Fetal and Maternal Safety Considerations for In Utero Therapy Clinical Trials: iFeTiS Consensus Statement

High-resolution ultrasound scanning and rapid advances in prenatal genetics enabled the diagnosis of life-threatening and severe congenital disorders early in gestation. In utero interventions with advanced therapy products, such as gene or stem cell transplantation, hold great promise to ameliorate in utero damage, induce immune tolerance, and improve outome. In utero treatment must not only present advantages over postnatal treatment but also offer a favorable risk/benefit balance for both mother and fetus. In utero application of stem cells and proteins has already happened on a case-by-case basis and clinical trials of in utero stem cell transplantation (IUSCT) have begun. The International Fetal Transplantation and Immunology Society (IFeTIS; https://www.fetaltherapies.org) facilitated a panel discussion of international experts in 2019 to define best practice and consider the key safety aspects of such clinical trials, including recommendations for patient monitoring and managing ethical dilemmas. In utero stem cell transplantation and protein therapies are now entering collaborative clinical trials. A trial of in utero hematopoietic stem cell (HSC) transplantation for fetuses with alpha thalassemia major has reported the successful birth of the first two participating infants (https://fetus.ucsf.edu/node/406). Here, bone marrow HSCs retrieved from the mother during pregnancy are used for transplantation; these are delivered once during the pregnancy, coinciding with an ultrasound-guided intrauterine blood transfusion for fetal anemia. Based on promising results from individual compassionate cases,1Götherström C. Westgren M. Shaw S.W.S. Aström E. Biswas A. Byers P.H. Mattar C.N. Graham G.E. Taslimi J. Ewald U. et al.Pre- and postnatal transplantation of fetal mesenchymal stem cells in osteogenesis imperfecta: a two-center experience.Stem Cells Transl. Med. 2014; 3: 255-264Crossref PubMed Scopus (116) Google Scholar the BOOSTB4 clinical trial of postnatal or pre- and postnatal mesenchymal stem cell (MSC) transplantation for severe osteogenesis imperfecta (OI) has received regulatory and ethical approval in Sweden and the UK and has treated three postnatal referrals in Sweden (https://www.boostb4.eu/). First trimester human fetal liver-derived MSCs are administered once under ultrasound guidance into the umbilical vein, with postnatal booster doses after birth. Intra-amniotic administration of a recombinant ectodysplasin A protein for in utero prevention of X-linked hypohidrotic ectodermal dysplasia (XLHED) also looks promising. In three affected infants treated in utero at 26 weeks gestation, now between 3 and 4 years old, no ectodermal dysplasia-related illnesses have been observed. The children are able to sweat normally, in contrast to untreated XLHED-affected children who do not sweat.2Schneider H. Faschingbauer F. Schuepbach-Mallepell S. Körber I. Wohlfart S. Dick A. Wahlbuhl M. Kowalczyk-Quintas C. Vigolo M. Kirby N. et al.Prenatal Correction of X-Linked Hypohidrotic Ectodermal Dysplasia.N. Engl. J. Med. 2018; 378: 1604-1610Crossref PubMed Scopus (59) Google Scholar Regulatory and ethical applications for a pivotal clinical trial are in development. The requirements for optimal assessment of safety for in utero interventions are becoming clear through discussions of clinical trial protocols with regulatory and ethical authorities during scientific advice and approvals. Safety evaluations must consider the risks of both the mode of administration and the product itself to the fetus and the mother. Monitoring strategies aimed at detecting potential adverse events have been developed. Minimally invasive, ultrasound-guided injection into the umbilical vein is being used in currently approved IUSCT clinical trials. Technically, IUSCT via umbilical vein injection is similar to fetal blood transfusion, a procedure performed worldwide for decades. In a series of 937 fetal blood transfusions for fetal anemia (2001–2015), there was, per procedure, a 1.2% complication risk and a 0.6% rate of fetal loss.3Zwiers C. Lindenburg I.T.M. Klumper F.J. de Haas M. Oepkes D. Van Kamp I.L. Complications of intrauterine intravascular blood transfusion: lessons learned after 1678 procedures.Ultrasound Obstet. Gynecol. 