Phase 3 Trial of Concizumab in Hemophilia with Inhibitors.

BACKGROUND: Concizumab is an anti-tissue factor pathway inhibitor monoclonal antibody designed to achieve hemostasis in all hemophilia types, with subcutaneous administration. A previous trial of concizumab (explorer4) established proof of concept in patients with hemophilia A or B with inhibitors. METHODS: We conducted the explorer7 trial to assess the safety and efficacy of concizumab in patients with hemophilia A or B with inhibitors. Patients were randomly assigned in a 1:2 ratio to receive no prophylaxis for at least 24 weeks (group 1) or concizumab prophylaxis for at least 32 weeks (group 2) or were nonrandomly assigned to receive concizumab prophylaxis for at least 24 weeks (groups 3 and 4). After a treatment pause due to nonfatal thromboembolic events in three patients receiving concizumab, including one from the explorer7 trial, concizumab therapy was restarted with a loading dose of 1.0 mg per kilogram of body weight, followed by 0.2 mg per kilogram daily (potentially adjusted on the basis of concizumab plasma concentration as measured at week 4). The primary end-point analysis compared treated spontaneous and traumatic bleeding episodes in group 1 and group 2. Safety, patient-reported outcomes, and pharmacokinetics and pharmacodynamics were also assessed. RESULTS: Of 133 enrolled patients, 19 were randomly assigned to group 1 and 33 to group 2; the remaining 81 were assigned to groups 3 and 4. The estimated mean annualized bleeding rate in group 1 was 11.8 episodes (95% confidence interval [CI], 7.0 to 19.9), as compared with 1.7 episodes (95% CI, 1.0 to 2.9) in group 2 (rate ratio, 0.14 [95% CI, 0.07 to 0.29]; P<0.001). The overall median annualized bleeding rate for patients receiving concizumab (groups 2, 3, and 4) was 0 episodes. No thromboembolic events were reported after concizumab therapy was restarted. The plasma concentrations of concizumab remained stable over time. CONCLUSIONS: Among patients with hemophilia A or B with inhibitors, the annualized bleeding rate was lower with concizumab prophylaxis than with no prophylaxis. (Funded by Novo Nordisk; explorer7 ClinicalTrials.gov number, NCT04083781.).

Acquired haemophilia A in paediatric patients: A retrospective French cohort of eight cases.

Acquired haemophilia A (AHA) is a rare haemorrhagic disease characterised by new-onset haemorrhagic symptoms associated with a dramatic decrease in factor VIII levels and an anti-factor VIII neutralising autoantibody concentration >0.6 Bethesda units. Elderly people are often affected, whereas children are rarely affected; the paediatric incidence reported in the literature is about 0.045 case/million/year. For some time, the paediatric standard of care has been that for adults, but clinicians have often reported poor outcomes. Here, we describe the largest retrospective paediatric AHA cohort assembled to date, including eight patients diagnosed in France from 2000 to 2020.

How I manage pregnancy in women with Glanzmann thrombasthenia.

Glanzmann thrombasthenia (GT) is a rare inherited platelet function disorder caused by a quantitative and/or qualitative defect of the αIIbß3 integrin. Pregnancy and delivery are recognized risk periods for bleeding in women with GT. The newborn may also be affected by fetal and neonatal immune thrombocytopenia induced by the transplacental passage of maternal anti-αIIbß3 antibodies, which can lead to severe hemorrhage and fetal loss. Pregnancy in women with GT thus requires a multidisciplinary approach, including prepregnancy counseling and a treatment plan for delivery for both the mother and child. In this article, we summarize the current knowledge on pregnancy in women with GT and describe how we manage this severe platelet disorder in our clinical practice.

Outcomes and outcome measures.

