Clinical use of recombinant factor VIII Fc and recombinant factor IX Fc in patients with haemophilia A and B

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.

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.

Strategies for overcoming protein and peptide instability in biodegradable drug delivery systems

The global pharmaceutical market has recently shifted its focus from small molecule drugs to peptide, protein, and nucleic acid drugs, which now comprise a majority of the top-selling pharmaceutical products on the market. Although these biologics often offer improved drug specificity, new mechanisms of action, and/or enhanced efficacy, they also present new challenges, including an increased potential for degradation and a need for frequent administration via more invasive administration routes, which can limit patient access, patient adherence, and ultimately the clinical impact of these drugs. Controlled-release systems have the potential to mitigate these challenges by offering superior control over in vivo drug levels, localizing these drugs to tissues of interest (e.g., tumors), and reducing administration frequency. Unfortunately, adapting controlled-release devices to release biologics has proven difficult due to the poor stability of biologics. In this review, we summarize the current state of controlled-release peptides and proteins, discuss existing techniques used to stabilize these drugs through encapsulation, storage, and in vivo release, and provide perspective on the most promising opportunities for the clinical translation of controlled-release peptides and proteins.

Post hoc longitudinal assessment of the efficacy and safety of recombinant factor IX Fc fusion protein in hemophilia B

Long-term efficacy and safety of the extended half-life recombinant factor IX Fc fusion protein (rFIXFc) has been established among previously treated patients with severe hemophilia B in 2 phase 3 trials (B-LONG [#NCT01027364] and Kids B-LONG [#NCT01440946]) and a long-term extension study (B-YOND [#NCT01425723]). In this study, we report post hoc analyses of pooled longitudinal data for up to 6.5 years for rFIXFc prophylaxis. In the B-LONG study, subjects ≥12 years received weekly dose-adjusted prophylaxis (WP; starting dose, 50 IU/kg), individualized interval-adjusted prophylaxis (IP; initially, 100 IU/kg every 10 days), or on-demand dosing. In the Kids B-LONG study, subjects <12 years received 50 to 60 IU/kg every 7 days, adjusted as needed. In the B-YOND study, subjects received WP (20-100 IU/kg every 7 days), IP (100 IU/kg every 8-16 days), modified prophylaxis, or on-demand dosing; switching between treatment groups was permitted. A total of 123 subjects from B-LONG and 30 from Kids B-LONG study were included, of whom 93 and 27, respectively, enrolled in the B-YOND study. The median cumulative duration of treatment was 3.63 years (range, 0.003-6.48 years) in B-LONG/B-YOND and 2.88 years (range, 0.30-4.80 years) in Kids B-LONG/B-YOND group. Annualized bleed rates (ABRs) remained low, annualized factor consumption remained stable, and adherence remained high throughout treatment. Low ABRs were also maintained in subjects with dosing intervals ≥14 days or with target joints at baseline. Complete resolution of evaluable target joints and no recurrence in 90.2% of baseline target joints during follow-up were observed. rFIXFc prophylaxis was associated with sustained clinical benefits, including long-term bleed prevention and target joint resolution, for severe hemophilia B.

Clinical outcome and incidence of inhibitor development in severe hemophilia patients receiving low-dose prophylaxis: a 3-year follow-up study in Senegal, West Africa

INTRODUCTION

In Africa, where access to diagnosis and treatment of hemophilia is the lowest in the world, prophylaxis is rarely used in preference to on-demand treatment. There are limited data of prophylaxis treatment from sub-Saharan Africa. The aim of this study was to evaluate clinical outcomes and inhibitor development in people with hemophilia receiving low-dose prophylaxis (LDP) in a sub-Saharan African setting.

METHODS

We conducted a three-year prospective study. A once or twice weekly prophylaxis regimen of 25 IU/kg of rFVIIIFc or 30 IU/kg of rFIXFc was given to Hemophilia A and B, respectively. We evaluated clinical outcomes and inhibitors occurrence, determined by screening and titration using the Nijmegen technique.

