Response to editorial entitled “Biomarkers of endometrial receptivity through a minimally invasive approach”

30 05 2013

To the Editor:

The editorial by Dr. Robert Norman in this issue of Fertility and Sterility (1) succinctly summarizes the various approaches currently used to identify biomarkers of endometrial receptivity toward development of a viable predictive/assessment test for clinical application. As Dr. Norman points out, multiple approaches have been applied to identify candidate biomarkers, including proteomic and lipidomic assessments of uterine aspirate fluid and gene expression profiling of endometrial biopsies. In this editorial, Dr. Norman introduces our paper in which we demonstrate the feasibility of performing genome-wide gene expression profiling on uterine aspirations (2). Using unsupervised hierarchical clustering, we demonstrate that the phase of sampling (LH+2 versus LH+7) affects gene expression more so than individual differences in gene expression between patients. We identified and verified robust differences in expression of 245 genes due to phase of sampling and determined that expression of 53 of these genes efficiently separated our two groups and those of a publically available dataset of gene expression signatures obtained from endometrial biopsy samples. Since LH+2 coincides with a pre-receptive phase and LH+7 coincides with a receptive phase in fertile women, the differentially expressed genes identified in our study encode for candidate biomarkers of endometrial receptivity. This 53-gene list overlaps significantly with those indicated in other studies, including the 238-gene list comprising the endometrial receptivity assay used by Diaz-Gimeno et al. (3) in their algorithm for predicting the receptive period from endometrial biopsy samples. We are excited by the potential of our approach because uterine aspiration is less traumatic to the endometrium than biopsy. Unlike endometrial biopsy, uterine aspiration is compatible with evaluation within an active IVF or natural cycle in which a patient is attempting pregnancy (4, 5), enabling us and other researchers to directly associate altered gene expression with implantation success. This approach will facilitate our future identification of those candidate biomarkers for further development of point-of-care assays for clinical use. While our 53-gene cassette includes several interesting candidate biomarkers, including those encoding secreted products, we do not propose these as a clinical test. Rather, we propose that our approach enables further testing and reduction of this signature to identify those genes most predictive. We agree with Dr. Norman that protein-based assays will be preferable to transcript measurements for clinical assays; however, gene expression data are necessary to direct proteomic discovery assays to improve these approaches. Read the rest of this entry »

Have antimüllerian hormone and antral follicle count been given the same opportunities?

30 05 2013

To the Editor:

We read with great interest the paper “Antimüllerian hormone in gonadotropin releasing-hormone antagonist cycles: prediction of ovarian response and cumulative treatment outcome in good-prognosis patients” (1) by Arce et al. In that paper the authors make a secondary analysis of the MEGASET study, concluding that antimüllerian hormone (AMH) can predict oocyte yield, categories of ovarian response, and live birth from IVF, and that AMH was associated with these outcomes, irrespective of the type of gonadotropin used. Moreover, as Nelson pointed out in the same issue of the journal (2), in Arce and colleagues’ analysis it was observed that the antral follicle count (AFC) was not associated with any of these outcomes.

There are two aspects that we would like to comment on. First, as already mentioned by Nelson, previous studies have observed that AMH and AFC were essentially equivalent in ovarian response prediction. We recently analyzed our population of oocyte donors (3) that presented similar inclusion criteria to that of the study by Arce (1): normal ovarian reserve (OR) by AFC and basal follicle-stimulating hormone (FSH). In this population treated with antagonists, AMH levels (analyzed by the Gen 2 ELISA) correlated significantly with the number of metaphase II oocytes (MII) retrieved. The AMH cutoff to predict a retrieval <6 MII was 2.31 ng/ml. AMH showed a mild capacity to discriminate poor response (AUC 0.675). We carried out a multiple regression analysis including age, AFC, and FSH in order to obtain a poor ovarian response prediction model and the AUC was 0.668 (95 % CI 0.540-0.796); if AMH was added to the model, the AUC was 0.713 (95% CI 0.596-0.830), slightly improving the prediction capacity. According to our results, measuring AMH is not an advantage for those reproductive medicine centers with easy access to AFC and FSH. In Arce’s paper, blood samples were analyzed at a central laboratory, whereas the AFC was performed at each investigational site by different observers, and a sonographer-dependent variability has been suggested. Read the rest of this entry »

Is universal application of blastocyst biopsy with comprehensive chromosome screening for embryo selection ready for prime time?

29 05 2013

To the Editor:

We read with great interest the article by Scott and colleagues, “Blastocyst biopsy with comprehensive chromosome screening and fresh embryo transfer significantly increases IVF implantation and delivery rates: a randomized controlled trial” (1). This is the highly anticipated third study of a planned three-phase initial strategy designed to validate the use of the authors’ rapid qPCR-based comprehensive chromosome screening (CCS) technology for embryo screening and selection.

In the first of the three studies, validation of the technology was confirmed using cell lines and discarded blastocysts of previously confirmed ploidy status (either aneuploid or euploid) (2). In the second study, the technology was shown to have a high negative predictive value (NPV, failure to deliver when aneuploid embryos were transferred) of 96% albeit the positive predictive value (PPV, delivery per euploid embryo transferred) was considerably lower at 41.4% (3). In this, the third, study comprising a randomized controlled trial (RCT) to assess clinical utility of CCS, results showed that use of CCS resulted in impressively high implantation and delivery rates (79.8% and 84.7%, respectively) which were, indeed, both significantly greater than those obtained from embryos transferred after morphological evaluation alone (63.2% and 67.5%).

We appreciate the forward-thinking approach of the investigators in their systematic approach to validate and then assess efficacy of the technology for embryo screening and selection. However, we would like to raise some queries regarding the results reported, as well as discuss several limitations of this study. Read the rest of this entry »

The nasal epithelium provides an easier alternative than the oviduct for the study of ciliary beating

3 05 2013

To the Editor:

Our group thanks Dr. Maruyama (1) for his positive comments on our paper “Decreases in adrenomedullin expression and ciliary beat frequency in the nasal epithelium in tubal pregnancy.” In this study, we were inspired by our collaborators. We found that the nasal cilia beat frequency reported by Ho et al. (2) was similar to that observed by us in the oviduct. If the cilia at the two different sites behave similarly, the nasal cilia sampling can perhaps provide an easier alternative when we have great difficulties in getting oviductal tissues.

We would like to elaborate on Dr. Maruyama’s comments that it remains uncertain whether or not the plasma ADM level independently determines tubal ciliary activity. We wish to stress that it is the oviductal tissue adrenomedullin (ADM) level that is important. Plasma ADM level only serves as an indirect indicator of ciliary activity on the assumption that the decrease in oviductal ADM level is reflected in the plasma. The oviductal ADM level is dependent on the hormone environment but the effect of ADM is probably direct and not via the steroid hormones, which will take a much longer time to act than ADM. Another way whereby estrogen and progesterone may mediate the ADM effect is via the ADM receptors. Progesterone has been reported to increase calcitonin gene-related peptide (CGRP) and ADM receptors in the rat uterus (3). However, if ADM is deficient, any up-regulation of the receptors is perhaps not important. Read the rest of this entry »