A historical perspective of aromatase inhibitors for ovulation induction

Evaluation of birth outcomes, congenital anomalies and neonatal complications of singletons born to infertile women treated with letrozole: A retrospective cohort study

At present, safety of letrozole administration as an ovulation-inducing drug still remains controversial. Investigation of the safety of letrozole use for the induction of ovulation in the Chinese population is scant. The present study aimed to fill this gap. Data concerning mothers using letrozole and birth outcomes of their singleton offspring were collected as the letrozole group (n=194), equivalent data from mothers using non-letrozole drugs and their singleton offspring were included as the non-letrozole group (control, n=154). Birth outcomes, congenital anomalies and neonatal complications were compared and analyzed between the two groups. Univariate analysis, Spearman's rank correlation analysis and the logistic regression model were utilized. For birth outcomes, the percentage of caesarean section deliveries in the letrozole group was lower than the non-letrozole group (43.8 vs. 56.4%, P=0.019). For congenital anomalies, no significant difference was found between the two groups (all P>0.05). The statistical P-value for the correlation between the maternal use of letrozole and neonatal complications was marginal (P=0.051). Results from the logistic regression analysis confirmed that maternal use of letrozole was not a significant contributor for neonatal complications, independent of statistical adjustment [crude odds ratio (OR), 1.436; 95% confidence interval (CI), 0.803-2.569; P=0.223 vs. adjusted OR, 1.406; 95% CI, 0.748-2.643; P=0.290). The results of the present study suggested that maternal use of letrozole for ovulation induction does not associate with poorer birth outcomes or increased risk of congenital anomalies and neonatal complications.

Assisted Reproductive Technology and Disease Management in Infertile Women with Multiple Sclerosis

Multiple sclerosis (MS) predominantly affects women of fertile age. Various aspects of MS could impact on fertility, such as sexual dysfunction, endocrine alterations, autoimmune imbalances, and disease-modifying therapies (DMTs). The proportion of women with MS (wMS) requesting infertility management and assisted reproductive technology (ART) is increasing over time. In this review, we report on data regarding ART in wMS and address safety issues. We also discuss the clinical aspects to consider when planning a course of treatment for infertility, and provide updated recommendations to guide neurologists in the management of wMS undergoing ART, with the goal of reducing the risk of disease activation after this procedure. According to most studies, there is an increase in relapse rate and magnetic resonance imaging activity after ART. Therefore, to reduce the risk of relapse, ART should be considered in wMS with stable disease. In wMS, especially those with high disease activity, fertility issues should be discussed early as the choice of DMT, and fertility preservation strategies might be proposed in selected cases to ensure both disease control and a safe pregnancy. For patients with stable disease taking DMTs compatible with pregnancy, treatment should not be interrupted before ART. If the ongoing therapy is contraindicated in pregnancy, then it should be switched to a compatible therapy. Prior to beginning fertility treatments in wMS, it would be reasonable to assess vitamin D serum levels, thyroid function and its antibody serum levels; start folic acid supplementation; and ensure smoking and alcohol cessation, adequate sleep, and food hygiene. Cervico-vaginal swabs for Ureaplasma urealyticum, Mycoplasma hominis, and Chlamydia trachomatis, as well as serology for viral hepatitis, HIV, syphilis, and cytomegalovirus, should be performed. Steroids could be administered under specific indications. Although the available data do not clearly show a definite raised relapse risk associated with a specific ART protocol, it seems reasonably safe to prefer the use of gonadotropin-releasing hormone (GnRH) antagonists for ovarian stimulation. Close clinical and radiological monitoring is reasonably recommended, particularly after hormonal stimulation and in case of pregnancy failure.

Improved Pregnancy Outcomes and Endometrial Receptivity by Thawed Frozen Embryo Transfer in Mildly Stimulated Cycles with Letrozole Combined with Estrogen in Women with Unresponsive Thin Endometrium Compared to Standard Endometrial Preparation with Estrogen Alone: A Retrospective Study

Context

Infertile women undergoing frozen embryo transfer (FET) cycles may not show optimal endometrial growth with estrogens alone.

Aim

To evaluate clinical effect of mild stimulation with letrozole and estrogens on endometrial growth in comparison to standard endometrial preparation with oral and topical estrogens in infertile women with unresponsive thin endometrium undergoing FET.

Settings and design

Retrospective observational case-control study.

Material and methods

Forty women unresponsive to first AC-FET cycle were given mild stimulation with letrozole and estrogens as second LE-FET cycle for endometrial preparation (LE-FET study group) and compared with 40 historical controls who had received two cycles of AC-FET (AC-FET control group). Responses were assessed by optimal endometrial thickness (≥ 7 mm) and clinical pregnancy.

Statistical analysis

Descriptive statistics were elaborated by mean ± SD and percentages. Results were expressed by mean ± SD, unpaired t test for difference in endometrial thickness, chi square and Fisher exact test to compare the difference in pregnancy among both groups.

Results

Mean endometrial thickness was significantly increased in LE-FET study group (6.68 ± 2.09 mm) versus AC-FET control group (5.35 ± 1.90 mm). Higher clinical pregnancy rate was noted in study group as compared to control group (35% versus 12.5%).

Conclusion

This study suggests that letrozole with estradiol (LE-FET) compared to estradiol alone (AC-FET) for second cycle significantly increased endometrial thickness and improved clinical pregnancy rates in women with unresponsive thin endometrium after first AC-FET cycle with estradiol alone. Addition of letrozole to estrogen upfront for FET cycles may enhance endometrial receptivity and might improve pregnancy outcomes.

A Review on the Use of Letrozole in Female and Male Infertility

Infertility in developing countries is a distinct and complex problem that disproportionately affects women. Though not a physically restraining disease, it causes a huge social burden on the emotional, financial, and psychosocial quotients of those who suffer from it. Assisted reproductive procedures are frequently used to treat infertility. Years ago, the emergence of ovulation induction represented a significant advancement in treating female infertility. Letrozole, an aromatase inhibitor, is a potential therapy for ovulation induction. Numerous clinical conditions, including anovulatory infertility, polycystic ovarian syndrome, unexplained infertility, and early stages of endometriosis-related infertility, as well as many with improved live birth rates, have been proven to benefit from letrozole treatment. Letrozole is a superior alternative to the widely utilized ovulation induction with clomiphene citrate. While clomiphene citrate has certain limitations, letrozole successfully overcomes these limitations because of its lack of prolonged anti-estrogenic activity, short half-life, and lack of estrogen receptor activation. In most cases, this results in mono-follicular development and excellent live birth rates. According to the most recent research, letrozole can be used as the first-line therapy to treat infertility caused by polycystic ovarian syndrome and other causes. Letrozole is also emerging as a possible treatment for male infertility of unknown cause, proving to be an effective way of influencing hormonal profiles and increasing various seminal parameters such as sperm motility and concentration, as it inhibits aromatization affecting the feedback mechanism to the hypothalamus. This review focuses on our current knowledge of the uses of letrozole for female and male infertility, its mechanisms, and its benefits.

