"Re-evaluation of variants of uncertain significance in patients with hereditary arrhythmogenic disorders".

BACKGROUND: Genetic diagnostics support the diagnosis of hereditary arrhythmogenic diseases, but variants of uncertain significance (VUS) complicate matters, emphasising the need for regular reassessment. Our study aims to reanalyse rare variants in different genes in order to decrease VUS diagnoses and thus improve risk stratification and personalized treatment for patients with arrhythmogenic disorders. METHODS: Genomic DNA was analysed using Sanger sequencing and next-generation sequencing (NGS). The Data was evaluated using various databases and in silico prediction tools and classified according to current ACMG standards by two independent experts. RESULTS: We identified 53 VUS in 30 genes, of which 17 variants (32%) were reclassified. 13% each were downgraded to likely benign (LB) and benign (B) and 6% were upgraded to likely pathogenic (LP). Reclassifications mainly occurred among variants initially classified in 2017-2019, with rates ranging from 50 to 60%. CONCLUSION: The results support the assumption that regular reclassification of VUS is important, as it provides new insights for genetic diagnostics, that benefit patients and guide therapeutic approach.

German Patient Blood Management Network: effectiveness and safety analysis in 1.2 million patients.

BACKGROUND: Patient Blood Management (PBM) is a patient-centred, systematic, evidence-based approach to improve patient outcomes by managing and preserving a patient's own blood whilst promoting patient safety and empowerment. The effectiveness and safety of PBM over a longer period have not yet been investigated. METHODS: We performed a prospectively designed, multicentre follow-up study with non-inferiority design. Data were retrospectively extracted case-based from electronic hospital information systems. All in-hospital patients (≥18 yr) undergoing surgery and discharged between January 1, 2010 and December 31, 2019 were included in the analysis. The PBM programme focused on three domains: preoperative optimisation of haemoglobin concentrations, blood-sparing techniques, and guideline adherence/standardisation of allogeneic blood product transfusions. The outcomes were utilisation of blood products, composite endpoint of in-hospital mortality and postoperative complications (myocardial infarction/ischaemic stroke/acute renal failure with renal replacement therapy/sepsis/pneumonia), anaemia rate at admission and discharge, and hospital length of stay. RESULTS: A total of 1 201 817 (pre-PBM: n=441 082 vs PBM: n=760 735) patients from 14 (five university/nine non-university) hospitals were analysed. Implementation of PBM resulted in a substantial reduction of red blood cell utilisation. The mean number of red blood cell units transfused per 1000 patients was 547 in the PBM cohort vs 635 in the pre-PBM cohort (relative reduction of 13.9%). The red blood cell transfusion rate was significantly lower (P<0.001) with odds ratio 0.86 (0.85-0.87). The composite endpoint was 5.8% in the PBM vs 5.6% in the pre-PBM cohort. The non-inferiority aim (safety of PBM) was achieved (P<0.001). CONCLUSIONS: Analysis of >1 million surgical patients showed that the non-inferiority condition (safety of Patient Blood Management) was fulfilled, and PBM was superior with respect to red blood cell transfusion. CLINICAL TRIAL REGISTRATION: NCT02147795.

Preoperative anaemia and red blood cell transfusion in patients with aneurysmal subarachnoid and intracerebral haemorrhage - a multicentre subanalysis of the German PBM Network Registry.

PURPOSE: Anaemia is common in patients presenting with aneurysmal subarachnoid (aSAH) and intracerebral haemorrhage (ICH). In surgical patients, anaemia was identified as an idenpendent risk factor for postoperative mortality, prolonged hospital length of stay (LOS) and increased risk of red blood cell (RBC) transfusion. This multicentre cohort observation study describes the incidence and effects of preoperative anaemia in this critical patient collective for a 10-year period. METHODS: This multicentre observational study included adult in-hospital surgical patients diagnosed with aSAH or ICH of 21 German hospitals (discharged from 1 January 2010 to 30 September 2020). Descriptive, univariate and multivariate analyses were performed to investigate the incidence and association of preoperative anaemia with RBC transfusion, in-hospital mortality and postoperative complications in patients with aSAH and ICH. RESULTS: A total of n = 9081 patients were analysed (aSAH n = 5008; ICH n = 4073). Preoperative anaemia was present at 28.3% in aSAH and 40.9% in ICH. RBC transfusion rates were 29.9% in aSAH and 29.3% in ICH. Multivariate analysis revealed that preoperative anaemia is associated with a higher risk for RBC transfusion (OR = 3.25 in aSAH, OR = 4.16 in ICH, p < 0.001), for in-hospital mortality (OR = 1.48 in aSAH, OR = 1.53 in ICH, p < 0.001) and for several postoperative complications. CONCLUSIONS: Preoperative anaemia is associated with increased RBC transfusion rates, in-hospital mortality and postoperative complications in patients with aSAH and ICH. TRIAL REGISTRATION: ClinicalTrials.gov , NCT02147795, https://clinicaltrials.gov/ct2/show/NCT02147795.