RESULTS

A total of 15 patients were included in the LDP regimen. The mean age was 6.3 years (1.5 - 10). A significant reduction was noted in the annualized bleeding rate, from 7.53 to 1.33 (p = 0.0001); the annualized joint bleeding rate passed from 3.6 to 1.4 (p = 0.001) and the proportion of severe bleeding, from 86.1% to 16.7% (p = 0.0001). The Hemophilia Joint Health Score (HJHS) moved from 9.6 to 3.4 (p = 0.0001) and the Functional Independence Score in Hemophilia (FISH) improved from 25.8 to 30.9 (p = 0.0001). School absenteeism decreased from 7.33% to 2.59%. Adherence to prophylaxis was 89.5% versus 60%. Consumption was 580 IU/kg/year versus 1254.6 IU/kg/year before and after prophylaxis, respectively. Incidence of inhibitors was 23% (3 /13 HA).

CONCLUSION

The LDP in Hemophilia improves the clinical outcome without a surplus risk of inhibitor development. Using extended half-life clotting factor concentrates (CFCs) is better for prophylaxis in resource-limited countries, as they allow better compliance in treatment.

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.

rFVIII-Fc in severe haemophilia A: The incentive switch in case of high risk of joint bleedings

BACKGROUND

Efmoroctocog alfa, the first recombinant factor VIII fusion protein with extended half-life (rFVIII-Fc), has been hypothesized to lower FVIII consumption in patients with severe Haemophilia A (pwSHA), without reducing clinical efficacy. What about real life?

METHOD

MOTHIF-II was a noninterventional, multicentre, before/after study, via the collection of retrospective data from July 2015 to June 2016 (called T1), and from July 2017 to June 2018 (called T2), in 7 French haemophilia treatment centres. We examined the prescriptions and dispensations of factor VIII and the Annual Bleeding Rate (ABR), in pwSHA without current inhibitors on prophylaxis, before and after the introduction of rFVIII-Fc. The data gathered from the BERHLINGO research database and from the French Healthcare claims database with a determinist pairing process based on the national unique identification number.

RESULTS

A total of 156 pwSHA were included in the prescription cohort and 83 in the ABR cohort. For switched patients, the mean amounts of prescribed FVIII were significantly higher during T1 compared to T2 (4333 (2052) vs. 3921 (2029) IU/kg/year/patient, p: 0.028); a significant decrease in their ABR was also observed between T1 and T2 (6.3 (6.0) vs. 4.4 (5.4), p: 0.047). These patients had a more severe bleeding profile centred on haemarthrosis.

CONCLUSION

The results are related to those of the pivotal clinical trials for the reduction in FVIII consumption following the switch to rFVIII-Fc, with a significant improvement in the haemorrhagic phenotype for pwSHA.

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

INTRODUCTION

Majority of haemophilia A patients in our comprehensive care centre have switched from standard half-life (SHL) to extended half-life (EHL) FVIII products in a short time.

AIM

We compared the clinical and laboratory outcomes between SHL and EHL FVIII prophylaxis in product switchers.

METHODS

This is a retrospective inception cohort of all adult haemophilia A patients switched to EHL (rFVIIIFc or rFVIII-PEG) prophylaxis in our centre. Dosing, product utilization, annualized bleed rates (ABR), treatment regimen and pharmacokinetics by Web Accessible Population Pharmacokinetic Service (WAPPS)-Hemo were compared between SHL and EHL.

RESULTS

We included 38 patients, whose median age was 38 years (range 17-75). Median FVIII dose was 23 IU/kg for SHL versus 25 IU/kg for EHL. After switching, weekly infusions decreased by 29% from median 2.8 (every 2.5 days) to 2.0 (every 3.5 days) (P = <.001) and factor consumption for prophylaxis by 17% from 60 to 50 IU/kg/week (P = <.001). Weekly infusions decreased in 71% and FVIII utilization in 55% of patients. ABR remained low (1.0 for SHL and .5 for EHL, respectively). In pharmacokinetics, the half-life of FVIII increased from median 13 to 21 h after switching. Times above .01 and .03 IU/ml improved from 85 to 131 h and from 65 to 106 h. Half-lives of the SHL products and von Willebrand factor levels predicted half-lives with the EHL products.

CONCLUSIONS

Our cohort study confirms the successful experience of switching to EHL FVIII products, with decreased infusion frequency, factor consumption and excellent clinical efficacy.

LongHest project: A prospective, observational study of extended half-life treatment in the musculoskeletal health of patients with severe haemophilia A

Background

Prophylactic treatment is the gold standard in the treatment of patients with haemophilia. Prophylaxis with extended half‐life (EHL) treatment has shown long‐term safety and efficacy in patients with haemophilia.

