Potential of aromatase inhibitors for ovulation and superovulation induction in infertile women

The comparison between fixed versus degressive doses of medroxyprogesterone acetate combined with letrozole in patients of progestin-primed ovarian stimulation protocol: a propensity score-matched study

Objective

To explore the cycle characteristics and pregnancy outcomes of progestin-primed ovarian stimulation (PPOS) using fixed versus degressive doses of medroxyprogesterone acetate (MPA) in conjunction with letrozole (LE) in infertile women by propensity score matching (PSM) analysis.

Design

A retrospective cohort study.

Setting

Tertiary-care academic medical center.

Population

A total of 3173 infertile women undergoing their first in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment within the period from January 2017 to December 2020.

Methods

A total of 1068 and 783 patients who underwent a fixed dose of MPA combined with LE and a degressive dose of MPA combined with LE protocols, respectively, were enrolled in this study. The freeze-all approach and later frozen-thawed embryo transfer (FET) were performed in both groups. Propensity score matching (1:1) was performed.

Main outcome measures

The primary outcomes were the dosage of MPA and the incidence of premature luteinizing hormone (LH) surges. The secondary outcomes were the number of oocytes retrieved, the cumulative live birth rate (CLBR) and the fetal malformation rate.

Results

We created a perfect match of 478 patients in each group. The dosage of MPA, the LH serum level on the eighth day of stimulation, progesterone (P) level and LH level on the hCG trigger day were significantly higher in the LE + fixed MPA group than in the LE + degressive MPA group (52.1 ± 13.1 mg vs. 44.9 ± 12.5 mg; 5.0 ± 2.7 IU/L vs. 3.7 ± 1.7 IU/L; 0.9 ± 0.5 ng/ml vs. 0.8 ± 0.5 ng/ml; 3.3 ± 2.4 IU/L vs. 2.8 ± 1.9 IU/L; P < 0.01). The duration of Gn, the number of follicles with diameter more than 16 mm on trigger day, the estradiol (E2) level on the hCG trigger day were lower in the LE + fixed MPA group than in the LE + degressive MPA group (9.7 ± 1.7 days vs. 10.3 ± 1.5 days; 5.6 ± 3.0 vs. 6.3 ± 3.0; 1752.5 ± 1120.8 pg/ml vs. 1997.2 ± 1108.5 pg/ml; P < 0.001). No significant difference was found in the incidence of premature LH surge, the number of oocytes retrieved, the number of top-quality embryos, clinical pregnancy rate (CPR), CLBR or fetal malformation rate between the two groups.

Conclusion

The combination of a degressive MPA dose with LE proved effective in reducing the total MPA dosage with comparable premature LH surge and pregnancy outcomes in women undergoing the PPOS protocol.

Comparative Evaluation of Sildenafil Citrate and Estrogen as an Adjuvant Therapy for Treatment of Unexplained Infertility in Women

BACKGROUND

Uterine blood flow determines endometrial thickness. This study examined how vaginal sildenafil citrate and estradiol valerate altered endometrial thickness, blood flow, and fertility in infertile women.

METHODS

This study observed 148 infertile women whose infertility was unexplained. Group 1 comprised 48 patients who received oral estradiol valerate (Cyclo-Progynova 2 mg/12 h white tablets) from day 6 till ovulation was initiated with clomiphene citrate. A number of 50 participants in group 2 received oral sildenafil (Respatio 20 mg/12 h film-coated tablets) for 5 days starting the day after their previous menstrual period and finishing on the day they ovulated with clomiphene citrate. Group 3 was the control group, with 50 patients receiving clomiphene citrate (Technovula 50 mg/12 h tablets) ovulation induction from the 2nd to 7th day of cycle. All patients had transvaginal ultrasounds to determine ovulation, follicle count, and fertility. Miscarriage, ectopic pregnancy, and multiple pregnancies were monitored for three months.

RESULTS

The three groups' mean ETs differed statistically at p = 0.0004. A statistically significant difference was found between the three groups in terms of the number of follicles, with 69% of patients in group 1 having one and 31% having two or more, 76% of patients in group 2 having one and 24% having two or more, and 90% of patients in the control group having one and 10% having two or more (p = 0.038). The clinical pregnancy rates of the three groups were 58%, 46%, and 27%, respectively (p = 0.005). The distribution of all side effects was not statistically different between the three groups.

