International consensus recommendations on the management of people with haemophilia B

Assessing health care resource use, outcomes, and costs among Medicaid beneficiaries receiving factor IX prophylaxis for hemophilia B

BACKGROUND

Hemophilia B is characterized by a deficiency of clotting factor IX (FIX), leading to excessive bleeding. Hemophilia B is commonly treated using replacement FIX therapy, which may be administered prophylactically or on-demand following a bleeding episode. Previous research has found high health care resource use (HCRU) and costs among Medicare and commercially insured people with hemophilia B (PwHB), with FIX therapy being a primary driver of health care costs.

OBJECTIVE

To assess HCRU, outcomes, and costs among US Medicaid beneficiaries receiving FIX prophylaxis for hemophilia B.

METHODS

This study employed a retrospective comparative cohort design to assess HCRU, outcomes, and costs among adult male Medicaid beneficiaries receiving FIX prophylaxis for hemophilia B, relative to a matched comparator population of beneficiaries without bleeding disorders. Nationwide Medicaid claims and enrollment data from 2015 to 2020 were used for this analysis. Adult male PwHB who received FIX prophylaxis, defined as not having identified gaps in FIX therapy exceeding 60-days during a 1-year measurement period, and were continuously enrolled in Medicaid for at least 2 years, were matched 1:4 to comparator beneficiaries without bleeding disorders based on baseline demographic and clinical characteristics. Key measures of HCRU and outcomes included inpatient hospital admissions, outpatient hematologist visits, and bleeding events. Measures of health care costs were assessed among a subset of beneficiaries enrolled in fee-for-service Medicaid.

RESULTS

PwHB receiving FIX prophylaxis were significantly more likely to have multiple inpatient hospital admissions and had a longer cumulative length of stay per person relative to comparator beneficiaries (30.2 vs 14.8 days, respectively; P = 0.0473). PwHB receiving FIX prophylaxis also had significantly higher rates of bleeding events relative to comparator beneficiaries (0.54 vs 0.02 per person, respectively; P < 0.0001) and outpatient hematologist visits (1.58 vs 0.20 per person, respectively; P < 0.0001). Annual costs among PwHB receiving FIX prophylaxis were significantly higher than costs among comparator beneficiaries ($928,370 vs $34,553 per person, respectively; P < 0.0001) and were overwhelmingly driven by costs associated with FIX therapy.

CONCLUSIONS

This analysis found higher rates of HCRU and costs among Medicaid beneficiaries receiving FIX prophylaxis for hemophilia B relative to a matched comparator population of beneficiaries without bleeding disorders. Future research should examine hemophilia B costs and outcomes within the context of new treatments with innovative mechanisms of action, such as gene therapies, RNA interference therapies, and antitissue factor pathway inhibitor therapies.

Fitusiran prophylaxis in people with hemophilia A or B who switched from prior BPA/CFC prophylaxis: the ATLAS-PPX trial

ABSTRACT

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

Recombinant factor IX Fc for the treatment of hemophilia B

Current hemophilia B treatment guidelines recommend routine prophylaxis with factor IX (FIX) replacement products, tailored to maintain plasma activity at levels that will prevent bleeds. However, plasma FIX activity may not be the primary determinant or best indicator of hemostatic efficacy due to its extravascular distribution. FIX replacement therapy has evolved to include extended half-life (EHL) products that provide effective bleed protection when administered at intervals of 7 days or longer. rFIXFc is a recombinant fusion protein with an extended circulation time. rFIXFc has a biodistribution profile consistent with distribution into extravascular space, where it may support hemostasis at sites of vessel injury independent of circulating plasma activity levels. The safety and efficacy of rFIXFc prophylaxis is well established in adults, adolescents and children including previously untreated patients with hemophilia B, with substantial evidence from clinical trials and real-world clinical practice. This review describes the pharmacokinetic characteristics of rFIXFc, summarizes available safety and efficacy data, and evaluates the use of rFIXFc in special populations. Current hemophilia B treatment challenges, including target FIX plasma levels, perioperative use, and management of patients with comorbidities, are discussed together with the potential role of EHL products in the future treatment landscape of hemophilia B.