Perinatal outcomes and congenital anomalies associated with letrozole and natural cycles in single fresh cleaved embryo transfers: A single-center, 10-year cohort study

Objective

To investigate and compare the safety of letrozole and natural cycles in fresh early embryo transfers.

Design

A retrospective cohort study.

Setting

A large fertility treatment center.

Patient(s)

Women who underwent natural and letrozole cycles during fresh early embryo transfer at Kato Ladies Clinic between January 2008 and December 2017.

Intervention(s)

None.

Main Outcome measure(s)

Perinatal complications and congenital anomalies.

Result(s)

No significant differences were observed in pregnancy complications, gestational age, birth weight, small for gestational age, large for gestational age, and congenital anomalies between the the women who underwent natural and letrozole cycles.

Conclusion(s)

The perinatal outcomes and congenital anomaly rates associated with letrozole and natural cycles in fresh early embryo transfers were comparable. Therefore, our data support the safe use of letrozole in fresh early embryo transfers in assisted reproductive technology.

Estrogen Biosynthesis and Signal Transduction in Ovarian Disease

Estrogen mainly binds to estrogen receptors (ERs) to regulate menstrual cycles and reproduction. The expression of ERalpha (ERα), ERbeta (ERβ), and G-protein-coupled estrogen receptor (GPER) mRNA could be detected in ovary, suggesting that they play an important role in estrogen signal transduction in ovary. And many studies have revealed that abnormal expression of estrogen and its receptors is closely related to ovarian disease or malignant tumors. With the continuous development and research of animal models, tissue-specific roles of both ERα and ERβ have been demonstrated in animals, which enable people to have a deeper understanding of the potential role of ER in regulating female reproductive diseases. Nevertheless, our current understanding of ERs expression and function in ovarian disease is, however, incomplete. To elucidate the biological mechanism behind ERs in the ovary, this review will focus on the role of ERα and ERβ in polycystic ovary syndrome (PCOS), ovarian cancer and premature ovarian failure (POF) and discuss the major challenges of existing therapies to provide a reference for the treatment of estrogen target tissue ovarian diseases.

Prevalence of polycystic ovarian syndrome, phenotypes and their ovulation response to sequential letrozole dose escalation among infertile women at a tertiary care centre in Southern India

Background:

Women with polycystic ovarian syndrome (PCOS) often have anovulatory infertility requiring ovulation induction with letrozole.

Aims:

This study aimed to determine the prevalence and phenotypic categorisation of infertile PCOS women and to assess ovulatory response and pregnancy rates of PCOS phenotypes with sequential letrozole dose escalation.

Study Setting and Design:

This was a prospective observational study.

Materials and Methods:

One hundred seventy-five infertile PCOS women were enrolled. One hundred fifty-six women received ovulation induction as per the protocol with sequential letrozole dose escalation in each subsequent cycle (2.5 mg, 5 mg and 7.5 mg). Responses were assessed by ovulation and/or pregnancy.

Statistical Analysis Used:

Descriptive statistics were elaborated by means, medians, frequencies and percentages. Group comparisons and linear correlation between two continuous variables were done using appropriate statistical tests.

Results:

Eighty-seven (49.7%) women were Phenotype A; 11 (6.3%) were Phenotype B; 20 (11.4%) were Phenotype C and 57 (32.6%) were Phenotype D in our study. After excluding the lost to follow up participants in each induction cycle, 33.3% (2.5 mg dose); 62.8% (5 mg dose) and 78.9% (7.5 mg dose) women responded to letrozole. A significant increase in ovulation to escalating letrozole doses was noted (Phenotype A: 35.1% to 2.5 mg, 53.7% to 5 mg and 72.7% to 7.5 mg; Phenotype B: 30% to 2.5 mg and 80% to 5 mg; Phenotype C: 35.3% to 2.5 mg and 87.5% to 5 mg and Phenotype D: 30.8% to 2.5 mg, 65.6% to 5 mg and 87.5% to 7.5 mg). Fifty-six of 156 (35.9%) infertile PCOS women achieved pregnancy; increase in pregnancy rates with escalated doses of letrozole was noted.

Conclusion:

All PCOS phenotypes show a similar response to escalating doses of letrozole. The role of phenotypic sub-categorisation for variable response to letrozole as an ovulation-inducing agent is uncertain.

Effect and Management of Excess Weight in the Context of Fertility-Sparing Treatments in Patients With Atypical Endometrial Hyperplasia and Endometrial Cancer: Eight-Year Experience of 227 Cases

Objective

To investigate the oncologic and reproductive outcomes of fertility-sparing treatments (FSTs) in atypical endometrial hyperplasia (AEH) and endometrial cancer (EC) patients with excess weight (EW).

Methods

This retrospective study comprised patients with AEH or EC who achieved a complete response (CR) after FST from 2010 to 2018. The clinical characteristics, oncological and reproductive outcomes were compared between the excess weight (EW) group (body mass index (BMI)≥25 kg/m²) and normal weight (NW) group (BMI<25 kg/m²). The risk factors associated with recurrence and unsuccessful pregnancy in patients with EW were analyzed.

Results

Overall, 227 patients were enrolled, including 139 (61.2%) in EW group and 88 (38.8%) in NW group. In patients with EW, the pregnancy rate, the live birth rate and the relapse rate were 29.8%, 23.4%, and 30.9%, respectively. In patients with NW, these rates were 61.1%, 47.2%, and 31.8%, respectively. No significant differences were observed in the time to remission (P=0.865) and disease-free survival (DFS) (P=0.750). Patients in NW group achieved a better pregnancy rate than patients in the EW group (P=0.034). The patients with EW using ovulation induction to increase fertility tended to have a shorter time to pregnancy (P=0.042). However, no significant risk factors associated with unsuccessful pregnancy were identified after the multivariate analysis. In terms of DFS, the combination of gonadotropin-releasing hormone agonist (GnRH-a) and LNG-IUD was better for patients with EW than GnRH-a or oral progestin therapy alone (P=0.044, adjusted hazard ratio (HR)=0.432, 95% confidence interval (CI): 0.152-1.229), especially for patients with EW diagnosed with EC (P=0.032).

Conclusion

FSTs for overweight and obese patients should be more individualized. GnRH-a and/or LNG-IUD may be options prior to FSTs in patients with EW. Further prospective studies are needed.

Impact of letrozole co-treatment during ovarian stimulation with gonadotrophins for IVF: a multicentre, randomized, double-blinded placebo-controlled trial

STUDY QUESTION

Does letrozole co-treatment during ovarian stimulation with gonadotrophins for IVF reduce the proportion of women with premature progesterone levels above 1.5 ng/ml at the time of triggering final oocyte maturation?

SUMMARY ANSWER

The proportion of women with premature progesterone above 1.5 ng/ml was not significantly affected by letrozole co-treatment.

WHAT IS KNOWN ALREADY

IVF creates multiple follicles with supraphysiological levels of sex steroids interrupting the endocrine milieu and affects the window of implantation. Letrozole is an effective aromatase inhibitor, normalizing serum oestradiol, thereby ameliorating some of the detrimental effects of IVF treatment.