Aim

To evaluate the efficacy of prophylaxis with EHL treatment in the frequency of haemarthrosis and musculoskeletal health in adult patients with severe haemophilia A.

Methods

Prospective cohort study. Forty‐six patients with severe haemophilia A were recruited. The frequency of haemarthrosis (self‐reports), joint condition (Haemophilia Joint Health Score), pain intensity (visual analogue scale), range of motion (goniometry), and strength (dynamometry) and muscle activation (surface electromyography) were evaluated. Three assessments were carried out: at baseline (T0), at 6 months (T1) and at 12 months following treatment (T2).

Results

There were significant changes in the within‐subject effect in the frequency of haemarthrosis in elbow (F(1.05;96.20) = 3.95; P < .001) and knee (F(1.73;157.99) = 9.96; P < .001). Significant within‐subject effect in elbow pain intensity (F(2;182) = 63.51; P < .001) was found. The mean values of the frequency haemarthrosis in elbow (from .66±1.01 to .04±.20) and knees (from .55±.68 to .33±.53) decrease after the period study. The intensity of elbow pain and (from 3.08±1.69 to 2.67±1.73), decrease after the 12‐month follow‐up period.

Conclusions

Prophylaxis with extended half‐life treatment reduces the frequency of haemarthrosis in elbow and knee in adult patients with haemophilia. EHL treatment reduces the intensity of elbow pain in patients with haemophilic arthropathy.

Clinical application of extended half-life factor VIII in children with severe haemophilia A

INTRODUCTION

Only few studies have presented results from real-world clinical use of Extended Half-Life (EHL) products in children with haemophilia (CWH).

AIM

To retrospectively examine real-life experience with EHL factor VIII products use in CWH A, comparing with clinical experience from standard half-life products (SHL).

METHODS

A retrospective review of medical records of CWH A who have been prescribed EHL factor concentrates was conducted. All before/after comparisons were performed with the Wilcoxon matched-pairs signed-ranks test.

RESULTS

Twenty-three children with severe haemophilia A were enrolled in the study (3-6 years old: n = 4, 7-12 years old: n = 7 and 13-18 years old: n = 12). Median length of time that patients were treated with EHL products was 78 weeks. Median dosing interval was significantly lengthened from 2.3 to 3.5 days after switching from SHL to EHL concentrates. Mean trough FVIII levels were significantly increased from 2.3% to 4.1% after treatment with EHL products. Also, CWH A had a reduction of mean annual bleeding rate (ABR) and mean annual joint bleeding rate (AJBR) from 1 and .8 to .3 and .2, respectively, following treatment with EHL concentrates (ABR: p = .02, AJBR: p = .05). However, after switching to factor EHL, actual FVIII consumption, including bleeds, was significantly increased from 94 IU/kg/week to 118 IU/kg/week in CWH A. There was no inhibitor development.

CONCLUSION

This study demonstrates the successful transition of 23 CWH A from SHL to EHL factor concentrates.

A survey of physicians' treatment switching practice in people on long-term prophylaxis for hemophilia in five European countries

OBJECTIVE

Recombinant factor VIII and factor IX Fc fusion proteins (rFVIIIFc and rFIXFc) were developed with an extended half-life (EHL) to improve the management of people with hemophilia A (PwHA) and B (PwHB), respectively.

METHODS

This survey gathered physician-reported treatment decisions and physician views on outcomes in PwHA or PwHB who switched to rFVIIIFc or rFIXFc in the 12 months prior to study completion.

RESULTS

Physicians (N = 37) considered bleeds, pharmacokinetic parameters, joint health and adherence the most important factors to assess both in routine care and when deciding to switch to an EHL therapy. In the 12 months prior to study completion, 37 physicians switched 113 PwHA to rFVIIIFc and 25 physicians switched 36 PwHB to rFIXFc. Most PwH (>90%) had moderate or severe hemophilia and many (>60%) switched within 6 months of the survey. The main reason for switching PwHA to rFVIIIFc was to allow fewer injections (49%), while the main reason for switching PwHB to rFIXFc was the product becoming available for use (36%). Overall, 96% of PwHA and 89% of PwHB who were switched remained on these EHL products at the time of survey. Mean total weekly dose, injection frequency and annualized bleeding rate were reported to have reduced following switching.

CONCLUSION

This survey provides valuable insight into reasons for, and challenges to, the use of EHL products in clinical practice. Physicians perceived that switching to treatment with rFVIIIFc or rFIXFc can improve quality of life, treatment burden, disease control and adherence.