Haemophilia in the era of novel therapies: Where do inhibitors feature in the new landscape?

INTRODUCTION

The advent of therapeutic recombinant factor VIII (FVIII) and factor IX (FIX) protein infusions revolutionized the care of persons with haemophilia in the 1990s. It kicked off an era with the increasing use of prophylactic factor infusions for patients and transformed conversations around the ideal trough activity levels as well as the ultimate goals in tailored, individualized care. Our knowledge surrounding the immunologic basis of inhibitor development and treatment derives from a time when patients were receiving frequent factor infusions and focused on immune tolerance induction following inhibitor development.

DISCUSSION

More recently, care was revolutionized again in haemophilia A with the approval of emicizumab, a bispecific antibody mimicking activated FVIII function, to prevent bleeding. The use of emicizumab prophylaxis has resulted in a significantly slower accumulation of factor exposure days and continued effective prophylaxis in the case of inhibitor development. While emicizumab is effective at reducing the frequency of bleeding events in patients with haemophilia A, management of breakthrough bleeds, trauma, and surgeries still requires additional treatment. Ensuring that FVIII is a therapeutic option, particularly for life-threatening bleeding events and major surgeries is critical to optimizing the care of persons with haemophilia A. Other novel non-factor concentrate therapies, including rebalancing agents, will dramatically change the landscape for persons with haemophilia B with inhibitors.

CONCLUSION

This review discusses the changing landscape regarding the timing of inhibitor development and management strategies after inhibitor development, stressing the importance of education across the community to continue to vigilantly monitor for inhibitors and be prepared to treat persons with inhibitors.

The current challenges faced by people with hemophilia B

Hemophilia B (HB) is a rare, hereditary disease caused by a defect in the gene encoding factor IX (FIX) and leads to varying degrees of coagulation deficiency. The prevailing treatment for people with HB (PWHB) is FIX replacement product. The advent of recombinant coagulation products ushered in a new era of safety, efficacy, and improved availability compared with plasma-derived products. For people with severe HB, lifelong prophylaxis with a FIX replacement product is standard of care. Development of extended half-life FIX replacement products has allowed for advancements in the care of these PWHB. Nonetheless, lifelong need for periodic dosing and complex surveillance protocols pose substantive challenges in terms of access, adherence, and healthcare resource utilization. Further, some PWHB on prophylactic regimens continue to experience breakthrough bleeds and joint damage, and subpopulations of PWHB, including women, those with mild-to-moderate HB, and those with inhibitors to FIX, experience additional unique difficulties. This review summarizes the current challenges faced by PWHB, including the unique subpopulations; identifying the need for improved awareness, personalized care strategies, and new therapeutic options for severe HB, which may provide future solutions for some of the remaining unmet needs of PWHB.

Patient perspective on living with mild hemophilia in Germany: results from a nationwide survey

Introduction

The disease burden and bleeding risk of patients with mild hemophilia may be underestimated. Their health-related quality of life (QoL) may be negatively impacted by insufficient treatment and bleed-related joint damage connected to a potentially delayed diagnosis.

Aim

This study aims to gain information on the care reality and QoL of patients aged ≥12 years with mild hemophilia in Germany.

Methods

An anonymous cross-sectional patient survey using standardized questionnaires was conducted in a validated electronic patient-reported outcome system. Medical specialists, hemophilia centers, patient organizations, and support groups across Germany invited the patients.

Results

A total of 43 patients (35 patients with hemophilia A, 5 patients with hemophilia B, and 3 patients for whom the information was missing) with a median age of 33 years were analyzed. The median age at diagnosis was 6.0 years (interquartile range [IQR] 2.0-15.0), and the median factor activity was 14.0% (IQR 12.0-25.0). Nearly 85% of the patients received factor concentrates in the past, and the most common reasons for the treatment were surgery or joint bleeding (each 65.6%). Half of the patients who provided feedback experienced complications during bleeding episodes. Prophylactic treatment with factor concentrates was rare (10.3%). The patients had minor problems regarding their health status.

