Effects of letrozole cotreatment on endocrinology and follicle development in women undergoing ovarian stimulation in an antagonist protocol

Impact of 2.5 mg versus 5 mg letrozole co-treatment in an antagonist protocol for IVF: a retrospective study

Objective

The present study aimed to compare the effectiveness of two different doses of letrozole (2.5 mg and 5 mg daily) in an antagonist protocol for infertile women with normal ovarian reserve.

Methods

This retrospective cohort study included infertile women who underwent in vitro fertilization treatment with letrozole co-treatment at doses of 2.5 mg and 5 mg from 2007 - 2021 at Shanghai Ninth People's Hospital (Shanghai, China). The control group comprised infertile women who received gonadotropin-releasing hormone antagonist alone. The primary outcome was the cumulative live birth rate, while secondary outcomes included follicular phase endocrine parameters, ovarian stimulation outcomes, pregnancy outcomes, and the incidences of maternal and neonatal complications. Baseline and follow-up data were compared between the groups using ANOVA for normally distributed variables, the Kruskal-Wallis test for non-normally distributed variables, and the Chi-square test for categorical variables.

Results

A total of 422 participants were enrolled in the study, with 211 women in the antagonist group, 109 women in the 2.5 mg letrozole co-treatment group, and 102 women in the 5 mg letrozole co-treatment group. Letrozole co-treatment significantly suppressed oestradiol and follicle-stimulating hormone concentrations from stimulation day 5 and onwards, while increasing luteinizing hormone levels on stimulation day 5 and trigger day. The effect was more pronounced with a 5 mg dose of letrozole compared to a 2.5 mg dose (P < 0.05). Administration of 5 mg letrozole reduced the gonadotropin dose (P < 0.05) without negatively affecting the number of oocytes retrieved and subsequent embryo parameters (P > 0.05). The analysis of cumulative live birth rates showed rates of 29.4% in the letrozole 5 mg group, 27.5% in the letrozole 2.5 mg group, and 33.6% in the control group, with no statistically significant difference (P > 0.05). There were no reported pregnancy complications in the two letrozole groups. Additionally, there were no significant differences among the three groups in terms of gestational age and birth weight for both singleton and twin births.

Conclusion

This study indicates that the administration of letrozole in an antagonist protocol, at both 2.5 mg and 5 mg dosages, results in comparable clinical outcomes.

Impact of letrozole co-treatment during ovarian stimulation on oocyte yield, embryo development, and live birth rate in women with normal ovarian reserve: secondary outcomes from the RIOT trial

STUDY QUESTION

Does letrozole (LZ) co-treatment during ovarian stimulation with gonadotropins for in IVF impact follicle recruitment, oocyte number and quality, embryo quality, or live birth rate (LBR)?

SUMMARY ANSWER

No impact of LZ was found in follicle recruitment, number of oocytes, quality of embryos, or LBR.

WHAT IS KNOWN ALREADY

Multi-follicle stimulation for IVF produces supra-physiological oestradiol levels. LZ is an aromatase inhibitor that lowers serum oestradiol thus reducing negative feedback and increasing the endogenous gonadotropins in both the follicular and the luteal phases, effectively normalizing the endocrine milieu during IVF treatment.

STUDY DESIGN, SIZE, DURATION

Secondary outcomes from a randomized, double-blind placebo-controlled trial (RCT) investigating once-daily 5 mg LZ or placebo during stimulation for IVF with FSH. The RCT was conducted at four fertility clinics at University Hospitals in Denmark from August 2016 to November 2018 and pregnancy outcomes of frozen-thawed embryo transfers (FET) registered until May 2023.

PARTICIPANTS/MATERIALS, SETTING, METHODS

One hundred fifty-nine women with expected normal ovarian reserve (anti-Müllerian hormone 8-32 nmol/l) were randomized to either co-treatment with LZ (n = 80) or placebo (n = 79). In total 1268 oocytes were aspirated developing into 386 embryos, and morphology and morphokinetics were assessed. One hundred twenty-nine embryos were transferred in the fresh cycle and 158 embryos in a subsequent FET cycle. The effect of LZ on cumulative clinical pregnancy rate (CPR), LBR, endometrial thickness in the fresh cycle, and total FSH consumption was reported.