INTRODUCTION: Advances in haemophilia treatment have resulted in a near-normal life expectancy, lower burden of bleeding and treatment, and improved quality of life in high-income countries. Bleeding rate is approaching zero and novel parameters should be evaluated to assess the efficacy of treatment not only from the clinical point of view by using new methodologies (e.g. joint health assessment), but also from the patient's perspective (e.g. pain, quality of life, treatment satisfaction). METHODS AND RESULTS: This approach should be aimed at combining objective clinical methodologies and patient-reported outcomes (PROs). However, some instruments used for assessing PROs are still suboptimal and not properly validated. Recent evidence suggests that these tools can take advantage from a more personalized designed approach and could be effectively improved and serve to facilitate the patient's self-evaluation. For other congenital bleeding disorders (BDs), a set of patient-relevant outcomes has been also defined that overlap substantially those of haemophilia, including bleeding, side effects and complications, and PROs, such as pain, physical functioning, impact on daily life including school and work and mental health. There is a growing focus on addressing women-specific outcomes in BDs, reflecting an increased awareness of the unique challenges faced by women in this context. However, the development of tailored tools is imperative to further advance the progress in managing women with BDs, ensuring more accurate monitoring and personalized care. CONCLUSIONS: How incorporating these outcome measures in the process of approval of novel treatments for these disorders by regulatory authorities remains to be established.

A focus on dominant negative variants in a series of 170 heterozygous FXI-deficient patients.

INTRODUCTION: Dominant-negative effects have been described for 10 F11 variants in the literature. AIM: The current study aimed at identifying putative dominant-negative F11 variants. MATERIAL AND METHODS: This research consisted in a retrospective analysis of routine laboratory data. RESULTS: In a series of 170 patients with moderate/mild factor XI (FXI) deficiencies, we identified heterozygous carriers of previously reported dominant-negative variants (p.Ser243Phe, p.Cys416Tyr, and p.Gly418Val) with FXI activities inconsistent with a dominant-negative effect. Our findings also do not support a dominant-negative effect of p.Gly418Ala. We also identified a set of patients carrying heterozygous variants, among which five out of 11 are novel, with FXI activities suggesting a dominant-negative effect (p.His53Tyr, p.Cys110Gly, p.Cys140Tyr, p.Glu245Lys, p.Trp246Cys, p.Glu315Lys, p.Ile421Thr, p.Trp425Cys, p.Glu565Lys, p.Thr593Met, and p.Trp617Ter). However, for all but two of these variants, individuals with close to half normal FXI coagulant activity (FXI:C) were identified, indicating an inconstant dominant effect. CONCLUSION: Our data show that for some F11 variants recognized has having dominant-negative effects, such effects actually do not occur in many individuals. The present data suggest that for these patients, the intracellular quality control mechanisms eliminate the variant monomeric polypeptide before homodimer assembly, thereby allowing only the wild-type homodimer to assemble and resulting in half normal activities. In contrast, in patients with markedly decreased activities, some mutant polypeptides might escape this first quality control. In turn, assembly of heterodimeric molecules as well as mutant homodimers would result in activities closer to 1:4 of FXI:C normal range.

Dilemmas on emicizumab in children with haemophilia A: A survey of strategies from PedNet centres.

INTRODUCTION: Haemophilia A care has changed with the introduction of emicizumab. Experience on the youngest children is still scarce and clinical practice varies between haemophilia treatment centres. AIM: We aimed to assess the current clinical practice on emicizumab prophylaxis within PedNet, a collaborative research platform for paediatricians treating children with haemophilia. METHODS: An electronic survey was sent to all PedNet members (n = 32) between October 2022 and February 2023. The survey included questions on the availability of emicizumab, on the practice of initiating prophylaxis in previously untreated or minimally treated patients (PUPs or MTPs) and emicizumab use in patients with or without inhibitors. RESULTS: All but four centres (28/32; 88%) responded. Emicizumab was available in clinical practice in 25/28 centres (89%), and in 3/28 for selected patients only (e.g. with inhibitors). Emicizumab was the preferred choice for prophylaxis in PUPs or MTPs in 20/25 centres; most (85%) started emicizumab prophylaxis before 1 year of age (30% before 6 months of age) and without concomitant FVIII (16/20; 80%). After the loading dose, 13/28 centres administered the recommended dosing, while the others adjusted the interval of injections to give whole vials. In inhibitor patients, the use of emicizumab during ITI was common, with low-dose ITI being the preferred protocol. CONCLUSION: Most centres choose to initiate prophylaxis with emicizumab before 12 months of age and without concomitant FVIII. In inhibitor patients, ITI is mostly given in addition to emicizumab, but there was no common practice on how to proceed after successful ITI.

