The definition, diagnosis and management of mild hemophilia A: communication from the SSC of the ISTH

Nonsevere Hemophilia: The Need for a Renewed Focus and Improved Outcomes

People with nonsevere hemophilia (PWNSH) are phenotypically more diverse than those with severe hemophilia. Perceptions relating to a "nonsevere" phenotype have contributed to fewer research initiatives, fewer guidelines on optimal management, and a lack of standards for surveillance and clinical assessment for affected individuals. In many cases, episodes of abnormal bleeding could, if investigated, have led to earlier diagnosis. Furthermore, the major recent developments in therapy for hemophilia have largely focused on severe disease and, as a group, PWNSH have not been included in many key clinical trials. Benefiting people with severe disease, innovative replacement therapies have generally targeted factor levels that are above those present in a large proportion of PWNSH. Therapeutic advances can lead to improvement in phenotype for people with severe hemophilia over that currently experienced by many PWNSH. As a result, we are approaching a point where PWNSH may, in many countries, have a higher risk of bleeding and restriction in lifestyle than those with severe disease but with more limited therapeutic options. Given the multiple major advances in treatment for people with hemophilia, it is timely to review the aspects of nonsevere disease, to ensure equity in care and management for all individuals with this condition.

A bispecific antibody NXT007 exerts a hemostatic activity in hemophilia A monkeys enough to keep a nonhemophilic state

BACKGROUND

Emicizumab, a factor (F) VIIIa-function mimetic bispecific antibody (BsAb) to FIXa and FX, has become an indispensable treatment option for people with hemophilia A (PwHA). However, a small proportion of PwHA still experience bleeds even under emicizumab prophylaxis, as observed in the long-term outcomes of clinical studies. A more potent BsAb may be desirable for such patients.

OBJECTIVES

To identify a potent BsAb to FIXa and FX, NXT007, surpassing emicizumab by in vitro and in vivo evaluation.

METHODS

New pairs of light chains for emicizumab's heavy chains were screened from phage libraries, and subsequent antibody optimization was performed. For in vitro evaluation, thrombin generation assays were performed with hemophilia A plasma. In vivo hemostatic activity was evaluated in a nonhuman primate model of acquired hemophilia A.

RESULTS

NXT007 exhibited an in vitro thrombin generation activity comparable to the international standard activity of FVIII (100 IU/dL), much higher than emicizumab, when triggered by tissue factor. NXT007 also demonstrated a potent in vivo hemostatic activity at approximately 30-fold lower plasma concentrations than emicizumab's historical data. In terms of dose shift between NXT007 and emicizumab, the in vitro and in vivo results were concordant. Regarding pharmacokinetics, NXT007 showed lower in vivo clearance than those shown by typical monoclonal antibodies, suggesting that the Fc engineering to enhance FcRn binding worked well.

CONCLUSION

NXT007, a potent BsAb, was successfully created. Nonclinical results suggest that NXT007 would have a potential to keep a nonhemophilic range of coagulation potential in PwHA or to realize more convenient dosing regimens than emicizumab.

Neurological Complications Associated with Hereditary Bleeding Disorders

PURPOSE OF REVIEW

Hereditary bleeding disorders may have a wide variety of clinical presentations ranging from mild mucosal and joint bleeding to severe central nervous system (CNS) bleeding, of which intracranial hemorrhage (ICH) is the most dreaded complication. In this review, we will discuss the pathophysiology of specific hereditary bleeding disorders, namely, hemophilia A, hemophilia B, and von Willebrand disease (vWD); their clinical manifestations with a particular emphasis on neurological complications; a brief overview of management strategies pertaining to neurological complications; and a review of literature guiding treatment strategies.

RECENT FINDINGS

ICH is the most significant cause of morbidity and mortality in patients with hemophilia. Adequate control of bleeding with the administration of specific factors or blood products, identification of risk factors for bleeding, and maintaining optimal coagulant activity are essential for appropriately managing CNS bleeding complications in these patients. The administration of specific recombinant factors is tailored to a patient's pharmacokinetics and steady-state levels. During acute bleeding episodes, initial factor activity should be maintained between 80 and 100%. Availability of monoclonal antibody Emicizumab has revolutionized prophylactic therapies in patients with hemophilia. Management of ICH in patients with vWD involves using plasma-derived factor concentrates, recombinant von Willebrand factor, and supportive antifibrinolytic agents individualized to the type and severity of vWD. Hemophilia and vWD are the most common hereditary bleeding disorders that can predispose patients to life-threatening CNS complications-intracranial bleeds, intraspinal bleeding, and peripheral nerve syndromes. Early care coordination with a hematologist can help develop an effective prophylactic regimen to avoid life-threatening bleeding complications in these patients. Further research is needed to evaluate using emicizumab as an on-demand treatment option for acute bleeding episodes in patients with hemophilia.

Treatment of congenital coagulopathies, from biologic to biotechnological drugs: The relevance of gene editing (CRISPR/Cas)

Congenital coagulopathies have, throughout the history of medicine, been a focus of scientific study and of great interest as they constitute an alteration of one of the most important and conserved pathways of evolution. The first therapeutic strategies developed to address them were aimed at restoring the blood components lost during hemorrhage by administering whole blood or plasma. Later on, the use of cryoprecipitates was a significant breakthrough as it made it possible to decrease the volumes of blood infused. In the 1970' and 80', clotting factor concentrates became the treatment and, from the 1990's to the present day, recombinant factors -with increasingly longer half-lives- have taken over as the treatment of choice for certain coagulopathies in a seamless yet momentous transition from biological to biotechnological drugs. The beginning of this century, however, saw the emergence of new advanced (gene and cell) treatments, which are currently transforming the therapeutic landscape. The possibility to use cells and viruses as well as specific or bispecific antibodies as medicines is likely to spark a revolution in the world of pharmacology where therapies will be individualized and have long-term effects. Specifically, attention is nowadays focused on the development of gene editing strategies, chiefly those based on CRISPR/Cas technology. Rare coagulopathies such as hemophilia A and B, or even ultra-rare ones such as factor V deficiency, could be among those deriving the greatest benefit from these new developments.

