Recombinant factor VIII Fc for the treatment of haemophilia A

Efanesoctocog alfa: the renaissance of Factor VIII replacement therapy

Efanesoctocog alfa (Altuviiio,TM Sanofi-SOBI) is a B domain-deleted single-chain Factor VIII (FVIII) connected to D'D3 domain of von Willebrand Factor (vWF). Its ingenious design allows efanesoctocog alfa to operate independently of endogenous vWF and results in an outstanding 3-4 times longer half-life compared to standard and extended half-life (EHL) FVIII products. The prolonged half-life ensures sustained high levels of factor activity, maintaining normal to near-normal ranges for the majority of the week, facilitating the convenience of once-weekly administration. Efanesoctocog alfa received regulatory approval in 2023 for application in both adults and children with inherited hemophilia A in the United States and Japan. Its sanctioned use encompasses both prophylaxis and 'on demand' treatment for bleeding episodes. The European Medicines Agency (EMA) is currently undertaking a comprehensive review of Altuviiio. TM This comprehensive review focuses on the immunological profile of efanesoctocog alfa, a highly sophisticated new class of EHL FVIII molecule. The integration of the vWF D'D3 domain, XTEN polypeptides, and potential regulatory T-cell epitopes within various segments of efanesoctocog alfa collectively serves as a mitigating factor against the development of a neutralizing T-cell-mediated immune response. We hypothesize that such distinctive attribute may significantly reduce the risk of neutralizing antibodies, particularly in previously untreated patients. The discussion extends beyond regulatory approval to encompass the preclinical and clinical development of efanesoctocog alfa, including considerations for laboratory monitoring. The review also highlights areas that warrant further investigation to deepen our understanding of this groundbreaking therapeutic agent.

Moving towards Normalization of haemostasis and health equity: Evolving treatment goals for haemophilia A

BACKGROUND

Treatment options for people with haemophilia are evolving at a rapid pace and a range of prophylactic treatment options using various technologies are currently available, each with their own distinct safety and efficacy profile.

TREATMENT GOALS

The access to replacement therapy and prophylaxis has driven a dramatic reduction in mortality and resultant increase in life expectancy. Beyond this, the abolition of bleeds and preservation of joint health represent the expected, but rarely attained, goals of haemophilia treatment and care. These outcomes also do not address the complexity of health-related quality of life impacted by haemophilia and its treatment.

CONCLUSION

Capitalizing on the major potential of therapeutic innovations, 'Normalization' of haemostasis, as a concept, should include the aspiration of enabling individuals to live as normal a life as possible, free from haemophilia-imposed limitations. To achieve this-being supported by the data reviewed in this manuscript-the concept of haemostatic and life Normalization needs to be explored and debated within the wider multidisciplinary teams and haemophilia community.

Changes in Quality of Life, Adherence, and Kinesiophobia in Patients with Hemophilia Treated with Extended Half-Life Treatment: Final Results of the LongHest Project

(1) Background: Hemophilia is a bleeding disorder characterized by hemarthrosis. Prophylaxis is the gold standard for bleeding prevention. Extended half-life (EHL) recombinant FVIII replacement products have shown to be associated with low bleeding rates. The aim was to evaluate the efficacy of EHL prophylaxis in improving perceived quality of life, adherence to treatment, and kinesiophobia in patients with hemophilia. (2) Methods: This was a prospective cohort study. Forty-six patients from different regions, who had started EHL FVIII concentrate prophylactic treatment, were evaluated at baseline and at 12-month follow-up. The study variables were as follows: perceived quality of life (36-Item Short Form Health Survey), adherence to treatment (Validated Hemophilia Regimen Treatment Adherence Scale-Prophylaxis), and kinesiophobia (Tampa Scale of Kinesiophobia). (3) Results: There were statistically significant differences in the domains Role-Physical (p < 0.001), Bodily Pain (p < 0.001), Role-Emotional (p < 0.001), Vitality (p = 0.04), and Social Functioning (p = 0.01) and the total scores, Physical Health (p < 0.001) and Mental Health (p < 0.001) on perceived quality of life. There were significant differences in the domains Skipping (p < 0.01), Communicating (p < 0.001), and the total score (p = 0.01) in terms of adherence. There were also significant differences in kinesiophobia (p = 0.02) after the study period. (4) Conclusions: EHL prophylaxis can improve the perceived quality of life of people with hemophilia. This prophylactic regimen, which requires fewer infusions, may improve adherence to treatment in adult patients with hemophilia over a 12-month period. The administration of extended half-life factor VIII concentrates can reduce kinesiophobia in adult patients with hemophilic arthropathy.