Pulmonary embolism in neurocritical care-introduction of a novel grading system for risk stratification: the Frankfurt AMBOS score.

Pulmonary embolism (PE) due to deep vein thrombosis is a complication with severe morbidity and mortality rates. Neurocritical care patients constitute an inhomogeneous cohort with often strict contraindications to conventional embolism treatment. The aim of the present study is to identify risk factors for pulmonary embolism for intensified risk stratification in this demanding cohort. In this retrospective analysis, 387 neurocritical care patients received computed tomography for clinical suspicion of PE (304 neurosurgical and 83 neurological patients). Analysed parameters included age, gender, disease pattern, the presence of deep vein thrombosis, resuscitation, in-hospital mortality, present anticoagulation, coronary artery disease, diabetes mellitus, smoking status, hypertension and ABO blood type. Computed tomography confirmed 165 cases of pulmonary embolism among 387 patients with clinical suspicion of pulmonary embolism (42%). Younger age (p < 0.0001), female gender (p < 0.006), neurooncological disease (p < 0.002), non-O blood type (p < 0.002) and the absence of Marcumar therapy (p < 0.003) were identified as significant risk factors for pulmonary embolism. On the basis of the identified risk factors, the AMBOS score system is introduced. Neurocritical care patients with high AMBOS score are at elevated risk for PE and should therefore be put under intensified monitoring for cardiovascular events in neurocritical care units.

Characterization of an N-terminal Nav1.5 channel variant - a potential risk factor for arrhythmias and sudden death?

BACKGROUND: Alterations in the SCN5A gene encoding the cardiac sodium channel Nav1.5 have been linked to a number of arrhythmia syndromes and diseases including long-QT syndrome (LQTS), Brugada syndrome (BrS) and dilative cardiomyopathy (DCM), which may predispose to fatal arrhythmias and sudden death. We identified the heterozygous variant c.316A > G, p.(Ser106Gly) in a 35-year-old patient with survived cardiac arrest. In the present study, we aimed to investigate the functional impact of the variant to clarify the medical relevance. METHODS: Mutant as well as wild type GFP tagged Nav1.5 channels were expressed in HEK293 cells. We performed functional characterization experiments using patch-clamp technique. RESULTS: Electrophysiological measurements indicated, that the detected missense variant alters Nav1.5 channel functionality leading to a gain-of-function effect. Cells expressing S106G channels show an increase in Nav1.5 current over the entire voltage window. CONCLUSION: The results support the assumption that the detected sequence aberration alters Nav1.5 channel function and may predispose to cardiac arrhythmias and sudden cardiac death.

Prevalence of natural and acquired antibodies to amustaline/glutathione pathogen reduced red blood cells.

BACKGROUND: The INTERCEPT™ Blood System for Red Blood Cells (RBCs) utilizes amustaline (S-303) and glutathione (GSH) to inactivate pathogens and leukocytes in transfused RBCs. Treatment-emergent low titer non-hemolytic antibodies to amustaline/GSH RBC were detected in clinical trials using a prior version of the process. The amustaline/GSH process was re-formulated to decrease S-303 RBC adduct formation. STUDY DESIGN AND METHODS: A standard three-cell antibody screening panel was modified to include reagent red cells (RRC) with high (S-303H) or low (S-303L) S-303 adduct density as assessed by flow cytometry, representative of the original and current amustaline/GSH treatment processes, respectively. General hospital and RBC transfusion-dependent patients never exposed, and clinical trial subjects exposed to amustaline/GSH RBC were screened for antibodies to amustaline/GSH RBC using a standardized agglutination assay. RESULTS: Twelve (0.1%) of 10,721 general hospital and 5 (0.5%) of 998 repeatedly-transfused patients not previously exposed to amustaline/GSH RBCs expressed natural, low titer (2-32) IgM and/or IgG (non-IgG1 or IgG3 isotype) antibodies with acridine (a structural element of amustaline) (n = 14) or non-acridine (n = 3) specificity. 11 of 17 sera reacted with S-303L panel RRCs. In clinical studies 81 thalassemia and 25 cardiac surgery patients were transfused with a total of 1085 amustaline/GSH RBCs and no natural or treatment-emergent S-303 antibodies were detected. CONCLUSION: Standardized RRC screening panels are sensitive for the detection of natural and acquired S-303-specific antibodies. Natural low titer antibodies to amustaline/GSH RBC are present in 0.15% of naïve patients. The clinical relevance of these antibodies appears minimal but is under further investigation.

