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Objective: To analyze the results of activated partial thromboplastin time (APTT) mixing test in coagulation factor Ⅷ inhibitor-positive hemophilia patients, so as to increase the value of APTT mixing test in the screen of factor Ⅷ inhibitor., Methods: Eighty plasmas samples with different titers of coagulation factor Ⅷ inhibitors had been collected and diluted for routine immediate APTT mixing test and at 37 ℃ 2 hours incubation APTT mixing test. Fifteen samples were selected for immediate and normal temperature incubation for 15 min, 30min, 1 hour, 2 hours and 37 ℃ for 30 min, 1 hour, 2 hours APTT mixing test., Results: The results of APTT mixing test were significantly correlated with the titers of coagulation factor Ⅷ inhibitors. The ROC curve result showed that the best diagnostic cut-off value for 2 hours incubation APTT mixing test at 37 ℃ to determine the presence or absence of coagulation factor Ⅷ inhibitors was 43.8 s (sensitivity and specificity was 85.90% and 100%, respectively), while the best diagnostic cut-off value for distinguishing high-titer and low-titer Ⅷ inhibitors was 52.4 s (sensitivity and specificity was 98.18% and 95.65%, respectively). The critical coagulation factor Ⅷ inhibitor titer that could not be corrected by immediate APTT was 5.14 BU/ml, while that could not be corrected by 37 ℃ 2 hours incubation APTT was 1.31 BU/ml. Paired samples t -test was performed on the APTT mixing test results at different times and temperatures, and the differences were statistically significant ( P < 0.05)., Conclusions: The APTT mixing test can be used as a screening index for coagulation factor Ⅷ inhibitors. APTT mixing test result shows a significant time-temperature dependence with lower titers of coagulation factor Ⅷ inhibitor. Patients with hemophilia who cannot be corrected by immediate APTT mixing test should be alert to the possibility of high titer of coagulation factor Ⅷ.

Background: Coagulation factor VIII (FVIII) and von Willebrand factor (VWF) circulate as a noncovalent complex, but each has its distinct functions. Binding of FVIII to VWF results in a prolongation of FVIII's half-life in circulation and modulates FVIII's immunogenicity during hemophilia therapy. However, the biological effect of FVIII and VWF interaction on VWF homeostasis is not fully understood., Objectives: To determine the effect of FVIII in VWF proteolysis and homeostasis in vivo., Methods: Mouse models, recombinant FVIII infusion, and patients with hemophilia A on a high dose FVIII for immune tolerance induction therapy or emicizumab for bleeding symptoms were included to address this question., Results: An intravenous infusion of a recombinant B-domain less FVIII (BDD-FVIII) (40 and 160 μg/kg) into wild-type mice significantly reduced plasma VWF multimer sizes and its antigen levels; an infusion of a high but not low dose of BDD-FVIII into Adamts13 +/- and Adamts13 -/- mice also significantly reduced the size of VWF multimers. However, plasma levels of VWF antigen remained unchanged following administration of any dose BDD-FVIII into Adamts13 -/- mice, suggesting partial ADAMTS-13 dependency in FVIII-augmented VWF degradation. Moreover, persistent expression of BDD-FVIII at ∼50 to 250 U/dL via AAV8 vector in hemophilia A mice also resulted in a significant reduction of plasma VWF multimer sizes and antigen levels. Finally, the sizes of plasma VWF multimers were significantly reduced in patients with hemophilia A who received a dose of recombinant or plasma-derived FVIII for immune tolerance induction therapy., Conclusion: Our results demonstrate the pivotal role of FVIII as a cofactor regulating VWF proteolysis and homeostasis under various (patho)physiological conditions., Competing Interests: Declaration of competing interests X.L.Z. is a consultant and a member of the advisory boards for Alexion, Apollo, GC Biopharma, Sanofi, Stago, and Takeda. X.L.Z. is also the cofounder of Clotsolution. W.C. holds equity in Ivygen. All other authors have declared no relevant conflict., (Copyright © 2023 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)

Objective To evaluate the performance of myPKFiT,a tool guiding the dosing of antihemophilic factor (recombinant) plasma/albumin-free method (rAHF-PFM),in maintaining the coagulation factor Ⅷ (FⅧ) level above a target threshold at the steady state and estimating the pharmacokinetics (PK) parameters in hemophilia A patients in China. Methods The data of 9 patients with severe hemophilia A in a trial (CTR20140434) assessing the safety and efficacy of rAHF-PFM in the Chinese patients with hemophilia A were analyzed.The myPKFiT was used to predict the adequate dose to maintain a patient's FⅧ level above target threshold at the steady state.Furthermore,the performance of myPKFiT in estimating the pharmacokinetics parameters of individuals was evaluated. Results Twelve combinations of two dosing intervals and six sparse sampling schedules were investigated,and 57%-88% of the patients remained the FⅧ level above the target threshold of 1 U/dl (1%) for at least 80% of the dosing interval.The clearance and time to FⅧ level of 1% obtained from sparse sampling by myPKFiT were similar to those obtained from extensive sampling. Conclusions The myPKFiT can provide adequate dose estimates to maintain the FⅧ level above the target threshold at the steady state in Chinese patients with severe hemophilia A.Moreover,it demonstrates good performance for estimating key pharmacokinetics parameters,including clearance and time to FⅧ level of 1%.