A portable point-of-care testing device for forward blood typing with hemophilia diagnosis

This paper presents a portable point-of-care testing (POCT) device to conduct simultaneous and on-site tests of ABO and Rh(D) forward blood typing and hemophilia diagnosis using only a small amount of human whole blood sample. The POCT device consisted of a spinning module, a measuring circuit, an interdigitated electrode (IDE) for hemophilia diagnosis, and three disposable microfluidic chips for bioassays with anti-A, anti-B, and anti-D, respectively, and measurement of the concentration of factor VIII. Agglutination will occur if red blood cells (RBCs) are exposed to the corresponding antibody. To evaluate the degree of RBC agglutination, a linear sweep voltage, ranging from - 0.5 to + 0.5 V, was applied to the electrodes of the microfluidic chip and the resulting current was measured. For different levels of agglutination, the measured I-V curves were explicitly discriminated, providing five clinical levels from non-agglutination (level 0) to strong agglutination (level 4). The quantitative norm obtained from cubic fitting function of each I-V curve served as the criterion to represent this agglutination level. The ABO blood type was determined by both agglutination levels of the blood sample reacting with anti-A and anti-B. The degree of agglutination with anti-D gave the Rh(D) type. Moreover, the concentration of factor VIII was detected for the determination of hemophilia. Without requiring expensive equipment, this POCT device is especially suitable for usage in emergency or natural disasters to provide quantitative testing in rescue and relief operations.

Development of a haemophilia A gene therapy shared decision-making tool for clinicians

INTRODUCTION

As gene therapies are incorporated into clinical practice, shared decision-making (SDM) is recommended for implementation.

AIM

To inform development of a clinician SDM tool for haemophilia A gene therapy.

METHODS

Clinicians at US Hemophilia Treatment Centers completed semi-structured interviews about their experience with SDM and provided feedback on a clinician SDM tool prototype. Interviews were transcribed verbatim for coding and thematic content analysis.

RESULTS

Ten participants enrolled, eight physicians and two haemophilia nurses. All participants care for adults with haemophilia (1-27 years of experience) and 7 have gene therapy trials open at their institution. Confidence in having a clinical discussion about gene therapy included none (N = 1), slight (N = 3), moderate (N = 5) and high (N = 1). All participants reported familiarity with SDM and agreed that the tool would be useful for their clinical practice. Key themes in participant feedback for the tool were (1) language and presentation; (2) content; and (3) implementation. Participants highlighted the importance of providing unbiased information and having companion tools with patient-centric language.

CONCLUSION

These data highlight the need for SDM tools for haemophilia A gene therapy. Key information to include in the tool are safety, efficacy, cost and detailed information on the gene therapy process. Data should be provided in an unbiased format and allow comparison to other treatments. The tool will be evaluated in clinical practice and refined as clinical trial data and real-world experience mature.

Methodological quality and recommendations of hemophilia clinical practice guidelines: A scoping review

Background and Aims

Hemophilia clinical practice guidelines (CPGs) play a vital role in guiding healthcare professionals' decisions. However, the quality and recommendations of CPGs for hemophilia may vary. This study aimed to assess the methodological quality of hemophilia CPGs published between 2017 and 2021 and compare their recommendations for prophylaxis using clotting factor concentrate.

Methods

We conducted a comprehensive search for relevant CPGs in PubMed, TripDatabase, Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) International Guidelines Database, Google Scholar, and Google. We used the AGREE-II instrument to assess the methodological quality of each CPG and compared their recommendations for prophylaxis.

Results

Of the 11 CPGs that met the inclusion criteria, 5/11 were developed in upper-middle-income countries, and 6/11 used the GRADE methodology. The primary prophylaxis dose recommendations varied among the CPGs, with 4/11 recommending a low dose, 6/11 recommending an intermediate or high dose, and 1/11 not issuing a recommendation. However, only 2/11 CPGs provided justification for their recommendations on initiation and dose, and no economic evaluations were conducted to support these recommendations.

Conclusion

The quality of hemophilia CPGs is not optimal, with inconsistent recommendations for prophylaxis and a lack of justification for these recommendations. To ensure evidence-based and trustworthy recommendations, there is a need for transparency and improvement in the decision-making process of hemophilia CPGs.

Chromogenic Factor VIII Assay for Patients with Hemophilia A and on Emicizumab Therapy

This chapter will describe a method for measuring endogenous and infused Factor VIII (FVIII) in patients on emicizumab therapy (Hemlibra, Genetec, Inc). Emicizumab is a bispecific monoclonal antibody used in patients with hemophilia A, with or without inhibitors. The mechanism of action for emicizumab is novel and mimics the role that FVIII plays in vivo by binding and bridging FIXa and FX. It is vital that the laboratory understands the effect this drug has on coagulation tests and uses a suitable chromogenic assay which is not affected by emicizumab, for determination of FVIII coagulant activity and inhibitors.

A Review of Factor VIII and Factor IX Assay Methods for Monitoring Extended Half-Life Products in Hemophilia A and B

Clinical trials have used a variety of coagulation factor assay methods to assess treatment with recombinant Factor VIII (rFVIII) and recombinant Factor IX (rFIX) extended half-life (EHL) products. However, diagnostic laboratories may use different reagent combinations for routine use or for field trials of EHL products. The focus of this review is on the choice of one-stage clotting and chromogenic Factor VIII and Factor IX methods and the influence that assay principle and components may have on results, including the effects of different activated partial thromboplastin time reagents and factor-deficient plasma. Our aim is to tabulate the findings for each method and reagent group to give laboratories practical guidance as to how the reagent combinations used in their local laboratory compare to others, for the various EHLs available.

Development of an AAV DNA-based synthetic vector for the potential gene therapy of hemophilia in children

Recombinant AAV serotype vectors and their variants have been or are currently being used for gene therapy for hemophilia in several phase I/II/III clinical trials in humans. However, none of these trials have included children with hemophilia since the traditional liver-directed AAV gene therapy will not work in these patients because of the following reasons: (i) Up until age 10–12, the liver is still growing and dividing, and with every cell division, the AAV vector genomes will be diluted out due to their episomal nature; and (ii) Repeated gene delivery will be needed, but repeat dosing, even with an ideal AAV vector is not an option because of pre-existing antibodies to AAV vectors following the first administration. Here we describe the development of an optimized human Factor IX (hF.IX) gene expression cassette under the control of a human liver-specific transthyretin promoter covalently flanked by AAV inverted terminal repeats (ITRs) with no open ends (optNE-TTR-hF.IX), which mediated ~sixfold higher hF.IX levels than that from a linear TTR-hF.IX DNA construct in human hepatoma cells up to four-weeks post-transfection. In future studies, encapsidation of the optNE-TTR-hF.IX DNA in liver-targeted synthetic liposomes, may provide a viable approach for the potential gene therapy for hemophilia in children.