STUDY DESIGN, SIZE, DURATION

A randomized, double-blinded placebo-controlled trial investigated letrozole intervention during stimulation for IVF with FSH. The trial was conducted at four fertility clinics at University Hospitals in Denmark from August 2016 to November 2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A cohort of 129 women with expected normal ovarian reserve (anti-Müllerian hormone 8-32 nmol/l) completed an IVF cycle with fresh embryo transfer and received co-treatment with either 5 mg/day letrozole (n = 67) or placebo (n = 62), along with the FSH. Progesterone, oestradiol, FSH, LH and androgens were analysed in repeated serum samples collected from the start of the stimulation to the mid-luteal phase. In addition, the effect of letrozole on reproductive outcomes, total FSH consumption and adverse events were assessed.

MAIN RESULTS AND THE ROLE OF CHANCE

The proportion of women with premature progesterone >1.5 ng/ml was similar (6% vs 0% (OR 0.0, 95% CI [0.0; 1.6], P = 0.12) in the letrozole versus placebo groups, respectively), whereas the proportion of women with mid-luteal progesterone >30 ng/ml was significantly increased in the letrozole group: (59% vs 31% (OR 3.3, 95% CI [1.4; 7.1], P = 0.005)). Letrozole versus placebo decreased oestradiol levels on the ovulation trigger day by 68% (95% CI [60%; 75%], P < 0.0001). Other hormonal profiles, measured as AUC, showed the following results. The increase in LH in the letrozole group versus placebo group was 38% (95% CI [21%; 58%], P < 0.0001) and 34% (95% CI [11%; 61%], P = 0.006) in the follicular and luteal phases, respectively. In the letrozole group versus placebo group, testosterone increased by 79% (95% CI [55%; 105%], P < 0.0001) and 49% (95% CI [30%; 72%], P < 0.0001) in the follicular and luteal phases, respectively. In the letrozole group versus placebo group, the increase in androstenedione was by 85% (95% CI [59%; 114%], P < 0.0001) and 69% (95% CI [48%; 94%], P < 0.0001) in the follicular and luteal phases, respectively. The ongoing pregnancy rate was similar between the letrozole and placebo groups (31% vs 39% (risk-difference of 8%, 95% CI [-25%; 11%], P = 0.55)). No serious adverse reactions were recorded in either group. The total duration of exogenous FSH stimulation was 1 day shorter in the intervention group, significantly reducing total FSH consumption (mean difference -100 IU, 95% CI [-192; -21], P = 0.03).

LIMITATIONS, REASONS FOR CAUTION

Late follicular progesterone samples were collected on the day before and day of ovulation triggering for patient logistic considerations, and the recently emerged knowledge about diurnal variation of progesterone was not taken into account. The study was powered to detect hormonal variations but not differences in pregnancy outcomes.

WIDER IMPLICATIONS OF THE FINDINGS

Although the use of letrozole has no effect on the primary outcome, the number of women with a premature increase in progesterone on the day of ovulation triggering, the increased progesterone in the mid-luteal phase due to letrozole may contribute to optimizing the luteal phase endocrinology. The effect of letrozole on increasing androgens and reducing FSH consumption may be used in poor responders. However, the effect of letrozole on implantation and ongoing pregnancy rates should be evaluated in a meta-analysis or larger randomized controlled trial (RCT).

STUDY FUNDING/COMPETING INTEREST(S)

Funding was received from EU Interreg for ReproUnion and Ferring Pharmaceuticals, and Roche Diagnostics contributed with assays. N.S.M. and A.P. have received grants from Ferring, Merck Serono, Anecova and Gedeon Richter, and/or personal fees from IBSA, Vivoplex, ArtPred and SPD, outside the submitted work. The remaining authors have no competing interests.

TRIAL REGISTRATION NUMBERS

NCT02939898 and NCT02946684.

TRIAL REGISTRATION DATE

15 August 2016.

DATE OF FIRST PATIENT’S ENROLMENT

22 August 2016.

Mechanism of quercetin on the improvement of ovulation disorder and regulation of ovarian CNP/NPR2 in PCOS model rats

PURPOSE

To investigate the effects of quercetin on ovulation disorder and expression of androgen receptor (AR) and C-type natriuretic peptide (CNP) / Natriuretic Peptide Receptor 2 (NPR2) in dehydroepiandrosterone (DHEA)-induced polycystic ovary syndrome (PCOS) rat model.

METHODS

DHEA was used to construct the PCOS rat model. After intervention with quercetin, metformin, and AR, the estrous cycle, ovarian and uterine weight of rats were measured. The morphological changes of ovarian and uterine were detected by hematoxylin-eosin staining (HE staining). Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured by Enzyme linked immunosorbent assay (ELISA). Immunohistochemical detection of interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-alpha (TNF-α), B-cell lymphoma-2 (BCL-2), BCL2-Associated X (Bax) and AR expression in ovarian. Determination of the expression of CNP and NPR2 mRNA by qRT-PCR. Chromatin immunocoprecipitation (ChIP) was used to detect the ability of AR to bind to CNP or NPR2 promoter.

RESULTS

The results showed that quercetin could significantly reduce the expression of Testosterone (T) , Estradiol (E₂) , LH, Bax, IL-1β, IL-6 and TNF-α, increase the expression of FSH and Bcl-2, inhibit the expression of AR, regulate the expression of CNP / NPR2 gene and protein by affecting the combination of AR with the specific sequence of CNP and NPR2 gene promoters, restore the maturation of oocyte and ovulation.

CONCLUSION

The results suggest that quercetin can alleviate the hormone, metabolic and ovulatory aberrations caused by PCOS, and provide experimental basis for the clinical application of quercetin in PCOS.

Ovarian stimulation drugs alter the metabolite content of the growing follicle: in vivo spectroscopic evaluation of follicle fluid

Objective

To determine and compare metabolite content using magnetic resonance spectroscopy (MRS) of growing follicles in patients with polycystic ovary syndrome (PCOS) receiving recombinant follicle stimulating hormone (rFSH), clomiphene citrate (CC) or aromatase inhibitor (AI) for ovarian stimulation.

Material and Methods

Thirty patients diagnosed with PCOS and infertility and scheduled for ovarian stimulation were divided by therapy, rFSH/CC/AI, into three equal groups. Five fertile cases were designated as the control group. When the follicle diameters reached 16-18 mm in each group, patients underwent MRS and the metabolite content of a dominant follicle was analyzed. N-acetylaspartate, lactate (Lac), creatine (Cr), and choline (Cho) metabolite levels in parts per million were measured in the spectra.

Results

A ~three-fold decrease in dominant follicle Cho content was found in patients receiving CC compared to control subjects. Similarly, the dominant follicle Cho intensities of patients given rFSH and AI were noted to be significantly higher than those who received CC. Only dominant follicle Lac levels of the patients who received CC were found to be significantly higher than the other groups. Cr peak intensities of patients receiving CC were found to be approximately three times less than control subjects. Cr signal intensity was significantly higher in patients receiving rFSH or AI than in patients receiving CC. While two patients became pregnant in the CC group, three patients in the AI group and five patients in the rFSH group became pregnant. The main metabolites detected in patients who conceived in each group were Cho and Cr. In cases who could not conceive, while Lac and lipid signals increased, Cho and Cr signals decreased.

