Non-clotting factor therapies for preventing bleeds in people with congenital hemophilia A or B

BACKGROUND

Management of congenital hemophilia A and B is by prophylactic or on-demand replacement therapy with clotting factor concentrates. The effects of newer non-clotting factor therapies such as emicizumab, concizumab, marstacimab, and fitusiran compared with existing standards of care are yet to be systematically reviewed.

OBJECTIVES

To assess the effects (clinical, economic, patient-reported, and adverse outcomes) of non-clotting factor therapies for preventing bleeding and bleeding-related complications in people with congenital hemophilia A or B compared with prophylaxis with clotting factor therapies, bypassing agents, placebo, or no prophylaxis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, electronic databases, conference proceedings, and reference lists of relevant articles and reviews. The date of the last search was 16 August 2023.

SELECTION CRITERIA

Randomized controlled trials (RCTs) evaluating people with congenital hemophilia A or B with and without inhibitors, who were treated with non-clotting factor therapies to prevent bleeds.

DATA COLLECTION AND ANALYSIS

Two review authors independently reviewed studies for eligibility, assessed risk of bias, and extracted data for the primary outcomes (bleeding rates, health-related quality of life (HRQoL), adverse events) and secondary outcomes (joint health, pain scores, and economic outcomes). We assessed the mean difference (MD), risk ratio (RR), 95% confidence interval (CI) of effect estimates, and evaluated the certainty of the evidence using GRADE.

MAIN RESULTS

Six RCTs (including 397 males aged 12 to 75 years) were eligible for inclusion. Prophylaxis versus on-demand therapy in people with inhibitors Four trials (189 participants) compared emicizumab, fitusiran, and concizumab with on-demand therapy in people with inhibitors. Prophylaxis using emicizumab likely reduced annualized bleeding rates (ABR) for all bleeds (MD -22.80, 95% CI -37.39 to -8.21), treated bleeds (MD -20.40, 95% CI -35.19 to -5.61), and annualized spontaneous bleeds (MD -15.50, 95% CI -24.06 to -6.94), but did not significantly reduce annualized joint and target joint bleeding rates (AjBR and AtjBR) (1 trial; 53 participants; moderate-certainty evidence). Fitusiran also likely reduced ABR for all bleeds (MD -28.80, 95% CI -40.07 to -17.53), treated bleeds (MD -16.80, 95% CI -25.80 to -7.80), joint bleeds (MD -12.50, 95% CI -19.91 to -5.09), and spontaneous bleeds (MD -14.80, 95% CI -24.90 to -4.71; 1 trial; 57 participants; moderate-certainty evidence). No evidence was available on the effect of bleed prophylaxis using fitusiran versus on-demand therapy on AtjBR. Concizumab may reduce ABR for all bleeds (MD -12.31, 95% CI -19.17 to -5.45), treated bleeds (MD -10.10, 95% CI -17.74 to -2.46), joint bleeds (MD -9.55, 95% CI -13.55 to -5.55), and spontaneous bleeds (MD -11.96, 95% CI -19.89 to -4.03; 2 trials; 78 participants; very low-certainty evidence), but not target joint bleeds (MD -1.00, 95% CI -3.26 to 1.26). Emicizumab prophylaxis resulted in an 11.31-fold increase, fitusiran in a 12.5-fold increase, and concizumab in a 1.59-fold increase in the proportion of participants with no bleeds. HRQoL measured using the Haemophilia Quality of Life Questionnaire for Adults (Haem-A-QoL) physical and total health scores was improved with emicizumab, fitusiran, and concizumab prophylaxis (low-certainty evidence). Non-serious adverse events were higher with non-clotting factor therapies versus on-demand therapy, with injection site reactions being the most frequently reported adverse events. Transient antidrug antibodies were reported for fitusiran and concizumab. Prophylaxis versus on-demand therapy in people without inhibitors Two trials (208 participants) compared emicizumab and fitusiran with on-demand therapy in people without inhibitors. One trial assessed two doses of emicizumab (1.5 mg/kg weekly and 3.0 mg/kg bi-weekly). Fitusiran 80 mg monthly, emicizumab 1.5 mg/kg/week, and emicizumab 3.0 mg/kg bi-weekly all likely resulted in a large reduction in ABR for all bleeds, all treated bleeds, and joint bleeds. AtjBR was not reduced with either of the emicizumab dosing regimens. The effect of fitusiran prophylaxis on target joint bleeds was not assessed. Spontaneous bleeds were likely reduced with fitusiran (MD -20.21, 95% CI -32.12 to -8.30) and emicizumab 3.0 mg/kg bi-weekly (MD -15.30, 95% CI -30.46 to -0.14), but not with emicizumab 1.5 mg/kg/week (MD -14.60, 95% CI -29.78 to 0.58). The percentage of participants with zero bleeds was higher following emicizumab 1.5 mg/kg/week (50% versus 0%), emicizumab 3.0 mg/kg bi-weekly (40% versus 0%), and fitusiran prophylaxis (40% versus 5%) compared with on-demand therapy. Emicizumab 1.5 mg/kg/week did not improve Haem-A-QoL physical and total health scores, EQ-5D-5L VAS, or utility index scores (low-certainty evidence) when compared with on-demand therapy at 25 weeks. Emicizumab 3.0 mg/kg bi-weekly may improve HRQoL measured by the Haem-A-QoL physical health score (MD -15.97, 95% CI -29.14 to -2.80) and EQ-5D-5L VAS (MD 9.15, 95% CI 2.05 to 16.25; 1 trial; 43 participants; low-certainty evidence). Fitusiran may result in improved HRQoL shown as a reduction in Haem-A-QoL total score (MD -7.06, 95% CI -11.50 to -2.62) and physical health score (MD -19.75, 95% CI -25.76 to -11.94; 1 trial; 103 participants; low-certainty evidence). The risk of serious adverse events in participants without inhibitors also likely did not differ following prophylaxis with either emicizumab or fitusiran versus on-demand therapy (moderate-certainty evidence). Transient antidrug antibodies were reported in 4% (3/80) participants to fitusiran, with no observed effect on antithrombin lowering. A comparison of the different dosing regimens of emicizumab identified no differences in bleeding, safety, or patient-reported outcomes. No case of treatment-related cancer or mortality was reported in any study group. None of the included studies assessed our secondary outcomes of joint health, clinical joint function, and economic outcomes. None of the included studies evaluated marstacimab.

AUTHORS' CONCLUSIONS

Evidence from RCTs shows that prophylaxis using non-clotting factor therapies compared with on-demand treatment may reduce bleeding events, increase the percentage of individuals with zero bleeds, increase the incidence of non-serious adverse events, and improve HRQoL. Comparative assessments with other prophylaxis regimens, assessment of long-term joint outcomes, and assessment of economic outcomes will improve evidence-based decision-making for the use of these therapies in bleed prevention.

In vivo genome editing using 244-cis LNPs and low-dose AAV achieves therapeutic threshold in hemophilia A mice

Gene therapy and rebalancing therapy have emerged as promising approaches for treating hemophilia A, but there are limitations, such as temporary efficacy due to individual differences. Genome editing for hemophilia has shown long-term therapeutic potential in preclinical trials. However, a cautious approach is necessary because genome editing is irreversible. Therefore, we attempted to induce low-level human factor 8 (hF8) gene knockin (KI) using 244-cis lipid nanoparticles and low-dose adeno-associated virus to minimize side effects and achieve a therapeutic threshold in hemophilia A mice. We selected the serpin family C member 1, SerpinC1, locus as a target to enable a combined rebalancing strategy with hF8 KI to augment efficacy. This strategy improved blood coagulation activity and reduced hemophilic complications without adverse effects. Furthermore, hemophilic mice with genome editing exhibit enhanced survival for 40 weeks. Here, we demonstrate an effective, safe, and sustainable treatment for hemophilia A. This study provides valuable information to establish safe and long-term genome-editing-mediated treatment strategies for treating hemophilia and other protein-deficient genetic diseases.

Foam roller-based self-induced myofascial therapy in patients with hemophilic knee arthropathy: a multicenter, single-blind, randomized clinical study

BACKGROUND

Hemophilia is a congenital coagulopathy characterized by degenerative joint damage. Self-induced myofascial therapy aims to decrease pain and improve tissue mobility, functionality and proprioception.

AIM

The aim of this study was to evaluate the safety and efficacy of self-induced myofascial release in patients with hemophilic knee arthropathy.

DESIGN

This is a randomized clinical study.

SETTING

This study was carried out in different patient associations.

POPULATION

Fifty-two patients with hemophilia were included in the study.

METHODS

Patients were randomized to the experimental group (daily home protocol of foam roller-based self-induced myofascial therapy for 8 weeks) or the control group (no intervention). The variables were the frequency of hemarthrosis (self-reporting), pain intensity (visual analog scale), range of motion (goniometry) and muscle strength (dynamometry). All variables were evaluated at baseline, post-treatment and after a 10-week follow-up.

RESULTS

The patients included in the experimental group showed significant improvements in terms of a decrease in frequency of hemarthrosis (mean difference [MD]=-0.61; 95% confidence interval [CI]: -0.81; -0.41) and pain intensity (MD=-0.33; 95% CI: -0.48, -0.18), increased range of motion (MD=0.88; 95% CI: 0.39; 1.37), strength in quadriceps (MD=0.88; 95% CI: 0.39; 1.37). (MD=12.39; 95% CI: 3.44; 21.34) and hamstrings (MD=7.85; 95% CI: 0.60; 15.11). There were intergroup differences in the frequency of hemarthrosis (F=14.51; P<0.001), pain intensity (F=9.14; P<0.001) and range of motion (F=13.58; P<0.001).

CONCLUSIONS

Self-induced myofascial therapy can be an effective complementary technique in the treatment of patients with hemophilic arthropathy. Self-induced myofascial therapy can reduce the frequency of knee hemarthrosis in patients with hemophilia. This technique can improve pain intensity and range of motion in patients with hemophilic knee arthropathy.

CLINICAL REHABILITATION IMPACT

Hemophilic knee arthropathy is characterized by chronic pain, decreased range of motion, and periarticular muscle atrophy. Foam roller-based self-induced myofascial therapy can reduce the frequency of hemarthrosis and pain intensity and improve range of motion in patients with hemophilic arthropathy. Foam roller-based self-induced myofascial therapy is safe and effective in the treatment of patients with hemophilia. The inclusion of self-induced myofascial therapy exercises in the approach to degenerative joint pathologies may be an effective and safe treatment option.