CONCLUSION

It is possible to claim that adding oral estrogen to clomiphene citrate therapy as an adjuvant therapy can improve endometrial thickness and, as a result, increase the pregnancy rates in unexplained infertility compared to sildenafil, especially in cases where the infertility has lasted less than two years. Most people who take sildenafil end up with a mild headache.

Oral Drugs for Unexplained Infertility

Of the infertile couples unable to conceive without any identifiable cause, 30 % are defined as having unexplained infertility. Management depends on duration of infertility and age of female partner. The treatment of unexplained infertility is empirical, and many different regimens have been used. Among these are expectant management, ovarian stimulation with clomiphene citrate, gonadotropins and aromatase inhibitors, fallopian tube sperm perfusion, tubal flushing, intrauterine insemination, gamete intrafallopian transfer, and IVF. The first approach to treatment of unexplained infertility generally is the use of drugs that stimulate oocyte production. For over four decades, the first-line treatment for ovarian stimulation in unexplained infertility has been clomiphene citrate. Multiple reports suggest that aromatase inhibitors may be effective alternative agents for ovarian stimulation in couples with unexplained infertility. Their administration is reported to be associated with monofollicular development in most cases, which may result in enhanced fertility and a reduced risk of ovarian hyperstimulation and multiple births, as compared to current standard therapies such as gonadotropin and clomiphene. Despite world evidence to the contrary, letrozole has been banned for use for infertility management in India since 2011.

Use of aromatase inhibitors as first- and second-line medical therapy in patients with endometrial adenocarcinoma: a retrospective study

OBJECTIVES

The primary objective of this study was to examine the role of aromatase inhibitors (AIs) as first- or second-line medical treatment in women with endometrial adenocarcinoma who were not candidates for surgical management. The secondary objective was to examine the role of AIs in adjuvant and palliative treatment.

METHODS

Thirty women with endometrial adenocarcinoma who were treated with aromatase inhibitors between 2000 and 2010 at the Tom Baker Cancer Centre in Calgary, Alberta were assessed in a retrospective analysis. Disease response was based on response evaluation criteria in solid tumours. Kruskal-Wallis test was used to compare non-parametric variables and Fisher exact test was used to compare the health variables.

RESULTS

Seventeen patients received AIs as first- or second-line medical treatment, five received adjuvant therapy, and eight received palliative treatment. The median age of patients in the first or second line medical treatment group was significantly greater than that of patients in the adjuvant or palliative group (P = 0.042). There was no significant difference in median weight or body mass index. The subjective clinical response rate with medical treatment was 70%. In the first- or second-line medical treatment group, only seven patients had available response data. Our study showed stable disease in 5/7 (71%), partial response in 1/7 (14%), and progression in 1/7 (14%) patients.

CONCLUSION

This retrospective clinical series examining use of an aromatase inhibitor as first- or second-line medical therapy in women with endometrial carcinoma showed that AIs are a potential treatment for patients who have a contraindication to surgery and who either have failed or cannot use megestrol therapy.

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.

Options on fertility preservation in female cancer patients

Infertility following treatment of cancer is a quality of survival's recognized issue and efforts should be made to help young cancer patients retaining their fertility potential. Options to preserve fertility in female patients include well established methods such as shielding to reduce radiation damage to reproductive organs, fertility-sparing surgery and emergency in vitro fertilization after controlled ovarian stimulation, aiming at freezing embryos. Transfer of frozen/thawed embryos today is a clinical routine in fertility clinics worldwide and it has been used for over 25 years. Mature oocytes after ovarian stimulation can also be frozen unfertilized, nevertheless overall pregnancy rates after fertilization of frozen-thawn oocytes are still relatively lower than those with embryo freezing. Remaining fertility preservation options are still in development and include the freezing of immature oocytes aiming at later in vitro maturing and fertilizing them and the cryopreservation of ovarian tissue for future retransplantation or for in vitro growth and maturation of follicles, both still experimental.

