Inhibitors in haemophilia A and B: Management of bleeds, inhibitor eradication and strategies for difficult-to-treat patients

Immune Tolerance Induction With a Recombinant Factor VIII Fc in Haemophilia A: Data From a Chart Review Study

OBJECTIVE

To report data from an ITI chart review study (NCT03951103) for first-time and rescue ITI with recombinant factor VIII Fc fusion protein (rFVIIIFc) in persons with haemophilia A.

METHODS

Retrospective and prospective real-world data are reported from a non-interventional, multicentre study of patients who had been or were currently being treated with rFVIIIFc ITI. ITI treatment outcome (defined by investigators) and regimens are reported.

RESULTS

Forty-one patients from 16 sites were included. First-time ITI was used in 24 patients; 16 had an ITI outcome at study end. Thirteen patients (81.3%) had ITI success, and three had failure. Median (range) rFVIIIFc consumption was 300 (61-2800) IU/kg/week, and most (70.8%) used ≤ 300 IU/kg/week. The vast majority of patients (87.5%) received less than daily ITI. Rescue ITI was used in 17 patients; 16 had an ITI outcome at study end. Eight patients (50.0%) had ITI success/partial success, seven had failure, and one withdrew early. Median (range) rFVIIIFc consumption was 536 (98-1435) IU/kg/week; 35.3% used ≤ 300 IU/kg/week and 52.9% used > 500 IU/kg/week. Most patients (64.7%) received daily ITI.

CONCLUSION

ITI with rFVIIIFc is likely to be successful in first-time ITI patients and is an effective option for those who have previously experienced ITI failure.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03951103.

Concizumab, a Non-Replacement Therapy for Persons with Hemophilia with Inhibitors

Despite enormous progress in the development of therapeutic agents for persons with hemophilia A and B (HA, HB), several unmet needs persist. These are disease- and treatment-related. Prophylaxis with clotting factor replacement is the gold standard, but not feasible in HA and HB with inhibitors. Whereas persons with HA with inhibitors can receive prophylaxis with a factor-mimicking agent, emicizumab, there is no recommendation for the agents to use as prophylaxis in persons with HB with inhibitors as there are no available molecules. Concizumab is a novel, subcutaneous prophylaxis option in persons with HA or HB with inhibitors that can potentially improve long-term outcomes. Here, we review the available data on concizumab and discuss its possible positioning in the armamentarium to treat hemophilia with inhibitors.

Outcomes of immune tolerance induction with rituximab to eradicate high-titer inhibitor of hemophilia A: depicted by exponential decay model and the gene expression profile of different outcomes by RNA-sequencing

BACKGROUND

Eradication of inhibitors is still a desirable goal for patients with hemophilia A inhibitors. Combining rituximab with immune tolerance induction (ITI) is the secondline regimen, but data and predictors are limited.

OBJECTIVES

To evaluate the efficacy of ITI-rituximab and to identify the predictors of prognosis.

METHODS

In total, 76 children with high-titer inhibitor prospectively using low-dose ITI together with 1-3 round(s) of rituximab were evaluated for outcomes: success or failure and rapidity (rapid or slow) of inhibitor negativity (ie, inhibitor titers turned negative, inhibitor negativity [IN]). The whole-transcriptome RNA-sequencing (RNA-seq) was used to analyze the gene expression profile of 4 failure patients (excluding F8 large deletion) and 4 rapid success-IN patients.

RESULTS

Success IN was achieved in 41 of 76 (53.9%) patients after first-round of rituximab, 50 of 76 (65.8%) after second-round of rituximab, and 51 of 76 (67.1%) after third-round of rituximab. Profile of inhibitor decay followed an exponential decay curve. Time to a given inhibitor titer during ITI-rituximab could be estimated by the model t=ln(Y0-PlateauY-Plateau)k. The newly observed poor prognostic factors included relapse after the first-round of rituximab and early occurence of poor-outcome events.. RNA-seq analysis showed 186 upregulated differential expressed genes (DEGs) and 176 downregulated DEGs in failure subjects compared with those in patients with rapid success IN. The upregulated DEGs included CXCL8, NLRP6, CHI3L1, CLEC9A, THBD, and PROS1. The downregulated DEGs included STAT1, TLR7, C1Q, C2, IDO1, and CD38.

CONCLUSION

Success IN was achieved in 67% of children with hemophilia A with high-titer inhibitor treated by ITI-rituximab. A model based on the profile of inhibitor-titer decay can be used for predicting outcomes. Humoral immune response and complement and coagulation cascades may act as signals that influence ITI outcomes (ClinicalTrials.gov: NCT03598725).

Gene therapy as an innovative approach to the treatment of hemophilia B-a review

Hemophilia B is a disease that affects the human coagulation system, causing the absence or deficiency of coagulation factor IX, which may manifest itself in uncontrolled bleeding that is life-threatening to patients. Due to its inheritance, the disease more often affects men, and the severity of symptoms directly correlates with the concentration of the missing factor IX; hence, the aim of therapy is to maintain it at a level that allows for sufficient hemostasis. The basic model of treatment offered to patients is based on primary prevention with coagulation factor IX with a prolonged half-life, which, however, does not solve the numerous problems faced by patients. An innovative proposal that, despite initial concerns, is becoming more and more popular every day is the recently approved genetic therapy in Europe, which uses viral vectors to transfer the correct gene that encodes coagulation factor IX. The introduction of a recombinant gene in place of its defective counterpart seems to be a promising solution and the beginning of a new era in which genetic therapies have a chance to develop their full potential and replace existing therapeutic regimens.

Thrombin Generation Assay to Support Hematologists in the Era of New Hemophilia Therapies

Hematology laboratories have traditionally monitored hemophilia replacement therapy by measuring coagulation factors before and after infusion. However, new drugs that do not rely on the replacement of the deficient factor require new approaches to laboratory monitoring, as factor VIII (FVIII) or factor IX (FIX) assays are no longer adequate. Non-factor therapies come in many different forms, that have one thing in common: they all increase thrombin generation. Their main adverse effect is thrombosis which may occur when too much thrombin is formed. This is the perfect mirror image of anticoagulant treatment, which always diminishes the amount of thrombin formed and has bleeding as its main adverse effect. Thrombin-forming capacity is decreased in congenital bleeding disorders and increased in prothrombotic conditions, indicating it governs bleeding and thrombosis. Therefore, the thrombin generation assay (TGA) is a logical tool for monitoring non-factor therapies, offering a comprehensive assessment of hemostatic balance. TGA identifies patients with severe bleeding, helps to optimize bypassing therapy, and detects hypercoagulability, making it ideal for guiding and monitoring hemophilia treatment with non-factor therapies. It also assesses the efficacy and safety of combined therapies, including non-factor therapies with bypassing agents or FVIII/FIX concentrates. The purpose of this paper is to review the current state of knowledge regarding the use of TGA to monitor novel hemophilia therapies. It will address controversies, limitations, and knowledge gaps related to the integration of TGA into personalized medicine in routine clinical practice.

Haemophilia

Haemophilia A and B are congenital X-linked bleeding disorders resulting from deficiencies in clotting factors VIII (haemophilia A) and IX (haemophilia B). Patients with severe deficiency, defined as having less than 1% of normal plasma factor activivity, often have spontaneous bleeding within the first few years of life. Those with moderate and mild deficiencies typically present with post-traumatic or post-surgical bleeding later in life. A high index of suspicion and measurement of factor activity in plasma facilitates early diagnosis. In the 21st century, therapeutic advances and comprehensive care have substantially improved both mortality and morbidity associated with these conditions. Management strategies for haemophilia include on-demand treatment for bleeding episodes and all surgeries and regular treatment (ie, prophylaxis) aimed at reducing bleeds, morbidity, and mortality, thereby enhancing quality of life. Treatment options include factor replacement therapy, non-replacement therapies that increase thrombin generation, and gene therapies that facilitate in vivo clotting factor synthesis. The therapies differ in their use for prophylaxis and on-demand treatment, the mode and frequency of administration, duration of treatment effect, degree of haemostatic protection, and side-effects. Monitoring the effectiveness of these prophylactic therapies involves assessing annual bleeding rates and joint damage. Personalised management strategies, which align treatment with individual goals (eg, playing competitive sports), initiated at diagnosis and maintained throughout the lifespan, are crucial for optimal outcomes. These strategies are facilitated by a multidisciplinary team and supported by clinician-led education for both clinicians and patients.

Non-factor Therapies for Hemophilia: Achievements and Perspectives

Non-factor replacement therapies (NFTs) have been developed to address the limitations of conventional replacement therapies, aiming to improve hemostasis and provide enhanced protection against bleeding episodes and long-term joint damage for patients both with and without inhibitors. Factor VIII (FVIII)-mimetic agents, such as emicizumab, have transformed the management of hemophilia A with inhibitors, offering a lower treatment burden and an effective alternative for those without inhibitors as well. Rebalancing agents, including anti-tissular factor pathway inhibitor agents (concizumab and marstacimab) and serpin inhibitors like fitusiran, have shown promising efficacy for patients with hemophilia B with inhibitors and other hemophilia subtypes. Administered subcutaneously, NFTs generate stable thrombin levels and feature a long half-life, which can shift severe hemophilia toward a milder phenotype. These therapies are effective regardless of inhibitor status and hold potential for application in other bleeding disorders. Evaluating the potential thrombotic risk after implementing mitigation measures, along with the development of anti-drug antibodies (ADAs), remain critical areas for further analysis. NFTs pose additional challenges due to their complex mechanism of action and the absence of a standardized laboratory assessment method. Unresolved issues include optimal management strategies for major surgeries and tailored approaches for safe use in older populations. This review highlights the progress and future potential of NFTs in treating persons with hemophilia.