Conclusion

Unlike CC, ovarian stimulation with rFSH or AI does not alter dominant follicle metabolite content. The developmental capacity of a growing egg may be determined non-invasively with MRS.

Effects of letrozole or tamoxifen coadministered with a standard stimulation protocol on fertility preservation among breast cancer patients

PURPOSE

To assess the effects of letrozole or tamoxifen coadministration on fertility preservation treatment outcomes.

METHODS

Retrospective cohort study of 118 breast cancer patients undergoing fertility preservation treatment between 2008 and 2018. Patients who received letrozole (n = 36) or tamoxifen (n = 30) were compared to controls (n = 52) who underwent standard ovarian stimulation protocols. The primary outcome measures included the number of retrieved oocytes, mature oocytes (MII), fertilization, and top-quality embryo rates. The secondary outcome measures included duration of stimulation, gonadotropin dose and peak estradiol level.

RESULTS

The number of oocytes retrieved, MII oocytes, fertilization rate, duration of stimulation, or gonadotropin dose were similar in the letrozole and tamoxifen groups, compared to controls. Top-quality embryo rate was lower in the tamoxifen group compared to controls (25% vs 39.4%, respectively, P = 0.034). The abnormal fertilization rate was higher in the letrozole group compared to controls (7.8% vs 3.60%, respectively, P = 0.015). A stepwise logistic regression analysis revealed that letrozole and peak estradiol were significantly associated with abnormal fertilization (OR 11.94; 95% CI 2.35-60.4, P = 0.003 for letrozole and OR 1.075; 95% CI 1.024-1.12, P = 0.004 per 100 unit change in estradiol).

CONCLUSIONS

There may be a negative effect of letrozole or tamoxifen on fertilization and embryo quality, in fertility preservation cycles. Further studies are needed to confirm these findings.

Letrozole for Female Infertility

Letrozole, an aromatase inhibitor that blocks estrogen synthesis by inhibiting the final step of the estrogen biosynthetic pathway, has been used in the applications of a wide range of infertility settings. It has been more than 20 years since the initial clinical trial of letrozole for ovulation induction. In light of the accumulating clinical and basic evidence, the efficacy and safety of letrozole have been identified. This mini review focuses on our current knowledge of the applications and mechanisms of letrozole for female infertility and various questions are put forward about how letrozole could be more effectively used.

Antenatal antioxidants to avert autism?

Paternally derived de novo mutations (DNMs) caused by oxidative stress (OS) have been implicated in the development of autism spectrum disorders (ASDs). Whether preconception antioxidant supplementation can reduce the incidence of ASDs by reducing OS is an area of uncertainty and potentially important future scientific investigation.

Pregnancy Outcomes Following Letrozole Use in Frozen-thawed Embryo Transfer Cycles: A Systematic Review and Meta-analysis

While widely used for ovulation induction in assisted reproductive technology, the clinical efficacy of letrozole for endometrial preparation prior to frozen-thawed embryo transfer (FET) cycles remains yet to be elucidated. We performed a meta-analysis to compare pregnancy outcomes after letrozole use with those of other endometrial preparation protocols in patients undergoing FET. PubMed, Scopus, Embase and the Cochrane Library were searched for eligible studies. Clinical pregnancy rate (CPR), live birth rate (LBR) and birth defect rate (BDR) were analysed using odds ratio (OR) and 95% confidence interval (CI). A total of 10 studies representing 75 968 FET cycles were included. Comparable CPR and LBR were observed when comparing letrozole administration with natural cycle (OR 1.24, 95% CI: 0.69 – 2.24; OR 1.18, 95% CI: 0.60 – 2.32), artificial cycle (OR 1.46, 95% CI: 0.87 – 2.44; OR 1.39, 95% CI: 0.77 – 2.52), and artificial cycle with gonadotropin-releasing hormone agonist suppression (OR 1.11, 95% CI: 0.78 – 1.59; OR 1.18, 95% CI: 0.82 – 1.68). Pooled results of the limited studies comparing letrozole with human menopausal gonadotropin demonstrated a similar CPR between groups (OR 1.46, 95% CI: 0.29 – 7.21, two studies), but the letrozole group had a statistically lower LBR (OR 0.67, 95% CI: 0.52 – 0.86, one study). No increased BDR was observed in the letrozole group compared to natural cycles or artificial cycles (OR 0.98, 95% CI: 0.60 – 1.61; OR 1.39, 95% CI; 0.84 – 2.28). This pooled analysis supports the use of letrozole as an efficacious and safe alternative to mainstream regimens for endometrial preparation in FET cycles.

Aromatase inhibitor letrozole: a novel treatment for ectopic pregnancy

OBJECTIVE

To study the use of the aromatase inhibitor letrozole for treatment of ectopic pregnancy compared with methotrexate.

DESIGN

Nonrandomized prospective cohort study.

SETTING

University hospital.

PATIENT(S)

A series of 42 consecutive patients with undisturbed ectopic pregnancy.

INTERVENTION(S)

Counseling on treatment options, including surgical treatment (control group) versus medical treatment with methotrexate (group 1) or letrozole (group 2).

MAIN OUTCOME MEASURE(S)

Primary outcome: complete resolution of ectopic pregnancy determined by serum human chorionic gonadotropin (β-hCG) levels below laboratory immunoassay detection.

SECONDARY OUTCOMES

changes in the biochemical parameter of ovarian reserve, antimüllerian hormone (AMH), and hematologic changes associated with the two medical treatments compared with surgical treatment.

RESULT(S)

Each treatment group included 14 patients, and each patient made her own treatment choice. Complete resolution of ectopic pregnancy occurred in an equal number of patients: 12 out of 14 (86%) in each of the two medical treatment groups. Methotrexate treatment was associated with statistically significantly higher liver enzymes and lower blood platelets count. The decline in β-hCG levels was faster in the letrozole group when compared with the methotrexate group. Three months after treatment, AMH levels were lower in the methotrexate group when compared with the letrozole and the surgery groups. However, the decline in β-hCG and AMH levels was not statistically significant.

CONCLUSION(S)

To our knowledge, this is the first report in the literature on the success of letrozole for the medical treatment of ectopic pregnancy. The promisingly high resolution rate and better safety profile that letrozole has compared with a chemotherapeutic agent such as methotrexate should encourage further studies.