Efmoroctocog Alfa: A Review in Haemophilia A

Efmoroctocog alfa (Elocta®, Eloctate®, Eloctate™), an extended half-life (EHL) recombinant factor VIII (rFVIII)-Fc fusion protein, is approved for the treatment and prophylaxis of bleeding in patients with haemophilia A. The efficacy of efmoroctocog alfa in the prevention and treatment of bleeding in previously treated patients (PTPs) and previously untreated patients (PUPs) with severe haemophilia A has been demonstrated in phase III studies; this includes its use in the perioperative setting (in PTPs). Furthermore, the effectiveness of efmoroctocog alfa in clinical practice has been confirmed in numerous real-world studies; compared with conventional, standard half-life (SHL) FVIII products, prophylaxis with this EHL FVIII product achieved similar or reduced bleeding rates with fewer injections. Efmoroctocog alfa was generally well tolerated; inhibitors occurred in approximately one-third of PUPs in a phase III study. Efmoroctocog alfa is an established and effective EHL FVIII replacement therapy for the management of haemophilia A. Compared with SHL FVIII products, EHL FVIII products such as efmoroctocog alfa have the potential to optimise prophylactic outcomes by decreasing the burden of treatment or increasing the level of bleed protection.

Current therapeutic approaches in the management of hemophilia-a consensus view by the Romanian Society of Hematology

Hemophilia A (HA) and hemophilia B (HB) are rare disorders, being caused by the total lack or under-expression of two factors from the coagulation cascade coded by genes of the X chromosome. Thus, in hemophilic patients, the blood does not clot properly. This results in spontaneous bleeding episodes after an injury or surgical intervention. A patient-centered regimen is considered optimal. Age, pharmacokinetics, bleeding phenotype, joint status, adherence, physical activity, personal goals are all factors that should be considered when individualizing therapy. In the past 10 years, many innovations in the diagnostic and treatment options were presented as being either approved or in development, thus helping clinicians to improve the standard-of-care for patients with hemophilia. Recombinant factors still remain the standard of care in hemophilia, however they pose a challenge to treatment adherence because they have short half-life, which where the extended half-life (EHL) factors come with the solution, increasing the half-life to 96 hours. Gene therapies have a promising future with proven beneficial effects in clinical trials. We present and critically analyze in the current manuscript the pros and cons of all the major discoveries in the diagnosis and treatment of HA and HB, as well as identify key areas of hemophilia research where improvements are needed.

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.

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.

Real-world outcomes with recombinant factor IX Fc fusion protein (rFIXFc) prophylaxis: Longitudinal follow-up in a national adult cohort

INTRODUCTION

In 2017, all people with severe haemophilia B (PWSHB) in Ireland switched from standard half-life (SHL) recombinant FIX (rFIX) to rFIX Fc fusion protein (rFIXFc) prophylaxis.

AIMS

To evaluate prophylaxis regimens, bleeding rates and factor usage for two years of rFIXFc prophylaxis in a real-world setting.

METHODS

Data collected retrospectively from electronic diaries and medical records of PWSHB for a two-year period on rFIXFc prophylaxis were compared with paired baseline data on SHL rFIX treatment.

RESULTS

28 PWSHB (≥18 years) were enrolled, and at switchover 79% were receiving prophylaxis and 21% episodic treatment with SHL rFIX. At 24 months following switchover, all remained on rFIXFc prophylaxis with reduced infusion frequency; median dose per infusion once weekly (55 IU/kg, 20/28), every 10 days (63 IU/kg, 2/28) or every 14 days (98 IU/kg, 6/28). Median annualised bleed rate improved significantly on rFIXFc prophylaxis (2.0 versus 3.3 on SHL FIX) (p = 0.01). Median FIX trough level with once-weekly infusions was 0.09 IU/ml (0.06-0.14 IU/ml). Management of bleeding episodes was similar with rFIXFc and SHL rFIX; one infusion was sufficient to treat 74% and 77% of bleeds, respectively, with similar total median treatment per bleeding episode. Factor consumption reduced by 28% with rFIXFc prophylaxis (57 IU/kg/week, range 40-86 IU/kg/week) compared with SHL rFIX (79 IU/kg/week, range 44-210 IU/kg/week) (p = 0.002).