Nonsevere Hemophilia: The Need for a Renewed Focus and Improved Outcomes

People with nonsevere hemophilia (PWNSH) are phenotypically more diverse than those with severe hemophilia. Perceptions relating to a "nonsevere" phenotype have contributed to fewer research initiatives, fewer guidelines on optimal management, and a lack of standards for surveillance and clinical assessment for affected individuals. In many cases, episodes of abnormal bleeding could, if investigated, have led to earlier diagnosis. Furthermore, the major recent developments in therapy for hemophilia have largely focused on severe disease and, as a group, PWNSH have not been included in many key clinical trials. Benefiting people with severe disease, innovative replacement therapies have generally targeted factor levels that are above those present in a large proportion of PWNSH. Therapeutic advances can lead to improvement in phenotype for people with severe hemophilia over that currently experienced by many PWNSH. As a result, we are approaching a point where PWNSH may, in many countries, have a higher risk of bleeding and restriction in lifestyle than those with severe disease but with more limited therapeutic options. Given the multiple major advances in treatment for people with hemophilia, it is timely to review the aspects of nonsevere disease, to ensure equity in care and management for all individuals with this condition.

A post hoc analysis of PROTECT VIII kids assessing long-term efficacy and safety of damoctocog alfa pegol in adolescents with severe haemophilia A

INTRODUCTION

The safety and efficacy of the extended half-life factor VIII (FVIII) product damoctocog alfa pegol (BAY 94-9027, Jivi®) has been demonstrated in the PROTECT VIII Kids study (NCT01775618), where male previously-treated patients (PTPs) aged <12 years old with severe haemophilia A and ≥ 50 exposure days (EDs) were treated prophylactically. The PROTECT VIII Kids extension study assessed the long-term safety and efficacy of damoctocog alfa pegol in the same population.

AIM

To evaluate the long-term impact of damoctocog alfa pegol in a post hoc subgroup analysis of adolescent patients in the PROTECT VIII Kids study and its extension from 12th birthday onwards.

METHODS

The current analysis included PTPs aged ≥12 years old, who remained in the extension for ≥6 months following their 12th birthday. The observation period was defined as the time from 12th birthday to the end of the extension period; all data from this birthday were included whether in the main study or extension phase. The main efficacy variable was annualised bleeding rate (ABR) and the main safety variable was the frequency of inhibitor development.

RESULTS

This subgroup analysis comprised 25 patients. Median observation time after 12th birthday was 3.2 years. Median total/joint/spontaneous ABRs in the observation period were 1.7/0.7/0.3, respectively. Safety findings were consistent with those reported for the overall study population; no confirmed FVIII inhibitors or anti-drug antibodies were reported.

CONCLUSIONS

Damoctocog alfa pegol is efficacious with a favourable safety profile in adolescents with haemophilia A, supporting its long-term use in children and adolescents.