Safety and efficacy of myofascial release therapy in the treatment of patients with hemophilic ankle arthropathy. Single-blind randomized clinical trial

BACKGROUND

Hemophilia is characterized by degenerative joint damage. Patients with hemophilic arthropathy present joint damage, reduced range of motion, and decreased strength and functional capacity. Myofascial release therapy aims to decrease pain and improve tissue mobility and functionality.

OBJECTIVES

To evaluate the safety and efficacy of myofascial release therapy in patients with hemophilic ankle arthropathy.

METHOD

Single-blind randomized controlled trial. Fifty-eight adult patients with hemophilia were randomly allocated to the experimental group (myofascial release therapy with foam roller) or the control group (no intervention whatsoever). The daily home protocol of myofascial release therapy for the lower limbs using a foam roller lasted eight consecutive weeks. The primary variable was the safety of myofascial release therapy (weekly telephone follow-up). The secondary variables were pain intensity (visual analog scale), range of motion (goniometer), functional capacity (2-Minute Walk Test) and muscle strength (dynamometer), at baseline and at 8 and 10 weeks.

RESULTS

During the experimental phase, none of the patients in the experimental group developed ankle hemarthrosis. There were statistically significant changes in time*group interaction in ankle dorsal flexion (F[1.75] = 10.72; p < .001), functional capacity (F[1.16] = 5.24; p = .009) and gastrocnemius strength (F[2] = 26.01; p < .001). The effect size of the changes after the intervention was medium-large in pain intensity (d = -1.77), functional capacity (d = 1.34) and gastrocnemius strength (d = 0.76).

CONCLUSION

Myofascial release therapy is a safe form of physical therapy for patients with hemophilia. Myofascial release therapy can effectively complement prophylactic pharmacological treatment in patients with hemophilic arthropathy, improving range of motion in dorsal flexion, functional capacity and gastrocnemius strength.

Advances in Development of Drug Treatment for Hemophilia with Inhibitors

Patients with hemophilia A and B who have inhibitors face limited treatment options, because replacement therapy with clotting factor VIII or IX concentrates is ineffective, particularly for patients with high-titer inhibitors. Current mainstay therapies include immune tolerance induction (through frequent injections of clotting factor VIII or IX concentrates) to eradicate inhibitors and bypassing agents (such as recombinant activated clotting factor VII and activated prothrombin complex concentrates) for the prevention and treatment of bleeding episodes. The use of these agents typically requires intravenous injections and sometimes hospitalization, which can be burdensome for patients. More recently, emicizumab, a bispecific antibody that mimics the function of activated clotting factor VIII, has demonstrated favorable efficacy for prophylaxis in patients with hemophilia A and inhibitors, representing a promising new therapeutic strategy. Ongoing research aims to discover and develop easy-to-use nonfactor agents for managing hemophilia with inhibitors. This review summarizes the current understanding of the pathophysiology of inhibitor development in hemophilia, outlines existing treatment options, and discusses advancements in novel therapeutic biologics, including a recombinant activated clotting factor VII variant (marzeptacog alfa), a new bispecific antibody (Mim8), antitissue factor pathway inhibitor antibodies (concizumab and marstacimab), and small interfering RNA targeting antithrombin (fitusiran). All of these agents are administered subcutaneously, with some offering the convenience of less frequent dosing (e.g., weekly or monthly). These potential drug candidates may provide significant benefits for the prophylaxis or treatment of bleeding disorders in patients with hemophilia and inhibitors.

International Society on Thrombosis and Haemostasis Clinical Practice Guideline for Treatment of Congenital Haemophilia-A Critical Appraisal

INTRODUCTION

Evidence-based clinical practice guidelines drive optimal patient care and facilitate access to high-quality treatment. Creating guidelines for rare diseases such as haemophilia, where evidence does not often come from randomized controlled trials but from non-randomized and well-designed observational studies and real-world data, is challenging. The methodology used for assessing available evidence should consider this critical fact. In formulating guidelines, it is essential to include treatment goals and patient preference.

AIM

This paper comprehensively critiques, against this background, the recommendations of the ISTH clinical practice guidelines for the treatment of haemophilia.

METHODS

Each recommendation was critically reviewed against available evidence as well as existing guidelines and commented upon for its scientific validity, impact on clinical practice and access to care globally. The validity of the way in which the GRADE methodology was applied to existing evidence was also assessed.

RESULTS

The critique provided shows that these recommendations have major limitations: they did not state treatment goals and contradict existing guidelines; opportunities for providing access to innovation were missed when the therapeutic benefits of the products approved in the last decades were not included. A major reason for this is the inappropriate adoption of the GRADE methodology without adaptations and without considering treatment goals and patient-relevant outcomes.

CONCLUSION

These recommendations may mislead healthcare professionals, payers and governments and therefore cannot serve the patient community well. They setback the advances made in haemophilia care because they overlook important available evidence and do not guide clinical practice to contemporary standards.

Clinical validation and application of targeted long-range polymerase chain reaction and long-read sequencing-based analysis for hemophilia: experience from a hemophilia treatment center in China

BACKGROUND

Targeted long-read sequencing (LRS) is expected to comprehensively analyze diverse complex variants in hemophilia A (HA) and hemophilia B (HB) caused by the F8 and F9 genes, respectively. However, its clinical applicability still requires extensive validation.

OBJECTIVES

To evaluate the clinical applicability of targeted LRS-based analysis compared with routine polymerase chain reaction (PCR)-based methods.

METHODS

Gene variants of retrieved subjects were retrospectively and prospectively analyzed. Whole-genome sequencing was performed to further analyze undiagnosed cases. Breakpoints of novel genomic rearrangements were mapped and validated using long-distance PCR and long-range PCR combined with sequencing.

RESULTS

In total, 122 subjects were retrieved. In retrospective analysis of the 90 HA cases, HA-LRS assay showed consistent results in 84 cases compared with routine methods and characterized 6 large deletions with their exact breakpoints confirmed by further validation in 6 cases (routine methods only presented failure in amplifying the involved exons). In prospective analysis of the 21 HA subjects, 20 variants of F8 were identified in 20 cases. For the remaining HA patient, no duplication/deletion or single-nucleotide variant (SNV)/insertion and deletion (InDel) was found, but a potential recombination involving exons 14 and 21 of F8 was observed by LRS. Whole-genome sequencing analysis and further verification defined a 30 478 base pairs (bp) tandem repeat involving exons 14 to 21 of F8. Among the 11 HB patients, HB-LRS analysis detected 11 SNVs/InDels in F9, consistent with routine methods.

CONCLUSION

Targeted LRS-based analysis was efficient and comprehensive in identifying SNVs/InDels and genomic rearrangements of hemophilia genes, especially when we first expanded the panel to include F9. However, further investigation for complex gross rearrangement is still essential.

Rescue immune tolerance induction with a recombinant factor Fc-fused VIII: prospective ReITIrate study of clinical, humoral and cellular immune responses

Background

Immune tolerance induction (ITI) is the gold standard for inhibitor eradication to restore the clinical efficacy of factor replacement therapy in haemophilia. However, as ITI often requires frequent administration over extended periods, it can be considered burdensome for patients and healthcare resources. Therefore, there is a need to optimise ITI treatment, particularly in patients who failed previous ITI attempts.

Objectives

The ReITIrate study aimed to prospectively evaluate rescue ITI with efmoroctocog alfa, an extended half-life recombinant FVIII Fc fusion protein (herein rFVIIIFc), within a limited 60-week timeframe in patients with severe haemophilia A and inhibitors who failed previous ITI attempts.

Design

ReITIrate was a phase IV, open-label, single-arm, interventional, multicentre study.

Methods

Primary endpoint was ITI success (negative titre, <0.6 BU/mL; incremental recovery >66%; elimination half-life ⩾7 hours) within 60 weeks. Exploratory immunophenotype analyses were performed to characterise anti-drug antibodies (ADA) and cellular immune responses.

Results

Nine of 16 enrolled subjects completed the ITI period during ReITIrate, of which one subject attained all 3 ITI success criteria after 46 weeks with no relapse. Two subjects achieved partial success (one subject met 2/3 success criteria; one met all criteria, but not simultaneously, with inhibitor recurrence). One additional subject (ITI failure) achieved negative inhibitor titre. Across these four subjects, median (range) time to negative titre was 19 (11-60) weeks. No new safety concerns were identified. IgG4 was the major contributor to the ADA IgG response. Subjects with partial/complete ITI success had fewer IgG subclasses involved than those who failed/withdrew. Immunophenotyping indicated an increase in regulatory T-cells (CD4+CD25+CD127low), supporting the ability to perform sensitive blood sampling to identify immune tolerance markers.

Conclusion

This study demonstrates that ITI with rFVIIIFc given within a limited timeframe has potential benefit in a difficult-to-treat inhibitor haemophilia population who failed previous ITI attempts.

Trial registration

NCT03103542.

Performance of instrumental activities of daily living in patients with haemophilic arthropathy. A cross-sectional cohort study

BACKGROUND

The development of haemophilic arthropathy causes joint damage that leads to functional impairment that limits the performance of activities in patients with haemophilia. The aim was to identify the best predictive model for performing instrumental activities of daily living in adult patients with haemophilia arthropathy.

METHODS

Cross-sectional cohort study. 102 patients were recruited. The dependent variable was the performance of instrumental activities of daily living (Lawton and Brody scale). The dependence on the performance of activities of daily living was the dependent endpoint (Barthel scale). The secondary variables were joint damage (Hemophilia Joint Health Score), pain intensity, and clinical, anthropometric, and sociodemographic variables.