Objective: To evaluate the clinical effects of low- and intermediate-dose factor Ⅷ (F Ⅷ) prophylaxis in Chinese adult patients with severe hemophilia A. Methods: Thirty adult patients with severe hemophilia A who received low- ( n =20) /intermediate-dose ( n =10) F Ⅷ prophylaxis at Nanjing Drum Tower Hospital affiliated with Nanjing University Medical College were included in the study. The annual bleeding rate (ABR), annual joint bleeding rate (AJBR), number of target joints, functional independence score of hemophilia (FISH), quality of life score, and health status score (SF-36) before and after preventive treatment were retrospectively analyzed and compared. Results: The median follow-up was 48 months. Compared with on-demand treatment, low- and intermediate-dose prophylaxis significantly reduced ABR, AJBR, and the number of target joints ( P <0.05) ; the improvement in the intermediate-dose prophylaxis group was better than that in the low-dose prophylaxis group ( P <0.05). Compared with on-demand treatment, the FISH score, quality of life score, and SF-36 score significantly improved in both groups ( P <0.05), but there was no significant difference between the two groups ( P >0.05) . Conclusion: In Chinese adults with severe hemophilia A, low- and intermediate-dose prophylaxis can significantly reduce bleeding frequency, delay the progression of joint lesions, and improve the quality of life of patients as compared with on-demand treatment. The improvement in clinical bleeding was better with intermediate-dose prophylaxis than low-dose prophylaxis.

The splenic endothelial Weibel-palade bodies are one of the most important candidate organelles to release von Willebrand factor upon stimulation with desmopressin. However, the presence of functional desmopressin-specific receptor has not yet been demonstrated on endothelial cells. Experimental evidences are in favour of an indirect pro-haemostatic effect of desmopressin, but the exact mediator and its cellular origin are largely elusive. Here, we report partially hampered desmopressin response in a splenectomised severe haemophilia A/Beta Thalassemia patient without any genetic variant relevant to his incomplete desmopressin response. To further investigate the role of the spleen in this phenomenon, the release of VWF from desmopressin-treated human splenic endothelial cells was assessed in vitro. As a result, desmopressin induced the release of VWF from endothelial cells when the cells were co-cultured with non-classical (CD14 dim /CD16 ++ ), but not other subtypes of monocytes or PBMCs. This in vitro study which resembles close proximity of endothelial cells of sinusoids to monocyte reservoir reside in parenchyma of subcapsular red pulp of the spleen sheds a light upon the role of this highly vascularized VWF-producing organ in driving indirect effect of desmopressin., (© 2022 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

Introduction: Despite receiving standard half-life (SHL) factor VIII (FVIII) concentrates prophylaxis, some severe haemophilia A (HA) patients still encounter spontaneous breakthrough bleeding. Individualized pharmacokinetic (PK)-guided dosing of extended half-life (EHL) FVIII concentrates may reduce their bleeding events., Aim: To compare clinical outcomes before and after switching low-dose prophylaxis using weight-based SHL FVIII to PK-guided EHL FVIII concentrates, taking into consideration of a trough FVIII activity at 1 IU/dl above natural baseline., Methods: In this single-centre prospective cohort, Thai severe or moderate HA (FVIII activity ≤3 IU/dl) patients receiving low-dose weight-based SHL FVIII prophylaxis were enrolled. After a 3-day wash-out period, participants underwent low-dose EHL FVIII prophylaxis with PK-based adjustment (myPKFiT ® ) for 6 months. The annualized bleeding rates (ABR), the annualized joint bleeding rates (AJBR), the haemophilia-specific quality-of-life (Haemo-QoL or Haemo-QoL-A) scores, the Hemophilia Joint Health Scores (HJHS) and the annualized FVIII consumption were compared between the two prophylactic periods., Results: Of 15 eligible subjects (mean age 18.7 ± 6.7 years), ABR, AJBR and HJHS were significantly reduced (mean differences of -11.1 ± 4.9 bleeds/year, -10.4 ± 5.2 joint bleeds/year and -5.1 ± 1.5 marks, respectively; P < .001 for all comparisons) after switching regimen. The quality-of-life scores had also improved (P = .001). Nonetheless, FVIII consumption tended to increase despite no statistical significance (means of 1240.9 ± 531.3 SHL FVIII IU/kg/year versus 1591.7 ± 438.9 EHL FVIII IU/kg/year; P = .05)., Conclusions: This is the first low-dose, PK-guided, EHL FVIII prophylaxis clinical study in Thailand. Benefits and practicability of this personalized regimen may support the implementation of regular FVIII prophylaxis in developing countries with budget constraints., Clinicaltrials: gov NCT05281185., (© 2022 John Wiley & Sons Ltd.)

Acquired hemophilia A (AHA) is a rare autoimmune bleeding disorder due to the presence of neutralizing autoantibodies directed against the coagulation factor VIII (FVIII). The reference method to detect and quantify anti-FVIII antibodies is the Bethesda assay (BA), but it presents some limitations such as a lack of sensitivity for low titers of inhibitor and the need for experienced laboratory. A commercially available ELISA detecting anti-FVIII antibodies has demonstrated excellent sensitivity and specificity. The aim of our study was to assess the performance of this ELISA for the detection of anti-FVIII IgG in AHA patients during the follow-up. In total, 11 acquired hemophilia A patients were recruited, and anti-FVIII antibody levels were monitored by BA and ELISA. Anti-FVIII IgG ELISA showed 100% sensitivity and 100% specificity, and it correlated with the BA. Discrepancies observed in 13.3% of cases were consistent with patients' biological evolution. All these data suggest the possible use of anti-FVIII IgG ELISA for both diagnosis and follow-up of AHA patients., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Aim: To determine if emicizumab was channeled to clinically complex people with hemophilia A upon approval. Methods: Claims data (16 November 2017, through 31 December 2019) from US-based insurance databases were analyzed to compare the clinical complexity of people with hemophilia A initiating emicizumab with matched individuals receiving factor VIII (FVIII) episodically or prophylactically. People with hemophilia A with evidence of previous bypassing agent use (indicating FVIII inhibitors) were excluded. Outcomes included bleeding events, arthropathy, pain, comorbidities and healthcare costs. Results: A larger proportion of emicizumab users had bleeding events, comorbidities and arthropathy and greater healthcare costs in the year prior to starting emicizumab compared with FVIII users. Conclusion: Claims-based data limitations prevent an absolute conclusion. Nevertheless, emicizumab users appear more clinically complex than FVIII users, suggesting post-approval channeling.

