Esther Eisenberg

Letrozole versus Clomiphene for Infertility in the Polycystic Ovary Syndrome

BACKGROUND Clomiphene is the current first-line infertility treatment in women with the polycystic ovary syndrome, but aromatase inhibitors, including letrozole, might result in better pregnancy outcomes. METHODS In this double-blind, multicenter trial, we randomly assigned 750 women, in a 1:1 ratio, to receive letrozole or clomiphene for up to five treatment cycles, with visits to determine ovulation and pregnancy, followed by tracking of pregnancies. The polycystic ovary syndrome was defined according to modified Rotterdam criteria (anovulation with either hyperandrogenism or polycystic ovaries). Participants were 18 to 40 years of age, had at least one patent fallopian tube and a normal uterine cavity, and had a male partner with a sperm concentration of at least 14 million per milliliter; the women and their partners agreed to have regular intercourse with the intent of conception during the study. The primary outcome was live birth during the treatment period. RESULTS Women who received letrozole had more cumulative live births than those who received clomiphene (103 of 374 [27.5%] vs. 72 of 376 [19.1%], P=0.007; rate ratio for live birth, 1.44; 95% confidence interval, 1.10 to 1.87) without significant differences in overall congenital anomalies, though there were four major congenital anomalies in the letrozole group versus one in the clomiphene group (P=0.65). The cumulative ovulation rate was higher with letrozole than with clomiphene (834 of 1352 treatment cycles [61.7%] vs. 688 of 1425 treatment cycles [48.3%], P<0.001). There were no significant between-group differences in pregnancy loss (49 of 154 pregnancies in the letrozole group [31.8%] and 30 of 103 pregnancies in the clomiphene group [29.1%]) or twin pregnancy (3.4% and 7.4%, respectively). Clomiphene was associated with a higher incidence of hot flushes, and letrozole was associated with higher incidences of fatigue and dizziness. Rates of other adverse events were similar in the two treatment groups. CONCLUSIONS As compared with clomiphene, letrozole was associated with higher live-birth and ovulation rates among infertile women with the polycystic ovary syndrome. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and others; ClinicalTrials.gov number, NCT00719186.).

Total testosterone assays in women with polycystic ovary syndrome: Precision and correlation with hirsutism

CONTEXT There is no standardized assay of testosterone in women. Liquid chromatography mass spectrometry (LC/MS) has been proposed as the preferable assay by an Endocrine Society Position Statement. OBJECTIVE The aim was to compare assay results from a direct RIA with two LC/MS. DESIGN AND SETTING We conducted a blinded laboratory study including masked duplicate samples at three laboratories--two academic (University of Virginia, RIA; and Mayo Clinic, LC/MS) and one commercial (Quest, LC/MS). PARTICIPANTS AND INTERVENTIONS Baseline testosterone levels from 596 women with PCOS who participated in a large, multicenter, randomized controlled infertility trial performed at academic health centers in the United States were run by varying assays, and results were compared. MAIN OUTCOME MEASURE We measured assay precision and correlation and baseline Ferriman-Gallwey hirsutism scores. RESULTS Median testosterone levels were highest with RIA. The correlations between the blinded samples that were run in duplicate were comparable. The correlation coefficient (CC) between LC/MS at Quest and Mayo was 0.83 [95% confidence interval (CI), 0.80-0.85], between RIA and LC/MS at Mayo was 0.79 (95% CI, 0.76-0.82), and between RIA and LC/MS at Quest was 0.67 (95% CI, 0.63-0.72). Interassay variation was highest at the lower levels of total testosterone (≤50 ng/dl). The CC for Quest LC/MS was significantly different from those derived from the other assays. We found similar correlations between total testosterone levels and hirsutism score with the RIA (CC=0.24), LC/MS at Mayo (CC=0.15), or Quest (CC=0.17). CONCLUSIONS A testosterone RIA is comparable to LC/MS assays. There is significant variability between LC/MS assays and poor precision with all assays at low testosterone levels.

