A systematic review of cost-effectiveness analyses of gene therapy for hemophilia type A and B.

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.

The genetic analysis of eight families with hemophilia B in Mongolia: Identification of two novel mutation.

BACKGROUND: This study aimed to conduct molecular diagnostics among individuals with hemophilia B (HB) and carriers of hemophilia in Mongolia. METHODS: Eight patients (six severe, two mild) with HB and their 12 female relatives were enrolled from eight families. Sanger sequence was performed for mutation identification. The questionnaire survey was conducted to evaluate carrier symptoms in female relatives. RESULTS: Two families had a history of HB. A total of five different variants (c.223C > T; c.344A > G; c.464G > C; c.187_188del; and c.1314_1314delA) were identified in six patients with severe HB. Of these, two (c.187_188del and c.1314_1314delA) were novel. No variant in the entire F9 was found in two patients with mild HB. Nonsense c.223C > T (p.Arg75*) mutation was detected in two unrelated patients. Carrier testing identified five mothers as carriers, while one younger sister was a non-carrier. The carrier status of six female relatives of the two mild patients remained undetermined. By questionnaire survey, only one of the five genetically identified carriers displayed noticeable symptoms of being a carrier. CONCLUSION: The novel variants c.187_188del and c.1314_1314delA can cause severe hemophilia B. This study did not observe a significant association between symptoms and carrier status in the five carriers.

Gene Therapy with Fidanacogene Elaparvovec in Adults with Hemophilia B.

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 5×1011 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.).

Pharmacokinetic model-based assessment of factor IX prophylaxis treatment regimens in severe hemophilia B.

An important aspect of improving care for people with hemophilia B (HB) is developing optimal treatment strategies. Here we aimed to provide in-silico evidence, comparing the estimated optimal posology of factor IX (FIX) products to support the patient-physician decision-making process. A population pharmacokinetic (popPK) model-based assessment comparing the performance of FIX products (rFIX, rIX-FP, rFIXFc, N9-GP) was developed. PopPK analyses were used to determine a product's optimal posology to target predefined steady-state FIX activity trough levels in a hypothetical population of 10,000 people with severe HB. Model-derived optimal posologies were compared across several parameters including trough levels, proportion of patients per regimen and consumption, considering 64 hypothetical patient scenarios of different FIX trough level targets and ages. Results indicated a marked difference between FIX products estimated to achieve target trough levels, consumption and dosing frequencies. rIX-FP was associated with higher trough levels than rFIX and rFIXFc, at a lower weekly dose and administration frequency, across all age groups. N9-GP use in adolescents and adults was associated with lower consumption compared with rIX-FP. Insights from this study may be utilized by clinicians to inform decision-making, by considering the model-generated estimated optimal posologies alongside multiple clinical factors and patient preferences.

Study on the Mutation of Fâ ¨ Gene in 31 Patients with Type B Hemophilia.

Hemophilia B (HB) is an inherited bleeding disorder caused by defects in the FⅨ gene, leading to severe coagulation dysfunction. This study designed eight pairs of primers covering eight exons of the FⅨ gene and used PCR and DNA sequencing to detect FⅨ gene mutations in 31 HB patients. Sequencing results were compared with normal sequences using Chromas software on Blast to identify mutation sites. Findings revealed the CpG dinucleotide region as a mutation hotspot and the 192nd nucleotide (FⅨ192) as a dinucleotide polymorphism site in the Chinese population. Pathogenic mutations included point mutations, deletions, insertions, and mutations affecting amino acids or splicing sites. For cases with only polymorphic sites, further exon sequencing is needed. This study adds new mutation data to the global HB database, supports research on racial differences in FⅨ gene mutations, and contributes to domestic HB statistics. The results aid in understanding the FⅨ gene's role in coagulation, elucidating HB pathogenesis, and providing a basis for future gene therapy.

Transplacental delivery of factor IX Fc-fusion protein ameliorates bleeding phenotype of newborn hemophilia B mice.

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.

Factor IX stimulants in preclinical and early phase trials for hemophilia B treatment.

INTRODUCTION: Hemophilia B is a X-linked rare inherited bleeding disorder characterized by coagulation factor IX (FIX) deficiency. Therapy for hemophilia B is aimed at replacing the FIX deficiency by means of several plasma-derived or recombinant FIX products. The recent availability of recombinant FIX concentrates with a prolonged FIX half-life represented a great technological advance, permitting more spaced drug infusions and reducing treatment burden among hemophilia B patients. AREAS COVERED: This review summarizes the main preclinical and phase 1/2 studies investigating the innovative hemostatic products for hemophilia B replacement therapy. EXPERT OPINION: The significant recent technological advantages in the treatment of hemophilia B has led to the development of innovative FIX products aimed at further extending FIX half-life and using increasingly effective and convenient modes of administration. These novel hemostatic agents, currently in the preclinical or early clinical phase of development, carry the potential of improving patients' health status and quality of life. Continuous research is anyway needed to offer such patients a concrete chance of conducting a normal existence, like to non-affected age-matched individuals.