In recent decades, the use of adult multipotent stem cells has paved the way for the identification of new therapeutic approaches for the treatment of monogenic diseases such as Haemophilia A. Being already studied for regenerative purposes, adipose-derived mesenchymal stem cells (Ad-MSCs) are still poorly considered for Haemophilia A cell therapy and their capacity to produce coagulation factor VIII (FVIII) after proper stimulation and without resorting to gene transfection. In this work, Ad-MSCs were in vitro conditioned towards the endothelial lineage, considered to be responsible for coagulation factor production. The cells were cultured in an inductive medium enriched with endothelial growth factors for up to 21 days. In addition to significantly responding to the chemotactic endothelial stimuli, the cell populations started to form capillary-like structures and up-regulated the expression of specific endothelial markers (CD34, PDGFRα, VEGFR2, VE-cadherin, CD31, and vWF). A dot blot protein study detected the presence of FVIII in culture media collected from both unstimulated and stimulated Ad-MSCs. Remarkably, the activated partial thromboplastin time test demonstrated that the clot formation was accelerated, and FVIII activity was enhanced when FVIII deficient plasma was mixed with culture media from the untreated/stimulated Ad-MSCs. Overall, the collected evidence supported a possible Ad-MSC contribution to HA correction via specific stimulation by the endothelial microenvironment and without any need for gene transfection.

Coagulation factor IX (FIX) is a vitamin K dependent protein and its deficiency causes hemophilia B, an X-linked recessive bleeding disorder. More than 1000 mutations in the F9 gene have been identified in hemophilia B patients. Here, we systematically summarize the structural and functional characteristics of FIX and the pathogenic mechanisms of the mutations that have been identified to date. The mechanisms of FIX deficiency are diverse in these mutations. Deletions, insertions, duplications, and indels generally lead to severe hemophilia B. Those in the exon regions generate either frame shift or inframe mutations, and those in the introns usually cause aberrant splicing. Regarding point mutations, the bleeding phenotypes vary from severe to mild in hemophilia B patients. Generally speaking, point mutations in the F9 promoter region result in hemophilia B Leyden, and those in the introns cause aberrant splicing. Point mutations in the coding sequence can be missense, nonsense, or silent mutations. Nonsense mutations generate truncated FIX that usually loses function, causing severe hemophilia B. Silent mutations may lead to aberrant splicing or affect FIX translation. The mechanisms of missense mutation, however, have not been fully understood. They lead to FIX deficiency, often by affecting FIX's translation, protein folding, protein stability, posttranslational modifications, activation to FIXa, or the ability to form functional Xase complex. Understanding the molecular mechanisms of FIX deficiency will provide significant insight for patient diagnosis and treatment.

Background: We have recently reported on a recombinant von Willebrand factor (VWF) D'D3 albumin fusion protein (rD'D3-FP) developed to extend the half-life of coagulation factor VIII (FVIII) for the treatment of hemophilia A. Based on predictive modelling presented in this study, we hypothesized that modifying rD'D3-FP to improve FVIII interaction would reduce exchange with endogenous VWF and provide additional FVIII half-life benefit., Objectives: The aim of this study was to identify novel rD'D3-FP variants with enhanced therapeutic efficacy in extending FVIII half-life., Methods: Through both directed mutagenesis and random mutagenesis using a novel mammalian display platform, we identified novel rD'D3-FP variants with increased affinity for FVIII (rVIII-SingleChain) under both neutral and acidic conditions and assessed their ability to extend FVIII half-life in vitro and in vivo., Results: In rat preclinical studies, rD'D3-FP variants with increased affinity for FVIII displayed enhanced potency, with reduced dose levels required to achieve equivalent rVIII-SingleChain half-life extension. In cell-based imaging studies in vitro, we also demonstrated reduced dissociation of rVIII-SingleChain from the rD'D3-FP variants within acidic endosomes and more efficient co-recycling of the rD'D3-FP/rVIII-SingleChain complex via the FcRn recycling system., Conclusions: In summary, at potential clinical doses, the rD'D3-FP variants provide marked benefits with respect to dose levels and half-life extension of co-administered FVIII, supporting their development for use in the treatment of hemophilia A., (© 2021 International Society on Thrombosis and Haemostasis.)

Aims: Population pharmacokinetic (PK) models are increasingly applied to perform individualized dosing of factor VIII (FVIII) concentrates in haemophilia A patients. To guarantee accurate performance of a population PK model in dose individualization, validation studies are of importance. However, external validation of population PK models requires independent data sets and is, therefore, seldomly performed. Therefore, this study aimed to validate a previously published population PK model for FVIII concentrates administrated perioperatively., Methods: A previously published population PK model for FVIII concentrate during surgery was validated using independent data from 87 children with severe haemophilia A with a median (range) age of 2.6 years (0.03-15.2) and body weight of 14 kg (4-57). First, the predictive performance of the previous model was evaluated with MAP Bayesian analysis using NONMEM v7.4. Subsequently, the model parameters were (re)estimated using a combined dataset consisting of the previous modelling data and the data available for the external validation., Results: The previous model underpredicted the measured FVIII levels with a median of 0.17 IU mL -1 . Combining the new, independent and original data, a dataset comprising 206 patients with a mean age of 7.8 years (0.03-77.6) and body weight of 30 kg (4-111) was obtained. Population PK modelling provided estimates for CL, V1, V2, and Q: 171 mL h -1  68 kg -1 , 2930 mL 68 kg -1 , 1810 mL 68 kg -1 , and 172 mL h -1  68 kg -1 , respectively. This model adequately described all collected FVIII levels, with a slight median overprediction of 0.02 IU mL -1 ., Conclusions: This study emphasizes the importance of external validation of population PK models using real-life data., (© 2021 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Background: The coagulation factors (F)V and VIII are homologous proteins that support hemostasis through their regulation of FX activity. Hemophilia A (HA) patients have reduced FVIII activity and a prolonged bleeding time that is corrected through the administration of exogenous FVIII. Around one-third of severe HA patients develop FVIII neutralizing antibodies, known as "inhibitors," which neutralize FVIII activity and preclude them from further FVIII therapy., Objectives: We hypothesized that, based on the degree of homology between FV and FVIII (~40%), FVIII-neutralizing antibodies could cross react with FV. To test this hypothesis, a panel of recombinant, patient-derived, FVIII-neutralizing antibodies were screened for cross-reactivity against FV., Methods: Factor V and FVIII activity was measured using one-stage clotting assays; structural analysis was carried out using a structural approach., Results: We detected FV neutralizing activity with the anti-FVIII A2 domain antibody NB11B2. Because this antibody was derived from an HA inhibitor patient, FV-neutralizing activity was then evaluated in a number of HA inhibitor patient plasma samples; nine alloimmune samples had FV-neutralizing activity whereas no FV neutralizing activity was found in the two autoimmune samples available. We next examined the degree of surface homology between FV and FVIII and found that structural similarity could explain the cross reactivity of the anti-A2 antibody and likely accounts for the cross reactivity we observed in patient samples., Conclusions: Although this novel observation is of interest, further work will be needed to determine whether FV neutralization in HA patient samples contributes to their bleeding diathesis., (© 2021 Crown copyright. Journal of Thrombosis and Haemostasis published by Wiley Periodicals LLC on behalf of International Society on Thrombosis and Haemostasis. This article is published with the permission of the Controller of HMSO and the Queen‘s Printer for Scotland.)