Clinical, cytogenetic, and genomic analyses of an Ecuadorian subject with Klinefelter syndrome, recessive hemophilia A, and 1;19 chromosomal translocation: a case report

Background

Hemophilia A is considered one of the most common severe hereditary disorders. It is an X-linked recessive disease caused by a deficiency or lack of function of the blood clotting factor VIII. Klinefelter syndrome is a genetic disorder that affects male individuals due to one or more extra X chromosomes, present in all cells or with mosaicism. The aneuploidy is due to either mitotic or meiotic chromosome non-disjunction. Chromosomal translocations are a group of genome abnormalities in which a region or regions of a chromosome break and are transferred to a nonhomologous chromosome or a new location in the same chromosome.

Case presentation

Our subject was born in Ecuador at 36 weeks of gestation by vaginal delivery. At 3 months old, the Factor VIII activity measure showed a 23.7% activity indicating a diagnosis of mild hemophilia A. At 1 year old, the karyotype showed an extra X chromosome, consistent with a diagnosis of Klinefelter syndrome, and a translocation between the long arms of chromosomes 1 and 19, at positions q25 and q13, respectively.

Conclusions

Klinefelter syndrome and hemophilia are a rare combination. In the present case report, the subject presents both, meaning that he has inherited one X chromosome from the father and one X chromosome from the mother. Since the father has severe hemophilia A; and the subject presents a below 40% Factor VIII activity, a skewed X inactivation is suggested. Additionally, the proband presents a translocation with the karyotype 47,XXY,t(1;19)(q25;q13). No similar report with phenotypic consequences of the translocation was found. The present report highlights the importance of a correct diagnosis, based not only on the clinical manifestations of a disease but also on its genetic aspects, identifying the value of integrated diagnostics. The subject presents three different genetic alterations, Klinefelter syndrome, hemophilia A, and a 1;19 chromosomal translocation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13039-022-00618-w.

Desmopressin for bleeding in non‐severe hemophilia A: Suboptimal use in a real‐world setting

Background

Desmopressin is an important treatment option in nonsevere hemophilia A because it has several benefits compared with factor (F) concentrates, including no inhibitor risk and much lower costs. Despite these advantages, data are limited on the real‐world use of desmopressin in the treatment of bleeds.

Objective

To describe the clinical use of desmopressin in relation to other therapeutic modalities in the treatment of bleeding episodes in patients with nonsevere hemophilia A.

Methods

Patients with nonsevere hemophilia A aged 12–55 years were included from the DYNAMO cohort study. Data on the desmopressin test response and treated bleeding events in the period January 2009 to July 2020 were retrospectively collected from medical files. An adequate desmopressin test response was defined based on a peak FVIII level of ≥30 IU/dl.

Results

A total of 248 patients with a median age of 38 years (interquartile range 25–49) were included. An adequate desmopressin test response was documented in 25% and 73% of patients with moderate and mild hemophilia, respectively. In adequate responders, 51% of bleeds were exclusively treated with FVIII concentrates, 24% exclusively with desmopressin, 21% with a combination of both and 4% with other treatments. In 54% of bleeds treated with a single dose of factor concentrates, the expected FVIII level after desmopressin exceeded the level targeted.

Conclusion

Most bleeds in patients with an adequate response to desmopressin are treated with factor concentrates. These findings may indicate a suboptimal use of desmopressin and that barriers to the use of desmopressin should be explored.

The important impact of dental care on haemostatic treatment burden in patients with mild haemophilia

BACKGROUND

Mild haemophilia (MH) is mainly characterized by haemorrhages secondary to surgery/invasive procedures or trauma. Haemostatic treatment in MH ranges from on demand to short prophylaxis according to the type of bleeding events and the basal clotting factor level. Oral surgery and dental extractions can represent a frequent haemostatic challenge in MH requiring appropriate treatment. However, only few studies on limited numbers of patients are available in the literature regarding the implications of dental management in patients with MH.

OBJECTIVES

The purpose of the study was to evaluate the impact of dental care on the burden of haemostatic treatment in patients affected by MH.

METHODS

We conducted a retrospective multicentre study evaluating adult patients with MH regularly examined at the Haemophilia Treatment Centres (HTCs) of the Saint-Luc University Hospital, Brussels (Belgium) and of Paolo Giaccone Hospital, Palermo (Italy). The population consisted of 107 male patients with MH, with a mean age of 39 years (range 18-81 years).

RESULTS

The majority of patients (86/107, 79%) needed at least one treatment within the study period, and 44% (38/86) of them received haemostatic therapy for dental care. Haemostatic therapy in our study varied from antifibrinolytic therapy alone and perioperative factor replacement to the absence of treatment at all. The great majority of oral interventions (27/42, 64%) were managed with clotting factor concentrate.

CONCLUSION

This study demonstrates that dental care currently represents a major reason for haemostatic treatments in patients with MH. Maintaining good oral health appears as a priority to minimize avoidable replacement therapy and optimize resources.

Associated comorbidities, healthcare utilization & mortality in hospitalized patients with haemophilia in the United States: Contemporary nationally representative estimates

INTRODUCTION

Current in-hospital burden and healthcare utilization patterns for persons with haemophilia (PWH) A and B, including both children (ages < 18 years) and adults (ages ≥ 18 years), in the United States (US) are lacking.

AIM

To evaluate healthcare utilization, the prevalence of comorbidities, and mortality in hospitalized paediatric and adult PWH using a contemporary nationally representative cohort.

METHODS

Hospitalizations of PWH either as the primary reason for admission (principal diagnosis) or one of all listed diagnoses were identified using ICD-10 codes from the 2017 Nationwide Inpatient Sample (NIS), the largest publicly available all-payer inpatient discharge database in the US. Sampling weights were applied to generate nationally representative estimates.

