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

Expert Opinions on the Management of Hemophilia A in India: The Role of Emicizumab

Hemophilia A (HA) is a genetic disorder of hemostasis associated with a deficiency or reduced activity of clotting factor VIII (FVIII). This disorder remains unacceptably underdiagnosed in India. Early diagnosis and appropriate management of HA can substantially prevent morbidity and mortality. Currently, HA is managed with regular replacement therapy using standard or extended half-life FVIII concentrates or non-factor drug products. The challenges associated with FVIII concentrates include plateauing of drug effect, issues with its administration and adherence to treatment, breakthrough bleeds, and the development of inhibiting antibodies against administered clotting factors. Emicizumab is a bispecific antibody, launched in India in April 2019, for managing patients with HA. To investigate the role of emicizumab in Indian patients with HA, opinions were sought from 13 eminent hematologists and experts from India on the effectiveness of emicizumab in preventing all bleeds, spontaneous bleeds, perioperative bleeds, and intracranial hemorrhage; resolving target joints; and reducing the rate of hospitalizations and fatality associated with HA in children and adults, with or without inhibitors. The benefits of emicizumab over traditional FVIII concentrates include the subcutaneous route of delivery, less frequent dosing, and a lack of inhibitor development, in addition to providing sustained hemostasis without in-depth monitoring. It is a safe and effective management option for all HA patients, especially for patients with certain archetypes, such as those with inhibitors, those with high annualized bleed rates, those living far away from hemophilia care centers, pediatric patients and infants with intravenous access challenges, and those with a history of life-threatening bleeding events.

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.

Cost-effectiveness analysis of emicizumab prophylaxis in patients with haemophilia A in India

INTRODUCTION

Emicizumab is the initial subcutaneously administered bispecific antibody approved as a prophylactic treatment for patients with haemophilia A (PwHA).

AIM

This study assessed the economic evaluation of emicizumab treatment for non-inhibitor severe haemophilia A (HA) patients in India.

METHODS

A Markov model evaluated the cost-effectiveness of emicizumab prophylaxis compared to on-demand therapy (ODT), low-dose prophylaxis (LDP; 1565 IU/kg/year), intermediate-dose prophylaxis (IDP; 3915 IU/kg/year) and high-dose prophylaxis (HDP; 7125 IU/kg/year) for HA patients without factor VIII inhibitors. Inputs from HAVEN-1 and HAVEN-3 trials included transition probabilities of different bleeding types. Costs and benefits were discounted at a 3.5% annual rate.

RESULTS

In the base-case analysis, emicizumab was cost-effective compared to HDP, with an incremental cost-effectiveness ratio (ICER) per quality-adjusted life-years (QALY) of Indian rupees (INR) 27,869. Compared to IDP, ODT and LDP, emicizumab prophylaxis could be considered a cost-effective option if the paying threshold is >1 per capita gross domestic product (GDP) with ICER/QALY values of INR 264,592, INR 255,876 and INR 305,398, respectively. One-way sensitivity analysis (OWSA) highlighted emicizumab cost as the parameter with the greatest impact on ICERs. Probabilistic sensitivity analysis (PSA) indicated that emicizumab had a 94.7% and 49.4% probability of being cost-effective at willingness-to-pay (WTP) thresholds of three and two-times per capita GDP.

CONCLUSION

Emicizumab prophylaxis is cost-effective compared to HDP and provides value for money compared to ODT, IDP, and LDP for severe non-inhibitor PwHA in India. Its long-term humanistic, clinical and economic benefits outweigh alternative options, making it a valuable choice in resource-constrained settings.

Non-clotting factor therapies for preventing bleeds in people with congenital hemophilia A or B

BACKGROUND

Management of congenital hemophilia A and B is by prophylactic or on-demand replacement therapy with clotting factor concentrates. The effects of newer non-clotting factor therapies such as emicizumab, concizumab, marstacimab, and fitusiran compared with existing standards of care are yet to be systematically reviewed.