Comprehensive Analysis of Hemophilia A (CAHEA): Towards Full Characterization of the F8 Gene Variants by Long-Read Sequencing

BACKGROUND

 Hemophilia A (HA) is the most frequently occurring X-linked bleeding disorder caused by heterogeneous variants in the F8 gene, one of the largest genes known. Conventional molecular analysis of F8 requires a combination of assays, usually including long-range polymerase chain reaction (LR-PCR) or inverse-PCR for inversions, Sanger sequencing or next-generation sequencing for single-nucleotide variants (SNVs) and indels, and multiplex ligation-dependent probe amplification for large deletions or duplications.

MATERIALS AND METHODS

 This study aimed to develop a LR-PCR and long-read sequencing-based assay termed comprehensive analysis of hemophilia A (CAHEA) for full characterization of F8 variants. The performance of CAHEA was evaluated in 272 samples from 131 HA pedigrees with a wide spectrum of F8 variants by comparing to conventional molecular assays.

RESULTS

 CAHEA identified F8 variants in all the 131 pedigrees, including 35 intron 22-related gene rearrangements, 3 intron 1 inversion (Inv1), 85 SNVs and indels, 1 large insertion, and 7 large deletions. The accuracy of CAHEA was also confirmed in another set of 14 HA pedigrees. Compared with the conventional methods combined altogether, CAHEA assay demonstrated 100% sensitivity and specificity for identifying various types of F8 variants and had the advantages of directly determining the break regions/points of large inversions, insertions, and deletions, which enabled analyzing the mechanisms of recombination at the junction sites and pathogenicity of the variants.

CONCLUSION

 CAHEA represents a comprehensive assay toward full characterization of F8 variants including intron 22 and intron 1 inversions, SNVs/indels, and large insertions and deletions, greatly improving the genetic screening and diagnosis for HA.

Perioperative Management of Spontaneous Intracranial Hemorrhage in a Patient With Hemophilia A in a Resource Limited Country

Intracranial hemorrhage (ICH) is a serious complication of hemophilia A with high morbidity and mortality. The management of such cases is complicated by nonspecific and often delayed presentation, increased frequency of rebleeding, low awareness regarding clotting factor replacement, and debate regarding the efficacy of surgical interventions. We report a case of an 18-year-old male patient with hemophilia A, who first presented to the emergency department in India in a comatose state. Neuroimaging revealed subdural hematoma with midline shift and uncal herniation. The patient was successfully managed with perioperative cryoprecipitate and factor VIII replacement, tiered intracranial pressure lowering strategies, and early decompressive craniectomy with clot evacuation. In India, there are no standardized guidelines for screening and routine care for hereditary diseases like hemophilia. In a resource-deficient country, management was complicated by the limited availability of factor VIII in the emergent setting, as well as the inability to obtain serial factor levels in the postoperative period. We hope that this article helps to guide the management of ICH and hemophilia in resource-limited countries.

On-Demand Treatment

INTRODUCTION

Prophylactic clotting factor infusion regimens to prevent bleeding and joint deformity has become the standard of care in severe hemophilia A patients.

AIM

To assess low-dose factor prophylaxis in our population as an alternative approach to managing severe hemophilia A.

METHODS

A prospective cohort study that included 68 hemophilia A patients divided into two groups, i.e., Prophylaxis and on-demand. The two groups were compared for annualized bleeding rate (ABR), hospitalization, units of factor VIII (FVIII) infused, or plasma products transfused, i.e., fresh frozen plasma (FFP) and cryoprecipitate (CP), and development of FVIII inhibitors.

RESULTS

Of the 68 patients recruited in this study, 25 (36.7%) were in the prophylaxis group, and 43(63.3%) were in the on-demand group. The on-demand group presented a higher median-IQR ABR [8(20-3) vs. 5(10-1.5), p-value 0.024], several hospitalizations (39.7% vs. 0, p-value 0.001), and inhibitor development (9.3% vs. 0, p-value 0.289) compared to the prophylaxis group. The prophylaxis approach demonstrated a significant negative correlation of ABR with FVIII prophylaxis (r=-0484, p=value=0.014). Moreover, no hospitalizations or inhibitor development was observed in the prophylaxis group. The estimated annual consumption of FVIII was 328 IU/kg/year in the on-demand group and 1662.6 IU/kg/year in the prophylaxis group. However, a highly significant difference in plasma product utilization was observed between the two groups, i.e., p-value <0.001 and 0.038 for FFP and CP, respectively.

CONCLUSION

Low-dose factor prophylaxis resulted in improved outcomes compared to on-demand treatment in terms of ABR, joint bleeding, hospitalization, and the development of inhibitors. This treatment approach should be adopted as an economically feasible alternative to high-dose Prophylaxis in resource-constrained countries.

Acquired Hemophilia A Masquerading as Bleeding on Anticoagulation: A Case Report Including Key Laboratory Considerations

We report a case of a patient with recurrent hematomas while on anticoagulation for a pulmonary embolism and a prolonged hospital stay due to a delayed diagnosis for acquired hemophilia A. Acquired hemophilia A is a rare autoimmune bleeding disorder with autoantibodies directed against coagulation factor VIII (FVIII), leading to an acquired FVIII deficiency. A prolonged isolated activated partial thromboplastin time (aPTT) in a bleeding patient warrants workup for acquired hemophilia A. This is specifically challenging in patients with thrombosis on anticoagulation and can lead to significant delays in diagnosis and associated morbidities. The case highlights the need for further awareness of this disease, potential laboratory pitfalls when conducting and interpreting coagulation assays, and the management considerations in a patient with a simultaneous thrombotic and hemorrhagic condition.

A novel F8 variant in a Chinese hemophilia A family and involvement of X-chromosome inactivation: A case report

RATIONALE

Hemophilia A (HA) is an X-linked recessive bleeding disorder, which shows factor VIII (FVIII) deficiency caused by genetic variant in F8 gene.

PATIENT CONCERNS

Males with F8 variants are affected, whereas female carriers with a wide range of FVIII levels are usually asymptomatic, it is possible that different X-chromosome inactivation (XCI) may effect the FVIII activity.

DIAGNOSES

We identified a novel variant F8: c.6193T > G in a Chinese HA proband, it was inherited from the mother and grandmother with different FVIII levels.

INTERVENTIONS

We performed Androgen receptor gene (AR) assays and RT-PCR.

OUTCOMES

AR assays revealed that the X chromosome with the F8 variant was severely skewed inactivated in the grandmother with higher FVIII levels, but not in the mother with lower FVIII levels. Further, RT-PCR of mRNA confirmed that only the wild allele of F8 was expressed in the grandmother, with lower expression in the wild allele of the mother.

LESSONS

Our findings suggest that F8: c.6193T > G could be the cause of HA and that XCI affected the FVIII plasma levels in female carriers.

Acquired Hemophilia A and ST-Elevation Myocardial Infarction (STEMI): A Rare Presentation and Management Dilemma

Thrombotic events are a rare complication of recombinant activated factor VII (rFVIIa) therapy in patients with hemophilia. We present a case of a 71-year-old male who developed ST-elevation myocardial infarction after receiving rFVIIa replacement therapy for acquired hemophilia A.

In Vitro FVIII Encoding Transgenic Mesenchymal Stem Cells Maintain A Successful Coagulation in FVIII- Deficient Plasma Mimicking Hemophilia A

Objective

Hemophilia A is an X-linked recessive bleeding disorder caused by deficiency of plasma coagulation factor VIII (FVIII), and accounts for about 80-85% of patients with hemophilia. Plasma-derived therapies or recombinant factor VIII concentrates and also FVIII mimicking antibodies are used to prevent and treat the bleeding symptoms. Recently, EMA granted a conditional marketing approval for the first gene therapy of Hemophilia A. Aim of this study was to determine the effectiveness of coagulation in correcting FVIII deficiency with FVIII secreting transgenic mesenchymal stem cells (MSC).

Materials and Methods

A lentiviral vector encoding B-domain-deleted Factor VIII cDNA sequence with CD45 R0 truncated (CD45R0t) surface marker was designed to develop a transgenic FVIII expressing primary cell line by transducing MSC. Efficacy and functionality of secreted FVIII from MSCs was assessed with anti- FVIII ELISA, CD45R0t flow cytometry, FVIII Western Blot and Mixing Test analysis in vitro.

Results

Results of this study showed that the transgenic MSCs maintain a persistent FVIII secretion. There was no significant difference in FVIII secretion over time, suggesting stable FVIII expression from the MSCs. Functionality of FVIII protein secreted in MSC supernatant was demonstrated by using Mixing Test in coagulation analysis. In the Mixing Test analysis, FVIIIdeficient human plasma products were mixed either with saline control or FVIII-secreted MSC supernatant. Mean FVIII levels of saline control group were 0.41±0.03 IU/dL whereas mean FVIII levels were 25.41±33.38 IU/dL (p<0.01) in FVIII-secreting MSC supernatant mixed group. Mean activated partial thromboplastin time (aPTT) of saline control group was 92.69±11.38 seconds whereas in FVIII-secreting MSC supernatant mixed group, mean aPTT levels were decreased to 38.60±13.38 seconds (p<0.001).

Conclusion

Findings of this in vitro study shows a promising new method applicable to treat Hemophilia A. Accordingly, a FVIII secreting transgenic mesenchymal stem cell study will be initiated in FVIII knock-out animal model.

Limited sampling strategies for individualized BAX 855 prophylaxis in severe hemophilia A: in silico evaluation

OBJECTIVE

Limited sampling strategies (LSS) lower the burden of pharmacokinetic (PK)-guided dosing, but an extensive evaluation of LSS for BAX 855 (Adynovi) is currently lacking. This study aimed to develop a LSS for BAX 855 and combine this with a LSS of a standard half-life (SHL) factor VIII (FVIII) concentrate in a clinical setting.