MAIN RESULTS AND THE ROLE OF CHANCE

The proportion of usable embryos of retrieved oocytes was similar in the LZ group and the placebo group with 0.31 vs 0.36 (mean difference (MD) -0.05, 95% CI (-0.12; 0.03), P = 0.65). The size and number of aspirated follicles at oocyte retrieval were similar with 11.8 vs 10.3 follicles per patient (MD 1.5, 95% CI (-0.5; 3.1), P = 0.50), as well as the number of retrieved oocytes with 8.0 vs 7.9 oocytes (MD 0.1, 95% CI (-1.4; 1.6), P = 0.39) in the LZ and placebo groups, respectively. The chance of retrieving an oocyte from the 13 to 16 mm follicles at trigger day was 66% higher (95% CI (24%; 108%), P = 0.002) in the placebo group than in the LZ group, whilst the chance of retrieving an oocyte from the ≥17 mm follicles at trigger day was 50% higher (95% CI (2%; 98%), P = 0.04) in the LZ group than in the placebo group. The proportion of fertilized oocytes with two-pronuclei per retrieved oocytes or per metaphase II oocytes (MII) (the 2PN rates) were similar regardless of fertilization with IVF or ICSI with 0.48 vs 0.57 (MD -0.09, 95% CI (-0.24; 0.04), P = 0.51), and 0.62 vs 0.64 (MD -0.02, 95% CI (-0.13; 0.07), P = 0.78) in the LZ and placebo groups, respectively. However, the MII rate in the ICSI group was significantly lower with 0.75 vs 0.88 in the LZ vs the placebo group (MD -0.14, 95% CI (-0.22; -0.06), P = 0.03). Blastocysts on Day 5 per patient were similar with 1.5 vs 2.0, P = 0.52, as well as vitrified blastocysts per patient Day 5 with 0.8 vs 1.2 in (MD -0.4, 95% CI (-1.0; 0.2), P = 0.52) and vitrified blastocysts per patient Day 6 with 0.6 vs 0.6 (MD 0, 95% CI (-0.3; 0.3), P = 1.00) in the LZ vs placebo group, respectively. Morphologic evaluation of all usable embryos showed a similar distribution in 'Good', 'Fair', and 'Poor', in the LZ vs placebo group, with an odds ratio (OR) of 0.8 95% CI (0.5; 1.3), P = 0.68 of developing a better class embryo. Two hundred and ninety-five of the 386 embryos were cultured in an embryoscope. Morphokinetic annotations showed that the odds of having a high KIDscore™ D3 Day 3 were 1.2 times higher (CI (0.8; 1.9), P = 0.68) in the LZ group vs the placebo group. The CPR per transfer was comparable with 31% vs 39% (risk-difference of 8%, 95% CI (-25%; 11%), P = 0.65) in the LZ and placebo group, respectively, as well as CPR per transfer adjusted for day of transfer, oestradiol and progesterone levels at trigger, progesterone levels mid-luteal, and number of oocytes retrieved (adjusted OR) of 0.8 (95% CI (0.4; 1.6), P = 0.72). Comparable LBR were found per transfer 28% vs 37% (MD -9%, 95% CI (-26%; 9%), P = 0.60) and per randomized women 24% vs 30% (MD of -6%, CI (-22%; 8%), P = 0.60) in the LZ group and placebo group, respectively. Furthermore, 4.8 years since the last oocyte aspiration, a total of 287 of 386 embryos have been transferred in the fresh or a subsequently FET cycle, disclosing the cumulative CPR, which is similar with 38% vs 34% (MD 95% CI (8%; 16%), P = 0.70) in the LZ vs placebo group.

LIMITATIONS, REASONS FOR CAUTION

Both cleavage stage and blastocyst transfer and vitrification were permitted in the protocol, making it necessary to categorize their quality and pool the results. The study was powered to detect hormonal variation but not embryo or pregnancy outcomes.

