Immunomodulation for unexplained recurrent implantation failure: where are we now?

In brief: Immune dysfunction may contribute to or cause recurrent implantation failure. This article summarizes normal and pathologic immune responses at implantation and critically appraises currently used immunomodulatory therapies. Abstract: Recurrent implantation failure (RIF) may be defined as the absence of pregnancy despite the transfer of ≥3 good-quality blastocysts and is unexplained in up to 50% of cases. There are currently no effective treatments for patients with unexplained RIF. Since the maternal immune system is intricately involved in mediating endometrial receptivity and embryo implantation, both insufficient and excessive endometrial inflammatory responses during the window of implantation are proposed to lead to implantation failure. Recent strategies to improve conception rates in RIF patients have focused on modulating maternal immune responses at implantation, through either promoting or suppressing inflammation. Unfortunately, there are no validated, readily available diagnostic tests to confirm immune-mediated RIF. As such, immune therapies are often started empirically without robust evidence as to their efficacy. Like other chronic diseases, patient selection for immunomodulatory therapy is crucial, and personalized medicine for RIF patients is emerging. As the literature on the subject is heterogenous and rapidly evolving, we aim to summarize the potential efficacy, mechanisms of actions and side effects of select therapies for the practicing clinician.

Intravenous immunoglobulin for patients with unexplained recurrent implantation failure: a 6-year single center retrospective review of clinical outcomes.

The effectiveness of intravenous immunoglobulin (IVIg) for patients with unexplained recurrent implantation failure (uRIF) remains debated. We retrospectively analysed outcomes of uRIF patients treated with IVIg compared to a separate control uRIF cohort within our center (01/2014-12/2021). Primary outcomes included live birth, miscarriage, or transfer failure. We documented IVIg side effects and maternal/fetal outcomes. Logistic regression analysis was used to assess for association of IVIg exposure with outcomes and adjust for confounders. The study included 143 patients, with a 2:1 ratio of controls to patients receiving IVIg treatment. Patient characteristics were similar between groups. There was higher live birth rate (LBR) in patients receiving IVIg (32/49; 65.3%) compared to controls (32/94; 34%); p < 0.001). When stratifying patients into moderate and severe uRIF (respectively 3-4 and [Formula: see text] 5 previous good quality blastocyst transfer failures), only patients with severe uRIF benefited from IVIg (LBR (20/29 (69%) versus 5/25 (20%) for controls, p = 0.0004). In the logistic regression analysis, IVIg was associated with higher odds of live birth (OR 3.64; 95% CI 1.78-7.67; p = 0.0004). There were no serious adverse events with IVIg. IVIg can be considered in well selected patients with [Formula: see text] 5 previous unexplained, high quality blastocyst transfer failures. A randomized controlled trial is needed to confirm these findings.

450 IU versus 600 IU gonadotropin for controlled ovarian stimulation in poor responders: a randomized controlled trial.

OBJECTIVE: To compare the outcomes of controlled ovarian stimulation/in vitro fertilization cycles using 450 IU and 600 IU gonadotropin per day in women at risk of poor ovarian response. DESIGN: Prospective randomized controlled nonblinded study. SETTING: University-affiliated private IVF center. PATIENT(S): Women considered to be at risk of poor ovarian response: aged <41 years with basal FSH >10 IU/L, antimüllerian hormone <1 ng/mL, antral follicle count ≤ 8, or a previous IVF cycle with ≥ 300 IU/d gonadotropin that resulted in a cancellation, <8 follicles, or <5 oocytes. INTERVENTION(S): A total of 356 patients underwent a microdose GnRH agonist flare-up IVF/intracytoplasmic sperm injection protocol with a fixed daily dose of either 450 IU FSH (n = 176) or 600 IU FSH (n = 180) equally divided between Menopur and Bravelle. MAIN OUTCOME MEASURE(S): Number of mature oocytes retrieved. RESULT(S): The two groups were similar in terms of age, ovarian reserve, cause of infertility, duration of stimulation, and cycle cancellation rate. There were no significant differences in the number of metaphase II oocytes retrieved (4 [range 0-6] vs. 4 [range 2-7]), fertilization rate (62.4% vs. 57.0%), biochemical pregnancy rate (20.5% vs. 22.9%), clinical pregnancy rate (16.4% vs. 18.3%), and implantation rate (29.8% vs. 30.4%) between the 450 IU and 600 IU groups, respectively. CONCLUSION(S): Gonadotropin of 600 IU/d does not improve outcome of IVF cycles compared with 450 IU/d in women at risk of poor ovarian response. CLINICAL TRIAL REGISTRATION NUMBER: NCT00971152.