Conclusion

Bleeding complications and joint bleeding, in particular, may be highly underestimated in patients with mild hemophilia, highlighting a medical need in this population. Patients with a potential benefit from prophylaxis need to be identified. Mild hemophilia has a negative impact on patients' QoL. Hemophilia centers satisfied the patients' needs. Further research is needed to address the current lack of awareness and improve adequate treatment in the future.

A new population pharmacokinetic model for recombinant factor IX-Fc fusion concentrate including young children with haemophilia B

AIMS

Recombinant factor IX Fc fusion protein (rFIX-Fc) is an extended half-life factor concentrate administered to haemophilia B patients. So far, a population pharmacokinetic (PK) model has only been published for patients aged ≥12 years. The aim was to externally evaluate the predictive performance of the published rFIX-Fc population PK model for patients of all ages and develop a model that describes rFIX-Fc PK using real-world data.

METHODS

We collected prospective and retrospective data from patients with haemophilia B treated with rFIX-Fc and included in the OPTI-CLOT TARGET study (NTR7523) or United Kindom (UK)-EHL Outcomes Registry (NCT02938156). Predictive performance was assessed by comparing predicted with observed FIX activity levels. A new population PK model was constructed using nonlinear mixed-effects modelling.

RESULTS

Real-world data were obtained from 37 patients (median age: 16 years, range 2-71) of whom 14 were aged <12 years. Observed FIX activity levels were significantly higher than levels predicted using the published model, with a median prediction error of -48.8%. The new model showed a lower median prediction error (3.4%) and better described rFIX-Fc PK, especially for children aged <12 years. In the new model, an increase in age was correlated with a decrease in clearance (P < .01).

CONCLUSIONS

The published population PK model significantly underpredicted FIX activity levels. The new model better describes rFIX-Fc PK, especially for children aged <12 years. This study underlines the necessity to strive for representative population PK models, thereby avoiding extrapolation outside the studied population.

The road to implementation of pharmacokinetic-guided dosing of factor replacement therapy in hemophilia and allied bleeding disorders. Identifying knowledge gaps by mapping barriers and facilitators

Clinical guidelines and expert groups recommend the use of pharmacokinetic (PK)-guided dosing of factor replacement therapy for the treatment of bleeding disorders, especially for patients with hemophilia. Although PK-guided dosing is increasingly applied, it is generally not considered standard clinical practice. The aim of this scoping review is to map barriers and facilitators for the implementation of PK-guided dosing in clinical practice and to identify knowledge gaps. A literature search was performed and 110 articles were included that describe PK-guided dosing in patients with bleeding disorders, mostly hemophilia A. We defined two overarching themes, efficacy and feasibility, and discuss five topics within each theme. For each topic, barriers, facilitators and knowledge gaps were described. Although consensus was found with regard to some topics, contradicting reports were found for others, especially with respect to the efficacy of PK-guided dosing. These contradictions highlight the need for future research to elucidate current ambiguities.

Efficacy of rFIXFc versus N9-GP Prophylaxis in Patients with Hemophilia B: Matching-Adjusted Indirect Comparison of B-LONG and PARADIGM 2 Trials

Purpose

For patients with hemophilia B, extended half-life factor IX (FIX) products are available for prophylaxis and for treating bleeds. Different methods are used to extend the half-lives of recombinant FIX Fc fusion protein (rFIXFc) and nonacog beta pegol (N9-GP). This affects their biodistribution and plasma FIX levels, although differences do not always correlate with clinical outcomes. A matching-adjusted indirect comparison (MAIC) of prophylaxis with rFIXFc and N9-GP was performed, based on licensed dosing in the European Union.

Patients and Methods

Combined rFIXFc data from the weekly and individualized interval prophylaxis arms of the B-LONG clinical trial, and N9-GP data from the 40 IU/kg once-weekly prophylaxis arm of PARADIGM 2 were used in a MAIC. Individual patient data for rFIXFc (n=87) were matched to aggregated data for N9-GP (n=29). Estimated annualized bleeding rates (ABRs) for rFIXFc were recalculated using a Poisson regression model with adjustment for over-dispersion, and compared with ABRs reported for N9-GP, using incidence rate ratios (IRRs) with 95% confidence interval (CI).

