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Background: Hemophilia A (HA) is an X-linked bleeding disorder diagnosed by a deficiency in factor VIII (FVIII). For severe HA (SHA), prophylaxis clotting factor concentrates (CFC) has become the standard of care; however, it imparts a high treatment burden and typically results in an annualized bleeding rate (ABR) of 2-6. Emicizumab, a subcutaneously administered FVIII substitute, has become the de facto standard-of-care prophylaxis for children with SHA in many countries. Previous clinical trials of emicizumab have assessed ABR in patients greater than 12 years without inhibitors, and in children less than 12 years with inhibitors; however, there is little information published regarding the ABR of emicizumab compared to CFC in non-inhibitor SHA children., Methods: Using a retrospective electronic medical record chart review, we conducted a self-control analysis of 15 patients less than 12 years of age during equivalent periods of CFC versus emicizumab prophylaxis., Results: The mean ABR on CFC and emicizumab was 1.79 and 1.13 (p = .092), respectively, with a substantially decreased rate of joint bleeds (CFC 0.94; emicizumab 0.33; p = .001) and spontaneous bleeds (CFC 0.79; emicizumab 0.23; p = .008). No safety events were recorded for patients while administering emicizumab. The mean annual cost of CFC prophylaxis was $515,340 (SD $199,540), compared to $328,410 (SD $137,230) for emicizumab prophylaxis (p < .001)., Conclusion: Emicizumab resulted in an improved ABR compared to CFC, especially for joint and spontaneous bleeds, had fewer administration complications, and was substantially less expensive compared to CFC prophylaxis; however, more research is necessary for a complete understanding of the effect of emicizumab on joint health and muscle bleeds., (© 2024 The Author(s). Pediatric Blood & Cancer published by Wiley Periodicals LLC.)

Abstract: Fitusiran, a subcutaneous investigational small interfering RNA therapeutic, targets antithrombin to rebalance hemostasis in people with hemophilia A or B (PwHA/B), irrespective of inhibitor status. This phase 3, open-label study evaluated the efficacy and safety of fitusiran prophylaxis in males aged ≥12 years with hemophilia A or B, with or without inhibitors, who received prior bypassing agent (BPA)/clotting factor concentrate (CFC) prophylaxis. Participants continued their prior BPA/CFC prophylaxis for 6 months before switching to once-monthly 80 mg fitusiran prophylaxis for 7 months (onset and efficacy periods). Primary end point was annualized bleeding rate (ABR) in the BPA/CFC prophylaxis and fitusiran efficacy period. Secondary end points included spontaneous ABR (AsBR) and joint ABR (AjBR). Safety and tolerability were assessed. Of 80 enrolled participants, 65 (inhibitor, n = 19; noninhibitor, n = 46) were eligible for ABR analyses. Observed median ABRs were 6.5 (interquartile range [IQR], 2.2-19.6)/4.4 (IQR, 2.2-8.7) with BPA/CFC prophylaxis vs 0.0 (IQR, 0.0-0.0)/0.0 (IQR, 0.0-2.7) in the corresponding fitusiran efficacy period. Estimated mean ABRs were substantially reduced with fitusiran by 79.7% (P = .0021) and 46.4% (P = .0598) vs BPA/CFC prophylaxis, respectively. Forty-one participants (63.1%) experienced 0 treated bleeds with fitusiran vs 11 (16.9%) with BPAs/CFCs. Median AsBR and AjBR were both 2.2 with BPA/CFC prophylaxis and 0.0 in the fitusiran efficacy period. Two participants (3.0%) experienced suspected or confirmed thromboembolic events with fitusiran. Once-monthly fitusiran prophylaxis significantly reduced bleeding events vs BPA/CFC prophylaxis in PwHA/B, with or without inhibitors, and reported adverse events were generally consistent with previously identified risks of fitusiran. This trial was registered at www.ClinicalTrials.gov as #NCT03549871., (© 2024 American Society of Hematology. Published by Elsevier Inc. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Abstract: Subcutaneous emicizumab enables prophylaxis for people with hemophilia A (HA) from birth, potentially reducing risk of bleeding and intracranial hemorrhage (ICH). HAVEN 7 (NCT04431726) is the first clinical trial of emicizumab dedicated to infants, designed to investigate the efficacy, safety, pharmacokinetics, and pharmacodynamics of emicizumab in those aged ≤12 months with severe HA without factor VIII (FVIII) inhibitors. Participants in this phase 3b trial received emicizumab 3 mg/kg maintenance dose every 2 weeks for 52 weeks and are continuing emicizumab during the 7-year long-term follow-up. Efficacy end points included annualized bleed rate (ABR): treated, all, treated spontaneous, and treated joint bleeds. Safety end points included adverse events (AEs), thromboembolic events (TEs), thrombotic microangiopathies (TMAs), and immunogenicity (anti-emicizumab antibodies [ADAs] and FVIII inhibitors). At primary analysis, 55 male participants had received emicizumab (median treatment duration: 100.3; range, 52-118 weeks). Median age at informed consent was 4.0 months (range, 9 days to 11 months 30 days). Model-based ABR for treated bleeds was 0.4 (95% confidence interval, 0.30-0.63), with 54.5% of participants (n = 30) having zero treated bleeds. No ICH occurred. All 42 treated bleeds in 25 participants (45.5%) were traumatic. Nine participants (16.4%) had ≥1 emicizumab-related AE (all grade 1 injection-site reactions). No AE led to treatment changes. No deaths, TEs, or TMAs occurred. No participant tested positive for ADAs. Two participants were confirmed positive for FVIII inhibitors. This primary analysis of HAVEN 7 indicates that emicizumab is efficacious and well tolerated in infants with severe HA without FVIII inhibitors., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Background: The pathfinder6 (NCT02137850) international phase 3 trial examined immunogenicity, safety, and efficacy of the extended half-life factor VIII (FVIII) replacement product N8-GP (turoctocog alfa pegol; Esperoct) in previously untreated patients (PUPs) with hemophilia A., Objectives: We present end-of trial results for extended PUP N8-GP treatment for up to a median (range) 2.5 (0.0; 7.4) years., Patients/methods: Longer-term N8-GP treatment in PUPs with hemophilia A was examined. The prophylaxis regimen was ∼60 IU/kg N8-GP i.v. twice weekly, or every 3 or 7 days. The primary endpoint was the incidence of FVIII inhibitors., Results: Overall, 81 patients received N8-GP and were included in this analysis. The inhibitor incidence was 30.0% (15.7% high-titer [>5 BU]) for the extension phase. Patients had a median (range) 2.9 (0.1; 7.2) years of prophylaxis following the pre-prophylaxis period. During prophylaxis, the median annualized bleeding rate (ABR) (interquartile range) was 1.4 (0.6; 3.5), 13% of patients experienced no bleeding episodes, and 55.1% of patients experienced no spontaneous bleeds. The proportion of patients without any spontaneous bleeding episodes increased after the first year of prophylaxis. The hemostatic success rate in the treatment of bleeding episodes was 87.6%. No additional safety concerns were observed in patients with previously reported observation of temporarily decreased incremental recovery (IR)., Conclusion: Long-term end-of-trial PUP N8-GP prophylaxis data indicate that PUPs respond well to long-term N8-GP treatment. The inhibitor incidence was consistent with previous results. Median ABR during prophylaxis was 1.4. There were no lasting clinical impacts or safety concerns for patients with an observation of temporarily decreased IR., Competing Interests: Declaration of competing interests G.K. received grant and research support from Alnylam, Bayer, BPL, Opko Biologics, Pfizer, Roche, and Takeda, and participated in advisory boards and received honoraria for consultancy/lectures from Alnylam, Bayer, Biomarine, CSL, Novo Nordisk, Opko Biologics, Pfizer, Takeda, ROCHE, Sanofi, and Uniquore. A.C. participated in the advisory board of Novo Nordisk and received honoraria from Novo Nordisk, Grifols, Takeda, and Roche. Tadashi Matsushita participated in the advisory boards for Takeda, Bayer, Novo Nordisk, Chugai, and Pfizer; received educational and investigational support from Chugai and Novo Nordisk; received honoraria from Takeda, Bayer, Sanofi, Chugai, CSL, JB, KMB, Novo Nordisk, Fujimoto, Sysmex, and Guy Young; and received personal fees from Novo Nordisk during the conduct of the study. C.M. received consultancy or speaker fees from Bayer, Biotest, CSL Behring, Grifols, Novo Nordisk, Roche, and Takeda; received travel support from Bayer, Biotest, CSL Behring, and Novo Nordisk; and received institutional research support from Bayer, Baxalta/Shire/Takeda, Biotest, CSL Behring, Novo Nordisk, and Sobi. V.Y. and M.Z. are employees of Novo Nordisk., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Haemophilia treatment centres (HTCs) and healthcare providers (HCPs) will need to adapt to a new treatment paradigm with the emergence of adeno-associated virus (AAV)-based gene therapy for the treatment of haemophilia in adults., Aim: This review examines the upcoming patient and institutional journeys, along with practical aspects of preparedness for clinical delivery of gene therapy by HTCs., Methods: Based on our clinical experience and examination of published literature, we explored the parallel journeys for patients and treatment centres to navigate before, during, and after administration of gene therapy., Results: The patient journey includes: information gathering; decision making; comprehensive patient assessment; preparation for the infusion itself; short- and long-term monitoring; lifestyle modifications; and the possible need for immunosuppressive treatment. Informed decision-making may require patient education with extensive discussions and an understanding that not all people with haemophilia will choose or be eligible for gene therapy, although eligibility criteria continue to evolve. The institutional journey includes: consideration of biosafety procedures; planning for product procurement, handling, storage, and administration; development of detailed protocols and guidance documents; contingency planning for immunosuppressive and haemostatic management; consideration of clinical capabilities and staff training needs; coordination of efforts by the full multidisciplinary team; and collaboration between referring, dosing, and follow-up treatment centres. Documented protocols and guidance documents are pivotal for this complex therapy to ensure safe handling, optimal delivery, and post-infusion management and follow-up., Conclusion: Successful implementation of this new treatment modality will require communication and collaboration among multiple stakeholders., (© 2023 The Authors. Haemophilia published by John Wiley & Sons Ltd.)