METHODS

Individual PK parameters of BAX 855 were estimated for 10 000 virtual patients with severe hemophilia A using Monte Carlo simulations. Several LSS consisting of 2-6 samples were examined based on patient burden, bias and accuracy of clearance, elimination half-life, volume of distribution and trough levels at 72 h (C72). Analyses were performed separately for adults and children <12 years.

RESULTS

The preferred LSS for BAX 855 consisted of three sampling points at 15-30 min, 48 h and 72 h for both adults (mean accuracy C72: 14.0% vs. 10.8% using six samples) and children (mean accuracy C72: 14.9% vs. 11.4% using six samples). The best strategy with two samples (peak, 48 h) resulted in an adequate, but lower accuracy than strategies with ≥3 samples (mean accuracy C72: 22.3%). The optimal combination of the LSS of SHL FVIII and BAX 855 led to six samples during four clinical visits.

CONCLUSION

This in silico study has identified that two to three samples are necessary to estimate the individual PK of BAX-855 adequately. These samples can be collected in one or two clinical visits. When combining PK profiling of SHL FVIII and BAX 855, six samples during four clinical visits are needed.

Acute coronary syndrome management in hemophiliacs: How to maintain balance?: A review

To analyze existing literature and understand how to balance the minimization of bleeding risk and ensuring adequate anticoagulation during coronary intervention treatment and long-term postoperative anticoagulation in hemophilia patients during the perioperative period, in order to provide guidance for healthcare professionals in developing effective treatment plans. This narrative review will analyze existing studies, case reports, and clinical guidelines to determine the most effective strategies for managing acute coronary syndrome in hemophilia patients. When evaluating the literature, factors such as patient age, medical history, and severity of the condition will be considered. The current management guidelines for acute coronary syndrome in hemophilia patients are not based on systematic evaluation and mainly rely on expert opinions. This article provides a comprehensive analysis of existing literature and recommends coagulation factor replacement therapy before anticoagulation and intervention treatment, as well as personalized anticoagulation treatment during the postoperative period for better management of hemophilia patients with acute coronary syndrome. These recommendations can help healthcare professionals develop more effective treatment plans for hemophilia patients.

Resonant Acoustic Rheometry to Measure Coagulation Kinetics in Hemophilia A and Healthy Plasma: A Novel Viscoelastic Method

Compared with conventional coagulation tests and factor-specific assays, viscoelastic hemostatic assays (VHAs) can provide a more thorough evaluation of clot formation and lysis but have several limitations including clot deformation. In this proof-of-concept study, we test a noncontact technique, termed resonant acoustic rheometry (RAR), for measuring the kinetics of human plasma coagulation. Specifically, RAR utilizes a dual-mode ultrasound technique to induce and detect surface oscillation of blood samples without direct physical contact and measures the resonant frequency of the surface oscillation over time, which is reflective of the viscoelasticity of the sample. Analysis of RAR results of normal plasma allowed defining a set of parameters for quantifying coagulation. RAR detected a flat-line tracing of resonant frequency in hemophilia A plasma that was corrected with the addition of tissue factor. Our RAR results captured the kinetics of plasma coagulation and the newly defined RAR parameters correlated with increasing tissue factor concentration in both healthy and hemophilia A plasma. These findings demonstrate the feasibility of RAR as a novel approach for VHA, providing the foundation for future studies to compare RAR parameters to conventional coagulation tests, factor-specific assays, and VHA parameters.

BAY 81-8973 Efficacy and Safety in Previously Untreated and Minimally Treated Children with Severe Hemophilia A: The LEOPOLD Kids Trial

INTRODUCTION

 BAY 81-8973, a full-length recombinant factor VIII for hemophilia A treatment, has been extensively evaluated in previously treated patients in the LEOPOLD (Long-Term Efficacy Open-Label Program in Severe Hemophilia A Disease) clinical trials.

AIM

 To assess BAY 81-8973 efficacy and safety when used for bleed prophylaxis and treatment in previously untreated/minimally treated patients (PUPs/MTPs).

METHODS

 In this phase III, multicenter, open-label, uncontrolled study, PUPs/MTPs (<6 years old) with severe hemophilia A received BAY 81-8973 (15-50 IU/kg) at least once weekly as prophylaxis. Primary efficacy endpoint was the annualized bleeding rate (ABR) within 48 hours after prophylaxis infusion. Adverse events and immunogenicity were assessed. Patients who developed inhibitors were offered immune tolerance induction (ITI) treatment in an optional extension phase.

RESULTS

 Fifty-two patients were enrolled, with 43 patients (mean age: 13.6 months) treated. Median (interquartile range) ABR for all bleeds within 48 hours of prophylaxis infusion was 0.0 (0.0-1.8) among patients without inhibitors (n = 20) and 0.0 (0.0-2.2) among all patients. As expected, inhibitors were the most frequent treatment-related adverse event (high titer: 17 [39.5%] patients; low titer: 6 [13.9%] patients). Six of 12 patients who underwent ITI treatment in the extension phase (high titer [n = 5], low titer [n = 1]) achieved a negative inhibitor titer.

CONCLUSION

 BAY 81-8973 was effective for bleed prevention and treatment in PUPs/MTPs. The observed inhibitor rate was strongly influenced by a cluster of inhibitor cases, and consequently, slightly higher than in other PUP/MTP studies. Overall, the BAY 81-8973 benefit-risk profile remains unchanged and supported by ongoing safety surveillance. Immune tolerance can be achieved with BAY 81-8973.

The development of ankylosing spondylitis in a patient with familial hemophilia

Hemophilia is a rare inherited disease which causes bleeding due to Factor VIII or Factor IX deficiency. It is usually X-linked recessive and typically affects males. Arthropathy occurs as a result of cartilage damage and chronic synovitis due to recurrent intra-articular bleeding in hemophilic patients and is mostly seen in the knee, shoulder, hip and ankle joints. There are many other diseases that cause chronic synovitis ankylosing spondylitis (AS), which is a subtype of spondyloarthropathies that cause chronic low back pain, more common in men younger than 45 years of age. In addition to axial involvement, peripheral arthritis, uveitis, enthesitis and dactylitis can be seen. Although the etiology is not fully known, genetic and environmental factors are responsible for the pathogenesis. In this study, we aimed to present congenital hemophilia and AS coexistence in a 22-year-old male patient.

Association between Sports Participation, Factor VIII Levels and Bleeding in Hemophilia A

BACKGROUND

 Little is known on how sports participation affects bleeding risk in hemophilia. This study aimed to examine associations between sports participation, factor VIII (FVIII) levels and bleeding in persons with hemophilia A.

METHODS

 In this observational, prospective, single-center study, persons with hemophilia A who regularly participated in sports were followed for 12 months. The associations of patient characteristics, FVIII levels, and type/frequency of sports participation with bleeding were analyzed by repeated time-to-event modelling.

RESULTS

 One hundred and twelve persons (median age: 24 years [interquartile range:16-34], 49% severe, 49% on prophylaxis) were included. During follow-up, 70 bleeds of which 20 sports-induced were observed. FVIII levels were inversely correlated with the bleeding hazard; a 50% reduction of the baseline bleeding hazard was observed at FVIII levels of 3.1 and a 90% reduction at 28.0 IU/dL. The bleeding hazard did not correlate with sports participation. In addition, severe hemophilia, prestudy annual bleeding rate, and presence of arthropathy showed a positive association with the bleeding hazard.

CONCLUSION

 This analysis showed that FVIII levels were an important determinant of the bleeding hazard, but sports participation was not. This observation most likely reflects the presence of adequate FVIII levels during sports participation in our study. Persons with severe hemophilia A exhibited a higher bleeding hazard at a similar FVIII levels than nonsevere, suggesting that the time spent at lower FVIII levels impacts overall bleeding hazard. These data may be used to counsel persons with hemophilia regarding sports participation and the necessity of adequate prophylaxis.

Impact of different factor VIII inhibitor kinetic profiles on the inhibitor titer quantification using the modified Nijmegen–Bethesda assay

Background

Coagulation factor VIII (FVIII) inhibitor titer quantification is vital for optimizing care in people with hemophilia A.

Objectives

This study analyzed the impact of the different kinetic profiles of four FVIII monoclonal antibodies on inhibitor titer quantification using the modified Nijmegen–Bethesda assay.

Methods

Concentration‐related and time‐related profiles of FVIII antibodies (4A4, BO2C11, 2‐54, ESH‐8) were evaluated in vitro. FVIII residual activity was measured using a one‐stage clotting assay and chromogenic substrate assay. Profiles of the FVIII antibodies were compared with the theoretical kinetic model: the ideal log (residual activity)‐linear (inhibitor concentration) relationship. Different theoretical kinetic model–dependent and –independent criteria to calculate FVIII inhibitor titer were compared.

Results

Factor VIII monoclonal antibodies had different concentration‐related and time‐related profiles, ideal for comparative analysis using the modified Nijmegen–Bethesda assay. The kinetic profile of 4A4 was similar to the theoretical kinetic model, while BO2C11 showed a steeper curve, and 2‐54 and ESH‐8 a flatter curve, than the model. In the modified Nijmegen–Bethesda assay, conversion of measured FVIII residual activities for different inhibitor dilutions into FVIII inhibitor titer is based on the theoretical kinetic model. Therefore, titer calculations for FVIII inhibitors that deviate from the model are prone to underestimation or overestimation. Calculating a theoretical dilution at 50% FVIII residual activity by sigmoidal regression reflecting different kinetic inhibition profiles can provide a more accurate titer result.

Conclusion

Kinetic profiles of FVIII antibodies can deviate from the theoretical kinetic model in the modified Nijmegen–Bethesda assay, leading to differences in FVIII inhibitor titer quantification.