Determinants of adherence and consequences of the transition from adolescence to adulthood among young people with severe haemophilia (TRANSHEMO): A multicentric French national observational cross-sectional study based on the FranceCoag registry.

INTRODUCTION: It is necessary to gain insights into adherence to healthcare in people with severe haemophilia (PwSH), especially during the transition from paediatric to adult care, which is an important phase in lives of young people with childhood chronic disease. This adherence can be considered as a marker of successful transition. OBJECTIVES: The main objective of the quantitative phase of the TRANSHEMO project was to compare the adherence to healthcare between adolescents and young adults (YAs) with severe haemophilia. The secondary objective was to identify the determinants (facilitators and barriers) of this adherence and associations between these determinants. METHODS: A multicentre, observational, cross-sectional study was conducted in 2017-2019 on PwSH aged between 14 and 17 years (adolescents) or between 20 and 29 years (YAs), included in the FranceCoag registry and having completed the questionnaires. The adherence to healthcare (treatment regimens and clinical follow-up) was compared between adolescents and YAs using the chi-squared test. The determinants of this adherence were analysed by structural equation modelling. RESULTS: There were 277 participants, 107 adolescents, and 170 YAs. The rate of adolescents adhering to healthcare was 82.2%, while the rate of YAs was 61.2% (p < .001). The barriers to the adherence to healthcare were being YA, having repeated at least one school grade and presenting mental health concerns. CONCLUSION: Adolescents had better adherence to healthcare than YAs. According to the determinants enlightened in this project, targeted supportive strategies and adapted therapeutic education programs can be developed for young PwSH to facilitate their adherence to healthcare.

Emicizumab does not interfere with the activated clotting time.

INTRODUCTION: The activated clotting time (ACT) is a useful marker of unfractionated heparin (UFH) activity during cardiopulmonary bypass (CPB) or cardiac catheterization. Emicizumab, recently approved for bleeding prevention in haemophilia A patients, acts like FVIII but does not need prior activation; it therefore shortens coagulation times in assays using intrinsic pathway activators and so is expected to shorten the ACT. AIM: To evaluated emicizumab's impact on heparin-induced ACT (Hemochron®) prolongation. METHODS: We measured the high-range (HR) ACT in citrated blood samples from healthy donors (HDs) (n = 9), CPB patients (n = 3) and emicizumab-treated patients (n = 5) after spiking with UFH and/or emicizumab. The low range (LR) ACT was also measured in spiked-samples from HDs and emicizumab-treated patients. RESULTS: In HDs, the median [interquartile range] baseline HR-ACTs were similar with and without emicizumab (129 [123-138] and 136 [115-141] s for 50 µg/ml, respectively); whatever the concentration of emicizumab (10 to 50 µg/ml), increasing the UFH concentration (1-5 UI/ml) prolonged the HR-ACT. In blood from patients undergoing CPB, the HR-ACT prolongation observed during this procedure was not masked by emicizumab at any concentration. Likewise, the addition of increasing concentrations of UFH to blood from emicizumab-treated patients induced a concentration-dependent prolongation of HR-ACT. Baseline LR-ACT were prolonged in emicizumab-treated patients but as for HR-ACT, emicizumab does not prevent heparin-induced prolongation of LR-ACT. CONCLUSION: Emicizumab does not interfere with UFH-induced ACT prolongation. The hemochron® ACT can be used to monitor UFH in patients receiving emicizumab during CPB or cardiac catheterization.

Occupational integration of adults with severe haemophilia (INTHEMO): A study based on the FranceCoag registry.

