Medical therapy to attenuate fetal anaemia in severe maternal red cell alloimmunisation

The Use of Novel Therapies in the Management of Haemolytic Disease of the Fetus and Newborn (HDFN): Scientific Impact Paper No. 75

Haemolytic disease of the fetus and newborn (HDFN) is a rare condition that causes a baby to develop anaemia while growing inside the woman; or after birth. Left untreated, this may lead to stillbirth or neonatal death. HDFN is caused when the pregnant woman's antibodies cross the placenta, enter the baby's circulation, and attach to proteins called antigens (inherited from the father) on the baby's haemoglobin containing red blood cells, and cause them to break apart, causing fetal anaemia. Women routinely have their blood tested at the start of pregnancy to assess their ABO blood group and Rh antigens. There are five main Rhesus antigens: D, C, c, E, e; with anti-D being responsible for most cases of HDFN. If a woman is found to be Rh D negative; a 'non-invasive' blood test is performed to assess if the fetal blood group is the same as the woman's. If a woman is found to be Rh D negative, and the baby is found to be D positive, the baby is at risk. This is because the baby has inherited the D antigen from the father; so-called Rhesus incompatibility. Other red blood cell antibodies such as anti-Kell or anti-Duffy can also cause fetal anaemia. Women at highest risk of developing HDFN are those who have had at least one previous birth or a sensitising event (such as abdominal trauma) in a current or previous pregnancy, causing the woman and baby's blood to mix. Current treatment for haemolytic disease of the fetus involves giving fetal blood transfusions, with a small risk of early labour or pregnancy loss. If anaemia develops later in pregnancy, early delivery of the baby may be recommended; which could lead to complications of prematurity. In cases of mild HDFN, the baby may only require light therapy for neonatal jaundice. However, if the anaemia occurs earlier in pregnancy and is severe, the baby may need blood transfusions while still in the womb - and after birth may require an exchange transfusion, to remove the woman's antibodies from their circulation and to treat the anaemia. Intravenous immunoglobulin (IVIG) is a potential non-invasive method to prevent or delay the onset of severe anaemia. It is a blood product given intravenously every week to women who have been deemed at very high risk of early onset HDFN. It can be started at the end of the first trimester until birth, or until anaemia develops. This paper will discuss the evidence behind IVIG and other novel therapies during pregnancy, including the risks and the benefits. The developers of the paper include obstetricians, neonatologists and haematologists to provide different opinions on this topic.

Screening of pregnant women for foetal neonatal alloimmune thrombocytopenia: A cost-utility analysis

BACKGROUND AND OBJECTIVES

Foetal and neonatal alloimmune thrombocytopenia (FNAIT) results from maternal platelet-directed antibodies and can result in severe intracranial haemorrhage (ICH) in foetuses and newborns. Screening for human platelet antigen-1a (HPA-1a)-directed antibodies during pregnancy could allow timely intervention with antenatal treatment and prevent ICH. We assessed the cost effectiveness of HPA-1a typing and anti-HPA-1a-screening as part of the prenatal screening programme.

MATERIALS AND METHODS

Different HPA-1a screening scenarios were tested in a decision analysis model and assessed for diagnostic, treatment, intervention and lifetime costs and prevention effects compared to the current situation without screening in the Netherlands. Model parameters were based on available data, literature and expert opinions. One-way sensitivity analysis and probabilistic sensitivity analysis were performed.

RESULTS

Adding screening for anti-HPA-1a antibodies to the current antenatal screening programme of the Netherlands will lead to an additional cost of €4.7 million per year and a gain of 226 quality-adjusted life years (QALYs) per year, indicating an incremental cost-effectiveness ratio (ICER) of €20,782 per QALY gained. One-way sensitivity analysis showed that the uncertainty around the incidence of ICH, lifetime costs of disabled children and the probability of having antibody quantitation >3.0 IU/mL at 20 weeks had the highest effect on the ICER.