RESULTS

The degree of dependence, joint damage, pain intensity, and marital status (Cp = 5.60) were the variables that best explain the variability in the performance of instrumental activities of daily living (R2 adj = 0.51). Loss of predictive capacity is acceptable with good mean internal (R2 mean = 0.40) and external (R2-r2 = 0.09) validation. According to the predictive pattern obtained, patients with haemophilia, who were married, without joint pain or damage, and independent in their day-to-day lives, had a score of 7.91 points (95% CI: 7.42; 8.39) in the performance of instrumental activities of daily living.

CONCLUSIONS

The predictive model for the functional capacity of instrumental activities of daily living in haemophilia patients encompasses factors such as level of autonomy, joint impairment, pain severity, and marital status. Notably, despite the presence of joint damage, individuals with haemophilia exhibit a significant level of independence in carrying out both basic daily tasks and instrumental activities of daily living.

INTERNATIONAL REGISTRATION NUMBER

Id NCT04715100.

Real-world effectiveness of eptacog beta in patients with haemophilia and inhibitors: A multi-institutional case series

INTRODUCTION

The management of bleeding events (BEs) in haemophilia A (HA) and B (HB) patients with inhibitors necessitates the use of bypassing agents. The recombinant factor VIIa bypassing agent eptacog beta has demonstrated efficacy at treating BEs and managing perioperative bleeding in adults in phase three clinical studies.

AIM

To provide real-world descriptions of eptacog beta use for BE treatment in patients on emicizumab or eptacog beta prophylaxis.

METHODS

This is a retrospective case series of 14 patients who received eptacog beta at seven haemophilia treatment centres, with HA (n = 11) or HB (n = 3) and inhibitors or anaphylaxis to factor replacement.

RESULTS

Twenty-four spontaneous and traumatic BEs are described (muscle hematomas, joint hemarthroses, port site, and epistaxis) involving 11 subjects. Eptacog beta was effective for acute bleed treatment as both first-line therapy and for treatment of BEs refractory to eptacog alfa in 23/24 events. When eptacog beta was used for prophylaxis, 2/3 patients reported a decreased frequency of breakthrough BEs compared with prophylactic eptacog alfa and one patient experienced a similar frequency of breakthrough BEs compared with prophylactic activated prothrombin complex concentrate. Eptacog beta provided effective bleed control for three subjects who underwent minor surgical procedures. Treatment with eptacog beta was estimated to be 46%-72% more cost-effective than eptacog alfa. No safety concerns or adverse events were reported.

CONCLUSIONS

In this case series, eptacog beta was safe, effective, and economical as first-line therapy, treatment of refractory BEs, management of perioperative bleeding, or prophylaxis in haemophilia patients with inhibitors.

Activated factor X delivered by adeno-associated virus significantly inhibited bleeding and alleviated hemophilic synovitis in hemophilic mice

In hemophilia, deficiency of factor VIII or IX prevents the activation of the common coagulation pathway, and inhibits the conversion of FX to activated FXa, which is required for thrombin generation. We hypothesized that the direct expressed FXa has the potential to activate the common pathway and restore coagulation in hemophilia patients. In this study, the cassettes that expressed FXa, FXaop and FXa-FVII were packaged into an engineered AAV capsid, AAV843, and were delivered into hemophilia A and B mice by intravenous injection. AAV-FXaop could be stably expressed in vivo and showed the best immediate and prolonged hemostatic effects, similar to those of commercial drugs (Xyntha and Benefix). AAV-FXaop also significantly inhibited bleeding in hemophilia A mice with inhibitors. In addition, FXa expression in joints significantly alleviated the occurrence of hemophilic synovitis. AAV-delivered FXa may be a novel target for treating hemophilic and hemophilic synovitis.

Large deletions and small insertions and deletions in the factor VIII gene predict unfavorable immune tolerance induction outcome in people with severe hemophilia A and high-responding inhibitors

INTRODUCTION

Hemophilia A is an inherited bleeding disorder caused by pathogenic variants in the factor VIII gene (F8), which leads to factor VIII (FVIII) deficiency. Immune tolerance induction (ITI) is a therapeutic approach to eradicate alloantibodies (inhibitors) against exogenous FVIII in people with inherited hemophilia A. Few studies have evaluated the role of F8 variants on ITI outcome.

MATERIAL AND METHODS

We included people with severe hemophilia A (FVIII ˂ 1 international units/dL) and high-responding inhibitors (≥ 5 Bethesda units/mL lifelong) who underwent a first course of ITI. Socio-demographic, clinical and laboratory data were collected. ITI outcomes were defined as total, partial successes, and failure. Detection of intron 1 and 22 inversions was performed by polymerase-chain reaction, followed by F8 sequencing.

RESULTS

We included 168 people with inherited hemophilia A and high-responding inhibitors, median age 6 years at ITI start. Intron 22 inversion was the most prevalent variant (53.6 %), followed by nonsense (16.1 %), small insertion/deletion (11.3 %), and large deletion (10.7 %). In comparison with intron 22 inversion, the odds of ITI failure were 15.5 times higher (odds ratio [OR] 15.50; 95 % confidence interval [95 % CI] 4.59-71.30) and 4.25 times higher (95 % CI, 1.53-12.3) among carriers of F8 large deletions and small insertions and deletions, respectively.

CONCLUSION

F8 large deletions and small insertions/deletions predicted ITI failure after a first course of ITI in patients with severe hemophilia A and high-responding inhibitors. This is the first study to show F8 large deletions and small insertions/deletions as predictors of ITI failure.

Real-world use of recombinant porcine sequence factor VIII in the treatment of acquired hemophilia A: EU PASS

Background

Recombinant porcine factor VIII (rpFVIII; susoctocog alfa) is indicated for the treatment of bleeding events (BEs) in adults with acquired hemophilia A (AHA).

Objectives

To assess the safety, utilization, and effectiveness of rpFVIII in clinical practice.

Design

EU post-authorization safety study (PASS) (NCT03199794) was a multicenter, noninterventional, post-authorization safety study conducted in adults with AHA.

Methods

Data were collected retrospectively or prospectively for up to 180 days after the last rpFVIII dose. The primary objective was safety, as assessed by adverse events (AEs), serious AEs (SAEs), and AEs of special interest (AESIs) (e.g. immunogenicity, hypersensitivity reactions, thromboembolic events). Secondary endpoints included immunogenicity, rpFVIII hemostatic effectiveness, and rpFVIII utilization.

Results

Fifty patients were enrolled; 31 completed the study. The median (range) follow-up for patients who completed or discontinued the study was 178 (26-371) days. The median (range) first dose of rpFVIII was 54.0 (11-200) U/kg. Thirty patients reported 46 SAEs; 5 SAEs were considered probably related to rpFVIII, of which 1 was lack of rpFVIII efficacy, and 4 were AESIs: drug resistance due to FVIII inhibition (one patient), antibody test positive for anti-pFVIII inhibitors (one patient), and de novo anti-pFVIII inhibitors (two patients). No hypersensitivity reactions or thromboembolic events were reported. Of the 50 initial BEs, 37 resolved [in a median (interquartile range) of 8.0 (4.0-16.0) days].

Conclusion

Results from this real-world study support the use of rpFVIII for AHA, aligning with findings from the clinical trial of rpFVIII (NCT01178294) in the treatment of BEs in adults with AHA.

Trial registration

EUPAS16055; NCT03199794.

Cost of hemophilia A in Brazil: a microcosting study

BACKGROUND

Patients with Hemophilia are continually monitored at treatment centers to avoid and control bleeding episodes. This study estimated the direct and indirect costs per patient with hemophilia A in Brazil and evaluated the cost variability across different age groups.

METHODS

A prospective observational research was conducted with retrospective data collection of patients assisted at three referral blood centers in Brazil. Time-driven Activity-based Costing method was used to analyze direct costs, while indirect costs were estimated based on interviews with family and caregivers. Cost per patient was analyzed according to age categories, stratified into 3 groups (0-11;12-18 or older than 19 years old). The non-parametric Mann-Whitney test was used to confirm the differences in costs across groups.

RESULTS

Data from 140 hemophilia A patients were analyzed; 53 were 0-11 years, 29 were 12-18 years, and the remaining were older than 19 years. The median cost per patient per year was R$450,831 (IQR R$219,842; R$785,149; $174,566), being possible to confirm age as a cost driver: older patients had higher costs than younger's (p = 0.001; median cost: 0-11 yrs R$299,320; 12-18 yrs R$521,936; ≥19 yrs R$718,969).

CONCLUSION

This study is innovative in providing cost information for hemophilia A using a microcosting technique. The variation in costs across patient age groups can sustain more accurate health policies driven to increase access to cutting-edge technologies and reduce the burden of the disease.

Reduced Volume and Faster Infusion Rate of Activated Prothrombin Complex Concentrate: A Phase 3b/4 Trial in Adults with Hemophilia A with Inhibitors

Background  Activated prothrombin complex concentrate (aPCC) is indicated for bleed treatment and prevention in patients with hemophilia with inhibitors. The safety and tolerability of intravenous aPCC at a reduced volume and faster infusion rates were evaluated. Methods  This multicenter, open-label trial (NCT02764489) enrolled adults with hemophilia A with inhibitors. In part 1, patients were randomized to receive three infusions of aPCC (85 ± 15 U/kg) at 2 U/kg/min (the approved standard rate at the time of the study), in a regular or 50% reduced volume, and were then crossed over to receive three infusions in the alternative volume. In part 2, patients received three sequential infusions of aPCC in a 50% reduced volume at 4 U/kg/min and then at 10 U/kg/min. Primary outcome measures included the incidence of adverse events (AEs), allergic-type hypersensitivity reactions (AHRs), infusion-site reactions (ISRs), and thromboembolic events. Results  Of the 45 patients enrolled, 33 received aPCC in part 1 and 30 in part 2. In part 1, 24.2 and 23.3% of patients with regular and reduced volumes experienced AEs, respectively; 11 AEs in eight patients were treatment related. AHRs and ISRs occurred in four (12.1%) and two (6.1%) patients, respectively. In part 2, 3.3 and 14.3% of patients with infusion rates of 4 and 10 U/kg/min experienced AEs, respectively; only one AE in one patient was treatment related; no AHRs or ISRs were reported. Most AEs were mild/moderate in severity. Overall, no thromboembolic events were reported. Conclusions  aPCC was well tolerated at a reduced volume and faster infusion rates, with safety profiles comparable to the approved regimen.