RESULTS

The contemporary cohort included 10,555 hospitalizations (paediatrics, 18.3%; adults, 81.7%) among PWH as one-of-all listed diagnoses (n = 1465 as principal diagnosis). Median age (interquartile range) was 46 (24-66) years overall; adults, 54 (35-70) years and paediatric, 4 (1-11). The most common comorbidities in adults were hypertension (33.4%), hyperlipidaemia (23.6%), and diabetes (21.1%). In children, hemarthrosis (11.4%), contusions (9.6%), and central line infections (9.3%) were the most common. The overall mortality rate was 2.3%. Median hospital charges per haemophilia admission were $52,616 ($24,303-$135,814) compared to $26,841 ($12,969-$54,568) for all-cause admissions in NIS.

CONCLUSION

Bleeding and catheter-related infections are the significant reasons for paediatric haemophilia admissions. Adult haemophilia admissions tend to be associated with age-related comorbidities. Costs for haemophilia-related hospitalizations are higher than the national average for all-cause hospitalizations.

Short-term biological variation study of plasma hemophilia and thrombophilia parameters in a population of apparently healthy Caucasian adults

OBJECTIVES

Biological variation (BV) data obtained in a standardized way is valuable to assess the analytical requirements and the utility of a reference interval. Our study aimed to determine the short-term BV of thrombophilia (protein S, protein C, activated protein C resistance (APCR) and factor VIII) and hemophilia (factors VIII, IX and XI) parameters in plasma. Coagulation factors V and XII were also evaluated. Based on the obtained data, we assessed analytical performance specifications for the parameters. Finally, we intended to provide a robust tool for comparison of serial measurements of factors V, VIII, IX and XI.

METHODS

A blood draw was performed weekly in 19 apparently healthy Caucasian adults for five weeks at Saint-Luc University Hospital (Brussels, Belgium). Parameters were measured in duplicate. BV components were calculated with a nested analysis of variance after exclusion of outliers.

RESULTS

The analytical coefficient of variation (CV) varied from 1.5 to 4.6%, the within-subject CV from 1.6 to 8.9% and the between-subject CV from 3.8 to 24.1%. All parameters showed high individuality. For most parameters, the analytical goal was met with our assays. Reference change values (RCV) of -16.7% to +20.0%, -20.7% to +26.0%, -15.3% to +18.1% and -13.1% to +15.1% were obtained for factors V, VIII, IX and XI respectively.

CONCLUSIONS

All studied parameters were highly individualized. The assessment of BV data can guide setting analytical goal specifications. Comparison of serial measurements in the follow-up of patients suffering from hepatic failure or mild hemophilia is facilitated by evaluation of the RCV.

IDELVION: A Comprehensive Review of Clinical Trial and Real-World Data

Hemophilia B is a bleeding disorder caused by a deficiency of coagulation factor IX (FIX). Treatment with FIX replacement products can increase FIX activity levels to minimize or prevent bleeding events. However, frequent dosing with standard-acting FIX products can create a high treatment burden. Long-acting products have been developed to maintain bleed protection with extended dosing intervals. Recombinant factor IX–albumin fusion protein (rIX-FP) is a long-acting product indicated for the treatment and prophylaxis of bleeding events and perioperative management in adult and pediatric patients. This review outlines data from all previously treated patients in the Prophylaxis and On-Demand Treatment using Longer Half-Life rIX-FP (PROLONG-9FP) clinical trial program and summarizes real-world data evaluating the use of rIX-FP in routine clinical practice. In the PROLONG-9FP program, rIX-FP demonstrated effective hemostasis in all patients at dose regimens of up to 21 days in patients aged ≥ 18 years and up to 14 days in patients aged < 12 years. rIX-FP has a favorable pharmacokinetic profile and an excellent safety and tolerability profile. Extended dosing intervals with rIX-FP led to high levels of adherence and reduced consumption compared with other FIX therapies. Data from real-world practice are encouraging and reflect the results of the clinical trials.

Long-term correction of hemorrhagic diathesis in hemophilia A mice by an AAV-delivered hybrid FVIII composed of the human heavy chain and the rat light chain

Conventional therapies for hemophilia A (HA) are prophylactic or on-demand intravenous FVIII infusions. However, they are expensive and inconvenient to perform. Thus, better strategies for HA treatment must be developed. In this study, a recombinant FVIII cDNA encoding a human/rat hybrid FVIII with an enhanced procoagulant potential for adeno-associated virus (AAV)-delivered gene therapy was developed. Plasmids containing human FVIII heavy chain (hHC), human light chain (hLC), and rat light chain (rLC) were transfected into cells and hydrodynamically injected into HA mice. Purified AAV viruses were intravenously injected into HA mice at two doses. Results showed that the hHC + rLC protein had a higher activity than the hHC + hLC protein at comparable expression levels. The specific activity of hHC + rLC was about 4- to 8-fold higher than that of their counterparts. Hydrodynamic injection experiments obtained consistent results. Notably, the HA mice undergoing the AAV-delivered hHC + rLC treatment exhibited a visibly higher activity than those treated with hHC + hLC, and the therapeutic effects lasted for up to 40 weeks. In conclusion, the application of the hybrid FVIII (hHC + rLC) via an AAV-delivered gene therapy substantially improved the hemorrhagic diathesis of the HA mice. These data might be of help to the development of optimized FVIII expression cassette for HA gene therapy.

Current therapeutic approaches in the management of hemophilia-a consensus view by the Romanian Society of Hematology

Hemophilia A (HA) and hemophilia B (HB) are rare disorders, being caused by the total lack or under-expression of two factors from the coagulation cascade coded by genes of the X chromosome. Thus, in hemophilic patients, the blood does not clot properly. This results in spontaneous bleeding episodes after an injury or surgical intervention. A patient-centered regimen is considered optimal. Age, pharmacokinetics, bleeding phenotype, joint status, adherence, physical activity, personal goals are all factors that should be considered when individualizing therapy. In the past 10 years, many innovations in the diagnostic and treatment options were presented as being either approved or in development, thus helping clinicians to improve the standard-of-care for patients with hemophilia. Recombinant factors still remain the standard of care in hemophilia, however they pose a challenge to treatment adherence because they have short half-life, which where the extended half-life (EHL) factors come with the solution, increasing the half-life to 96 hours. Gene therapies have a promising future with proven beneficial effects in clinical trials. We present and critically analyze in the current manuscript the pros and cons of all the major discoveries in the diagnosis and treatment of HA and HB, as well as identify key areas of hemophilia research where improvements are needed.