Bilateral synchronous total hip arthroplasty for end-stage arthropathy in hemophilia A patients: A retrospective study

Total hip arthroplasty (THA) has been an effective tool of advanced hemophiliac hip arthritis. There are only limited data of bilateral synchronous THA for end-stage arthropathy in hemophilia A patients. The aim of this retrospective study was to analyze clinical outcome and complication rate of bilateral THA for hemophilia A patients with end-stage arthropathy of hip and review the operative strategy. From August 2012 to July 2016, 48 hips of 24 patients with hemophilia A patients underwent THA by a single experienced chief orthopedic surgeon. Clinical and radiological evaluations were included of operation time, blood loss, the quantity of blood transfusion, clotting factor consumption, duration of hospitalization, modified Harris hip score, complication rate, and radiographic assessment. All the 24 patients successfully completed the operation, followed up for 5 to 8 years, and the mean time was 6.5 years. The average operation time was 140 minutes (range, 120-180 minutes). The average total blood loss was 225 mL (range, 150-400 mL). The mean red blood cell transfusion amount was 2.4 U (range, 0-6 U). the mean hospitalization time was 24 days (range, 16-46 days). The mean amount of clotting factor VIII used in the perioperative period for management of hemophilia A was 30,600 U (range, 18,000-52,000 U). Average modified Harris hip score increased from 46.6 (range 28-70) points preoperatively to 90.2 (range 75-98) points at final follow-up, complications were few. With excellent operative techniques and hematological management, bilateral synchronous THA for end-stage arthropathy in hemophilia A patients can provide satisfactory outcomes.

Case Report: A Child With Hemophilia A Serves as Donor for Hematopoietic Stem Cell Transplantation to Cure His Brother's Severe Aplastic Anemia

The first-line treatment of severe aplastic anemia is allogeneic hematopoietic stem cell transplantation with a matched sibling donor. However, co-morbidities of the identical donor can make donation difficult. We present a transplantation where in parallel with the patient's conditioning treatment, the preparation of the donor with severe hemophilia A required a special management with perioperative factor VIII substitution. Donation was successful without complications, and 18 months after transplantation, the patient and his donor are well without any long-term sequelae. To our knowledge, this is the first reported succesfull transplantation with hemophilic child serving as a bone marrow donor. The procedure did not mean a significant risk to donor health, so donors with hemophilia should not be excluded from donation.

Assessment of Oral Health and Healthy Habits in Adult Patients with Congenital Hemophilia

OBJECTIVES

 The objective of our study was to assess the current knowledge, the oral health status, and the pro-health needs of patients with hemophilia.

MATERIALS AND METHODS

 The study included 77 patients with known hemophilia. The study included the assessment of dental indicators related to caries incidence (decayed, missing, and filled teeth [DMFT] and decayed, missing, and filled permanent teeth or surfaces [DMFS]), caries treatment (treatment index), oral hygiene status (Approximal Plaque Index [API] and simplified oral hygiene index [OHI-S]), and periodontal status (bleeding on probing [BoP]). A questionnaire addressed symptoms of hemorrhagic diathesis and health-promoting habits. The influence of routine management ("on-demand" vs. prophylactic therapy), type of hemophilia (A, B), and severity of clotting factor deficiency (mild, moderate, or severe) on oral health was assessed.

STATISTICAL ANALYSIS

 The tests used in the study were Shapiro-Wilk, Mann-Whitney, Kruskal-Wallis, and Dunn's tests. The level of significance was set at p < 0.05.

RESULTS

 Patients with hemophilia showed a higher prevalence of caries compared with patients without hemorrhagic diathesis (DMFT 14 and 9, and DMFS 30 and 15, respectively), and they also presented a higher bleeding index value during probing and worse effectiveness of hygienic interdental procedures. The type of therapy and secondary prophylaxis used and the type and severity of hemophilia did not affect the oral health status.

CONCLUSIONS

 Patients with hemophilia have an increased risk of developing dental caries. Undertaking educational activities related to the prevention of oral diseases is necessary to improve oral health.

Real-world experience of emicizumab prophylaxis in young children with hemophilia A: retrospective data from China

BACKGROUND

As a new non-factor therapy for hemophilia A (HA), real-world study of emicizumab is still scarce. This study aimed to investigate the real-world use of emicizumab in Chinese boys with HA.

METHODS

Patients with moderate or severe HA were enrolled at Beijing Children's Hospital. They take emicizumab weekly (3 mg/kg) for a month and then went into a maintenance period with a different dosing regimen. After obtaining platelet-poor plasma at end of the loading period and during the maintenance period, coagulation ability and FVIII inhibitor were determined using human and bovine chromogenic Bethesda assay. Patients' bleeding rates were calculated through patients' records from 24 weeks before to at least 6 months after the switch (to emicizumab).

RESULT

In total, 13 pediatric patients with HA (severe: moderate = 11:2) were enrolled in this study. The patients' age was 3.51 (0.73-6.65) years. Eight had FVIII inhibitors at enrollment and one of them developed FVIII inhibitors again during the switch. The coagulation level of the maintenance period was 19.6 (13.5-32.8) IU/dL (N = 10). The median dose of each emicizumab injection was 2.7 (1.3-3.8) mg/kg and the monthly consumption of emicizumab was 5.2 (3.2-6.8) mg/kg/month. After switching to emicizumab, reduced annualized bleeding rate (ABR) [0.5 (0-4) vs. 4 (0-18), P < 0.01], annualized joint bleeding rate (AJBR) [0 (0-1.1) vs. 1.0 (0-12), P < 0.01], and annualized spontaneous bleeding rate (ASBR) [0 (0-1) vs. 2.0 (0-18), P < 0.01] were observed. In patients with or without FVIII inhibitor, similar ABR [0.33 (0-4) vs. 0.5 (0-3), P = 0.78], AJBR [0 (0-1.1) vs. 0 (0-0.5), P = 0.63], and ASBR [0 (0-1) vs. 0 (0-1.5), P = 0.73] were also noticed. Five inhibitor-positive patients (at enrollment) all had their inhibitor titer reduced. In addition, all target joints vanished after switching to emicizumab.

CONCLUSION

Emicizumab could reduce bleeds in pediatric patients with/without FVIII inhibitors and eliminate target joints.

A comparison between on-demand usage of rFVIIa vs prophylaxis use of emicizumab in high titer inhibitory hemophilia A patients in Iran: A cost-utility analysis

BACKGROUND

Hemophilia A (HA) is an inherited X-linked bleeding disease with costly treatment, especially for high titer inhibitory patients. Emicizumab, a new humanized bispecific antibody, has been approved for use to prevent or reduce the frequency of bleeding episodes in HA patients with inhibitors. This study evaluated the cost-utility of emicizumab prophylaxis (EP) in comparison with recombinant factor VII activated on-demand treatment in HA patients with inhibitors.

METHODS

A life-time Markov model with payer and societal perspectives was developed in different age groups with different annual bleeding rates (ABR). Efficacy of treatments were extracted from HAVEN trials. Utilities were retrieved from published evidence. Costs were calculated based on Iran food and drug administration official website, national tariff book for medical services and hospital data. One-way deterministic sensitivity analysis was performed.

RESULTS

EP was dominant choice in comparison with on-demand administration of recombinant factor VII activated in all age groups with ABR 20 and 25, and it remained dominant in patients with age 2 and age 12 at start point with ABR 16 and 17. The reported incremental cost-effectiveness ratio for the group with ABR 18 at the age 20, was 12,936 United States Dollars which is lower than the acceptable threshold of cost-effectiveness in Iran (1-3 gross domestic product per capita) and EP can be considered as cost-effective choice in this scenario.

CONCLUSION

EP was found to be a dominant and cost-effective choice for Iranian HA patients with factor VIII inhibitors with ABR 18 and above with considerable cost saving.

Feasibility of therapeutic plasma exchange-based combination therapy in the treatment of acquired hemophilia A: A retrospective 6 case series

Poor availability and a lack of affordability of bypassing agents (recombinant activated factor VII and activated prothrombin complex concentrate) in west China prompted us to investigate an alternative cost-effective combination therapy. We aimed to explore the feasibility of therapeutic plasma exchange (TPE)-based combination therapy in the treatment of acquired hemophilia A (AHA).We retrospectively investigated the clinical features of AHA in 6 patients who were treated with a combination of TPE, corticosteroids, and rituximab in our department for 9 years between January, 2011 and December, 2019.We examined 1 male and 5 female patients. The median age at diagnosis of AHA was 51 years (18-66 years). In all patients, FVIII activity levels were low (median: 1.5%; 1-3%), FVIII inhibitor titers were high (median: 24.5 BU/mL; 13.2-48.6 BU/mL), and activated partial thromboplastin time was markedly prolonged (median: 99.4 s; 60.9-110.1 s). They underwent 2 to 8 cycles of plasma exchange and were given varying combinations of dexamethasone, methylprednisolone, prednisone, and rituximab. After TPE bleeding gradually stopped, and activated partial thromboplastin time decreased. After 3 months of treatment, FVIII inhibitors completely disappeared.TPE when combined with corticosteroids and rituximab, as adjunctive immunosuppressive agents, may be an effective and reliable treatment for AHA. When there is no alternative, intensive first-line treatment including TPE may be lifesaving.

Idiopathic Acquired Hemophilia A, a Rare Cause of Bleeding: A Case Report and Literature Review

BACKGROUND Acquired hemophilia is a bleeding disorder mediated by an autoimmune process, in which antibodies against clotting factors are developed. This is a rarely suspected complex condition in which the initial manifestations are spontaneous bleeding in the skin, soft tissues, and mucosa in patients with no known history of bleeding disorders. Most of the cases are idiopathic (50%), but it can be associated with autoimmune diseases, malignancy, pregnancy, and medications. The most frequent type is mediated by inhibitors against factor VIII, followed by coagulation factor IX and XI. It is a disease with high morbidity and mortality rates without adequate treatment. Diagnosis is based on the detection of low concentrations of clotting factors and the presence of an inhibitor. CASE REPORT We present 2 cases of patients with spontaneous bleeding in whom the diagnosis of idiopathic acquired hemophilia A was made, an extensive malignancy study was performed that was negative, and the presence of autoimmunity markers (positive antinuclear antibodies (ANA)) was observed, without any another sign of autoimmune disease. They received immunosuppressive therapy with bleeding control and inhibitor eradication. CONCLUSIONS Acquired hemophilia A is a rare but potentially lethal disease, representing a medical challenge from its diagnosis to its treatment. An early recognition and treatment are fundamental because delays are associated with adverse outcomes. Optimal management includes the workup and treatment for an underlying disease, use of "bypass" agents when active bleeding presents, and inhibitor titer eradication through immunosuppressants drugs. With the present cases, we highlight the importance of considering acquired hemophilia A in older patients with similar symptoms, to achieve early diagnosis and treatment.