Introduction: In recent years, there has been increased focus on individualizing treatment for persons with hemophilia including pharmacokinetic-guided (PK) dosing., Aims: In this retrospective study clinical outcomes before and after PK-guided prophylaxis were examined., Materials and Methods: Eight Haemophilia Treatment Centres from the United States participated in the study and included 132 patients classified into two cohorts: those undergoing a PK-assessment for product switch (switchers) or to optimize treatment (non-switchers). Subset analyses for the two most common products and patients with dosing per prescription label were included for annual bleeding rates (ABR), mean weekly consumption outcomes, and annualized cost of prophylaxis., Results: The most common products before and after index date were octocog alfa, rurioctocog alfa pegol, and efmoroctocog alfa. Seventy-four (56%) patients were identified as switchers and 58 (44%) patients were classified as non-switchers. The majority of patients (78.0%) experienced either a decrease in ABR post-index or maintained 0 ABR during pre- and post-index time periods, with similar proportions identified in both switchers (77.0%) and non-switchers (79.3%) populations. Non-switchers were identified as having no significant change in cost of therapy, while switchers experienced increased cost of therapy driven by higher price of extended half-life products. Within subset analyses, patients receiving rurioctocog alfa pegol and efmoroctocog alfa had mean ABR under 1 after index date., Conclusion: PK-guided prophylaxis has the potential to improve clinical outcomes without increase in cost of therapy for patients maintaining product and can aid in maintaining effective protection against bleeds in those switching product., (© 2023 Takeda Pharmaceuticals USA, Inc and The Authors. Haemophilia published by John Wiley & Sons Ltd.)

Competing Interests: Declaration of competing interests G.Y. has received honoraria from Apcintex, BioMarin, CSL Behring, Genentech/Roche, Hema Biologics/LFB, Novo Nordisk, Octapharma, Pfizer, Sanofi Genzyme, Spark, and Takeda and funds for research support from Genentech/Roche and Takeda. M.M. has received honoraria for lecturing and grant reviewing as well as is on advisory committee of NovoNordisk, Takeda, Grifols, and Sanofi.

Introduction: Bypassing agents (BPAs) are used to treat acute bleeding episodes, manage bleeding during perioperative care, and prophylactically minimize bleed occurrence in persons with hemophilia A or B with inhibitors (PwHABI). However, the effectiveness of BPAs that have been prescribed for the last several decades can be variable, motivating the development of a new recombinant activated factor VII, eptacog beta., Areas Covered: This review covers key eptacog beta findings from phase 1b and phase 3 (PERSEPT) clinical trials, which formed the basis for its regulatory approval to treat PwHABI ages 12 and older. Descriptions of eptacog beta structure and glycosylation profile, mechanism of action, preclinical study results, and cost analyses are also presented., Expert Opinion: PwHABI have had only two options for bleed treatment for the past several decades. With its distinct glycosylation profile, eptacog beta offers a novel therapy aiming to improve upon BPAs currently in use, providing an option with more than one dosing regimen and a rapid response that allows most bleeds to be treated with just one dose. This has become particularly important given the use of subcutaneous medications (e.g., emicizumab) for prophylaxis of bleeding. Clinicians should consider eptacog beta as a BPA for all PwHABI.

Background: Fitusiran, a subcutaneous investigational small interfering RNA therapeutic, targets antithrombin to rebalance haemostasis in people with haemophilia A or haemophilia B, irrespective of inhibitor status. We evaluated the efficacy and safety of fitusiran prophylaxis in people with haemophilia A or haemophilia B with inhibitors., Methods: This multicentre, randomised, open-label phase 3 study was done at 26 sites (primarily secondary or tertiary centres) in 12 countries. Men, boys, and young adults aged 12 years or older with severe haemophilia A or haemophilia B with inhibitors previously treated with on-demand bypassing agents were randomly assigned (2:1) to receive once-a-month 80 mg subcutaneous fitusiran prophylaxis (fitusiran prophylaxis group) or to continue with bypassing agents on-demand (bypassing agents on-demand group) for 9 months. The primary endpoint was mean annualised bleeding rate during the efficacy period in the intention-to-treat population estimated by negative binomial model. Safety was assessed as a secondary endpoint in the safety population. This trial is complete and is registered with ClinicalTrials.gov, NCT03417102., Findings: Between Feb 14, 2018, and June 23, 2021, 85 participants were screened for inclusion, of whom 57 (67%; 57 [100%] men; median age 27·0 years [IQR 19·5-33·5]) were randomly assigned: 19 (33%) participants to the bypassing agent on-demand group and 38 (67%) participants to the fitusiran prophylaxis. Negative binomial model-based mean annualised bleeding rate was significantly lower in the fitusiran prophylaxis group (1·7 [95% CI 1·0-2·7]) than in the bypassing agents on-demand group (18·1 [10·6-30·8]), corresponding to a 90·8% (95% CI 80·8-95·6) reduction in annualised bleeding rate in favour of fitusiran prophylaxis (p<0·0001). 25 (66%) participants had zero treated bleeds in the fitusiran prophylaxis group versus one (5%) in the bypassing agents on-demand group. The most frequent treatment-emergent adverse event in the fitusiran prophylaxis group was increased alanine aminotransferase in 13 (32%) of 41 participants in the safety population; there were no increased alanine aminotransferase treatment-emergent adverse events in the bypassing agents on-demand group. Suspected or confirmed thromboembolic events were reported in two (5%) participants in the fitusiran prophylaxis group. No deaths were reported., Interpretation: Subcutaneous fitusiran prophylaxis resulted in statistically significant reductions in annualised bleeding rate in participants with haemophilia A or haemophilia B with inhibitors, with two-thirds of participants having zero bleeds. Fitusiran prophylaxis might show haemostatic efficacy in participants with haemophilia A or haemophilia B with inhibitors; therefore, the therapeutic might have the potential to improve the management of people with haemophilia., Funding: Sanofi., Competing Interests: Declaration of interests GY reports grants from Genentech/Roche, Grifols, and Takeda; and speaking and consultancy fees from Apcintex, BioMarin, Genentech/Roche, Grifols, Hema Biologics/ Laboratoire français du Fractionnement et des Biotechnologies biomedicaments, Novo Nordisk, Pfizer, Rani, Sanofi, Spark, Takeda, and UniQure. AS reports membership on advisory committees or grant review committees for Sanofi, Takeda, Novo Nordisk, Roche, Pfizer, and Bayer Healthcare and reports research funding from Roche, Novo Nordisk, Sanofi, and Pfizer. KK reports grants and consultancy fees from Novo Nordisk, Roche, and Takeda. JSa is the president of the Malaysian Society of Patient Blood Management. HT reports grants or honorarium from Sanofi, Takeda, Roche, and CSL Behring. SP, ZQ, and SK are employees and equity holders in Sanofi. BM was an employee and equity holder in Sanofi at the time of the study and has divested equity in Sanofi in the past 24 months; he is an employee of Editas Medicine. SA is an employee and equity holder in Sanofi, and a member of the WEST advisory committee. SR reports consultancy fees from Reliance Life Sciences; grants for conference attendance from Takeda; and fees for attendance at advisory board meetings from Pfizer, Sanofi, Sigilon, and Takeda. All other authors declare no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Background: The National Hemophilia Foundation (NHF) conducted extensive, inclusive community consultations to guide prioritization of research in coming decades in alignment with its mission to find cures and address and prevent complications enabling people and families with blood disorders to thrive., Research Design and Methods: With the American Thrombosis and Hemostasis Network, NHF recruited multidisciplinary expert working groups (WG) to distill the community-identified priorities into concrete research questions and score their feasibility, impact, and risk. WG6 was charged with identifying the infrastructure, workforce development, and funding and resources to facilitate the prioritized research. Community input on conclusions was gathered at the NHF State of the Science Research Summit., Results: WG6 detailed a minimal research capacity infrastructure threshold, and opportunities to enable its attainment, for bleeding disorders centers to participate in prospective, multicenter national registries. They identified challenges and opportunities to recruit, retain, and train the diverse multidisciplinary care and research workforce required into the future. Innovative collaborative approaches to trial design, resource networking, and funding to surmount obstacles facing research in rare disorders were elucidated., Conclusions: The innovations in infrastructure, workforce development, and resources and funding proposed herein may contribute to facilitating a National Research Blueprint for Inherited Bleeding Disorders.