Programmes for the management of preoperative anaemia: audit in ten European hospitals within the PaBloE (Patient Blood Management in Europe) Working Group.

BACKGROUND AND OBJECTIVES: Preoperative anaemia is an independent risk factor for a higher morbidity and mortality, a longer hospitalization and increased perioperative transfusion rates. Managing preoperative anaemia is the first of three pillars of Patient Blood Management (PBM), a multidisciplinary concept to improve patient safety. While various studies provide medical information on (successful) anaemia treatment pathways, knowledge of organizational details of diagnosis and management of preoperative anaemia across Europe is scarce. MATERIALS AND METHODS: To gain information on various aspects of preoperative anaemia management including organization, financing, diagnostics and treatment, we conducted a survey (74 questions) in ten hospitals from seven European nations within the PaBloE (Patient Blood Management in Europe) working group covering the year 2016. RESULTS: Organization and activity in the field of preoperative anaemia management were heterogeneous in the participating hospitals. Almost all hospitals had pathways for managing preoperative anaemia in place, however, only two nations had national guidelines. In six of the ten participating hospitals, preoperative anaemia management was organized by anaesthetists. Diagnostics and treatment focused on iron deficiency anaemia which, in most hospitals, was corrected with intravenous iron. CONCLUSION: Implementation and approaches of preoperative anaemia management vary across Europe with a primary focus on treating iron deficiency anaemia. Findings of this survey motivated the hospitals involved to critically evaluate their practice and may also help other hospitals interested in PBM to develop action plans for diagnosis and management of preoperative anaemia.

Strategies to develop a prophylaxis for the prevention of HPA-1a immunization and fetal and neonatal alloimmune thrombocytopenia.

Anti-HPA-1a-antibodies are the main cause of fetal and neonatal alloimmune thrombocytopenia (FNAIT) which may result in intracranial hemorrhage (ICH) and death among fetuses and newborns. Advances in understanding the pathogenesis of FNAIT and proof of concept for prophylaxis to prevent immunization suggest that development of hyperimmune anti-HPA-1a IgG aimed at preventing immunization against HPA-1a and FNAIT is feasible. Anti-HPA-1a IgG can be obtained either by isolating immunoglobulin from already-immunized women or by development of monoclonal anti-HPA-1a antibodies. Here we discuss recent advances that may lead to the development of a prenatal and postnatal prophylactic treatment for the prevention of HPA-1a-associated FNAIT and life-threatening FNAIT-induced complications.

Red blood cells treated with the amustaline (S-303) pathogen reduction system: a transfusion study in cardiac surgery.

BACKGROUND: Nucleic acid-targeted pathogen inactivation technology using amustaline (S-303) and glutathione (GSH) was developed to reduce the risk of transfusion-transmitted infectious disease and transfusion-associated graft-versus-host disease with red blood cell (RBC) transfusion. STUDY DESIGN AND METHODS: A randomized, double-blind, controlled study was performed to assess the in vitro characteristics of amustaline-treated RBCs (test) compared with conventional (control) RBCs and to evaluate safety and efficacy of transfusion during and after cardiac surgery. The primary device efficacy endpoint was the postproduction hemoglobin (Hb) content of RBCs. Exploratory clinical outcomes included renal and hepatic failure, the 6-minute walk test (a surrogate for cardiopulmonary function), adverse events (AEs), and the immune response to amustaline-treated RBCs. RESULTS: A total of 774 RBC unis were produced. Mean treatment difference in Hb content was -2.27 g/unit (95% confidence interval, -2.61 to -1.92 g/unit), within the prespecified equivalence margins (±5 g/unit) to declare noninferiority. Amustaline-treated RBCs met European guidelines for Hb content, hematocrit, and hemolysis. Fifty-one (25 test and 26 control) patients received study RBCs. There were no significant differences in RBC usage or other clinical outcomes. Observed AEs were within the spectrum expected for patients of similar age undergoing cardiovascular surgery requiring RBCs transfusion. No patients exhibited an immune response specific to amustaline-treated RBCs. CONCLUSION: Amustaline-treated RBCs demonstrated equivalence to control RBCs for Hb content, have appropriate characteristics for transfusion, and were well tolerated when transfused in support of acute anemia. Renal impairment was characterized as a potential efficacy endpoint for pivotal studies of RBC transfusion in cardiac surgery.