Peri-cardiac surgery coagulation management in a severe hemophilia A patient: A case report

RATIONALE

Hemophilia A (HA) is an X-linked recessive disorder caused by clotting factor VIII (FVIII) deficiency. There is limited data on the use of replacement therapy in cardiac surgery. Since no international guideline for anticoagulation in such patient exists, careful thought should be taken to design an individualized anticoagulation strategy.

PATIENT CONCERNS

We report a 54-year-old male with severe HA with FVIII activity of 0.8% when he was first diagnosed, who underwent successful mitral valve repair and coronary artery bypass graft with FVIII replacement perioperatively.

DIAGNOSES

Transthoracic echocardiography and coronary angiography confirmed the HA patient with the diagnosis of severe mitral valve regurgitation and left anterior descending artery stenosis.

INTERVENTIONS

Before surgery, a bolus of 1000 IU FVIII was injected, which obtained an FVIII of 80%. After induction, a 3750 IU bolus of FVIII was injected and subsequent FVIII level reached 135%. Mitral valve repair and coronary artery bypass graft with FVIII replacement were performed. After the surgery, a repeat FVIII activity level was 50.6%. The 400 mL of autologous blood and 700 mL of cardiopulmonary bypass (CPB) machine blood was returned to the patient as well as 4 units of fresh frozen plasma with an additional bolus of 1000 IU FVIII. 100 mg aspirin per day alone was given after surgery.

OUTCOMES

The patient recovered uneventfully and 1-year follow-up showed no complications.

LESSONS

The anticoagulant or antiplatelet regimen of HA patient following surgery should be individualized based on the evaluation of the risk factors for bleeding and thrombosis and the lowest FVIII activity ever recorded after FVIII replacement therapy.

Hemophilia A with a Rare Presentation of Hemarthrosis and Arthropathy Involving Multiple Joints in a Young Male Child

Hemophilia A is an X-linked hereditary bleeding disorder that is rarely encountered by most physicians and surgeons in their practice. Patients with mild hemophilia A tend to bleed profusely after surgery or trauma whereas a severe variant may manifest as spontaneous bleeding after minor trauma, mainly into the joints and muscles. However, seldom do we find a case where the patient experiences bleeding into multiple joints at the same time. In the South Asian population, the incidence of hemarthrosis in hemophilic patients holds scarce literature, making this an under-reported entity.

Acquired Hemophilia of Unknown Etiology in an Elderly Man: Case Report

BACKGROUND Acquired hemophilia is a rare but potentially dangerous bleeding disorder caused by autoantibodies against coagulation factors. It affects 1 to 1.5 per 1 million people each year. While 50% of cases could be idiopathic, other causes include malignancies, diabetes, pregnancy, infection, and autoimmune disorders. CASE REPORT We report a case of a 90-year-old male who developed a spontaneous hematoma on the dorsum of his right hand, with no prior history of trauma or any other mucosal bleeding. His activated partial thromboplastin time (aPTT) was found to be prolonged (>180 seconds) with a very low level of factor VIII (0.1%). CONCLUSIONS As workups did not identify the source, including malignancy and autoimmune diseases, of his acquired hemophilia, it is believed to be idiopathic. He was started on intravenous recombinant factor VIIa (NovoSeven) to control the bleeding in combination with an immunosuppressive therapy of cyclophosphamide and prednisolone. In approximately 10% of patients with acquired hemophilia, underlying malignancy, such as squamous cell cancer, chronic lymphocytic leukemia, non-Hodgkin lymphoma, and multiple myeloma can present and commonly develop in elderly patients. Therefore, patients diagnosed with idiopathic acquired hemophilia should be given long-term follow up.

Hemophilic arthropathy in a patient with multi-joint replacement: A case report and literature review

RATIONALE

Hemophilic arthropathy (HA) is a crucial morbidity and a major cause of joint pain and disability in patients with hemophilia A. Surgical methods, such as total joint arthroplasty, are of vital importance for end-stage HA treatment, but the feasibility and effects of multi-joint replacement surgery remain debatable.

PATIENT CONCERNS

A 24-year-old patient with advanced HA presented multiple joint pain. Physical examination revealed joint tenderness, swelling, and limited activity. Radiographs revealed bilateral knee joints and left elbow joint damage with joint space narrowing, articular facet erosion, and bone deformation.

DIAGNOSES

The patient was diagnosed with hemophilic arthropathy with multi-joint lesions.

INTERVENTIONS

The key points of this case include arthropathy in multiple joints and the management of simultaneous total multi-joint arthroplasty. We performed bilateral total knee arthroplasty and total left elbow arthroplasty simultaneously after adequate preparations. Special attention was paid to factor VIII infusion, hemorrhage control, and other safety precautions perioperatively.

OUTCOMES

After the surgery, no complications, such as infection or aseptic loosening, occurred, and the joints functioned well at follow-up.

LESSONS

The surgical outcome and safety of multi-joint replacement for HA are attested. Simultaneous multi-joint arthroplasty can ameliorate the quality of life for patients with hemophilia A.

A case report of acute inferior myocardial infarction in a patient with severe hemophilia A after recombinant factor VIII infusion

RATIONALE

The extent of protective effects of hemophilia against thrombotic events such as myocardial infarction (MI) and other acute coronary syndromes remains to be determined, as major risk factors for cardiovascular disease exist despite factor VIII (FVIII) deficiency. We present a case report of a 41-year-old male with severe hemophilia A and several cardiovascular risk factors.

PATIENT CONCERNS

This morbidly obese patient developed chest pressure, followed by chest pain and difficulty in breathing shortly after receiving on-demand treatment with intravenous recombinant FVIII (rFVIII) (turoctocog alfa) dosed per body weight.

DIAGNOSES

An electrocardiogram revealed a diagnosis of inferior ST-segment elevation MI.

INTERVENTIONS

The patient underwent an urgent coronary angiography using a radial artery approach. During the next 12 months, he received dual antiplatelet treatment, acetylsalicylic acid 100 mg, and clopidogrel 75 mg daily. His treatment for severe hemophilia A was changed to plasma-derived FVIII replacement therapy.

OUTCOMES

During this 12-month period, he experienced several small bleeds in his elbows.

CONCLUSIONS

The temporal relationship between rFVIII infusion and onset of the MI suggests a possible association; however, apart from obesity, the patient also had other major risk factors for arterial thrombosis, such as hypertension and smoking. Furthermore, atherosclerotic disease and underlying atherosclerotic changes could not be excluded with certainty. This case highlights the importance of studies assessing the impact of excess body weight on rFVIII dosing.

Two-incision laparoscopic appendectomy for a severe hemophilia A child patient with coagulation factor VII deficiency: Case report and review of literature

RATIONALE

The main complication of patients with severe hemophilia is recurrent bleeding events that usually affected musculoskeletal contractures. And replacement therapy methods were continuously improved to minimize adverse impacts brought by those complications. However, only several cases reported about the appendectomy for hemophilia A. We report a case of acute appendicitis treated by two-incision laparoscopy in a boy with hemophilia A and coagulation factor VII deficiency for the first time.

PATIENT CONCERNS

An 8y7m-old Chinese boy presented with half a day of right sided abdominal pain, fever, nausea, and vomiting.

DIAGNOSES

He received a computed tomography (CT) scan which revealed an enlarged appendix, thickened wall and appendiceal fecalith, and had received a conservative anti-bacterial treatment for his acute appendicitis but failed. He was diagnosed with hemophilia A and coagulation factor VII deficiency.

INTERVENTIONS

Two-incision laparoscopic appendectomy was made in success with a careful management of perioperative period. We monitored the clotting factor FVIII level and gave him a replacement therapy.

OUTCOMES

The patient had an uneventful recovery.

LESSONS

It is important to exclude intraabdominal or retroperitoneal hemorrhage in patients suffering from hemophilia and acute abdominal pain. Pre-operative evaluation of validity of the FVIII replacement therapy is another effective strategy to assess the safety and feasibility of applying an operation procedure. The two-incision laparoscopic appendectomy is an effective treatment for this kind of patients for its minimal trauma and fast recovery characteristics. Our report shows that laparoscopic appendectomy is feasible in a child suffering from hemophilia after adequate blood clotting factor replacement treatment.

Soluble vascular cell adhesion molecular-1 is a potential biological indicator of hemophilic arthropathy

Hemophilic arthropathy is the most common chronic complication in patients with hemophilia. The pathogenesis of hemophilic arthropathy involves the inflammatory processes associated with rheumatoid arthritis (RA). Determining the severity and/or progression of joint damage is crucial when evaluating the effect of treatment modalities. Identifying reliable biomarkers in the peripheral blood of patients with hemophilic arthropathy may be beneficial in clinical practice. Circulating soluble vascular cell adhesion molecule-1 (sVCAM-1), E-selectin, and P-selectin levels are elevated in patients with RA. Our study investigated whether these soluble adhesion molecules can be used as biological indicators in the course of joint damage in patients with hemophilia A.Patients with hemophilia A (mild, moderate, and severe) were enrolled. The plasma levels of sVCAM-1, E-selectin, and P-selectin in patients with hemophilia A and control were measured using specific enzyme-linked immunosorbent assay kits. Joint damages were evaluated using Pettersson scores.No statistically significant differences were observed in E-selectin and P-selectin levels between patients and controls. The sVCAM-1 level was significantly higher in patients with hemophilia A than in controls. The differences remained significant in patients with severe hemophilia A but not in patients with mild or moderate hemophilia A. The degree of hemophilic arthropathy was evaluated using Pettersson scores, and a score higher than 5 indicated marked arthropathy. Patients with more than 1 joint with marked arthropathy showed significantly higher sVCAM-1 levels.sVCAM-1 levels in patients with hemophilia A are associated with the severity of hemophilic arthropathy.

Rituximab for eradicating inhibitors in people with acquired haemophilia A

BACKGROUND

Acquired haemophilia A is a rare bleeding disorder caused by the development of specific autoantibodies against coagulation factor VIII. Rituximab may be an alternative approach to the treatment of acquired haemophilia by eradicating FVIII autoantibodies.

OBJECTIVES

To assess and summarise the efficacy and adverse effects of rituximab for treating people with acquired haemophilia A.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's trials registers, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and conference proceedings.Date of last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's trials registers: 01 March 2016.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of rituximab for people with acquired hemophilia A, with no restrictions on gender, age or ethnicity.