Impact of Replacement Therapy on Pregnancy Outcomes in Hemophilia Carriers: A Historical Cohort Study in Saudi Arabia

This retrospective cohort study evaluates the safety and efficacy of replacement therapy with regard to pregnancy outcomes in hemophilia carriers. Hemophilia carriers face elevated bleeding risks during pregnancy, necessitating meticulous management, including replacement therapy with clotting factors. This research examines the records of 64 pregnant hemophilia carriers at King Fahad Medical City, Riyadh, from January 2010 to December 2023, analyzing their demographic details, hemophilia type and severity, replacement therapy specifics, and pregnancy outcomes. The study found that 62.5% of the participants had hemophilia A, with 43.8% categorized as severe. Most subjects (87.5%) received recombinant factor VIII at a median dosage of 30 IU/kg weekly. Adverse pregnancy outcomes included gestational hypertension (15.6%), preterm labor (18.8%), and postpartum hemorrhage (12.5%). The cesarean section rate was 28.1%. Neonatal outcomes were generally favorable, with median birth weights at 3100 g and mean Apgar scores of 8.2 and 9.1 at 1 and 5 min, respectively. Logistic regression analysis revealed no significant association between adverse events and therapy type or dosage, though a trend towards significance was noted with once-weekly administration (p = 0.082). The study concludes that replacement therapy is a viable method for managing hemophilia in pregnant carriers, leading to generally favorable maternal and neonatal outcomes. However, it underscores the importance of individualized treatment plans and close monitoring to effectively manage the risks associated with hemophilia during pregnancy.

Emicizumab prophylaxis in people with hemophilia A and inhibitors: a systematic review and meta-analysis

BACKGROUND

Until recently, the treatment of people with hemophilia A and inhibitors (PwHAi) was based on the use of bypassing agents (BPA). However, the advent of emicizumab as prophylaxis has demonstrated promising results.

OBJECTIVES

We aimed to compare the bleeding endpoints between PwHAi on BPA and those on emicizumab prophylaxis.

DESIGN AND SETTING

Systematic review of interventions and meta-analysis conducted at the Universidade Federal de Goiás, Goiânia, Goiás, Brazil.

METHODS

The CENTRAL, MEDLINE, Scopus, and LILACS databases were searched on February 21, 2023. Two authors conducted the literature search, publication selection, and data extraction. The selected publications evaluated the bleeding endpoints between PwHAi on emicizumab prophylaxis and those on BPA prophylaxis. The risk of bias was evaluated according to the Joanna Briggs Institute criteria. A meta-analysis was performed to determine the annualized bleeding rate (ABR) for treated bleeds.

RESULTS

Five publications (56 PwHAi) were selected from the 543 retrieved records. Overall, bleeding endpoints were lower during emicizumab prophylaxis than during BPA prophylaxis. All the publications had at least one risk of bias. The only common parameter for the meta-analysis was the ABR for treated bleeds. During emicizumab prophylaxis, the ABR for treated bleeds was lower than during BPA prophylaxis (standard mean difference: -1.58; 95% confidence interval -2.50, -0.66, P = 0.0008; I2 = 68.4%, P = 0.0031).

CONCLUSION

Emicizumab was superior to BPA in bleeding prophylaxis in PwHAi. However, both the small population size and potential risk of bias should be considered when evaluating these results.

SYSTEMATIC REVIEW REGISTRATION

CRD42021278726, https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=278726.

Primary prophylaxis implementation and long-term joint outcomes in Swedish haemophilia A patients

INTRODUCTION

Primary prophylaxis is the gold standard in severe haemophilia A (SHA) but time to escalate the prophylaxis regimen varies.

AIM

Assess prophylaxis implementation and long-term joint health outcomes in SHA with primary prophylaxis.

METHODS

Adult male patients born after 1980, with SHA on primary prophylaxis, started before the age of 3 years and second joint bleed, and no history of FVIII inhibitors, were enrolled. Repeated joint-health examinations were performed with HJHS or HEAD-US; VERITAS-PRO assessed adherence.

RESULTS

Thirty patients were enrolled with, at inclusion, median age 33.5 years, annualized bleed rate and joint bleed rate 0, and FVIII consumption 4232 IU/kg/year, respectively. The median age was 1.2 years, at prophylaxis start once weekly with a median FVIII dose of 47.7 IU/kg, and 1.7 years, by the time escalation to a final regimen had occurred, with a median infusion frequency of thrice weekly and FVIII dose 41.7 IU/kg, respectively. Older age correlated with later transition to escalated prophylaxis (p < .001). Longer time to escalated prophylaxis correlated to more bleeds (p < .001). Median HJHS increased slowly, reaching 4 at 35-40 years. HJHS at 15-20 years correlated with higher HJHS afterwards. Median total HEAD-US score was 1 and correlated with HJHS (p < .001). Median VERITAS-PRO score was 36, indicating good treatment adherence.

CONCLUSION

Primary prophylaxis is effective but does not completely prevent the gradual development of arthropathy in SHA. Joint assessments with HJHS should start at an early age, as they correlate with arthropathy in later life. Prophylaxis escalation should proceed expeditiously to prevent bleeds.

Dental management of people with complex or rare inherited bleeding disorders

Advances in haematological therapies for people with complex or rare inherited bleeding disorders (IBD) have resulted in them living longer, retaining their natural teeth with greater expectations of function and aesthetics. Dental management strategies need to evolve to meet these challenges. Utilising low level laser diode therapy to reduce pre-operative inflammation to reduce the intraoperative and postoperative burden on haemostasis is described in a case series of 12 patients. For these individuals who previously required further medical management to support haemostasis or experienced such prolonged haemorrhage sufficient to warrant hospital admission, haemostasis was achieved in the dental surgery such that they were able to return home with no further medical intervention or overnight stays. Global inequities in accessing novel treatments for complex or rare IBD necessitates a comprehensive understanding of the local haemostatic agents available to dentists and the most commonly used agents and techniques are described including the use of single tooth anaesthesia (STA). STA is a computerised delivery mechanism that allows routine dental procedures that would previously have required block injections needing factor replacement therapy to be undertaken safely and effectively with no additional haemostatic intervention. The challenges of inhibitors in oral surgery are explained and discussed although more research and evidence is required to establish new treatment protocols. The importance of establishing good dental health in the quality of life of people with complex or rare IBD is highlighted with respect to the dental specific impact that more novel therapies may have on people with IBD.

Identification of the Efficient Enhancer Elements in FVIII-Padua for Gene Therapy Study of Hemophilia A

Hemophilia A (HA) is a common X-linked recessive hereditary bleeding disorder. Coagulation factor VIII (FVIII) is insufficient in patients with HA due to the mutations in the F8 gene. The restoration of plasma levels of FVIII via both recombinant B-domain-deleted FVIII (BDD-FVIII) and B-domain-deleted F8 (BDDF8) transgenes was proven to be helpful. FVIII-Padua is a 23.4 kb tandem repeat mutation in the F8 associated with a high F8 gene expression and thrombogenesis. Here we screened a core enhancer element in FVIII-Padua for improving the F8 expression. In detail, we identified a 400 bp efficient enhancer element, C400, in FVIII-Padua for the first time. The core enhancer C400 extensively improved the transcription of BDDF8 driven by human elongation factor-1 alpha in HepG2, HeLa, HEK-293T and induced pluripotent stem cells (iPSCs) with different genetic backgrounds, as well as iPSCs-derived endothelial progenitor cells (iEPCs) and iPSCs-derived mesenchymal stem cells (iMSCs). The expression of FVIII protein was increased by C400, especially in iEPCs. Our research provides a novel molecular target to enhance expression of FVIII protein, which has scientific value and application prospects in both viral and nonviral HA gene therapy strategies.

Loss of factor VIII in zebrafish rebalances antithrombin deficiency but has a limited bleeding diathesis

Deficiencies in coagulation factor VIII (FVIII, F8) result in the bleeding disorder hemophilia A. An emerging novel therapeutic strategy for bleeding disorders is to enhance hemostasis by limiting natural anticoagulants, such as antithrombin (AT3). To study pro/anticoagulant hemostatic balance in an in vivo model, we used genome editing to create null alleles for f8 and von Willebrand factor (vwf) in zebrafish, a model organism with a high degree of homology to the mammalian hemostatic system and unique attributes, including external development and optical transparency. f8 homozygous mutant larvae surprisingly formed normal thrombi when subjected to laser-mediated endothelial injury, had no overt signs of hemorrhage, but had a modest increase in mortality. We have previously shown that at3 -/- larvae develop disseminated intravascular coagulation (DIC), with spontaneous thrombosis and fibrinogen consumption, resulting in bleeding phenotype marked by secondary lack of induced thrombus formation upon endothelial injury. We found that with loss of FVIII (f8 -/-;at3 -/-), larvae no longer developed spontaneous fibrin thrombi and did produce clots in response to endothelial injury. However, homozygous loss of zebrafish Vwf failed to rescue the at3 DIC phenotype. These studies demonstrate an altered balance of natural anticoagulants that mitigates FVIII deficiency in zebrafish, similar to human clinical pipeline products. The data also suggest that zebrafish FVIII might circulate independently of Vwf. Further study of this unique balance could provide new insights for management of hemophilia A and von Willebrand disease.