CONCLUSION

Antenatal anti-HPA-1a screening might be cost effective. To obtain more knowledge and thereby to improve risk stratification, a pilot screening programme is warranted.

Neonatal/perinatal diagnosis of hemolysis using ETCOc

Hemolysis is a pathological shortening of the red blood cell lifespan. When hemolysis occurs in a neonate, hazardous hyperbilirubinemia and severe anemia could result. Hemolysis can be diagnosed, and its severity quantified, by the non-invasive measurement of carbon monoxide (CO) in exhaled breath. The point-of-care measurement is called "End-tidal CO corrected for ambient CO" (ETCOc). Herein we explain how ETCOc measurements can be used to diagnose and manage various perinatal/neonatal hemolytic disorders. We provide information regarding five clinical situations; 1) facilitating a precise diagnosis among neonates presenting with anemia or jaundice of unknown etiology, 2) monitoring fetal hemolysis with serial measurements of mothers during pregnancy, 3) measuring the duration of hemolysis in neonates with hemolytic disease, 4) measuring neonates who require phototherapy, to determine whether they have hemolytic vs. non-hemolytic jaundice, and 5) measuring all neonates in the birth hospital as part of a jaundice-detection and management program.

Intravenous immunoglobulin for the treatment of severe maternal alloimmunization: individual patient data meta-analysis

OBJECTIVE

This study aimed to investigate the outcomes associated with the administration of maternal intravenous immunoglobulin in high-risk red blood cell-alloimmunized pregnancies.

DATA SOURCES

Medline, Embase, and Cochrane Library were systematically searched until June 2023.

STUDY ELIGIBILITY CRITERIA

This review included studies reporting on pregnancies with severe red blood cell alloimmunization, defined as either a previous fetal or neonatal death or the need for intrauterine transfusion before 24 weeks of gestation in the previous pregnancy as a result of hemolytic disease of the fetus and newborn.

METHODS

Cases were pregnancies that received intravenous immunoglobulin, whereas controls did not. Individual patient data meta-analysis was performed using the Bayesian framework.

RESULTS

Individual patient data analysis included 8 studies consisting of 97 cases and 97 controls. Intravenous immunoglobulin was associated with prolonged delta gestational age at the first intrauterine transfusion (gestational age of current pregnancy - gestational age at previous pregnancy) (mean difference, 3.19 weeks; 95% credible interval, 1.28-5.05), prolonged gestational age at the first intrauterine transfusion (mean difference, 1.32 weeks; 95% credible interval, 0.08-2.50), reduced risk of fetal hydrops at the time of first intrauterine transfusion (incidence rate ratio, 0.19; 95% credible interval, 0.07-0.45), reduced risk of fetal demise (incidence rate ratio, 0.23; 95% credible interval, 0.10-0.47), higher chances of live birth at ≥28 weeks (incidence rate ratio, 1.88; 95% credible interval, 1.31-2.69;), higher chances of live birth at ≥32 weeks (incidence rate ratio, 1.93; 95% credible interval, 1.32-2.83), and higher chances of survival at birth (incidence rate ratio, 1.82; 95% credible interval, 1.30-2.61). There was no substantial difference in the number of intrauterine transfusions, hemoglobin level at birth, bilirubin level at birth, or survival at hospital discharge for live births.

CONCLUSION

Intravenous immunoglobulin treatment in pregnancies at risk of severe early hemolytic disease of the fetus and newborn seems to have a clinically relevant beneficial effect on the course and severity of the disease.

The role of immunoglobulin transport receptor, neonatal Fc receptor in mucosal infection and immunity and therapeutic intervention

The neonatal Fc receptor (FcRn) can transport IgG and antigen-antibody complexes participating in mucosal immune responses that protect the host from most pathogens' invasion via the respiratory, digestive, and urogenital tracts. FcRn expression can be triggered upon stimulation with pathogenic invasion on mucosal surfaces, which may significantly modulate the innate immune response of the host. As an immunoglobulin transport receptor, FcRn is implicated in the pathophysiology of immune-related diseases such as infection and autoimmune disorders. In this review, we thoroughly summarize the recent advancement of FcRn in mucosal immunity and its therapeutic strategy. This includes insights into its regulation mechanisms of FcRn expression influenced by pathogens, its emerging role in mucosal immunity and its potential probability as a therapeutic target in infection and autoimmune diseases.