Research and development of a silicone letrozole-releasing device to control reproduction in cattle

Two experiments were conducted to test the effectiveness of a silicone matrix as an intravaginal drug delivery device for letrozole, an aromatase inhibitor used for synchronization protocols in cattle. A wax dip-coat formulation of the intravaginal device used in previous studies was effective in releasing letrozole but was cumbersome to manufacture and deploy, resulting in unwanted variation in drug delivery and circulating concentrations of letrozole. In Experiment 1, a 3 × 3 design was used to test the release kinetics of letrozole from silicone in vitro. Silicone was mixed with 3 different letrozole drug loads (5%, 10%, 15%) and 3 different mineral oil loads (5%, 10%, 15%), and letrozole release into 62.5% ethanol was compared with the wax dip-coat formulation (positive control) by UV spectrophotometry. Letrozole was released from silicone in a dose-dependent manner, with no effect of mineral oil. Release kinetics were then examined in vivo (Experiment 2) in nulliparous beef heifers assigned randomly to six groups (n = 6/group) and given either a large surface area (LSA) with 5% or 15% drug load, a standard surface area (SSA) intravaginal silicone device impregnated with 10% or 15% drug load, a wax dip-coat device (positive control), or a blank device (negative control). Devices were inserted on Day 3 (Day 0 = ovulation) until Day 11. Blood samples were collected at 0, 30 min, 1, 2, 3, 4, 6, 8, 10, 12, and 24 h, and twice daily until Day 11 to determine letrozole plasma concentrations by LC-MS/MS and estradiol plasma concentrations by radioimmunoassay The ovaries were examined once daily from Day 3-13 by ultrasonography to determine follicular and luteal responses to treatment. Letrozole plasma concentrations were higher in heifers given a device with an LSA vs SSA (P < 0.05). Plasma concentrations of estradiol decreased the most in heifers given the 15% LSA device (P = 0.06). The interval between emergence of successive follicular waves was longest (P < 0.05) in the positive control and the 15% LSA groups. As well, the diameter profiles of the dominant follicle and the corpus luteum were largest (P < 0.01) in the positive control and 15% LSA groups. In conclusion, letrozole was released from a silicone matrix in vitro in a dose-dependent manner, and the 15% LSA devices achieved target effects on ovarian function. Results may be used to manufacture a silicone intravaginal device for delivering aromatase inhibitors in a novel synchronization protocol for cattle.

Effects of the Fertility Drugs Clomiphene Citrate and Letrozole on Kiss-1 Expression in Hypothalamic Kiss-1-Expressing Cell Models

Clomiphene citrate (CC) and letrozole stimulate the hypothalamic-pituitary-ovarian axis and are used widely as oral fertility drugs to induce folliculogenesis. We examined whether these drugs increase Kiss-1 expression in hypothalamic cell models. We utilized two hypothalamic cell models, mHypoA-50 and mHypoA-55, which originated from Kiss-1 neurons in the anteroventral periventricular (AVPV) nucleus and arcuate (ARC) nucleus of the mouse hypothalamus, respectively. The cells were stimulated with CC or letrozole, after which Kiss-1 mRNA expression was determined. CC stimulated Kiss-1 gene expression in mHypoA-50 and mHypoA-55 cells. The basal expression of Kiss-1 was significantly increased in the presence of estradiol (E2) in mHypoA-50 cells, and the CC-induced increase in Kiss-1 expression was not observed in the presence of E2 in these cells. In contrast, E2 did not modify the basal expression of Kiss-1 in mHypoA-55 cells, and CC-induced Kiss-1 expression was still observed in the presence of E2. The significant increase in Kiss-1 gene expression in mHypoA-50 and mHypoA-55 cells was blunted in the presence of estrogen receptor antagonists. Aromatase was expressed in mHypoA-50 and mHypoA-55 cells. Letrozole, an aromatase inhibitor, increased Kiss-1 expression in mHypoA-55 ARC cells but not in mHypoA-50 AVPV cells. Although the basal expression of Kiss-1 was increased by E2, letrozole did not modulate Kiss-1 expression in mHypoA-50 cells. Letrozole-induced Kiss-1 gene expression in mHypoA-55 cells was not modulated in the presence of E2. The fertility drugs CC and letrozole modulated Kiss-1 expression in hypothalamic cell models.

Prospective randomized trial comparing efficacy of letrozole step-up protocol with letrozole plus gonadotropins for controlled ovarian stimulation and intrauterine insemination in patients with unexplained infertility

PURPOSE

Empirical treatment options for unexplained infertility treatment include controlled ovarian stimulation (COS) with clomiphene citrate, letrozole or gonadotropins followed by intrauterine insemination (IUI). Achieving consistent multifollicular development with letrozole generally requires addition of gonadotropins. However, the cost and discomfort of injections remains a drawback of this regimen. Therefore, there is a need for evolving newer cost-effective regimens for COS/IUI using orally administered drugs like letrozole.

METHODS

Sixty couples with unexplained infertility (on standard infertility investigations) visiting the infertility clinic at a tertiary centre in North India were randomized into two groups. Group A COS was done by step-up protocol of letrozole from day 2 or 3 of menstrual cycle, starting with 2.5 mg and increased by 2.5 mg per day for next 3 days (2.5 mg, 5 mg, 7.5 mg, 10 mg). Group B COS was done with combination of letrozole and hMG (human menopausal gonadotropin). Starting from day 2 or 3 of menses, tablet letrozole 2.5 mg twice a day was given for 5 days. Intramuscular injection of hMG 150 IU was given every alternate day starting from day 7 and titrated according to the response. HCG was given when leading follicle was 17 mm and IUI done 36 h after HCG.

RESULTS

Twenty-eight couples in letrozole step-up group (group A) and 30 couples in letrozole plus hMG group (group B), completed follow up for 44 and 55 cycles, respectively. Mean numbers of follicle ≥ 16 mm in both groups were comparable: 1.74 (± 0.83) in group A and 1.94 (± 0.68) in group B (p = 0.178). Ovulation rate of 90.9% (40/44) was achieved in group A, whereas it was 100% (55/55) in group B (p = 0.022), although there was no significant difference in clinical pregnancy rate per patient, which was 3/28 (10.7%) in group A versus 5/30 (16.67%) in group B (p = 0.707). The mean (SD) cost of medicines was significantly lower in group A Rs. 345.00 (00) compared to group B Rs. 2148.64 (515.67) [p < 0.0001]. There was one case each of hyperstimulation and multiple pregnancies in group B, while none in group A.

CONCLUSION

It is possible to achieve multifollicular development with use of novel letrozole step-up protocol, even without addition of gonadotropins, at significantly lower cost.

Endocrine and Targeted Therapy for Hormone-Receptor-Positive, HER2-Negative Advanced Breast Cancer: Insights to Sequencing Treatment and Overcoming Resistance Based on Clinical Trials

Background: Advanced hormone-receptor positive HER2 negative breast cancer is a common and a very heterogeneous disease. Hormone therapy is the main first line treatment of choice, given alone or in combination with other agents that have shown to improve patient outcomes, Nevertheless, treatment remains generally palliative rather than curative. Sequencing of such treatment remains challenging, especially with resurgence of variable resistance patterns. Multiple attempts have been made to overcome resistance and improve patient survival, yet resistance remains not very well understood and metastatic cancer remains a disease with dismal prognosis.

Methods: In this paper, we searched pubmed database as well as local and international meetings for all studies discussing advanced and metastatic hormone-receptor-positive, her2-negative breast cancer, hormonal treatment, resistance to hormonal treatment, mechanism of resistance, and means to overcome such resistance.