WIDER IMPLICATIONS OF THE FINDINGS

The similar utilization rate and quality of the embryos support the use of LZ co-treatment for IVF with specific indication as fertility preservation, patients with previous cancer, or poor responders. The effect of LZ on mature oocytes from different follicle sizes and LBRs should be evaluated in a meta-analysis or a larger RCT.

STUDY FUNDING/COMPETING INTEREST(S)

Funding was received from EU Interreg for ReproUnion, Sjaelland University Hospital, Denmark, Ferring Pharmaceuticals, and Gedeon Ricther. Roche Diagnostics contributed with assays. A.P. has received grants from Ferring, Merck Serono, and Gedeon Richter, consulting fees from Preglem, Novo Nordisk, Ferring, Gedeon Richter, Cryos, & Merck A/S, speakers fees from Gedeon Richter, Ferring, Merck A/S, Theramex, & Organon, and travel support from Gedeon Richter. The remaining authors declare that they have no competing interests in the research or publication.

TRIAL REGISTRATION NUMBERS

NCT02939898 and NCT02946684.

The effect of gonadotrophin-releasing hormone agonist versus human chorionic gonadotrophin trigger on pregnancy and neonatal outcomes in Letrozole-HMG IUI cycles

BACKGROUND

GnRHa and hCG are both used for oocyte maturation and ovulation triggering. However, GnRHa have a shorter half-life than hCG, which leads to luteal phase deficiency. Letrozole (LE) has been found to improve the luteal function. Thus, the choice of triggering strategy can be different in intrauterine insemination (IUI) cycles using LE and human menopausal gonadotropin (HMG). The aim of this study was to compare the pregnancy and neonatal outcomes of patients triggered with GnRHa versus hCG versus dual trigger in LE-IUI cycles.

METHODS

This retrospective cohort study included 6,075 LE-HMG IUI cycles between January 2010 and May 2021 at a tertiary-care academic medical center in China. All cycles were divided into three groups according to different trigger strategies as hCG trigger group, GnRHa trigger group and dual trigger group. The primary outcome was clinical pregnancy rate. Logistic regression analysis was performed to explore other risk factors for clinical pregnancy rate.

RESULTS

No significant difference was observed in clinical pregnancy rate between hCG, GnRHa and dual trigger cycles in LE-HMG IUI cycles (P = 0.964). The miscarriage rate was significantly lower in the GnRHa trigger group, and higher in the dual trigger group, compared with the hCG group (P = 0.045). Logistic analysis confirmed that triggering strategy was associated with miscarriage (aOR:0.427, 95%CI: 0.183-0.996, P = 0.049; aOR:0.298, 95%CI: 0.128-0.693, P = 0.005). No significant differences were observed regarding neonatal outcomes between the three groups.

CONCLUSIONS

Our findings suggested that both GnRHa and dual trigger can be used to trigger ovulation in LE-HMG IUI cycles, but dual trigger must be used with caution.

Corifolitropin-Alfa plus Five Days Letrozole Versus Daily Recombinant-FSH in Expected Normo-Responder Patients: A Retrospective Comparative Study

Background: In recent times, different novel GnRH-antagonist protocols with various combinations of gonadotropins and other molecules (e.g., aromatase inhibitors, selective estrogen receptor modulators) have been proposed for expected normal ovarian responders undergoing assisted reproductive treatments. The purpose of this study was to evaluate the effectiveness of a novel ovarian stimulation protocol based on the combination of corifollitropin-alfa plus five days of letrozole in E-NOR women undergoing IVF as compared with a daily recombinant-FSH regimen. Methods: We conducted a retrospective-controlled study on 182 couples undergoing their first IVF attempt. In Group A (experimental), letrozole (2.5 mg daily) was administered from day 2 (up to day 6 of the cycle), followed by corifollitropin-alfa on day 3 and daily recombinant FSH from day 10. In Group B, recombinant FSH from day 2 were administered (150 IU-225 IU daily). Statistical analysis was completed using SPSS Statistics. The primary outcome was the total number of MII oocytes retrieved. Results: Group A showed similar results compared to Group B in terms of MII oocytes, live birth, implantation, and clinical pregnancy rates (p = ns). Nevertheless, the experimental group was associated with a trend towards a higher number of developing follicles, total oocytes, and embryos (p < 0.05) with lower estradiol and progesterone values at ovulation induction compared to Group B, resulting in an increased chance of performing a fresh embryo transfer (p < 0.05). Conclusions: The combination of CFα plus five days of letrozole was associated with a trend towards a higher number of developing follicles, total oocytes, and obtained embryos. Moreover, the experimental protocol resulted in lower estradiol and progesterone values at ovulation induction compared to daily rFSH, with an increased chance of performing a fresh embryo transfer (with no OHSS occurrence). Given the observational design of our study, further well-conducted RCTs are needed.