N8-GP (turoctocog alfa pegol) is a recombinant, glycoPEGylated, extended half-life, factor VIII replacement product. Here, we examined the immunogenicity, safety, and efficacy of N8-GP in previously untreated patients (PUPs). pathfinder6 is an ongoing, open-label, phase 3 trial that enrolled PUPs with severe hemophilia A and were aged <6 years. The primary end point was the incidence of factor VIII inhibitors (≥0.6 Bethesda units [BU]). Eighty patients received ≥1 N8-GP dose and were included in this analysis; ≥50 patients had ≥50 exposure days to N8-GP. The inhibitor incidence was 29.9% (14.9% high-titer [>5 BU]). Sixty-five patients received N8-GP prophylaxis for an average of 2.17 years with a median annualized bleeding rate (interquartile range) of 1.42 (0.76; 3.13) and a 90.5% hemostatic success rate. Temporarily decreased incremental recovery (IR), defined as ≥2 consecutive measurements of IR <0.6 (IU/dL)/(IU/kg) but no inhibitors, was observed in 17 patients within 5 exposure days to N8-GP and had a strong temporal correlation with anti-polyethylene glycol immunoglobulin G antibody titers. IR returned within the expected range with continued N8-GP dosing. During the period of decreased IR, hemostatic response was similar to that of the overall trial population, and no hypersensitivity related to N8-GP or unexpected new adverse events were reported. N8-GP prophylaxis was efficacious for the prevention and treatment of bleeding episodes in PUPs with severe hemophilia A. The inhibitor incidence was 29.9%. All patients with temporarily decreased IR continuing on N8-GP dosing returned within the expected range and had no evident lack of efficacy. This trial was registered at www.clinicaltrials.gov as #NCT02137850., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Introduction: Emicizumab is a humanized bispecific monoclonal antibody licensed for patients with severe haemophilia A. Breakthrough bleeding still occurs in patients on emicizumab and can be managed with recombinant factor VIIa (rFVIIa) or activated prothrombin complex concentrate (aPCC). Thrombotic events were reported when patients on emicizumab received concomitant aPCC at relatively high doses. We studied the effect of infusing various doses of aPCC to patients on emicizumab., Material and Methods: Nine patients with severe haemophilia A with inhibitors who are on emicizumab were recruited to participate. Patients were infused with varying doses of aPCC in vivo. Samples were tested with thrombin generation (TG) assay., Results: In the current in vivo arm of the study four out of nine patients reached the highest dose, 75 U/kg of aPCC and six out of nine patients were actually eligible for the highest dose. In the previous in vitro arm of the study seven out of eight patients reached the normal plasma with spiking aPCC at a very low concentration equivalent to 5 U/kg., Conclusion: The in vitro portion of the study demonstrated that clinically relevant concentrations of aPCC resulted in excessive TG, however, in vivo administration of aPCC to the same patients demonstrated that most of the patients had normal TG at the approved doses of aPCC. In the management of breakthrough bleeding clinicians should heed the boxed warning for concomitant use of emicizumab and aPCC, however, should also be aware that low doses of aPCC may not result in sufficient TG., (© 2022 John Wiley & Sons Ltd.)

Many people with hemophilia A (PwHA) undergo surgery in their lifetime, often because of complications of their disease. Emicizumab is the first bispecific monoclonal antibody prophylactic therapy for PwHA, and its efficacy and safety have been previously demonstrated; however, there is a need to build an evidence base on the management of PwHA on emicizumab undergoing surgery. Data from the HAVEN 1-4 phase 3 clinical trials were pooled to provide a summary of all minor and major surgeries in PwHA with or without factor VIII (FVIII) inhibitors who were receiving emicizumab prophylaxis. Overall, 233 surgeries were carried out during the HAVEN 1-4 trials: 215 minor surgeries (including minor dental and joint procedures, central venous access device placement or removal, and endoscopies) in 115 PwHA (64 with FVIII inhibitors) and 18 major surgeries (including arthroplasty and synovectomy) in 18 PwHA (10 with FVIII inhibitors). Perioperative hemostatic support was at the discretion of the treating physician. Overall, the median (interquartile range [IQR]) age was 33.5 (13.0-49.0) years and the median (IQR) emicizumab exposure time before surgery was 278.0 (177.0-431.0) days. Among the 215 minor surgeries, 141 (65.6%) were managed without additional prophylactic factor concentrate, and of those, 121 (85.8%) were not associated with a postoperative bleed. The majority (15 of 18 [83.3%]) of major surgeries were managed with additional prophylactic factor concentrate. Twelve (80.0%) of these 15 surgeries were associated with no intraoperative or postoperative bleeds. The data demonstrate that minor and major surgeries can be performed safely in PwHA receiving emicizumab prophylaxis. These trials are registered at www.clinicaltrials.gov as #NCT02622321, #NCT02795767, #NCT02847637, and #NCT03020160., (© 2022 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Introduction: Eptacog beta is a new recombinant activated human factor VII bypassing agent approved in the United States for the treatment and control of bleeding in patients with haemophilia A or B with inhibitors 12 years of age or older., Aim: To prospectively assess in a phase 3 clinical trial (PERSEPT 2) eptacog beta efficacy and safety for treatment of bleeding in children <12 years of age with haemophilia A or B with inhibitors., Methods: Using a randomised crossover design, subjects received initial doses of 75 or 225 μg/kg eptacog beta followed by 75 μg/kg dosing at predefined intervals (as determined by clinical response) to treat bleeding episodes (BEs). Treatment success criteria included a haemostasis evaluation of 'excellent' or 'good' without use of additional eptacog beta, alternative haemostatic agent or blood product, and no increase in pain following the first 'excellent' or 'good' assessment., Results: Treatment success proportions in 25 subjects (1-11 years) who experienced 546 mild or moderate BEs were 65% in the 75 μg/kg initial dose regimen (IDR) and 60% in the 225 μg/kg IDR 12 h following initial eptacog beta infusion. By 24 h, the treatment success proportions were 97% for the 75 μg/kg IDR and 98% for the 225 μg/kg IDR. No thrombotic events, allergic reactions, neutralising antibodies or treatment-related adverse events were reported., Conclusion: Both 75 and 225 μg/kg eptacog beta IDRs provided safe and effective treatment and control of bleeding in children <12 years of age., (© 2022 The Authors. Haemophilia published by John Wiley & Sons Ltd.)