A new hemophilia carrier nomenclature to define hemophilia in women and girls: Communication from the SSC of the ISTH

Hemophilia A and B predominantly attracts clinical attention in males due to X-linked inheritance, introducing a bias toward female carriers to be asymptomatic. This common misconception is contradicted by an increasing body of evidence with consistent reporting on an increased bleeding tendency in hemophilia carriers (HCs), including those with normal factor VIII/IX (FVIII/IX) levels. The term HC can hamper diagnosis, clinical care, and research. Therefore, a new nomenclature has been defined based on an open iterative process involving hemophilia experts, patients, and the International Society on Thrombosis and Haemostasis (ISTH) community. The resulting nomenclature accounts for personal bleeding history and baseline plasma FVIII/IX level. It distinguishes five clinically relevant HC categories: women/girls with mild, moderate, or severe hemophilia (FVIII/IX >0.05 and <0.40 IU/ml, 0.01-0.05 IU/ml, and <0.01 IU/ml, respectively), symptomatic and asymptomatic HC (FVIII/IX ≥0.40 IU/ml with and without a bleeding phenotype, respectively). This new nomenclature is aimed at improving diagnosis and management and applying uniform terminologies for clinical research.

Regulation and importance of factor VIII levels in hemophilia A carriers

PURPOSE OF REVIEW

To summarize the recent literature related to female hemophilia A carriers with respect to prevalence in the population, the impact of baseline factor VIII levels and other influences on bleeding phenotype, and clinical management needs.

RECENT FINDINGS

Many female hemophilia A carriers are at risk for abnormal bleeding, yet they are underrecognized by healthcare providers and their bleeding symptoms are underreported. Low FVIII levels are consistently associated with clinically significant bleeding and correlate well with skewed X chromosome inactivation (XCI). Most interestingly, bleeding tendency is also observed in some hemophilia A carriers with normal factor VIII levels and requires further investigation. Well controlled studies investigating peripartum and periprocedural FVIII levels and adequate hemostatic treatment are necessary to inform management guidelines.

SUMMARY

Prevalence and bleeding tendency of hemophilia A carriers remain underreported, despite a significant proportion having low FVIII levels. Skewed XCI may explain low FVIII but does not explain the bleeding risk encountered in a larger proportion of hemophilia A carriers with random XCI and borderline/normal FVIII.

Haemophilia

Haemophilia A and B are rare congenital, recessive X-linked disorders caused by lack or deficiency of clotting factor VIII (FVIII) or IX (FIX), respectively. The severity of the disease depends on the reduction of levels of FVIII or FIX, which are determined by the type of the causative mutation in the genes encoding the factors (F8 and F9, respectively). The hallmark clinical characteristic, especially in untreated severe forms, is bleeding (spontaneous or after trauma) into major joints such as ankles, knees and elbows, which can result in the development of arthropathy. Intracranial bleeds and bleeds into internal organs may be life-threatening. The median life expectancy was ~30 years until the 1960s, but improved understanding of the disorder and development of efficacious therapy based on prophylactic replacement of the missing factor has caused a paradigm shift, and today individuals with haemophilia can look forward to a virtually normal life expectancy and quality of life. Nevertheless, the potential development of inhibitory antibodies to infused factor is still a major hurdle to overcome in a substantial proportion of patients. Finally, gene therapy for both types of haemophilia has progressed remarkably and could soon become a reality.

Pharmacokinetic-guided prophylaxis improved clinical outcomes in paediatric patients with severe haemophilia A

BACKGROUND

The traditional weight-based dosing regimen can lead to under- or overdosage due to the interindividual variability of pharmacokinetic (PK) parameters. PK-guided prophylaxis can be an optimized therapy choice.

AIM

This study aimed to investigate the clinical outcomes of PK-guided prophylaxis in 46 boys with severe haemophilia A.

METHODS

Forty-six boys with severe haemophilia A were enrolled in Beijing Children's Hospital. The PK tests were performed using a five-point assay. PK parameters were calculated using WinNonlin software. The dosing regimen and bleeding rates recorded during the observation period. The adjustment was based on PK evaluation, bleeding details, doctor's advice and patients' choice.

RESULTS

The half-life time, in vivo recovery and clearance of Kovaltry were 14.34 ± 2.68 h, 1.78 ± 0.29 kg/dl and 3.38 ± 0.94 ml/kg/h, respectively. In 18 patients without any change in the dosing regimen, the trough level was 4.0 ± 2.41 IU/dl and the bleeding rates were similar after PK tests. For patients with a higher trough level after adjustment, higher dose and frequency were observed, as well as a higher trough level. Also, reduced annual bleeding rate (ABR), annual joint bleeding rate and annual spontaneous bleeding rate (ASBR) were found. In five patients with a reduced trough level, lower infusion frequency and weekly coagulation factor VIII (FVIII) consumption were observed, with no statistically significant difference in ABR and ASBR.

CONCLUSION

PK-guided prophylaxis can help haemophiliac patients improve quality of life by decreasing bleeds with appropriate FVIII consumption and reducing infusion frequency without increments in bleeds, thus optimizing haemophilia treatment.

High prevalence of overweight/obesity in adult persons with hemophilia in Utah and a review of the literature

: The objectives of this study were firstly to determine the prevalence of overweight/obesity in adult persons with hemophilia in Utah, and to explore the association between age, disease severity and race with body mass index (BMI), and secondly to provide recent data on the prevalence of overweight/obesity in the hemophilia population via a review of the literature. We conducted a retrospective cross section study of adult persons with hemophilia who were seen at a Utah hemophilia treatment center from 1 January 2017 to 31 December 2019. The electronic database PubMed was searched for studies with observation periods from 1 January 2012 to 31 December 2019. The age-adjusted prevalence for overweight/obesity in the adult Utah hemophilia population was higher than the overall Utah population and the general US population. After adjusting for race and age, mild hemophilia was associated with a 7.7% higher BMI (95% confidence interval, 0.023-15.98%, P < 0.05). Review of the literature demonstrated high levels of overweight/obesity in hemophilia communities globally with considerable heterogeneity between studies. Despite increasing awareness, prevalence of overweight/obesity in the hemophilia population remains high in comparison with the general population. There is a critical need to address this issue acutely at hemophilia treatment centers due to the considerable burden of obesity.