Bacterial Production of Recombinant Coagulation Factor VIII Domains

Factor VIII (F8) is a blood coagulation protein prearranged in six domains, and its deficiency causes hemophilia A. To fashion functional F8 therapeutics, development of a recombinant F8 (rF8) domain is essential not only for F8 substitution, but also to decipher the F8-related mechanisms. In this study, we generated Glutathione S-transferase (GST)-conjugated recombinant A2 and A3 domains of F8 using Escherichia coli. The high growth rate and economically advantageous protein production system in terms of inexpensive reagents and materials in E. coli cells facilitated the completion of entire process from protein expression to purification in 3-4 days with low production cost. Subsequent assessment of these purified proteins using enzyme-linked immunosorbent assay (ELISA) and antibodies against F8 revealed enhanced detection of rF8-A2 or rF8-A3 in a concentration dependent manner, indicating the presence of the antibody-binding epitopes in these proteins. Furthermore, these proteins are suitable for generating novel antibodies against the F8 domain and F8 domain-capturing affinity columns by enabling their conjugation to GST-capturing beads. Additionally, the recombinant F8 domains produced herein can be used for various studies, which include investigating the explicit roles of the F8 domain in the coagulation process, with domain-specific binding partners, and antibodies.

Clinical Predictors and Prediction Models for rFVIII-Fc Half Life in Real-World People with Severe Hemophilia A

The half life of recombinant factor VIII-Fc (rFVIII-Fc) for people with hemophilia A (PwHA) varies greatly. Understanding the factors influencing the variation and assessment of rFVIII-Fc half life is important for personalized treatment. Eighty-five severe-type PwHA with rFVIII-Fc treatment receiving an evaluation of half life by the Web-Accessible Population Pharmacokinetic (PK) Service—Hemophilia during 2019–2021 were retrospectively enrolled. The 50-patient PK profiles before 2021 were used for analysis and developing prediction models of half life, and the 35-patient PK profiles in 2021 were used for external validation. The patients in the development cohort were aged 8–64, with a median rFVIII-Fc half life of 20.75 h (range, 8.25–41.5 h). By multivariate linear regression analysis, we found two, four, and five predictors of rFVIII-Fc half life for the blood groups non-O, O patients, and overall patients, respectively, including VWF:Ag, BMI, VWF:activity/VWF:Ag ratio, body weight, O blood group, inhibitor history, HCV infection, and hematocrit. The three prediction equations of rFVIII-Fc half life (T) were respectively developed as T for non-O group patients = −0.81 + 0.63 × (BMI, kg/m2) + 6.07 × (baseline VWF:Ag, IU/mL), T for O group patients = −0.68 + 13.30 × (baseline VWF:Ag, IU/mL) + 0.27 × (BW, kg) − 1.17 × (BMI, kg/m2) + 16.02 × (VWF:activity/VWF:Ag ratio), and T for overall patients = −1.76 + 7.24 × (baseline VWF:Ag, IU/mL) − 3.84 × (Inhibitor history) + 2.99 × (HCV infection) − 2.83 × (O blood group) + 0.30 × (Hct, %), which explained 51.97%, 75.17%, and 66.38% of the half life variability, respectively. For external validation, there was a significant correlation between the predicted and observed half lives in the validation cohort. The median half life deviation was +1.53 h, +1.28 h, and +1.79 h for the equations of non-O group, O group, and overall group patients, respectively. In total, eight predictors influencing rFVIII-Fc half life were identified. Prediction equations of rFVIII-Fc half life were developed for the non-O and O blood groups and overall PwHA with a good degree of external validation. The equations could be applied to patients aged 8–64 without the need for PK blood sampling and clinically valuable for personalized therapy.

Real-world bleeding outcomes and product utilization in people with severe-type hemophilia A before and after switching to extended half-life rFVIIIFc prophylaxis therapy

BACKGROUND

Recombinant factor VIII-Fc (rFVIIIFc) became available in Taiwan in 2018. Before this date, no people with hemophilia A (PwHA) were enrolled in a clinical trial of rFVIIIFc. We investigated changes in bleeding outcomes and product utilization in PwHA switching from rFVIII to rFVIIIFc.

