Switching from standard to extended half-life FVIII prophylaxis in haemophilia A: Comparison of factor product use, bleed rates and pharmacokinetics

Changes in Hemophilia Treatment in the Eastern Part of Germany between 2015 and 2021-Data from the Kompetenznetz Hämorrhagische Diathese Ost (KHDO)

INTRODUCTION

 Treatment options for patients with hemophilia (PWH) have changed substantially in the last years. This study aimed to compare hemophilia treatment in the eastern part of Germany in 2021 with data from 2015.

METHODS

 Substitution diaries and patient records of PWH from 2021 were collected in 13 hemophilia centers from the "Kompetenznetz Hämorrhagische Diathese Ost" (KHDO) and compared with 2015.

RESULTS

 A total of 130 children and 357 adults, 411 hemophilia A (HA) and 76 hemophilia B (HB), were included in 2021, and 359 were already analyzed in 2015. In 2021, 97.8% of children and 95.7% of adults with severe hemophilia had prophylaxis compared with 98.8 and 80.2% in 2015. Plasma-derived concentrates were used in 25.6%, recombinant in 30.2%, extended half-life (EHL) factor concentrates in 24.4%, and emicizumab in 19.8% of the children with severe HA (sHA). In adults with sHA, plasma-derived, recombinant concentrates, EHL, and emicizumab were used in 21.0, 33.2, 31.2, and 14.2%, respectively. All children and 93.3% of the adults with severe HB (sHB) were on EHL. Median annual factor consumption per body weight increased in adults with sHA, remained stable in children with sHA and adults with sHB, and decreased in children with sHB between 2015 and 2021. Annualized bleeding rate (ABR) decreased in children with sHB and sHA.

CONCLUSION

 The use of EHL and emicizumab has changed hemophilia treatment. About 50% of the sHA patients switched to EHL or emicizumab and almost all sHB patients to EHL. More adults with sHA received prophylaxis and ABR decreased in children.

[Translated article] Pharmacokinetic-guided switching from standard half-life factor VIII to extended half-life pegylated factor VIII in haemophilia A therapy in clinical practice

OBJECTIVE

To analyse the differences in pharmacokinetic and clinical parameters (bleeding rates and joint health) before and after switching from standard half-life factor VIII (FVIII) to extended half-life pegylated FVIII in patients with severe/moderate haemophilia A on prophylaxis, 1 year before and after the switch in real-life.

METHOD

This is a single-centre, comparative, observational, sequential, retrospective, and multidisciplinary study. Population pharmacokinetic models from the WAPPS-Hemo® application were used to calculate pharmacokinetic parameters and individualise prophylaxis. The annual rate of total and joint bleeds, joint health (Haemophilia Joint Health Score), plasma half-life and area under the curve ratios, FVIII consumption, administration frequency, and cost were analysed.

RESULTS

Thirty-eight adult patients with haemophilia A who switched from standard half-life FVIII to extended half-life pegylated FVIII were analysed. Significant improvements (P < .05) were observed in all pharmacokinetic parameters, with plasma half-life and area under the curve improvement ratios of 1.5 and 1.9, respectively, as well as reductions in annual total and joint bleeding rates. A higher number of patients with zero total (16.0 vs. 29.0) and joint bleeds (23.0 vs. 33.0) was also observed. The median reductions in administration frequency and dose/kg/week were 30.0% and 19.7%, respectively, avoiding 44.3 infusions/patient/year, resulting in savings of 20,843 €/patient/year. Furthermore, joint health improved (23.0 vs. 21.0; P = .017), and target joints resolved after the switch.

CONCLUSIONS

The pharmacokinetically guided switch from standard half-life FVIII to pegylated FVIII demonstrated significant clinical benefits with reduced bleeding rates and improvements in joint health. Additionally, improvements in pharmacokinetic parameters were observed, allowing for reduced treatment burden by decreasing administration frequency, as well as lower consumption and costs.

International Society on Thrombosis and Haemostasis Clinical Practice Guideline for Treatment of Congenital Haemophilia-A Critical Appraisal

INTRODUCTION

Evidence-based clinical practice guidelines drive optimal patient care and facilitate access to high-quality treatment. Creating guidelines for rare diseases such as haemophilia, where evidence does not often come from randomized controlled trials but from non-randomized and well-designed observational studies and real-world data, is challenging. The methodology used for assessing available evidence should consider this critical fact. In formulating guidelines, it is essential to include treatment goals and patient preference.