Human artificial chromosomes (HACs), including the de novo synthesized alphoid tetO -HAC, are a powerful tool for introducing genes of interest into eukaryotic cells. HACs are mitotically stable, non-integrative episomal units that have a large transgene insertion capacity and allow efficient and stable transgene expression. Previously, we have shown that the alphoid tetO -HAC vector does not interfere with the pluripotent state and provides stable transgene expression in human induced pluripotent cells (iPSCs) and mouse embryonic stem cells (ESCs). In this study, we have elaborated on a mouse model of ex vivo iPSC- and HAC-based treatment of hemophilia A monogenic disease. iPSCs were developed from FVIII Y/- mutant mice fibroblasts and FVIII cDNA, driven by a ubiquitous promoter, was introduced into the alphoid tetO -HAC in hamster CHO cells. Subsequently, the therapeutic alphoid tetO -HAC-FVIII was transferred into the FVIII Y/- iPSCs via the retro-microcell-mediated chromosome transfer method. The therapeutic HAC was maintained as an episomal non-integrative vector in the mouse iPSCs, showing a constitutive FVIII expression. This study is the first step towards treatment development for hemophilia A monogenic disease with the use of a new generation of the synthetic chromosome vector-the alphoid tetO -HAC.

Background/objective: Hemophilia A is a genetic disorder through which patients suffer from recurrent bleeding. This can be caused by a defect in human plasma coagulation factor VIII. High incidence of FVIII inhibitors in some severe hemophilia A patients after FVIII therapy is a considerable complication. Determination of good predictive factors can improve the safety of this treatment. HLA-II have been shown as a predictive element for inhibitor development. The goal of this study is to determine the association between HLA-DRB1*15:03, HLA-DRB1*11 and HLA-DRB1*01:01 alleles and FVIII inhibitors in severe hemophilia A patients in Iran., Materials/methods: HLA-DRB1 genotyping was performed using Multiplex sequences Specific Primers (PCR-SSP) in two groups of severe hemophilia A patients comprising 51 and 50 individuals with and without FVIII inhibitors respectively. The levels of inhibitor were determined through Nijmegen-modified Bethesda assay. HLA-DRB1 allele frequencies were compared between groups by using multiple logistic regression models., Results: HLA-DRB1*01:01 allele frequency was significantly higher in patients without inhibitor OR adj : 2.7 (95%CI: 1.08, 6.97; P = 0.034). There wasn't any statistically significant difference in HLA-DRB1*11 allele frequency between groups OR adj : 0.7 (95%CI: 0.27, 1.82; P = 0.47). There was no connection between HLA-DRB1*15:03 and inhibitor development OR adj : 0.94 (95%CI: 0.38, 2.35; P = 0.94)., Conclusion: An association between HLA-DRB1*01:01 and paucity of FVIII inhibitor showed that this allele has probably a protective effect in severe hemophilia A patients in Iran. Determination of the predictive and protective alleles are beneficial in pre-treatment activities and decrease the risk of unsuccessful therapy with FVIII in each population., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Hemophilia A is an X-linked bleeding disorder caused by defects in the gene encoding factor VIII (FVIII). Routine prophylaxis with exogenous FVIII requires frequent intravenous injections. One of the most challenging issues in the treatment of hemophilia A is the development of alloantibodies against infused FVIII. Presence of inhibitors results in an ineffective factor replacement therapy and increases the risk of morbidity and mortality in these patients. Therefore, there is growing interest in the development of new strategies for the prophylaxis and prevention of bleeding in patients with hemophilia to circumvent these drawbacks. Emicizumab (ACE-910; Roche, Genentech and Chugai Pharmaceutical) is a recombinant humanized bispecific antibody that restores the function of missing FVIII by bridging activated FIX and FX, simulating the cofactor function of FVIII., (Copyright 2018 Clarivate Analytics.)

Acquired hemophilia A (AHA), which is caused by autoantibodies against coagulation factor VIII (FVIII) is a rare, life-threatening bleeding disorder, the incidence of which appears to be increasing in Japan as the population ages. However, the clinical characteristics, treatment, and outcomes of AHA remain difficult to establish due to the rarity of this disease. We retrospectively analyzed data from 25 patients (median age 73 years; range 24-92 years; male n = 15) diagnosed with AHA between 1999 and 2015 at Gunma University Hospital. We identified autoimmune diseases and malignancy as underlying conditions in four and three patients, respectively. Factor VIII activity was significantly decreased in all patients (median 2.0%; range <1.0-8.0) by FVIII inhibitor (median 47.0 BU/mL; range 2.0-1010). Among 71 bleeding events, subcutaneous or intramuscular hemorrhage was the most prevalent. Seventeen patients required bypassing agents. Twenty-two (91.7%) of 24 patients treated with immunosuppressive agents achieved complete response (CR) during a median of 57.5 days (range 19-714 days). Although three patients (12%) relapsed and seven (28%) died of infection, none of the deaths were related to bleeding. Although most of our patients achieved CR after immunosuppressive therapy, the rate of infection-related mortality was unsatisfactorily high.