Despite current therapies, there remains an unmet need for treatment for patients with hemophilia. The main parts of two phase 2 trials established clinical proof-of-concept for once-daily, subcutaneous concizumab prophylaxis in patients with hemophilia A/B with inhibitors (HAwI/HBwI; explorer4) and severe hemophilia A without inhibitors (HA; explorer5). Here, we present results from extension parts of these trials, included to evaluate longer term safety and efficacy. Both trials included main (≥24 weeks) and extension (52-102 weeks) parts, with patients receiving concizumab 0.15 mg/kg with potential dose escalation to concizumab 0.20 or 0.25 mg/kg if they experienced ≥3 treated spontaneous bleeding episodes within 12 weeks. Endpoints included annualized bleeding rate (ABR), adverse events (AEs), and occurrence of antidrug antibodies. Thromboembolic events were AEs of special interest. Thirty-six patients with HA, 15 with HAwI, and 10 with HBwI were exposed to concizumab. Estimated ABRs during the main + extension parts at last dose level were 4.8 (95% confidence interval [CI], 3.2-7.2) and 6.4 (95% CI, 4.1-9.9) in explorer4 and explorer5, respectively (spontaneous ABRs were 1.8 [95% CI, 1.2-2.6] and 2.1 [95% CI, 1.3-3.3]). Most AEs were mild, with no deaths, events leading to withdrawal, or thromboembolic events. Anti-drug antibodies developed in 25% of patients and were low titer and transient, with no observed clinical effect in most cases. Results of the main + extension parts of these trials were consistent with results of the main parts. Ongoing phase 3 trials will further evaluate concizumab as a once-daily, subcutaneous treatment across hemophilia subtypes. These trials were registered at www.clinicaltrials.gov as #NCT03196284 and #NCT03196297., (© 2022 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Background:  Predicting annualized bleeding rate (ABR) during factor VIII (FVIII) prophylaxis for severe hemophilia A (SHA) is important for long-term outcomes. This study used supervised machine learning-based predictive modeling to identify predictors of long-term ABR during prophylaxis with an extended half-life FVIII., Methods:  Data were from 166 SHA patients who received N8-GP prophylaxis (50 IU/kg every 4 days) in the pathfinder 2 study. Predictive models were developed to identify variables associated with an ABR of ≤1 versus >1 during the trial's main phase (median follow-up of 469 days). Model performance was assessed using area under the receiver operator characteristic curve (AUROC). Pre-N8-GP prophylaxis models learned from data collected at baseline; post-N8-GP prophylaxis models learned from data collected up to 12-weeks postswitch to N8-GP, and predicted ABR at the end of the outcome period (final year of treatment in the main phase)., Results:  The predictive model using baseline variables had moderate performance (AUROC = 0.64) for predicting observed ABR. The most performant model used data collected at 12-weeks postswitch (AUROC = 0.79) with cumulative bleed count up to 12 weeks as the most informative variable, followed by baseline von Willebrand factor and mean FVIII at 30 minutes postdose. Univariate cumulative bleed count at 12 weeks performed equally well to the 12-weeks postswitch model (AUROC = 0.75). Pharmacokinetic measures were indicative, but not essential, to predict ABR., Conclusion:  Cumulative bleed count up to 12-weeks postswitch was as informative as the 12-week post-switch predictive model for predicting long-term ABR, supporting alterations in prophylaxis based on treatment response., Competing Interests: P.C. has received grant/research support from Alnylam, Bayer, Biogen, Cangene, CSL Behring, Freeline Therapeutics, Novo Nordisk, Pfizer, Sobi, and Takeda (Shire); and consultancy fees from Bayer, Biogen, Cangene, CSL Behring, Chugai, Freeline Therapeutics, Novo Nordisk, Pfizer, Roche, Spark Therapeutics, Sobi, and Takeda (Shire). K.H. has received consultancy fees from Novo Nordisk. V.J-.Y. has received reimbursement for attending symposia/congresses and/or honoraria for speaking and/or honoraria for consulting, and/or funds for research from Bayer, CSL Behring, Grifols, Novo Nordisk, Octapharma, Sobi, and Takeda. G.Y. has received consultancy fees from Novo Nordisk. S.B.F. is a shareholder and employee of Novo Nordisk. A.C. is an employee of IQVIA UK, which received funding from Novo Nordisk to design, conduct, and interpret the reported analyses. E.S. is an employee of IQVIA AG, which received funding from Novo Nordisk to design, conduct, and interpret the reported analyses. A.T. has received grants for research/study support from Bayer, Biotest, Chugai, Novo Nordisk, Octapharma, Pfizer, Roche, SOBI, and Takeda; and received honoraria for lectures/consultancy from Bayer, Biotest, Chugai, CSL Behring, Novo Nordisk, Octapharma, Pfizer, Roche, SOBI, and Takeda., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/).)

Introduction: Challenges with personalised prophylaxis in haemophilia remain, including designing unique dosing schedules that require continual adjustments and monitoring using complex sampling procedures., Aim: To assess long-term efficacy and pharmacokinetic outcomes with fixed-dose N8-GP prophylaxis., Methods: Descriptive analyses were performed on data from the pathfinder 2 and pathfinder 5 trials of patients with severe haemophilia A. Bleed frequency and reoccurrence were assessed in relation to several clinical criteria of interest. Bleed risk relative to time since last dose was assessed using calculated annualised bleeding rate (ABR). Long-term ABR and mean factor VIII (FVIII) trough levels were assessed in patients who received consistent N8-GP prophylaxis every 4 days (Q4D)., Results: During pathfinder 2, 117/136 patients with study-drug exposure of ≥600 days experienced bleeding episodes; 8.6% of bleeds were reoccurring bleeds; bleed reoccurrence decreased over time. For patients who received consistent Q4D prophylaxis across the trial (n = 61), mean ABR decreased from 3.5 bleeds/year (Year 1) to 1.6 bleeds/year (Year 6); mean FVIII trough levels stabilised at approximately 5% (Year 6). Across patients who received prophylaxis at some point during pathfinder 2 (n = 177), 125/126 (99%) reoccurring bleeds were joint bleeds. For patients receiving Q4D prophylaxis, bleeding risk generally increased as the time since the last prophylaxis dose increased. A similar reduction in ABR and stabilisation of trough level was observed in pathfinder 5., Conclusion: Long-term exposure (> 5 years) to fixed-dose N8-GP prophylaxis resulted in a protective haemostatic effect, with reduction in bleed frequency and reoccurrence, and stabilisation of FVIII trough level over time., (© 2021 The Authors. Haemophilia published by John Wiley & Sons Ltd.)

Introduction: Hemophilia is a lifelong, genetic-bleeding disorder, which inadequately treated results in permanent joint damage. It is characterized by spontaneous and trauma-related bleeding episodes. In the last 50 years, treatment has seen dramatic improvements which have improved the quality of life of persons with hemophilia., Areas Covered: This review will provide a summary of current pharmacological approaches for hemophilia A as well as discuss novel agents which are either approved recently or in phase II-III clinical trials, plasma-derived and recombinant factor VIII (FVIII) products, extended half-life FVIII products, bypassing agents and non-replacement therapies., Expert Opinion: Novel therapies are already changing the way that hemophilia A is managed, and as more new therapies get approved, there will be a revolution in the management of this serious condition. Clinicians will have both the opportunities as well as the challenges of incorporating such new technologies into clinical practice.

Introduction: Haemophilia patients with inhibitors often require a bypassing agent (BPA) for bleeding episode management. Eptacog beta (EB) is a new FDA-approved recombinant activated human factor VII BPA for the treatment and control of bleeding in haemophilia A or B patients with inhibitors (≥12 years of age). We describe here the EB safety profile from the three prospective Phase 3 clinical trials performed to date., Aim: To assess EB safety, immunogenicity and thrombotic potential in children and adults who received EB for treatment of bleeding and perioperative care., Methods: Using a randomized crossover design, 27 subjects in PERSEPT 1 (12-54 years) and 25 subjects in PERSEPT 2 (1-11 years) treated bleeding episodes with 75 or 225 μg/kg EB initially followed by 75 μg/kg dosing at predefined intervals as determined by clinical response. Twelve PERSEPT 3 subjects (2-56 years) received an initial preoperative infusion of 75 μg/kg (minor procedures) or 200 μg/kg EB (major surgeries) with subsequent 75 μg/kg doses administered intraoperatively and post-operatively as indicated. Descriptive statistics were used for data analyses., Results: Sixty subjects who received 3388 EB doses in three trials were evaluated. EB was well tolerated, with no allergic, hypersensitivity, anaphylactic or thrombotic events reported and no neutralizing anti-EB antibodies detected. A death occurred during PERSEPT 3 and was determined to be unlikely related to EB treatment by the data monitoring committee., Conclusion: Results from all three Phase 3 trials establish an excellent safety profile of EB in haemophilia A or B patients with inhibitors for treatment of bleeding and perioperative use., (© 2021 The Authors. Haemophilia published by John Wiley & Sons Ltd.)

Introduction: Emicizumab has been shown to be safe and effective for prevention of bleeds in patients with severe haemophilia A (SHA), both with and without inhibitors. The subcutaneous administration and long half-life make emicizumab an attractive option for prophylaxis in infants with SHA, however data to inform treatment decisions in this younger age group are almost absent., Aim: The aim of this report is to share real world experience to illustrate how the availability of emicizumab has shifted the prophylaxis paradigm in the management of infants with SHA., Method: We selected four cases from our own cohort of infants with SHA to outline the rationale for emicizumab prophylaxis in a range of scenarios familiar to paediatric haemophilia treaters., Results: In Case 1 emicizumab was commenced at 7 days following initial treatment of neonatal ICH with a FVIII infusion. In Case 2 emicizumab was commenced at 5 weeks due to parental anxiety regarding the potential for ICH during infancy. Case 3 commenced emicizumab at 15 months in lieu of standard primary prophylaxis. Case 4 switched to emicizumab prophylaxis at 14 months after a period of primary prophylaxis with FVIII concentrates to alleviate parental anxiety regarding future inhibitor development. No patient had any bleeding events after commencement of emicizumab (median follow up 12 months), and no drug-related adverse effects were observed., Conclusion: Despite the paucity of data in infants with SHA the potential role of emicizumab prophylaxis should be discussed with families when clinically relevant, with decisions tailored to individual need., (© 2021 John Wiley & Sons Ltd.)

Introduction: Emicizumab is a recombinant, humanized bispecific monoclonal antibody that mimics the function of factor VIII (FVIII) which results in a significant reduction in the annualized bleeding rate in patients with haemophilia A (HA), however, the degree with which emicizumab corrects the coagulation defect remains unclear. The objective of this study was to predict the approximate FVIII level in severe haemophilia A patients with inhibitors on emicizumab using global haemostasis assays., Materials and Methods: Patients with moderate and mild HA in the non-bleeding state and healthy controls had FVIII levels and thrombin generation assessed. Linear regression was utilized to model the FVIII levels as a function of the thrombin generation assay parameters and to make a calibration curve of FVIII levels versus peak thrombin and endogenous thrombin potential. Patients with severe haemophilia A with inhibitors on emicizumab had thrombin generation performed in the same manner and their peak thrombin and endogenous thrombin potential results were placed on the calibration curve to calculate their FVIII Equivalency of Emicizumab by Thrombin Generation (F8EmT)., Results: All patients with severe HA with inhibitors on emicizumab had F8EmT >10%, suggesting they had been converted to a mild haemophilia phenotype. The patient's weight was inversely correlated to their F8EmT., Conclusion: The results from this study suggest that the F8EmT in patients with severe HA on emicizumab falls within the range of mild haemophilia which is consistent with the data noted in the emicizumab clinical trials and in vivo studies in animals., (© 2021 John Wiley & Sons Ltd.)