A novel pyrosequencing strategy for RHD zygosity for predicting risk of hemolytic disease of the fetus and newborn

OBJECTIVE

The aim of this study was the development of an accurate and quantitative pyrosequence (PSQ) method for paternal RHD zygosity detection to help risk management of hemolytic disease of the fetus and newborn (HDFN).

METHODS

Blood samples from 96 individuals were genotyped for RHD zygosity using pyrosequencing assay. To validate the accuracy of pyrosequencing results, all the samples were then detected by the mismatch polymerase chain reaction with sequence-specific primers (PCR-SSP) method and Sanger DNA sequencing. Serological tests were performed to assess RhD phenotypes.

RESULTS

Serological results revealed that 36 cases were RhD-positive and 60 cases were RhD-negative. The concordance rate between pyrosequencing assay and mismatch PCR-SSP assay was 94.8% (91/96). There were 5 discordant results between pyrosequencing and the mismatch PCR-SSP assay. Sanger sequencing confirmed that the pyrosequencing assay correctly assigned zygosity for the 5 samples.

CONCLUSION

This DNA pyrosequencing method accurately detect RHD zygosity and will help risk management of pregnancies that are at risk of HDFN.

Current Insights Into K-associated Fetal Anemia and Potential Treatment Strategies for Sensitized Pregnancies

K-associated anemic disease of the fetus and newborn (K-ADFN) is a rare but life-threatening disease in which maternal alloantibodies cross the placenta and can mediate an immune attack on fetal red blood cells expressing the K antigen. A considerably more common disease, D-associated hemolytic disease of the fetus and newborn (D-HDFN), can be prophylactically treated using polyclonal α-D antibody preparations. Currently, no such prophylactic treatment exists for K-associated fetal anemia, and disease is usually treated with intrauterine blood transfusions. Here we review current understanding of the biology of K-associated fetal anemia, how the maternal immune system is sensitized to fetal red blood cells, and what is understood about potential mechanisms of prophylactic HDFN interventions. Given the apparent challenges associated with preventing alloimmunization, we highlight novel strategies for treating sensitized mothers to prevent fetal anemia that may hold promise not only for K-mediated disease, but also for other pathogenic alloantibody responses.

How do we perform intrauterine transfusions?

BACKGROUND

Intrauterine transfusion (IUT) is an invasive but critical and potentially life-saving intervention for severe fetal anemia with demonstrated improvement in outcomes. The fetus is vulnerable to hemodynamic alterations and transfusion-related adverse events; therefore, special consideration must be given to blood component selection and modification. There is widespread IUT practice variability, and existing guidance primarily relies on expert opinion and single center experiences.

STUDY DESIGN AND METHODS

Experts in Maternal Fetal Medicine, Pediatric Hematology, and Transfusion Medicine from centers across the United States, collectively performing about 120 IUT annually, offer a multidisciplinary perspective on the performance of IUT and preparation of blood components. This perspective includes strategies for identifying an at-risk fetus, communicating between disciplines, determining the necessary blood volume, selecting and processing blood components, documenting the procedure in medical record, and managing the neonate.

RESULTS

Identifying an at-risk fetus relies on review of the clinical history, non-invasive monitoring, and laboratory evaluation. We recommend the use of relatively fresh, group O, cytomegalovirus-safe, freshly irradiated, red blood cells (RBC) that are Hemoglobin S negative and antigen-negative for any maternal antibody, if indicated. These RBC units should be concentrated to remove additives and increase the hematocrit thus minimizing fluctuations in fetal volume status. The units intended for IUT should be labeled clearly and the documentation of transfusion differentiated in the maternal medical record.