OBJECTIVES

To assess the effects (clinical, economic, patient-reported, and adverse outcomes) of non-clotting factor therapies for preventing bleeding and bleeding-related complications in people with congenital hemophilia A or B compared with prophylaxis with clotting factor therapies, bypassing agents, placebo, or no prophylaxis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, electronic databases, conference proceedings, and reference lists of relevant articles and reviews. The date of the last search was 16 August 2023.

SELECTION CRITERIA

Randomized controlled trials (RCTs) evaluating people with congenital hemophilia A or B with and without inhibitors, who were treated with non-clotting factor therapies to prevent bleeds.

DATA COLLECTION AND ANALYSIS

Two review authors independently reviewed studies for eligibility, assessed risk of bias, and extracted data for the primary outcomes (bleeding rates, health-related quality of life (HRQoL), adverse events) and secondary outcomes (joint health, pain scores, and economic outcomes). We assessed the mean difference (MD), risk ratio (RR), 95% confidence interval (CI) of effect estimates, and evaluated the certainty of the evidence using GRADE.

MAIN RESULTS

Six RCTs (including 397 males aged 12 to 75 years) were eligible for inclusion. Prophylaxis versus on-demand therapy in people with inhibitors Four trials (189 participants) compared emicizumab, fitusiran, and concizumab with on-demand therapy in people with inhibitors. Prophylaxis using emicizumab likely reduced annualized bleeding rates (ABR) for all bleeds (MD -22.80, 95% CI -37.39 to -8.21), treated bleeds (MD -20.40, 95% CI -35.19 to -5.61), and annualized spontaneous bleeds (MD -15.50, 95% CI -24.06 to -6.94), but did not significantly reduce annualized joint and target joint bleeding rates (AjBR and AtjBR) (1 trial; 53 participants; moderate-certainty evidence). Fitusiran also likely reduced ABR for all bleeds (MD -28.80, 95% CI -40.07 to -17.53), treated bleeds (MD -16.80, 95% CI -25.80 to -7.80), joint bleeds (MD -12.50, 95% CI -19.91 to -5.09), and spontaneous bleeds (MD -14.80, 95% CI -24.90 to -4.71; 1 trial; 57 participants; moderate-certainty evidence). No evidence was available on the effect of bleed prophylaxis using fitusiran versus on-demand therapy on AtjBR. Concizumab may reduce ABR for all bleeds (MD -12.31, 95% CI -19.17 to -5.45), treated bleeds (MD -10.10, 95% CI -17.74 to -2.46), joint bleeds (MD -9.55, 95% CI -13.55 to -5.55), and spontaneous bleeds (MD -11.96, 95% CI -19.89 to -4.03; 2 trials; 78 participants; very low-certainty evidence), but not target joint bleeds (MD -1.00, 95% CI -3.26 to 1.26). Emicizumab prophylaxis resulted in an 11.31-fold increase, fitusiran in a 12.5-fold increase, and concizumab in a 1.59-fold increase in the proportion of participants with no bleeds. HRQoL measured using the Haemophilia Quality of Life Questionnaire for Adults (Haem-A-QoL) physical and total health scores was improved with emicizumab, fitusiran, and concizumab prophylaxis (low-certainty evidence). Non-serious adverse events were higher with non-clotting factor therapies versus on-demand therapy, with injection site reactions being the most frequently reported adverse events. Transient antidrug antibodies were reported for fitusiran and concizumab. Prophylaxis versus on-demand therapy in people without inhibitors Two trials (208 participants) compared emicizumab and fitusiran with on-demand therapy in people without inhibitors. One trial assessed two doses of emicizumab (1.5 mg/kg weekly and 3.0 mg/kg bi-weekly). Fitusiran 80 mg monthly, emicizumab 1.5 mg/kg/week, and emicizumab 3.0 mg/kg bi-weekly all likely resulted in a large reduction in ABR for all bleeds, all treated bleeds, and joint bleeds. AtjBR was not reduced with either of the emicizumab dosing regimens. The effect of fitusiran prophylaxis on target joint bleeds was not assessed. Spontaneous bleeds were likely reduced with fitusiran (MD -20.21, 95% CI -32.12 to -8.30) and emicizumab 3.0 mg/kg bi-weekly (MD -15.30, 95% CI -30.46 to -0.14), but not with emicizumab 1.5 mg/kg/week (MD -14.60, 95% CI -29.78 to 0.58). The percentage of participants with zero bleeds was higher following emicizumab 1.5 mg/kg/week (50% versus 0%), emicizumab 3.0 mg/kg bi-weekly (40% versus 0%), and fitusiran prophylaxis (40% versus 5%) compared with on-demand therapy. Emicizumab 1.5 mg/kg/week did not improve Haem-A-QoL physical and total health scores, EQ-5D-5L VAS, or utility index scores (low-certainty evidence) when compared with on-demand therapy at 25 weeks. Emicizumab 3.0 mg/kg bi-weekly may improve HRQoL measured by the Haem-A-QoL physical health score (MD -15.97, 95% CI -29.14 to -2.80) and EQ-5D-5L VAS (MD 9.15, 95% CI 2.05 to 16.25; 1 trial; 43 participants; low-certainty evidence). Fitusiran may result in improved HRQoL shown as a reduction in Haem-A-QoL total score (MD -7.06, 95% CI -11.50 to -2.62) and physical health score (MD -19.75, 95% CI -25.76 to -11.94; 1 trial; 103 participants; low-certainty evidence). The risk of serious adverse events in participants without inhibitors also likely did not differ following prophylaxis with either emicizumab or fitusiran versus on-demand therapy (moderate-certainty evidence). Transient antidrug antibodies were reported in 4% (3/80) participants to fitusiran, with no observed effect on antithrombin lowering. A comparison of the different dosing regimens of emicizumab identified no differences in bleeding, safety, or patient-reported outcomes. No case of treatment-related cancer or mortality was reported in any study group. None of the included studies assessed our secondary outcomes of joint health, clinical joint function, and economic outcomes. None of the included studies evaluated marstacimab.