Prophylaxis with emicizumab, a subcutaneously administered bispecific humanized monoclonal antibody, promotes effective hemostasis in persons with hemophilia A (PwHAs). The primary efficacy, safety, and pharmacokinetics of emicizumab were reported previously, but long-term data were limited. Here, data from 401 pediatric and adult PwHAs with/without factor VIII (FVIII) inhibitors who were enrolled in the phase 3 HAVEN 1, HAVEN 2, HAVEN 3, and HAVEN 4 studies (NCT02622321, NCT02795767, NCT02847637, NCT03020160) have been pooled to establish a long-term efficacy, safety, and pharmacokinetics profile. Across a median efficacy period of 120.4 weeks (interquartile range, 89.0-164.4) (data cutoff 15 May 2020), the model-based treated annualized bleed rate (ABR) was 1.4 (95% confidence interval [CI], 1.1-1.7). ABRs declined and then stabilized at <1 in an analysis of 24-week treatment intervals; at weeks 121 to 144 (n = 170), the mean treated ABR was 0.7 (95% CI, 0-5.0). During weeks 121 to 144, 82.4% of participants had 0 treated bleeds, 97.6% had ≤3 treated bleeds, and 94.1% reported no treated target joint bleeds. Bleeding into target joints decreased substantially. Emicizumab was well tolerated, and no participant discontinued because of adverse events beyond the 5 previously described. This data cutoff includes the previously reported 3 thrombotic microangiopathies (one in the PwHA with fatal rectal hemorrhage) and 2 thromboembolic events, all associated with activated prothrombin complex concentrate use, as well as a myocardial infarction and a venous device occlusion. With 970.3 patient-years of exposure, emicizumab prophylaxis maintained low bleed rates in PwHAs of all ages with/without FVIII inhibitors and remains well tolerated, with no new safety concerns identified., (© 2021 by The American Society of Hematology.)

Introduction: Emicizumab is a bispecific-humanized monoclonal antibody that improves hemostasis by bridging activated factor IX and factor X to substitute for the function of missing activated FVIII. It is an alternative to prophylaxis with factor VIII replacement and is associated with improved outcomes in individuals with hemophilia A with and without inhibitors., Areas Covered: Emicizumab is efficacious in reducing bleeding events when compared to on-demand treatment and factor-based prophylaxis. Except for the few thrombotic microangiopathy and thrombotic event cases mainly seen in the HAVEN 1 trial, emicizumab has an overall excellent safety profile with minimal side effects., Expert Opinion: Knowledge gaps include the efficacy and safety of emicizumab in younger age groups and those with mild or moderate hemophilia A. Future directions for research include exploring the risk of inhibitor recurrence in patients with a history of high titer inhibitor who have been successfully tolerized, who switch from factor prophylaxis to emicizumab, as well as conducting 'real world studies' to evaluate the patient's perception of emicizumab in regard to ease and tolerability in order to optimize individualized treatment plans.

Introduction: Management strategies and hemostatic treatments to achieve control of bleeding are relevant across many disease areas. Identification of primary outcomes for studies assessing hemostatic intervention was the objective of a National Heart, Lung and Blood Institute (NHLBI) sponsored multidisciplinary initiative. The aim of this report is to summarize the evidence reviewed, and the outcomes identified by the subgroup tasked to assess outcomes for inherited bleeding disorders., Methods: The subgroup decided to focus on haemophilia, the prototypal congenital bleeding disorder and the one with the largest available body of evidence. MEDLINE, EMBASE and PsycINFO, The Cochrane Review, CINAHL, and Web of Science were searched for systematic and narrative reviews on outcomes used in haemophilia clinical trials. Three different clinical goals were identified as typical objectives of future research., Results: Out of 1322 unique citations, 24 reviews published in the period 2002-2019 were included. We identified 113 outcome measures, categorized in 6 domains: health-related quality of life (HRQoL), comorbidities and mortality, overall physical functioning and participation, bleeding and hemostasis, joint health, and costs and resource use. Three different clinical goals were identified as typical objectives of future research: Episodic 'on demand' replacement therapy, prevention of bleeding (Prophylaxis), and long-term and overall impact of bleeding. For each of these scenarios, specific outcomes were recommended., Conclusions: Primary outcomes for clinical trials assessing the efficacy of hemostatic treatment in achieving control, prevention and limiting long-term consequences of bleeding in inherited bleeding disorders are suggested, and their strength and limitations discussed., (© 2021 John Wiley & Sons Ltd.)

Emicizumab, a bispecific monoclonal antibody, bridges activated factor IX (FIXa) and FX, replacing the function of missing FVIIIa to restore effective hemostasis in persons with hemophilia A (PwHA). Here we assess pharmacokinetic (PK) and pharmacodynamic (PD) biomarkers in PwHA with FVIII inhibitors in the Phase III HAVEN 1 study (NCT02622321). Blood samples from 112 PwHA receiving 1.5 mg/kg once-weekly subcutaneous emicizumab were analyzed at central laboratories. Emicizumab concentrations for PK analysis were measured via validated immunoassay. PD effects were assessed using FVIII chromogenic activity assay containing human factors (Hyphen Biophen FVIII:C), and by FXIa-triggered thrombin generation (TG). Activated partial thromboplastin time (aPTT), prothrombin time (PT), antigen levels of FIX and FX, fibrinogen, D-dimer, and prothrombin fragment 1.2 (PF1.2) levels were determined. Emicizumab trough concentrations ≥ 50 µg/mL were maintained throughout the study. FVIII-like activity and TG (peak height) correlated with emicizumab concentrations and remained above 20 U/dL and 100 nM, respectively, with a weekly maintenance dose, theoretically converting persons with severe hemophilia A to a mild disease phenotype. aPTT was normalized at subtherapeutic concentrations of emicizumab. Plasma concentrations of target antigens FIX and FX were not significantly affected by emicizumab treatment; nor were fibrinogen, PT (international normalized ratio), D-dimer, or PF1.2. The PK profile of once-weekly emicizumab in HAVEN 1 provides sustained therapeutic plasma levels, consistent with population PK models. Both the PK profile and the PD and safety biomarkers are consistent with the established efficacy of emicizumab prophylaxis in PwHA with FVIII inhibitors., Competing Interests: C.S., J.I.A., C.P., and G.G.L. are employees of F. Hoffmann-La Roche Ltd/Genentech, Inc. and hold stocks in F. Hoffmann-La Roche Ltd. J.X. is an employee of Gilead Sciences, and previous employee of F. Hoffmann-La Roche Ltd/Genentech, Inc. with stocks in F. Hoffmann-La Roche Ltd. O.C. is an employee of F. Hoffmann-La Roche Ltd. G.Y. has received grants and personal fees from Genentech, Inc./F. Hoffmann-La Roche Ltd, Takeda, and Grifols and personal fees from Novo Nordisk, UniQure, Sanofi, Spark Therapeutics, and BioMarin. C.N. has received personal fees from Bayer, CSL Behring, Freeline, LFB, Novo Nordisk, Octapharma, Pfizer, Sanofi, Shire, and Spark Therapeutics; and personal fees and other from Sobi and F. Hoffmann-La Roche Ltd. M.U.C. has received personal fees from F. Hoffmann-La Roche Ltd, Genentech, Inc., Bayer, Shire/Takeda, Pfizer, Novo Nordisk, Bioverative/Sanofi, Global Blood Therapeutics, Spark Therapeutics, BioMarin, Kedrion, Octapharma, Grifols; and has equity in Alnylam., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial-License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).)

Introduction : Immune tolerance induction (ITI) is the primary therapeutic strategy and only proven method to eradicate inhibitors to coagulation factor VIII (FVIII) in hemophilia A. Emicizumab, a humanized bispecific monoclonal antibody that mimics the function of activated FVIII, has expanded options to treat hemophilia A. The availability of emicizumab necessitates a revisit of recommendations for managing patients with inhibitors. Areas covered : Current evidence is reviewed about the concomitant use of emicizumab and FVIII concentrates during and after ITI. Areas where data are lacking are highlighted and ongoing studies designed to address these issues are described. Expert opinion : Inhibitor eradication remains a desirable goal. All patients with inhibitors should be offered at least one attempt at ITI. Emicizumab monotherapy is an option for inhibitor patients who are not candidates for ITI. Evidence is emerging about the use of emicizumab during ITI to prevent bleeds. Studies are currently addressing the safety, efficacy, and feasibility of concomitant emicizumab and FVIII in ITI. As evidence regarding the risk of inhibitor recurrence and need for continued FVIII to maintain immune tolerance post-ITI is limited, the role of emicizumab alone or in combination with FVIII after ITI is the subject of an upcoming study.