DISCUSSION

An awareness of the technical, logistical, and regulatory considerations for IUT performance will facilitate improved communication and patient care, especially when rare units of RBC are required.

FcRN receptor antagonists in the management of myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disorder characterized by autoantibodies specifically directed against proteins located within the postsynaptic membrane of the neuromuscular junction. These pathogenic autoantibodies can be reduced by therapies such as plasma exchange, IVIG infusions and other immunosuppressive agents. However, there are significant side effects associated with most of these therapies. Since there is a better understanding of the molecular structure and the biological properties of the neonatal Fc receptors (FcRn), it possesses an attractive profile in treating myasthenia gravis. FcRn receptors prevent the catabolism of IgG by impeding their lysosomal degradation and facilitating their extracellular release at physiological pH, consequently extending the IgG half-life. Thus, the catabolism of IgG can be enhanced by blocking the FcRn, leading to outcomes similar to those achieved through plasma exchange with no significant safety concerns. The available studies suggest that FcRn holds promise as a versatile therapeutic intervention, capable of delivering beneficial outcomes in patients with distinct characteristics and varying degrees of MG severity. Efgartigimod is already approved for the treatment of generalized MG, rozanolixizumab is under review by health authorities, and phase 3 trials of nipocalimab and batoclimab are underway. Here, we will review the available data on FcRn therapeutic agents in the management of MG.

The choice of new treatments in autoimmune hemolytic anemia: how to pick from the basket?

Autoimmune hemolytic anemia (AIHA) is defined by increased erythrocyte turnover mediated by autoimmune mechanisms. While corticosteroids remain first-line therapy in most cases of warm-antibody AIHA, cold agglutinin disease is treated by targeting the underlying clonal B-cell proliferation or the classical complement activation pathway. Several new established or investigational drugs and treatment regimens have appeared during the last 1-2 decades, resulting in an improvement of therapy options but also raising challenges on how to select the best treatment in individual patients. In severe warm-antibody AIHA, there is evidence for the upfront addition of rituximab to prednisolone in the first line. Novel agents targeting B-cells, extravascular hemolysis, or removing IgG will offer further options in the acute and relapsed/refractory settings. In cold agglutinin disease, the development of complement inhibitors and B-cell targeting agents makes it possible to individualize therapy, based on the disease profile and patient characteristics. For most AIHAs, the optimal treatment remains to be found, and there is still a need for more evidence-based therapies. Therefore, prospective clinical trials should be encouraged.

Clinical Effect of Microneedle Injection Combined with Blood Transfusion in the Treatment of Severe Anemia Complicated with Vitiligo under Regenerative Medical Technology

To explore the clinical efficacy of microneedle injection combined with blood transfusion in the treatment of severe anemia complicated with vitiligo based on regenerative medical technology and provide the theoretical basis for the adoption of microneedle technology, 60 patients with severe anemia complicated with vitiligo were selected as research objects. With 15 patients in each group, they were randomly assigned to the control group (calcipotriol ointment external application), observation group A (external application of moist exposed burn ointment (MEBO), observation group B (external application of MEBO combined with blood transfusion), and observation group C (microneedle injection of MEBO combined with blood transfusion). Blood indexes and plaque recovery of patients in different periods were detected. The total protein (TP) content in group C (62.3 ± 3.3 g/L and 64.3 ± 2.88 g/L) was remarkably higher than that in the control group (51.3 ± 3.17 g/L and 52.4 ± 3.17 g/L) and group A (52.6 ± 2.91 g/L and 51.8 ± 2.98 g/L)) at the 5th and 7th weeks after the treatment (P < 0.05). The albumin (ALB) content in group C (42.9 ± 3.28 g/L and 45.3 ± 3.1 g/L) was signally higher than that in the control group (41.8 ± 3.44 g/L and 41.9 ± 3.23 g/L) and group A (41.3 ± 2.91 g/L and 42.1 ± 3.02 g/L) at the 5th and 7th weeks after the treatment, and the content was markedly higher than that in group B at 5th week (P < 0.05). The wound healing rates of group C at the 3rd, 5th, and 7th weeks after the treatment (38.44%, 56.6%, and 90.23%) were greatly higher than those of the control group, group A, and group B (P < 0.05). Besides, the wound healing rate of group B was higher than that of the control group and group A (40.3% and 75.8%) at the 5th and 7th weeks after the treatment (P < 0.05). To sum up, based on regenerative medical technology, microneedle injection (microneedling is a derma roller process that pricks the skin with minuscule needles. The goal of the treatment is to develop new collagen and skin tissue, resulting in skin that is smoother, firmer, and more toned) combined with blood transfusion had a good therapeutic effect on patients with severe anemia complicated with vitiligo, which could manifestly improve the blood indexes and skin plaques of patients, with a good clinical adoption effect.

