Cost analysis of plasma-derived factor VIII/von Willebrand factor versus recombinant factor VIII for treatment of previously untreated patients with severe hemophilia A in the United States

Shifting Paradigms and Arising Concerns in Severe Hemophilia A Treatment

The management of hemophilia A has undergone a remarkable revolution, in line with technological advancement. In the recent past, the primary concern associated with Factor VIII (FVIII) concentrates was the risk of infections, which is now almost resolved by advanced blood screening and viral inactivation methods. Improving patients' compliance with prophylaxis has become a key focus, as it can lead to improved health outcomes and reduced health care costs in the long term. Recent bioengineering research is directed toward prolonging the recombinant FVIII (rFVIII) coagulant activity and synthesising higher FVIII yields. As an outcome, B-domain deleted, polyethylene glycolated, single-chain, Fc-fused rFVIII, and rFVIIIFc-von Willebrand Factor-XTEN are available for patients. Moreover, emicizumab, a bispecific antibody, is commercially available, whereas fitusiran and tissue factor pathway inhibitor are in clinical trial stages as alternative strategies for patients with inhibitors. With these advancements, noninfectious complications, such as inhibitor development, allergic reactions, and thrombosis, are emerging concerns requiring careful management. In addition, the recent approval of gene therapy is a major milestone toward a permanent cure for hemophilia A. The vast array of treatment options at our disposal today empowers patients and providers alike, to tailor therapeutic regimens to the unique needs of each individual. Despite significant progress in modern treatment options, these highly effective therapies are markedly more expensive than conventional replacement therapy, limiting their access for patients in developing countries.

Are We Capturing the Socioeconomic Burden of Rare Genetic Disease? A Scoping Review of Economic Evaluations and Cost-of-Illness Studies

BACKGROUND AND OBJECTIVES

Rare diseases have a significant impact on patients, families, the health system, and society. Measuring the socioeconomic burden is crucial to valuing interventions for rare diseases. Healthcare system costs are significant, but so are costs to other government sectors, patients, families, and society. To understand the breadth of costs captured in rare disease studies, we examined the cost categories and elements of socioeconomic burden captured in published studies.

METHODS

A scoping review was conducted using five electronic databases to identify English language economic evaluations and cost-of-illness studies of interventions for rare diseases (2011-21). We mapped costs using a previously developed evidence-informed framework of socioeconomic burden costs for rare disease.

RESULTS

Of 4890 studies identified, 48 economic evaluations and 22 cost-of-illness studies were included. While 18/22 cost-of-illness studies utilized a societal perspective, only 7/48 economic evaluations incorporated societal costs. Most reported cost categories related to medical costs, with medication and hospitalizations being the most common elements for both study designs. Costs borne by patients, families, and society were reported less among economic evaluations than cost-of-illness studies. These included: productivity (10% vs 77%), travel/accommodation (6% vs 68%), government benefits (4% vs 18%), and family impacts (0% vs 50%).

CONCLUSIONS

Contrary to cost-of-illness analyses, most of the included economic evaluations did not account for the hidden burden of rare diseases, that is, costs borne by patients, families, and societies. Including these types of costs in future studies would provide a more comprehensive picture of the burden of disease, providing empirical data to inform how we value and make decisions regarding rare disease interventions, health policy, and resource allocation.

Correlation Analysis of DNA Methylation in the von Willebrand Factor Promoter Region and the Risk of Unexplained Recurrent Hemophilia: Systematic Review and Meta-Analysis

This study systematically reviewed the effect of DNA methylation in the promoter region of the coagulation factor vWF gene on the risk of unexplained recurrent hemophilia. PubMed, Medline, Web of Science, and other computers were used to search the database, and the statistical randomized controlled trials of coagulation factor vWF in the risk analysis of unknown recurrent hemophilia were collected. The Cochrane systematic evaluation method was used to evaluate the quality of the included kinds of literature, and Revman5 software was used to sort out and analyze the kinds of literature. Meta-analysis showed that there was a statistical difference between the experimental group and the control group in case fatality rate (OR = 1.76, 95% CI (1.29, 2.39), P=0.0003, I² = 0%, Z = 3.58), adverse events (OR = 2.38, 95% CI (1.65, 3.45), P < 0.00001, I² = 0%, Z = 4.60), incidence of joint hemorrhage (OR = 2.52, 95% CI (1.62, 3.91), P < 0.00001, I² = 0%, Z = 4.12), incidence of subcutaneous stasis (OR = 1.76, 95% CI (1.26, 2.45), P=0.0009, I² = 5%, Z = 3.33), and hematoma volume (OR = 1.78, 95% CI (1.32, 2.40), P=0.0001, I² = 23%, Z = 3.80). DNA methylation in the promoter region of the coagulation factor vWF gene was significantly associated with the risk of unexplained recurrent hemophilia. Whether demethylation can improve the bleeding index of patients with recurrent hemophilia remains to be further explored.