Anti-Thrombin IgA in a Patient with Multiple Myeloma Leading to In Vitro Interference in Multiple Coagulation Tests and Confounding Diagnosis

BACKGROUND

 We report the case of a 59-year-old multiple myeloma patient in whom an anti-human thrombin IgA antibody led to prolonged in vitro coagulation times, suggesting inhibitors to all intrinsic coagulation factors in the absence of spontaneous bleeding.

METHODS

 Routine and extensive special coagulation tests, in vivo bleeding time, and specific antibody testing were performed.

RESULTS

 Although the patient did not suffer from spontaneous bleeding and had a normal in vivo bleeding time, the anti-human thrombin IgA autoantibody affected all coagulation assays involving human thrombin in vitro, mimicking inhibitors to intrinsic coagulation factors. As the IgA paraprotein and the IgA antibody virtually disappeared after autologous stem cell transplantation, the coagulation tests also largely normalized.

CONCLUSION

 Antibodies to human thrombin may interfere with all coagulation assays involving thrombin, imitating a severe coagulopathy. However, in vivo they do not necessarily lead to strongly increased bleeding tendency. Complex and ambiguous coagulation abnormalities should be evaluated and treated in an interdisciplinary setting, including a highly specialized coagulation laboratory, from the beginning.

The current challenges faced by people with hemophilia B

Hemophilia B (HB) is a rare, hereditary disease caused by a defect in the gene encoding factor IX (FIX) and leads to varying degrees of coagulation deficiency. The prevailing treatment for people with HB (PWHB) is FIX replacement product. The advent of recombinant coagulation products ushered in a new era of safety, efficacy, and improved availability compared with plasma-derived products. For people with severe HB, lifelong prophylaxis with a FIX replacement product is standard of care. Development of extended half-life FIX replacement products has allowed for advancements in the care of these PWHB. Nonetheless, lifelong need for periodic dosing and complex surveillance protocols pose substantive challenges in terms of access, adherence, and healthcare resource utilization. Further, some PWHB on prophylactic regimens continue to experience breakthrough bleeds and joint damage, and subpopulations of PWHB, including women, those with mild-to-moderate HB, and those with inhibitors to FIX, experience additional unique difficulties. This review summarizes the current challenges faced by PWHB, including the unique subpopulations; identifying the need for improved awareness, personalized care strategies, and new therapeutic options for severe HB, which may provide future solutions for some of the remaining unmet needs of PWHB.

Arthropathy on X-rays in 363 persons with hemophilia: long-term development, and impact of birth cohort and inhibitor status

Background

Arthropathy following repeated bleeding is common in persons with hemophilia. Since the introduction of prophylaxis, treatment has intensified and joint health has improved. However, data on the long-term development of arthropathy are still scant.

Objectives

To evaluate long-term arthropathy development since the introduction of prophylaxis according to birth cohort, hemophilia severity, and inhibitor status.

Methods

This single-center historic cohort study included persons with severe and moderate hemophilia A and hemophilia B born between 1935 and 2005. Arthropathy on X-rays was evaluated using the Pettersson score. Patient and joint characteristics were studied per birth cohort (<1970, 1970-1980, 1981-1990, and >1990) and compared according to hemophilia severity. The distribution of affected joints and cumulative incidence of arthropathy were analyzed. The association of Pettersson score with birth cohort and inhibitor characteristics was explored using multivariable regression analyses adjusted for age at evaluation.

Results

In total, 1064 X-rays of 363 patients were analyzed. Of persons with severe hemophilia (n = 317, 87.3%), 244 (77.0%) developed arthropathy. Prophylaxis was started at younger ages over time, from a median of 18 to 2.1 years, and concomitantly, arthropathy decreased in consecutive birth cohorts. Ankles were most commonly affected in 188 of 258 (72.9%) patients. Persons with moderate hemophilia (n = 46, 12.7%) had a lower risk of arthropathy (27/46 [58.7%]), but a reduction over time was less pronounced. In the multivariable analyses, birth cohort and age at evaluation were predictors for the development of arthropathy, while inhibitor status showed no association.

Conclusion

The development and severity of arthropathy have decreased over the past decades. However, patients have remained at risk for developing arthropathy, especially in their ankles.

A mechanistic marker-based screening tool to predict clinical immunogenicity of biologics

BACKGROUND

The efficacy and safety of therapeutic proteins are undermined by immunogenicity driven by anti-drug antibodies. Immunogenicity risk assessment is critically necessary during drug development, but current methods lack predictive power and mechanistic insight into antigen uptake and processing leading to immune response. A key mechanistic step in T-cell-dependent immune responses is the migration of mature dendritic cells to T-cell areas of lymphoid compartments, and this phenomenon is most pronounced in the immune response toward subcutaneously delivered proteins.

METHODS

The migratory potential of monocyte-derived dendritic cells is proposed to be a mechanistic marker for immunogenicity screening. Following exposure to therapeutic protein in vitro, dendritic cells are analyzed for changes in activation markers (CD40 and IL-12) in combination with levels of the chemokine receptor CXCR4 to represent migratory potential. Then a transwell assay captures the intensity of dendritic cell migration in the presence of a gradient of therapeutic protein and chemokine ligands.

RESULTS

Here, we show that an increased ability of the therapeutic protein to induce dendritic cell migration along a gradient of chemokine CCL21 and CXCL12 predicts higher immunogenic potential. Expression of the chemokine receptor CXCR4 on human monocyte-derived dendritic cells, in combination with activation markers CD40 and IL-12, strongly correlates with clinical anti-drug antibody incidence.

CONCLUSIONS

Mechanistic understanding of processes driving immunogenicity led to the development of a predictive tool for immunogenicity risk assessment of therapeutic proteins. These predictive markers could be adapted for immunogenicity screening of other biological modalities.

Functional determination of emicizumab in presence of factor VIII activity

BACKGROUND

Accurate measurement of emicizumab in the presence of factor (F) VIII is required in patients with severe hemophilia A treated with emicizumab, as well as additional need for FVIII substitution or emicizumab prophylaxis in patients with acquired or moderate to mild hemophilia A. However, the presence of FVIII potentially biases the results.

OBJECTIVES

To assess the impact of plasma FVIII activity on determined emicizumab levels and evaluate different strategies for correction for or preanalytical inhibition of FVIII.

METHODS

Evaluated strategies comprised of the following: (1) calculation of actual emicizumab plasma levels based on measured FVIII activities and FVIII-affected emicizumab values, (2) preanalytical heat treatment (56 °C for 40 minutes), and (3) neutralization of FVIII activity using FVIII inhibitors. Emicizumab levels and FVIII activities were measured using a modified FVIII one-stage clotting assay and a chromogenic FVIII assay based on bovine factors, respectively.

RESULTS

Spiking experiments revealed a consistent linear association between FVIII activities and determined (FVIII-affected) emicizumab results at different emicizumab input levels (∼0.12 μg/mL per IU/dL of FVIII). This principally allowed for mathematical correction of measured emicizumab levels in the presence of FVIII. While a 40% to 50% activity loss of intrinsic plasma emicizumab through heat treatment was observed in patient samples, emicizumab spiked into FVIII-deficient plasma was not or only marginally affected. Application of inhibitor-based FVIII neutralization led to good agreement of results when compared with direct quantification of emicizumab by liquid chromatography-tandem mass spectrometry.

CONCLUSION

Inhibitor-based FVIII neutralization appears to be a feasible strategy for accurate measurement of plasma emicizumab levels in the presence of FVIII activity.

Altered frequency of FOXP3+ regulatory T cells is associated with development of inhibitors in patients with severe hemophilia A

INTRODUCTION

The development of anti-factor VIII (FVIII) antibodies or "inhibitors" is a major complication following FVIII replacement therapy in patients with severe hemophilia A (HA), rendering the treatment inefficient. Data on the role of regulatory T cells (Tregs) in inhibitor formation in these patients are rare. Herein, we aimed to investigate whether a difference in the FOXP3+ Tregs is linked to the formation of the inhibitors in severe HA patients.

METHODS

In this cross-sectional study, 32 patients with severe HA (8 patients with inhibitors and 24 without inhibitors) and 24 healthy controls were enrolled. The frequency of FOXP3+ Tregs was determined using multicolor flow cytometry method.

RESULTS

Our results showed that the median level of CD4+ CD25+ FOXP3+ Tregs did not significantly differ between HA patients and healthy controls and between HA patients with and without inhibitors (P > 0.05). However, patients with inhibitors had significantly lower amounts of CD4+ CD25- FOXP3+ Tregs compared to those without inhibitors as well as healthy controls (*P = 0.012 and *P = 0.004, respectively). The frequency of CD4+ CD25+ T cells was significantly higher in HA patients who developed inhibitors compared to the inhibitor-negative ones whereas they were lower in inhibitor-negative patients compared to the healthy controls (*P = 0.013 and *P = *0.029, respectively). The percentages of CD4+ CD25+ T cells were positively correlated with the levels of inhibitors in HA patients (r = 0.45, *P = 0.021).

CONCLUSION

Our data demonstrated for the first time that the CD4+ CD25- FOXP3+ Tregs might be implicated in the prevention of inhibitor formation in severe HA patients.