The Effect of In Vitro Maturation (IVM) Protocol Changes on Measures of Oocyte/Embryo Competence

Purpose: In vitro maturation (IVM) continues its evolution as new ideas are introduced with the objective of making the IVM procedure easier and more effective. This study combines ideas believed likely to improve the IVM outcome or make the IVM oocyte identification process easier. Methods: A cohort of 45 women underwent an IVM cycle in which letrozole was used with the theoretical objective of improving the competence of small antral follicles, the oocyte aspiration technique was modified to minimize the time between oocyte aspiration and oocyte identification, and blastocysts were transferred during a subsequent cycle with controlled endometrial development. Results: Measures of oocyte competence used for these prospectively followed cycles were as follows: the maturation rate was 90.5%, the fertilization rate was 92.4%, the cleavage rate was 94.6%, the usable blastulation rate per zygote was 50.2%, and the implantation rate was 34.2%. Per transfer, the biochemical pregnancy rate was 63.2%, the clinical pregnancy rate was 55.3% and the ongoing/delivered pregnancy rate at the end of the first trimester was 47.4%. The miscarriage rate for clinical pregnancies in the first trimester was 14.3% and the ongoing twinning rate was 11.1%.

Effects of letrozole co-treatment on the cumulative live-birth rate among normal responders in gonadotropin-releasing hormone antagonist cycles

Studies have shown that letrozole cotreatment can improve clinical outcomes in high and poor responders in GnRH-antagonist protocol. However, whether letrozole is also beneficial to normal responders is not known. To investigate the clinical value of letrozole cotreatment during ovarian stimulation in vitro fertilization for normal ovarian reserve patients who were treated with the GnRH antagonist protocol, we conducted a retrospective study that based data from 1 January to 31 December 2017 for all IVF-ICSI GnRH-antagonist protocols. A total of 252 women who aged <40 years, FSH <10 IU/L on day 3 and antral follicle counting (AFC) >6 were included in the analysis (96 in the letrozole group and 156 in the no-letrozole group). The cumulative live-birth rate was calculated as the first live birth achieved after all cycles having an embryo transfer (cycles using fresh embryos and frozen-thawed embryos) among both groups. The initial gonadotropin (Gn) dosage and total Gn dosage were significantly lower and the number of days of Gn treatment was significantly fewer in the letrozole group than the non-letrozole group (p < 0.05). There were also significant between-group differences in luteinizing hormone, estradiol, and progesterone concentrations; and the number of metaphase II oocytes on the day of human chorionic gonadotropin treatment (p < 0.05). There was a significant difference in the implantation rate between the two groups that the letrozole group higher than the non-letrozole group (39.79 vs. 27.96%, p = 0.006), but there was no significant difference in the cumulative live-birth rate. The combination of letrozole with a GnRH antagonist may have no effect on the clinical pregnancy rate or cumulative live-birth rate in patients with a normal ovarian reserve. However, letrozole may increase the rate of embryo implantation and may reduce the requirement for exogenous gonadotrophins and, consequently, the cost of an IVF treatment cycle. In addition, the decreased estradiol level in the ovarian simulation by letrozole supports letrozole can be a safe solution for fertility preservation in estrogen-related cancer patients.