The paper describes 4 clinical cases of thrombotic events (pulmonary embolism, deep vein thrombophlebitis, acute myocardial infarction, ischemic stroke) that have occurred in patients with hemophilia. It discusses the possible causes of their development and methods for their prevention and treatment. Controlled natural hypocoagulation, in which the dose of an administered deficient factor decreases to such an extent that in order to maintain the safe level of hypocoagulation (plasma factor activity is 15-20%; activated partial thromboplastin time is 1.5-2 times normal values), is proposed as one of the treatment options.

Introduction: Immune tolerance induction (ITI) is a standard intervention to eradicate inhibitors in haemophilic patients. However, information on the long-term condition of patients who eradicated the inhibitor totally or partially after ITI is scarce., Aim: To perform a long-term follow-up to describe the status of patients reported as ITI success in the G-ITI study., Methods: This was an international, multicentre, observational, retrospective study of the 57 haemophilic patients who were reported as ITI success in the G-ITI study. Demographics and post-ITI clinical data recorded until January 2015 were extracted from the medical records. A descriptive analysis was undertaken., Results: Forty-four patients were evaluable. Post-ITI follow-up was 9.1 years in average. Thirty-seven target joints were affected in 21 patients; 38 patients presented bleeding with a mean of 1.0 ± 1.2 episodes year -1 , most of them (271/330) treated with Fanhdi ® (Grifols). Around half of the patients underwent at least one surgical procedure. Most venous access complications were of expected nature, requiring hospital stay in practically all cases. Fanhdi was used in 42 patients as the regular haemophilia treatment after ITI, mainly prophylactically. Three patients (6.8%) who were being treated with Fanhdi (prophylaxis), Kogenate (prophylaxis) and Emoclot (on demand), respectively, showed inhibitor relapse (at 29, 53 and 13 months after ITI, with 0.9, 3.65 and 12.5 BU respectively). All of them were successfully tolerized after rescue ITI., Conclusion: After ITI success, all patients continued with regular successful FVIII treatment for haemophilia for more than 9 years. The few inhibitor relapses were successfully overcome after rescue ITI., (© 2016 The Authors. Haemophilia Published by John Wiley & Sons Ltd.)

Background: Prophylactic factor replacement, which prevents hemarthroses and thereby reduces the musculoskeletal disease burden in children with hemophilia A, requires frequent intravenous infusions (three to four times weekly)., Objective: Kids A-LONG was a phase 3 open-label study evaluating the safety, efficacy and pharmacokinetics of a longer-acting factor, recombinant factor VIII Fc fusion protein (rFVIIIFc), in previously treated children with severe hemophilia A (endogenous FVIII level of < 1 IU dL(-1) [< 1%])., Methods: The study enrolled 71 subjects. The starting rFVIIIFc regimen was twice-weekly prophylaxis (Day 1, 25 IU kg(-1) ; Day 4, 50 IU kg(-1) ); dose (≤ 80 IU kg(-1) ) and dosing interval (≥ 2 days) were adjusted as needed. A subset of subjects had sequential pharmacokinetic evaluations of FVIII and rFVIIIFc. The primary endpoint was development of inhibitors (neutralizing antibodies). Secondary endpoints included pharmacokinetics, annualized bleeding rate (ABR), and number of infusions required to control a bleed., Results: No subject developed an inhibitor to rFVIIIFc. Adverse events were typical of a pediatric hemophilic population. The rFVIIIFc half-life was prolonged relative to that of FVIII, consistent with observations in adults and adolescents. The median ABR was 1.96 overall, and 0.00 for spontaneous bleeds; 46.4% of subjects reported no bleeding episodes on study. Ninety-three per cent of bleeding episodes were controlled with one to two infusions. The median average weekly rFVIIIFc prophylactic dose was 88.11 IU kg(-1) . At study end, 62 of 69 subjects (90%) were infusing twice weekly. Among subjects who had been previously receiving FVIII prophylaxis, 74% reduced their dosing frequency with rFVIIIFc., Conclusion: Twice-weekly infusions with rFVIIIFc were well tolerated and yielded low bleeding rates in children with severe hemophilia A., (© 2015 The Authors. Journal of Thrombosis and Haemostasis published by Wiley Periodicals, Inc. on behalf of International Society on Thrombosis and Haemostasis.)

Mice treated with anthrax lethal toxin (LT) exhibit hemorrhage caused by unknown mechanisms. Moreover, LT treatment in mice induced liver damage. In this study, we hypothesized that a suppressed coagulation function may be associated with liver damage, because the liver is the major producing source of coagulation factors. The hepatic expression of coagulant factors and the survival rates were analyzed after cultured cells or mice were exposed to LT. In agreement with our hypothesis, LT induces cytotoxicity against hepatic cells in vitro. In addition, suppressed expression of coagulation factor VIII (FVIII) in the liver is associated with a prolonged plasma clotting time in LT-treated mice, suggesting a suppressive role of LT in coagulation. Accordingly, we further hypothesized that a loss-of-function approach involving treatments of an anticoagulant should exacerbate LT-induced abnormalities, whereas a gain-of-function approach involving injections of recombinant FVIII to complement the coagulation deficiency should ameliorate the pathogenesis. As expected, a sublethal dose of LT caused mortality in the mice that were non-lethally pretreated with an anticoagulant (warfarin). By contrast, treatments of recombinant FVIII reduced the mortality from a lethal dose of LT in mice. Our results indicated that LT-induced deficiency of FVIII is involved in LT-mediated pathogenesis. Using recombinant FVIII to correct the coagulant defect may enable developing a new strategy to treat anthrax.