CONCLUSION

This study provides important insights into real-world experience of switching to rFIXFc prophylaxis in an adult population, demonstrating high rates of prophylaxis, with reduced infusion frequency, bleeding and FIX consumption.

Clinical, humanistic, and economic burden of severe hemophilia B in the United States: Results from the CHESS US and CHESS US+ population surveys

BACKGROUND

Hemophilia B is a rare congenital bleeding disorder that has a significant negative impact on patients' functionality and health-related quality of life. The standard of care for severe hemophilia B in the United States is prophylactic factor IX replacement therapy, which incurs substantial costs for this lifelong condition. Accurate estimates of the burden of hemophilia B are important for population health management and policy decisions, but have only recently accounted for current management strategies. The 'Cost of Severe Hemophilia across the US: a Socioeconomic Survey' (CHESS US) is a cross-sectional database of medical record abstractions and physician-reported information, completed by hematologists and care providers. CHESS US+ is a complementary database of completed questionnaires from patients with hemophilia. Together, CHESS US and CHESS US+ provide contemporary, comprehensive information on the burden of severe hemophilia from the provider and patient perspectives. We used the CHESS US and CHESS US+ data to analyze the clinical, humanistic, and economic burden of hemophilia B for patients treated with factor IX prophylaxis between 2017 and 2019 in the US.

RESULTS

We conducted analysis to assess clinical burden and direct medical costs from 44 patient records in CHESS US, and of direct non-medical costs, indirect costs, and humanistic burden (using the EQ-5D-5L) from 57 patients in CHESS US+. The mean annual bleed rate was 1.73 (standard deviation, 1.39); approximately 9% of patients experienced a bleed-related hospitalization during the 12-month study period. Nearly all patients (85%) reported chronic pain, and the mean EQ-5D-5L utility value was 0.76 (0.24). The mean annual direct medical cost was $614,886, driven by factor IX treatment (mean annual cost, $611,971). Subgroup analyses showed mean annual costs of $397,491 and $788,491 for standard and extended half-life factor IX treatment, respectively. The mean annual non-medical direct costs and indirect costs of hemophilia B were $2,371 and $6,931.

CONCLUSIONS

This analysis of patient records and patient-reported outcomes from CHESS US and CHESS US+ provides updated information on the considerable clinical, humanistic, and economic burden of hemophilia B in the US. Substantial unmet needs remain to improve patient care with sustainable population health strategies.

Decreased Bleeding Rates in Patients with Hemophilia A Switching from Standard-Half-Life FVIII to BAY 94-9027 Prophylaxis

BAY 94-9027 (damoctocog alfa pegol, Jivi) is an extended-half-life recombinant factor VIII (rFVIII) shown to be well-tolerated and efficacious in bleeding prevention in previously treated patients with severe hemophilia A. During the PROTECT VIII study, prophylaxis patients received BAY 94-9027 at intervals determined based on their bleeding phenotype, observed during a 10-week run-in treatment period with twice-weekly dosing. Those with ≤ 1 spontaneous joint or muscle bleed were randomized to either 45 to 60 IU/kg every 5 days or 60 IU/kg every 7 days; patients could increase dosing frequency to every 5 days or twice weekly in the case of bleeds. Those enrolled after the randomization arms were full, and those with ≥ 2 bleeds in the run-in period, received 30 to 40 IU/kg twice weekly. Patients completing the main study could receive open-label BAY 94-9027 in the extension phase. Dosing regimen, total, and joint annualized bleeding rates were analyzed over three periods: prestudy, main study, and extension. A total of 80 patients who were on prophylaxis treatment prior to and during the study and had prior bleed data available were evaluated in this post hoc analysis of PROTECT VIII. Most patients (> 80%) required fewer infusions with BAY 94-9027 prophylaxis versus their previous standard-half-life (SHL) rFVIII product. Lower bleeding and joint bleeding rates were observed over time from the prestudy to the extension study period in all treatment regimens. Compared with SHL FVIII, BAY 94-9027 prophylaxis allows patients to reduce infusion frequency with maintained or improved protection from bleeds.