METHODS

Data were collected for Taiwanese PwHA (severe-type) who switched from rFVIII to rFVIIIFc, including annualized bleeding rate (ABR) and weekly dose consumption 12 months pre-switch and > 6 months post-switch.

RESULTS

The 51 patients were divided into 3 groups according to their pre-switch treatment: on-demand treatment, intermittent periodic prophylaxis, and regular prophylaxis. In every group, the post-switch median ABR was significantly reduced, with no significant differences between groups. Meanwhile, the post-switch median weekly dose of each group was significantly increased. In 32 patients on pre-switch prophylaxis, switching brought a further reduction in median ABR, associated with a significant increase in median weekly dose. No adverse effects or novel inhibitor development were seen.

CONCLUSION

This is the first report from Asia on real-world experience of rFVIIIFc, showing that switching to rFVIIIFc prophylaxis led to further reduction in ABR and increase in weekly dose for all patient groups, even those on pre-switch rFVIII prophylaxis.

Cost-effectiveness of recombinant factor VIII Fc versus emicizumab for prophylaxis in adults and adolescents with haemophilia A without inhibitors in the UK

INTRODUCTION

The economic and clinical burden of haemophilia A is high. Primary prophylaxis with factor VIII replacement therapy is the recognised standard of care, but the emergence of non-factor therapies, such as emicizumab, is extending treatment options for people with haemophilia A.

AIM

There are currently no direct comparisons of efficacy or cost between recombinant factor FVIII Fc-fusion protein efmoroctocog alfa (a recombinant factor FVIII Fc-fusion protein referred to herein as rFVIIIFc) and emicizumab; therefore, a cost-effectiveness model was developed to compare prophylactic treatment with rFVIIIFc versus emicizumab in patients with haemophilia A without inhibitors in the UK.

METHODS

The cost-effectiveness model was based on a matching-adjusted indirect comparison and included male patients, aged ≥12 years, with haemophilia A without inhibitors. The model was designed as a Markov process with a flexible lifelong time horizon, and cost-effectiveness was presented as an incremental cost-effectiveness ratio. Base-case analysis and sensitivity analyses (including scenario analyses, one-way deterministic sensitivity analysis [DSA] and probability sensitivity analysis [PSA]) were performed using the following treatment strategies: individualised prophylaxis with rFVIIIFc and prophylaxis with emicizumab administered once weekly (scenario analyses used regimens of once every 2 weeks or once every 4 weeks).

RESULTS

Base-case analysis, DSA and PSA indicated that, compared with emicizumab administered once weekly, rFVIIIFc individualised prophylaxis was the dominant treatment strategy, with lower costs, a greater number of quality-adjusted life years, and a lower number of bleeds.

CONCLUSIONS

rFVIIIFc has proven efficacy and is cost-effective compared with emicizumab, providing clinicians with a viable treatment option to improve the health outcomes for adults and adolescents with haemophilia A in the UK.

The More Recent History of Hemophilia Treatment

The availability first in the 1970s of plasma-derived and then in the 1990s of recombinant clotting factor concentrates represented a milestone in hemophilia care, enabling not only treatment of episodic bleeding events but also implementation of prophylactic regimens. The treatment of hemophilia has recently reached new landmarks. The traditional clotting factor replacement therapy for hemophilia has been substituted over the last 10 years by novel treatments such as bioengineered factor VIII and IX molecules with extended half-life and non-factor treatments including the bispecific antibody emicizumab. This narrative review is dedicated to these newer therapies, which are contributing significantly to improving the long-term management of prophylaxis in hemophilia patients. Another section is focused on the current state of gene therapy, which is a promising definitive cure for severe hemophilia A and B.

