THE EFFECTS OF CLOMIPHENE CITRATE AND LETROZOLE IN WOMEN WITH PCOS

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。目的：评价枸橼酸克罗米芬和来曲唑对多囊卵巢综合征患者子宫内膜雌激素和孕激素受体表达、妊娠率、流产率、活产率、排卵率及性交后试验结果的影响。研究计划：本研究是一项随机、双盲、交叉研究来曲唑与枸橼酸克罗米芬在18-39岁、根据NIH/NICHD标准诊断为多囊卵巢综合征并希望怀孕的女性中的应用。方法：未怀孕且超声检查无显性卵泡证据的患者将随机分组。患者将通过随机数字表随机分配到柠檬酸克罗米芬50 mg /天，连续5天或来曲唑2.5 mg /天，连续5天。用药结束四天后，患者将返回进行盆腔超声检查。每两天进行一次超声检查，直到：1)通过尿液LH检测或优势卵泡塌陷记录排卵，血清黄体酮大于3 ng/ml，或2)进行了五次超声检查，但未发现卵泡发育的证据。当导卵泡平均直径为16- 18mm时，进行性交后检查和子宫内膜活检（卵泡期）。有排卵记录的患者将在尿LH试验阳性或超声记录卵泡塌陷后9-11天进行血清妊娠试验。子宫内膜活检将在未怀孕的患者（黄体期）进行。妊娠患者（化学妊娠）将根据临床需要进行随访，直到超声检查发现宫内妊娠囊（临床妊娠）或重复血清妊娠试验呈阴性。宫内妊娠的患者将被转介到产科护理，并与产科医生一起随访。疑似异位妊娠的患者将接受治疗。子宫内膜活检标本将被冷冻，使用小鼠单克隆抗体对人雌激素和孕激素受体进行免疫组织化学分析。子宫内膜间质和上皮的免疫组化染色分别为阴性、弱、中等或强。活组织检查的评估对治疗是不透明的。未怀孕的排卵期患者将以诱导排卵的最低剂量治疗长达三个周期。无排卵患者将以增加剂量的研究药物（柠檬酸克罗米芬50mg， 100mg, 150mg；来曲唑2.5mg, 5mg, 7.5mg）治疗最多3个周期。在三个周期后，未怀孕的患者将在一个月的洗脱期后转入另一种药物的治疗。性交后检查和子宫内膜活组织检查只能在第一个排卵周期内进行。临床意义：多囊卵巢综合征（PCOS）是最常见的女性不孕症，影响5-10%的普通人群和20%的不育人群。在PCOS继发无排卵性不孕的女性中，诱导排卵的一线治疗是抗雌激素，最常见的是CC，然而，20%-25%的女性对CC有耐药性，不排卵。此外，临床数据显示，许多多囊卵巢综合征妇女在接受克罗米芬柠檬酸盐治疗排卵后没有怀孕，而怀孕的妇女流产的发生率高于预期。据认为，CC通过阻断下丘脑和垂体水平内源性雌激素的负反馈，促进促黄体生成素和促卵泡激素的脉动释放增加，从而启动或增强排卵。大量实验证据表明，除了刺激促性腺激素分泌短暂增加的理想中枢作用外，CC对周围雌激素靶组织还有其他意想不到的潜在有害影响。这些观察结果归因于CC的抗雌激素作用机制，这涉及长期雌激素受体耗竭。因此，CC可能会对依赖雌激素的生育因素如宫颈粘液的质量和数量以及子宫内膜发育产生负面影响。我们假设在月经周期的早期给药来曲唑会使垂体/下丘脑轴从雌激素负反馈中释放出来，类似于枸橼酸克罗米芬的作用，但没有雌激素受体下调。随后促性腺激素分泌增加，可刺激卵泡发育。我们进一步假设，来曲唑对子宫内膜没有任何直接的抗雌激素作用，可能会降低多囊卵巢综合征孕妇的流产率。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. OBJECTIVE: To evaluate the effect of clomiphene citrate and letrozole on endometrial estrogen and progesterone receptor expression, pregnancy rates, pregnancy loss rate, live-birth rate, ovulation rate, and post-coital test result in women with polycystic ovary syndrome. RESEARCH PLAN: This study is a randomized, double blind, cross over study of letrozole versus clomiphene citrate in women 18-39 years of age with the diagnosis of PCOS based on the NIH/NICHD criteria who desire pregnancy. METHODS: Non-pregnant patients without sonographic evidence of a dominant follicle will be randomized. Patients will be randomized via random number table to treatment with clomiphene citrate 50 mg per day for 5 days or letrozole 2.5 mg per day for 5 days. Four days following completion of the drug the patient will return for a pelvic ultrasound. Ultrasounds will be performed every two days until: 1) ovulation is documented by urine LH detection or collapse of the dominant follicle with serum progesterone greater than 3 ng/ml, or 2) five ultrasounds have been performed without evidence of follicular development. Post-coital testing and endometrial biopsy (follicular phase) will be performed when the lead follicle is 16-18 mm average diameter. Patients with documented ovulation will have a serum pregnancy test performed 9-11 days following either the positive urine LH test or sonographically documented follicular collapse. Endometrial biopsy will be performed on non-pregnant patients (luteal phase). Pregnant patients (chemical pregnancy) will be followed as clinically necessary until an intrauterine gestational sac is seen on ultrasound (clinical pregnancy) or a repeat serum