DATA COLLECTION AND ANALYSIS

No trials matching the selection criteria were eligible for inclusion.

MAIN RESULTS

No trials matching the selection criteria were eligible for inclusion.

AUTHORS' CONCLUSIONS

No randomised clinical trials of rituximab for acquired hemophilia A were found. Thus, based on the highest quality of evidence, we are not able to draw any conclusions or make any recommendations on rituximab for eradicating inhibitors in people with acquired haemophilia A. Given that undertaking randomised controlled trials in this field is a complex task, the authors suggest that, while planning such trials, clinicians treating the disease continue to base their choices on alternative, lower quality sources of evidence. The authors plan, for a future update of this review, to appraise and incorporate any randomised controlled trials, as well as other high-quality non-randomised studies.

Prophylaxis vs. on-demand treatment with BAY 81-8973, a full-length plasma protein-free recombinant factor VIII product: results from a randomized trial (LEOPOLD II)

BACKGROUND

BAY 81-8973 is a new full-length human recombinant factor VIII product manufactured with technologies to improve consistency in glycosylation and expression to optimize clinical performance.

OBJECTIVES

To demonstrate superiority of prophylaxis vs. on demand therapy with BAY 81-8973 in patients with severe hemophilia A.

PATIENTS/METHODS

In this multinational,randomized, open-label crossover study (LEOPOLD II;ClinicalTrials.gov identifier: NCT01233258), males aged 12–65 years with severe hemophilia A were randomized to twice-weekly prophylaxis (20-30 IU kg(-1)), 3-times-weekly prophylaxis (30-40 IU kg(-1)), or on-demand treatment with BAY 81-8973. Potency labeling for BAY 81-8973 was based on the chromogenic substrate assay or adjusted to the one-stage assay. Primary efficacy endpoint was annualized number of all bleeds (ABR). Adverse events (AEs)and immunogenicity were also assessed.

RESULTS

Eighty patients (on demand, n = 21; twice-weekly prophylaxis, n = 28; 3-times-weekly prophylaxis, n = 31) were treated and analyzed. Mean ± SD ABR was significantly lower with prophylaxis (twice-weekly, 5.7 ± 7.2; 3-times-weekly, 4.3 ± 6.5; combined, 4.9 ± 6.8) vs. on-demand treatment (57.7 ± 24.6; P < 0.0001, ANOVA). Median ABR was reduced by 97% with prophylaxis (twice-weekly, 4.0;3-times-weekly, 2.0; combined, 2.0) vs. on-demand treatment (60.0). Median ABR was higher with twice-weekly vs. 3-times-weekly prophylaxis during the first 6-month treatment period (4.1 vs. 2.0) but was comparable in the second 6-month period (1.1 vs. 2.0). Few patients reported treatment-related AEs (4%); no treatment-related serious AEs or inhibitors were reported.

CONCLUSIONS

Twice weekly or 3-times-weekly prophylaxis with BAY 81-8973 reduced median ABR by 97% compared with on-demand therapy, confirming the superiority of prophylaxis. Treatment with BAY 81-8973 was well tolerated.

Longitudinal changes in health-related quality of life for chronic diseases: an example in hemophilia A

BACKGROUND

Patients with well-managed rare chronic diseases such as hemophilia maintain a stable health state and health-related quality of life (HrQoL) that may be affected by acute events. Longitudinal HrQoL assessments analyzed using multivariate multilevel (MVML) modelling can determine the impact of such events on individuals (within-person effect) and identify factors influencing within-population differences (between-person effect).

OBJECTIVES

To demonstrate the application of MVML modelling in a longitudinal study of HrQoL in hemophilia A.

METHODS/DESIGN/PARTICIPANTS

Using data on 136 adults and 125 children from a two-year observational cohort study of burden of illness in US hemophilia A patients, MVML modelling determined the effect of time-invariant (sociodemographic and clinical characteristics) and time-varying factors (bleeding frequency, emergency room visits, and missed work/school days) on within-person and between-person HrQoL changes. HrQoL was assessed using the SF-12 health survey (adults) and PedsQL inventory (children) at baseline, then every 6 months.

RESULTS

In children, within-person (p < 0.0001) and between-person (p < 0.0001) psychosocial functioning was reduced by each additional bleed and missed day (within-person: p = 0.0089; between-person: p = 0.0060). Within-person physical functioning was reduced by each additional bleed (p < 0.0001), emergency room (ER) visit (p = 0.0284), and missed day (p = 0.0473). Between-persons, additional missed days (p < 0.0001) significantly decreased physical functioning. In adults, each additional missed day reduced SF-12 Health Survey mental (p = 0.0025) and physical (p = 0.0093) component summary scores. Each additional bleed also decreased physical component summary (PCS) significantly (p = 0.0093).

CONCLUSIONS

This study demonstrated the applicability of MVML modelling in identifying time-invariant and time-varying factors influencing HrQoL in a rare chronic disease population. Small but significant within-person and between-person changes in HrQoL with each additional acute event experienced were identified, which if frequent, could have a large cumulative impact. The results suggest that MVML modelling may be applied to future studies of longitudinal change in HrQoL in other rare chronic disease populations.

Factor VIIa binding to endothelial cell protein C receptor protects vascular barrier integrity in vivo

BACKGROUND

Recent studies have shown that factor VIIa binds to endothelial cell protein C receptor(EPCR), a cellular receptor for protein C and activated protein C. At present, the physiologic significance of FVIIa interaction with EPCR in vivo remains unclear.

OBJECTIVE

To investigate whether exogenously administered FVIIa, by binding to EPCR, induces a barrier protective effect in vivo.

METHODS

Lipopolysaccharide(LPS)-induced vascular leakage in the lung and kidney,and vascular endothelial growth factor (VEGF)-induced vascular leakage in the skin, were used to evaluate the FVIIa-induced barrier protective effect. Wild-type, EPCR-deficient, EPCR-overexpressing and hemophilia A mice were used in the studies.

RESULTS

Administration ofFVIIa reduced LPS-induced vascular leakage in the lung and kidney; the FVIIa-induced barrier protective effect was attenuated in EPCR-deficient mice. The extent of VEGF-induced vascular leakage in the skin was highly dependent on EPCR expression levels. Therapeutic concentrations of FVIIa attenuated VEGF-induced vascular leakage in control mice but not in EPCR-deficient mice.Blockade of FVIIa binding to EPCR with a blocking mAb completely attenuated the FVIIa-induced barrier protective effect. Similarly, administration of protease activated receptor 1 antagonist blocked the FVIIa induced barrier protective effect. Hemophilic mice showed increased vascular permeability, and administration of therapeutic concentrations of FVIIa improved barrier integrity in these mice.

CONCLUSIONS

This is the first study to demonstrate that FVIIa binding to EPCR leads to a barrier protective effect in vivo. This finding may have clinical relevance, as it indicates additional advantages of using FVIIa in treating hemophilic patients.

Both hemophilia health care providers and hemophilia a carriers report that carriers have excessive bleeding

INTRODUCTION

Hemophilia A, the result of reduced factor VIII activity, is an X-linked recessive bleeding disorder. Previous reports of hemophilia A carriers suggest an increased bleeding tendency. Our objective was to determine the attitudes and understanding of the hemophilia A carrier bleeding phenotype, and opinions regarding timing of carrier testing from the perspective of both medical providers and affected patients. Data from this survey were used as preliminary data for an ongoing prospective study.

MATERIALS AND METHODS

An electronic survey was distributed to physicians and nurses employed at Hemophilia Treatment Centers, and hemophilia A carriers who were members of Hemophilia Federation of America. The questions focused on the clinical understanding of bleeding symptoms and management of hemophilia A carriers, and the timing and intensity of carrier testing.

RESULTS

Our survey indicates that 51% (36/51) of providers compared with 78% (36/46) of carriers believe that hemophilia A carriers with normal factor VIII activity have an increased bleeding tendency (P<0.001); 72% (33/36) of hemophilia A carriers report a high frequency of bleeding symptoms. Regarding carrier testing, 72% (50/69) of medical providers recommend testing after 14 years of age, conversely 65% (29/45) of hemophilia A carriers prefer testing to be done before this age (P<0.001).

DISCUSSION

Hemophilia A carriers self-report a higher frequency of bleeding than previously acknowledged, and have a preference for earlier testing to confirm carrier status.

Phase I study of BAY 94-9027, a PEGylated B-domain-deleted recombinant factor VIII with an extended half-life, in subjects with hemophilia A

BACKGROUND

BAY 94-9027 is a B-domain-deleted recombinant factor VIII (rFVIII) with site-specific attachment of poly(ethylene glycol) that has shown an extended half-life in animal models of hemophilia.

OBJECTIVES

To assess the pharmacokinetics and safety of BAY 94-9027 after single and repeated administration in subjects with severe hemophilia A.

PATIENTS/METHODS

This 8-week, prospective, multicenter, open-label, phase I trial was conducted in 14 subjects aged 21–58 years with FVIII of < 1%, ≥ 150 days of exposure to FVIII, and no history of FVIII inhibitors. After a ≥ 3-day washout, subjects received a single dose of sucrose-formulated rFVIII (rFVIII-FS) (cohort 1 [n = 7], 25 IU kg−1; cohort 2 [n = 7], 50 IU kg−1) for a 48-h pharmacokinetic (PK) study. After another ≥ 3-day washout, cohort 1 received twice-weekly BAY 94-9027 at 25 IU kg−1 (16 doses), and cohort 2 received once-weekly BAY 94-9027 at 60 IU kg−1 (nine doses). A 168-h PK study was performed after the first and last BAY 94-9027 doses.

RESULTS

BAY 94-9027 showed equivalent recovery and an improved PK profile vs. rFVIII-FS, with a half-life of ~ 19 h (vs. ~ 13.0 h for rFVIII-FS). BAY 94-9027 was well tolerated, and no immunogenicity was observed.

CONCLUSIONS

This phase I study demonstrates that BAY 94-9027 has an extended half-life in subjects with hemophilia A and, after multiple dosing, was well tolerated with no immunogenicity during the 8-week trial. A phase III study in a larger number of subjects is underway to fully characterize how this prolonged half-life will permit less frequent prophylaxis dosing for patients with hemophilia.

