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Abstract: Coagulation factor IX plays a central role in hemostasis through interaction with factor VIIIa to form a factor X-activating complex at the site of injury. The absence of factor IX activity results in the bleeding disorder hemophilia B. This absence of activity can arise either from a lack of circulating factor IX protein or mutations that decrease the activity of factor IX. This review focuses on analyzing the structure of factor IX with respect to molecular mechanisms that are at the basis of factor IX function. The proteolytic activation of factor IX to form activated factor IX(a) and subsequent structural rearrangements are insufficient to generate the fully active factor IXa. Multiple specific interactions between factor IXa, the cofactor VIIIa, and the physiological substrate factor X further alter the factor IXa structure to achieve the full enzymatic activity of factor IXa. Factor IXa also interacts with inhibitors, extravascular proteins, and cellular receptors that clear factor IX(a) from the circulation. Hemophilia B is treated by replacement of the missing factor IX by plasma-derived protein, a recombinant bioequivalent, or via gene therapy. An understanding of how the function of factor IX is tied to structure leads to modified forms of factor IX that have increased residence time in circulation, higher functional activity, protection from inhibition, and even activity in the absence of factor VIIIa. These modified forms of factor IX have the potential to significantly improve therapy for patients with hemophilia B., (© 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: Few studies have evaluated direct medical or societal costs of haemophilia in the United Kingdom (UK), and how patient characteristics impact future costs is uncertain. Cost predictors were identified and examined using cross-sectional data from the CHESS I and II studies., Methods: Patient- and physician-reported outcomes were analysed for UK adult males aged ≤ 65, with haemophilia A or B and no recent clinical trial participation. Demographics, haemophilia type and severity, inhibitors, annual bleed rate (ABR), problem joints (PJs), treatment type, and comorbidities, were utilised in regression analyses. Health-related quality of life was assessed using EQ-5D. Generalised linear models estimated expected non-drug haemophilia-related direct medical costs (DMC) and societal costs (non-drug DMC, direct non-medical and indirect costs). Average marginal effects (AMEs) determined predictors of cost., Results: Costs for 378 patients were analysed. Mean age was 33 years and 79% (299) had haemophilia A. Mean annual per-patient DMC were £165,001 (including factor treatment costs) and £4,091 when excluding factor replacement treatment costs (non-drug DMC). Mean annual per-patient non-treatment societal costs were £11,550 (standard deviation £20,171) among those with data available (n = 51). Number of PJs, ABR, and treatment regimen were significant determinants of haemophilia-related non-drug DMC (all P < 0.001). Non-drug DMC increased as ABR increased (AMEs were £2,018 for ABR 1-5, £3,101 for ABR 6-10 and £5,785 for ABR ≥ 11, vs. ABR 0) and by £1,869 per additional PJ. No significant predictors of non-drug haemophilia-related societal costs were identified. Mean EQ-5D score was 0.66, with lower scores observed for people with haemophilia B (0.48) compared with haemophilia A (0.71) and with increasing haemophilia severity., Conclusions: UK direct medical and societal costs of haemophilia are substantial. Non-drug DMC were particularly associated with ABR and number of PJs. These findings may be useful for real-world evaluations of the economic burden of haemophilia in the UK., Competing Interests: Declarations Ethics approval and consent to participate The CHESS I and CHESS II studies were approved by the Research Ethics Sub Committee of the Faculty of Health and Social care within the University of Chester and conducted in correspondence with regional and relevant guidelines. Patient consent for use of clinical data was not required (as per European Pharmaceutical Market Research Association [EPhMRA] guidelines). Patient consent was obtained via tick box selection for the patient-reported element of the studies. Consent for publication Not applicable. Competing interests This study was sponsored by Pfizer Ltd. TB and EFG are employees of HCD Economics Ltd., which was a paid consultant to Pfizer Ltd. in connection with the development of this manuscript and for study design, data analysis and interpretation. EFG: Speakers’ bureau: Sobi, Roche, Novo Nordisk, BioMarin, CSL Behring; Advisory boards: Sobi, Roche, BioMarin, Pfizer. IW and LR are employees of Pfizer Ltd., the study sponsor. JOH was an employee of HCD Economics Ltd. during the conduct of the study. IW, AC, JB and LR were employees of Pfizer Ltd. during the conduct of this study. JB is currently employed by BioMarin Pharmaceutical Inc. ML was a paid consultant to Pfizer Ltd. in relation to study design and data interpretation for this study and also declares the following: Consultant to AstraZeneca, Silence, Hemab; Research grant support from BioMarin; Speaker fees from Pfizer, Bayer, Takeda, Leo Pharma, Sobi, AstraZeneca, Chugai/Roche; Advisory boards: Takeda, LFB, Roche/Chugai, Sobi, Bayer, Pfizer, CSL Behring, BioMarin. JG was a paid consultant to Pfizer Ltd. in relation to study design and data interpretation for this study and has been a paid consultant to HCD Economics Ltd. in relation to a separate haemophilia study., (© 2024. The Author(s).)

In hemophilia, deficiency of factor VIII or IX prevents the activation of the common coagulation pathway, and inhibits the conversion of FX to activated FXa, which is required for thrombin generation. We hypothesized that the direct expressed FXa has the potential to activate the common pathway and restore coagulation in hemophilia patients. In this study, the cassettes that expressed FXa, FXaop and FXa-FVII were packaged into an engineered AAV capsid, AAV843, and were delivered into hemophilia A and B mice by intravenous injection. AAV-FXaop could be stably expressed in vivo and showed the best immediate and prolonged hemostatic effects, similar to those of commercial drugs (Xyntha and Benefix). AAV-FXaop also significantly inhibited bleeding in hemophilia A mice with inhibitors. In addition, FXa expression in joints significantly alleviated the occurrence of hemophilic synovitis. AAV-delivered FXa may be a novel target for treating hemophilic and hemophilic synovitis., Competing Interests: Competing interests The authors declare no competing interests. Ethical approval All animals were kept in a pathogen-free environment and fed ad libitum. The procedures for the care and use of animals were approved by the Ethics Committee of the East China University of Science and Technology (NO. ECUST-2020-04033), and all applicable institutional and governmental regulations concerning the ethical use of animals were followed., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Background: Gene therapy is designed to provide people with hemophilia B with a steady and elevated factor (F)IX activity, thereby strengthening protection and relieving the burden of frequent replacement therapy infusions. The European Medicines Agency has approved gene therapy for the severe and moderately severe forms of hemophilia B that uses the FIX-Padua variant (etranacogene dezaparvovec)., Objectives: The aim was to provide a document dedicated to hemophilia B gene therapy and give a comprehensive overview of the topic., Methods: An Italian group of experts in hemophilia carried out a narrative review of the literature and discussed during a virtual meeting several key aspects of the delivery of this treatment in Italy. The discussion covered the organizational model, the role of the multidisciplinary team, the laboratory surveillance, and the patient's journey, from the follow-up to the identification of safety issues and outcome measures., Results: This article highlights the need to follow the Hub and Spoke organizational model and sheds light on the role of each professional figure within the multidisciplinary teams to favor patient engagement, management, and retention. Moreover, this article stresses the need to perform laboratory tests for patient screening and follow-up and proposes a checklist to help patient identification. Finally, the needs of Italian hemophilia centers have been considered to ensure an efficient implementation of the care delivery model., Conclusion: It is crucial to ensure that centers are appropriately organized, equipped, and trained to adequately select patients, deliver the gene therapy, and perform follow-up., Competing Interests: Declaration of competing interests G.C. reports payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing, or educational events from Bayer, BIOVIIIx, CSL Behring, BioMarin, Sanofi, Novo Nordisk, Takeda, Kedrion, LFB, Grifols, Roche, Sobi, and uniQure and reports participation on data safety monitoring board or advisory board for Bayer, CSL Behring, BioMarin, Sanofi, Novo Nordisk, Takeda, Kedrion, LFB, Grifols, Pfizer, Roche, and uniQure. G.D.M. reports being a speaker or a member of a speaker bureau for BioMarin, Bayer, CSL Behring, Roche, Takeda, and Viatris Pharmaceuticals and consultant or ad hoc speaker/consultant for BioMarin, Bayer, Pfizer, Takeda, and Viatris Pharmaceuticals. P.S. reports being a speaker for Bayer, CSL Behring, Stago, uniQure, Werfen, and Pfizer. S.S. has acted as a consultant for CSL Behring, Amgen, Novartis, Novo Nordisk, Sobi, and Bayer. E.B. participated in advisory boards for Amgen, Novartis, CSL Behring, Bayer, Roche, and Sobi. V.L.M. is a member of the advisory board of Pfizer, CSL Behring, and BioMarin; is a speaker for Gore and Alfasigma; and received research grants from Gilead and travel grants from Sobi, Sanofi, and Takeda. A.L. has participated in speaker bureaus for BioMarin and CSL Behring. F.P. reports consulting for and being a member of advisory boards of CSL Behring, BioMarin, Roche, Sanofi, and Sobi and is a member of the speaker’s bureau or educational programs/symposia for Takeda/Spark. E.F.G. has participated in speaker bureaus and advisory boards for BioMarin, Sobi, and Roche e Novo Nordisk. A.C.M. declares that they have no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Objectives: We aimed to characterise baseline disease and treatment burden in a large population with haemophilia A/B, both with (HAwI/HBwI) and without (HA/HB) inhibitors., Methods: The prospective, non-interventional explorer6 study included patients ≥12 years old with severe HA, severe/moderate HB or HAwI/HBwI of any severity, treated according to local standard of care (excluding previous/current exposure to concizumab or emicizumab). Baseline characteristics and historical clinical data were collected and patient-reported outcomes, including treatment burden, were assessed., Results: The explorer6 study enrolled 231 patients with haemophilia (84 HAwI/HBwI) from 33 countries. At baseline, patients with HA/HB treated with prophylaxis had the lowest median annualised bleeding rates (ABRs; 2.0), irrespective of haemophilia type; of these patients, 27.5% (HA) and 31.4% (HB) had target joints. Patients with HAwI/HBwI treated episodically reported the highest treatment burden. Of these patients, 28.5% (HAwI) and 25.1% (HBwI) performed sports activities in the month before screening., Conclusion: Despite receiving routine clinical care, historical and baseline information from patients enrolled in explorer6 showed that patients with HA/HB treated episodically and patients with HAwI/HBwI had higher ABRs, higher treatment burden and participated in sports less than those with HA/HB treated with prophylaxis. Emerging treatments could be beneficial in addressing these unmet medical needs., (© 2024 The Author(s). European Journal of Haematology published by John Wiley & Sons Ltd.)