pregnancy test is negative. Patients with an intrauterine pregnancy will be referred for obstetric care and followed in conjunction with the obstetrician. Patients with suspected ectopic gestations will be referred for treatment. Endometrial biopsy specimens will be frozen and immunohistochemical analysis performed using mouse monoclonal antibodies to human estrogen and progesterone receptors. Immunohistochemical staining will be recorded as negative, weak, moderate or strong in both the endometrial stroma and epithelium. The evaluation of the biopsies will be blinded as to treatment. Ovulatory patients who do not conceive will be treated for up to three cycles at the lowest dose that induced ovulation. Anovulatory patients will be treated for up to three cycles at increasing doses of the study drug (clomiphene citrate 50mg, 100mg, 150mg; letrozole 2.5mg, 5mg, 7.5mg). Following three cycles, patients who have not conceived a pregnancy will be crossed-over to treatment with the other drug following a one-month washout. The post-coital test and endometrial biopsies will be performed only during the first ovulatory cycle on each treatment medication. CLINICAL RELEVANCE: Polycystic ovary syndrome (PCOS) is the most common form of female infertility, affecting 5-10% of the general population and 20% of the infertile population. In women with anovulatory infertility secondary to PCOS, the first-line treatment for the induction of ovulation is an antiestrogen, most commonly CC. However, 20%-25% of women are resistant to CC and do not ovulate. In addition, clinical data have revealed that a number of women with PCOS that ovulate with clomiphene citrate therapy do not conceive, and those that conceive demonstrate a higher than expected incidence of miscarriage. It is believed that CC initiates or augments ovulation by blocking negative feedback of endogenous estrogen at the level of the hypothalamus and pituitary, promoting an increase in the pulsatile release of luteinizing hormone and follicle stimulating hormone. A considerable body of experimental evidence suggests that, in addition to its desirable central action of stimulating a transient increase in gonadotropin secretion, CC has other unintended and potentially detrimental effects on peripheral estrogen target tissues. These observations have been attributed to the antiestrogenic mechanism of action of CC, which involves long-lasting estrogen receptor depletion. As a result, CC may negatively effect such estrogen dependent fertility factors as the quality and quantity of cervical mucus and endometrial development. We hypothesized that letrozole administration in the early part of the menstrual cycle would release the pituitary/hypothalamic axis from estrogenic negative feedback, similar to the effect of clomiphene citrate but without estrogen receptor down-regulation. The subsequent increase in gonadotropin secretion could stimulate ovarian follicle development. We further hypothesize that the absence of any direct antiestrogenic effects of letrozole on the endometrium may decrease the miscarriage rate in women with PCOS who become pregnant.