Progesterone and transforming growth factor-β coordinately regulate suppression of endometrial matrix metalloproteinases in a model of experimental endometriosis

Endometriosis is a benign, though aggressive, disease of the female reproductive tract that consists of endometrial stromal and epithelial cells growing at an extrauterine site. Although it is widely accepted that the majority of cases of endometriosis result from the ectopic implantation of refluxed menstrual tissue, the precise mechanisms by which this disease becomes established are not well understood. Matrix metalloproteinases (MMPs), enzymes which are important for extracellular matrix turnover, have recently been implicated in the development of endometriosis. MMPs appear to be overexpressed in endometriotic lesions, but expression levels decrease following successful medical therapy. Intriguingly, although transforming growth factor-beta (TGF-beta) mediates progesterone suppression of specific endometrial MMPs, this growth factor is overexpressed in women with endometriosis. In the current study, we used an established experimental model of endometriosis to explore MMP regulation by TGF-beta. Our findings indicate that blocking the action of TGF-beta opposes progesterone-mediated suppression of MMPs and blocks the ability of this steroid to prevent experimental endometriosis. However, we also show that the action of TGF-beta does not lead to a sustained suppression of MMPs as observed following progesterone treatment. Taken together, our data suggest that in the absence of a normal progesterone response, common in ectopic lesions of endometriosis, sensitivity to TGF-beta may be altered, resulting in a failure to regulate MMPs.

Letrozole, gonadotropin, or clomiphene for unexplained infertility

BACKGROUND The standard therapy for women with unexplained infertility is gonadotropin or clomiphene citrate. Ovarian stimulation with letrozole has been proposed to reduce multiple gestations while maintaining live birth rates. METHODS We enrolled couples with unexplained infertility in a multicenter, randomized trial. Ovulatory women 18 to 40 years of age with at least one patent fallopian tube were randomly assigned to ovarian stimulation (up to four cycles) with gonadotropin (301 women), clomiphene (300), or letrozole (299). The primary outcome was the rate of multiple gestations among women with clinical pregnancies. RESULTS After treatment with gonadotropin, clomiphene, or letrozole, clinical pregnancies occurred in 35.5%, 28.3%, and 22.4% of cycles, and live birth in 32.2%, 23.3%, and 18.7%, respectively; pregnancy rates with letrozole were significantly lower than the rates with standard therapy (gonadotropin or clomiphene) (P=0.003) or gonadotropin alone (P<0.001) but not with clomiphene alone (P=0.10). Among ongoing pregnancies with fetal heart activity, the multiple gestation rate with letrozole (9 of 67 pregnancies, 13%) did not differ significantly from the rate with gonadotropin or clomiphene (42 of 192, 22%; P=0.15) or clomiphene alone (8 of 85, 9%; P=0.44) but was lower than the rate with gonadotropin alone (34 of 107, 32%; P=0.006). All multiple gestations in the clomiphene and letrozole groups were twins, whereas gonadotropin treatment resulted in 24 twin and 10 triplet gestations. There were no significant differences among groups in the frequencies of congenital anomalies or major fetal and neonatal complications. CONCLUSIONS In women with unexplained infertility, ovarian stimulation with letrozole resulted in a significantly lower frequency of multiple gestation but also a lower frequency of live birth, as compared with gonadotropin but not as compared with clomiphene. (Funded by the National Institutes of Health and others; ClinicalTrials.gov number, NCT01044862.).