Abstract: Despite numerous efforts to raise awareness, many hemophilia carriers and female persons with hemophilia (PWHs) remain undiagnosed. Between May 2021 and April 2023, we identified potential and obligate carriers of hemophilia A (HA) and hemophilia B (HB) by updating pedigrees of all PWHs followed at the Cliniques universitaires Saint-Luc, Brussels. Retrospective data on previously screened females were collected, including bleeding history, coagulation factor levels, and testing for the proband's pathogenic variant. In addition, a proactive approach involved sending 125 invitation letters to unscreened or incompletely screened individuals, through related PWHs. In pedigrees of 287 male PWHs (226 HA and 61 HB) and 7 female index patients from 236 families (184 HA and 52 HB), a total of 900 female individuals were identified. Of those, 454 were obligate and/or genetically proven carriers, and 118 were noncarriers. Genetic testing was conducted in 133 obligate, 237 potential, and 4 sporadic carriers, with 190 obligate and 328 potential carriers remaining untested. Among carriers with known factor levels (261/454), 42 HA (23.0%) and 23 HB carriers (29.5%) had a factor level <40 IU/dL. Carriers with a factor deficiency were screened on average 6 years earlier than other females (P = .034). This study, to our knowledge, represents the first systematic effort to identify potential carriers among families of all PWHs within a single center, emphasizing the challenges in comprehensive screening for female individuals genetically linked to one or more PWHs. Such initiatives are vital for achieving equitable access to hemophilia care for all potentially affected individuals, irrespective of gender. This trial was registered at www.ClinicalTrials.gov as #NCT05217992., (© 2024 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.)

Objective: To evaluate the level of care available for haemophilia patients., Methods: The descriptive, retrospective analytical study was conducted from December 15, 2020, to March 1, 2021, after approval from the Mustansiriyah University, Baghdad, Iraq, and comprised data from 3 haemophilia treating centres in Iraq participating in the World Bleeding Disorders Registry. The data collected related to patients with haemophilia A and B enrolled in the registry since March 2018, and included age at diagnosis, type of haemophilia, disease severity, age at first bleed and at first joint bleed, type of replacement therapy and outcome. Data was analysed using statistical package of social sciences (SPSS) version 20., Results: Of the 638 patients with mean age 16.2±4.3 (range: 9-29 years), 581(91%) had haemophilia A, 57(8.9%) had haemophilia B, 385(60.5%) had severe haemophilia, 126(19.8%) moderate and 125(19.7%) mild. Further, 259(41%) patients had been diagnosed for <1 year. There were 1354 bleeding events, and haemarthrosis accounted for 959(70.8%) of them. The mean annualised bleeding rate for severe patients was 2 ± 0.6(range 0-4), while the mean annualised joint bleeding rate was 4 ± 1.3(range :2-8). There were 256(32.3%) patients who were tested for inhibitors, and 62(24.3%) were positive. Among 426(73.3%) haemophilia A patients with a treatment history, 248(58%) were on prophylactic therapy, and the corresponding value among 37(65%) haemophilia B patients was 17(46%)., Conclusions: Access to treatment was found to be limited, and patients were found to be suffering from high bleeding rates and joint damage.

Background: In 2022-2023, the US Food and Drug Administration approved 2 novel gene therapies, valoctocogene roxaparvovec and etranacogene dezaparavovec, for hemophilia A and B, respectively. These one-time-administered gene therapies have been marketed at prices that create financial challenges for payers and patients. Understanding the magnitude and uncertainties around the long-term value of these therapies and how they can potentially relate to managed care practices is of high interest to the payer and patient community., Objective: To conduct a systematic review of cost-effectiveness analysis (CEA) studies to assess (1) the long-term value of valoctocogene roxaparvovec and etranacogene dezaparavovec and (2) the relevance and validity of the underlying data and assumptions used in the CEA models and discuss how they relate to the challenges identified for CEAs of gene therapies., Methods: A systematic review of cost-effectiveness studies of novel hemophilia A and B gene therapy was conducted. PubMed and Embase were searched for published studies from inception to January 12, 2024. Original research articles published in English that conducted a CEA on gene therapy treatments for hemophilia A and B, with a comparison of incremental costs and health effects, were considered. Critical appraisal of the quality of reporting and the underlying modeling assumptions were conducted to assess the relevance and validity of the results., Results: Two hundred thirty-eight studies were identified, of which 4 met the inclusion criteria. Three studies were conducted from a US health care perspective and 1 from a Dutch societal perspective. Despite the high upfront costs of the gene therapies, all included studies' (3 hemophilia A and 1 hemophilia B) modeled results showed that gene therapies had lower overall costs and better health outcomes compared with factor concentrate replacement therapies and emicizumab. The results were driven by the assumption that gene therapies will have a durable effect of at least 10 years and offset the high cost of the current standard of care. The modeled health improvements varied substantially across studies, showing that the long-term value is sensitive to varying clinical and economic assumptions., Conclusions: The novel hemophilia gene therapy treatments can potentially be a cost-effective use of treatment resources if the treatment effects are durable over time. To reduce the risk for payers while still facilitating patient access, outcomes-based agreements similar to what has recently been proposed by the Centers for Medicare & Medicaid Services for sickle-cell therapies are well supported.

Background:  Fidanacogene elaparvovec, an adeno-associated virus-based gene therapy vector expressing the high-activity factor IX (FIX) variant FIX-R338L, is in development for hemophilia B. One-stage clotting (OS) assays and chromogenic substrate (CS) assays are commonly used to measure FIX-R338L variant activity. Data from ongoing trials suggest FIX activity varies between different OS and CS assays., Material and Methods:  To better understand FIX-R338L activity in clinical samples, an international multisite field study was conducted across a central laboratory and 18 local laboratories, using standard protocols, reagents, and instrumentation, with individual participant samples from a phase 1/2a study of fidanacogene elaparvovec., Results:  Unlike the wild-type FIX control, FIX-R338L activity was higher with the OS silica-based assay versus OS ellagic acid-based and CS assays. Variation in FIX activity was greater at the lowest activity levels. Activated FIX (FIXa) in plasma could result in higher OS assay activity or increased thrombin generation, which could overestimate FIX activity. However, FIXa was not detected in the participant samples, indicating that it was not contributing to the OS assay differences. Since individuals on gene therapy may receive exogenous replacement FIX products, replacement products were spiked into patient plasma samples to target a therapeutic concentration. Exogenous FIX was additive to endogenous FIX-R338L, with no interference from FIX-R338L., Conclusion:  These results demonstrate FIX-R338L activity can be measured with OS and CS assays in clinical laboratories and provide insight into assay variability when measuring FIX with endogenously produced FIX-R338L. The findings may help establish best practices for measuring FIX-R338L activity (Clinicaltrials.gov identifier: NCT02484092)., Competing Interests: C.C., J.M., C.Y.T., J.Z.L., P.G., and J.R. are employees of Pfizer and may own stock/options in the company. D.D.P., H.S., S.R., J.-C.M., and J.E.M. were employees of Pfizer at the time of the study conduct and may own stock/options in the company., (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/).)