AIM

This paper comprehensively critiques, against this background, the recommendations of the ISTH clinical practice guidelines for the treatment of haemophilia.

METHODS

Each recommendation was critically reviewed against available evidence as well as existing guidelines and commented upon for its scientific validity, impact on clinical practice and access to care globally. The validity of the way in which the GRADE methodology was applied to existing evidence was also assessed.

RESULTS

The critique provided shows that these recommendations have major limitations: they did not state treatment goals and contradict existing guidelines; opportunities for providing access to innovation were missed when the therapeutic benefits of the products approved in the last decades were not included. A major reason for this is the inappropriate adoption of the GRADE methodology without adaptations and without considering treatment goals and patient-relevant outcomes.

CONCLUSION

These recommendations may mislead healthcare professionals, payers and governments and therefore cannot serve the patient community well. They setback the advances made in haemophilia care because they overlook important available evidence and do not guide clinical practice to contemporary standards.

An observational study of haemophilia A patients without inhibitors using the French national claims (SNDS) database

OBJECTIVES

To describe clinical characteristics, factor consumption, and events of interest in patients with haemophilia A without inhibitors receiving prophylaxis in France, and the clinical impact of switching to Elocta® in this population.

METHODS

This retrospective, observational study using the Système National des Données de Santé database, analysed data from patients with haemophilia A without inhibitors using prophylactic factor VIII (FVIII) replacement therapy during 2016-2019. Clinical characteristics, treatment patterns and switches, factor consumption, and rate of events of interest were determined. In a sub-cohort of patients treated with Elocta®, clinical characteristics, factor consumption, and rate of events of interest before and after switching to Elocta® were compared.

RESULTS

For 545 patients, with mean age (standard deviation [SD]) 25.4 (17.8) years, Elocta® was the most used treatment. Bleeding events and articular non-bleeding events leading to hospitalization occurred in 15.4% and 13.9% of patients, respectively, and 9.9% of patients had surgeries or procedures related to haemophilic arthropathy. The mean (SD) FVIII product consumption was 344 (93) IU/kg/month for extended half-life treatment, and 331 (98) IU/kg/month for standard half-life products. For the sub-cohort of 146 patients, bleeding events (SD) decreased from 0.32 (2.2) to 0.09 (0.42) events/patient/year (p = 0.227) after switching to Elocta®. There was no statistically significant difference in rates of factor consumption or articular non-bleeding events before and after initiation of Elocta®.

CONCLUSION

This study provides real-world insights that advance the understanding of treatment patterns and events of interest in patients with haemophilia A on prophylactic regimens in France.

Pharmacokinetic-guided switching from standard half-life factor VIII to extended half-life pegylated factor VIII in the therapy of hemophilia A in clinical practice

OBJECTIVE

To analyze the differences in pharmacokinetic and clinical parameters (bleeding rates and joint health) before and after switching from standard half-life factor VIII (FVIII) to extended half-life pegylated FVIII in patients with severe/moderate hemophilia A on prophylaxis, one year before and after the switch in real-life.

METHOD

This is a single-center, comparative, observational, sequential, retrospective, and multidisciplinary study. Population pharmacokinetic models from the WAPPS-Hemo® application were used to calculate pharmacokinetic parameters and individualize prophylaxis. The annual rate of total and joint bleeds, joint health (Hemophilia Joint Health Score), plasma half-life and area under the curve ratios, FVIII consumption, administration frequency, and cost were analyzed.

RESULTS

Thirty-eight adult patients with hemophilia A who switched from standard half-life FVIII to extended half-life pegylated FVIII were analyzed. Significant improvements (p < 0.05) were observed in all pharmacokinetic parameters, with plasma half-life and area under the curve improvement ratios of 1.5 and 1.9, respectively, as well as reductions in annual total and joint bleeding rates were registered. A higher number of patients with zero total (16.0 vs. 29.0) and joint bleeds (23.0 vs. 33.0) was also observed. The median reductions in administration frequency and dose/kg/week were 30.0% and 19.7%, respectively, avoiding 44.3 infusions/patient/year, resulting in savings of 20,843 €/patient/year. Furthermore, joint health improved (23.0 vs. 21.0; p = 0.017), and target joints resolved after the switch.