Health and treatment outcomes of patients with hemophilia in the Netherlands, 1972-2019

INTRODUCTION

We conducted six cross-sectional nationwide questionnaire studies among all patients with hemophilia in the Netherlands from 1972 until 2019 to assess how health outcomes have changed, with a special focus on patients >50 years of age.

METHODS

Data were collected on patient characteristics, treatment, (joint) bleeding, joint impairment, hospitalizations, human immunodeficiency virus and hepatitis C infections, and general health status (RAND-36).

RESULTS

In 2019, 1009 patients participated, of whom 48% had mild, 15% moderate, and 37% severe hemophilia. From 1972 to 2019, the use of prophylaxis among patients with severe hemophilia increased from 30% to 89%. Their median annual bleeding rate decreased from 25 to 2 bleeds. Patients with severe hemophilia aged <16 years reported joint impairment less often over time, but in those aged >40 years joint status did not improve. In 2019, 5% of all 1009 patients were positive for the human immunodeficiency virus. The proportion of patients with an active hepatitis C infection drastically decreased from 45% in 2001 to 2% in 2019 due to new anti-hepatitis C treatment options. Twenty-five percent had significant liver fibrosis even after successful therapy. Compared to the general male population, patients aged >50 years reported much lower scores on the RAND-36, especially on physical functioning.

DISCUSSION/CONCLUSION

Our study shows that increased use of prophylactic treatment and effective hepatitis C treatment have improved joint health and nearly eradicated hepatitis C infection in patients with hemophilia in the Netherlands. However, patients still suffer from hemophilia-related complications, especially patients aged >50 years.

Structure of Blood Coagulation Factor VIII in Complex With an Anti-C2 Domain Non-Classical, Pathogenic Antibody Inhibitor

Factor VIII (fVIII) is a procoagulant protein that binds to activated factor IX (fIXa) on platelet surfaces to form the intrinsic tenase complex. Due to the high immunogenicity of fVIII, generation of antibody inhibitors is a common occurrence in patients during hemophilia A treatment and spontaneously occurs in acquired hemophilia A patients. Non-classical antibody inhibitors, which block fVIII activation by thrombin and formation of the tenase complex, are the most common anti-C2 domain pathogenic inhibitors in hemophilia A murine models and have been identified in patient plasmas. In this study, we report on the X-ray crystal structure of a B domain-deleted bioengineered fVIII bound to the non-classical antibody inhibitor, G99. While binding to G99 does not disrupt the overall domain architecture of fVIII, the C2 domain undergoes an ~8 Å translocation that is concomitant with breaking multiple domain-domain interactions. Analysis of normalized B-factor values revealed several solvent-exposed loops in the C1 and C2 domains which experience a decrease in thermal motion in the presence of inhibitory antibodies. These results enhance our understanding on the structural nature of binding non-classical inhibitors and provide a structural dynamics-based rationale for cooperativity between anti-C1 and anti-C2 domain inhibitors.

Assessing the potential cost-effectiveness of a gene therapy for the treatment of hemophilia A

Aim: Hemophilia A is a genetic, chronic disorder classified by deficient or defective coagulation factor VIII (FVIII) that puts those affected at risk for spontaneous bleeding episodes, which lead to joint damage and chronic pain over time. Currently, most severe hemophilia A patients are treated with prophylactic FVIII, which requires costly and frequent infusions and life-long adherence to medication. A gene therapy (valoctocogene roxaparvovec) is currently in development for the treatment of severe hemophilia A. This model assessed the potential cost-effectiveness of treating patients with valoctocogene roxaparvovec rather than prophylactic therapy.Materials and methods: We developed an individual-based, state-transition microsimulation model for assessing the likely cost-effectiveness of valoctocogene roxaparvovec compared to prophylactic FVIII. Men aged 30 with severe hemophilia A were modeled over a lifetime horizon, and costs were reported from the perspective of the United States health care system. Through microsimulation, patient-level heterogeneity was captured in starting weight, starting Pettersson score (PS), durability of valoctocogene roxaparvovec, and annual bleed rate (ABR).Results: The model projects that treatment with single-administration valoctocogene roxaparvovec would be cost-saving to people with hemophilia A at a price point comparable to other currently available gene therapy products due to its potential to reduce FVIII utilization, direct medical costs, lifetime bleeds, and accumulated joint damage.Limitations: The model relies upon evidence-based assumptions for clinical inputs due to limited data availability. Such uncertainty was mitigated by modeling heterogeneity across the population, specifically with regards to long-term gene therapy durability, lifetime bleed rates, and joint damage progression.Conclusion: Valoctocogene roxaparvovec was found to be cost-saving-on average by about $6.8 million per patient-and more effective than prophylactic therapy for treatment of hemophilia A. The comparative benefit of gene therapy was observed across a broad range of simulated patients that were representative of the real-world severe hemophilia A population.