2017; 50: 180-186Crossref PubMed Scopus (53) Google Scholar Notably, these procedures were performed in anemic fetuses. The risk of complications may be even lower when the fetal circulation is accessed in fetuses without anemia or before manifestation of other congenital pathology. Fetal blood transfusion complications include emergency Caesarean section (0.4%), fetal bradycardia (0.3%), preterm rupture of the membranes (0.1%), infection (0.1%), and preterm birth (0.1%).3Zwiers C. Lindenburg I.T.M. Klumper F.J. de Haas M. Oepkes D. Van Kamp I.L. Complications of intrauterine intravascular blood transfusion: lessons learned after 1678 procedures.Ultrasound Obstet. Gynecol. 2017; 50: 180-186Crossref PubMed Scopus (53) Google Scholar Having experienced operators perform the transfusion, administering fetal paralysis, and avoiding administration into free umbilical cord loops reduces the complication rate.3Zwiers C. Lindenburg I.T.M. Klumper F.J. de Haas M. Oepkes D. Van Kamp I.L. Complications of intrauterine intravascular blood transfusion: lessons learned after 1678 procedures.Ultrasound Obstet. Gynecol. 2017; 50: 180-186Crossref PubMed Scopus (53) Google Scholar The risk of fetal bleeding falls almost 40-fold by accessing the umbilical vein within its transit of the fetal liver as compared to cordocentesis.4Aina-Mumuney A.J. Holcroft C.J. Blakemore K.J. Bienstock J.L. Hueppchen N.A. Milio L.A. Crino J.P. Intrahepatic vein for fetal blood sampling: one center’s experience.Am. J. Obstet. Gynecol. 2008; 198: 387.e1-387.e6Abstract Full Text Full Text PDF Scopus (10) Google Scholar Avoiding transplacental needling decreases the risk of fetal-maternal bleeding 4-fold. This is an important consideration in IUSCT with cells from a non-maternal donor to reduce maternal exposure to the advanced therapy product. The iFetis panel recommended that the targeted primary intravascular injection site for IUSCT was the intrahepatic umbilical vein. Ultrasound-guided intraperitoneal injection and intracardiac injection are alternative systemic routes of delivery that have been safely used in individual cases of IUSCT. Ultrasound-guided administration of recombinant proteins or enzymes to correct metabolic disorders are likely to carry similar procedural risks. For XLHED, which requires intra-amniotic administration of medication, the complications are likely to be similar to those of ultrasound-guided amniocentesis, a commonly performed prenatal diagnostic procedure, although the risk of this procedure is not actually known. A recent meta-analysis found the risk of pregnancy loss following amniocentesis at 15–24 weeks to be around 0.11%.5Akolekar R. Beta J. Picciarelli G. Ogilvie C. D’Antonio F. Procedure-related risk of miscarriage following amniocentesis and chorionic villus sampling: a systematic review and meta-analysis.Ultrasound Obstet. Gynecol. 2015; 45: 16-26Crossref PubMed Scopus (406) Google Scholar Any invasive procedure in pregnancy carries a risk of materno-fetal transfer of infectious disease. Transmission of hepatitis B virus to the fetus after amniocentesis in women who are carriers is low; there is no evidence that transmission of hepatitis C is increased following amniocentesis in seropositive mothers. Likewise, the rate of transmission of HIV in women on highly active antiretroviral therapy (HAART) undergoing amniocentesis is similar to HIV-positive women who do not undergo invasive prenatal diagnosis.6Somigliana E. Bucceri A.M. Tibaldi C. Alberico S. Ravizza M. Savasi V. Marini S. Matrone R. Pardi G. Italian Collaborative Study on HIV Infection in PregnancyEarly invasive diagnostic techniques in pregnant women who are infected with the HIV: a multicenter case series.Am. J. Obstet. Gynecol. 2005; 193: 437-442Abstract Full Text Full Text PDF PubMed Scopus (42) Google Scholar For diagnostic or therapeutic invasive procedures other than amniocentesis, there are little data on the risk of vertical transmission of hepatitis B, hepatitis C, or HIV, and patients should be counselled to this effect prior to their use.7Gagnon A. Davies G. Wilson R.D. GENETICS COMMITTEEPrenatal invasive procedures in women with hepatitis B, hepatitis C, and/or human immunodeficiency virus infections.J. Obstet. Gynaecol. Can. 2014; 36: 648-653Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar Particularly in IUSCT, the potential of fetal/neonatal liver damage due to active hepatitis or immune downregulation from active HIV infection is important. Excluding women positive