PGT-A Versus Blastocyst Morphology Selection
Condition: Pregnancy
Study type: Interventional

Summary: 
      Introduction Embryo aneuploidy is likely the leading cause of implantation failure in IVF
      cycles. Since the inception of IVF, non-invasive morphology based scoring has been the most
      widely used embryo selection method, resulting in relatively low embryo implantation rates.
      Our understanding of the optimal conditions required for in vitro embryo culture in IVF has
      advanced significantly over the past two decades. The implementation of improved in vitro
      embryo culture technologies (i.e., culture media and incubators) has resulted in an increase
      in the number of good quality embryos and consequently in increased numbers of blastocysts.
      While blastocyst transfers have seemingly improved the reproductive outcomes of IVF, they
      still remain suboptimal. The main objective of this randomized controlled trial (RCT) will be
      to investigate whether preimplantation genetic testing (i.e., PGT with comprehensive
      chromosome screening (CCS)) for aneuploidy is a superior embryo selection method, with the
      live birth outcomes of euploid blastocyst frozen embryo transfers (FET) compared with the LB
      outcomes of unknown-ploidy blastocyst FET, with blastocysts selected on (standard)
      morphological score.

      Methods This RCT will be conducted at a single private IVF centre performing routine
      segmented-IVF, with intracytoplasmic sperm injection (ICSI), blastocyst freeze-all, and
      artificial frozen embryo transfer (art-FET). Normo-ovulatory infertile patients, with
      maternal age ≤35 years and at least two blastocysts with a morphology score of 2BB
      cryopreserved, will be randomized by computer-generated randomized allocation to either the
      PGT or morphology arm of the trial. All transfers will be single embryo transfers (SET), with
      only the first FET cycles following freeze-all to be analyzed.

      Consent and Ethics Akdeniz University Medical Faculty Clinical Research Ethics Committee has
      approved the trial (reference number: 2015/399), with anonymized results to be released in
      ClinicalTrials.gov. All patients will provide informed consent, which included an agreement
      for the use of anonymised data for research and SET.
    

Detailed description: 
      Introduction Embryo aneuploidy is likely the leading cause of implantation failure in IVF
      cycles. Since the inception of IVF, non-invasive morphology based scoring has been the most
      widely used embryo selection method, resulting in relatively low embryo implantation rates.
      Embryo morphology assessment methods have significant limitations (i.e., the assessments are
      subjective and the method uses fixed time-point assessments to define dynamic embryo
      development) and shortcomings (i.e., exposes embryos to sub-optimal conditions during
      assessment). Notwithstanding the limitations and shortcomings of this method its use
      worldwide has continued, because it is a relatively simple and non-invasive method and its
      scores have been shown to be (moderately) positively correlated to embryo euploidy, ongoing
      pregnancy, and live birth (Van Royen et al., 1999, Ahlstrom et al., 2011, Forman et al.,
      2013, Capalbo et al., 2014, Oron et al., 2014, Rhenman et al., 2015).

      However multiple gestations still represents one of the most significant complications in
      IVF, which are mainly the result of multiple-embryo embryo transfers, with multiple-embryo
      transfers used to overcome the relatively low embryo implantation rates in IVF. Our
      understanding of the optimal conditions required for in vitro embryo culture in IVF has
      advanced significantly in the past two decades. The implementation of improved in vitro
      embryo culture technologies (i.e., culture media and incubators) has resulted in an increase
      in the number of good quality embryos and consequently in the numbers of blastocysts. While
      blastocyst transfers have seemingly improved the reproductive outcomes in IVF, the use of SET
      and PGT technologies have revealed embryo implantation still to be sub-optimal (Schoolcraft
      et al., 2013). New CCS platforms are a major breakthrough in PGT, allowing 24-chromosome
      screening to be performed with high degree of accuracy from single cells (Harper and Harton,
      2010). The evidence that morphology scores were only moderately associated with euploidy and
      that the transfer of PGT predicted euploid embryos resulted in higher implantation rates
      (Dahdouh et al., 2015), has seen the continued use of morphology-based scoring methods
      increasingly being challenged.

      In addition to all the other advances in IVF, significant improvements have also been made in
      cryopreservation technologies. These improvements have resulted in significant improvements
      in frozen-thawed embryo survival (i.e. minimizing of risks), post-thaw developmental
      competence (Cobo et al., 2012; Balaban et al., 2008), and in the reproductive outcomes of FET
      (Evans et al., 2014; Ozgur et al., 2015). The benefits of FET include; the transfer of
      embryos to a more physiologic endometrium (i.e., early luteal phase), the ability to time
      transfers more accurately, and the ability to use patient-specific endometrial preparations
      (Casper and Yanushpolsky, 2016, Franasiak et al., 2016; Groenewoud et al., 2013, Yarali et
      al., 2016).

      Moreover, the hypotheses of PGT requires to be confirmed in further robust RCT before its
      implementation in routine IVF.

      Objectives The primary objective of this RCT will be to investigate whether PGT for
      aneuploidy as a blastocyst selection method is superior to standard morphology scoring
      blastocyst selection, comparing the reproductive outcomes in FET cycles. The decision to
      transfer all blastocysts in FET will eliminate any potential impact of ovarian stimulation
      confounding on endometrial receptivity and to use freeze-all cycles will allow the use of the
      primary blastocysts of blastocyst cohorts. The primary outcome measure of this trial will be
      LB, with a LB defined as a pregnancy cycle delivering at >20 weeks of gestation.

      Secondary objectives The secondary objective of the RCT will be to investigate whether
      euploid blastocyst transfer results in reduced miscarriage, with a miscarriage defined as a
      clinical pregnancy lost at <20 weeks of gestation.

      Keywords: blastocyst; comprehensive chromosome screening; euploidy; frozen embryo transfer
    

Intervention name(s): comprehensive chromosome screening
Intervention type(s): Procedure
Intervention description(s): Biopsy Blastocysts with morphological grades of ≥2BB will be biopsied on day 5 of in vitro embryo culture. Biopsies will be performed using a Hamilton Thorne Zilos laser (Hamilton Thorne, MA, USA), with 3-10 trophectoderm cells removed from the blastocysts.
Comprehensive chromosome screening All trophectoderm biopsies will be processed for analysis by Next-Generation Sequencing (NGS, Illumina, California, USA).
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: single-centre randomized controlled trial
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: morphological score; preimplantation genetic testing; frozen embryo transfer; blastocyst