Expert opinion on current and future prophylaxis therapies aimed at improving protection for people with hemophilia A

The next frontier in hemophilia A management has arrived. However, questions remain regarding the broader applicability of new and emerging hemophilia A therapies, such as the long-term safety and efficacy of non-factor therapies and optimal regimens for individual patients. With an ever-evolving clinical landscape, it is imperative for physicians to understand how available and future hemophilia A therapies could potentially be integrated into real-life clinical practice to improve patient outcomes. Against this background, nine hemophilia experts from Central European countries participated in a pre-advisory board meeting survey. The survey comprised 11 multiple-choice questions about current treatment practices and future factor and non-factor replacement therapies. The survey questions were developed to reflect current unmet needs in hemophilia management reflected in the literature. The experts also took part in a follow-up advisory board meeting to discuss the most important unmet needs for hemophilia management as well as the pre-meeting survey results. All experts highlighted the challenge of maintaining optimal trough levels with prophylaxis as their most pressing concern. Targeting trough levels of ≥30-50 IU/L or even higher to achieve less bleeding was highlighted as their preferred strategy. However, the experts had an equal opinion on how this could be achieved (i.e., more efficacious non-factor therapies or factor therapy offering broader personalization possibilities such as targeting trough levels to individual pharmacokinetic data). In summary, our study favors personalized prophylaxis to individual pharmacokinetic data rather than a "one-size-fits-all" approach to hemophilia A management to maintain optimal trough levels for individual patients.

Hemophilia A Gene Therapy: Current and Next-Generation Approaches

INTRODUCTION

: Hemophilia comprises a group of X-linked hemorrhagic disorders that result from a deficiency of coagulation factors. The disorder affects mainly males and leads to chronic pain, joint deformity, reduced mobility, and increased mortality. Current therapies require frequent administration of replacement clotting factors, but the emergence of alloantibodies (inhibitors) diminishes their efficacy. New therapies are being developed to produce the deficient clotting factors and prevent the emergence of inhibitors.

AREAS COVERED

: This article provides an update on the characteristics and disease pathophysiology of hemophilia A, as well as current treatments, with a special focus on ongoing clinical trials related to gene replacement therapies.

EXPERT OPINION

: Gene replacement therapies provide safe, durable, and stable transgene expression while avoiding the challenges of clotting factor replacement therapies in patients with hemophilia. Improving the specificity of the viral construct and decreasing the therapeutic dose are critical toward minimizing cellular stress, induction of the unfolded protein response, and the resulting loss of protein production in liver cells. Next-generation gene therapies incorporating chimeric DNA sequences in the transgene can increase clotting factor synthesis and secretion, and advance the efficacy, safety, and durability of gene replacement therapy for hemophilia A as well as other blood clotting disorders.

Recombinant factor VIII Fc for the treatment of haemophilia A

Prophylaxis with factor VIII (FVIII) is the current therapeutic approach for people with haemophilia A. However, standard half-life (SHL) FVIII products must be injected frequently, imposing a substantial burden on the individual and making it difficult to tailor therapy according to patient need and lifestyle, which could impact adherence. Recombinant FVIII Fc fusion protein (rFVIIIFc; Elocta® , Sobi; Eloctate® , Sanofi) is a recombinant fusion protein that undergoes slower clearance from the body than SHL FVIII products. This pharmacokinetic property of rFVIIIFc allows prophylactic administration every 3-5 days, or once weekly in selected patients, with doses adjusted to patient needs and clinical outcomes. Higher FVIII levels can be achieved maintaining dosing frequency similar to that usually applied with SHL FVIII. This review provides a summary of recent data from the A-LONG, Kids A-LONG, ASPIRE and PUPs A-LONG studies and recently published real-world experience relevant to rFVIIIFc use in individualised regimens. The review also introduces ongoing studies of rFVIIIFc, including its use for induction of immune tolerance, and discusses some aspects to consider when switching patients to rFVIIIFc and managing ongoing treatment. In summary, rFVIIIFc is suitable for individualised prophylaxis regimens that can be tailored according to patient clinical needs and lifestyle.