Inhibitor formation is among the most serious complications of hemophilia treatment. With the US FDA licensure of the novel long-lasting recombinant factor VIII (FVIII) Fc fusion protein, Eloctate, which prolongs FVIII half-life, we propose an innovative approach to prevent inhibitor formation. In this paper, we describe a multicenter, Phase II, single-arm, 48-week trial, the INHIBIT trial, to determine if Eloctate, begun before a bleed and continued as once weekly prophylaxis, will reduce inhibitor formation in children with hemophilia A. We hypothesize that avoiding 'danger,' that is, immune activation by a bleed at first factor exposure and prolonging FVIII half-life will prevent inhibitors and promote FVIII-specific T-cell tolerance. If successful, this approach will suggest a new paradigm in clinical practice.

Background: Immune responses to therapeutic factor VIII remain a major problem, affecting 30% of patients with severe hemophilia A. The primary factors that drive immune responses in these patients remain elusive. There have been conflicting reports on a role of coagulation (or thrombin) in anti-FVIII immune responses., Objective: To assess the importance of coagulation-associated processes for the onset of the anti-FVIII immune response., Methods: Using FVIII-deficient mice, we compared the immunogenicity of recombinant FVIII or the inactive FVIII(V) (634M) mutant. In parallel, the involvement of tissue factor (TF) activity in the anti-FVIII immune response was investigated upon injection of a neutralizing anti-TF antibody or by the use of chimeric mice that lack TF expression in myeloid cells. The development of the anti-FVIII immune response was also monitored after treatment with warfarin., Results: The kinetics of the development of antibody responses to FVIII(V) (634M) were indistinguishable from those of wild-type FVIII. Inhibition of TF activity did not modulate immune responses to exogenous FVIII. Additionally, global inhibition of coagulation with warfarin failed to reduce the anti-FVIII immune response., Conclusions: Thrombin generation or coagulation-associated processes do not modulate the anti-FVIII antibody response in mouse model of severe hemophilia A., (© 2014 International Society on Thrombosis and Haemostasis.)

Most studies on immune tolerance induction (ITI) therapy in haemophilia A patients are focused on primary ITI in children. Here we report on the ITI outcome in a large retrospective cohort, including adults and patients with rescue ITI, treated with a pdFVIII/VWF concentrate. Retrospective data from haemophilic patients (FVIII< 2%) with inhibitors from 22 centres in Spain, Italy and Germany, who underwent primary or rescue ITI with pdFVIII/VWF concentrate, were collected. Complete success (CS), partial success (PS) and failure were defined based on the criteria of the consensus recommendations of the 2006 International ITI Workshop. A total of 41 cases of primary ITI (32 children and 9 adults) and 19 cases of rescue ITI (17 children and 2 adults) were evaluated. Success (CS+PS) rate of 87% was achieved in primary ITI and 74% in the higher risk profile of rescue ITI. Eight of nine (85%) patients with poorest prognosis (three or more of the known risk factors of poor response to ITI) achieved success (CS+PS). CS of 100% was observed in eight primary ITI patients with titre at start of ITI ≤2.5 BU and inhibitor peak ≤25 BU. The favourable response rates in primary and rescue ITI in children and in adult patients, even in the presence of poor prognostic factors, should be encouraged for broadening the indication of immune tolerance therapy in haemophilia A patients with inhibitors., (© 2013 John Wiley & Sons Ltd.)

A fundamental goal of medical genetics is the accurate prediction of genotype-phenotype correlations. As an approach to develop more accurate in silico tools for prediction of disease-causing mutations of structural proteins, we present a gene- and disease-specific prediction tool based on a large systematic analysis of missense mutations from hemophilia A (HA) patients. Our HA-specific prediction tool, HApredictor, showed disease prediction accuracy comparable to other publicly available prediction software. In contrast to those methods, its performance is not limited to non-synonymous mutations. Given the role of synonymous mutations in disease and drug codon optimization, we propose that utilizing a gene- and disease-specific method can be highly useful to make functional predictions possible even for synonymous mutations. Incorporating computational metrics at both nucleotide and amino acid levels along with multiple protein sequence/structure alignment significantly improved the predictive performance of our tool. HApredictor is freely available for download at http://www.ncbi.nlm.nih.gov/CBBresearch/Przytycka/HA&#95;Predict/index.htm., (© 2013. Published by Elsevier Ltd. All rights reserved.)

Background: Recombinant activated factor VII (rFVIIa, NovoSeven) was introduced in 1996 for the treatment of hemophilic patients with antibodies against coagulation factor VIII or IX., Objective: To review the evidence supporting the use of rFVIIa for the treatment of patients with congenital bleeding disorders., Patients and Methods: English-language databases were searched in September 2009 for reports of randomized controlled trials (RCTs) evaluating the ability of rFVIIa to restore hemostasis in patients with congenital bleeding disorders., Results: Eight RCTs involving 256 hemophilic patients with antibodies against coagulation factors, also known as inhibitors, were identified. The evidence supporting the use of rFVIIa in these patients was weak with regard to dose, clinical setting, mode of administration, efficacy, and adverse events, given the limited sample size of each RCT and the heterogeneity of the studies., Conclusion: The authors suggest that rFVIIa therapy in hemophilic patients with inhibitors should be based on the individual's ability to generate thrombin and form a clot, and not on the patient's weight alone. Therefore, assays for thrombin generation, such as whole-blood thromboelastography, have the potential to significantly improve the treatment of these patients.