AUTHORS' CONCLUSIONS

Evidence from RCTs shows that prophylaxis using non-clotting factor therapies compared with on-demand treatment may reduce bleeding events, increase the percentage of individuals with zero bleeds, increase the incidence of non-serious adverse events, and improve HRQoL. Comparative assessments with other prophylaxis regimens, assessment of long-term joint outcomes, and assessment of economic outcomes will improve evidence-based decision-making for the use of these therapies in bleed prevention.

Emicizumab state-of-the-art update

Introduction

Emicizumab is a bispecific monoclonal antibody developed to address the unmet needs of clotting factor replacement therapy and has become the benchmark for optimal prophylaxis in managing patients with haemophilia A with inhibitors. We describe the emicizumab rollout and pharmacokinetic strategies and their use in paediatric patients.

Methods

The evolving real‐world experience in using emicizumab has confirmed its safety, efficacy and pharmacokinetic profile in paediatric, adolescent and adult patients receiving emicizumab at various prophylactic dosing regimens. The emicizumab current global rollout includes over 100 countries with 29 low to middle‐income countries accessing emicizumab through the World Federation of Haemophilia (WFH) Humanitarian Aid Program. The diversity of emicizumab dosing and pharmacokinetic tools such as the Calibra® and the WAPPS‐Hemo platforms make it possible to achieve prophylaxis goals in line with the WFH Haemophilia treatment guidelines recommendations, with minimal drug wastage. The emerging experience from long term clinical trials and long‐term real‐world follow‐up confirm the safety, efficacy, and pharmacokinetic profile of emicizumab in paediatric haemophilia A patients. A few questions, including inhibitor recurrence, concurrent use of emicizumab with various replacement therapies and inhibitor eradication, are being addressed through multiple ongoing clinical studies.