INTRODUCTION: Health of people with severe haemophilia (PwSH) improves thanks to the advancements in haemophilia care, giving them more opportunities in occupational integration. However, there is little literature on the occupational integration of PwSH. OBJECTIVES: The main objective of our study was to assess the occupational integration of PwSH and to compare it with that of the general population. The secondary objective was to study the association between individual characteristics (sociodemographic, clinical and psycho-behavioural) and occupational integration of PwSH. METHODS: A multicentre, non-interventional, cross-sectional study was conducted in 2018-2020 on PwSH, aged over 18 and under 65 years and included in the FranceCoag registry. Measurements included indicators of occupational integration, sociodemographic, clinical and psycho-behavioural characteristics. The indicators of occupational integration were compared with those of the general population, using indirect standardization. The data of the general population were available from the National Institute of Statistics and Economic Studies (INSEE). Determinants of occupational integration were explored using structural equation modelling. RESULTS: Of 1262 eligible people, 588 were included. PwSH had a lower employment rate than the general population (standardized ratio, .85; 95% CI, .77-.94). There were more PwSH at tertiary education level than expected (standardized ratio, 1.38; 95% CI, 1.17-1.61). HIV infection, poor physical health and mental health concerns were associated with a higher risk of unemployment in PwSH. CONCLUSION: Employment rate of PwSH is lower than that of the general population despite their higher education level. Target interventions focusing on determinants of difficult occupational integration could be helpful for PwSH.

Effectiveness of long-term prophylaxis using pdFVIII/VWF concentrate in patients with inherited von Willebrand disease.

BACKGROUND: Patients with symptomatic von Willebrand disease (VWD) should be offered long-term prophylaxis (LTP) to prevent recurrent bleedings. Our objective was to evaluate the effectiveness and safety of Voncento®, a plasma-derived FVIII/VWF concentrate (ratio 1:2.4), administrated in LTP. METHODS: We included patients from the OPALE study (May 2016 to April 2021), a French multicenter observational study following patients with inherited VWD, who received a Voncento® LTP during the study period. RESULTS: Among the 130 OPALE-study patients, 23 patients (12 women) received a LTP and were therefore included. The median (range) age was 16 (1-85) years; 16 patients were type 3, 1 was type 2A, 6 were type 2B. Before inclusion, 19 (83%) were under LTP and 4 (17%) received on-demand (OD) treatment. The indications for initiating prophylaxis in the overall population were joint bleeding (43%), ear, nose, and throat (ENT) bleeding including epistaxis or oral bleeding (39%), and recurrent muscle hematoma (22%). The medians (ranges) dose of Voncento® per infusion, frequency, and weekly dose were 45 (33-109) IU/kg, 2 infusions per week, and 96 (44-222) IU/kg/week, respectively. The median (range) annualized bleeding rate (ABR) was 0.8, 0.7 (0-3.5), and 0 (0-2.3) for type 2A, 2B, 3 patients, respectively. There was no difference regarding to the dose, frequency of infusion, or in terms of ABR in 9/19 patients who replaced previous concentrates with Voncento®. During the study period, no adverse event was reported. CONCLUSION: These results suggest that Voncento® is effective to prevent recurrent bleedings in patients symptomatic VWD.

[Young girls and women with congenital bleeding disorders - The challenges of early diagnosis]. / Jeunes filles et femmes avec une maladie hémorragique constitutionnelle - Les enjeux du diagnostic précoce.

Diagnosis of young girls and women with congenital bleeding disorders (CBD) is often delayed. The lack of knowledge of the challenges faced during menstrual cycles and childbirth contribute to this situation. Therefore, a better understanding and identification of the barriers to diagnosis become a useful tool for implementing the steps that promote equitable access and appropriate care. As such, the role of front-line healthcare professionals is crucial in detecting the relevant bleeding symptoms, initiating the first stages of the work-up needed, organizing early access to a specialized clinics and starting non-specific treatments, such as antifibrinolytics for abnormal uterine bleeding, even in the absence of a specific diagnosis of the type of CBD.