Pharmacodynamics of eftrenonacog-alfa (rFIX-Fc) in severe hemophilia B patients: A real-life study

Eftrenonacog-alfa is a recombinant factor IX-Fc fusion protein increasingly prescribed in hemophilia B patients. We aimed to assess its pharmacodynamics (PD) in real-life setting via FIX activity measurement and thrombin generation assay (TGA). Sixty samples from 15 severe hemophilia B treated patients were collected at different time points. FIX activity was measured using product-specific one-stage clotting assay (reference method) and two chromogenic assays (CSA) (Biophen FIX and Rox FIX). TGA was triggered with 1 pM tissue factor. Five parameters were analyzed: lag time (LT), time to peak (TTP), peak height (PH), endogenous thrombin potential (ETP), and velocity. PD models were built to characterize their relationships with FIX activity, using mixed effects models. Mean trough FIX level was estimated at 4.64 (±1.50) IU/dl with a recovery at 0.78 (±0.16) IU/dl per 1 IU/kg injected dose. FIX activity ranged between 1 and 86 IU/dl with 21.5 IU/dl median value. Biophen FIX and Rox FIX allowed reliable measurements except in samples with FIX <20 IU/dl in which values were underestimated (delta >30%). PD models revealed that velocity was the most sensitive TGA parameter to FIX activity followed by PH, ETP, TTP and finally LT. Following FIX activity peak after eftrenonacog-alfa injection, velocity decreased first, followed by PH then ETP. Both CSA failed to accurately measure FIX in severe hemophilia B patients receiving eftrenonacog-alfa throughout the measuring range. TGA could be an additional valuable tool to evaluate hemostasis balance in treated patients.

Real-world outcomes associated with standard half-life and extended half-life factor replacement products for treatment of haemophilia A and B

: Standard-of-care treatment for haemophilia A or B is to maintain adequate coagulation factor levels through clotting factor administration. The current study aimed to evaluate annualised bleeding rates (ABR) and treatment adherence for haemophilia A or B patients receiving standard half-life (SHL) vs. extended half-life (EHL) factor replacement products. We analysed data from the Adelphi Disease-Specific Programmes, a health record-based survey of United States and European haematologists. Analysis included 651 males with moderate-to-severe haemophilia A or B (the United States, n = 132; Europe, n = 519). The haemophilia A analysis included 501 patients (SHL, n = 435; EHL, n = 66). In the combined United States/European population, mean (SD) ABR was 1.7 (1.69) for the SHL group and 1.8 (2.00) for the EHL group. A total of 72% of patients receiving SHL factor VIII and 75% of patients receiving EHL factor VIII in the combined population were fully adherent (no doses missed of the last 10 doses), as reported by physicians. The haemophilia B analysis included 150 patients (SHL, n = 114; EHL, n = 36). The mean (SD) ABR in the combined population was 2.1 (2.16) for patients receiving SHL factor IX (FIX) and 1.4 (1.48) for patients receiving EHL FIX. The percentage of fully adherent patients (physician-reported) was similar in both treatment groups (SHL FIX, 68%; EHL FIX, 73%). In this preliminary real-world survey in a relatively small sample of patients, measures of ABR and adherence between SHL and EHL products were evaluated. Additional real-world research on prescribing patterns, SHL vs. EHL effectiveness, and adherence is warranted.

Real-world data demonstrate improved bleed control and extended dosing intervals for patients with haemophilia B after switching to recombinant factor IX Fc fusion protein (rFIXFc) for up to 5 years

Introduction

In clinical trials, recombinant factor IX fusion protein (rFIXFc) has demonstrated safety, efficacy and prolonged activity with extended dosing intervals for treatment of haemophilia B.

Aim

To assess the real‐world clinical utility of rFIXFc in a variable patient population and routine clinical practice.

Methods

A multicentre, retrospective chart review was conducted of patients with haemophilia B who had received rFIXFc prophylaxis or on‐demand treatment for ≥6 months across six sites in the United States.

Results

Sixty‐four eligible patients were identified who had a median (range) duration on rFIXFc of 2.7 (0.5‐5.0) years. Of 32 patients on rFIXFc prophylaxis who switched from prophylaxis with another factor treatment (ie pre‐rFIXFc) and had a known pre‐rFIXFc dosing interval, the initial dosing interval was lengthened for 26 (81%) patients and maintained for the remaining 6 (19%) patients. Most (n = 48 [91%]) patients who received rFIXFc prophylaxis from the beginning to the end of the chart review period (n = 53) maintained or lengthened the dosing interval from first through last dose of rFIXFc. For patients receiving rFIXFc prophylaxis, there was an approximate 50% reduction in weekly factor consumption compared with pre‐rFIXFc prophylaxis. Overall annualized bleed rates, annualized spontaneous bleed rates and annualized joint bleed rates decreased after switching to rFIXFc prophylaxis (n = 24 with bleed data). Compliance to recommended treatment improved or remained stable in most patients with available data (30/31).