Results

There was no evidence of significant differences in estimated ABRs between prophylaxis with rFIXFc and N9-GP. Analysis of pooled rFIXFc weekly and interval-adjusted dosing compared with N9-GP 40 IU/kg once weekly produced estimated ABRs of 2.59 versus 2.51 (IRR 1.03; 95% CI 0.56-1.89), as well as 1.34 versus 1.22 (IRR 1.10; 95% CI 0.42-2.91) and 1.13 versus 1.29 (IRR 0.88; 95% CI 0.47-1.63) for overall, spontaneous, and traumatic bleeding events, respectively.

Conclusion

The study did not reveal any significant differences in the efficacy of rFIXFc and N9-GP prophylaxis. Given differences in trough levels (rFIXFc dosing was targeted to achieve a trough 1-3 IU/dL above baseline versus a reported estimated N9-GP mean trough of 27.3 IU/dL), interpreting plasma FIX levels as potential surrogate efficacy markers requires consideration of compound-specific pharmacokinetic profiles.

Etranacogene dezaparvovec for the treatment of adult patients with severe and moderately severe hemophilia B

INTRODUCTION

Etranacogene dezaparvovec is the first gene therapy approved for treatment of adults with severe and moderately severe hemophilia B.

AREAS COVERED

This review describes the results of the clinical trial program of AMT-060 and etranacogene dezaparvovec, outlining the pharmacokinetic, clinical efficacy and safety data. With the entry of etranacogene dezaparvovec into the market, this review summarizes the treatment landscape in hemophilia B and discusses the current unknowns in the field.

EXPERT OPINION

Gene therapy appears to be a feasible option for adults with severe and moderately severe hemophilia B. Etranacogene dezaparvovec enables most patients to reach stable factor IX (FIX) levels after a single intravenous infusion, eliminating the need for regular prophylaxis; thus, drastically reducing treatment burden and avoiding variable bleeding risk owing to fluctuating FIX activity levels. Efficacy of etranacogene dezaparvovec has been demonstrated even in the presence of preexisting neutralizing antibodies (up to a titer of 1:678), with a relative low risk of transaminitis and its associated potential loss of transgene expression. However, long-term data are required to ascertain the durability of FIX levels achieved and safety. The cost-effectiveness and adoption of innovative payment models for reimbursement are key in choosing gene therapy over existing treatments.

Clinicopathological Parameters of Haemophilia Patients at a Tertiary Care Centre in Northern India

INTRODUCTION

Haemophilia affects a large number of people all over the world, yet very little is known about the clinical manifestations and diagnostic protocols of the condition in areas with limited access to resources in developing countries. Understanding the clinical spectrum and diagnostic approach will help with the design of measures to address the situation in these places. The primary objective of this study was to examine the clinicopathological parameters of haemophiliac patients.

MATERIALS AND METHODS

From the departmental archive, a thorough history of each patient was retrieved, including values of bleeding time, prothrombin time, activated partial prothrombin time, and percentage of specific factor activity.

RESULTS

Out of a total of 385 cases over the period of six years, 86.75% were classified as haemophilia A and 13.25% of cases were diagnosed as haemophilia B. In terms of the severity of the disease, 44.93% were classified as severe, 42.08% as moderate, and 12.99% as mild. Joint bleeding was the first and most typical clinical manifestation of the disease, accounting for 34.80% of cases, followed by ecchymosis (23.12%), post-traumatic bleeding (12.73%), epistaxis (12.20%), and gum bleeding (8.05%). 1.56% of patients had a positive screening test for the hepatitis C virus, followed by 1.30% for HIV and 0.78% for hepatitis B surface antigen.

CONCLUSION

In the presence of joint bleeding, ecchymosis, and post-traumatic bleeding in an otherwise healthy individual, a clinician should be alerted to the possibility that the patient has haemophilia and should request a work-up for the bleeding disorder.