Real-world data on the use of emicizumab in patients with haemophilia A with and without inhibitors in Singapore

Introduction

Emicizumab is a bispecific monoclonal antibody that mimics the function of factor VIII by binding to factor IXa and factor X to achieve haemostasis in haemophilia A. The long half-life and subcutaneous mode of administration makes emicizumab a compelling treatment option for bleeding prophylaxis. There is still limited real-world data on its use and management considerations, especially during surgical procedures. The objective of the study is to describe the real-world experience of emicizumab in a cohort of adult and paediatric haemophilia A patients in Singapore, including its use in the periprocedural setting.

Method

This was an observational study conducted at the 2 main haemophilia treatment centres in Singapore. All haemophilia A patients who commenced treatment with emicizumab before 1 July 2022 were recruited.

Results

A total of 18 patients with haemophilia A were included in this study. Ten (55.6%) patients had active inhibitors. The median annual bleeding rate for all patients before emicizumab use was 4.5 events (interquartile range [IQR] 2.8-8.3) compared with 0 events (IQR 0-0) after emicizumab was commenced (P=0). There were no adverse events of venous or arterial thrombosis, thrombotic microangiopathy, or death. A total of 6 procedures in 5 patients were performed during the study period with no major bleeding complications.

Conclusion

Emicizumab effectively protects against bleeding in haemophilia A patients with and without inhibitors, including in children less than 12 years old. More studies are required to address clinical nuances, such as periprocedural management and the role of immune tolerance in patients with inhibitors on emicizumab.

Awareness of individual goals, preferences, and priorities of persons with severe congenital haemophilia A for a tailored shared decision-making approach to liver-directed gene therapy. A practical guideline

In clinical medicine, shared decision making (SDM) is a well-recognized strategy to enhance engagement of both patients and clinicians in medical decisions. The success of liver-directed gene therapy (GT) to transform severe congenital haemophilia A (HA) from an incurable to a curable disease has launched a shift beyond current standards of treatment. However, GT acceptance remains low in the community of HA persons. We argue for both persons with haemophilia (PWH) and specialists in HA care including clinicians, as needing SDM-oriented educational programs devoted to GT. Here, we provide an ad hoc outline to implement education to SDM and tailor clinician information on GT to individual PWHs. Based on routine key components of SDM: patient priorities; recommendations based on individual risk reduction; adverse effects; drug-drug interactions; alternatives to GT; and ongoing re-assessment of the objectives as risk factors (and individual priorities) change, this approach is finalized to exploit efficacious communication.

Real-world data in patients with congenital hemophilia and inhibitors: final data from the FEIBA Global Outcome (FEIBA GO) study

Background

The bypassing agent, activated prothrombin complex concentrate [aPCC, FEIBA (factor VIII inhibitor bypass activity); Baxalta US Inc, a Takeda company, Lexington, MA, USA], is indicated for the treatment of bleeding episodes, perioperative management, and routine prophylaxis in patients with hemophilia A or B with inhibitors. In certain countries, aPCC is also indicated for the treatment of bleeding episodes and perioperative management in patients with acquired hemophilia A.

Objectives

To describe long-term, real-world effectiveness, safety, and quality-of-life outcomes for patients with congenital hemophilia A or B and high-responding inhibitors receiving aPCC treatment in routine clinical practice.

Design

FEIBA Global Outcome (FEIBA GO; EUPAS6691) was a prospective, observational study.

Methods

Investigators determined the treatment regimen and clinical monitoring frequency. The planned patient observation period was 4 years. Data are from the safety analysis set (patients who received ⩾1 aPCC infusion).

Results

Overall, 50 patients received either aPCC prophylaxis (n = 37) or on-demand therapy (n = 13) at screening [hemophilia A, n = 49; hemophilia B, n = 1; median (range) age, 16.5 [2-71] years). Mean ± standard deviation overall annualized bleeding rate and annualized joint bleeding rate for patients receiving prophylaxis were 6.82 ± 11.52 and 3.77 ± 5.71, respectively, and for patients receiving on-demand therapy were 10.94 ± 11.27 and 6.94 ± 7.39, respectively. Overall, 177 and 31 adverse events (AEs) were reported in 28 of 40 and 10 of 13 patients receiving prophylaxis or on-demand therapy, respectively. Two serious AEs were considered possibly related to aPCC: acute myocardial infarction due to coronary artery embolism in one patient receiving prophylaxis. No thrombotic microangiopathy was reported. No AEs resulted in death.

Conclusion

This study demonstrated the long-term, real-world effectiveness and consistent safety profile of aPCC as on-demand therapy and prophylactic treatment in patients with hemophilia and high-responding inhibitors.

Trial registry

FEIBA Global Outcome Study; EUPAS6691 https://www.encepp.eu/encepp/viewResource.htm?id=32774.

Bleeding events in people with congenital haemophilia A without factor VIII inhibitors receiving prophylactic factor VIII treatment: A systematic literature review

BACKGROUND

Evidence on bleeding rates in people with congenital haemophilia A (PwcHA) without inhibitors on factor VIII (FVIII) replacement products is inconsistent.

AIM

This systematic literature review assessed bleeding outcomes in PwcHA using FVIII-containing products as prophylactic treatment.

METHODS

A search was conducted using the bibliographic databases Medline, Embase and Cochrane Central Register of Controlled Trials on the Ovid platform. The search involved a bibliographic review of clinical trial studies, routine clinical care studies and registries and a search of ClinicalTrials.gov, EU Clinical Trials Register and conference abstracts.

RESULTS

The search yielded 5548 citations. A total of 58 publications were included for analysis. In 48 interventional studies, the pooled estimated mean (95% confidence interval [CI]) annualized bleeding rate (ABR), annualized joint bleeding rate (AJBR) and proportion of participants with zero bleeding events were 3.4 (3.0-3.7), 2.0 (1.6-2.5), and 38.5% (33.1-43.9), respectively. In 10 observational studies, the pooled estimated mean (95% CI) ABR, AJBR and proportion of participants with zero bleeding events were 4.8 (4.0-5.5), 2.6 (2.1-3.2), and 21.8% (19.9-47.5), respectively. A large variation in mean effect size for ABR, AJBR and zero bleeding event data across cohorts and cohort types was observed. Funnel plots indicated potential reporting bias for publications incorporating ABR and AJBR data across both interventional and observational studies.

CONCLUSION

This meta-analysis shows that PwcHA without inhibitors still have bleeds despite FVIII prophylaxis. Improved standardization on capturing and reporting bleeding outcomes is needed so that effective comparisons between treatments can be made.

Efficacy and safety of fitusiran prophylaxis in people with haemophilia A or haemophilia B with inhibitors (ATLAS-INH): a multicentre, open-label, randomised phase 3 trial

BACKGROUND

Fitusiran, a subcutaneous investigational small interfering RNA therapeutic, targets antithrombin to rebalance haemostasis in people with haemophilia A or haemophilia B, irrespective of inhibitor status. We evaluated the efficacy and safety of fitusiran prophylaxis in people with haemophilia A or haemophilia B with inhibitors.

METHODS

This multicentre, randomised, open-label phase 3 study was done at 26 sites (primarily secondary or tertiary centres) in 12 countries. Men, boys, and young adults aged 12 years or older with severe haemophilia A or haemophilia B with inhibitors previously treated with on-demand bypassing agents were randomly assigned (2:1) to receive once-a-month 80 mg subcutaneous fitusiran prophylaxis (fitusiran prophylaxis group) or to continue with bypassing agents on-demand (bypassing agents on-demand group) for 9 months. The primary endpoint was mean annualised bleeding rate during the efficacy period in the intention-to-treat population estimated by negative binomial model. Safety was assessed as a secondary endpoint in the safety population. This trial is complete and is registered with ClinicalTrials.gov, NCT03417102.

FINDINGS

Between Feb 14, 2018, and June 23, 2021, 85 participants were screened for inclusion, of whom 57 (67%; 57 [100%] men; median age 27·0 years [IQR 19·5-33·5]) were randomly assigned: 19 (33%) participants to the bypassing agent on-demand group and 38 (67%) participants to the fitusiran prophylaxis. Negative binomial model-based mean annualised bleeding rate was significantly lower in the fitusiran prophylaxis group (1·7 [95% CI 1·0-2·7]) than in the bypassing agents on-demand group (18·1 [10·6-30·8]), corresponding to a 90·8% (95% CI 80·8-95·6) reduction in annualised bleeding rate in favour of fitusiran prophylaxis (p<0·0001). 25 (66%) participants had zero treated bleeds in the fitusiran prophylaxis group versus one (5%) in the bypassing agents on-demand group. The most frequent treatment-emergent adverse event in the fitusiran prophylaxis group was increased alanine aminotransferase in 13 (32%) of 41 participants in the safety population; there were no increased alanine aminotransferase treatment-emergent adverse events in the bypassing agents on-demand group. Suspected or confirmed thromboembolic events were reported in two (5%) participants in the fitusiran prophylaxis group. No deaths were reported.

INTERPRETATION

Subcutaneous fitusiran prophylaxis resulted in statistically significant reductions in annualised bleeding rate in participants with haemophilia A or haemophilia B with inhibitors, with two-thirds of participants having zero bleeds. Fitusiran prophylaxis might show haemostatic efficacy in participants with haemophilia A or haemophilia B with inhibitors; therefore, the therapeutic might have the potential to improve the management of people with haemophilia.

FUNDING

Sanofi.

Economic Evaluation of Immune Tolerance Induction in Children With Severe Hemophilia A and High-Responding Inhibitors: A Cost-Effectiveness Analysis of Prophylaxis With Emicizumab

OBJECTIVE

This study aimed to measure the cost-effectiveness of prophylaxis with emicizumab in PsHAhri on ITI in Brazil.