Hemophilia B is an inherited hemorrhagic disorder characterized by a deficiency of blood coagulation factor IX (FIX) that results in abnormal blood coagulation. The blood coagulation is already evident in hemophiliacs at the fetal stage, and thus intracranial hemorrhage and other bleeding complications can occur at birth, leading to sequelae. Therefore, it is important to develop effective treatments for hemophiliacs in utero. In this study, in order to transplacentally deliver FIX from pregnant mice to their fetuses, an improved adenovirus (Ad) vector expressing human FIX fused with the IgG Fc domain (FIX Fc fusion protein), which plays a crucial role in neonatal Fc receptor (FcRn)-mediated transcytosis across the placenta, was intravenously administered to E13.5 pregnant mice. Significant levels of FIX Fc fusion protein were detected in 0-day-old newborn mice whose mothers were administered an Ad vector expressing FIX Fc fusion protein. Wild-type FIX overexpressed in the pregnant mice was not delivered to the fetuses. Plasma FIX levels in the newborn mice were relatively well correlated with those in their mothers, although transplacental delivery efficiencies of FIX Fc fusion protein were slightly reduced when the FIX Fc fusion protein was highly expressed in the mother mice. Plasma FIX levels in the newborn mice were about 3.6-6.4% of those in their mothers, Transplacental delivery of FIX Fc fusion protein to their fetuses successfully improved the blood clotting ability in the newborn mice., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Background: Fidanacogene elaparvovec, an adeno-associated virus (AAV) gene-therapy vector for hemophilia B containing a high-activity human factor IX variant (FIX-R338L/FIX-Padua), was associated with sustained factor IX activity in a phase 1-2a study., Methods: We conducted a phase 3 open-label study of fidanacogene elaparvovec at a dose of 5×10 11 vector genome copies per kilogram of body weight. Men 18 to 65 years of age with hemophilia B and a factor IX level of 2% or less were eligible for screening if they had received at least 6 months of therapy with prophylactic factor IX concentrate. The primary end point, tested for noninferiority, was the annualized bleeding rate (treated and untreated bleeding episodes) from week 12 to month 15 after treatment with fidanacogene elaparvovec as compared with the prophylaxis lead-in period. Superiority, additional efficacy end points, and safety were also assessed., Results: Of 316 men who underwent screening for the lead-in study, 204 (64.6%) were not eligible; 188 (59.5%) of those were ineligible owing to the presence of anti-AAV neutralizing antibodies. Of the 45 participants who received fidanacogene elaparvovec, 44 completed at least 15 months of follow-up. The annualized rate of bleeding for all bleeding episodes decreased by 71%, from 4.42 (95% confidence interval [CI], 1.80 to 7.05) at baseline to 1.28 (95% CI, 0.57 to 1.98) after gene therapy, a treatment difference of -3.15 episodes (95% CI, -5.46 to -0.83; P = 0.008). This result shows the noninferiority and superiority of fidanacogene elaparvovec to prophylaxis. At 15 months, the mean factor IX activity was 26.9% (median, 22.9%; range, 1.9 to 119.0) by one-stage SynthASil assay. A total of 28 participants (62%) received glucocorticoids for increased aminotransferase levels or decreased factor IX levels (or both) starting between 11 and 123 days. No infusion-related serious adverse events, thrombotic events, development of factor IX inhibitors, or malignant conditions were observed., Conclusions: Fidanacogene elaparvovec was superior to prophylaxis for the treatment of participants with hemophilia B, leading to reduced bleeding and stable factor IX expression. (Funded by Pfizer; BENEGENE-2 ClinicalTrials.gov number, NCT03861273.)., (Copyright © 2024 Massachusetts Medical Society.)

Competing Interests: Declaration of competing interests The authors declare the following conflicts of interest (past 36 months): F.N.A.: member of the International Society on Thrombosis and Haemostasis (ISTH) Council and Vice-Chair of the ISTH Guideline and Guidance Committee; research funding (investigator-initiated studies, paid to university) from Bayer, Daiichi-Sankyo, and Sanofi; and consultancy fees (paid to university) from Boston Scientific. D.D.M.: member of the ISTH Council and consultant to the National Bleeding Disorders Foundation, the American Society of Hematology, and Believe Ltd on matters related to future research and workforce development in the areas of hematology and inherited bleeding disorders. A.C.: serves on the advisory board of Novo Nordisk and has received honoraria from Novo Nordisk, Grifols, Takeda, and Roche. E.V.D.P.: medical consultant for the area of the Brazilian Ministry of Health responsible for the national program of hereditary bleeding disorders. S.M.: member of the ISTH Council and reports participation in advisory or educational activities with AbbVie, Bayer, Astra Zeneca, Alveron (Advisory Board), Hemab, Norgine, Sanofi, Synapse, and Viatris; all honoraria are being paid to her institution. Y.F.-Y, T.S., and C.S. report no conflict of interest.

Aims/Background Reliable health-related quality of life data are critical in developing countries, in order to advocate for government agencies to develop national hemophilia care programmes. This study aims to explore the current status and influencing factors of health-related quality of life among adolescents with hemophilia in Hubei Province, so as to provide empirical data for professionals. Methods A total of 84 children with hemophilia aged 8 to 18, who were registered in Tongji Hemophilia Treatment Center and Hubei Hemophilia Home, were selected using a cluster sampling method. The "General Situation Questionnaire of Hemophiliac Adolescents", designed by Tongji Hemophilia Treatment Center, and "the Chinese version of Canadian hemophilia outcomes-kid's life assessment tool (CHO-KLAT)", were used for this study conducted from June 1, 2022 to December 30, 2022. Results 82 completed questionnaires were included. The average age of the 82 adolescents was 13.04 ± 3.29 years and all were males. Among them, 67 were hemophilia A and 15 were hemophilia B. 61 cases were severe type, 19 were moderate type and 2 cases were mild type. The average total score of the CHO-KLAT for adolescents with hemophilia in Hubei Province was 49.49, which was lower than their counterparts in developed countries. The statistically significant influencing factors included residence, annual family income, and disease type. Conclusion This study provides empirical data support for the health management of adolescents with hemophilia, highlighting the importance of improving medical resource access, transfusion convenience, and psychological support in enhancing the quality of life for this group. The results emphasize the need for healthcare systems and policymakers to take specific measures to address these factors to improve the treatment and care conditions for adolescents with hemophilia.

Objective: To review efficacy and safety data of valoctocogene roxaparvovec (Roctavian) and etranacogene dezaparavovec (Hemgenix), novel gene therapies for the treatment of the life-threatening bleeding disorders hemophilia A and B, respectively., Data Sources: A PubMed/Google Scholar search from inception through August 11, 2023 was conducted using the following keywords: gene therapy , hemophilia A , hemophilia B , etranacogene dezaparavovec , valoctocogene roxaparvovec , and bleeding., Study Selection and Data Extraction: Data, including phase 1 to 3 clinical trials (non-comparator), were obtained from primary literature and package inserts. These reports evaluated clinical pharmacology, efficacy, safety, adverse events, warnings, and precautions., Data Synthesis: Valoctocogene phase 3 study in males (n = 134): 87% had factor VIII (FVIII) levels that at least met criteria for mild hemophilia. Etranacogene phase 3 study in males (n = 54): within 3 weeks of infusion, mean factor IX (FIX) levels had reached 26.8 IU/dL. Both therapies provided clinically and statistically significant decreases in bleeding events and prophylactic factor infusions. Most common adverse event was elevations in liver function tests that were treated with glucocorticoids., Relevance to Patient Care and Clinical Practice in Comparison With Existing Drugs: The endogenous production of clotting factors mimics physiological production while decreasing morbidity and mortality related to bleeding events similar to the effects of existing replacement strategies. Gene therapy was also shown to increase patient quality of life., Conclusion: Valoctocogene and etranacogene provide another treatment for selected patients with hemophilia. Treatment for the patient with hemophilia (gene therapy vs replacement strategy) must be personalized as new clinical data are published being cognizant of drug affordability., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Etranacogene dezaparvovec is a recently approved gene therapy for people with hemophilia B (PwHB). Current standard of care is prophylaxis with factor IX (FIX) to prevent bleeding. Etranacogene dezaparvovec increases blood FIX levels such that FIX prophylaxis could be eliminated., Objective: To estimate the budgetary impact of etranacogene dezaparvovec adoption and utilization in a commercial health plan of the United States., Methods: A budget impact model was developed to evaluate the introduction of etranacogene dezaparvovec to treat severe or moderately severe hemophilia B. The model considered a hypothetical 1-million-member plan over a 5-year horizon. FIX therapy prophylaxis use was estimated based on a weighted average of relevant brands using US market share data. A scenario of etranacogene dezaparvovec adoption/utilization was compared with one without etranacogene dezaparvovec utilization. Two etranacogene dezaparvovec uptake (market share growth) analyses were performed: one with gradual uptake and alternatively assuming all eligible PwHB received etranacogene dezaparvovec in year 1. The one-time cost of etranacogene dezaparvovec was assumed to be $3.5 million. Other costs (FIX prophylaxis, disease monitoring, bleed management, and adverse events) were estimated from published literature. All costs were in 2022 US dollars. Bleed and adverse event rates were sourced from the HOPE-B trial comparing etranacogene dezaparvovec to previous FIX therapy prophylaxis. The model estimated annual and per-member per-month costs over 5 years. Secondary analyses were performed considering a 10-year horizon., Results: In the 1-million-member health plan, an estimated 1.8 PwHB were eligible for treatment with etranacogene dezaparvovec. Gradual uptake of etranacogene dezaparvovec resulted in cumulative 5-year budget impact of $848,509 compared with a scenario without etranacogene dezaparvovec. In years 1-5, the incremental annual and per-member per-month costs ranged from $79,824 to $271,435 and from $0.007 to $0.023, respectively. In the alternative uptake analysis, etranacogene dezaparvovec became cost saving annually beginning in year 2 and cumulatively beginning in year 5, for a 5-year savings of $754,844. Secondary analyses over 10 years found both uptake analyses cost saving. Other scenarios considered did not affect results substantially., Conclusions: Introducing etranacogene dezaparvovec as treatment for PwHB would have a modest budget increase within 5 years after treatment but may become cost saving if all eligible PwHB were treated in year 1. Initiating PwHB on etranacogene dezaparvovec sooner may produce greater overall savings and earlier annual savings. Etranacogene dezaparvovec is a treatment option that may provide overall cost savings for US commercial health plans, which would increase as the plan size increases.