Introduction: Emicizumab is a humanized bispecific monoclonal antibody licensed for patients with severe haemophilia A with and without inhibitors. Management of breakthrough bleeding in patients with inhibitors on emicizumab involves episodic treatment with bypassing agents (BPA), activated prothrombin complex concentrate (aPCC) or recombinant activated factor VII (rFVIIa). Thrombotic events and thrombotic microangiopathy were reported when patients on emicizumab received concomitant aPCC at relatively high doses yet such events were not reported with rFVIIa. We studied the effect of spiking various concentrations of BPA on plasma taken from patients on emicizumab., Material and Methods: Eleven patients with severe haemophilia A with inhibitors who are on emicizumab were recruited to participate. Blood samples drawn from patients were spiked in vitro with varying concentrations of aPCC and rFVIIa. All samples were tested utilizing global haemostasis assays, thromboelastography and thrombin generation assay., Results: Thrombin generation increased with higher concentrations of spiked BPA with a normalized endogenous thrombin potential at a concentration of 0.05 IU/ml and 4 mcg/ml for aPCC and rFVIIa, respectively. Concentrations of aPCC in the range of licensed dosing led to excessive thrombin generation. Thromboelastography was not sufficiently sensitive., Conclusion: Due to the known thrombotic complications when emicizumab is used in conjunction with aPCC, there has been a large-scale abandonment of the use of aPCC in patients on emicizumab. However, it is possible that aPCC can be used safely with emicizumab albeit with lower doses than are typically prescribed. It would be important to test this hypothesis in a clinical study., (© 2020 John Wiley & Sons Ltd.)

Introduction: Persons with haemophilia A (PwHA) with factor (F)VIII inhibitors, including children, have impaired health-related quality of life (HRQoL). The HAVEN 2 study (NCT027955767) of paediatric PwHA with FVIII inhibitors demonstrated that subcutaneous emicizumab prophylaxis resulted in low annualizedbleed rates., Aim: We assessed the impact of emicizumab prophylaxis on the HRQoL of children and their caregivers participating in HAVEN 2., Methods: Children aged 8-11 years self-reported HRQoL using the Haemophilia-Specific Quality of Life Assessment Instrument for Children and Adolescents Short Form (Haemo-QoL SF II). Caregivers of children aged 0-11 years completed the Adapted Inhibitor-Specific Quality of Life Assessment with Aspects of Caregiver Burden. All scores were transformed to a 0-100 scale, where lower scores reflect a better HRQoL. The number of missed days from school/day care and hospitalizations was also recorded., Results: In HAVEN 2 (n = 88), the median age was 6.5 years (range: 1-15 years); 85 participants were aged < 12 years and included in this analysis, and 34 participants were aged 8-11 years, thereby eligible to complete the Haemo-QoL SF II questionnaire. The mean (standard deviation, n) baseline Haemo-QoL SF II 'Total' score was 30.2 (14.9, 30), indicating moderate impairment; with emicizumab, mean score decreased by -9.62 (7.73, 17) points to 23.0 (13.93, 20) by Week 49. The most improved domains were 'Sports & School' and 'Physical Health'. Caregivers reported similar improvements., Conclusion: Prophylactic emicizumab is accompanied by substantial and sustained improvements in HRQoL of paediatric PwHA with FVIII inhibitors and their caregivers., (© 2020 The Authors. Haemophilia published by John Wiley & Sons Ltd.)

Hemophilia A (HA) is a serious inherited bleeding disorder resulting from a deficiency of coagulation factor VIII (FVIII). Replacement therapy with intravenous infusion of FVIII can be associated with treatment failure in approximately one-third of patients secondary to the development of neutralizing alloantibodies (inhibitor). Emicizumab is a recombinant, humanized, bispecific monoclonal antibody that binds factor IXa and factor X and mimics FVIII. It has been licensed in many countries for the treatment of patients with HA with and without inhibitors with a favorable efficacy and safety profile. A 7-year-old child with severe HA and FVIII inhibitors, refractory to immune tolerance therapy, developed hematuria with nephrotic-range proteinuria after the first dose of emicizumab and subsequently also after a second dose 6 weeks later, which was associated with mild and transient leukopenia. Renal biopsy revealed a pattern of a full-house lupus nephritis. The patient fully and spontaneously recovered between 2 weeks after symptoms onset. In this report, we provide insights on a new and so far unreported renal complication associated to emicizumab treatment. Although emicizumab offers significant benefits for patient with HA, clinicians should be aware of this rare and potential serious renal adverse effect., Competing Interests: POTENTIAL CONFLICT OF INTEREST: Dr Alberio has received research support and support for the institutional hemophilia nurse program from Roche unrelated to the current study; Dr Young has received funding from Genentech/Roche unrelated to the current study; the other authors have indicated they have no potential conflicts of interest to disclose., (Copyright © 2020 by the American Academy of Pediatrics.)

Introduction: The efficacy and safety of recombinant factor VIII Fc fusion protein (rFVIIIFc) as an extended half-life treatment for severe haemophilia A were demonstrated in the Phase 3 A-LONG and Kids A-LONG studies. Eligible subjects who completed A-LONG and Kids A-LONG could enrol in ASPIRE (NCT01454739), an open-label extension study., Aim: To report the long-term safety and efficacy of rFVIIIFc in subjects with severe haemophilia A who enrolled in ASPIRE., Methods: Previously treated subjects received one or more of the following regimens: individualized prophylaxis (IP), weekly prophylaxis, modified prophylaxis or episodic treatment. Subjects could switch treatment regimen at any time. The primary endpoint was inhibitor development., Results: A total of 150 subjects from A-LONG and 61 subjects from Kids A-LONG enrolled in ASPIRE. Most subjects received the IP regimen (A-LONG: n = 110; Kids A-LONG: n = 59). Median (range) treatment duration in ASPIRE for subjects from A-LONG and Kids A-LONG was 3.9 (0.1-5.3) years and 3.2 (0.3-3.9) years, respectively. No inhibitors were observed (0 per 1000 subject-years; 95% confidence interval, 0-5.2) and the overall rFVIIIFc safety profile was consistent with prior studies. For subjects on the IP regimen, annualized bleed rates (ABR) remained low (median overall ABR for adults and adolescents was <1.0) and extended-dosing intervals were maintained (median of 3.5 days) for the majority of subjects in ASPIRE., Conclusion: ASPIRE results, which include up to 5 years of follow-up data, confirm earlier reports on the consistent and well-characterized safety and efficacy of rFVIIIFc treatment for severe haemophilia A., (© 2020 The Authors. Haemophilia published by John Wiley & Sons Ltd.)

Introduction : Novel non-replacement therapies (e.g. emicizumab) have improved the management of patients with hemophilia A with and without inhibitors while introducing new challenges and increasing the complexity of clinical decision-making. Areas covered : Use of emicizumab can substantially delay initial exposure to FVIII thereby altering the natural history of inhibitor development, but it remains unclear whether later exposure to FVIII might modify the incidence of inhibitor development. Moreover, decisions regarding initiation of immune tolerance induction (ITI) therapy in patients with newly diagnosed inhibitors have become more complicated since emicizumab was introduced. Using emicizumab in lieu of ITI has implications such as precluding the use of FVIII for breakthrough bleeds and surgery, and possibly impacting on patients' future ability to receive gene therapy. Although bypassing agents are the mainstay of managing acute bleeds and surgery in inhibitor patients, their concomitant use with novel therapies can be difficult to manage/monitor. Evidence from the HAVEN clinical trials program suggests that minor surgeries in inhibitor patients can be performed with emicizumab alone, whereas major surgeries require the use of perioperative bypassing agents. Expert opinion : Until the long-term effects of non-replacement therapies become known, patients who develop inhibitors should continue to receive ITI.

Emicizumab, a bispecific humanized monoclonal antibody, bridges activated factor IX (FIX) and FX to restore the function of missing activated FVIII in hemophilia A. Emicizumab prophylaxis in children with hemophilia A and FVIII inhibitors was investigated in a phase 3 trial (HAVEN 2). Participants, previously receiving episodic/prophylactic bypassing agents (BPAs), were treated with subcutaneous emicizumab: 1.5 mg/kg weekly (group A), 3 mg/kg every 2 weeks (group B), or 6 mg/kg every 4 weeks (group C). Pharmacokinetics, safety, and efficacy (including an intraindividual comparison of participants from a noninterventional study) were evaluated. Eighty-five participants aged <12 years were enrolled. In group A (n = 65), the annualized rate of treated bleeding events (ABRs) was 0.3 (95% confidence interval [CI], 0.17-0.50), and 77% had no treated bleeding events. Intraindividual comparison of 15 participants who previously took BPA prophylaxis showed that emicizumab prophylaxis reduced the ABR by 99% (95% CI, 97.4-99.4). In groups B (n = 10) and C (n = 10), ABRs were 0.2 (95% CI, 0.03-1.72) and 2.2 (95% CI, 0.69-6.81), respectively. The most frequent adverse events were nasopharyngitis and injection-site reactions; no thrombotic events occurred. Two of 88 participants developed antidrug antibodies (ADAs) with neutralizing potential, that is, associated with decreased emicizumab plasma concentrations: 1 experienced loss of efficacy, and, in the other, ADAs disappeared over time without intervention or breakthrough bleeding. All other participants achieved effective emicizumab plasma concentrations, regardless of the treatment regimen. Emicizumab prophylaxis has been shown to be a highly effective novel medication for children with hemophilia A and inhibitors. This trial was registered at www.clinicaltrials.gov as #NCT02795767., (© 2019 by The American Society of Hematology.)