for hepatitis and HIV infection from current IUSCT clinical trial protocols seems sensible until specific risk/benefit information is available. For patients undergoing HSC transplantation with maternal cells (such as in the ongoing University of California, San Francisco [UCSF] clinical trial for alpha thalassemia), standard donor criteria also mandate exclusion of such patients. To reduce maternal and fetal pain or discomfort, the procedure is performed under local anesthetic, and similar needling procedures for fetal blood transfusion are generally well tolerated. Severe maternal complications, such as maternal bowel injury, are uncommon probably because the procedure is ultrasound guided (<0.1%).8Royal College of Obstetricians & Gynaecologists. (2006). Amniocentesis (Consent Advice No 6). Published online May 1, 2006. https://www.rcog.org.uk/en/guidelines-research-services/guidelines/consent-advice-6/Google Scholar, 9Royal College of Obstetricians & GynaecologistsAmniocentesis and Chorionic Villus Sampling (Green-top Guideline No. 8).2010https://www.rcog.org.uk/en/guidelines-research-services/guidelines/gtg8/Google Scholar Maternal deaths are rarely reported after amniocentesis and are mainly associated with Escherichia coli bacterial infection. As in utero drug product interventions administer only a small volume of stem cells or protein, procedures are short, lasting only a few minutes. Recovery time will not be prolonged, and venous thromboembolism secondary to immobility is unlikely to occur. Maternal exposure to fetal or donor antigens may cause sensitization. Development of red cell antigens could place future pregnancies at risk of hemolytic disease of the newborn and affect maternal blood transfusion. Rho(D) globulin should be given to the 15% of pregnant women who are Rhesus blood group-negative to reduce sensitization risk to 0.35%.13Antiel R.M. Halpern S.D. Stevens E.M. Vrecenak J.D. Patterson C.A. Tchume-Johnson T. Smith-Whitley K. Peranteau W.H. Flake A.W. Barakat L.P. Acceptability of In Utero Hematopoietic Cell Transplantation for Sickle Cell Disease.37. 2017: 914-921Google Scholar Sensitization to other red cell antigens is rare. While the risks associated with the product administered will depend upon the exact therapeutic agent, the iFetis panel agreed common considerations for targeted monitoring strategies. Immune, allergic, or toxic reactions to the therapeutic product or a component part involved in its manufacture warrant monitoring. And despite extensive microbiological testing and production in accordance with good manufacturing practice, an advanced therapy drug product could theoretically transmit an infectious disease from the donor or itself could be a source of microbiological contamination. Ectopic tissue formation is a specific potential risk often considered with MSC administration. A recent meta-analysis of randomized controlled trials of adult and childhood MSC transplantation did not observe acute toxicity, organ system complications, infection, death, or malignancy; the only significant association detected was transient fever.10Pilgrim H. Lloyd-Jones M. Rees A. Routine antenatal anti-D prophylaxis for RhD-negative women: a systematic review and economic evaluation.Health Technol Assess. 2009; 13 (iii, ix–xi): 1-103Crossref PubMed Scopus (51) Google Scholar The specific risks of postnatal HSC transplantation are related to the pre-transplant ablative conditioning. This has not been used in IUSCT cases or in the current alpha thalassemia trial. Graft-versus-host disease remains a potential complication, but the tolerogenic environment of the fetal immune system is believed to increase the threshold for this complication. Where the mother is the stem cell donor, HSC collection from the maternal bone marrow is associated with additional minor maternal risks, such as those due to spinal anesthesia and maternal anemia. Given the small size of the fetus, only low volumes of maternal bone marrow are required, which makes the chance of maternal anemia less likely. Paternal bone marrow or a related donor are alternative donors. Adverse events are most likely to occur short-term following fetal injection. The iFetis panel recommended inpatient monitoring of both mother and fetus for 24 h to enable detection of both procedure-related complications and toxic or allergic reactions to the drug product administered. Fetal monitoring would be similar to