Background: Hemophilia B is an X-linked bleeding disorder caused by a mutation in the gene responsible for encoding coagulation factor IX (FIX). Gene therapy offers promising potential for curing this disease. However, the current method of relatively high dosage of virus injection carries inherent risks. The purpose of this study was to introduce a novel scAAV-DJ/8-LP1-hFIXco vector transduced human umbilical cord blood derived mesenchymal stem cells (HUCMSCs) as an alternative cell-based gene therapy to conventional gene therapy for Hemophilia B., Methods: The LP1-hFIXco gene structure was designed by us through searching the literature from NCBI and the scAAV-DJ/8-LP1-hFIXco vector was constructed by a commercial company. The HUCMSCs were cultivated in routine approach and transduced with scAAV-DJ/8-LP1-hFIXco vector. The human FIX activation system was employed for detection of hFIXco activity. The RNA and protein expression levels of the hFIXco were evaluated using PCR and western blot techniques. In animal studies, both NSG and F9-KO mice were used for the experiment, in which clotting time was utilized as a parameter for bleeding assessment. The immunohistochemical analysis was used to assess the distribution of HUCMSCs in mouse tissue sections. The safety for tumorigenicity of this cell-based gene therapy was evaluated by pathological observation after hematoxylin-eosin staining., Results: The transduction of HUCMSCs with the scAAV-DJ/8-LP1-hFIXco vector results in consistent and sustainable secretion of human FIXco during 5 months period both in vitro and in mouse model. The secretion level (hFIXco activity: 97.1 ± 2.3% at day 7 to 48.8 ± 4.5% at 5 months) was comparable to that observed following intravenous injection with a high dose of the viral vector (hFIXco activity: 95.2 ± 2.2% to 40.8 ± 4.3%). After a 5-month observation period, no clonal expansions of the transduced cells in tissues were observed in any of the mice studied., Conclusions: We have discovered a novel and safer HUCMSCs mediated approach potentially effective for gene therapy in hemophilia B., (© 2024. The Author(s).)

One of the well-known X-linked genetic disorders is hemophilia, which could be hemophilia A as a result of a mutation in the F8 (factor VIII) gene or hemophilia B as a result of a mutation in the F9 (factor IX) gene, leading to insufficient levels of the proteins essential for blood coagulation cascade. In patients with severe hemophilia, factor VIII or factor IX activities in the blood plasma are considerably low, estimated to be less than 1%. This is responsible for spontaneous or post-traumatic bleeding episodes, or both, leading to disease complications and death. Current treatment of hemophilia relies on the prevention of bleeding, which consists of expensive lifelong replacement infusion therapy of blood plasma clotting factors, their recombinant versions, or therapy with recombinant monoclonal antibodies. Recently emerged gene therapy approaches may be a potential game changer that could reshape the therapeutic outcomes of hemophilia A or B using a one-off vector in vivo delivery and aim to achieve long-term endogenous expression of factor VIII or IX. This review examines both traditional approaches to the treatment of hemophilia and modern methods, primarily focusing on gene therapy, to update knowledge in this area. Recent technological advances and gene therapeutics in the pipeline are critically reviewed and summarized. We consider gene therapy to be the most promising method as it may overcome the problems associated with more traditional treatments, such as the need for constant and expensive infusions and the presence of an immune response to the antibody drugs used to treat hemophilia.

Most invasive dental procedures elicit some degree of bleeding which ultimately leads to clotting and eventual hemostasis. However, patients with inherited coagulation disorders may exhibit prolonged or, in some cases, excessive bleeding requiring multiple perioperative interventions. Von Willebrand disease is the most common inherited coagulopathy and often manifests via easy bruising, epistaxis, or prolonged bleeding. Hemophilia A (factor VII) and B (factor IX) are factor deficiencies that are clinically indistinguishable and managed according to severity and the required dental treatment. Other coagulopathies are rare (ie, inheritance is autosomal recessive) and may only become evident in homozygotes or compound heterozygotes. Current lab values and medical consultation with the patient's hematologist are imperative prior to rendering invasive dental treatment. There are a myriad of sedation and general anesthesia considerations, including risks for epistaxis with nasal instrumentation and bruising with improper patient positioning. Preoperative treatment with desmopressin or factor replacement may be required and generally should facilitate normal hemostasis. Additional therapies should be considered to help ensure adequate postoperative hemostasis, including pressure dressings, resorbable clotting materials, laser therapy, and oral rinses.

We investigated long-term human coagulation factor IX (huFIX) expression of a novel variant when delivered into mice and rhesus macaques and compared transduction efficiencies using two different adeno-associated virus (AAV) capsids. In hemophilic mice injected with KP1-packaged recombinant AAV (rAAV) expressing the hyperactive FIX variant specific activity plasma levels were 10-fold or 2-fold enhanced when compared with wild-type or Padua huFIX injected mice, respectively. In rhesus macaques AAV-LK03 capsid outperformed AAV-KP1 in terms of antigen expression and liver transduction. Two animals from each group showed sustained low-level huFIX expression at 3 months after administration, while one animal from each group lost huFIX mRNA and protein expression over time, despite comparable vector copies. We investigated whether epigenetic differences in the vector episomes could explain this loss of transcription. Cut&Tag analysis revealed lower levels of activating histone marks in the two animals that lost expression. When comparing rAAV genome associated histone modifications in rhesus macaques with those in mice injected with the same vector, the activating histone marks were starkly decreased in macaque-derived episomes. Differential epigenetic marking of AAV genomes may explain different expression profiles in mice and rhesus macaques, as well as the wide dose response variation observed in primates in both preclinical and human clinical trials., Competing Interests: Declaration of interests K.P., G.B., and M.A.K. are inventors on patents used in this paper. G.B., L.K., and N.L.M. have commercial affiliations. G.B. and M.A.K. have stock and/or equity in companies with technology broadly related to this paper., (Copyright © 2024 The American Society of Gene and Cell Therapy. Published by Elsevier Inc. All rights reserved.)

Competing Interests: Declaration of interests The author is a founder of sAAVient Therapeutics, an AAV gene therapy company focused on human liver diseases, including hemophilia. He is an inventor on several issued and filed patents on recombinant AAV vectors that have been or are being licensed to various AAV gene therapy companies. Research in his laboratory is supported by Public Health Service grants from the National Institutes of Health, a grant from the Children’s Miracle Network, and support from the Kitzman Foundation.

Hemophilia A and B are rare X-linked genetic bleeding disorders due to a complete or partial deficiency in the coagulation factors VIII or IX, respectively. The main treatment for hemophilia is prophylactic and based on coagulation factor replacement therapies. These treatments have significantly reduced bleeding and improved the patients' quality of life. Nevertheless, repeated joint bleedings (hemarthroses), even subclinical hemarthroses, can lead to hemophilic arthropathy (HA). This disabling condition is characterized by chronic pain due to synovial inflammation, cartilage and bone destruction requiring ultimately joint replacement. HA resembles to rheumatoid arthritis because of synovitis but HA is considered as having similarities with osteoarthritis as illustrated by the migration of immune cells, production of inflammatory cytokines, synovial hypertrophy and cartilage damage. Various drugs have been evaluated for the management of HA with limited success. The objective of the review is to discuss new therapeutic approaches with a special focus on the studies that have investigated the potential of using mesenchymal stromal cells (MSCs) in the management of HA. A systematic review of the literature has been made. Most of the studies have focused on the interest of MSCs for the delivery of missing factors VIII or IX but in some studies, more insight on the effect of MSC injection on synovial inflammation or cartilage structure were provided and put in perspective for possible clinical applications., Competing Interests: Competing interests The authors declare no competing interests., (Copyright © 2024 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