Conclusion

The current global rollout of emicizumab is remarkable, and versatile dosing regimens and evolving pharmacokinetic tools such as the Calibra® and WAPPS‐Hemo platforms make it a treatment choice available also for pharmacokinetic guided personalised treatment. Data from paediatric studies are consistent with those seen in adolescent and adult Haemophilia A.

Inhibitors: Diagnostic challenges, unknowns of inhibitor development, treatment of bleeding and surgery, and insights into diagnosis and treatment in China

Factor (F) VIII inhibitors develop in around 30% of previously untreated patients (PUPs) with severe haemophilia, to a lesser extend in moderate and mild haemophilia A and in up to 10% in severe haemophilia B. Diagnostic challenges and questions remain including access to high quality testing, the role for functional inhibitor testing and binding antibody testing, and the adaptations needed in the presence of non-factor replacement therapy. Despite significant gains in knowledge there are still many unanswered questions underlying the immunologic mechanisms of inhibitor development and tolerance. Therapeutic options include eradication of inhibitors using immune tolerance induction therapy (ITI), prophylaxis with bypassing agents (i.e., recombinant activated factor VII /rFVIIa or activated prothrombin complex concentrate/aPCC) or non-factor replacement therapies (e.g., emicizumab) and treatment of bleeds or coverage of surgeries/invasive procedure. Recently a haemophilia centre capacity building program was launched in China to further develop the infrastructure and support needed to improve the diagnosis of haemophilia, detection of inhibitors, and continue to improve the care of patients with haemophilia and inhibitors.

Cost-minimization analysis of recombinant factor VIII Fc versus emicizumab for treating patients with hemophilia A without inhibitors in Europe

BACKGROUND AND OBJECTIVE

A cost-minimization model was developed to compare recombinant factor VIII Fc (rFVIIIFc) and emicizumab as prophylaxis for hemophilia A without inhibitors.

METHODS

The model was based on 100 patients from the healthcare payer perspective in the UK, France, Italy, Spain, and Germany (5-year time horizon). Costs included: drug acquisition; emicizumab wastage by bodyweight (manufacturer's dosing recommendations); and additional FVIII for breakthrough bleeds. Scenario analyses (UK only): reduced emicizumab dosing frequency; and emicizumab maximum wastage.

RESULTS

Total incremental 5-year savings for rFVIIIFc rather than emicizumab use range from €89,320,131 to €149,990,408 in adolescents/adults (≥12 years) and €173,417,486 to €253,240,465 in children (<12 years). Emicizumab wastage accounts for 6% of its total cost in adolescents/adults and 26% in children. Reducing the emicizumab dosing frequency reduces the incremental cost savings with rFVIIIFc, but these remain substantial (adolescents/adults, >€92 million; children >€32 million). Maximum emicizumab wastage increases by 86% and 106%, respectively, increasing the incremental cost savings with rFVIIIFc to €125,352,125 and €105,872,727, respectively.

CONCLUSION

Based on cost-minimization modeling, rFVIIIFc use for hemophilia A prophylaxis in patients without inhibitors is associated with substantial cost savings in Europe, reflecting not only higher acquisition costs of emicizumab, but also other costs including wastage related to available vial sizes.

Management of children with hemophilia A: How emicizumab has changed the landscape

The key to having a good quality of life for an adult with hemophilia rests largely on how he or she was managed as children. With effective prophylaxis, young men can begin their adult life with excellent joint function and few, if any, other sequelae from their disease. Unfortunately, this outcome is not always (nor often) attained because of the limitations of the mainstay of treatment, which is factor replacement therapy. In resource-rich countries with an adequate supply of factor concentrates, the treatment burden and formation of inhibitors limit the potential for an ideal outcome, whereas in much of the world, factor concentrates are too expensive to even be an option. The novel agent, emicizumab, which has become available in numerous countries around the world, is reshaping how one approaches the treatment of children with hemophilia A. This Forum Article, based on a State-of-the-Art lecture given at the 2020 International Society on Thrombosis and Haemostasis Virtual Meeting, presents an approach including clinically applicable algorithms for treating children with hemophilia A in the new era with emicizumab.