Biochemical and functional characterization of a recombinant monomeric factor VIII-Fc fusion protein

BACKGROUND

Hemophilia A results from a deficiency in factor VIII activity. Current treatment regimens require frequent dosing, owing to the short half-life of FVIII. A recombinant FVIII-Fc fusion protein (rFVIIIFc) was molecularly engineered to increase the half-life of FVIII, by 1.5-2-fold, in several preclinical animal models and humans.

OBJECTIVE

To perform a biochemical and functional in vitro characterization of rFVIIIFc, with existing FVIII products as comparators.

METHODS

 rFVIIIFc was examined by utilizing a series of structural and analytic assays, including mass spectrometry following lysyl endopeptidase or thrombin digestion. rFVIIIFc activity was determined in both one-stage clotting (activated partial thromboplastin time) and chromogenic activity assays, in the context of the FXase complex with purified components, and in both in vitro and ex vivo rotational thromboelastometry (ROTEM) assays performed in whole blood.

RESULTS

 rFVIIIFc contained the predicted primary structure and post-translational modifications, with an FVIII moiety that was similar to other recombinant FVIII products. The von Willebrand factor-binding and specific activity of rFVIIIFc were also found to be similar to those of other recombinant FVIII molecules. Both chromogenic and one-stage assays of rFVIIIFc gave similar results. Ex vivo ROTEM studies demonstrated that circulating rFVIIIFc activity was prolonged in mice with hemophilia A in comparison with B-domain-deleted or full-length FVIII. Clot parameters at early time points were similar to those for FVIII, whereas rFVIIIFc showed prolonged improvement of clot formation.

CONCLUSIONS

 rFVIIIFc maintains normal FVIII interactions with other proteins necessary for its activity, with prolonged in vivo activity, owing to fusion with the Fc region of IgG(1) .

Lentivirus-mediated platelet gene therapy of murine hemophilia A with pre-existing anti-factor VIII immunity

BACKGROUND

The development of inhibitory antibodies, referred to as inhibitors, against exogenous factor VIII in a significant subset of patients with hemophilia A remains a persistent challenge to the efficacy of protein replacement therapy. Our previous studies using the transgenic approach provided proof-of-principle that platelet-specific expression could be successful in treating hemophilia A in the presence of inhibitory antibodies.

OBJECTIVE

To investigate a clinically translatable approach for platelet gene therapy of hemophilia A with pre-existing inhibitors.

METHODS

Platelet FVIII expression in preimmunized FVIII(null) mice was introduced by transplantation of lentivirus-transduced bone marrow or enriched hematopoietic stem cells. FVIII expression was determined with a chromogenic assay. The transgene copy number per cell was quantitated with real-time PCR. Inhibitor titer was measured with the Bethesda assay. Phenotypic correction was assessed by the tail clipping assay and an electrolytically induced venous injury model. Integration sites were analyzed with linear amplification-mediated PCR.

RESULTS

Therapeutic levels of platelet FVIII expression were sustained in the long term without evoking an anti-FVIII memory response in the transduced preimmunized recipients. The tail clip survival test and the electrolytic injury model confirmed that hemostasis was improved in the treated animals. Sequential bone marrow transplants showed sustained platelet FVIII expression resulting in phenotypic correction in preimmunized secondary and tertiary recipients.

CONCLUSIONS

Lentivirus-mediated platelet-specific gene transfer improves hemostasis in mice with hemophilia A with pre-existing inhibitors, indicating that this approach may be a promising strategy for gene therapy of hemophilia A even in the high-risk setting of pre-existing inhibitory antibodies.

A randomized comparison of two prophylaxis regimens and a paired comparison of on-demand and prophylaxis treatments in hemophilia A management

BACKGROUND

Prophylaxis with factor (F)VIII is considered the optimal treatment for managing hemophilia A patients without inhibitors.

OBJECTIVES

To compare the efficacy of two prophylaxis regimens (primary outcome) and of on-demand and prophylaxis treatments (secondary outcome), and to continue the evaluation of immunogenicity and overall safety of the ADVATE Antihemophilic Factor (Recombinant), Plasma/Albumin Free Method (rAHF-PFM).

PATIENTS/METHODS

Previously on-demand-treated patients aged 7-59 years (n = 66) with FVIII levels ≤ 2% received 6 months of on-demand treatment and then were randomized to 12 months of either standard (20-40 IU kg(-1) every other day) or pharmacokinetic (PK)-tailored (20-80 IU kg(-1) every third day) prophylaxis, both regimens intended to maintain FVIII trough levels at or above 1%. Efficacy was evaluated in terms of annualized bleeding rates (ABRs). As subjects were first treated on-demand and then on prophylaxis, statistical comparisons between these treatments were paired.

RESULTS

Twenty-two (33.3%) subjects on prophylaxis experienced no bleeding episodes, whereas none treated on-demand were free from an episode of bleeding. ABRs for the two prophylaxis regimens were comparable, whereas differences between on-demand and either prophylaxis were statistically significant (P < 0.0001): median (interquartile range [IQR]) ABRs were 43.9 (21.9), 1.0 (3.5), 2.0 (6.9) and 1.1 (4.9) during on-demand treatment, standard, PK-tailored and any prophylaxis, respectively. There were no differences in FVIII consumption or adverse event rates between prophylaxis regimens. No subject developed FVIII inhibitors.

CONCLUSIONS

The present study demonstrates comparable safety and effectiveness for two prophylaxis regimens and that prophylaxis significantly reduces bleeding compared with on-demand treatment. PK-tailored prophylaxis offers an alternative to standard prophylaxis for the prevention of bleeding.

Bioengineering of coagulation factor VIII for efficient expression through elimination of a dispensable disulfide loop

BACKGROUND

Heterologous expression of factor VIII (FVIII) is about two to three orders of magnitude lower than similarly sized proteins. Bioengineering strategies aimed at different structural and biochemical attributes of FVIII have been successful in enhancing its expression levels.

OBJECTIVE

Disulfide bonds are vital to the proper folding, secretion and stability of most secretory proteins. In an effort to explore additional targeted bioengineering approaches, the role of disulfide bonds in FVIII secretion and function was probed in this study.

METHODS AND RESULTS

Single and paired cysteine mutants were generated by substituting with serine or glycine residues and analyzed by transient transfection into COS-1 and CHO cells. Seven of the eight disulfide bonds in FVIII were found to be indispensable for proper secretion and function. However, elimination of the disulfide bond formed by C1899 and C1903 within the conserved A3 domain improved the secretion of FVIII. The addition of the C1899G/C1903G mutations to a previously described FVIII variant, 226/N6, with high secretion efficiency increased its secretion by 2.2-fold. Finally, the addition of the A1-domain mutation, F309S, in conjunction with the disulfide mutation had an additive effect, resulting in a net improvement in secretion of between 35 and 45-fold higher than wild-type FVIII in CHO cells.

CONCLUSION

Such combined targeted bioengineering strategies may facilitate more efficient production of recombinant FVIII and contribute toward low-cost factor replacement therapy for hemophilia A.

A case-control study reveals immunoregulatory gene haplotypes that influence inhibitor risk in severe haemophilia A

Several genes that modify risk of factor VIII (FVIII) inhibitors in haemophilia A patients have been identified. Aside from the underlying mutations that cause haemophilia A, inhibitor risk appears to be modified by polymorphisms in various cytokines and immunomodulators including IL10, TNFα and CTLA4. HLA haplotypes have not been strong determinants of inhibitor risk. We sought to confirm previous observations on FVIII inhibitor risk-modifying genes and to test new candidate genes encoding various otherTH1/TH2 cytokines. We also sought to determine whether normal FVIII gene polymorphisms affect inhibitor risk in caucasians. We studied 915 caucasian, severe haemophilia A patients (282 inhibitor cases and 633 non-inhibitor controls). Genes were analysed using 368 tagging single nucleotide polymorphisms starting 20 kb 5' and ending 10 kb 3' of each gene's coding sequence; four other polymorphisms (factor V Leiden & prothrombin 20210 polymorphisms and two in HFE) were also evaluated. Haplotypes that increased inhibitor risk were found in IL10 (OR = 1.33, P = 0.04), IL12 (OR = 1.31, P = 0.04) and IL1α (OR = 2.16, P = 0.034). Protective haplotypes were seen in IL2 (OR =  .69, P = 0.008) and IL1β (OR = 0.75, P = 0.02). One rare haplotype in the FVIII gene increased the risk of inhibitor development by nearly fourfold (OR = 3.8, P = 0.004). We replicate previous findings for IL10; identify new associations with IL1, IL2 and IL12; and identify a rare FVIII haplotype in caucasians that is associated with increased inhibitor risk.

Most factor VIII B domain missense mutations are unlikely to be causative mutations for severe hemophilia A: implications for genotyping

BACKGROUND & OBJECTIVE

 The factor VIII (FVIII) B domain shares very little amino acid homology with other known proteins and is not directly necessary for procoagulant activity. Despite this, missense mutations within the B domain have been reported in patients with hemophilia A. Given that the B domain is dispensable for secretion and function of FVIII, we hypothesized that these mutations should not be causative of hemophilia A in these patients.

METHODS

 Plasmid vectors containing B domain missense mutations that were reported to be associated with moderate/severe hemophilia A (T751S, D826E, V993L, H1047Y, T1353A, N1441K, L1462P, E1579D, A1591S, P1641L and S1669L) were analyzed for their effect on synthesis and secretion compared with FVIII wild-type (WT) following transient transfection into COS-1 and CHO cells in vitro. Further, H1047Y, N1441K and E1579D mutants were expressed in vivo in a hemophilia A mouse model by hydrodynamic tail-vein injection.

RESULTS

 FVIII activity and antigen levels for all mutants expressed into the conditioned media of COS-1 and CHO cells were similar to FVIII WT. Also, plasma expression of these mutants was similar to FVIII WT in hemophilia A mice. An in vivo tail clip bleeding assay also demonstrated that blood loss from hemophilia A mice expressing FVIII WT, H1047Y, N1441K and E1579D was similar.

CONCLUSIONS

 We conclude that most missense mutations within the FVIII B domain would be unlikely to lead to severe hemophilia A and that the majority of such missense mutations represent polymorphisms or non-pathologic mutations.