Validation of a perioperative population factor VIII pharmacokinetic model with a large cohort of pediatric hemophilia a patients

AIMS

Population pharmacokinetic (PK) models are increasingly applied to perform individualized dosing of factor VIII (FVIII) concentrates in haemophilia A patients. To guarantee accurate performance of a population PK model in dose individualization, validation studies are of importance. However, external validation of population PK models requires independent data sets and is, therefore, seldomly performed. Therefore, this study aimed to validate a previously published population PK model for FVIII concentrates administrated perioperatively.

METHODS

A previously published population PK model for FVIII concentrate during surgery was validated using independent data from 87 children with severe haemophilia A with a median (range) age of 2.6 years (0.03-15.2) and body weight of 14 kg (4-57). First, the predictive performance of the previous model was evaluated with MAP Bayesian analysis using NONMEM v7.4. Subsequently, the model parameters were (re)estimated using a combined dataset consisting of the previous modelling data and the data available for the external validation.

RESULTS

The previous model underpredicted the measured FVIII levels with a median of 0.17 IU mL^-1 . Combining the new, independent and original data, a dataset comprising 206 patients with a mean age of 7.8 years (0.03-77.6) and body weight of 30 kg (4-111) was obtained. Population PK modelling provided estimates for CL, V1, V2, and Q: 171 mL h^-1  68 kg^-1 , 2930 mL 68 kg^-1 , 1810 mL 68 kg^-1 , and 172 mL h^-1  68 kg^-1 , respectively. This model adequately described all collected FVIII levels, with a slight median overprediction of 0.02 IU mL^-1 .

CONCLUSIONS

This study emphasizes the importance of external validation of population PK models using real-life data.

Pharmacokinetic study of Kovaltry in thirty-five pediatric patients aged <12 years with severe hemophilia A

BACKGROUND

Kovaltry (BAY81-8973) is an unmodified full-length factor VIII (FVIII) concentrate that enhances the pharmacokinetic (PK) profiles as compared to some other standard half-life time FVIII concentrates. However, the PK of Kovaltry in haemophiliac patients aged <12 years has not been reported previously.

AIM

To investigate the pharmacokinetics and clinical outcomes of Kovaltry in 35 paediatric patients aged <12 years.

METHODS

A total of 35 boys with severe haemophilia A were enrolled from August 2019 to May 2020 in Beijing Children's Hospital. After 72-hour washout, PK tests were performed post-infusion of 50 IU/kg Kovaltry in a five-timepoint assay. WinNonlin software was used to generate individual PK parameters. The dose, frequency and bleeding details were collected within the first 6 months after switching to Kovaltry from other FVIII concentrates.

RESULTS

Compared to the blood group O, patients with blood group non-O showed longer mean half-life (t_1/2 ) (p < .01), lower mean clearance (CL) (p = .01) and similar in vivo recovery (IVR) (p = .51). Higher von Willebrand factor antigen (VWF:Ag) level was correlated to longer t_1/2 (p < .0001) and lower CL (p < .01). IVR was correlated to body mass index (BMI) (p < .0001). Patients with trough level >3 IU/dL demonstrated lower annual bleeding rate (ABR) (p < .01), annual joint bleeding rate (AJBR) (p < .01) and annual spontaneous bleeding rate (ASBR) (p < .01).

CONCLUSION

This study firstly reported the PK profiles of Kovaltry in 35 paediatric patients <12 years old. The great inter-individual variability of PK parameters was also confirmed in these patients. VWF:Ag and blood group were major influencing factors of t_1/2 and CL of Kovaltry, while BMI was a vital predictor for IVR. Patients with high trough FVIII level in routine prophylaxis had reduced bleeding rates.

ABO incompatibility and mild factor VIII deficiency in the neonate: Not too much of a problem but a challenge on ECMO

Coagulopathy and bleeding on extracorporeal membrane oxygenation (ECMO) contribute to a worse outcome, and hyperbilirubinemia is an additional threat for newborn babies. We report a case of a newborn boy with congenital diaphragmatic hernia (CDH) associated with ABO incompatibility and an inherited mild hemophilia A. Due to respiratory failure he needed ECMO on his first day of life. During ECMO an exchange transfusion was performed after an extensive hyperbilirubinemia had evolved. Thereafter severe bleeding occurred, and a very low factor VIII level was found causative for that. After factor VIII substitution bleeding was under control and the baby eventually could be weaned from ECMO, underwent corrective surgery, and recovered.

Current challenges for men and women with mild-to-moderate haemophilia

Current treatments in the field of haemophilia are changing the phenotype of many patients with severe haemophilia to that of mild haemophilia. Despite this improvement, those with mild-to-moderate haemophilia A and haemophilia B continue to experience unmet needs. Whereas some patients with mild-to-moderate haemophilia experience similar complications to those of patients with severe haemophilia, they possess several unique attributes. These include a challenging diagnosis and variability in bleeding symptoms and treatment needs. In addition, haemophilia is an under-recognized condition in women even though many women with mild-to-moderate haemophilia experience the same symptoms and complications as men with haemophilia. These women also have their own unique challenges with this disease. This supplement highlights many of the unmet needs in men and women with mild-to-moderate haemophilia. The conclusions of each of these papers reinforce the need for additional research and resources for this patient population.

Sexism in the management of bleeding disorders

Sexism has been an issue in bleeding disorders for centuries. Women with bleeding disorders have been underrecognized and underdiagnosed. Those who are diagnosed often experience delays in diagnosis and feel that their symptoms are dismissed or minimized. Several factors contribute to this sexism. Historically, the clinical and research focus within the bleeding disorder community has been on men and hemophilia. Von Willebrand disease, a disease that has long been recognized as affecting women, is much more common than hemophilia, yet has significantly fewer resources devoted to it. The lack of knowledge and comfort that patients and health care providers have regarding menstruation compounds the issue, as heavy menstrual bleeding is one of the most common symptoms seen in women with bleeding disorders. Stemming from the universal stigmatization of periods, this lack of comfort and knowledge results in fewer women seeking care, fewer health care providers addressing the issue, and fewer women getting the care they deserve. Progress has been made, with many organizations dedicating resources to improving the care of these women. The road is long, and much more work is needed to ensure that women with bleeding disorders receive the care they deserve.