Concizumab: First Approval

Concizumab (Alhemo™), a subcutaneously administered humanised monoclonal IgG4 antibody against tissue factor pathway inhibitor (TFPI), binds to the Kunitz-2 domain of TFPI and prevents TFPI from binding to activated Factor X. Concizumab is being developed by Novo Nordisk for the treatment of hemophilia A and B with and without inhibitors. In March 2023, concizumab was approved in Canada for the treatment of adolescent and adult patients (12 years of age or older) with hemophilia B who have FIX inhibitors and require routine prophylaxis to prevent or reduce the frequency of bleeding episodes. This article summarizes the milestones in the development of concizumab leading to this first approval for the treatment of hemophilia B.

Eftrenonacog Alfa: A Review in Haemophilia B

Eftrenonacog alfa (Alprolix^®) is an extended half-life recombinant factor IX (rFIX)-Fc fusion protein (hereafter referred to as rFIXFc). Administered as an intravenous bolus, it is approved for prophylactic use and the treatment of bleeding in patients with haemophilia B in various countries worldwide, including those of the EU, as well as the USA. In multinational, phase III trials, rFIXFc was effective for the prophylaxis, perioperative management or on-demand treatment of bleeding in male patients with severe haemophilia B regardless of age and irrespective of whether or not they had been previously treated with FIX replacement products. Prophylactic efficacy was maintained over the longer term (up to 5 years) in previously treated patients. rFIXFc effectiveness in the real-world setting is supported by results of prospective studies, as well as the outcomes of several retrospective trials. rFIXFc was well tolerated in clinical trials in previously treated and untreated children, adolescents and/or adults with severe haemophilia B. Thus, rFIXFc continues to represent a useful treatment option among the haemophilia B patient population.

Current factor IX replacement options for hemophilia B and the challenges ahead

INTRODUCTION

Therapy for hemophilia B is aimed at replacing the congenital deficiency of coagulation factor IX (FIX). For replacement therapy, several FIX concentrates derived from donated human plasma or engineered by recombinant DNA technology are currently commercially available. The use of these products is well established and permit patients a relatively normal life. To further improve treatment efficacy, recombinant FIX products with a prolonged half-life have been developed, allowing relaxed prophylactic dosing and reducing treatment burden.

AREAS COVERED

In this review, we explore the current FIX replacement options for hemophilia B patients by analyzing the outcomes of their main clinical trials. We cover advances in the FIX molecules with extended half-life (EHL). Published literature on products for replacement of hemophilia B was retrieved using PubMed with no temporal limits.

EXPERT OPINION

The recent introduction of recombinant EHL FIX products has represented a major advance in the therapeutic management of hemophilia B patients, permitting both a reduction of treatment burden and improving patients' compliance to prophylaxis and, ultimately, quality of life.

Osteoporosis in hemophilia: what is its importance in clinical practice?

INTRODUCTION

The relationship between severe hemophilia and osteoporosis has been well established in the literature. However, although the importance of its prevention in order to reduce the risk of bone fractures has been reported, the importance of its treatment in clinical practice has not been well analyzed.

AREAS COVERED

In this paper a review of the available clinical and experimental information on osteoporosis in hemophilia has been performed, to better understand the relationship between hemophilia and osteoporosis. Prevention of osteoporosis in hemophilia should include primary hematological prophylaxis; a diet appropriate in calcium and vitamin D; a regular exercise program that includes aerobics, strength training and balance and flexibility activities; restriction of tobacco and alcohol use; and limitation of the duration of immobilization.

EXPERT OPINION

Prevention of osteoporosis in hemophilic patients is paramount. However, it is noteworthy that there is only one publication on the treatment of osteoporosis in patients with hemophilia. Until further research is done on this topic, the existing recommendations for non-hemophilic patients should be followed. They include the use of antiresorptives (estrogens, selective estrogen receptor modulators, bisphosphonates, denosumab) and anabolic agents (teriparatide, abaloparatide, romosozumab). Further studies on the management of osteoporosis in patients with hemophilia are required.