METHODS

A cost-effectiveness modeling analysis was used to estimate the costs per PsHAhri on ITI and the number of prevented bleedings from undertaking one intervention (prophylaxis with BpA) over another (prophylaxis with emicizumab), based on the Brazilian Ministry of Health perspective. Costs of ITI with recombinant FVIII, prophylaxis with BpA or emicizumab, and treated bleeding episodes with BpA costs were evaluated for PsHAhri who had ITI success or failure. This study was conducted with the perspective of the Brazilian Ministry of Health (payer).

RESULTS

During ITI, prophylaxis with BpA cost US $924 666/PsHAhri/ITI, whereas prophylaxis with emicizumab cost US $488 785/PsHAhri/ITI. During ITI, there was an average of 9.32 bleeding episodes/PsHAhri/ITI when BpA were used as prophylaxis and 0.67 bleeding/PsHAhri/ITI when emicizumab was used. By univariate deterministic sensitivity analysis, emicizumab remained dominant whichever variable was modified.

CONCLUSION

In this study, prophylaxis with emicizumab during ITI is a dominant option compared with prophylaxis with BpA during ITI.

Progress, and prospects in the therapeutic armamentarium of persons with congenital hemophilia. Defining the place for liver-directed gene therapy

In persons with congenital severe hemophilia A (HA) living in high-income countries, twice weekly intravenous infusions of extended half-life (EHL) factor VIII (FVIII) products, or weekly/biweekly/monthly subcutaneous injections of emicizumab are the gold standard home treatments to grant days without hurdles and limitations. Once weekly/twice monthly infusions of EHL Factor IX (FIX) products achieve the same target in severe hemophilia B (HB). Gene therapy, which is likely to be licensed for clinical use within 1-2 years, embodies a shift beyond these standards. At an individual patient level, a single functional gene transfer leads to a > 10-yr almost full correction of the hemostatic defect in HB and to a sustained (3-6-yrs) expression of FVIII sufficient to discontinue exogenous clotting factor administrations. At the doses employed, the limited liver toxicity of systemically infused recombinant adeno-associated virus (rAAV) vectors is documented by long-term (12-15 yrs) follow-ups, and pre-existing high-titer neutralizing antibodies to the AAV5 vector are no longer an exclusion criterion for effective transgene expression with this vector. A safe durable treatment that converts a challenging illness to a phenotypically curable disease, allows persons to feel virtually free from the fears and the obligations of hemophilia for years/decades. Along with patient organizations and health care professionals, communicating to government authorities and reimbursement agencies the liberating potential of this substantial innovation, and disseminating across the Centers updated information on benefits and risks of this strategy, will align expectations of different stakeholders and establish the notion of a potentially lifelong cure of hemophilia.

An updated interactive database for 1692 genetic variants in coagulation factor IX provides detailed insights into hemophilia B

BACKGROUND

Genetic variants in coagulation factor IX (FIX) are associated with hemophilia B, a rare bleeding disease. F9 variants are widespread across the gene and were summarized in our FIX variant database introduced in 2013.

OBJECTIVES

We aimed to rationalize the molecular basis for 598 new F9 variants and 1645 new clinical cases, totaling 1692 F9 variants and 5358 related patient cases.

METHODS

New F9 variants were identified from publications and online resources, and compiled into a MySQL database for comparison with the human FIXa protein structure.

RESULTS

The new total of 1692 F9 variants correspond to 406 (88%) of the 461 FIX residues and now include 70 additional residues. They comprise 945 unique point variants, 281 deletions, 352 polymorphisms, 63 insertions, and 51 others. Most FIX variants were point variants, although their proportion (56%) has reduced compared to 2013 (73%); at the same time, the proportion of polymorphisms has increased from 5% to 21%. The 764 unique mild severity variants in the mature protein with known phenotypes include 74 (9.7%) quantitative type I variants and 116 (15.2%) predominantly qualitative type II variants. The remaining 574 variants types are unspecified. Inhibitors are associated with 152 hemophilia B cases out of 5358 patients (2.8%), an increase of 93 from the previous database.

CONCLUSION

The even distribution of the F9 variants revealed few mutational hotspots, and most variants were associated with small perturbations in the FIX protein structure. The updated database will assist clinicians and researchers in assessing treatments for patients with hemophilia B.

Total knee arthroplasty and femoral osteotomy with a patient-specific cutting guide to treat haemophilic arthritis with severe extra-articular deformity: A case report and review of literatures

Background

Total knee arthroplasty (TKA) is recommended for haemophilic patients with end-stage arthritis. TKA combined with a one-stage extraarticular osteotomy is uncommon in the treatment of haemophilic arthritis (HA) with severe extra-articular deformities (EADs) and a history of inhibitors under the guidance of a patient-specific cutting guide (PSI).

Case presentation

We reported a 20-year-old male patient with severe haemophilia, limited knee functionality, a 30° sagittal deformity on the femoral side and a history of inhibitors. We adopted the Van Creveld protocol to decrease the inhibitors. TKA and extra-articular osteotomy (EAO) were performed simultaneously and sequentially under the guidance of PSI. An appropriate central alignment of the lower limb was restored by using cement prostheses with antibiotics and femur shaft locking compression plates. The last follow-up showed that the knee function was good, the VAS score was 0, the WOMAC score was 18 and the ROM was 0°-95°.

Conclision

Regular haematology management can reduce the perioperative bleeding risk in haemophilic patients treated with inhibitors. PSI plays an important role in guiding the TKA and EAO of end-stage HA patients with severe EAD.

Factor IX inhibitors in haemophilia B: A report of National Haemophilia Registry in China

INTRODUCTION

The development of inhibitors against factor FIX (FIX) is the most serious complication of FIX replacement therapy in haemophilia B (HB) patients. Currently, only few cohorts of HB inhibitor patients have been reported worldwide.

AIM

This Chinese nationwide study of HB inhibitor patients explored their risk factors for FIX inhibitor development and experience on their management.

METHODS

We retrospectively analysed patient characteristics, F9 genotypes, treatment strategies and outcomes of HB inhibitor patients registered to the Chinese National Registry and Patient Organization Registry.

RESULTS

Forty-four unique HB inhibitor patients were identified in 4485 unique HB patients registered by year 2021 to the two Registries. Inhibitor diagnosis were usually delayed and the low prevalence (.98%) may suggest some inhibitor patients were not identified. Their median age at inhibitor diagnosis was 7.5 (IQR, 3.0-14.8) years. Most patients (95.5%) had high-titre inhibitors. Allergic/Anaphylactic reactions occurred in 59.1% patients. Large deletions and nonsense mutations were the most common F9 mutation types in our FIX inhibitor patients. Patients with large F9 gene deletions were more likely to develop inhibitors (p = .0002), while those with missense mutations had a low risk (p < .0001). Thirteen (29.5%) patients received immune tolerance induction (ITI) therapy using low-dose prothrombin complex concentrate regimens. Twelve completed ITI with three (25.0%) achieving success. Nephrotic syndrome developed in two (16.7%) patients during ITI.

CONCLUSION

This study reports the largest Chinese cohort of HB inhibitor patients. Large deletions were most significantly associated with inhibitor development. Low-dose ITI might be feasible for FIX inhibitor eradication.

FVIII inhibitor surveillance in children with hemophilia A in Indonesia: a report from the Indonesian Pediatric Hematology-Oncology Working Group

Background

Factor VIII (FVIII) inhibitor diagnosis and surveillance in Indonesia are challenging owing to geographic conditions and the lack of laboratory facilities nationwide for inhibitor assays. This study aimed to determine the prevalence of FVIII inhibitors in children diagnosed with hemophilia A (HA) in Indonesia.

Methods

A cross-sectional study was conducted in 12 hospitals in eight provinces of Indonesia between 2020 and 2021. Factor VIII inhibitor screening was performed in a central hemostasis laboratory for all children with HA (≤18 yr) who had received a minimum of 10 exposure days to clotting factor concentrates. The FVIII inhibitor titer was determined using the Bethesda assay.

Results

Children (388) were enrolled in this study, including 219 (56.4%), 131 (33.8%), and 38 (9.4%) with severe, moderate, and mild HA, respectively. The prevalence of children who developed FVIII inhibitors was 37 out of 388 (9.6%). Factor VIII inhibitors were found in 25/219 (11.4%) severe, 11/131 (8.3%) moderate, and 1/38 (2.6%) children with mild HA. Thirteen children had low-titer inhibitors and 24 had high-titer inhibitors, with a median of 9.44 (1.48‒412.0) Bethesda Units. Among 13 children with low-titer inhibitors, eight underwent a confirmation test, of which five tested negative and were classified as transient. A significant difference in annual joint bleeding rate was found between patients with low and high inhibitor titers and those without inhibitors (P＜0.001).

Conclusion

Factor VIII inhibitor prevalence in Indonesia was relatively low. However, the risk factors that may contribute to FVIII inhibitor development among Indonesian patients require further study.

Gene therapy for hemophilia: looking beyond factor expression

Hemophilia A (factor VIII [FVIII] deficiency) and hemophilia B (factor IX [FIX] deficiency) are the X-linked recessive bleeding disorders that clinically manifest with recurrent bleeding, predominantly into muscles and joints. In its severe presentation, when factor activity is less than 1% of normal, hemophilia presents with spontaneous musculoskeletal bleeds and may progress to debilitating chronic arthropathy. Management of hemophilia has changed profoundly in the past decades. From on-demand to prophylactic factor concentrate replacement, the treatment goal shifted from controlling bleeds to preventing bleeds and improving quality of life. In this new scenario, gene therapy has arisen as a paradigm-changing therapeutic option, a one-time treatment with the potential to achieve sustained coagulation FVIII or FIX expression even within the normal range. This review discusses the critical impact of adeno-associated virus (AAV) gene transfer in hemophilia care, including the recent clinical outcomes, changes in disease perceptions, and its treatment burden. We also discuss the challenging scenario of the AAV-directed immune response in the clinical setting and potential strategies to improve the long-lasting efficacy of hemophilia gene therapy efficacy.