Assessing the Performance of Extended Half-Life Coagulation Factor VIII, FC Fusion Protein by Using Chromogenic and One-Stage Assays in Saudi Hemophilia A Patients

Background

The one-stage assay is the most common method to measure factor VIII activity (FVIII : C) in hemophilia A patients. The chromogenic assay is another two-stage test involving purified coagulation factors followed by factor Xa-specific chromogenic substrate.

Aim

This study aimed to assess the discrepancy and correlation between the chromogenic and one-stage assays in measuring FVIII : C levels in hemophilia patients receiving Extended Half-Life Elocta® as a recombinant extended half-life coagulation factor.

Methods

We performed a study comparing the measurements of FVIII : C levels by the chromogenic versus the one-stage assays at different drug levels. Data of FVIII : C levels, dosage, and the time interval from administration to measurement were retrieved from the hospital records. The correlation, mean differences, and discrepancy between the two assays were calculated. The linear regression analysis was used to predict the time interval till reaching 1% FVIII : C.

Results

Fourteen patients with 56 samples were included in the study. Of them, 13 patients were receiving Elocta® as a prophylactic, while one was receiving Elocta® on demand. One-third of these samples showed a discrepancy between the chromogenic and one-stage assays. The two assays were well correlated. Mean differences were significant at the individual and the time interval level. The time since the last Elocta® injection could significantly predict FVIII : C levels (β = 0.366, P < 0.001).

Conclusion

Our findings suggested a significant difference between both methods; the FVIII : C levels measured by the one-stage assay were less than those estimated by the chromogenic assay. However, the measurements of FVIII levels by the two assays were well correlated but discrepant in one-third of the samples. The levels of FVIII : C reach 1% after 5.4 days since the last Elocta® administration.

Non-severe haemophilia: Is it benign? - Insights from the PROBE study

INTRODUCTION

There are limited data on the impact of haemophilia on health status and health-related quality of life (HRQL) in people with non-severe (mild and moderate) haemophilia.

AIM

To evaluate the health status of people living with mild or moderate haemophilia.

METHODS

Data on respondents with no bleeding disorder (NoBD), mild and moderate haemophilia patients were drawn from the PROBE study. Respondents were enrolled using network patient organizations. This analysis was performed as a cross-sectional study. Primary outcomes were reported bleeding, acute and chronic pain, activities of daily living and HRQL.

RESULTS

A total of 862 respondents with NoBD (n = 173), mild (n = 102) and moderate (n = 134) haemophilia were eligible, with a median age of 33, 42 and 43, respectively. In relation to haemophilia-related sequalae, 53% of male and 29% of female patients with mild and 83% of males with moderate haemophilia had more than 2-3 bleeds in the last 12 months. Reporting of acute and chronic pain is less in those with NoBD compared to the mild and moderate cohorts for both genders. Multivariate analysis demonstrates significant reductions in quality of life using VAS, EQ-5D-5L and PROBE for males with mild and moderate haemophilia (P ≤ .001) with only PROBE indicating a significant reduction for females with mild (P = .002).

CONCLUSION

People affected by mild or moderate haemophilia report a significant HRQL impact due to haemophilia-related bleeding. Future research is needed to identify the optimal care management of patients with mild and moderate haemophilia.

Management of von Willebrand disease with a factor VIII-poor von Willebrand factor concentrate: Results from a prospective observational post-marketing study

BACKGROUND

A triple-secured plasma-derived von Willebrand factor (pdVWF) almost devoid of factor VIII (FVIII):WILFACTIN® , was approved in France in 2003, and then in other countries for the treatment of patients with von Willebrand disease (VWD).

OBJECTIVE

To investigate long-term safety and efficacy of the product in real-life over the first 5 post-approval years.

PATIENTS/METHODS

This prospective, observational, national post-marketing study (PMS) enrolled patients of all ages and VWD types. Patients were observed for up to 3 years and treated for one or more occasions. Efficacy was assessed for each major event. Breakthrough bleeding rate 3 days post-infusion and annualized bleeding rate (ABR) were also evaluated for long-term prophylaxis.

RESULTS

Overall, 155 of 174 patients enrolled from 31 centers were eligible for efficacy assessment. Most patients (76.8%) were severely affected (VWF:RCo ≤ 15 IU/dL). They were treated for 743 bleeds and 140 surgeries including childbirth. Efficacy outcomes were excellent/good for 98.2% of 56 major surgeries and 94.0% of 67 major bleeds. Approximately 75% of 49 major mucosal bleeds were effectively managed without FVIII co-administration. In 32 patients receiving prophylaxis, breakthrough bleeding occurred in 1.5% of infusions and median ABR was 1.0 for 20 patients treated ≥ 12 months. Excellent tolerability was confirmed with no safety concerns. No thrombotic events were observed.

CONCLUSIONS

Results from this PMS increase the clinical experience of a FVIII-poor pdVWF in patients of all ages and VWD types including those with thrombotic risk factors and emphasize that giving FVIII is not always mandatory to effectively treat patients with severe VWD.

Influence of blood group, von Willebrand factor levels, and age on factor VIII levels in non-severe haemophilia A

BACKGROUND

Data on the effect of ABO blood group (ABO), von Willebrand factor (VWF) levels, and age on factor VIII (FVIII) in non-severe haemophilia A (HA) is scarce.

OBJECTIVE

To investigate if ABO, VWF levels, and age have an influence on the variability of FVIII levels and consequently on the assessment of severity in non-severe HA.

PATIENTS/METHODS

Eighty-nine patients with non-severe HA and 82 healthy controls were included. Data on ABO was collected and FVIII clotting activity (FVIII:C) with one-stage clotting assay (FVIII:C OSA) and chromogenic substrate assay (FVIII:C CSA), FVIII antigen (FVIII:Ag) and VWF antigen (VWF:Ag) and activity (VWF:Act) were determined.

RESULTS

In HA, FVIII:C OSA and CSA and FVIII:Ag were not different between non-O (n = 42, median 15.5, interquartile range 10.4-24.0; 10.0, 6.8-26.0 and 15.2, 10.7-24.9) and O (n = 47, 14.1, 9.0-23.0; 10.0, 5.0-23.0 and 15.2, 9.3-35.5), whereas in healthy controls, non-O individuals had significantly higher FVIII levels.