Influence of ABO blood type on the outcome after non-aneurysmal subarachnoid hemorrhage.

BACKGROUND: In patients with non-aneurysmal subarachnoid hemorrhage (NA-SAH), the etiology is unknown and the bleeding source remains unidentified. However, the ABO blood type system has a profound role in patient's hemostasis and thrombosis. To date, the aspect of ABO blood type in incidence, clinical course, and outcome after NA-SAH has not been investigated. METHODS: In this retrospective analysis, 81 patients with non-traumatic and non-aneurysmal subarachnoid hemorrhage treated between 2010 and 2014 at the author's institution were included. WFNS admission status, cerebral vasospasm, delayed infarction, ventriculoperitoneal shunt necessity, the Fisher grade, and the modified Rankin Scale were analyzed for their association with ABO blood type. Four hundred seventy patients with aneurysmal subarachnoid hemorrhage served as a control group. RESULTS: The AB blood type is more frequent in NA-SAH compared to aneurysmal patients and the German population (OR 2.45, p ≤ 0.05). Furthermore, NA-SAH with AB blood type showed a similar sequelae compared to aneurysmal patients in terms of shunt necessity (OR 2.00, p ≥ 0.05), cerebral vasospasm (OR 1.66, p ≥ 0.05), and delayed infarctions (OR 1.07, p ≥ 0.05). CONCLUSION: The clinical course of NA-SAH AB blood type patients shows similar severity as of aneurysmal subarachnoid hemorrhage. Therefore, patients with AB blood type should be under intensified observation.

Antibodies to biotinylated red blood cells in adults and infants: improved detection, partial characterization, and dependence on red blood cell-biotin dose.

BACKGROUND: Biotin-labeled red blood cells (BioRBCs) are used for in vivo kinetic studies. Because BioRBC dosing occasionally induces antibodies, a sensitive and specific anti-BioRBC detection assay is needed. STUDY DESIGN AND METHODS: Aims were to 1) develop a gel card assay to evaluate existing, naturally occurring and BioRBC-induced plasma antibodies, 2) compare gel card and tube agglutination detection results, and 3) test for a relationship of antibody induction and BioRBC dose. Reagent BioRBCs were prepared using sulfo-NHS biotin ranging from densities 18 (BioRBC-18) to 1458 (BioRBC-1458) µg/mL RBCs. RESULTS: Among BioRBC-exposed subjects, gel card and tube agglutination results were concordant in 21 of 22 adults and all 19 infant plasma samples. Gel card antibody detection sensitivity was more than 10-fold greater than tube agglutination. Twelve to 16 weeks after BioRBC exposure, induced anti-antibodies were detected by gel card in three of 26 adults (12%) at reagent densities BioRBC-256 or less, but in none of 41 infants. Importantly, induced anti-BioRBC antibodies were associated with higher BioRBC dose (p = 0.008); no antibodies were detected in 18 subjects who received BioRBC doses less than or equal to BioRBC-18. For noninduced BioRBC antibodies, six of 1125 naïve adults (0.3%) and none of 46 naïve infants demonstrated existing anti-BioRBC antibodies using reagent BioRBC-140 or -162. Existing anti-BioRBCs were all neutralized by biotin compounds, while induced antibodies were not. CONCLUSIONS: The gel card assay is more sensitive than the tube agglutination assay. We recommend reagent BioRBC-256 for identifying anti-BioRBCs. Use of a low total RBC biotin label dose (≤ BioRBC-18) may minimize antibody induction.

Patient Blood Management is Associated With a Substantial Reduction of Red Blood Cell Utilization and Safe for Patient's Outcome: A Prospective, Multicenter Cohort Study With a Noninferiority Design.