Hemophilic Arthropathy: Barriers to Early Diagnosis and Management

Hemophilia is a congenital coagulopathy characterized by a deficiency of one of the clotting factors. It is characterized by the development of hematomas and hemarthrosis, either spontaneously or after minor trauma. The recurrence of hemarthroses leads to progressive and degenerative joint damage from childhood (hemophilic arthropathy). This arthropathy is characterized by disabling physical effects that limit the functionality and quality of life of these patients. Medical progress achieved over the last decade in the drug treatment of hemophilia has improved the medium and long-term prospects of patients with more effective and long-lasting drugs. The universal use of safer, more effective and prolonged prophylactic treatments may promote the prevention of bleeding, and also therefore, of the development of hemarthrosis and joint damage. A number of imaging instruments have been developed for the assessment of hemarthrosis and hemophilic arthropathy, using ultrasound, magnetic resonance imaging and simple radiology. Different physical examination scores and questionnaires allow the assessment of joint health, self-perceived activity and functionality of patients with hemophilia. The approach to these patients should be interdisciplinary. Assessment of the processes that affect pain in these patients and the development of pain education models should be implemented. Expert advice and information to patients with hemophilia should be based on individual functional prevention diagnoses, advice on available therapies and sports practice, as well as health recommendations.

Factor IX antibodies and tolerance in hemophilia B in the Nordic countries - The impact of F9 variants and complications

INTRODUCTION

The development of inhibitory antibodies (inhibitors) in persons with hemophilia B (PwHB) causes significant morbidity. Data on the impact of the F9 variant and immune tolerance induction (ITI) outcome are limited. The aim of this study was to investigate the presence of neutralizing and non-neutralizing antibodies (NNA) in severe hemophilia B (HB) and to evaluate ITI outcome and complications in relation to the pathogenic F9 variant.

MATERIALS AND METHODS

Persons with severe HB in the Nordic countries were enrolled and information on F9 variants, inhibitors, ITI and complications were collected. Analyses of anti-FIX antibodies with a fluorescence-immunoassay (xFLI) and an ELISA method were conducted.

RESULTS

Seventy-nine PwHB were enrolled. Null variants were seen in 33 (42 %) PwHB and 12 (15 %) had a current or former inhibitor. Eleven (92 %) of the inhibitor patients had experienced allergic manifestations and three (25 %) nephrotic syndrome. Of 10 PwHB with at least one ITI attempt, eight (80 %) were considered tolerant at enrolment. Immunosuppression was included in seven of eight successful or partially successful attempts. Five PwHB had at least one ITI failure before a successful or partially successful ITI. No NNA could be identified.

CONCLUSION

A high proportion of severe F9 gene defects among persons with severe HB in the Nordic countries may explain the observed relatively high prevalence of inhibitors. ITI success was independent of the F9 variant and attained despite allergic manifestations and previous ITI failures. Inclusion of immunosuppression tentatively enhances the chances of ITI success. No NNA were observed.

Recent advances in therapeutic options for rare hemostatic disorders: selected poster extracts of recent research in hemophilia A, congenital hemophilia with inhibitors, von Willebrand disease, and thrombotic thrombocytopenic purpura presented at the 29th congress of the International Society on Thrombosis and Haemostasis (ISTH 2021, Jul 17-21; virtual congress)

Hemophilia, von Willebrand disease (VWD), and thrombotic thrombocytopenic purpura (TTP) are rare diseases affecting normal hemostasis. Although they differ in their pathogenesis and clinical manifestation, if left undiagnosed and untreated, all these conditions can result in severe long-term consequences and can be potentially life-threatening. This article summarizes a poster series funded by Takeda and presented virtually at the 29th annual congress of the International Society on Thrombosis and Haemostasis (ISTH) in 2021: Data from real-world evidence highlight the importance of joint health and personalized prophylaxis to prevent bleeding for patients with hemophilia, the need to further raise disease awareness in support of timely diagnosis and access to treatment in general practice settings for patients with VWD, and describe the clinical burden for patients with TTP and the importance to advance treatment options for these patients.

Immune Tolerance Induction (ITI) with a pdFVIII/VWF Concentrate (octanate) in 100 Patients in the Observational ITI (ObsITI) Study

Background  Immune tolerance induction (ITI) with repeated factor VIII (FVIII) administration is the only strategy proven to eradicate inhibitors. The observational ITI study is evaluating ITI with a range of FVIII products.

Methods  This subgroup analysis reports prospective interim data for patients treated with a plasma-derived, von Willebrand factor-stabilized FVIII concentrate (pdFVIII/VWF, octanate). Complete success (CS) of ITI required achievement of three criteria: inhibitor titer < 0.6 BU/mL; FVIII recovery ≥ 66%; FVIII half-life ≥6 hours. Partial success (PS) required achievement of two criteria and partial response (PR) one. ITI success was defined as CS or PS. Data were analyzed for patients who achieved CS, had 36 months' observation, or failed ITI.

Results  One-hundred prospectively enrolled patients were included in the analysis; 91 had poor prognosis factors for ITI success. The mean (standard deviation) daily ITI dose was 116.4 (61.1) IU FVIII/kg in 14 low responders (< 5 BU/mL) and 173.7 (112.0) IU FVIII/kg in 86 high responders (≥ 5 BU/mL). Inhibitor titers < 0.6 BU/mL were achieved in 71% of patients in a median of 4.01 months, accompanied by a 93% reduction in bleeding rate. ITI success was achieved by 70% of patients and 56 of 72 (78%) primary (first-line) ITI patients. PR was achieved by 5 patients; ITI failed in 25 patients. PS and CS were achieved in a median of 5.55 and 11.25 months, respectively.

Conclusions  ITI with pdFVIII/VWF led to rapid eradication of FVIII inhibitors, normalization of FVIII pharmacokinetics in the majority of patients, and a significant reduction in bleeding rates.

Clinical application of extended half-life factor VIII in children with severe haemophilia A

INTRODUCTION

Only few studies have presented results from real-world clinical use of Extended Half-Life (EHL) products in children with haemophilia (CWH).

AIM

To retrospectively examine real-life experience with EHL factor VIII products use in CWH A, comparing with clinical experience from standard half-life products (SHL).

METHODS

A retrospective review of medical records of CWH A who have been prescribed EHL factor concentrates was conducted. All before/after comparisons were performed with the Wilcoxon matched-pairs signed-ranks test.

RESULTS

Twenty-three children with severe haemophilia A were enrolled in the study (3-6 years old: n = 4, 7-12 years old: n = 7 and 13-18 years old: n = 12). Median length of time that patients were treated with EHL products was 78 weeks. Median dosing interval was significantly lengthened from 2.3 to 3.5 days after switching from SHL to EHL concentrates. Mean trough FVIII levels were significantly increased from 2.3% to 4.1% after treatment with EHL products. Also, CWH A had a reduction of mean annual bleeding rate (ABR) and mean annual joint bleeding rate (AJBR) from 1 and .8 to .3 and .2, respectively, following treatment with EHL concentrates (ABR: p = .02, AJBR: p = .05). However, after switching to factor EHL, actual FVIII consumption, including bleeds, was significantly increased from 94 IU/kg/week to 118 IU/kg/week in CWH A. There was no inhibitor development.

CONCLUSION

This study demonstrates the successful transition of 23 CWH A from SHL to EHL factor concentrates.

Eradication of FIX inhibitor in haemophilia B children using low-dose immune tolerance induction with rituximab-based immunosuppressive agent(s) in China

INTRODUCTION

Development of haemophilia B inhibitors (HBI) results in the ineffectiveness of FIX replacement therapy. Inhibitor eradication by immune tolerance induction (ITI) is therefore necessary. In HBI, ITI even at high FIX dose is less effective and has a higher risk of severe complications.

AIM

To characterize clinical features and outcome of ITI on HBI.

METHODS

This retrospective study was conducted in Haemophilia Paediatric Comprehensive Care Centre of China. We used low-dose ITI (25-50 FIX IU/kg/three-times-weekly to every-other-day) with domestic prothrombin complex concentrate (PCC), combined with two successive immunosuppressive (IS) regimens.

RESULTS

Sixteen HBI children, representing 5.7% of all and 14.4% of our severe registered HB patients, were enroled. Seven cases reported allergic reactions (ARs) proximal to inhibitor development. The historic peak inhibitor titre was median 54.2 (range 4.7-512) BU, and 15 (93.8%) had high-titre inhibitors. Twelve patients adherent to ITI were analysable. Of the nine ITI patients who received rituximab/prednisone (IS Regimen-1), four achieved tolerization in 1.4-43.3 months. Two subsequently relapsed but re-tolerized after a second course of IS Regimen-1. During ITI, the median treated bleed was .39/month (82.7% reduction from before ITI), and the incidence of AR and nephrotic syndrome (NS) complications was each at 22% (2/9). Three ITI patients received modified 'Beutel' protocol (IS Regimen-2) using multiple-IS-drugs, and two had rapid tolerization (.8 and 1.8 months).

CONCLUSIONS

Inhibitor eradication could be achieved by low-dose ITI protocol using PCC combined with IS. Larger studies are needed to confirm if ITI with IS Regimen-2 is more effective with less complications.