that recommended after standard fetal needling procedures. This includes ultrasonographic visual assessment throughout and immediately following the procedure to enable timely action, such as intracardiac resuscitation. If a suitable gestational age has been reached, emergency Caesarean delivery may be indicated should a prolonged fetal bradycardia occur. In late gestation, uterine tocodynamometry with fetal cardiotocography (CTG) should be performed following IUSCT to confirm fetal wellbeing. CTG interpretation in the preterm fetus with congenital disease is difficult due to the lack of standard evaluation criteria, and CTG monitoring plans will need to be individualized. Fetal ultrasound assessment should be performed before hospital discharge to assess fetal hemorrhage, effusions, and hydrops, with Doppler evaluation of fetal middle cerebral and umbilical arteries for vascular perfusion and fetal anemia. A detailed protocol for examination and analysis of the fetus or neonate and placenta is vital if perinatal loss occurs. Adverse event reporting should use the maternal and fetal criteria defined in the Medical Dictionary of Regulatory Activities (MedDRA; https://www.meddra.org). A Delphi consensus for grading maternal and fetal adverse events is shortly to be available, with neonatal adverse event criteria and grading provided by National Cancer Institute International Neonatal Consortium (INC) terminology. Admission for routine maternal and fetal monitoring in the absence of pathology is common in pregnancy and should not be documented as an adverse event. Regular follow-up is mandatory with ultrasound examination to assess fetal growth and wellbeing, fetal Doppler blood flow, organ-specific growth and echotexture, and examination of the pregnant woman for side effects. The timing and mode of delivery, such as Caesaean section after in utero therapy, should depend on the underlying fetal congenital disorder. Umbilical cord blood can be collected at birth for fetal biochemistry, immune reaction to the therapeutic products, cell engraftment, donor-specific immune tolerance, and expression of the target protein. Often pregnancies affected by severe life-threatening congenital disease deliver spontaneously preterm, and this should be anticipated. Long-term follow-up of the treated neonate will depend upon the underlying congenital condition and should be planned carefully. Maternal health should also be monitored postpartum to collect information on adverse events. Current clinical trials require long-term follow-up of both mother and infant, for example 10 years in the BOOSTB4 trial; a registry of in utero therapy interventions is under consideration. A maternal peripheral blood sample allows for engraftment studies if the donor was not the mother herself. Testing for donor-specific antibody formation may inform about the maternal immune response to the cell product. Further maternal long-term data collection should coincide with longitudinal neonatal monitoring. Based on outcomes of pregnancies after amniocentesis or cord blood transfusion, it is not expected that future pregnancies will be adversely affected by these minimally invasive fetal interventions. The proposed fetal interventions for cellular, protein, and gene therapies are far less invasive than open fetal surgery, for example, where high live birth rates in subsequent pregnancies are seen. But while IUSCT is less invasive, the risks from the proposed interventions will relate to the drug rather than the procedure. Safety should be the primary outcome of initial clinical trials, and the wellbeing of all participants (maternal, fetal, cell donor) must be considered. Counseling must be non-directive, in which the options of no intervention versus the experimental intervention—with all possible risks and benefits—are explained without personal bias. The language used to describe the clinical trial must be carefully considered, using the terms “intervention” rather than “therapy.” An independent healthcare professional or patient advocate to review patient understanding will reassure that the patient or couple are not under a “therapeutic misconception” but appreciate the experimental nature of the proposed intervention. The potential for a lethal disorder to be partially treated, resulting in survival of a neonate with an extremely poor quality of life, is highly relevant to informed consent discussions. Paternal consent