FVIII

C showed no relevant correlation with VWF levels in HA, but we observed strong correlations in healthy controls. Age had only a minor influence in HA, but had a considerable impact on FVIII:C in healthy controls. In multivariable regression analysis ABO, VWF:Ag and age were not associated with FVIII:C in HA, whereas this model explained 61.3% of the FVIII:C variance in healthy controls.

CONCLUSIONS

We conclude that in non-severe HA ABO and VWF levels do not substantially influence the variability of FVIII levels and age has only minor effects on it, which is important information for diagnostic procedures.

Hemophilia management: Huge impact of a tiny difference

Hemophilia A and B are inherited X-linked disorders of hemostasis, associated with an increased bleeding tendency. Patients with severe hemophilia have undetectable clotting factor levels and experience spontaneous bleeds. In patients with nonsevere hemophilia, the clotting factor levels are 2% to 40% of normal and bleeds predominantly occur after provocative events such as trauma and surgery. Despite this milder phenotype, patients with nonsevere hemophilia may suffer from considerable morbidity and have an increased mortality risk. However, many aspects of the course of disease and treatment remain unclear. Information on the factors influencing interindividual differences in bleeding phenotype is lacking, and misdiagnosis may occur due to assay discrepancies in the diagnostic workup. Desmopressin is the preferred treatment modality, but some patients and indications require treatment with clotting factor concentrates. This may elicit inhibitor formation, which is associated with an increased burden of disease and a higher mortality rate. It has been found that patients with nonsevere hemophilia A carry a lifelong risk for this serious complication. In this review, we provide an overview of the current knowledge of the diagnosis and management of nonsevere hemophilia. A report of science presented at the International Society on Thrombosis and Haemostasis 2019 Annual Congress is also provided.

Global coagulation assays in hemophilia A: A comparison to conventional assays

BACKGROUND

Global assays measure the interactions of coagulants, anticoagulants, and platelets on thrombin generation and may reflect the comprehensive coagulation potential in patients with hemophilia better than conventional assays.

OBJECTIVES

The objectives of the current study were to investigate the value of global assays for measuring and monitoring the coagulation potential of patients with hemophilia A (HA).

PATIENTS/METHODS

Rotational thromboelastometry, thrombin generation assay (TGA), and activated partial thromboplastin time (APTT) clot waveform analysis were investigated in a cohort of patients with severe, moderate, and mild HA and compared with conventional assays.

RESULTS

The maximum velocity (MaxVel) parameter of modified thromboelastometry analysis, initiated by tissue factor and in the presence of corn trypsin inhibitor (CTI), had 92% sensitivity and 95% specificity for hemophilia diagnosis. The MaxVel also strongly correlated with factor VIII (FVIII) levels of patients with HA (r = .805, P < .0001). CTI improved the sensitivity of TGA, providing more accurate results. In particular, peak height parameter of platelet-rich plasma samples with CTI had a sensitivity and specificity of 100% and 94%, respectively, in all patients with HA. APTT clot waveform analysis minimum value of first derivative (Min1) and minimum value of second derivative (Min2) parameters (representing speed and acceleration of clot formation, respectively) were sensitive and correlated more strongly with FVIII levels than APTT clotting times did (Min1: r = 0.786, P < 0.0001; Min2: r = 0.759, P < 0.0001; APTT: r = -0.513, P = 0.001).

CONCLUSIONS

The sensitivity and specificity of the global assays was method dependent. Correlation between clinical end points and thrombin generation might also be valuable in the era of non-factor replacement therapy.

Fundamentals for a Systematic Approach to Mild and Moderate Inherited Bleeding Disorders: An EHA Consensus Report

Healthy subjects frequently report minor bleedings that are frequently ‘background noise’ of normality rather than a true disorder. Nevertheless, unexpected or unusual bleeding may be alarming. Thus, the distinction between normal and pathologic bleeding is critical. Understanding the underlying pathologic mechanism in patients with an excessive bleeding is essential for their counseling and treatment. Most of these patients with significant bleeding will result affected by non-severe inherited bleeding disorders (BD), collectively denominated mild or moderate BD for their relatively benign course. Unfortunately, practical recommendations for the management of these disorders are still lacking due to the current state of fragmented knowledge of pathophysiology and lack of a systematic diagnostic approach. To address this gap, an International Working Group (IWG) was established by the European Hematology Association (EHA) to develop consensus-based guidelines on these disorders. The IWG agreed that grouping these disorders by their clinical phenotype under the single category of mild-to-moderate bleeding disorders (MBD) reflects current clinical practice and will facilitate a systematic diagnostic approach. Based on standardized and harmonized definitions a conceptual unified framework is proposed to distinguish normal subjects from affected patients. The IWG proposes a provisional comprehensive patient-centered initial diagnostic approach that will result in classification of MBD into distinct clinical-pathological entities under the overarching principle of clinical utility for the individual patient. While we will present here a general overview of the global management of patients with MBD, this conceptual framework will be adopted and validated in the evidence-based, disease-specific guidelines under development by the IWG.

Burden of mild haemophilia A: Systematic literature review

Introduction

Although the clinical manifestations of severe haemophilia A (HA) are well studied, the challenges, if any, of living with mild HA are not clearly delineated to date.

Aim

To assess available evidence of clinical risks and societal/economic impacts of disease in adult patients with mild HA using a systematic literature review.

Methods

Prespecified study selection criteria were applied in a comprehensive literature search. Included studies varied in design and reported outcomes of interest for adults (≥13 years of age) with mild HA.

Results

Seventeen studies with a total of 3213 patients met eligibility criteria (published or presented in English, 1966‐2017). Most studies were observational, and the outcomes reported were too sparse and dissimilar to support a formal meta‐analysis. Mean annual bleeding rates ranged from 0.44 to 4.5 episodes per patient per year. Quality of life (QoL; SF‐36 General Health) was impacted compared to healthy controls. Health care costs and productivity were seldom assessed and no robust comparisons to healthy controls were available.

Conclusion

Quantifying outcomes for adult patients with mild HA remains challenging, with estimates of key QoL and cost data often based on small data sets and without comparison to population norms. Therefore, the clinical impact of mild haemophilia may be under‐represented and unmet needs may remain unaddressed. As paradigm‐changing therapies for HA emerge, stronger knowledge of mild HA can guide the development of care options that minimize burden and enhance the QoL for this segment of the haemophilia community, and for the haemophilia community in totality.