CONCLUSIONS

The pharmacokinetically guided switch from standard half-life FVIII to pegylated FVIII demonstrated significant clinical benefits with reduced bleeding rates and improvements in joint health. Additionally, improvements in pharmacokinetic parameters were observed, allowing for reduced treatment burden by decreasing administration frequency, as well as lower consumption and costs.

Development of a Coagulation Disorders Unit

Our Coagulation Disorders Unit in Helsinki, Finland, provides 24/7 services for local and national hospitals and colleagues upon requests regarding bleeding and thrombosis diagnostics and management, including follow-up. The unit has a tight connection between the clinic and laboratory, and its maintenance and sharing knowledge and observations have been priorities, already for over 20 years and will continue to be of major importance. The consultation service is provided by phone during daytime and on-call hours, and in written form sent electronically to the consulting stakeholders. Thrombosis and hemostasis-targeted outpatient clinics are also available for the patients referred to the center. Writing local guidance and official guidelines, Nordic, European and international collaboration, and educational activities including social communication are critical elements for the Coagulation Disorders Unit. Alertness to acute coagulation abnormalities, such as occurred during COVID-19 and vaccine-induced thrombosis and thrombocytopenia, and development of strategies to manage cross-disciplinary problems are topics which call upon broad networking. The Nordic community has an ongoing historical meeting, which has been circulating among coagulation centers for the past 56 years. At the European level, the European Association of Haemophilia and Allied Disorders focuses on bleeding disorders and their management, including safety surveillance. The International Society of Thrombosis and Haemostasis offers excellent basic and clinical benchmarks for any Coagulation Disorders Unit. We hope that the description of the development and implementation of our Coagulation Disorders Unit in Helsinki achieves international interest and broadens international collaboration. Finally, we congratulate STH on its great contributions around the globe and for providing a vivid forum to foster the discipline of thrombosis and hemostasis.

Moderate- to vigorous-intensity physical activities for hemophilia A patients during low-dose pharmacokinetic-guided extended half-life factor VIII prophylaxis

BACKGROUND

Low-dose pharmacokinetic (PK)-guided extended half-life (EHL) factor VIII (FVIII) prophylaxis can reduce the bleeding risk in hemophilia A (HA) patients. An increase in physical activities for promoting musculoskeletal health may enhance the benefits of prophylactic therapy.

OBJECTIVES

To determine the clinical impact of moderate- to vigorous-intensity physical activities in HA patients during low-dose PK-guided EHL FVIII prophylaxis.

PATIENTS/METHODS

This prospective study enrolled patients with moderate/severe HA (baseline FVIII levels ≤ 5 IU/dL) who had received low-dose PK-guided EHL FVIII prophylaxis for ≥ 6 months. An individualized exercise protocol was introduced to each participant, targeting a 65% increase in the maximum predicted heart rate for ≥ 150 min/week, while continuing low-dose PK-guided EHL FVIII prophylaxis for 6 months. Before and after implementing the intervention, annualized bleeding rates (ABR), annualized joint bleeding rates (AJBR), Hemophilia Joint Health Scores (HJHS), skeletal muscle mass, hemophilia-specific quality-of-life (QoL) scores and annualized FVIII consumption were compared.

RESULTS

Of 13 participants (mean age ± standard deviation [SD]: 20.1 ± 6.8 years), ABR, AJBR, and HJHS were significantly reduced (mean differences [MD] ± SD: -5.7 ± 2.6 bleeds/year, -4.2 ± 2.6 joint bleeds/year, and -4.3 ± 3.2 marks, respectively; P < 0.05) after applying the 6-month exercise protocol. Skeletal muscle mass and QoL scores had also improved (P = 0.001), while FVIII usage had decreased (MD ± SD: -129.1 ± 208.7 IU/kg/year; P < 0.05).

CONCLUSIONS

The combination of moderate- to vigorous-intensity physical activities with low-dose PK-guided EHL FVIII prophylaxis improves bleeding prevention, musculoskeletal status and QoL in patients with moderate/severe HA. By minimizing FVIII consumption, this strategy helps optimize hemophilia care in countries with budget constraints.

CLINICALTRIALS

gov NCT05728528.