It is crucial to develop a long-term therapy that targets hemophilia A and B, including inhibitor-positive patients. We have developed an Adeno-associated virus (AAV) based strategy to integrate the bypass coagulation factor, activated FVII (murine, mFVIIa) gene into the Rosa26 locus using Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 mediated gene-editing. AAV vectors designed for expression of guide RNA (AAV8-gRNA), Cas9 (AAV2 neddylation mutant-Cas9), and mFVIIa (AAV8-mFVIIa) flanked by homology arms of the target locus were validated in vitro. Hemophilia B mice were administered with AAV carrying gRNA, Cas9 (1 × 10 11 vgs/mouse), and mFVIIa with homology arms (2 × 10 11 vgs/mouse) with appropriate controls. Functional rescue was documented with suitable coagulation assays at various time points. The data from the T7 endonuclease assay revealed a cleavage efficiency of 20-42 %. Further, DNA sequencing confirmed the targeted integration of mFVIIa into the safe-harbor Rosa26 locus. The prothrombin time (PT) assay revealed a significant reduction in PT in mice that received the gene-editing vectors (22 %), and a 13 % decline in mice that received only the AAV-FVIIa when compared to mock treated mice, 8 weeks after vector administration. Furthermore, FVIIa activity in mice that received triple gene-editing vectors was higher (122.5mIU/mL vs 28.8mIU/mL) than the mock group up to 15 weeks post vector administration. A hemostatic challenge by tail clip assay revealed that hemophilia B mice injected with only FVIIa or the gene-editing vectors had significant reduction in blood loss. In conclusion, AAV based gene-editing facilitates sustained expression of coagulation FVIIa and phenotypic rescue in hemophilia B mice., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: PS, NK and GRJ have applied for patents on AAV technology for gene therapy and few technologies have been licensed. Other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Introduction: For people with haemophilia B (PwHB), bleeding may occur despite prophylaxis, negatively affecting health-related quality of life (HRQoL). The pivotal phase 3 HOPE-B trial investigating the adeno-associated virus gene transfer product, etranacogene dezaparvovec (EDZ), demonstrated sustained factor IX (FIX) activity and bleed protection in PwHB with baseline FIX levels ≤2%., Aim: Assess how EDZ affects HRQoL in HOPE-B trial participants., Methods: HRQoL was evaluated using generic and disease-specific patient reported outcomes (PROs) including the EQ-5D-5L and the Hem-A-QoL questionnaires. Mean domain and total scores were compared 6 months pre- and the first 2 years post-EDZ administration using repeated measures linear mixed models. The percentage of participants with minimal clinically important improvements in HRQoL was also evaluated., Results: Two years post-EDZ, there were nominally significant increases in the least squares (LS) mean score for the EQ-5D-5L Index Value (.04; p = .0129), reflecting better HRQoL. Nominally significant decreases in the LS mean scores, reflecting better HRQoL, were also found for the Hem-A-QoL total score (-6.0; p < .0001) and the Treatment (-13.94; p < .0001), Feelings (-9.01; p < .0001), Future (-6.45; p = .0004) and Work/School (-5.21; p = .0098) domains. The percentage of participants with ≥15-point improvement ranged from 45.83% (95% CI: 31.37%, 60.83%) for Treatment to 13.89% (95% CI: 4.67%, 29.50%) for Family Planning. Results were similar for Year 1., Conclusion: In conclusion, gene therapy with EDZ improved HRQoL in the first and second years in several Hem-A-QoL domains, including Treatment, Feelings, Work/School and Future domains, whereas improvement in other aspects of HRQoL were not demonstrated., (© 2024 CSL Behring and The Authors. Haemophilia published by John Wiley & Sons Ltd.)

Background: The healthcare systems in Asia vary greatly due to the socio-economic and cultural diversities which impact haemophilia management., Methods: An advisory board meeting was conducted with experts in haemophilia care from Asia to understand the heterogeneity in clinical practices and care provision in the region., Findings: The overall prevalence of haemophilia in Asia ranges between 3 and 8.58/100,000 patients. Haemophilia A was more prevalent as compared to haemophilia B with a ratio of around 5:1. There is under-diagnosis in the region due to lack of diagnosis, registries and/or lack of appropriate facilities in suburban areas. Most patients are referred to the haematologists by their families or primary care physicians, while some are identified during bleeding episodes. Genetic testing faces obstacles like resource constraints, services available at limited centres and unwillingness of patients to participate. Prophylaxis is offered for people with haemophilia (PWH) with a severe bleeding phenotype. Recombinant factors are approved in most countries across the region and are the preferred therapy. The challenges highlighted for not receiving a high standard of care include patients' reluctance to use an intravenous treatment, poor patient compliance due to frequency of infusions, budget constraints and lack of funding, insurance, availability and accessibility of factor concentrates. Prevalence of neutralizing antibodies ranged from 5% to 20% in the region. Use of immune tolerance induction and bypassing agents to treat inhibitors depends on their cost and availability., Conclusion: Haemophilia care in Asia has evolved to a great extent. However, some challenges remain for which a strategic approach along with multi-stakeholder involvement are needed., (© 2024 The Authors. Haemophilia published by John Wiley & Sons Ltd.)

Hemophilia is a genetic disorder that is caused by mutations in coagulation factor VIII (hemophilia A) or IX (hemophilia B) genes resulting in blood clotting disorders. Despite advances in therapies, such as recombinant proteins and products with extended half-lives, the treatment of hemophilia still faces two major limitations: the short duration of therapeutic effect and production of neutralizing antibodies against clotting factors (inhibitor). To overcome these limitations, new hemophilia treatment strategies have been established such as gene therapy, bispecific antibody, and rebalancing therapy. Although these strategies have shown promising results, it is difficult to achieve a permanent therapeutic effect. Advances in the clustered regularly interspaced short palindromic repeat (CRISPR) technology have allowed sustainable treatment by correcting mutated genes. Since genome editing generates irreversible changes in host genome, safety must be ensured by delivering target organs. Therefore, the delivery tool of the CRISPR system is crucial for safe, accurate, and efficient genome editing. Recently, non-viral vector lipid nanoparticles (LNPs) have emerged as safer tools for delivering CRISPR systems than other viral vectors. Several previous hemophilia pre-clinical studies using LNP-CRISPR showed that sufficient and sustainable therapeutic effects, which means that LNP-CRISPR-mediated genome-editing therapy can be a valid option for the treatment of hemophilia. In this paper, we summarize the latest advancements in the successful treatment of hemophilia and the potential of CRISPR-mediated genome-editing therapy using LNPs., (© 2024. The Author(s).)

Abstract: The US Food and Drug Administration (FDA)'s authorization of etranacogene dezaparvovec (Hemgenix) is a significant milestone, constituting not only the first FDA approval of a gene therapy for hemophilia but also the first approval of a liver-targeted adeno-associated virus vector gene therapy. This review summarizes the nonclinical studies and clinical development that supported regulatory clearance. Similar to other gene therapies for single gene disorders, both the short-term safety and the phenotypic improvement were unequivocal, justifying the modest-sized safety and efficacy database, which included 57 participants across the phase 2b (3 participants) and phase 3 (54 participants) studies. The most common adverse reactions included liver enzyme elevation, headache, flu-like symptoms, infusion-related reactions, creatine kinase elevation, malaise, and fatigue; these were mostly transient. One participant had hepatocellular carcinoma on a study-mandated liver ultrasound conducted 1 year after vector infusion; molecular analysis of the resected tumor showed no evidence of vector-related insertional mutagenesis as the etiology. A remarkable 96% of participants in the phase 3 trial were able to stop factor IX (FIX) prophylaxis, with the study demonstrating noninferiority to FIX prophylaxis in terms of the primary end point, annualized bleeding rate. Key secondary end points such as the annualized infusion rate, which declined by 97%, and the plasma FIX activity level at 18 months after infusion, with least squares mean increase of 34.3 percentage points compared with baseline, were both clinically and statistically significant. The FDA's landmark approval of Hemgenix as a pioneering treatment for hemophilia stands on the shoulders of >20 years of gene therapy clinical research and heralds a promising future for genomic medicines., (© 2024 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.)

Attempts to achieve a functional cure or amelioration of the severe X linked bleeding disorders haemophilia A (factor VIII deficiency) and haemophilia B (factor IX deficiency) using AAV-based vectors have been frustrated by immune responses that limit efficacy and durability. The immune responses include adaptive and innate pathways as well as cytokine mediated inflammation, especially of the target organ cells-hepatocytes. Immune suppression has only been partly effective in clinical trials at ameliorating the immune response and the lack of good animal models has delayed progress in identifying mechanisms and developing more effective approaches to controlling these effects of AAV gene transfer. Here we discuss the arguments for and against more potent immunosuppression to improve factor expression after AAV-mediated gene therapy., (© 2024 The Authors. Journal of Viral Hepatitis published by John Wiley & Sons Ltd.)