Factor VIII delivered by haematopoietic stem cell-derived B cells corrects the phenotype of haemophilia A mice

The main impediments to clinical application of haematopoietic stem cell (HSC) gene therapy for treatment of haemophilia A are the bone marrow transplant-related risks and the potential for insertional mutagenesis caused by retroviral vectors. To circumvent these limitations, we have adapted a non-myeloablative conditioning regimen and directed factor VIII (FVIII) protein synthesis to B lineage cells using an insulated lentiviral vector containing an immunoglobulin heavy chain enhancer-promoter. Transplantation of lentiviral vector-modified HSCs resulted in therapeutic levels of FVIII in the circulation of all transplanted mice for the duration of the study (six months). Immunostaining of spleen cells showed that the majority of FVIII was synthesised by B220+ B cells and CD138+ plasma cells. Subsequent challenge with recombinant FVIII elicited at most a minor anti-FVIII antibody response, demonstrating induction of immune hyporesponsiveness. All transplant recipients exhibited clot formation and survived tail clipping, indicating correction of their haemophilic phenotype. Therapeutic levels of FVIII could be transferred to secondary recipients by bone marrow transplantation, confirming gene transfer into long-term repopulating HSCs. Moreover, short-term therapeutic FVIII levels could also be achieved in secondary recipients by adoptive transfer of HSC-derived splenic B cells. Our findings support pursuit of B cell-directed protein delivery as a potential clinical approach to treat haemophilia A and other disorders correctable by systemically distributed proteins.

T-cell responses in two unrelated hemophilia A inhibitor subjects include an epitope at the factor VIII R593C missense site

BACKGROUND

Development of neutralizing anti-factor (F)VIII antibodies ('inhibitors') is a serious clinical problem in hemophilia A. Increased inhibitor risk has been associated with certain FVIII missense substitutions, including R593C in the A2 domain.

OBJECTIVES

The aim of the present study was to identify T-cell epitopes in FVIII and characterize T-cell responses in two unrelated hemophilia A subjects sharing F8-R593C and HLA-DRB1*1101 genotypes. We hypothesized that the hemophilic substitution site coincides with an important T-cell epitope.

PATIENTS/METHODS

The binding affinities of peptides for recombinant HLA-DR proteins were measured and compared with epitope prediction results. CD4+ T cells were stimulated using peptides and stained with fluorescent, peptide-loaded tetramers.

RESULTS

The inhibitor subjects, but not HLA-matched controls, had high-avidity HLA-DRB1*1101-restricted T-cell responses against FVIII(589-608), which contains the hemophilic missense site. Antigen-specific T cells secreted Th1 and Th2 cytokines and proliferated in response to FVIII and FVIII(592-603). FVIII(589-608) bound with physiologically relevant (micromolar) IC(50) values to recombinant DR0101, DR1101 and DR1501 proteins.

CONCLUSIONS

Hemophilia A patients with R593C missense substitutions and these HLA haplotypes had an increased incidence of inhibitors in our cohorts, supporting a paradigm in which presentation of FVIII epitopes containing the wild-type R593 influences inhibitor risk in this hemophilia A sub-population.

In non-severe hemophilia A the risk of inhibitor after intensive factor treatment is greater in older patients: a case-control study

BACKGROUND

 Twenty-five percent of new anti-factor VIII (FVIII) antibodies (inhibitors) that complicate hemophilia A occur in those with mild and moderate disease. Although intensive FVIII treatment has long been considered a risk factor for inhibitor development in those with non-severe disease, its strength of association and the influence of other factors have remained undefined.

OBJECTIVE

 To evaluate risk factors for inhibitor development in patients with non-severe hemophilia A.

METHODS

 Information on clinical and demographic variables and FVIII genotype was collected on 36 subjects with mild or moderate hemophilia A and an inhibitor and 62 controls also with mild or moderate hemophilia A but without an inhibitor.

RESULTS

 Treatment with FVIII for six or more consecutive days during the prior year was more strongly associated with inhibitor development in those ≥30years of age compared with those <30years of age [adjusted odds ratio (OR) 12.62; 95% confidence interval (CI), 2.76-57.81 vs. OR 2.54; 95% CI, 0.61-10.68]. Having previously received <50days of FVIII was also not statistically associated with inhibitor development on univariate or multivariate analysis.

CONCLUSIONS

 These findings suggest that inhibitor development in mild and moderate hemophilia A varies with age, but does not vary significantly with lifetime FVIII exposure days: two features distinct from severe hemophilia A.

Delivery of nucleic acid therapeutics by genetically engineered hematopoietic stem cells

Several populations of adult human stem cells have been identified, but only a few of these are in routine clinical use. The hematopoietic stem cell (HSC) is arguably the most well characterized and the most routinely transplanted adult stem cell. Although details regarding several aspects of this cell's phenotype are not well understood, transplant of HSCs has advanced to become the standard of care for the treatment of a range of monogenic diseases and several types of cancer. It has also proven to be an excellent target for genetic manipulation, and clinical trials have already demonstrated the usefulness of targeting this cell as a means of delivering nucleic acid therapeutics for the treatment of several previously incurable diseases. It is anticipated that additional clinical trials will soon follow, such as genetically engineering HSCs with vectors to treat monogenic diseases such as hemophilia A. In addition to the direct targeting of HSCs, induced pluripotent stem (iPS) cells have the potential to replace virtually any engineered stem cell therapeutic, including HSCs. We now know that for the broad use of genetically modified HSCs for the treatment of non-lethal diseases, e.g. hemophilia A, we must be able to regulate the introduction of nucleic acid sequences into these target cells. We can begin to refine transduction protocols to provide safer approaches to genetically manipulate HSCs and strategies are being developed to improve the overall safety of gene transfer. This review focuses on recent advances in the systemic delivery of nucleic acid therapeutics using genetically modified stem cells, specifically focusing on i) the use of retroviral vectors to genetically modify HSCs, ii) the expression of fVIII from hematopoietic stem cells for the treatment of hemophilia A, and iii) the use of genetically engineered hematopoietic cells generated from iPS cells as treatment for disorders of hematopoiesis.

Comparative pharmacokinetics of plasma- and albumin-free recombinant factor VIII in children and adults: the influence of blood sampling schedule on observed age-related differences and implications for dose tailoring

BACKGROUND

Dose tailoring of coagulation factors requires reliably estimated and reproducible pharmacokinetics (PK) in the individual patient.

OBJECTIVES

To investigate the contribution of both biological and methodological factors to the observed variability of factor VIII (FVIII) PK, with the focus on differences between children and adults, and to examine the implications for dosing.

PATIENTS

Data from 52 1-6-year-old and 100 10-65-year-old patients with hemophilia A (FVIII < or = 2 IU dL(-1)) in three clinical studies were included.

RESULTS

In vivo recovery was lower, weight-adjusted clearance was higher and FVIII half-life was on average shorter in children than in adults. However, a reduced blood sampling schedule for children was estimated to account for up to one half of the total observed differences. Intrapatient variance in PK was smaller than interpatient variance in 10-65-year-olds. Age and ratio of actual to ideal weight only showed weak relationships with PK parameters. Variance in PK caused large variance in the calculated dose required to maintain a target FVIII trough level during prophylactic treatment.

CONCLUSION

Differences in blood sampling schedules should be taken into account when results from different PK studies are compared. However, even with this consideration, PK cannot be predicted from observable patient characteristics but must be determined for the individual. Because the influence of reducing the blood sampling was minor in comparison to the true variance between patients, a reduced blood sampling protocol can be used. Low intrapatient variability supports the use of PK measurements for dose tailoring of FVIII.

Clinical and molecular characterization of a re-established line of sheep exhibiting hemophilia A

BACKGROUND

Large animal models that accurately mimic human hemophilia A (HA) are in great demand for developing and testing novel therapies to treat HA.

OBJECTIVES

To re-establish a line of sheep exhibiting a spontaneous bleeding disorder closely mimicking severe human HA, fully characterize their clinical presentation, and define the molecular basis for disease.

PATIENTS/METHODS

Sequential reproductive manipulations were performed with cryopreserved semen from a deceased affected ram. The resultant animals were examined for hematologic parameters, clinical symptoms, and responsiveness to human FVIII (hFVIII). The full coding region of sheep FVIII mRNA was sequenced to identify the genetic lesion.

RESULTS AND CONCLUSIONS

The combined reproductive technologies yielded 36 carriers and 8 affected animals. The latter had almost non-existent levels of FVIII:C and extremely prolonged aPTT, with otherwise normal hematologic parameters. These animals exhibited bleeding from the umbilical cord, prolonged tail and nail cuticle bleeding time, and multiple episodes of severe spontaneous bleeding, including hemarthroses, muscle hematomas and hematuria, all of which responded to hFVIII. Inhibitors of hFVIII were detected in four treated animals, further establishing the preclinical value of this model. Sequencing identified a premature stop codon and frame-shift in exon 14, providing a molecular explanation for HA. Given the decades of experience using sheep to study both normal physiology and a wide array of diseases and the high homology between human and sheep FVIII, this new model will enable a better understanding of HA and facilitate the development and testing of novel treatments that can directly translate to HA patients.

Effect of route of administration of human recombinant factor VIII on its immunogenicity in Hemophilia A mice

Factor VIII is a multi-domain glycoprotein and is an essential cofactor in the blood coagulation cascade. Its deficiency or dysfunction causes Hemophilia A, a bleeding disorder. Replacement using exogenous recombinant Factor VIII (FVIII) is the first line of therapy for Hemophilia A. Immunogenicity, the development of binding (total) and neutralizing (inhibitory) antibody against administered protein is a clinical complication of the therapy. There are several product related factors such as presence of aggregates, route and frequency of administration and glycosylation have been shown to contribute to immunogenicity. The effect of route of administration of FVIII on antibody development in Hemophilia A is not completely understood. Here we investigated the effect of route of administration (s.c. or i.v.) on immunogenicity in Hemophilia A mice. The total and inhibitory titers were determined using ELISA and modified Bethesda Assay respectively. The results indicated that s.c. is more immunogenic compared to i.v. route in terms of total antibody titer development (binding antibodies) but no significant differences in inhibitory titer levels could be established.