The impact of capping health system cost savings on the projected cost-effectiveness of etranacogene dezaparvovec compared with factor IX prophylaxis for the treatment of hemophilia B.

This viewpoint discusses cost-effectiveness estimates for EtranaDez, a gene therapy for hemophilia B, using the Institute for Clinical and Economic Review's (ICER) framework for single and short-term therapies (SSTs). EtranaDez offers long-term benefits from a single administration, in contrast to the high costs and frequent dosing required by current factor IX prophylaxis. However, the projected gains in health from EtranaDez are small relative to the cost implications of the therapy, and consequently, how the cost offsets associated with EtranaDez are counted has a substantial impact on assessing its cost-effectiveness. Strategies for assessing cost offsets used in the ICER SST framework include a 50/50 cost-sharing model between the health care system and the manufacturer and a cap of $150,000 annually on health care cost offsets. Results from the standard full cost-offset analysis as reported by ICER depicted EtranaDez as a dominant therapy with substantial cost savings compared with factor IX prophylaxis. However, while considering the ICER SST framework, particularly the $150,000 annual cap scenario, the cost-effectiveness was significantly reduced. The incremental cost-effectiveness ratio varied notably between these scenarios, challenging the conventional perception of value of gene therapy in health care. These cost-sharing scenarios highlight the potential of the ICER SST framework to help curtail inefficient health care spending. In cases in which the cost of existing treatment is exceedingly high, the application of such frameworks would improve efficiency in resource allocation, fostering a balance between incentives for innovation and economic sustainability in managed care systems.

Investigation and Analysis of the Current Status of Health-Related Quality of Life in Adolescents with Hemophilia in Hubei Province.

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.

Enhanced procoagulant activity of select hemophilia B causing factor IX variants with emicizumab.

ABSTRACT: Emicizumab improves the procoagulant activity of select loss-of-function factor IX (FIX) variants with likely dysfunctional assembly of the intrinsic Xase complex, resulting in hemophilia B (HB). FVIII mimetics may represent an alternative nonfactor therapy for select patients with HB.

Disease and treatment burden of patients with haemophilia entering the explorer6 non-interventional study.

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.

Characterization of recombinant factor IX fusion proteins enabling subcutaneous administration.

BACKGROUND: The X-linked bleeding disorder hemophilia B, caused by mutation(s) in the coagulation factor (F)IX gene, leads to partial or total loss of its function, requiring lifelong FIX replacement therapy. Although new recombinant FIX (rIX) therapeutics like albumin fusion proteins (rIX-FP) enable longer plasma half-life and thus less frequent administration, the complexity of intravenous (i.v.) injection remains. OBJECTIVES: The study aimed to characterize rIX-FP variants with anticipated enhanced specific activity, which would leverage rIX-FP's superior pharmacokinetic profile with beneficial characteristics for subcutaneous (s.c.) administration. METHODS: Two rIX-FP variants, R338L ("Padua variant") and R338L/E410K, were characterized in vitro. Pharmacokinetic profiles of FIX antigen and activity levels were evaluated in FIX-deficient mice after i.v. and s.c. administration of these variants (dosing based on antigen levels). The efficacy of the most promising variant was tested after i.v. and s.c. administration (dosing based on activity) in a tail clip bleeding model. A marketed wild-type (WT) rIX-FP product served as the comparator. RESULTS: Both rIX-FP variants showed a 4- to 5-fold increase in specific activity in vitro compared with rIX(WT)-FP, while FXIa-mediated activation was the fastest for rIX(WT)-FP and rIX(R338L)-FP. Compared with rIX(WT)-FP and rIX(R338L/E410K)-FP, rIX(R338L)-FP exhibited higher FIX activity exposure after i.v. and s.c. administration and demonstrated comparable efficacy with rIX(WT)-FP in reducing bleeding time and blood loss in FIX-deficient mice requiring ∼4 times lower protein amount. CONCLUSION: rIX(R338L)-FP was shown to be a promising candidate for s.c. administration, exhibiting increased specific activity combined with higher activity-based exposure and indicating efficacy at a lower protein dose.

An integrated multitool analysis contributes elements to interpreting unclassified factor IX missense variants associated with hemophilia B.