Les jeunes filles et femmes avec une maladie hémorragique constitutionnelle (MHC) sont souvent diagnostiquées avec retard. La méconnaissance des défis auxquels elles font face lors des cycles menstruels et des accouchements contribue à cette errance. Mieux comprendre et identifier les freins au diagnostic devient donc un levier utile pour mettre en œuvre les étapes favorisant un accès équitable à un parcours de soins et de suivi adapté. À ce titre, le rôle des acteurs de santé de première ligne est crucial pour dépister les symptômes hémorragiques pertinents, initier les premières étapes du bilan, organiser l'accès précoce à une consultation spécialisée et débuter un traitement non spécifique, tels que les antifibrinolytiques pour les saignements utérins anormaux (SUA), même en absence d'un diagnostic précis du type de MHC.

Women and girls with haemophilia: Lessons learned.

Severe and moderate factor VIII (FVIII) or IX (FIX) deficiencies in female carriers of haemophilia are rarely observed, but mild deficiency is quite frequent, although insufficiently recognized and registered. The confusion between the genetic diagnosis of the carriership, mainly assessed at adult age and the diagnosis of the bleeding disorder for those who have low factor levels often prevents early diagnosis of a potential bleeding risk. The factor levels in obligate or potential carriers of haemophilia can be assessed during childhood, possibly apart from genetic assays. The absence of early recognition of the bleeding disorder precludes the anticipation of menarche and the prevention of potential heavy menstrual bleeding to heavy menstrual bleeding. Standardized bleeding assessment tools (BAT) have demonstrated that women and girls with haemophilia (WGWH) have increased bleeding scores as compared to the general female population, however weakly correlating with factor levels. More recent evidence has highlighted that hemarthroses affect 4% to 19% of carriers and that some of them could experience sub-clinical joint bleeding. Desmopressin for women with FVIII deficiency and abnormal ISTH-BAT scores had a significantly lower FVIII response to DDAVP compared to those with normal bleeding scores, which could at least partially explain more postsurgical bleeding. Management of delivery of haemophilia carriers requires attention to the risks of maternal bleeding, the risks of foetal bleeding, preconception and prenatal care, strategies to reduce maternal bleeding, choice of mode of delivery to reduce foetal/neonatal bleeding, and postpartum care. Either prior to pregnancy, or during early pregnancy, a plan should be developed that addresses the needs of both the mother and her unborn baby. If the unborn baby is a male proven to be or potentially affected by moderate or severe form of haemophilia, there is a risk of severe foetal bleeding, so a planned caesarean delivery may be preferred. If the unborn baby is a carrier, or potentially affected carrier, there is still the risk of non-severe bleeding so invasive foetal procedures and operative vaginal delivery (forceps or vacuum) should be avoided. Further studies based on large cohorts will help the community to favour earlier diagnosis, increase knowledge on WGWH and promote better care.

Managing women-specific bleeding in inherited bleeding disorders: A multidisciplinary approach.

INTRODUCTION: Multidisciplinary management of women-specific bleeding is important to preserve quality of life, healthy reproduction and social participation of women and girls with bleeding disorders (WBD). AIM: To support appropriate multidisciplinary care for WBD in haemophilia treatment centres. METHODS: Two case examples are presented and management issues discussed from different health care perspectives, including the nurse, patient, psychologist, gynaecologist, geneticist, psychosexual therapist and haematologist. RESULTS: Woman with bleeding disorders may experience heavy menstruation from menarche onwards. This has a physical and psychosocial impact requiring a multidisciplinary approach. If a woman with an inherited bleeding disorder desires to become pregnant, preconception counselling is essential, to discuss genetic diagnosis, state of the art treatment options for the bleeding disorder in question and possible choices to prevent having an affected child, as well as maternal bleeding risks during conception, delivery and the post-partum period. CONCLUSION: Adequate management and good education of WBD requires a patient-centred multidisciplinary approach with experienced specialists in a haemophilia treatment centre.

European principles of care for women and girls with inherited bleeding disorders.