Economic impact model of delayed inhibitor development in patients with hemophilia a receiving emicizumab for the prevention of bleeding events

Aims: Cumulative exogenous factor VIII (FVIII) exposure is an important predictor of developing neutralizing antibodies (inhibitors) to FVIII in patients with persons with hemophilia A (PwHA). The aim of this study was to model the costs of emicizumab versus FVIII prophylaxis and total treatment costs for patients with severe HA.Materials and Methods: An Excel-based decision model was developed to calculate cumulative costs in PwHA over a 20-year time horizon from the US payer perspective. The model considered persons with severe HA beginning at age 12 months with no prior FVIII exposure and initiating prophylaxis with emicizumab or FVIII. PwHA could develop inhibitors on accumulation of 20 FVIII exposure days. PwHA with inhibitors replaced FVIII with bypassing agents until inhibitors resolved spontaneously, following immune tolerance induction (ITI), or at the end of the time horizon. The primary model outcome was the difference in emicizumab versus FVIII treatment costs in 2019 USD. Sensitivity analyses were performed to test the robustness of results.Results: Total incremental cost over 20 years was -$1,945,480 (emicizumab arm, $4,919,058; FVIII arm, $6,864,538). Prophylaxis costs (emicizumab arm, $4,096,105; FVIII arm, $6,290,919) comprised the majority of costs in both groups, followed by breakthrough bleed treatment for the FVIII arm ($342,652) and ITI costs for the emicizumab arm ($733,671). Higher costs in the FVIII group reflected earlier inhibitor development (FVIII, 4 months; emicizumab, 162 months) and switch to bypassing agents.Limitations: The model design reflects a simplified treatment pathway for patients with severe HA who initiate FVIII or emicizumab prophylaxis. In the absence of clinical data, a key conservative assumption of the model is that patients receiving emicizumab and FVIII prophylaxis have the same risk of developing inhibitors.Conclusions: This study suggests that prophylaxis with emicizumab results in cost savings compared to FVIII prophylaxis in HA.

Safety of recombinant coagulation factors in treating hemophilia

INTRODUCTION

During the last decade, new FVIII/IX concentrates have been developed for the treatment of patients affected by hemophilia A/B. Significant progress has been achieved regarding their half-life, but the old issue of immunogenicity and new concerns about safety need to be addressed.

AREAS COVERED

After the implementation of virucidal methods, both plasma-derived and recombinant clotting factor concentrates achieved a very safe profile. The development of anti-FVIII antibodies is the major adverse event of replacement therapy with both FVIII concentrates. Furthermore, the new extended half-life concentrates, protein fused or pegylated, raised some concerns about their side effects.

EXPERT OPINION

The treatment of hemophilia A with inhibitors by induction of immunotolerance and using by-passing concentrates, improved the quality of life of patients but did not allow them to have a life expectancy like that of patients without inhibitors. The new humanized monoclonal antibody (MAb) ACE910, mimicking FVIII function, seems to be able to reduce the bleedings of hemophilia A patients with inhibitors. The post-marketing surveillance will clarify if the adverse events observed during the phase III clinical trials and compassionate use were due to the association with a Prothrombin activated complex concentrate or to the prothrombotic effect of the drug itself.

How I approach: Previously untreated patients with severe congenital hemophilia A

Previously untreated patients with severe hemophilia A are a vulnerable population at risk for severe bleeding which is currently managed with exogenous clotting factor replacement. The primary burden of current treatment is high-titer inhibitor development. Evolving data on current treatment products as well as emerging therapeutics may inform treatment decisions to prevent bleeding and inhibitor formation. Considerations for diagnosis, education, and shared decision-making related to product choice and treatment regimen are discussed.