Blood disorders, such as sickle cell disease, and other clinical conditions are often accompanied by intravascular hemolytic events along with the development of severe coagulopathies. Hemolysis, in turn, leads to the accumulation of Fe(II/III)-protoporphyrin IX (heme) in the intravascular compartment, which can trigger a variety of proinflammatory and prothrombotic reactions. As such, heme binding to the blood coagulation proteins factor VIII (FVIII), fibrinogen, and activated protein C with functional consequences has been demonstrated earlier. We herein present an in-depth characterization of the FVIII-heme interaction at the molecular level and its (patho-)physiological relevance through the application of biochemical, biophysical, structural biology, bioinformatic, and diagnostic tools. FVIII has a great heme-binding capacity with seven heme molecules associating with the protein. The respective binding sites were identified by investigating heme binding to FVIII-derived peptides in combination with molecular docking and dynamic simulation studies of the complex as well as cryo-electron microscopy, revealing three high-affinity and four moderate heme-binding motifs (HBMs). Furthermore, the relevance of the FVIII-heme complex formation was characterized in physiologically relevant assay systems, revealing a ~ 50 % inhibition of the FVIII cofactor activity even in the protein-rich environment of blood plasma. Our study provides not only novel molecular insights into the FVIII-heme interaction and its physiological relevance, but also strongly suggests the reduction of the intrinsic pathway and the accentuation of the final clotting step (by, for example, fibrinogen crosslinking) in hemolytic conditions as well as a future perspective in the context of FVIII substitution therapy of hemorrhagic events in hemophilia A patients. [Display omitted] • Coagulation factor VIII (FVIII) binds rapidly up to seven heme molecules. • Heme binds to sequence stretches of functional relevance for FVIII. • Labile heme causes distinct structural changes in FVIII, including increased flexibility. • FVIII cofactor function is significantly impaired by heme in blood plasma. [ABSTRACT FROM AUTHOR]

Hemophilia A is an X-chromosome-linked recessive genetic disease that lacks coagulation factor Ⅷ (Factor Ⅷ, FⅧ) and is clinically manifested as spontaneous or excessive bleeding after injury.The current main treatment for hemophilia A is alternative infusion of FⅧ, but the fixed infusion mode is still used for the dosage and frequency of infusion, which cannot achieve the optimal curative effect under the principle of individualized treatment.Among the factors that affect the efficacy of FⅧ replacement therapy, the difference in the pharmacokinetics (PK) of FⅧ products by individuals is an important factor.The clinical understanding of individualized FⅧ replacement therapy under the guidance of PK is not sufficient.Therefore, this article reviews the PK characteristics, analysis models, clinical application scenarios and specific treatment plan formulation of FⅧ.

Background The efficacy, safety, and immunogenicity of each of Octapharma's factor VIII (FVIII) products, Nuwiq, octanate, and wilate, have been investigated in previously untreated patients (PUPs) with severe hemophilia A in prospective clinical trials. The aim of the Protect-NOW study is to evaluate the effectiveness, safety, and utilization patterns of Nuwiq, octanate, and wilate in PUPs and minimally treated patients (MTPs;

Acquired hemophilia A (AHA) is a rare bleeding disorder, especially in adolescents and young adults (AYAs) attributable to the development of autoantibodies against coagulation factor VIII (FVIII). AHA diagnosis is difficult; patients lack any history of coagulopathy. We report here on an AYA with AHA who responded well to treatment. A 19-year-old woman visited our hospital with painful swelling of the right lower leg. She had no past or familial history of a bleeding disorder. The initial laboratory data revealed a prolonged activated partial thromboplastin time and an uncorrected mixing test result. The FVIII activity was below 1% and the FVIII antibody level 22.4 Bethesda units. She was diagnosed with AHA and treated with recombinant activated coagulation factor VII, activated prothrombin complex concentrates and an oral steroid. After 9 months, FVIII antibody level was negative and the FVIII activity was normalized. AHA is very rare especially in AYAs, but physicians must be suspicious about the disorder and plan specialized coagulation tests to diagnose the disease. An early diagnosis of acquired bleeding disorders should be done for initiating the adequate treatment immediately by both controlling the acute bleeding episode and eliminating FVIII antibodies.

According to the World Federation of Hemophilia (WFH), there are currently about 400 thousand patients with hemophilia in the world. Severe clinical manifestations of the disease associated with a genetically determined deficiency of blood clotting factor activity require continuous replacement therapy with blood clotting medicines. Long-term use of protein-based medicines often leads to the formation of specific antibodies, which causes a decrease in or loss of efficacy of the medicine or results in severe adverse reactions, including anaphylaxis. Therefore, it is important to search for new optimal approaches to hemophilia treatment, which requires the development of new blood clotting factor products, improvement of the production technology for already authorised products, as well as the use of non-factor products. The aim of the study was to present the results of the analysis of key issues related to the development and characteristics of plasma-derived and recombinant factor VIII products, new approaches to hemophilia A treatment, including the use of non-factor products. The review summarises current data on the etiology, clinical manifestations, and complications of hemophilia A treatment. It provides information on the blood clotting factor products (plasma-derived and recombinant) used as replacement therapy. It also provides information on advanced research projects for the development of new biotechnology-derived products which have good prospects of successful clinical use.

Osteoporosis is a clinically prevalent comorbidity in patients with hemophilia. A preventive effect of kefir peptides (KPs) on postmenopausal osteoporosis has been proved. The aim of this study was to evaluate the therapeutic effect of KPs for the treatment of osteoporosis in coagulation factor VIII (FVIII) gene knockout mice (F8KO), a model of hemophilia A. In this study, male F8KO mice at 20 weeks of age were orally administered different doses of KPs for 8 weeks. The therapeutic effects of KPs were shown in the femoral trabeculae and the 4th lumbar vertebrae, which increased the trabecular bone mineral density (BMD), bone volume (Tb.BV/TV), and trabecular number (Tb.N) and decreased the trabecular separation (Tb.Sp), and they were also observed in the femoral cortical bones, in which the mechanical properties were enhanced in a dose-dependent manner. Characterization of receptor activator of nuclear factor κB ligand (RANKL), osteoprotegerin (OPG), and interleukin 6 (IL-6) demonstrated that the serum RANKL/OPG ratio and IL-6 levels were significantly decreased in the F8KO mice after the KP treatment. Tartrate-resistant acid phosphatase (TRAP) staining of mature osteoclasts indicated that the therapeutic effect of KPs in F8KO mice was associated with the functions of KPs to inhibit RANKL-induced osteoclastogenesis by reducing serum RANKL/OPG ratio and IL-6 secretion. The present study is the first to address the potentials of KPs for the treatment of hemophilia-induced osteoporosis in mice and it also provides useful information for the application of KPs as a complementary therapy for the treatment of osteoporosis in hemophilic patients.