Conclusion: There does not exist an optimal treatment sequence for hormone-receptor-positive, her2-negative advanced breast cancer. However, after review of literature, a reasonable approach may be starting with tamoxifen, aromatase inhibitors, or fulvestrant in absence of visceral crisis, in addition to ensuring adequate ovarian function suppression in pre/peri-menopausal women. Aromatase inhibitors and fulvestrant seem to be superior. Resistance to such agents is increasing, mostly attributed to genetic and molecular changes. Multiple modalities are addressed to overcome such resistance including use of CKD4/6 inhibitors, mTOR inhibitors and PI3K inhibitors in addition to other agents under study, all with promising results. CDK4/6 inhibitors work best when used in frontline setting. Finally, treatment of breast cancer remains a growing field, and more studies are to be awaited.

Letrozole supplementation during controlled ovarian stimulation in expected high responders: a pilot randomized controlled study

BACKGROUND

Almost all of the previous studies related with co-administration of letrozole in IVF cycles were performed in poor responders and letrozole may reduce the total gonadotropin dose required for ovarian stimulation, and the pregnancy rate did not decrease in poor responders. This study aimed to assess whether high responders co-treatment with letrozole reduced supraphysiological late follicular phase estradiol levels and the incidence of premature progesterone elevated at the end of the follicular phase, thereby impacting positively on endometrial receptivity.

METHODS

A randomized parallel controlled study in a university-affiliated center include 130 high responders between October 2015 and August 2016. The patients were randomized on the first stimulation day of the IVF cycle and from stimulation day 5 receive letrozole (group A) or without letrozole treatment (group B).

RESULTS

Although estradiol levels were significantly lower in the letrozole group (group A) (P < 0.001), progesterone elevation (> 1.5 ng/mL was considered as a rise) on the day of hCG triggering (15.4, 7.7%) was not statistically significant (P = 0.170). RecFSH, the recovery rate of eggs, the high-quality embryo rate, and the thickness of endometrium (P = 0.776) were similar between the letrozole group(group A) and control groups (group B). Clinical pregnancy rates were 53.1% (26/49) and 72.9% (35/48) in the letrozole and control groups, respectively, with a statistical significance (P = 0.043).Live birth rates were 42.9% (21/49) and 62.5% (30/48),showed a marginally significant difference (P = 0.053). The miscarriage rate did not significantly differ between the two groups.

CONCLUSIONS

In this pilot study, letrozole supplementation could not reduce the incidence of premature progesterone rise during the late follicular phase in stimulated in vitro fertilization cycles in expected high responders, producing a harmful effect on the pregnancy outcome.

TRIAL REGISTRATION

China Clinical Trial Registration Center: ChiCTR-IPR-15006211 URL of the trial registry record: http://www.chictr.org.cn/showproj.aspx?proj=10731 . Trial registration date: 8 April, 2015. Date of first patient's enrolment: 5 October, 2015.

Pharmacology of medications used for ovarian stimulation

Medications to stimulate the ovaries may be used to induce ovulation in patients with anovulatory infertility or to hyperstimulate the ovaries in a controlled fashion in ovulatory patients as part of assisted reproductive treatments (ART). The pharmacology of all current major medications used to stimulate ovarian function is reviewed in this article, including letrozole, clomiphene citrate, gonadotropins, and pulsatile gonadotropin releasing hormone (GnRH). Novel potential compounds and adjuvant treatment approaches are also discussed, such as kisspeptin agonists and androgens.

The effects of letrozole and clomiphene citrate on ligands expression of Wnt3, Wnt7a, and Wnt8b in proliferative endometrium of women with Polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) is a common endocrinologic disorder in women of reproductive age characterized by polycystic ovaries, oligo/anovulation, and hyperandrogenism. Not only anovulation but also endometrial dysfunction can reduce fertility in PCOS patients. Wnt pathway is responsible for endometrial proliferation which be strongly regulated by estradiol. To determine the effects of clomiphene citrate (CC) and letrozole, we measured the expression of some main ligands of Wnt/β-catenin signaling including Wnt7a, Wnt3, and Wnt8b in the endometrial samples taken from PCOS women on day 12 of the menses who received 100 mg CC or 5 mg letrozole as well as from women without treatment. Significantly, the mean estrogen and progesterone concentration were lower and higher, respectively, in letrozole than CC. The mean endometrial thickness (ET) was significantly greater in letrozole compared to CC. Assessment of the mRNA and protein expression of Wnt7a, Wnt3, and Wnt8b showed significantly lower expression in CC than the letrozole and control groups. Collectively, letrozole provided a better molecular response in the endometrium of PCOS patients during the proliferative phase, similar to natural cycles, compared to CC. CC decreased the ligands expression of Wnt3, Wnt7a, and Wnt8b, resulting in endometrial dysfunction.

Effects of a single 20 mg dose of letrozole on ovarian function post dominant follicle selection: an exploratory randomized controlled trial

BACKGROUND

Our objective was to explore the impact of a single dose of an aromatase inhibitor (letrozole) administered at defined times of the follicular phase or immediately after ovulation on dominant follicle development, luteogenesis and new follicle wave emergence.

METHODS

A prospective pilot study using a randomized complete block, controlled, open label design was conducted at an academic clinical research center. Forty-five healthy, female volunteers (25.5 ± 0.9 years, BMI 25.0 ± 0.6 kg/m2) who had not taken hormonal contraceptives for a minimum of 2 months were recruited. A 20 mg dose of Letrozole was administered once orally in each of 3 groups when the dominant follicle reached a diameter of 1) 12 mm, 2) 18 mm, 3) the first day following ovulation (post-ovulation), or 4) treatment was withheld (control). Serial ultrasonography and phlebotomy began on day 4 of the menstrual cycle and continued for 1.5 menstrual cycles. Participants recorded menses and daily events in a life events calendar for the duration of the study. Demographic and single point measurements were compared among groups by ANOVA. Changes in hormone concentrations over time were compared among groups by repeated measures ANOVA. Kruskal-Wallis tests were used for non-normally distributed data.

RESULTS

The dominant follicle in all treatment groups ovulated. There were no differences among experimental groups in peak follicle diameter, follicular growth rate, endometrial thickness at ovulation or inter-ovulatory interval. Plasma concentrations of estradiol dropped, while FSH and LH concentrations rose following treatment in all treatment groups. Plasma FSH and LH concentrations were higher in the 18 mm group compared to the 12 mm and post-ovulation groups (P < 0.02).

CONCLUSION

Administration of a single 20 mg dose of Letrozole at the times of the menstrual cycle we examined did not induce dominant follicle regression or failure of corpus luteum formation. Letrozole-induced suppression of estradiol synthesis by the dominant follicle was not detrimental to follicle growth or ovulation following follicle selection, likely due to increased circulating concentrations of FSH and LH resulting from a lack of estradiol-induced suppression of the hypothalamic-pituitary-ovarian axis.

TRIALS REGISTRATION NUMBER

Clinical trials registration number NCT01046578 .

Anastrozole plus leuprorelin in early maturing girls with compromised growth: the "GAIL" study

PURPOSE

Aromatase inhibitors have been used to increase predicted adult height (PAH) in boys but in girls only in McCune-Albright syndrome. We investigated whether anastrozole combined with leuprorelin for up to 2 years is safe and effective in improving PAH in girls with early puberty and compromised growth, compared to leuprorelin alone.