OBJECTIVE: To determine whether the implementation of patient blood management (PBM) is effective to decrease the use of red blood cell without impairment of patient's safety. BACKGROUND: The World Health Organization encouraged all member states to implement PBM programs employing multiple combined strategies to increase and preserve autologous erythrocyte volume to minimize red blood cell transfusions. Data regarding safety issues are not sufficiently available. METHODS: In this prospective, multicenter study, surgical inpatients from four German University Hospitals were analyzed before (pre-PBM) and after the implementation of PBM. PBM program included multiple measures (ie, preoperative optimization of hemoglobin levels, blood-sparing techniques, and standardization of transfusion practice). Primary aim was to show noninferiority of the PBM cohort with a margin of 0.5%. Secondary endpoints included red blood cell utilization. RESULTS: A total of 129,719 patients discharged between July 2012 and June 2015 with different inclusion periods for pre-PBM (54,513 patients) and PBM (75,206 patients) were analyzed. The primary endpoint was 6.53% in the pre-PBM versus 6.34% in the PBM cohort. The noninferiority aim was achieved (P < 0.001). Incidence of acute renal failure decreased in the PBM cohort (2.39% vs 1.67%; P < 0.001, regression model). The mean number of red blood cell transfused per patient was reduced from 1.21 ±â€Š0.05 to 1.00 ±â€Š0.05 (relative change by 17%, P < 0.001). CONCLUSIONS: The data presented show that implementation of PBM with a more conscious handling of transfusion practice can be achieved even in large hospitals without impairment of patient's safety. Further studies should elucidate which PBM measures are most clinically and cost effective. TRIAL REGISTRATION: PBM-Study ClinicalTrials.gov, NCT01820949.

Patient blood management implementation strategies and their effect on physicians' risk perception, clinical knowledge and perioperative practice - the frankfurt experience.

INTRODUCTION: A multicomponent, evidence-based and interdisciplinary Patient Blood Management (PBM) program was introduced at the University Hospital Frankfurt in July 2013. The implementation strategy included practical and tactical components aimed to increase knowledge on the risks of preoperative anemia, to standardize hemotherapy, and to facilitate PBM components. METHODS: This article analyzes barriers to PBM implementation and outlines a strategy to introduce and manifest PBM. The effects in Frankfurt were measured in a before and after questionnaire study distributed among groups of physicians immediately before and 1 year after PBM implementation. RESULTS: 142 clinicians completed the questionnaire in July 2013 and 101 clinicians in August 2014. Absolute certainty that the treatment of preoperative anemia favorably influences morbidity and mortality rose from 25 to 37%. Transfusion behavior seems to have been affected: In 2014, 56% of clinicians stated that they clinically reassess the patient and analyze hemoglobin following each single red blood cell unit compared to only 38% stating this in 2013. CONCLUSION: These results show that our implementation strategy was effective in changing physicians' risk perception, attitude, and knowledge on PBM principles. Our experience highlights key success factors for the implementation of a comprehensive PBM program.

Safety and effectiveness of a Patient Blood Management (PBM) program in surgical patients--the study design for a multi-centre prospective epidemiologic non-inferiority trial.

BACKGROUND: Preoperative and hospital-acquired anaemia is common among surgical patients. It is associated with an increased risk of morbidity and mortality and a strong risk factor for allogeneic blood transfusions with their own inherent risks. Patient Blood Management (PBM) concepts aim to increase and preserve autologous erythrocyte volume and to optimise haemotherapy. They thus have great potential to benefit patients. METHODS/DESIGN: This prospective, multi-centre clinical trial tests the hypothesis that PBM programs are safe and effective in the care of adult surgical patients. Primary outcome is a composite endpoint of adverse events and in-hospital mortality. DISCUSSION: This trial will determine whether the implementation of a PBM program is safe and effective in terms of clinical outcome compared to a pre-implementation cohort. This trial is registered at www.clinicaltrials.gov (NCT01820949).

[Patient blood management--The inpatient care]. / Patient Blood Management--Der Patient im Krankenhaus.

The multimodal concept of Patient Blood Management touches many aspects of in-hospital treatment. The goals are to preserve and strengthen the patients' own resources in order to avoid transfusion-associated adverse events. This can be achieved by meticulous minimization of perioperative blood loss and the enhancement and full utilization of individual anaemia tolerance. The transfusion of allogeneic blood products shall be guideline-based only. The proposed package of measures has immense potential to increase patient safety!

[Patient blood management--The preoperative patient]. / Patient Blood Management--Der präoperative Patient.