INTRODUCTION: Despite increasing awareness of issues faced by women and girls with inherited BDs (WGBD), standards of care are lacking, with disparities in diagnosis and treatment for WGBD across Europe. We aimed to develop practical principles of care (PoC) to promote standardization of care for WGBD within European Haemophilia Treatment and Comprehensive Care Centres (HTC/CCCs). METHODS: The co-creation process, supported by the European Association for Haemophilia and Allied Disorders, consisted of four multidisciplinary meetings with health care providers (HCPs) experienced in WGBD care, and European Haemophilia Consortium representatives, combined with broad patient and HCP consultations in the European haemophilia community. Relevant medical societies outside Europe were contacted for confirmation. RESULTS: We developed ten PoC for WGBD, stressing the importance and benefits of a centralized, multidisciplinary, comprehensive, family-centred approach to support and manage WGBD during all life stages. These PoC emphasise the right to equitable access and quality of care for all people with BDs, irrespective of gender. Multiple medical societies outside Europe also confirmed their support for endorsement. CONCLUSIONS: Ten PoC for WGBD evolved from an iterative process among stakeholders, supported by relevant medical societies worldwide. These PoC can serve as a benchmark for diagnosis and comprehensive multidisciplinary management of WGBD, and improve awareness of their unique challenges. They offer a framework to guide HTC/CCCs in providing equitable care for all WGBD, both in their own services and in other healthcare settings. Implementation of these principles aims to positively impact the health, wellbeing and quality of life for WGBD.

International recommendations on the diagnosis and treatment of acquired hemophilia A.

Acquired hemophilia A (AHA), a rare bleeding disorder caused by neutralizing autoantibodies against coagulation factor VIII (FVIII), occurs in both men and women without a previous history of bleeding. Patients typically present with an isolated prolonged activated partial thromboplastin time due to FVIII deficiency. Neutralizing antibodies (inhibitors) are detected using the Nijmegen-modified Bethesda assay. Approximately 10% of patients do not present with bleeding and, therefore, a prolonged activated partial thromboplastin time should never be ignored prior to invasive procedures. Control of acute bleeding and prevention of injuries that may provoke bleeding are top priorities in patients with AHA. We recommend treatment with bypassing agents, including recombinant activated factor VII, activated prothrombin complex concentrate, or recombinant porcine FVIII in bleeding patients. Autoantibody eradication can be achieved with immunosuppressive therapy, including corticosteroids, cyclophosphamide and rituximab, or combinations thereof. The median time to remission is 5 weeks, with considerable interindividual variation. FVIII activity at presentation, inhibitor titer and autoantibody isotype are prognostic markers for remission and survival. Comparative clinical studies to support treatment recommendations for AHA do not exist; therefore, we provide practical consensus guidance based on recent registry findings and the authors' clinical experience in treating patients with AHA.

Clinical management of woman with bleeding disorders: A survey among European haemophilia treatment centres.

INTRODUCTION: The impact of bleeding for women with bleeding disorders (WBD) is of increasing focus and importance. Despite this, optimal management strategies are unclear and knowledge gaps persist. AIM: To examine practices and define research priorities on diagnosis and management of WBD in Europe. METHODS: An electronic survey on clinical management of WBD was sent to 136 European haemophilia treatment centres (HTCs), including open questions on knowledge gaps and research priorities. RESULTS: Fifty-nine HTCs from 12 Western (WE) and 13 Central/Eastern European (CEE) countries completed the survey. Less than half runs a joint clinic (24 HTCs, 42%). Most centres without a joint clinic have a named obstetrician (81%) and/or gynaecologist (75%) available for collaboration. Overall 18/54 (33%) European HTCs do not offer preimplantation genetic diagnosis. Third trimester amniocentesis to guide obstetric management is available 28/54 HTCs (52%), less frequent in CEE compared to WE countries (5/17 vs 23/37, P = .03). 53% of HTCs (28/53) reported that only 0%-25% of WBD seek medical advice for heavy menstrual bleeding (HMB). An algorithm managing acute HMB in WBD is lacking in 22/53 (42%) HTCs. The main reported knowledge and research gaps are lack of awareness & education on WBD among patients and caregivers, optimal diagnostic strategies and effective multidisciplinary management of pregnancy & HMB. CONCLUSION: Joint clinics, prenatal diagnostics and algorithms for managing acute HMB are lacking in many European HTCs. HMB may be an underestimated issue. This survey highlights the need to prioritize improvement of knowledge and patient care for WBD across Europe.