Results from the main parts (24 weeks) of 2 concizumab phase 2 trials are presented: explorer4 in hemophilia A (HA) or B (HB) with inhibitors (HAwI/HBwI) and explorer5 in HA. The trials aimed to evaluate the efficacy of daily subcutaneous concizumab prophylaxis (evaluated as annualized bleeding rate [ABR] at last dose level), with secondary objectives being safety and immunogenicity (assessed as number of adverse events [AEs] and antidrug antibodies [ADAs]). Patients received 0.15 mg/kg concizumab, with potential dose escalation to 0.20 and 0.25 mg/kg (if ≥3 spontaneous bleeding episodes within 12 weeks of concizumab treatment). Relevant pharmacokinetic/pharmacodynamic (PK/PD) parameters were assessed. Thirty-six HA, 9 HAwI, and 8 HBwI patients were exposed to concizumab. Most inhibitor patients (15 of 17; 88.2%) did not escalate the dose; all patients chose to continue to the extension phase of the trials. Clinical proof of concept for prevention of bleeding episodes was demonstrated in both trials. Estimated ABRs in HAwI and HBwI were lower vs HA: 3.0 (95% confidence interval [CI], 1.7; 5.3) and 5.9 (95% CI, 4.2; 8.5) vs 7.0 (95% CI, 4.6; 10.7), respectively. PK/PD results were as expected, with no difference between hemophilia subtypes for concizumab exposure, free tissue factor pathway inhibitor, thrombin generation, prothrombin fragment 1+2, and d-dimers. Concizumab was safe and well tolerated (no severe AEs, AE-related withdrawals, or thromboembolic events). Three patients had (very low to medium titer) ADA+ tests in each trial, with no observed clinical effect. These results support further development of concizumab as a daily prophylactic treatment in all hemophilia patients. These trials were registered at www.clinicaltrials.gov as #NCT03196284 and #NCT03196297., (© 2019 by The American Society of Hematology.)

Haemophilia is a serious inherited bleeding disorder resulting from a deficiency of coagulation factor VIII (haemophilia A) or coagulation factor IX (haemophilia B). While effective therapies have been developed to replace the missing factor and restore normal coagulation, they can lead to the development of neutralizing anti-drug antibodies, termed inhibitors, which significantly worsen morbidity and quality of life. While advancements have been made to improve the management of patients, and particularly for this review, children with inhibitors, there remain significant unmet needs including inhibitor prevention, inhibitor eradication and, when those fail, more effective bleed prevention and a reduction in the treatment burden. This review will discuss current treatment options including the recently licensed bispecific antibody, emicizumab, and provide insights into how I treat children with inhibitors., (© 2019 British Society for Haematology and John Wiley & Sons Ltd.)

Introduction: As a result of the new treatment paradigm that the haemophilia community will face with the availability of novel (non-factor) therapies, an updated consensus on ITI recommendations and inhibitor management strategies is needed., Aim: The Future of Immunotolerance Treatment (FIT) group was established to contemplate, determine and recommend the best management options for patients with haemophilia A and inhibitors., Discussion and Conclusions: Despite the considerable success of emicizumab in the management of inhibitor patients, the FIT group still sees the importance of eradicating inhibitors. However, the availability of emicizumab and other non-factor therapies in the future might impact greatly on how ITI is undertaken. Theoretically, concomitant use of emicizumab and FVIII might allow emicizumab to effectively prevent bleeding with lower dose ITI regimens. This might allow for the greater adoption of low-dose/low-frequency FVIII ITI regimens, which may result in a reduced need for central venous access devices while still maintaining a reasonable likelihood of ITI success. The FIT group proposes a new management algorithm for current ITI (without emicizumab) and a hypothetical new approach with the availability of emicizumab. As there are no published data regarding the concomitant use of emicizumab and FVIII for ITI, the FIT Expert group encourages the undertaking of properly conducted prospective studies to explore these approaches further., (© 2019 The Authors. Haemophilia Published by John Wiley & Sons Ltd.)

Hemophilia A and B are inherited bleeding disorders characterized by deficiency or dysfunction of coagulation protein factors VIII and IX, respectively. Recurrent joint and muscle bleeds are the major clinical manifestations. Replacement therapy with clotting factors, either at the time of bleeding or as part of a prophylactic regimen, is adapted to individual patient needs. The major complication of therapy is the development of neutralizing antibodies. In response, researchers have developed novel agents to both reduce the treatment burden and prevent bleeding regardless of the presence of inhibitors. Another new development, gene therapy, has the potential for a definitive cure. This review summarizes the pathophysiology, clinical presentation, diagnosis, and treatment of hemophilia, as well as information regarding neutralizing antibodies, immune tolerance induction, novel agents, and gene therapy.

Hemophilia A and B are rare inherited bleeding disorders resulting from deficiency of coagulation factors VIII and IX respectively. In the past few decades, the field of hemophilia has witnessed pivotal management challenges and therapeutic advances. Routine coagulation and factor assays, while useful in the classification of severity and treatment monitoring in hemophilia patients, have been shown to be of limited use in managing clinical presentations and outcomes. This prompted the investigation of viscoelastic studies in hemophilia care, which have established their utility in various bleeding and thrombotic states. In this review, we will discuss and critically assess the current literature highlighting the use of viscoelastic studies in various aspects of hemophilia including the determination of clinical phenotype, management of patients with inhibitors, perioperative management, and monitoring of novel agents., (© 2018 Wiley Periodicals, Inc.)

Introduction: Persons with haemophilia A (PwHA) with inhibitors to factor VIII often experience decreased health-related outcomes. In HAVEN 1 (NCT02622321), there was a statistically significant reduction in bleeding with emicizumab prophylaxis versus no prophylaxis., Aim: Describe health-related outcomes in PwHA with inhibitors in HAVEN 1., Methods: PwHA with inhibitors aged ≥12 years previously on episodic bypassing agents (BPAs) were randomized to emicizumab prophylaxis (Arm A; n = 35) or no prophylaxis (Arm B; n = 18); participants previously on BPA prophylaxis received emicizumab prophylaxis (Arm C; n = 49). Health-related outcomes assessed at baseline and monthly thereafter: Haemophilia Quality of Life Questionnaire for Adults (Haem-A-QoL), Haemophilia-specific Quality of Life Questionnaire for Children Short Form (Haemo-QoL SF), EuroQol 5-Dimensions 5-Levels (EQ-5D-5L) index utility score (IUS) and visual analogue scale (EQ-VAS) and work/school days. Days hospitalized also recorded., Results: At week 25, differences (ANCOVA) in adjusted mean scores (95% confidence interval) favoured Arm A versus B for Haem-A-QoL "Total" score (14.0 [5.6, 22.5]; P = 0.002) and "Physical Health" (21.6 [7.9, 35.2]; P = 0.003); EQ-VAS (-9.7 [-17.6, -1.82]; P = 0.017); and IUS (-0.16 [-0.25, -0.07]; P = 0.001); mean scores are comparable in Arms A and C. Throughout the study, a greater proportion of participants on emicizumab prophylaxis than no prophylaxis exceeded questionnaire-specific responder thresholds. Mean proportion of missed work days and number of days hospitalized were lower with emicizumab prophylaxis than no prophylaxis., Conclusions: In PwHA with inhibitors, emicizumab prophylaxis was associated with substantial and meaningful improvements in health-related outcomes., (© 2018 John Wiley & Sons Ltd.)

The development of inhibitors against factor VIII (FVIII) concentrates represents a significant treatment complication for hemophilia. Immune tolerance induction (ITI) therapy eradicates inhibitors in 60-80% of patients, resulting in a normal FVIII response. This article, based on presentations at the 6th International Coagulation Meeting, held in Barcelona, Spain, in September 2017, provides an overview of management approaches for patients with inhibitors and briefly tabulates four cases of ITI therapy (first-line or rescue ITI therapy in pediatric and adult patients) with successful outcomes. Switching FVIII product from recombinant FVIII to plasma-derived FVIII/VWF concentrate may be helpful in eradicating inhibitors. The rate of decline of inhibitor titer in the initial stages of ITI therapy is a good indicator of the success or failure of therapy, although prognostic biomarkers are needed. The development of the bispecific monoclonal antibody emicizumab, which was recently shown to reduce bleeding in inhibitor patients, offers a potential alternative therapeutic option. However, the benefits of inhibitor eradication, including a wider choice of cheaper therapeutic products for preventing and treating bleeds, suggest that at least one attempt of ITI therapy should be offered to patients who develop inhibitors., (© 2019 S. Karger AG, Basel.)