Competing Interests: MCO has received research grants for her institution or participated in clinical trials, or both, from BioMarin, Novo Nordisk, Pfizer, Roche, Sanofi, and Takeda; has participated as speaker or in advisory boards, or both, sponsored by Bayer, BioMarin, Novo Nordisk, Pfizer, Roche, Sanofi, and Takeda; has received travel support from BioMarin, Novo Nordisk, Sanofi, and Takeda; and is a member of the council for the Novo Nordisk Haemophilia Foundation.

Background: Etranacogene dezaparvovec, the first gene therapy approved for haemophilia B treatment, was shown to be superior to treatment with continuous prophylactic factor IX in terms of bleeding protection 18 months after gene therapy in a phase 3 trial. We report post-hoc 24-month efficacy and safety data from this trial to evaluate the longer-term effects of etranacogene dezaparvovec in individuals with haemophilia B., Methods: The phase 3 HOPE-B trial enrolled males aged 18 years or older with inherited haemophilia B, classified as severe (plasma factor IX activity level <1%) or moderately severe (plasma factor IX activity level ≥1% and ≤2%), with a severe bleeding phenotype and who were on stable continuous factor IX prophylaxis. Participants were treated with a single infusion of etranacogene dezaparvovec (2 × 10 13 genome copies per kg of bodyweight). The primary endpoint, reported previously, was non-inferiority of the annualised bleeding rate (ABR) during the 52 weeks following stable factor IX expression (defined as months 7-18 after treatment) versus an at least 6-month lead-in period in which participants received their usual continuous factor IX prophylaxis, and is updated here up to month 24. Additional, post-hoc efficacy analyses, including adjusted ABR, factor IX activity, participants within factor IX ranges, and factor IX use, and safety analyses were performed at 24 months after gene therapy. Data were analysed in the full analysis set, which comprised the 54 patients who received at least a partial dose of gene therapy. The trial is ongoing and is registered with ClinicalTrials.gov, number NCT03569891., Findings: The study began on June 27, 2018, and participants were treated between January, 2019, and March, 2020; the date of data cutoff was April 21, 2022. 54 adult males (40 White, two Asian, one Black or African American, 11 other or missing) received a single intravenous infusion of etranacogene dezaparvovec and were followed for a median of 26·51 months (IQR 24·54-27·99), after a lead-in period of 7·13 months (6·51-7·82). In the updated analysis comparing months 7-24 after gene therapy to the lead-in period, mean adjusted ABR significantly reduced from 4·18 to 1·51 (p=0·0002) for all bleeds and from 3·65 to 0·99 (p=0·0001) for factor IX-treated bleeds. During each 6-month period after gene therapy, at least 67% of participants experienced no bleeding (36 of 54 during months 0-6 and stable thereafter), compared with 14 (26%) of 54 during the lead-in period. 24 months after gene therapy, 1 (2%) participant had one-stage factor IX activity less than 5%, whereas 18 (33%) had factor IX activity more than 40% (non-haemophilia range), with mean factor IX activity stable and sustained at 36·7% (SD 19·0%). 52 (96%) of 54 participants expressed endogenous factor IX, remaining free of factor IX prophylaxis at month 24. No new safety concerns were identified and no treatment-related serious adverse events or treatment-related deaths occurred. The most common treatment-related adverse events were an increase in alanine aminotransferase (nine [17%] of 54 patients), headache (eight [15%]), influenza-like illness (seven [13%]), and an increase in aspartate aminotransferase (five [9%])., Interpretation: By providing durable disease correction throughout the 24 months after gene therapy, etranacogene dezaparvovec provides a safe and effective therapeutic option for patients with severe or moderately severe haemophilia B., Funding: uniQure and CSL Behring., Competing Interests: Conflicts of interest MC has received financial support for research from Anthos, Bayer, CSL Behring/uniQure, Novo Nordisk, and Roche; has received honoraria for lecturing or consultancy from Alexion/AstraZeneca, Bayer, CSL Behring, Daiichi Sankyo, Sobi, and Viatris, all paid to his institution; is a member of the gene therapy working group of the European Association for Haemophilia and Allied Disorders (EAHAD) and the European Reference Network (ERN) EuroBloodNet; and is chair of the working group thrombosis and haemostasis of the Dutch Society of Vascular Medicine (NVIVG), part of the Dutch Internist's Society (NIV). SWP has received consultancy fees from Apcintex, ASC Therapeutics, Bayer, BioMarin, CSL Behring, Equilibra Bioscience, GeneVentiv, HEMA Biologics, Freeline, LFB, Novo Nordisk, Pfizer, Regeneron/Intellia, Roche/Genentech, Sanofi, Takeda, Spark Therapeutics, and uniQure; has received research funding from Siemens; and holds a membership on a scientific advisory committee for GeneVentiv and Equilibra Bioscience. WM has received honoraria from Bayer, Biomarin, Biotest, CSL Behring, Chugai, Freeline, LFB, Novo Nordisk, Octapharma, Pfizer, Roche, Sanofi, Takeda/Shire, and uniQure. JA has received consultancy fees and speaker fees from BioMarin, Pfizer, Sparks, uniQure, CSL Behring, SOBI, Sanofi, Novo Nordisk, Bayer, Roche, Takeda/Shire, and Octapharm; and research grants from SOBI, Bayer, Takeda/Shire, and CSL Behring. MR has received research support from Bayer, BioMarin, CSL Behring, Genentech, Grifols, Hema Biologics, LFB, Novo Nordisk, Octapharma, Sanofi, Spark, Takeda, and uniQure; has received consultancy fees from Catalyst Biosciences, CSL Behring, Genentech, Hema Biologics, Kedrion, Novo Nordisk, Pfizer, Sanofi, Takeda, and uniQure; and sits on the board of directors for the Foundation for Women and Girls with Blood Disorders, and Partners in Bleeding Disorders. PvdV has received consultancy fees from Bayer. BE, KP, SLQ, NG, and PEM are employees of CSL Behring, and KP also holds shares in CSL Behring. FWGL has received research support from CSL Behring, Takeda, Sobi, and uniQure; is a consultant for uniQure, Sobi, Biomarin, and Takeda, from which the fees go to the institution; and was a member of the data safety and monitoring board for a study by Roche., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Early gene therapy clinical trials for the treatment of Haemophilia B have been instrumental to our global understanding of gene therapy and have significantly contributed to the rapid expansion of the field. The use of adeno-associated viruses (AAVs) as vectors for gene transfer has successfully led to therapeutic expression of coagulation factor IX (FIX) in severe haemophilia B patients. Expression of FIX has remained stable following a single administration of vector for up to 8 years at levels that are clinically relevant to reduce the incidence of spontaneous bleeds and have permitted a significant change in the disease management with reduction or elimination of the need for coagulation factor concentrates. These trials have also shed light on several concerns around AAV-mediated gene transfer such as the high prevalence of pre-existing immunity against the vector capsid as well as the elevation of liver transaminases that is associated with a loss of FIX transgene expression in some patients. However, this field is advancing very rapidly with the development of increasingly more efficient strategies to overcome some of these obstacles and importantly raise the possibility of a functional cure, which has been long sought after. This review overviews the evolution of gene therapy for haemophilia B over the last two decades., Competing Interests: Declaration of competing interest VM has no conflict of interest. ACN is a founder of, owns equity in and acts as a consultant for Freeline Therapeutics. In addition he holds a sponsored research agreement from Freeline Therapeutics and is an inventor on patents licenced to the company. ACN also holds Revenue Sharing Agreement with St Jude's hospital., (Copyright © 2024. Published by Elsevier Ltd.)

Background: Gene therapy (GT) has recently become a new therapeutic option for hemophilia A and B. However, patient levels of knowledge and attitudes toward it are poorly understood. A general lack of knowledge and education has been highlighted in previous studies. To date, no studies focused on patient attitudes toward GT, priorities, concerns, and information needs, nor how these factors might influence their willingness to accept it., Objectives: To evaluate knowledge and attitudes toward GT of an Italian cohort of patients with hemophilia., Methods: A questionnaire was administered to patients with hemophilia A and B to evaluate: (1) clinical data; (2) GT knowledge; (3) willingness to accept GT, perceived benefits and concerns, and information needs., Results: Eighty-five patients participated in the study; 64 with severe hemophilia A and 4 with severe hemophilia B. Participants appeared to know only general information on GT, but little about its detailed functioning. The avoidance of frequent infusions and the reduction of bleeding episodes seem to be the most relevant expected benefits. The possibility of failing or losing effectiveness of GT over time was the main concern. Regarding willingness to undergo GT, 54.4% of respondents gave a negative response, mainly due to fear that treatment will lose effectiveness over time, fear of side effects, and lack of GT knowledge. Greater knowledge increased the acceptability of this disruptive therapy among patients with severe hemophilia., Conclusion: Overall, Italian patients with hemophilia showed poor knowledge of GT. However, it seems that greater knowledge was associated with a greater willingness to have GT., Competing Interests: Declaration of competing interests F.P.: speaker fees for educational programs/symposia organized by Spark and Takeda. Advisory boards/consultant for Sanofi, Sobi, Roche, Biomarin, CSL Behring. I.C.: speaker fees for educational symposia organized by Spark. M.M., I.G., and G.P. have no conflicts of interest., (Copyright © 2024 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)