It is well known that canine factor VIII (cFVIII) has a higher specific activity than does human FVIII (hFVIII), and it has been previously demonstrated that cFVIII light chain is able to enhance hFVIII activity. The goal of this study was to first determine which amino acids in cFVIII light chain were responsible for enhancing hFVIII activity, and second to use these amino acids to develop a hFVIII variant with enhanced functional activity. We systemically screened segments of cFVIII light chain by testing an array of human-canine light chain hybrids and found that canine amino acids 1857–2147 were key to this enhancement. Each canine amino acid within this span was screened individually using a negative selection method, which led to the identification of 12 aa (JF12) in the FVIII light chain that could enhance activity. Substitution of the corresponding 12 aa into hFVIII (hFVIIIJF12BDD) elevated the specific activity profile in vitro. Furthermore, hFVIIIJF12BDD expressed an in vivo-displayed increased coagulation activity compared to wild-type, while maintaining normal secretion efficiency. In conclusion, we identified the amino acids in cFVIII that are the key determinants for higher specific activity and may be the basis for future development of therapeutic treatments for hemophilia A.

Hemophilia A (HA) is a F8 gene mutational disorder resulting in deficiency or dysfunctional FVIII protein. However, surprisingly, in few cases, HA is manifested even without mutations in F8. To understand this anomaly, we recently sequenced microRNAs (miRNAs) of two patients with mild and moderate HA with no F8 gene mutations and selected two highly expressing miRNAs, miR-374b-5p and miR-30c-5p, from the pool to explain the FVIII deficiency that could be mediated by miRNA-based F8/FVIII suppression. In this report, an established orthogonal in vivo RNA-affinity purification approach was utilized to directly identify a group of F8-interacting miRNAs and we tested them for F8/FVIII suppression. From this pool, two miRNAs, miR-19b-3p and miR-186-5p, were found to be upregulated in a severe HA patient with a mutation in the F8 coding sequence and two HA patients without mutations in the F8 coding sequence were selected to demonstrate their role in F8 gene expression regulation in mammalian cells. Overall, these results provide further evidence for the hypothesis that by targeting the 3′UTR of F8, miRNAs can modulate FVIII protein levels. This mechanism could either be the primary cause of HA in patients who lack F8 mutations or control the severity of the disease in patients with F8 mutations.

Hemophilia A is a worldwide disorder of coagulation system. It is a male disorder, yet females with hemophilia are rarely seen in communities with high rate of consanguineous marriages. The abnormalities in factor VIII gene transfer as an X-linked pattern in the family, affects as many as one-third of patients who had no family history of abnormality and thus the occurrence of a sporadic mutation could be documented. Hemorrhagic symptoms usually correlate with the plasma level of factor VIII and comprise a wide range of hemorrhagic pictures, including from fatal spontaneous bleeding in the brain to ecchymosis of the skin. The coagulation study needs to differentiate between the two types of hemophilia A and B as well as the categorization of the disease severity. In the developing countries, due to limitations in diagnostic hemostasis facilities and a scant number of experts in the field, it is estimated that noticeable numbers of undiagnosed patients with hemophilia A exist. Occasionally, we encounter undiagnosed cases by general physicians while having hemorrhagic symptoms. The purpose of this review is to recap clinical and diagnostic parameters, pitfalls, and interpretation of coagulation assay in hemophilia A. A literature review was done in PubMed and Scopus medical search engines using the keywords “Hemophilia” and “Haemophilia”. A time limitation for the publication beyond 1995 and publication in the English language were considered. A total of 94 original articles and chapters of books was selected for the current review. Additionally, a comprehensive and up-to-date information on the clinical and laboratory features for the diagnosis of hemophilia is also presented.

Hemophilia A is a worldwide disorder of coagulation system. It is a male disorder, yet females with hemophilia are rarely seen in communities with high rate of consanguineous marriages. The abnormalities in factor VIII gene transfer as an X-linked pattern in the family, affects as many as one-third of patients who had no family history of abnormality and thus the occurrence of a sporadic mutation could be documented. Hemorrhagic symptoms usually correlate with the plasma level of factor VIII and comprise a wide range of hemorrhagic pictures, including from fatal spontaneous bleeding in the brain to ecchymosis of the skin. The coagulation study needs to differentiate between the two types of hemophilia A and B as well as the categorization of the disease severity. In the developing countries, due to limitations in diagnostic hemostasis facilities and a scant number of experts in the field, it is estimated that noticeable numbers of undiagnosed patients with hemophilia A exist. Occasionally, we encounter undiagnosed cases by general physicians while having hemorrhagic symptoms. The purpose of this review is to recap clinical and diagnostic parameters, pitfalls, and interpretation of coagulation assay in hemophilia A. A literature review was done in PubMed and Scopus medical search engines using the keywords "Hemophilia" and "Haemophilia". A time limitation for the publication beyond 1995 and publication in the English language were considered. A total of 94 original articles and chapters of books was selected for the current review. Additionally, a comprehensive and up-to-date information on the clinical and laboratory features for the diagnosis of hemophilia is also presented. [ABSTRACT FROM AUTHOR]

Background. Hemophilia A is a chromosome X-linked bleeding disorder due to mutations in the FVIII gene. There are 163 hemophilia A patients in Slovene registry for Hemophilia. 74 have severe hemophilia A and 50% of patients with severe hemophilia A have inversion of intron 22 that is detected using the LD-PCR method. Point mutations are detected by amplification of exons of the factor VIII gene followed with a direct sequencing technique.Results. In the Slovene population we managed to determine a genetic mutation in 67/163 patients, 36/67 have inversion of intron 22 and another 31/67 have 12 different point mutations in the FVIII gene which cause hemophilia A. Three of them are so far found only among Slovene patients.Conclusions. The identification of hemophilia mutations is of great importance for the timely discovery of the hemophilia carriers and the pre-natal diagnostics of hemophilia A.