Preoperative anaemia is an independent risk factor for an increase in perioperative morbidity and mortality. Patient Blood Management (PBM) aims for an early detection of anaemia in elective surgery patients. Reasons for anaemia should be detected and causally treated if possible. A multidisciplinary team of specialists aims for diagnosis and causative treatment of easily treatable and frequent causes of anaemia like iron deficiency, bleeding or (autoimmune) haemolysis using patients' specific history, examination, laboratory and technical methods. Such an outpatient PBM programme is only feasible, if anaesthesiologists, surgeons, haematologists, gastroenterologists, gynecologists, laboratory and transfusion medicine specialists work together in a PBM team using a common PBM plan. Communication within this team as well as with the patients' physicians in their private offices is key for a long lasting success of such a PBM programme.

[Patient blood management--How does it work in practice?--the interdisciplinary cooperation]. / Patient Blood Management--Wie geht das praktisch?--Die interdisziplinäre Zusammenarbeit.

Patient blood management (PBM), as a multidisciplinary, evidence-based treatment concept for reducing anemia and blood losses, should be realized in individual hospitals after local adaptation according to the available facilities.The implementation of a PBM program in clinical institutions will be a challenging but in every case worthwhile task. The local facilities may be insufficient to fulfill the training requirements of a large group of different personnel. Accordingly, sustained support by the hospital's management with provision of the necessary resources for personnel and materials is essential. The formation of the core PBM team, in our case consisting initially of anaesthesiologists, surgeons, internists and transfusion medicine specialists as well as - the particularly important - motivated nursing personnel, is one of the most pressing and primary tasks in the establishment of a PBM project.It is also extremely important to firmly anchor the PBM project permanently within the hospital. Possible steps and details for this purpose are presented and discussed in terms of value and weighting by the authors on the basis of their actual experience in Frankfurt University Hospital.

Two cases of Factor XI deficiency: Use of Thrombin Generation Assays (TGA) to detect a non-bleeding phenotype.

Factor XI deficiency is a rare disorder of hemostasis. Previously also known as "hemophilia C", this defect has been regarded as a risk factor for bleeding. However, it has been known for long that bleeding tendency and severity of bleeding are not related to the residual factor XI activity in symptomatic patients. Moreover, a large proportion of patients with even severe factor XI deficiency are clinically unremarkable and do not show any signs of abnormal bleeding. Here, we present two cases of factor XI deficiency with a non-bleeding phenotype. Adequate diagnostic work-up and evaluation of the bleeding risk are reported and discussed with focus on thrombin generation assays (TGA) for the prediction of bleeding in affected patients. This is of high relevance in affected patients, particularly in the context of surgery.

A Phase 1b PK/PD Study to Demonstrate Antigen Elimination With RLYB212, a Monoclonal Anti-HPA-1a Antibody for FNAIT Prevention.

BACKGROUND: Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a rare bleeding disorder of the fetus/newborn caused by development of maternal alloantibodies against fetal human platelet antigens (HPAs), predominantly HPA-1a. Currently there are no treatments available to prevent maternal alloimmunization to HPAs or FNAIT. METHODS: This proof-of-concept study (EudraCT Number: 2021-005380-49) was designed to assess the ability of subcutaneous (SC) RLYB212, a monoclonal anti-HPA-1a antibody, to eliminate HPA-1a positive platelets in an antigen challenge model of a 30 mL fetal-maternal hemorrhage. Subjects were randomized to receive a single SC dose of RLYB212 or placebo on day 1 in a single-blinded manner, followed by transfusion of 10 × 10^9 HPA-1a positive platelets on day 8. RESULTS: Four subjects received 0.09 mg SC RLYB212, 5 received 0.29 mg SC RLYB212, and 2 received placebo. RLYB212 achieved rapid elimination of HPA-1a positive platelets in a concentration-dependent manner, with concentrations as low as 3.57 ng/mL meeting the prespecified proof-of-concept criterion of ≥90% reduction in platelet elimination half-life vs placebo. Following HPA-1a positive platelet transfusion, a rapid decline was observed in the concentration of RLYB212 over a period of 2 to 24 hours, corresponding to the time needed for RLYB212 to bind to ~10% of HPA-1a on cell surfaces. RLYB212 was well tolerated with no reports of drug-related adverse events. CONCLUSION: The data from this study are consistent with preclinical efficacy data and support the potential use of RLYB212 as a prophylactic treatment for FNAIT that prevents maternal HPA-1a alloimmunization during at-risk pregnancies.