Pharmacotherapy of Generalized Myasthenia Gravis with Special Emphasis on Newer Biologicals

Myasthenia gravis (MG) is a chronic, fluctuating, antibody-mediated autoimmune disorder directed against the post-synaptic neuromuscular junctions of skeletal muscles, resulting in a wide spectrum of manifestations ranging from mild to potentially fatal. Given its unique natural course, designing an ideal trial design for MG has been wrought with difficulties and evidence in favour of several of the conventional agents is weak as per current standards. Despite this, acetylcholinesterases and corticosteroids have remained the cornerstones of treatment for several decades with intravenous immunoglobulins (IVIG) and therapeutic plasma exchange (PLEX) offering rapid treatment response, especially in crises. However, the treatment of MG entails long-term immunosuppression and conventional agents are viable options but take longer to act and have a number of class-specific adverse effects. Advances in immunology, translational medicine and drug development have seen the emergence of several newer biological agents which offer selective, target-specific immunotherapy with fewer side effects and rapid onset of action. Eculizumab is one of the newer agents that belong to the class of complement inhibitors and has been approved for the treatment of refractory general MG. Zilucoplan and ravulizumab are other agents in this group in clinical trials. Neisseria meningitis is a concern with all complement inhibitors, mandating vaccination. Neonatal Fc receptor (FcRn) inhibitors prevent immunoglobulin recycling and cause rapid reduction in antibody levels. Efgartigimod is an FcRn inhibitor recently approved for MG treatment, and rozanolixizumab, nipocalimab and batoclimab are other agents in clinical trial development. Although lacking high quality evidence from randomized clinical trials, clinical experience with the use of anti-CD20 rituximab has led to its use in refractory MG. Among novel targets, interleukin 6 (IL6) inhibitors such as satralizumab are promising and currently undergoing evaluation. Cutting-edge therapies include genetically modifying T cells to recognise chimeric antigen receptors (CAR) and chimeric autoantibody receptors (CAAR). These may offer sustained and long-term remissions, but are still in very early stages of evaluation. Hematopoietic stem cell transplantation (HSCT) allows immune resetting and offers sustained remission, but the induction regimens often involve serious systemic toxicity. While MG treatment is moving beyond conventional agents towards target-specific biologicals, lack of knowledge as to the initiation, maintenance, switching, tapering and long-term safety profile necessitates further research. These concerns and the high financial burden of novel agents may hamper widespread clinical use in the near future.

Maternal bleeding complications in pregnancies affected by red blood cell alloimmunization

OBJECTIVE

To investigate whether women with red blood cell (RBC)¹ alloimmunization are more likely to experience bleeding complications during pregnancy or delivery than women without RBC alloimmunization.