Bleeding outcomes and factor utilization after switching to an extended half-life product for prophylaxis in haemophilia A in Austria

To prevent bleeding in severe haemophilia A [SHA, defined as factor VIII (FVIII) activity < 1%] regular prophylactic FVIII replacement therapy is required, and the benefits of factor products with extended half-life (EHL) over traditional standard half-life (SHL) are still being debated. We performed a multi-centre, retrospective cohort study of persons with SHA in Austria aiming to compare clinical outcomes and factor utilization in patients with SHA, who switched from prophylaxis with SHL to an EHL. Data were collected from haemophilia-specific patient diaries and medical records. Twenty male persons with SHA (median age: 32.5 years) were included. The most common reason for switching to the EHL was a high bleeding rate with SHL. Switch to rFVIII-Fc resulted in a significantly decreased annualized bleeding rate (ABR; median difference (IQR): − 0.3 (− 4.5–0); Wilcoxon signed-rank test for matched pairs: Z = − 2.7, p = 0.008) and number of prophylactic infusions per week (− 0.75 (− 1.0–0.0); Z = − 2.7, p = 0.007). Factor utilization was comparable to prior prophylaxis with SHL (0.0 (− 15.8–24.8) IU/kg/week; Z = − 0.4, p = 0.691). In summary, switch to EHL (rFVIII-Fc) was associated with an improved clinical outcome, reflected by ABR reduction, and less frequent infusions, without significantly higher factor usage.

Costs of the management of hemophilia A with inhibitors in Spain

Introduction

Emicizumab is a first-in-class monoclonal antibody, recently authorized for the treatment of hemophilia A with inhibitors. This study aims to estimate the direct and indirect costs of the management of hemophilia A with inhibitors, in adult and pediatric patients, including the prophylaxis with emicizumab.

Methods

We calculated the costs of the on-demand and prophylactic treatments with bypassing agents (activated prothrombin complex concentrate and recombinant activated factor VII) and the emicizumab prophylaxis, from the societal perspective, over 1 year. The study considered direct healthcare costs (drugs, visits, tests, and hospitalizations), direct non-healthcare costs (informal caregivers), and indirect costs (productivity loss). Data were obtained from a literature review and were validated by an expert group. Costs were expressed in 2019 euros.

Results

Our results showed that the annual costs of the prophylactic treatment per patient varied between €543,062.99 and €821,415.77 for adults, and €182,764.43 and €319,826.59 for children, while on-demand treatment was €532,706.84 and €789,341.91 in adults, and €167,523.05 and €238,304.71 in pediatric patients. In relation to other prophylactic therapies, emicizumab showed the lowest costs, with up to a 34% and 43% reduction in the management cost of adult and pediatric patients, respectively. It reduced the bleeding events and administration costs, as this drug is less frequently administered by subcutaneous route. Emicizumab prophylaxis also decreased the cost of other healthcare resources such as visits, tests, and hospitalizations, as well as indirect costs.

Conclusion

In comparison to prophylaxis with bypassing agents, emicizumab reduced direct and indirect costs, resulting in cost savings for the National Health System and society.

The societal burden of haemophilia A. III - The potential impact of emicizumab on costs of haemophilia A in Australia

INTRODUCTION

Emicizumab is a humanized monoclonal modified IgG4 antibody with bispecific antibody structure bridging Factor IXa and Factor X. Emicizumab has demonstrated efficacy and safety in adults, adolescents and paediatrics with HA, with or without inhibitors to Factor VIII (FVIII). There is currently no evidence that reports on the potential impact of the introduction of emicizumab on the societal costs of haemophilia A (HA). The purpose of this study was to explore the cost impact associated with the introduction of emicizumab on the current societal costs of people with HA (PwHA) in Australia.