Paracrine Mediators of Endometrial Matrix Metalloproteinase Expression

Abstract: The endometrial lining of the human uterus is a highly specialized, steroid‐sensitive tissue. Throughout the reproductive years, the endometrium undergoes dramatic cycles of growth, differentiation, and breakdown under the influence of ovarian steroids. In response to changes in steroid exposure throughout the menstrual cycle, the endometrium produces an array of bioactive growth factors and other cytokines that are critical components of paracrine communication. For example, cell‐cell communication via paracrine factors directs the expression of matrix metalloproteinases (MMPs), enzymes that mediate tissue remodeling during the menstrual cycle. The disease endometriosis is thought to occur as a consequence of retrograde menstruation, and MMPs appear to contribute to the establishment and progression of ectopic endometrial growth in the peritoneal cavity. Although the risk for developing endometriosis is linked to a womans steroid exposure, locally produced paracrine factors can modify steroid action on multiple gene targets, including the MMPs. Estrogen‐associated growth factors as well as inflammatory cytokines are potent stimulators of MMP expression and may contribute to the ability of endometrial fragments to invade the peritoneal surface and establish ectopic sites of growth. In contrast, paracrine factors associated with progesterone action during early pregnancy inhibit MMP expression and prevent ectopic endometrial growth in an experimental model. For example, locally produced retinoic acid and transforming growth factor‐β (TGF‐β) act in concert with progesterone to suppress MMPs, while enhancing expression of MMP inhibitors (TIMPs) during endometrial differentiation. Targeting pregnancy‐associated factors that inhibit endometrial‐specific MMP expression and action may enhance the effectiveness of progestin‐related treatments for endometriosis.

The Potential Role of Environmental Toxins in the Pathophysiology of Endometriosis

Environmental contaminants that are known to disrupt steroid action can influence the development of reproductive diseases. Our group has focused on whether 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD or dioxin) can disrupt steroid regulation of endometrial matrix metalloproteinase (MMP) expression. The MMPs regulate extracellular matrix turnover in normal tissues, but the inappropriate expression of these enzymes is associated with numerous disease states that involve invasive processes. We have previously shown that secretion of MMPs by human endometrium is critical for establishment of ectopic lesions in a nude mouse model of experimental endometriosis. In this report, we show that TCDD exposure promotes establishment of experimental endometriosis by interfering with the ability of progesterone to suppress endometrial MMP expression.

The Pregnancy in Polycystic Ovary Syndrome II (PPCOS II) trial: Rationale and design of a double-blind randomized trial of clomiphene citrate and letrozole for the treatment of infertility in women with polycystic ovary syndrome

Polycystic Ovary Syndrome (PCOS) is a common cause of female infertility and first line treatment is currently oral clomiphene citrate, a selective estrogen receptor modulator, which results in both a high nonresponse rate and multiple pregnancy rate. Aromatase inhibitors such as letrozole may have more favorable ovarian and endometrial effects. The goal of the Pregnancy in Polycystic Ovary Syndrome II (PPCOSII) study is to determine the safety and efficacy of clomiphene citrate (CC) compared to letrozole, in achieving live birth in infertile women with PCOS. The population will consist of 750 infertile women with PCOS. Additionally, the couple will have no other major infertility factor. This will be a multi-center, prospective, double-blind clinical trial of CC vs. letrozole for 5 treatment cycles (or approximately up to 25 weeks). The randomization scheme will be coordinated through the central data coordinating center (DCC) and the randomization is stratified by each participating site. After progestin withdrawal as needed, 750 women will be equally randomized to two different treatment arms: A) CC 50mg every day for 5 days (days 3-7 of cycle), or B) letrozole 2.5mg every day for 5 days (days 3-7 of cycle), for a total of 5 cycles or 25 weeks. The dose will be increased in subsequent cycles in both treatment groups for non-response or poor ovulatory response up to a maximum of 150 mg of CC a day (×5 days) or 7.5mg of letrozole a day (×5 days). The primary analysis will use an intent-to-treat approach to examine differences in the live birth rate in the two treatment arms.

Progesterone-Mediated Endometrial Maturation Limits Matrix Metalloproteinase (MMP) Expression in an Inflammatory-like Environment