Pituitary-ovary-spleen axis in ovulation

Leukocytes are rapidly recruited to the preovulatory ovary and play a crucial role as facilitators of ovulation and luteal formation. In this article, recent findings on leukocyte trafficking to the ovary, as well as the physiological role of leukocytes in the ovary, will be summarized and discussed. We then explore the novel hypothesis that the hypothalamus-pituitary-ovary (HPO) axis might include the spleen as a reservoir of leukocytes by summarizing recent reports on this topic, both in the fields of immunology and reproductive biology.

Aromatase Inhibitors for Ovulation and Pregnancy in Polycystic Ovary Syndrome

Objective:

To evaluate evidence for use of aromatase inhibitors for ovulation induction and pregnancy in patients with polycystic ovary syndrome (PCOS).

Data Sources:

A MEDLINE search (1966–May 2009) was conducted using the search terms anastrozole, aromatase inhibitors, axemestane, letrozole, ovulation, and polycystic ovary syndrome to identify relevant studies.

Study Selection and Data Extraction:

Prospective clinical trials published in English and conducted in humans were identified. Trials using intrauterine insemination methods for pregnancy were excluded. The resulting articles were separated into 2 groups: aromatase inhibitor use in clomiphene-resistant patients and use in treatment-naive patients. Eleven trials were reviewed.

Data Synthesis:

Accepted pharmacologic treatments for women with PCOS and infertility include clomiphene citrate, gonadotropins, and gonadotropin-releasing hormone (GnRH) analogs. Each medication has variable efficacy rates and adverse effects. Therefore, other treatments are needed for a subset of women with PCOS and infertility. Evidence suggests that nonsteroidal aromatase inhibitors, specifically letrozole and anastrozole, may have ovulation-inducing effects by inhibiting androgen-to-estrogen conversion. Select trials with aromatase inhibitors have demonstrated efficacy for increased endometrium thickness, ovulation rates, and pregnancy rates when used in clomiphene citrate–resistant or treatment-naïve patients.

Conclusions:

Further trials comparing aromatase inhibitors with clomiphene citrate are necessary before aromatase inhibitors can be recommended routinely for ovulation induction in women with PCOS and infertility. However, aromatase inhibitors may be considered in a subset of this population, specifically women who are clomiphene citrate resistant or those who, after discussion of risks and benefits, are not candidates for clomiphene citrate, gonadotropins, or GnRH analogs.

Use of letrozole in assisted reproduction: a systematic review and meta-analysis

BACKGROUND

Letrozole is the third-generation aromatase inhibitor (AI) most widely used in assisted reproduction. AIs induce ovulation by inhibiting estrogen production; the consequent hypoestrogenic state increases GnRH release and pituitary follicle-stimulating hormone (FSH) synthesis.

METHODS

A systematic search of the literature was performed for both prospective and retrospective studies. Meta-analyses of randomized clinical trials (RCTs) were performed for three comparisons: letrozole versus clomiphene citrate (CC), letrozole + FSH versus FSH in intrauterine insemination (IUI) and letrozole + FSH versus FSH in IVF. In the absence of RCTs, non-randomized studies were pooled.

RESULTS

Nine studies were included in the meta-analysis. Four RCTs compared the overall effect of letrozole with CC in patients with polycystic ovary syndrome. The pooled result was not significant for ovulatory cycles (OR = 1.17; 95% CI 0.66–2.09), or for pregnancy rate per cycle (OR = 1.47; 95% CI 0.73–2.96) or for pregnancy rate per patient (OR = 1.37; 95% CI 0.70–2.71). In three retrospective studies which compared L + FSH with FSH in ovarian stimulation for IUI, the pooled OR was 1.15 (95% CI 0.78−1.71). A final meta-analysis included one RCT and one cohort study that compared letrozole + gonadotrophin versus gonadotrophin alone: the pooled pregnancy rate per patient was not significantly different (OR = 1.40; 95% CI 0.67–2.91).

CONCLUSIONS

Letrozole is as effective as other methods of ovulation induction. Further randomized-controlled studies are warranted to define more clearly the efficacy and safety of letrozole in human reproduction.