International Non-selection Study for ERA® Test in Patients with Previous Implantation Failures

Endometrial receptivity takes place in a self-limited period of time during the endometrial mid-secretory stage. This period, named as window of implantation (WOI), is modulated by molecular changes allowing embryo implantation. The Igenomix group developed a molecular tool able to classify the endometrium based on its transcriptomic profile, the Endometrial Receptivity Analysis (ERA®). This molecular tool analyzes, by next generation sequencing (NGS), the expression of 248 genes related to implantation, coupled to a computational predictor, to identify the specific transcriptomic profile for each endometrial phase. This test has been applied clinically since 2010 to improve clinical implantation, helping to synchronize a viable embryo with a receptive endometrium through the personalized embryo transfer (pET).

Apart from receptivity, there are other approaches to study the impact of the endometrial factor in infertility. One of those is the analysis of the endometrial microbiome (set of microorganisms that live in the endometrium). A reduced presence of certain beneficial microorganisms (mostly, bacteria of the genus Lactobacillus) or even the presence of a pathogenic microbiota in the endometrium could be associated with worse reproductive outcomes, affecting embryo implantation, pregnancy and consequently reducing the number of births. Igenomix has also developed the Endometrial Microbiome Metagenomic Analysis (EMMA®) as a diagnostic method to assess the microbiome content of the endometrium. Both, ERA® and EMMA® analyses, can be performed with a single endometrial tissue sample collected when maximum receptivity is commonly expected.

The main questions this study aims to answer are:

1. If a pET in a specific receptive endometrial transcriptomic profile is related to a higher Ongoing Pregnancy Rate (OPR) (≥ 12 gestational weeks; fetal heartbeat diagnosis) in patients with at least one previous implantation failure. This may help to fine-tune the ERA computational analysis for some specific endometrial receptivity profiles.

2. To identify new potential biomarkers and other factors that, if related with the WOI, could help to predict an optimal embryo implantation.

Once the study is approved by the competent Research Ethics Committee of each center, the recruitment and selection of patients will follow. Every potential participant will be asked to sign the study informed consent. To comply with the study design and the proposed hypothesis, a total number of 738 patients has been estimated, considering a 30% dropout rate.

This is a multicenter, international, competitive, non-selection (prospective cohort) study designed with two phases:

• Non-selection phase (double-blinded design). Participants will follow their previously programmed IVF/ICSI treatment and the resulting embryo/s will be tested for chromosomic anomalies with the Preimplantation Genetic Testing for Aneuploidies (PGT-A) at Igenomix. When at least one euploid/low-range mosaic blastocyst is reported, the patient will be scheduled for the only additional visit related to the study to collect the endometrial fluid and biopsy samples that will be used to determine the patient's WOI (ERA®) and endometrial microbiome (EMMA®). The results of neither of the tests will be disclosed to the patient or the doctor. Therefore, regardless of the endometrial status, the patient will follow the pre-established schedule for a subsequent regular frozen embryo transfer (FET) within the standard WOI (after 120±6 hours of progesterone exposure) in a hormone replacement therapy (HRT) cycle. After the FET, participants will be followed up as routine by their gynecologist.

• Rescue phase (open design). The ERA® test result may be disclosed, under request, to those patients who did not achieve an ongoing pregnancy on the non-selection phase. These results could guide a subsequent personalized euploid/low-range mosaic blastocyst transfer (pET) in a new HRT cycle, when the patient is most receptive.

Data exported from the medical records and source documents will be duly codified to protect the clinical and personal information of patients in accordance with the current legislation on data protection. This information will be exported to an electronic Case Report Form (eCRF). An interim data analysis will be carried out once the 30% of the embryo transfers corresponding to the non-selection phase is achieved. It will help us to assess the enrollment rate, protocol compliance and an early evaluation of the study objectives.

Patient´s participation will comprise an estimated total time of up to 18 months, corresponding to 1 month for the stimulation cycle and PGT-A, 1-2 months for endometrial samples collection, 1-2 months for the embryo transfer and up to 13 months to follow-up the clinical outcomes.