METHODS

The "GAIL" study: girls treated with an aromatase inhibitor and an LHRH analogue, ISRCTN11469487, was a 7-year prospective phase IIa study with parallel design, performed at Athens Medical Center (C-A), and Attikon University Hospital, Athens, Greece (C-B). Forty girls, consecutively referred for early puberty (onset 7.5-9 years) with a PAH <-2 or >1.5 SD lower than their target height (TH), were included. Twenty started on leuprorelin sc/im 0.3 mg/kg/month plus anastrozole 1 mg/d p.o. (group-A, C-A) and 20 on leuprorelin (group-B, C-B) for 2 years or until the age of 10 years. Groups did not differ in age, height, BMI, bone age advancement (BAA), and distance of PAH from TH. Follow-up was at 6, 12, 18, and 24 m.

RESULTS

Reduction in BAA was significantly higher in group-A compared to group-B already by 6 m. Despite the transiently significant decrease in height velocity in group-A, gain in PAH SD was almost double by 12 and 18 m vs group-B and reached the maximum of +1.21 ± 0.45 (7.51 cm) vs +0.31 ± 0.37 (1.92 cm, p = 0.001) in group-B at 24 m. Group-A had no clinical or biochemical hyperandrogenism, unchanged normal bone density, and lumbar spine X-rays.

CONCLUSION

The co-administration of anastrozole with leuprorelin safely improves PAH in girls with compromised growth.

Use of letrozole and clomiphene citrate combined with gonadotropins in clomiphene-resistant infertile women with polycystic ovary syndrome: a prospective study

Background

Gonadotropin has been used to stimulate ovulation in clomiphene-resistant infertile women with polycystic ovary syndrome (PCOS), but it is associated with overstimulated cycles with the development of many follicles. The aim of the study was to evaluate the effectiveness and efficacy of letrozole and clomiphene citrate (CC) combined with human menopausal gonadotropin (HMG) in CC-resistant infertile women with PCOS.

Methods

Ninety-four women received the letrozole + HMG, 90 women received CC + HMG, and 71 women received HMG only. All women received one treatment regimen in one treatment cycle. All patients were given HMG 75 IU on alternate days daily starting on day 3 or day 7 until the day of administration of human chorionic gonadotropin.

Results

The rate of monofollicular development was 80.2% in the letrozole + HMG group, 65.3% in the CC + HMG group, and 54.7% in the HMG-only group (P<0.05 for letrozole + HMG vs the other two groups). The number of developing follicles (≥14 mm follicles) and the cycle cancellation rate due to ovarian hyperresponse were the lowest in the letrozole + HMG group, but the difference was not significant. The ovulation and pregnancy rate were similar among the three protocols. The HMG dose needed and the mean duration of treatment were significantly lower in the letrozole + HMG and CC + HMG groups compared with the HMG-only group.

Conclusion

Letrozole in combination with HMG is an effective protocol for reducing the risks of hyperstimulation for ovarian induction in CC-resistant women with PCOS. This combination may be more appropriate in patients who are particularly sensitive to gonadotropin.

Factors associated with nonresponse to ovulation induction using letrozole among women with World Health Organization group II anovulation

CONTEXT:

Letrozole, a third generation aromatase inhibitor is gaining importance in ovulation induction. Some prefer to use it as a second line agent in women who fail to respond to clomifene citrate. However, our knowledge about the predictors of response to letrozole is limited.

AIMS:

The study was aimed at identifying the factors associated with letrozole resistance among women with World Health Organization (WHO) group II anovulation.

SUBJECTS AND METHODS:

Study was conducted at the infertility clinic at a tertiary care hospital in Sri Lanka. A case–control study design was used and included 50 subjects with WHO group II anovulation (25 clomifene responsive and 25 clomifene resistant). After a treatment cycle of letrozole, the factors were compared between the subjects who responded and those who failed to respond to treatment.

RESULTS:

Ovulation was achieved in 76% (n = 19) of subjects who had responded to clomifene previously and in 24% (n = 6) with clomifene resistance. The factors associated with letrozole resistance included the presence of hirsutism (odds ratio [OR]: 3.89; 95% confidence interval [CI]: 1.2–12.3) and clomifene resistance (OR: 10.03; 95% CI: 2.81–35.7). The early follicular phase mean (standard deviation) luteinizing hormone level was significantly higher among the nonresponders (9.75 [4.78] – 7.28 [2.3]; P = 0.02). Nonresponders showed significantly lower levels of oestradiol on the 5^th and 9^th days (28.50 [3.39] pg/mL vs. 7.49 [3.62] pg/mL; P = 0.0007 and 142.04 [76.22] pg/mL vs. 28.10 [12.8] pg/mL; P = 0.0001) of the menstrual cycle, respectively.

CONCLUSIONS:

The features associated with resistance to Letrozole at a dose of 2.5 mg show some overlap with those associated with clomifene resistance. However, some features do not show similar association. The effectiveness of letrozole at a dose of 2.5 mg in induction of ovulation among women with clomifene resistance is low and it does not seem to be a suitable treatment at a dose of 2.5 mg for this indication.

Letrozole versus clomiphene citrate in polycystic ovary syndrome: systematic review and meta-analysis

The objective of the present systematic review and meta-analysis was to examine the literature and to identify the results of randomized controlled trials (RCTs) comparing the use of letrozole to clomiphene citrate (CC) for ovulation induction in patients with polycystic ovary syndrome (PCOS). An exhaustive electronic literature search was performed using the MEDLINE and EMBASE databases until October 2014. Seven prospective RCTs comparing the use of letrozole to CC in PCOS patients met the inclusion criteria. Overall, the seven included studies accounted for 1833 patients (906 in the letrozole group and 927 in the CC group) and for 4999 ovulation induction cycles (2455 in the letrozole group and 2544 in the CC group). Five of the included studies reported data on live birth rates. There was a statistically significant increase in the live birth and pregnancy rates in the letrozole group when compared to the CC group, with a relative risk (RR) = 1.55 (95% confidence interval (CI): 1.26-1.90; I(2) = 0%) and RR = 1.38 (95% CI: 1.05-1.83; I(2) = 61%), respectively. There were no differences in the multiple pregnancy, miscarriage and ovulation rates between the two groups. Our study found that letrozole is superior to CC when considering the live birth and pregnancy rates in patients with PCOS.

Congenital malformations among babies born following letrozole or clomiphene for infertility treatment

CONTEXT

Clomiphene citrate (CC) is the first line drug for ovulation induction but because of its peripheral antiestrogenic effect, letrozole was introduced as the 2nd line drug. It lacks the peripheral antiestrogenic effect and is associated with similar or even higher pregnancy rates. Since letrozole is a drug for breast cancer, its use for the purpose of ovulation induction became controversial in the light of studies indicating an increased incidence of congenital malformations.

AIMS

To evaluate and compare the incidence of congenital malformations among offsprings of infertile couples who conceived naturally or with clomiphene citrate or letrozole treatment.