Introduction: Hemophilia is a serious bleeding disorder characterized by repeated bleeding episodes into joints and muscles which can lead to permanent disabilities. Treatment with factor replacement therapy has proven to be effective at preventing these complications; however, it can lead to formation of neutralizing antibodies termed inhibitors which significantly complicate the management of the disorder. These inhibitor patients suffer from increased morbidity and mortality and there has been a major unmet need for novel therapeutic approaches. Recently, one such therapy, emicizumab, has been licensed in the United States. Areas covered: This manuscript contains a detailed discussion of the mechanism of action, the clinical trial development program as well as a review of the benefits and risks of this novel agent. In addition, practical considerations for the use of the agent are also described. Expert commentary: Emicizumab represents a new class of medication for the treatment of hemophilia A which in the past has relied on factor replacement therapy and bypassing agent (alternative factor) therapy. Emicizumab fulfills two major unmet needs in patients with hemophilia who have FVIII inhibitors. First, it provides for a much more effective therapy for the prevention of bleeding and second it substantially reduces the treatment burden.

Introduction: Inhibitors against factor VIII (FVIII), which develop in around 20-30% of patients with severe hemophilia A, represent a significant complication of on-demand or prophylactic FVIII therapy. Currently, the main treatment option for inhibitor patients is eradication using immune tolerance induction (ITI) therapy. Areas covered: This article reviews inhibitor eradication in clinically complicated hemophilia A patients. The benefits and disadvantages of ITI therapy are discussed, with reference to the new nonfactor replacement agents such as emicizumab, which are becoming available. Expert commentary: At present, ITI therapy is the method of choice for all inhibitor patients, but as alternative treatment options become increasingly available, this may change in the future. Despite the development of nonfactor replacement agents, ITI therapy is likely to maintain a key role in the management of inhibitor patients, although changes in ITI therapy regimens including the timing of ITI initiation, the dosing regimen, the management of thrombotic risk or safety, laboratory assessment of ITI outcomes, and maintenance treatment after ITI success, may be necessary.

Introduction: Although clinical trials have demonstrated extended half-life (EHL) VIII and IX fusion proteins to be safe and efficacious in patients with haemophilia A and B, studies on real-world clinical application have not been performed., Aim: To retrospectively examine the real-world experience of rFVIII Fc and rFIX Fc in patients., Methods: A retrospective review of existing medical records of patients with haemophilia A or haemophilia B who had been prescribed rFVIII Fc or rFIX Fc was conducted from the Children's Hospital Los Angeles Haemostasis and Thrombosis Centre database., Results: A total of 36 male subjects enroled in the study (17 patients with haemophilia A and 19 patients with haemophilia B; 0-18 years of age, N = 27; >18 years of age, N = 9). Patients had a reduction of their ABR and AJBR following initiation of EHL factors. For patients with haemophilia A, the ABR and ABJR fell from 2.3 and 1.8 to 1.3 and 0.71, respectively. For patients with haemophilia B, the ABR and ABJR fell from 2.5 and 2.1 to 0.82 and 0.37, respectively. Five of 36 patients reverted from EHL back to standard half-life (SHL) factor treatment. Overall, treatment with EHL factors reduced factor consumption by nearly half compared to treatment with SHL factors in patients with haemophilia B., Conclusion: This study demonstrates the largely successful transition of 36 patients from SHL to EHL factor products., (© 2018 John Wiley & Sons Ltd.)

Introduction: The development of inhibitors against factor VIII (FVIII) replacement therapy remains the most important challenge for clinicians in the treatment of hemophilia patients. This review focusses on risk factors and management of FVIII inhibitors, particularly in light of SIPPET study findings and subsequent analyses. Areas covered: A brief history and evolution of hemophilia therapies is provided, including an overview of conventional and new (including investigational) therapeutic approaches for the treatment of hemophilia. The SIPPET study, the first randomized clinical trial to demonstrate a lower incidence of inhibitors in previously untreated patients treated with plasma-derived FVIII products compared with recombinant FVIII products, has generated much debate. We review the SIPPET trial and reactions, in addition to preliminary observations from a single center's experience, the cost impact of inhibitors, recent findings from SIPPET subanalyses, and inhibitor development in previously-treated patients. Expert commentary: Despite recent advances in potential new treatment options for hemophilia, conventional factor replacement concentrates currently remain the cornerstone of treatment. It is paramount that clinicians familiarize themselves with the findings from the SIPPET trial and substudies, in order to better inform their patients and families on inhibitor risk factors and to aid the treatment decision-making process.

Self-administration of factor and bypassing agents by persons with hemophilia in the home setting is recommended to facilitate earlier intervention after bleeding episodes. The objective of this review was to summarize recombinant activated coagulation factor VII (rFVIIa) safety and efficacy data from clinical trials and patient registries documenting use in the home treatment setting in people with congenital hemophilia with inhibitors (CHwI). A total of 16 studies and registries were identified for inclusion; 14 evaluated on-demand treatment of acute bleeding episodes (865 patients, 9024 bleeding episodes) and 2 evaluated use for secondary prophylaxis (108 patients, 42,861 prophylaxis days). In the on-demand studies, efficacy was consistently high (81%-96%), and thrombotic events were uncommon (n = 3). In the secondary prophylaxis studies, rFVIIa was associated with a 45% to 59% reduction in bleeding episodes and no thrombotic events. These data support the clinical practice of administering rFVIIa in patients in the home treatment setting after initiation under a physician's care., (© 2017 Wiley Periodicals, Inc.)

Background: Emicizumab (ACE910) bridges activated factor IX and factor X to restore the function of activated factor VIII, which is deficient in persons with hemophilia A. This phase 3, multicenter trial assessed once-weekly subcutaneous emicizumab prophylaxis in persons with hemophilia A with factor VIII inhibitors., Methods: We enrolled participants who were 12 years of age or older. Those who had previously received episodic treatment with bypassing agents were randomly assigned in a 2:1 ratio to emicizumab prophylaxis (group A) or no prophylaxis (group B). The primary end point was the difference in bleeding rates between group A and group B. Participants who had previously received prophylactic treatment with bypassing agents received emicizumab prophylaxis in group C., Results: A total of 109 male participants with hemophilia A with inhibitors were enrolled. The annualized bleeding rate was 2.9 events (95% confidence interval [CI], 1.7 to 5.0) among participants who were randomly assigned to emicizumab prophylaxis (group A, 35 participants) versus 23.3 events (95% CI, 12.3 to 43.9) among those assigned to no prophylaxis (group B, 18 participants), representing a significant difference of 87% in favor of emicizumab prophylaxis (P<0.001). A total of 22 participants in group A (63%) had zero bleeding events, as compared with 1 participant (6%) in group B. Among 24 participants in group C who had participated in a noninterventional study, emicizumab prophylaxis resulted in a bleeding rate that was significantly lower by 79% than the rate with previous bypassing-agent prophylaxis (P<0.001). Overall, 198 adverse events were reported in 103 participants receiving emicizumab prophylaxis; the most frequent events were injection-site reactions (in 15% of participants). Thrombotic microangiopathy and thrombosis were reported in 2 participants each (in the primary analysis) who had received multiple infusions of activated prothrombin complex concentrate for breakthrough bleeding. No antidrug antibodies were detected., Conclusions: Emicizumab prophylaxis was associated with a significantly lower rate of bleeding events than no prophylaxis among participants with hemophilia A with inhibitors. (Funded by F. Hoffmann-La Roche and Chugai Pharmaceutical; HAVEN 1 ClinicalTrials.gov number, NCT02622321 .).

Background: Prophylactic replacement with factor concentrate is the optimal treatment for persons with severe haemophilia to avoid or minimize bleeding. This ultimately prevents or reduces joint disease and improves life expectancy and quality of life towards values matching those in the normal population. However, uncertainty still exists around the optimal regimens to be prescribed for prophylaxis. An increasing number of treating physicians and patients are showing interest in patient-tailored approaches to prophylaxis, which aim to harmonize the prophylaxis regimen with the patients' bleeding phenotype, levels of physical activity and a variety of other variables., Methods: A modified Delphi technique was adopted to generate consensus. The expert panel met in person to set the objectives, be trained on the Delphi technique and agree on the desired level of consensus. Three iterations were used to identify the targets, the scenarios and their combinations., Results: Twenty-eight scenarios and eight target levels were identified and used to issue recommendations. The panel reached the desired level of consensus on positive or negative recommendations. Areas where consensus was not reached were identified and proposed as areas for future research. Prospective assessment of the validity of most of the proposed targets is recommended., Conclusions: We have generated, by expert consensus, target plasma levels of factor concentrate to be used to tailor treatment for persons with haemophilia., (© 2017 John Wiley & Sons Ltd.)