Background: Laboratory resurrection of ancient coagulation factor (F) IX variants generated through ancestral sequence reconstruction led to the discovery of a FIX variant, designated An96, which possesses enhanced specific activity independent of and additive to that provided by human p.Arg384Lys, referred to as FIX-Padua., Objectives: The goal of the current study was to identify the amino acid substitution(s) responsible for the enhanced activity of An96 and create a humanized An96 FIX transgene for gene therapy application., Methods: Reductionist screening approaches, including domain swapping and scanning residue substitution, were used and guided by one-stage FIX activity assays. In vitro characterization of top candidates included recombinant high-purity preparation, specific activity determination, and enzyme kinetic analysis. Final candidates were packaged into adeno-associated viral (AAV) vectors and delivered to hemophilia B mice., Results: Five of 42 total amino acid substitutions in An96 appear sufficient to retain the enhanced activity of An96 in an otherwise human FIX variant. Additional substitution of the Padua variant further increased the specific activity 5-fold. This candidate, designated ET9, demonstrated 51-fold greater specific activity than hFIX. AAV2/8-ET9 treated hemophilia B mice produced plasma FIX activities equivalent to those observed previously for AAV2/8-An96-Padua, which were 10-fold higher than AAV2/8-hFIX-Padua., Conclusion: Starting from computationally inferred ancient FIX sequences, novel amino acid substitutions conferring activity enhancement were identified and translated into an AAV-FIX gene therapy cassette demonstrating high potency. This ancestral sequence reconstruction discovery and sequence mapping refinement approach represents a promising platform for broader protein drug and gene therapy candidate optimization., Competing Interests: Declaration of competing interests H.C.B., G.D., S.N.G., C.B.D., H.T.S., K.A.K., and C.W.C. are inventors on patents and patent applications describing the ancestral FIX technology filed by Expression Therapeutics, Emory University, Children’s Healthcare of Atlanta, and Georgia Institute of Technology. C.B.D., H.T.S., and H.C.B. are inventors on liver-directed codon-optimization and promoter technology filed by Emory University and Children’s Healthcare of Atlanta. H.T.S. and C.B.D. are cofounders of Expression Therapeutics, Inc, and own equity in the company. H.C.B., G.D., and S.N.G. are employees of Expression Therapeutics, Inc and own equity in the company. Expression Therapeutics, Inc has obtained licenses for FIX-An96, liver codon-optimized FIX, and synthetic liver-directed promoter intellectual property. K.C.C., P.C.S., and G.M.B. declare no conflicts of interest. The terms of these arrangements have been reviewed and approved by Emory University in accordance with its conflict of interest policies., (Copyright © 2023 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)

Clinical trials of adeno-associated virus (AAV)-based gene therapy have made remarkable progress in recent years. We aimed to perform a systematic review and meta-analysis of the literature to assess the efficacy and safety of AAV-based gene therapy for hemophilia. We systematically searched the Web of Science, Embase, PubMed, and the Cochrane Database of Systematic Reviews databases, for clinical trials involving patients diagnosed with hemophilia and treated with AAV-mediated gene therapy. Data on the annualized bleeding rate (ABR), annualized infusion rate (AIR), the incidence of treatment-related adverse events (TRAEs), severe adverse events (SAEs), and alanine aminotransferase (ALT) elevation were extracted as our outcomes. A total of 12 articles from 11 clinical trials were selected from 868 articles for meta-analysis. Pooled analyses showed that AAV-based gene therapy in hemophilia patients reduced the number of bleeding events and the number of factor infusion events by an approximate average of 7 per year and 103 per year, respectively. Eighty percent, 18%, and 63% of hemophilia patients had elevated TRAE, SAE, and ALT levels, respectively. Moreover, subgroup analysis found a significant reduction in ABR and AIR 2-3 years after the therapy. Additional findings that were not pooled including coagulation factor activity are presented in the accompanying tables. Our analysis supported the efficacy and safety of AAV-mediated gene therapy for hemophilia, providing evidence for its application as a therapeutic option for widespread clinical use in hemophilia patients in the future.

Introduction and Aim: A national survey was initiated by representatives of French patients with haemophilia (AFH) and the French reference centre for haemophilia, in order to appreciate the awareness and knowledge of these patients regarding haemophilia gene therapy (HGT) and understand better their position about this innovative treatment that will soon become available., Results: Of 143 answers received, 137 could be analysed, representing about 3.5% of patients with severe or moderate haemophilia over 16year-old. They were 80.3% with haemophilia A and 19.7 % with haemophilia B, with a severe form of the disease for 80.3 % of them. Curiosity for HGT was formulated by 64.2% of the participants, 33.6 % being interested by this approach as soon as it will be available and 38.7 % preferring to wait until more patients have been treated. Only 3.6 % of the participants would never consider receiving HGT. The level of awareness and knowledge was estimated to be limited by 39.5 % of the patients. More than 60 % of them declared having never or almost never discussed HGT with the team of their haemophilia centre. Before deciding to get HGT, 54.4 % of the participants considered that it will be very important to compare it with their current treatment and 53.7 % would like to be better informed by their care providers., Conclusions: These results highlight the need for training and education for patients, but also for professionals at haemophilia centres, about HGT and the shared decision-making process. Objective, unbiased and transparent information must be available for patients about this very promising therapy which nonetheless carries more uncertainty and unknowns compared to other haemophilia treatments., (© 2023 The Authors. Haemophilia published by John Wiley & Sons Ltd.)

Introduction: With recent approval of the first two gene therapies for haemophilia A and B, educational materials about AAV-based gene therapy are needed by the haemophilia community for a better understanding of this novel therapeutic approach and helping healthcare providers and patients making personalized choices amongst an increasing array of therapeutic options., Aim: To provide a comprehensive summary of the whole process of AAV-based gene therapy from basic principles to clinical implementation through an illustrated review., Methods: The authors, with expertise in and knowledge about gene therapy for haemophilia A and B, reviewed relevant articles from PubMed database and translated them into illustrations., Results: The review is divided into eight illustrated sections providing an overview of gene therapy for haemophilia A and B from haemophilia basics and current treatment landscape, principles of the AAV-based liver-directed gene therapy, through exploring the efficacy and safety results of published phase III clinical trials, current and future challenges, to implementation in clinical practice, including the hub and spoke models and the patient journey., Conclusion: This illustrated review educates healthcare professionals on AAV-based gene therapy for haemophilia A and B enabling them to further educate their peers and their patients., (© 2023 The Authors. Haemophilia published by John Wiley & Sons Ltd.)

Hemophilia A(HA) is an X-linked recessive bleeding disorder caused by mutations in coagulation factor VIII. Nowadays, exogenous coagulation factor replacement therapy is the main treatment. With the continuous development of gene therapy, new research directions have been provided for the treatment of hemophilia A. CRISPR-Cas9 technology was applied to select suitable target sites, and mediate the targeted knock-in and efficient expression of exogenous B-domain-deleted FⅧ variant gene through corresponding vectors for the treatment of hemophilia A.CRISPR-Cas9 technology is an emerging gene editing tool with great efficiency, safety and effectiveness, and has been widely used in hemophilia gene therapy research. This paper reviews the vector selection, construction of therapeutic genes, gene editing technology and selection of expression target sites for hemophilia A gene therapy at this stage.

Remarkably, it has been 40 years since the isolation of the 2 genes involved in hemophilia A (HA) and hemophilia B (HB), encoding clotting factor (F) VIII (FVIII) and FIX, respectively. Over the years, these advances led to the development of purified recombinant protein factors that are free of contaminating viruses from human pooled plasma for hemophilia treatments, reducing the morbidity and mortality previously associated with human plasma-derived clotting factors. These discoveries also paved the way for modified factors that have increased plasma half-lives. Importantly, more recent advances have led to the development and Food and Drug Administration approval of a hepatocyte-targeted, adeno-associated viral vector-mediated gene transfer approach for HA and HB. However, major concerns regarding the durability and safety of HA gene therapy remain to be resolved. Compared with FIX, FVIII is a much larger protein that is prone to misfolding and aggregation in the endoplasmic reticulum and is poorly secreted by the mammalian cells. Due to the constraint of the packaging capacity of adeno-associated viral vector, B-domain deleted FVIII rather than the full-length protein is used for HA gene therapy. Like full-length FVIII, B-domain deleted FVIII misfolds and is inefficiently secreted. Its expression in hepatocytes activates the cellular unfolded protein response, which is deleterious for hepatocyte function and survival and has the potential to drive hepatocellular carcinoma. This review is focused on our current understanding of factors limiting FVIII secretion and the potential pathophysiological consequences upon expression in hepatocytes., Competing Interests: Declaration of competing interests R.J.K. is a consultant for Miltenil Biotech. R.W.H. is serving on the scientific advisory boards and committees of Regeneron Pharmaceuticals, Pfizer, BioMarin, Spark Therapeutics, and Prevail Therapeutics and has received grant support from Hoffman-La Roche. Z.C. has no conflict of interest to disclose., (Copyright © 2023 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)