BACKGROUND: Dissection of genotype-phenotype relationships in hemophilia B (HB) is particularly relevant for challenging (mild HB) or for HB-associated but unclassified factor (F)IX missense variants. OBJECTIVE: To contribute elements to interpret unclassified HB-associated FIX missense variants by a multiple-level approach upon identification of a reported, but uncharacterized, FIX missense variant associated with mild HB. METHODS: Molecular modeling of wild-type and V92A FIX variants, expression studies in HEK293 cells with evaluation of protein (ELISA, western blotting) and activity (activated partial thromboplastin time-based/chromogenic assays) levels after recombinant expression, and multiple prediction tools. RESULTS: The F9(NM_000133.4):c.275T>C (p.V92A) variant was found in a mild HB patient (antigen, 45.4 U/dL; coagulant activity, 23.6 IU/dL; specific activity, 0.52). Newly generated molecular models showed alterations in Gla/EGF1-EGF2 domain conformation impacting Ca++ affinity and protein-protein interactions with activated factor XI (FXIa). Multitool analysis indicated a moderate impact on protein structure/function of the valine-to-alanine substitution, in accordance with patient and modeling data. Expression studies on the V92A variant showed a specific activity (0.49 ± 0.07; wild-type, 1.0 ± 0.1) recapitulating that of the natural variant, and pointed toward a moderate activation impairment as the main determinant underlying the p.V92A defect. The validated multitool approach, integrated with evidence-based data, was challenged on a panel (n = 9) of unclassified FIX missense variants, which resulted in inferred protein (secretion/function) outputs and HB severity. CONCLUSION: The rational integration of multitool and multiparameter analyses contributed elements to interpret genotype/phenotype relationships of unclassified FIX missense variants, with implications for diagnosis, management, and treatment of HB patients, and potentially translatable into other human disorders.

[Haemophilia B therapy: impact of the reimbursability of a long-acting recombinant factor on pharmaceutical expenditure in Italy]. / Terapia dell'emofilia B: impatto dell'ammissione alla rimborsabilità di un fattore ricombinante long-acting sulla spesa farmaceutica in Italia.

OBJECTIVES: to assess the variability in expenditure compared to 2022 assuming different rates of shifting of therapy days from current active ingredients used for the treatment of haemophilia B to nonacog beta pegolDesign: descriptive cross-sectional study. SETTING AND PARTICIPANTS: consumption in the year 2022 (data source: Medicines Utilisation Monitoring Centre, Italian Medicines Agency) of all medicinal products available in Italy containing coagulation factor IX. MAIN OUTCOMES MEASURES: for each active ingredient, the total number of therapy days and the variability in expenditure compared to 2022 were estimated on the basis of a switch of therapy days, between 5% and 20%, to nonacog beta pegol. RESULTS: on the basis of considered scenarios, the analysis shows that the total annual expenditure for clotting factors used in the treatment of haemophilia B could remain at most unchanged or reduced. Particularly, the extent of the reduction in spending could vary from 0.11% to 2.26%. This trend would be in contrast to the stable increase seen in recent years, particularly in 2022. CONCLUSIONS: this predictive spending assessment may be useful in evaluating the economic impact from new treatment options, such as etranacogene dezaparvovec gene therapy already approved by the European Medicines Agency and the Food and Drug Administration, and to improve pharmaceutical governance.

Recent Advances in Gene Therapy for Hemophilia: Projecting the Perspectives.

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.

Human umbilical cord mesenchymal stem cell-based gene therapy for hemophilia B using scAAV-DJ/8-LP1-hFIXco transduction.

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.

International Society on Thrombosis and Haemostasis clinical practice guideline for treatment of congenital hemophilia A and B based on the Grading of Recommendations Assessment, Development, and Evaluation methodology.

BACKGROUND: Hemophilia is a rare congenital bleeding disorder that results from complete or partial deficiency of blood coagulation factor (F)VIII (hemophilia A) or FIX (hemophilia B) due to pathogenic variants in their coding genes. Hemophilia requires complex management. To date, there is no evidence-based clinical practice guideline on hemophilia treatment based on the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. OBJECTIVES: This evidence-based clinical practice guideline from the International Society on Thrombosis and Haemostasis aims to provide an overview of evidence and support patients, caregivers, hematologists, pediatricians, other clinicians, researchers, and stakeholders in treatment decisions about congenital hemophilia A and B. METHODS: The International Society on Thrombosis and Haemostasis formed a multidisciplinary guideline panel of physicians and patients with global representation, balanced to minimize potential bias from conflicts of interest. The panel prioritized a set of clinical questions and outcomes according to their importance for clinicians and patients. A methodological team supported the guideline development process, including searching for evidence and performing systematic reviews. The GRADE approach was used, including GRADE Evidence to Decision frameworks. The recommendations were subject to public comment. RESULTS: The panel selected 13 questions, of which 11 addressed the treatment of hemophilia A and 2 the treatment of hemophilia B. Specifically, the panel addressed questions on prophylactic and episodic treatment with FVIII concentrates, bypassing agents, and nonfactor therapy (emicizumab) for hemophilia A (with and without inhibitors) as well as immune tolerance induction for hemophilia A. For hemophilia B, the panel addressed questions on prophylactic and episodic treatment of bleeding events with FIX concentrates. Agreement was reached for all 13 recommendations, of which 7 (54%) were based on evidence from randomized clinical trials, 3 (23%) on observational studies, and 3 (23%) on indirect comparisons. CONCLUSION: Strong recommendations were issued for prophylactic over episodic treatment for severe and moderately severe hemophilia A and B. Only conditional recommendations were issued for the remaining questions. Future research should focus on direct treatment comparisons and the treatment of hemophilia B with and without inhibitors. Future updates of this guideline will provide an updated evidence synthesis on the current questions and focus on new FVIII and FIX concentrates, novel nonfactor therapies, and gene therapy for severe and nonsevere hemophilia A and B.