Abstract: The human endometrium exhibits regular cycles of growth, differentiation, and breakdown in response to changing levels of ovarian steroids. Following the tissue loss and repair processes of menstruation, rising levels of estradiol initiate a development‐like process leading to a complete restructuring of the endometrial surface. In contrast, while under the predominate influence of progesterone, proliferation declines as cell‐specific differentiation prepares the endometrium for pregnancy over a 5‐ to 6‐day period. In the absence of nidation, steroid support is lost; the endometrial surface begins a complex process of tissue breakdown and bleeding, producing a viscous mixture of cellular debris within a bloody menstrual effluent. Although most of the menstrual fluid exits the body, reflux of some material occurs in most women, providing a poorly understood opportunity for ectopic endometrial growth and establishment of the disease endometriosis. The cyclic restructuring of the endometrium requires numerous matrix metalloproteinases (MMPs) that mediate normal and pathological tissue turnover throughout the reproductive tract. The expression of multiple MMPs facilitates degradation of extracellular matrix during growth‐related remodeling as well as tissue breakdown at the time of menstruation. However, these enzymes are absent during the early and midsecretory phase and the suppression of endometrial MMPs remains important to maintaining the integrity of the endometrium during the highly invasive events required to establish a normal hemochorial placenta. Several research groups have suggested that steroid‐mediated expression and action of MMPs during the menstrual cycle may provide a key mechanistic link between endometrial turnover and the invasive processes necessary for establishment of endometriosis.

Endometrial Shedding Effect on Conception and Live Birth in Women With Polycystic Ovary Syndrome

OBJECTIVE: To estimate whether progestin-induced endometrial shedding, before ovulation induction with clomiphene citrate, metformin, or a combination of both, affects ovulation, conception, and live birth rates in women with polycystic ovary syndrome (PCOS). METHODS: A secondary analysis of the data from 626 women with PCOS from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Cooperative Reproductive Medicine Network trial was performed. Women had been randomized to up to six cycles of clomiphene citrate alone, metformin alone, or clomiphene citrate plus metformin. Women were assessed for occurrence of ovulation, conception, and live birth in relation to prior bleeding episodes (after either ovulation or exogenous progestin-induced withdrawal bleed). RESULTS: Although ovulation rates were higher in cycles preceded by spontaneous endometrial shedding than after anovulatory cycles (with or without prior progestin withdrawal), both conception and live birth rates were significantly higher after anovulatory cycles without progestin-induced withdrawal bleeding (live births per cycle: spontaneous menses 2.2%; anovulatory with progestin withdrawal 1.6%; anovulatory without progestin withdrawal 5.3%; P<.001). The difference was more marked when rate was calculated per ovulation (live births per ovulation: spontaneous menses 3.0%; anovulatory with progestin withdrawal 5.4%; anovulatory without progestin withdrawal 19.7%; P<.001). CONCLUSION: Conception and live birth rates are lower in women with PCOS after a spontaneous menses or progestin-induced withdrawal bleeding as compared with anovulatory cycles without progestin withdrawal. The common clinical practice of inducing endometrial shedding with progestin before ovarian stimulation may have an adverse effect on rates of conception and live birth in anovulatory women with PCOS. LEVEL OF EVIDENCE: II

The Pregnancy in Polycystic Ovary Syndrome II study: baseline characteristics and effects of obesity from a multicenter randomized clinical trial

OBJECTIVE To summarize baseline characteristics from a large multicenter infertility clinical trial. DESIGN Cross-sectional baseline data from a double-blind randomized trial of two treatment regimens (letrozole vs. clomiphene). SETTING Academic Health Centers throughout the United States. PATIENT(S) Seven hundred fifty women with polycystic ovary syndrome (PCOS) and their male partners took part in the study. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Historic, biometric, biochemical, and questionnaire parameters. RESULT(S) Females averaged 30 years and were obese (body mass index [BMI] 35) with ∼20% from a racial/ethnic minority. Most (87%) were hirsute and nulligravid (63%). Most of the women had an elevated antral follicle count and enlarged ovarian volume on ultrasound. Women had elevated mean circulating androgens, LH-to-FSH ratio (∼2), and antimüllerian hormone levels (8.0 ng/mL). In addition, women had evidence for metabolic dysfunction with elevated mean fasting insulin and dyslipidemia. Increasing obesity was associated with decreased LH-to-FSH levels, antimüllerian hormone levels, and antral follicle counts but increasing cardiovascular risk factors, including prevalence of the metabolic syndrome. Men were obese (BMI 30) and had normal mean semen parameters. CONCLUSION(S) The treatment groups were well matched at baseline. Obesity exacerbates select female reproductive and most metabolic parameters. We have also established a database and sample repository that will eventually be accessible to investigators. CLINICAL TRIAL REGISTRATION NUMBER NCT00719186.