METHODS

We conducted an analysis of the impact of emicizumab on societal costs, based on changes in the direct and indirect costs incurred by PwHA. Potential impacts of emicizumab on outcomes in PwHA were modelled based on HAVEN 1, HAVEN 2 and HAVEN 3 studies. We assumed that eligible PwHA commenced use of emicizumab on 1 January 2018. The impact of emicizumab on costs of HA in Australia males was then estimated for the 12-month period to 31 December 2018.

RESULTS

Overall, uptake of emicizumab in its first year of use reduces annual costs associated with moderate/severe HA by AUD$69.197M (62.3%). This reflects 64.2% reduction in the cost of FVIII blood products and 92% reduction in cost of bypassing agents.

CONCLUSION

The cost of emicizumab is likely to offset some or all of the projected reductions in treatment costs. However, we also found 30.7% reduction in non-treatment direct costs (AUD$3.771M) and 19.1% reduction in indirect costs (AUD$2.732M).

Cost-utility analysis of emicizumab prophylaxis in haemophilia A patients with factor VIII inhibitors in Korea

AIMS

Haemophilia A patients with factor VIII inhibitors (HAPI) experience frequent spontaneous bleeding, approximately once a week, and require expensive bypassing agent (BPA) treatments to control bleeding over their lifetime. According to the HAVEN 1 trial, weekly emicizumab (Hemlibra®) prophylaxis injection reduces annualized bleeding rates (ABR) by 87% compared with BPA on-demand treatment (BPA-OD) administered at the time of bleeding. Our study aimed to assess the cost-effectiveness of emicizumab prophylaxis in HAPI in Korea.

METHODS

Using a lifetime Markov model with health states of 'alive with bleeds' and 'dead', we simulated the experience of HAPI receiving emicizumab prophylaxis (treatment arm) or BPA-OD (control arm) and estimated expected clinical and economic outcomes under each treatment arm. Model parameters included comparative effectiveness, clinical and epidemiologic characteristics of Korean HAPI, costs of drug treatment and medical events and utility for 'alive with bleeds' state under each treatment. We utilized local data, including National Health Insurance claims data, national statistics, literature and expert surveys with haematologists.

RESULTS

Base-case analysis results showed that compared with BPA-OD, lifetime emicizumab prophylaxis prevented 807 bleedings, extended 3.04 quality-adjusted life-years and reduced costs by 2.6 million US dollars. Thus, emicizumab prophylaxis is a dominant treatment option with better effectiveness and lower costs than BPA-OD. A series of one-way sensitivity analyses consistently showed dominant results, confirming that lifetime emicizumab prophylaxis is a cost-saving intervention for HAPI.

CONCLUSION

Emicizumab prophylaxis is an excellent treatment choice reducing ABR, improving quality of life and reducing costs.

Substitution therapy

Emicizumab is a bispecific antibody that recognizes FIX(a)/FX, and mimics FVIIIa cofactor activity. Due to its unique characteristics including longer half-life and subcutaneous injectability, treatment for haemophilia A dramatically improved regardless of the presence of FVIII inhibitor. Protection from pathological change in joints, avoidance of inhibitor development and intra-cranial haemorrhage could be expected by introduction of emicizumab in early childhood. Applications in mild/moderate patients should be also considered. Clinical assessment tool should be standardized; however, since there are limitations to conventional ABR-based assessment. Laboratory monitoring is another practical issue due to the mode of action of emicizumab. Chromogenic assays and global assays could be utilized. The other emicizumab-related practical issue is immune tolerance induction for the inhibitor patients, since ITI remains the only effective means to inhibitor eradication. With the recently introduced Atlanta protocol, emicizumab prophylaxis is given in combination with 50-100 IU/kg FVIII three times a week. A single manuscript has been published, and multiple clinical trials are open to address the efficacy of this strategy. Whether the Atlanta protocol will be fully embraced is yet to be seen, but there is widespread consensus about attempts to tolerize every haemophilia A patient with an inhibitor.