Cellular stress and coagulation factor production: when more is not necessarily better

Remarkably, it has been 40 years since the isolation of the 2 genes involved in hemophilia A (HA) and hemophilia B (HB), encoding clotting factor (F) VIII (FVIII) and FIX, respectively. Over the years, these advances led to the development of purified recombinant protein factors that are free of contaminating viruses from human pooled plasma for hemophilia treatments, reducing the morbidity and mortality previously associated with human plasma-derived clotting factors. These discoveries also paved the way for modified factors that have increased plasma half-lives. Importantly, more recent advances have led to the development and Food and Drug Administration approval of a hepatocyte-targeted, adeno-associated viral vector-mediated gene transfer approach for HA and HB. However, major concerns regarding the durability and safety of HA gene therapy remain to be resolved. Compared with FIX, FVIII is a much larger protein that is prone to misfolding and aggregation in the endoplasmic reticulum and is poorly secreted by the mammalian cells. Due to the constraint of the packaging capacity of adeno-associated viral vector, B-domain deleted FVIII rather than the full-length protein is used for HA gene therapy. Like full-length FVIII, B-domain deleted FVIII misfolds and is inefficiently secreted. Its expression in hepatocytes activates the cellular unfolded protein response, which is deleterious for hepatocyte function and survival and has the potential to drive hepatocellular carcinoma. This review is focused on our current understanding of factors limiting FVIII secretion and the potential pathophysiological consequences upon expression in hepatocytes.

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.

Evaluation of treatment and outcome for patients with haemophilia A and haemophilia B on extended half-life (EHL) factor products: A 12-month data analysis

INTRODUCTION

Extended half-life (EHL) factor VIII and IX concentrates as prophylaxis against bleeds have been available to selected persons with haemophilia (PWH) in Australia since March 2018. Preliminary analysis of switching to EHL demonstrated increased treatment adherence, fewer injections and improved bleeding outcomes.

AIMS

To characterise clinical practices regarding the use of EHL in Australia, to further evaluate treatment regimens and bleeding outcomes, and to analyse the influence of EHL product pharmacokinetics on clinical decision-making.

METHODS

A national, retrospective study was conducted using the Australian Bleeding Disorders Registry (ABDR). Patients on EHL products during the entire 2019 calendar year were included for analysis.

RESULTS

A complete and validated dataset of 174 PWH was analysed, 115 Haemophilia A (HA) and 59 Haemophilia B (HB). Adherence to EHL therapy was 85.7% in HA and 87.2% in HB. About 63.5% of HA and 64.4% of HB PWH reported zero spontaneous bleeds over 12months. Ankles were the most frequent spontaneous bleed site. Approximately one-third patients underwent dose adjustments, with most frequent reasons being pharmacokinetics, body weight change and breakthrough bleeds. About 19.5% of PWH had target joint history, with spontaneous bleeds reported in 58% of that cohort on EHL. Multivariate regression showed significant impact of non-adherence, target joint history and short half-life on spontaneous bleeds in the HA cohort; however only short half-life had significant impact in the HB cohort.

CONCLUSION

EHL usage in Australia shows excellent treatment adherence and bleeding outcomes. This study affirms the use and value of widely available population-based pharmacokinetics as a clinical tool.

Current Understanding of Inherited Modifiers of FVIII Pharmacokinetic Variation

The inherited bleeding disorder hemophilia A involves the quantitative deficiency of the coagulation cofactor factor VIII (FVIII). Prophylactic treatment of severe hemophilia A patients with FVIII concentrates aims to reduce the frequency of spontaneous joint bleeding and requires personalized tailoring of dosing regimens to account for the substantial inter-individual variability of FVIII pharmacokinetics. The strong reproducibility of FVIII pharmacokinetic (PK) metrics between repeat analyses in the same individual suggests this trait is genetically regulated. While the influence of plasma von Willebrand factor antigen (VWF:Ag) levels, ABO blood group, and patient age on FVIII PK is well established, estimates suggest these factors account for less than 35% of the overall variability in FVIII PK. More recent studies have identified genetic determinants that modify FVIII clearance or half-life including VWF gene variants that impair VWF-FVIII binding resulting in the accelerated clearance of VWF-free FVIII. Additionally, variants in receptors that regulate the clearance of FVIII or the VWF-FVIII complex have been associated with FVIII PK. The characterization of genetic modifiers of FVIII PK will provide mechanistic insight into a subject of clinical significance and support the development of personalized treatment plans for patients with hemophilia A.