Gene therapy for hemophilia has been investigated for decades but no breakthroughs were made until Nathwani et al. achieved a significant and sustainable factor IX increase in hemophilia B patients in 2011. About eleven years later, in August 2022, the first hemophilia A gene therapy product was approved by the European Commission and hemophilia treatment entered a new era. This review does not focus on the newest advances but rather the practical aspects of gene therapy aiming to provide an overview for physicians who treat hemophiliacs who did not participate in the clinical trials. The current status of gene therapy, focusing particularly on products likely to be clinically available soon, are reviewed and summarized. Currently, possible limitations of gene therapy are pre-existing neutralizing antibodies toward the vector, liver health, age, and inhibitor status. Possible safety concerns include infusion reactions, liver damage, and adverse effects from immune suppressants or steroids. In summary, generally speaking, gene therapy is effective, at least for several years, but the exact effect may be unpredictable and intensive monitoring for several months is needed. It can also be considered safe with careful practice on selected patients. In its current form, gene therapy will not replace all hemophilia treatments. Advances in non-factor therapy will also improve hemophilia care greatly in the future. We envisage that gene therapy may be included in multiple novel therapies for hemophilia and benefit some hemophilia patients while novel non-factor therapies may benefit others, together fulfilling the unmet needs of all hemophilia patients., Competing Interests: Declaration of competing interest All authors have no relevant competing interest to declare., (Copyright © 2023. Published by Elsevier B.V.)

The introduction of adeno-associated virus-mediated, liver-directed gene therapy into the hemophilia treatment landscape brings not only great promise but also considerable uncertainty to a community that has a history punctuated by the devastating effects of HIV and hepatitis C virus. These infections were introduced into people with hemophilia through the innovation of factor concentrates in the 1970s and 1980s. Concentrates, heralded as a major advance in treatment at the time, brought devastation and death to the community already challenged by the complications of bleeding into joints, vital organs, and the brain. Over the past 5 decades, considerable advances in hemophilia treatment have improved the survival, quality of life, and participation of people with hemophilia, although challenges remain and health equity with their unaffected peers has not yet been achieved. The decision to take a gene therapy product is one in which an informed, holistic, and shared decision-making approach must be employed. Bias on the part of health care professionals and people with hemophilia must be addressed and minimized. Here, we review data leading to the regulatory authorization of valoctocogene roxaparvovec, an adeno-associated virus 5 gene therapy, in Europe to treat hemophilia A and etranacogene dezaparvovec-drlb in the United States and Europe to treat hemophilia B. We also provide an overview of the decision-making process and recommend steps that should be taken by the hemophilia community to ensure the safety of and optimal outcomes for people with hemophilia who choose to receive a gene therapy product., Competing Interests: Declaration of competing interests R.K. received research funding from Bayer. G.F.P. is a consultant for ASC Therapeutics, BioMarin, Frontera, Metagenomi, Pfizer, Regeneron, and Spark Therapeutics. M.W.S.’s institution has received research funding from BioMarin, Freeline, Spark Therapeutics, and uniQure. The other authors have no competing interests to disclose., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Extensive preclinical research over the past 30 years has culminated in the recent regulatory approval of several gene therapy products for hemophilia. Based on the efficacy and safety data in a recently conducted phase III clinical trial, Roctavian ® ( valoctocogene roxaparvovec ), an adeno-associated viral (AAV5) vector expressing a B domain deleted factor VIII (FVIII) complementary DNA, was approved by the European Commission and Food and Drug Administration (FDA) for the treatment of patients with severe hemophilia A. In addition, Hemgenix ® ( etranacogene dezaparvovec ) was also recently approved by the European Medicines Agency and the FDA for the treatment of patients with severe hemophilia B. This product is based on an AAV5 vector expressing a hyper-active factor IX (FIX) transgene (FIX-Padua) transgene. All AAV-based phase III clinical trials to date show a significant increase in FVIII or FIX levels in the majority of treated patients, consistent with a substantial decrease in bleeding episodes and a concomitant reduction in factor usage obviating the need for factor prophylaxis in most patients. However, significant interpatient variability remains that is not fully understood. Moreover, most patients encountered short-term asymptomatic liver inflammation that was treated by immune suppression with corticosteroids or other immune suppressants. In all phase III trials to date, FIX expression has appeared relatively more stable than FVIII, though individual patients also had prolonged FVIII expression. Whether lifelong expression of clotting factors can be realized after gene therapy requires longer follow-up studies. Further preclinical development of next-generation gene editing technologies offers new prospects for the development of a sustained cure for hemophilia, not only in adults, but ultimately in children with hemophilia too.

Introduction: Haemophilia B is a debilitating hereditary coagulation disorder characterized by prolonged or spontaneous episodes of bleeding caused by a deficiency of endogenous factor IX. In Algeria, even though many studies are being carried out to evaluate the prevalence and management of haemophilia B, there is a paucity of locally published literature that can be used to understand the most recent information on the disease's epidemiology, diagnostic techniques and treatment options., Aims: The aim of this manuscript is to raise awareness among patients and family clinicians about current practices, recent developments and unmet needs related to haemophilia B in Algeria., Methods: A comprehensive literature search was conducted through online scientific databases to review publications regarding haemophilia B in Algeria. Exclusions of the review include case studies, interregional comparisons, abstract-only papers and studies outside the range of 2012-2022., Results: The findings discussed relate to the epidemiology of haemophilia B in Algeria, the clinical diagnostic process, disease symptoms, the benefits of molecular and genetic testing, advancements in prophylactic care, as well as unmet needs hindering the progression of optimal haemophilia B management., Conclusion: These findings are crucial to encourage the maintenance of national registries with updated epidemiological data, facilitate early and timely detection of disease symptoms, improve the provision of diagnostic facilities and enhance the overall treatment landscape for better patient outcomes., (© 2023 John Wiley & Sons Ltd.)

Safe and efficient delivery of messenger RNAs for protein replacement therapies offers great promise but remains challenging. In this report, we demonstrate systemic, in vivo, nonviral mRNA delivery through lipid nanoparticles (LNPs) to treat a Factor IX (FIX)-deficient mouse model of hemophilia B. Delivery of human FIX (hFIX)mRNA encapsulated in our LUNAR LNPs results in a rapid pulse of FIX protein (within 4-6 h) that remains stable for up to 4-6 d and is therapeutically effective, like the recombinant human factor IX protein (rhFIX) that is the current standard of care. Extensive cytokine and liver enzyme profiling showed that repeated administration of the mRNA-LUNAR complex does not cause any adverse innate or adaptive immune responses in immune-competent, hemophilic mice. The levels of hFIX protein that were produced also remained consistent during repeated administrations. These results suggest that delivery of long mRNAs is a viable therapeutic alternative for many clotting disorders and for other hepatic diseases where recombinant proteins may be unaffordable or unsuitable. [ABSTRACT FROM AUTHOR]

Introduction: Congenital hemophilia B (HB) is an X-linked bleeding disorder resulting in Factor IX (FIX) deficiency and bleeding of variable severity. There is no cure for HB. Typical management consists of prophylactic intravenous (IV) recombinant or plasma-derived FIX infusions. Etranacogene dezaparvovec-drlb (Hemgenix, AMT-061) is an adeno-associated virus serotype 5 (AAV5) vector containing a codon-optimized Padua variant of the human F9 gene with a liver-specific promoter. Etranacogene dezaparvovec-drlb received FDA approval on 22 November 2022 for the treatment of HB in adult patients who use FIX prophylaxis therapy, have current or historical life-threatening hemorrhage, or have experienced repeated, serious spontaneous bleeding episodes., Areas Covered: This drug profile discusses the safety and efficacy of etranacogene dezaparvovec-drlb in patients with HB., Expert Opinion: Etranacogene dezaparvovec-drlb therapy results in stable and sustained expression of near-normal to normal FIX levels in patients with HB regardless of neutralizing antibodies to AAV5 up to a titer of 678. Its use has led to significant reduction in bleeding and FIX prophylaxis. Etranacogene dezaparvovec-drlb was well tolerated; however, 17% of patients required corticosteroid therapy for alanine aminotransferase (ALT) elevation. Etranacogene dezaparvovec-drlb therapy marks the beginning of an exciting era in HB treatment and opens questions regarding treatment longevity and long-term safety.

In contrast to the standard enzyme-replacement therapy, administered from once per 7-14 days to 2-3 times a week in patients with severe hemophilia B, as a result of a single injection, gene therapy can restore F9 gene expression and maintain it for a prolonged time. In clinical research, the approach of delivering a functional copy of a gene using adeno-associated viral (AAV) vectors is widely used. The scientific community is actively researching possible modifications to improve delivery efficiency and expression. In preclinical studies, the possibility of genome editing using CRISPR/Cas9 technology for the treatment of hemophilia B is also being actively studied.