SETTINGS AND DESIGN

A retrospective cohort study done at a tertiary infertility centre.

METHODS AND MATERIAL

A total of 623 children born to infertile women who conceived naturally or following clomiphene citrate or letrozole treatment were included in this study. Subjects were sorted out from medical files of both mother and newborn and follow up study was done based on the information provided by parents through telephonic conversations. Babies with suspected anomaly were called and examined by specialists for the presence of major and minor congenital malformations. Other outcomes like multiple pregnancy rate and birth weight were also studied.

RESULTS

Overall, congenital malformations, chromosomal abnormalities were found in 5 out of 171 (2.9%) babies in natural conception group and 5 out of 201 babies in the letrozole group (2.5%) and in 10 of 251 babies in the CC group (3.9%).

CONCLUSIONS

There was no significant difference in the overall rate of congenital malformations among children born to mothers who conceived naturally or after letrozole or CC treatment.

KEY MESSAGES

Congenital malformations have been found to be comparable following natural conception, letrozole and clomiphene citrate. Thus, the undue fear against letrozole may be uncalled for.

Current evidence supporting "letrozole" for ovulation induction

Aromatase inhibitor “letrozole” was first introduced as a potential ovulation induction (OI) drug almost a decade back. Large number of studies has been published using letrozole for OI: In polycystic ovary syndrome (PCOS) women, clomiphene citrate (CC) resistant women, for intrauterine insemination and also in various protocols of mild stimulation for in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI). Letrozole appears to be a good option, with its oral route of administration, cost, shorter half-life and negligible side effects. However, the verdict on efficacy and safety of letrozole is still uncertain. This review explores the current scientific data supporting letrozole for OI.

Optimal management of subfertility in polycystic ovary syndrome

The purpose of this paper is to provide a stepwise approach to treating the infertility/subfertility associated with polycystic ovary syndrome. Defining polycystic ovary syndrome in a patient requires first investigating other possible causes for polycystic ovary morphology, acne, hirsutism, obesity, and the metabolic derangements that often accompany polycystic ovary syndrome. Beginning with lifestyle modification and use of metformin, the progressive inclusion of more intensive therapies for induction of ovulation is described. Second-line treatments are discussed and the new findings from a large multicenter trial are discussed in the context of evidence-based treatment strategies for first-line agents. Finally, monofollicular development as a treatment goal and in vitro fertilization are discussed for those with recalcitrant disease.

An assessment of current clinical attitudes toward letrozole use in reproductive endocrinology practices

OBJECTIVE

To assess the clinical use and practice attitudes among Society for Assisted Reproductive Technology (SART) members regarding the use of letrozole for ovulation induction and infertility treatment.

DESIGN

The SART clinic physicians were mailed a cover letter and consent form, a two-page survey, and return envelope. The surveys were returned and analyzed using descriptive statistics.

SETTING

Not applicable.

PATIENT(S)

None.

INTERVENTION(S)

A 13-question survey.

MAIN OUTCOME MEASURE(S)

Reproductive endocrinology and infertility physicians use patterns and attitudes regarding letrozole.

RESULT(S)

A total of 77.9% of physician prescribe letrozole. Of those who do not, 32.4% cited concern about the US Food and Drug Administration warning, 35.1% cited satisfaction with current medications, 25.7% cited both reasons, and 6.8% cited no experience with letrozole. Physicians (11.5%) were unaware of the US Food and Drug Administration warning. Physicians (99.7%) were aware that ovulation induction is an off-label use of letrozole. The most common use was for ovulation induction in patients with polycystic ovary syndrome (PCOS). Physicians (14.9%) prescribe letrozole as first-line ovulation therapy prior to clomid, 47.9% use for clomid failures, and 25.7% reported use in both situations.

CONCLUSION(S)

Most physicians surveyed use letrozole for ovulation induction despite the current US Food and Drug Administration warning. Even when accounting for nonrespondents, more than 25% of physicians indicated success with letrozole use. Questions regarding doses and clinical concerns about letrozole revealed no standardized manner of letrozole administration despite wide interest, therefore additional research is warranted.

Fertility management in the PCOS population: results of a web-based survey at IVF-worldwide.com

PURPOSE

To identify the leading treatment strategies for infertile women with PCOS on an international scale.

METHODS

A retrospective evaluation using the results of a web-based survey, (IVF-Worldwide ( www.IVF-worldwide.com ), posted from 1 to 30 September 2010 was performed. Binomial confidence intervals for proportions were calculated by the modified Wald method with significance defined as P < 0.05 using a DataStar software package (DataStar, Waltham, MA, USA). Incomplete surveys were excluded from the analysis.

RESULTS

The results from 262 centers in 68 nations were obtained. Clomiphene citrate was the clear first choice, 68 %, for PCOS treatment in the respondent group. Eighty-eight percent of respondents utilized ultrasound follicular monitoring when conducting ovulation induction with oral medications. A significant (p < 0.05) proportion of respondents (66 %) did use some BMI cutoff beyond which IVF treatment was not offered. The preferred IVF protocols for PCOS patients were gonadotropin releasing hormone (GnRH) antagonist, 46 %, and GnRH agonist, 51 %. There was heterogeneity of responses observed regarding the management of a patient at very high risk of OHSS.

CONCLUSIONS

While some advances, such as the use of GnRH antagonist regimen in IVF cycles, were relatively underutilized, the survey gives an unfiltered snapshot at the practice patterns of a large number of clinics. Results from this survey may be used by researchers and professional organizations to improve the clinical care of PCOS women suffering with infertility.

Clomiphene ovulation induction and higher-order multiple pregnancy

Clomiphene citrate is a widely used treatment for ovulatory dysfunction in women seeking pregnancy. The major adverse consequence of clomiphene use is the increased risk of multiple and higher-order multiple pregnancy. Mechanisms for multiple pregnancy include dosing variation, adjuvant therapies, pretreatment weight loss and a cumulative effect of multiple clomiphene cycles. It has been suggested that the risk of higher-order multiple pregnancy may be reduced with ultrasound monitoring, although there is limited evidence to support this practice.

Clinical review: The use of aromatase inhibitors for ovulation induction and superovulation

CONTEXT

Anovulation is likely responsible for 20% of female infertility. Although clomiphene citrate remains the first-line therapy for ovulation induction in anovulatory patients who are not estrogen-deficient and to treat unexplained infertility, there remains a discrepancy between ovulation and conception rates with its use, attributed to its antiestrogenic effects on cervical mucus and the endometrium. Alternative agents, including aromatase inhibitors, have been used that have not been associated with these side effects.

EVIDENCE ACQUISITION

A literature search was conducted to specifically explore the use of aromatase inhibitors for ovulation induction and superovulation.

EVIDENCE SYNTHESIS

Recent studies have found that aromatase inhibitors may be safe and useful agents for ovulation induction in patients with polycystic ovarian syndrome as well a treatment option for superovulation in patients with either unexplained infertility or endometriosis.

CONCLUSIONS

Aromatase inhibitors may be an effective alternative treatment to clomiphene citrate for both ovulation induction and superovulation.