression of ovulatory menses and estrogen production, cyclooxygenase inhibitors, and surgical removal of pelvic lesions, and in vitro fertilization is frequently used to overcome infertility. Although novel targeted treatments are becoming available, as endometriosis pathophysiology is better understood, preventive approaches such as long-term ovulation suppression may play a critical role in the future.

Alternative Oral Agents in Prophylaxis and Therapy of Uterine Fibroids-An Up-to-Date Review

Uterine fibroids (UFs) are the most common tumors of the female genital tract. The effect of UFs on the quality of life and the overall cost of treatment are significant issues worldwide. Tumor size and location are the two specific factors which influence the occurrence of symptoms, the need for, and method of, treatment (some tumors require surgery while some can be treated with selected drugs). Primary prevention and treatment of early UF disease are worthy goals that might have a great impact on health care systems. Several treatments and prophylactic methods can be used in this endeavor. This publication presents current data about lesser-known substances which may have a beneficial effect on the treatment or prophylaxis of UFs and can be administered orally, serving as an alternative to (or complement of) surgery or selective progesterone receptor modulators (SPRMs). Early prevention and treatment of UFs in women from high-risk groups should be our priority. Innovative forms of UF management are under intensive investigation and may be promising options in the near future. Many of them evaluated vitamin D, paricalcitol, epigallocatechin gallate (EGCG), elagolix, aromatase inhibitors (AIs), and cabergoline and deemed them to be safe and effective. The next step in such projects should be properly constructed randomized control trials (RCTs), carried out by successive phases.

Role of Transforming Growth Factor β in Uterine Fibroid Biology

Uterine fibroids (UFs) are benign tumors of the female genital tract made of the smooth muscle of the uterus. UF growth depends mostly on the influence of the steroid hormones and selected growth factors. Transforming growth factor β (TGF-βs) is a polypeptide that consists of three isoforms: TGF-β1, TGF-β2, and TGF-β3. At present, TGF-β is considered to be one of the key factors in the pathophysiology of UFs. It plays a major role in cellular migration within the tumor, stimulates tumor growth, and enhances tumor metabolism. As a consequence of various dependencies, the synthesis and release of TGF-β in a UF tumor is increased, which results in excessive extracellular matrix production and storage. High concentrations or overexpression of TGF-β mediators may be responsible for clinically symptomatic UFs. The aim of this review was to check the available evidence for the influence of the TGF-β family on UF biology. We conducted their search in PubMed of the National Library of Medicine with the use of the following selected keywords: “uterine fibroid”, “leiomyoma”, and “transforming growth factor β”. After reviewing the titles and abstracts, more than 115 full articles were evaluated. We focused on the TGF-β-related molecular aspects and their influence on the most common symptoms that are associated with UFs. Also, we described how the available data might implicate the current medical management of UFs.

Utilization of gynecologic services in women with breast cancer receiving hormonal therapy

BACKGROUND

The selective estrogen receptor modulator tamoxifen is now widely used for the treatment and prevention of breast cancer. Tamoxifen use has been associated with a variety of gynecologic problems. Despite the frequency with which hormonal therapy is used for the treatment of breast cancer, limited population-level data are available to describe the occurrence of gynecologic conditions and the use of surveillance testing in women receiving tamoxifen and aromatase inhibitors.

OBJECTIVE

We performed a population-based analysis among women with breast cancer receiving hormonal therapy with tamoxifen, a drug commonly used in premenopausal and sometimes postmenopausal women, to determine the frequency of gynecologic abnormalities and use of diagnostic and surveillance testing. We compared these findings to women treated with aromatase inhibitors, agents commonly used in postmenopausal women.

STUDY DESIGN

The MarketScan database was used to identify women diagnosed with breast cancer from 2009 through 2013 who underwent mastectomy or lumpectomy. Women receiving tamoxifen (age <50 vs ≥50 years) were compared to women ≥50 years of age treated with aromatase inhibitors. We examined the occurrence of gynecologic symptoms and diseases (vaginal bleeding, endometrial polyps, endometrial hyperplasia, and endometrial cancer) and gynecologic procedures and interventions (transvaginal ultrasound, endometrial biopsy, hysteroscopy/dilation and curettage, and hysterectomy). Time-dependent analyses were performed to examine symptoms and testing.

RESULTS

A total of 75,170 women, including 15,735 (20.9%) age <50 years treated with tamoxifen, 13,827 (18.4%) age ≥50 years treated with tamoxifen, and 45,608 (60.7%) age ≥50 years treated with aromatase inhibitors were identified. The cumulative incidence of any gynecologic symptom or pathologic diagnosis during the study period was 20.2%, 12.3%, and 3.5%, respectively (P < .001), while the cumulative incidence of any gynecologic procedure or intervention during the study period was 34.2%, 20.9%, and 9.0%, respectively (P < .0001). Among women without symptoms or pathology, interventions were performed in 20.0%, 11.0%, and 6.8%, respectively (P < .0001).

CONCLUSION

Compared to women taking aromatase inhibitors, gynecologic symptoms, procedures, and pathology are higher for both premenopausal and postmenopausal women with breast cancer on tamoxifen. Increased efforts to curb use of gynecologic interventions in asymptomatic women are needed.

Fetal safety profile of aromatase inhibitors: Animal data

Aromatase inhibitors (AIs) are a class of drugs that act by blocking the production of estrogens from androgens. The current review concentrates on the prenatal developmental toxicity of AIs in experimental models. Available data indicate that AIs may affect pregnancy at human therapeutic or lower doses. The window of vulnerability to AIs is not limited to organogenesis, but also includes the preimplantation stage and fetal periods. Decreased embryo/fetal survival was the prominent treatment-related effect. Morphological anomalies noted in fetuses exposed to AIs included skeletal anomalies, abnormal head morphology, increased ano-genital distance in female fetuses, and minor urinary tract system anomalies. Placental enlargement was consistently reported in rats and non-human primates after maternal treatment with several AIs. In conclusion, data from basic scientific research suggest that low intensity exposure to AIs applied during a wide gestational window can profoundly affect prenatal development.