and the role of the father in the ongoing care of a neonate treated as a fetus are also important.11Lalu M.M. McIntyre L. Pugliese C. Fergusson D. Winston B.W. Marshall J.C. Granton J. Stewart D.J. Canadian Critical Care Trials GroupSafety of cell therapy with mesenchymal stromal cells (SafeCell): a systematic review and meta-analysis of clinical trials.PLoS One. 2012; 7: e47559Crossref PubMed Scopus (683) Google Scholar Interventions that are commenced in utero with a further postnatal application, for example. a postnatal stem cell booster, will require reconfirmation of parental consent after birth to allow ongoing neonatal participation in the clinical trial. iFetis panel members endorsed engagement with stakeholder and patient groups for development and ongoing conduct of clinical trials of in utero therapy. Patient groups have provided input during protocol development, including acceptability and ethical considerations of the proposed interventions, inclusion and exclusion criteria, participant monitoring, and outcome measures.12Johansson M. Hermerén G. Sahlin N.-E. Paternal consent in prenatal research: ethical aspects.Med Heal Care Philos. 2020; 23: 325-331Crossref PubMed Scopus (2) Google Scholar, 14Sheppard M. Spencer R.N. Ashcroft R. David A.L. EVERREST ConsortiumEthics and social acceptability of a proposed clinical trial using maternal gene therapy to treat severe early-onset fetal growth restriction.Ultrasound Obstet. Gynecol. 2016; 47: 484-491Crossref PubMed Scopus (28) Google Scholar, 15Hill M. Lewis C. Riddington M. Crowe B. DeVile C. David A.L. Semler O. Westgren M. Götherström C. Chitty L.S. Stakeholder views and attitudes towards prenatal and postnatal transplantation of fetal mesenchymal stem cells to treat Osteogenesis Imperfecta.Eur. J. Hum. Genet. 2019; 27: 1244-1253Crossref PubMed Scopus (9) Google Scholar They are also key to disseminating information about in utero trials to potential participants. In conclusion, newly approved clinical trials have highlighted important safety considerations to enable safe testing of these novel therapies. This consensus should allow in utero stem cell, protein, and, eventually, gene replacement/modification therapies to fulfil their great promise to treat many severe congenital diseases. Conceptualization, A.L.D., C.G., M.C., T.C.M., G.A.-P., and R.S.; Methodology, A.L.D. and R.S.; Investigation, A.L.D., C.G., A.J., T.C.M., G.A.-P., H.S., and R.S.; Writing – Original Draft, R.S. and A.L.D.; Writing – Review & Editing, G.A.-P., K.B., J.K.Y.C., M.C., C.G., A.J., T.C.M., C.M., C.D.P., W.H.P., H.S., S.W.S., S.N.W., and M.W.; Funding Acquisition, C.G., T.C.M., and H.S.; Resources, A.L.D., C.G., T.C.M., and H.S.; Supervision, A.L.D. H.S. holds a patent relevant to this publication (WO2015061302). A.L.D. has received consulting fees from the EspeRare foundation. All other declare no competing interests. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 681045 , the German Research Foundation (DFG; grant SCHN 569/4-1 to H.S.), and the German Federal Ministry of Education and Research (BMBF; grant 01KG2008 to H.S.). A.L.D. is supported by the National Institute for Health Research University College London Hospitals Biomedical Research Centre . S.N.W. received funding from MRC grants MR/R015325/1 , MR/N026101/1 , and MR/N026101/1 and NC3Rs grant NC/L001780/1 . G.A.P. and C.P. are supported by NHLBI grants HL130856 , HL135853 , and HL148681 . W.P. is supported by National Institutes of Health grants DP2HL152427 and 1R01DK123049-01 . C.G. and M.W. are supported by the Swedish Research Council ( 921-2014-7209 ). C.M. is funded by Singapore National Medical Research Council grant NMRC/CSA-INV/0012/2016 . S.W.S. is supported by Chang Gung Memorial Hospital CPRPG1J0021 . T.C.M. is supported by the California Institute for Regeneration Medicine . J.K.Y.C. is supported by Singapore Ministry of Health’s National Medical Research Council ( CSA-SI/008.2016 , CIRG/1484/2018 , and CIRG/1459/2016 ). H.S. is supported by the National Foundation for Ectodermal Dysplasias (NFED) and the German-Swiss-Austrian Ectodermal Dysplasia Patient Organization ; he also received research funding related to this project from Edimer Pharmaceuticals and the EspeRare Foundation . A.J., via the EspeRare foundation , has received philanthropic funding from the Dioraphte Foundation , Fondation Pictet , a Private Geneva Foundation , and a private donation.