Clinical evaluation of bleeds and response to haemostatic treatment in patients with acquired haemophilia: A global expert consensus statement.

BACKGROUND: Acquired haemophilia (AH) is a rare bleeding disorder with significant morbidity and mortality. Most patients initially present to physicians without experience of the disease, delaying diagnosis and potentially worsening outcomes. Existing guidance in AH is limited to clinical opinion of few experts and does not address monitoring bleeds in specific anatomical locations. AIM: Derive consensus from a large sample of experts around the world in monitoring bleeding patients with AH. METHODS: Using the Delphi methodology, a structured survey, designed to derive consensus on how to monitor bleeding patients with AH, was developed by a steering committee for completion by a group of haematologists with an interest in AH. Consensus was defined as ≥75% agreement with a given survey statement. After three rounds of survey refinement, a final list of consensus statements was compiled. RESULTS: Thirty-six global specialists in AH participated. The participants spanned 20 countries and had treated a median of 12.0 (range, 1-50) patients with AH within the preceding 5 years. Consensus was achieved in all items after three survey rounds. In addition to statements on general management of bleeding patients, consensus statements in the following areas were presented: urinary tract, gastrointestinal tract, muscles, skin, joints, nose, pharynx, mouth, intracranial and postpartum. CONCLUSIONS: Here, we present consensus statements derived from a broad sample of global specialists to address monitoring of location-specific bleeds and evaluating efficacy of bleeding treatment in patients with AH. These statements could be applied in practice by treating physicians and validated by individual population surveys.

Anti-αIIb ß3 immunization in Glanzmann thrombasthenia: review of literature and treatment recommendations.

Glanzmann thrombasthenia (GT) is caused by inherited defects of the αIIb ß3 platelet glycoprotein. This bleeding disorder can be treated with platelet transfusion therapy, but some patients will be immunized and begin to form anti-human leucocyte antigen (HLA) and/or anti-αIIb ß3 antibodies. These antibodies can bind and interfere with the function of the transfused platelets, rendering treatment ineffective. However, platelet transfusion refractoriness attributable to HLA antibodies may be managed by the selection of compatible donors, although they are not always readily available, particularly in an emergency. Thus, anti-αIIb ß3 antibodies represent one of the most severe complications in GT. Both genetic and environmental factors may contribute to the risk of anti-αIIb ß3 development, but the underlying pathogenic mechanisms are still unknown. This review will summarize the current knowledge of the risk factors for development of anti-αIIb ß3 antibodies in patients with GT and discuss how these findings may influence the clinical management of patients.

Alloimmunization in Congenital Deficiencies of Platelet Surface Glycoproteins: Focus on Glanzmann's Thrombasthenia and Bernard-Soulier's Syndrome.

Glanzmann's thrombasthenia (GT) and Bernard-Soulier's syndrome (BSS) are well-understood congenital bleeding disorders, showing defect/deficiency of platelet glycoprotein (GP) IIb/IIIa (integrin αIIbß3) and GPIb-IX-V complexes respectively, with relevant clinical, laboratory, biochemical, and genetic features. Following platelet transfusion, affected patients may develop antiplatelet antibodies (to human leukocyte antigen [HLA], and/or αIIbß3 in GT or GPIb-IX in BSS), which may render future platelet transfusion ineffective. Anti-αIIbß3 and anti-GPIb-IX may also cross the placenta during pregnancy to cause thrombocytopenia and bleeding in the fetus/neonate. This review will focus particularly on the better studied GT to illustrate the natural history and complications of platelet alloimmunization. BSS will be more briefly discussed. Platelet transfusion, if unavoidable, should be given judiciously with good indications. Patients following platelet transfusion, and women during and after pregnancy, should be monitored for the development of platelet antibodies. There is now a collection of data suggesting the safety and effectiveness of recombinant activated factor VII in the management of affected patients with platelet antibodies.