STUDY DESIGN

Retrospective study involving all singleton pregnancies affected by RBC alloimmunization and without pre-existing maternal bleeding disorders or placenta previa, from 1 July 1999 to 30 June 2019 ("cases"). Only bleedings not related to invasive procedures (amnio- or cordocenteses) were included. Patients who were already at increased risk of pre- or perinatal bleeding due to their medical history (pre-existing bleeding disorders, antithrombotic therapy), or known obstetrics parameters (placental abnormalities etc.) were not included a priori. Cases were compared to controls without RBC alloimmunization, matched for maternal age and body mass index, from the same tertiary referral center in Austria.

RESULTS

130 cases were compared to 130 controls. Cases had significantly more previous pregnancies and miscarriages and their newborns had lower birthweight and were more often transferred to the intensive care unit than newborns of controls. 18/130 (13.8%) cases, compared to 8/130 (6.2%) controls experienced any bleeding during pregnancy or delivery (p = 0.061). Bleeding most often happened during the third trimester (cases: 4.6% vs. controls 0.8%, p = 0.12) and during or after delivery (cases: 7.7% vs. controls: 4.6%, p = 0.168). Binary logistic regression for the prediction of any bleeding complication during pregnancy, delivery or postpartum revealed immunization against RBC antigens as the only independent contributor (p = 0.04). Age, smoking, or previous obstetric history had no influence on the likelihood of maternal bleeding complications. Neither RBC antibody specificity nor titers were predictive of maternal bleeding during pregnancy or delivery.

CONCLUSION

Pregnancies affected by RBC alloimmunization might be at increased risk of maternal bleeding complications during pregnancy and delivery.

Non-Invasive Fetal K Status Prediction: 7 Years of Experience

Introduction

In the Kell blood group system, the K and k antigens are the clinically most important ones. Maternal anti-K IgG antibodies can lead to the demise of a K-positive fetus in early pregnancy. Intervention can save the fetus. Prenatal K status prediction of the fetus in early pregnancy is desirable and gives a good basis for pregnancy risk management. We present the results from 7 years of clinical experience in predicting fetal K status as well as some theoretical considerations relevant for design of the assay and evaluation of results.

Methods

Blood was collected from 43 women, all immunized against K, at a mean gestational age of 18 weeks (range 10–38). A total of 56 consecutive samples were tested. The KEL *01.01 /KEL *02 single nucleotide variant that determines K status was amplified from maternal plasma DNA by PCR without allele specificity. The PCR product was sequenced by NGS technology, and the number of sequenced KEL *01.01 and KEL *02 reads were counted. Prediction of the fetal K status was based on this count and was compared with the serologically determined K status of the newborns.

Results

All fetal K predictions were in accordance with postnatal serology where available (n = 34), using our current data analysis.

Conclusion

We have developed an NGS-based method for the non-invasive prediction of fetal K status. This approach requires special considerations in terms of primer design, stringent preanalytical sample handling, and careful analytical procedures. We analyzed samples starting at GA 10 weeks and demonstrated the correct prediction of fetal K status. This assay enables timely clinical intervention in pregnancies at risk of hemolytic disease of the fetus and newborn caused by maternal anti-K IgG antibodies.

HDFN Resulting from Anti-U: Alternatives to Allogeneic Intrauterine Transfusion

Hemolytic disease of the fetus and newborn (HDFN) carries significant fetal mortality risks. Although anti-D as a source of HDFN has been prevented for decades using D-specific immunoglobulin to prevent alloimmunization between fetus and mother, minor blood groups may still result in disease, with potentially disastrous consequences if left untreated. Strategies such as intrauterine transfusion, early delivery, and vigilant serologic monitoring of fetal anemia have been the standards of care for alloimmunized patients, but beyond this not much more is possible. Mothers with rare phenotypes who are alloimmunized against extremely common red blood cell antigens may find access to rare antigen-negative blood units limited. This case study presents a healthy G10P6 woman with known anti-U presenting for treatment via intrauterine transfusion in the second trimester and follows the patient through successful delivery. Difficulties in obtaining rare blood for the patient because of concomitant delivery events involving 2 patients with anti-U at the facility opened discussions about the difficulties of and alternatives to intrauterine transfusion where rare blood phenotypes are involved.