Conclusion

Recombinant factor IX fusion protein prophylaxis improved bleed control, reduced overall consumption, reduced frequency of infusion and improved compliance for patients with haemophilia B in a real‐world setting.

Emerging benefits of Fc fusion technology in the context of recombinant factor VIII replacement therapy

Although the primary reason for recombinant factor VIII Fc fusion protein (rFVIIIFc) development was to reduce treatment burden associated with routine prophylaxis, new evidence suggests additional benefits of Fc fusion technology in the treatment of people with haemophilia A. Preclinical research has been utilized to characterize the potential immunomodulatory properties of rFVIIIFc, including an ability to reduce inflammation and induce tolerance to factor VIII. This has since been expanded into clinical research in immune tolerance induction (ITI) with rFVIIIFc, results of which suggest the potential for rapid tolerization in first‐time ITI patients and therapeutic benefit in patients undergoing rescue ITI. The potential for improved joint health through the anti‐inflammatory properties of rFVIIIFc has also been suggested. In addition, a new avenue of research into the role of rFVIIIFc in promoting bone health in patients with haemophilia A, potentially through reduced osteoclast formation, has yielded encouraging results that support further study. This review summarizes the existing preclinical and clinical studies of immunomodulation and tolerization with rFVIIIFc, as well as studies in joint and bone health, to elucidate the potential benefits of rFVIIIFc in haemophilia A beyond the extension of factor VIII half‐life.

Long-term safety and sustained efficacy for up to 5 years of treatment with recombinant factor IX Fc fusion protein in subjects with haemophilia B: Results from the B-YOND extension study

INTRODUCTION

Recombinant factor IX Fc fusion protein (rFIXFc) has demonstrated efficacy for treatment of haemophilia B in the Phase 3 B-LONG and Kids B-LONG studies. However, long-term rFIXFc safety and efficacy data have not yet been reported.

AIM

To report long-term rFIXFc safety and efficacy in subjects with haemophilia B.

METHODS

B-YOND (NCT01425723) was an open-label extension for eligibl previously treated subjects who completed B-LONG or Kids B-LONG. Subjects received ≥1 treatment regimen: weekly prophylaxis (WP), individualized interval prophylaxis (IP), modified prophylaxis or episodic treatment. Subjects could switch regimens at any time. The primary endpoint was inhibitor development.

RESULTS

Ninety-three subjects from B-LONG and 27 from Kids B-LONG (aged 3-63 years) were enrolled. Most subjects received WP (B-LONG: n = 51; Kids B-LONG: n = 23). For subjects from B-LONG, median (range) treatment duration was 4.0 (0.3-5.4) years and median (range) number of exposure days (EDs) was 146 (8-462) EDs. Corresponding values for paediatric subjects were 2.6 (0.2-3.9) years and 132 (50-256) EDs. No inhibitors were observed (0 per 1000 subject-years; 95% confidence interval, 0-8.9) and the overall rFIXFc safety profile was consistent with prior studies. Annualized bleed rates remained low and extended-dosing intervals were maintained for most subjects. Median dosing interval for the IP group was approximately 14 days for adults and adolescents (n = 31) and 10 days for paediatric subjects (n = 5).

CONCLUSIONS

B-YOND results confirm the long-term (up to 5 years, with cumulative duration up to 6.5 years) well-characterized safety and efficacy of rFIXFc treatment for haemophilia B.

Real-World Utilisation and Bleed Rates in Patients with Haemophilia B Who Switched to Recombinant Factor IX Fusion Protein (rIX-FP): A Retrospective International Analysis

Introduction

Despite the well-documented benefits of prophylaxis, treatment burden is still a barrier to adherence in patients with haemophilia. An extended half-life fusion protein linking recombinant FIX (rFIX) with human albumin (rIX-FP) has been developed for the treatment of patients with haemophilia B and is indicated for dosing up to every 14 days. This analysis evaluated real-world outcomes in patients switching to rIX-FP from the previous FIX product in Italy, Belgium and the UK.

Methods

Anonymised chart data were collected from the pre-existing medical records of patients with haemophilia B between May and September 2018. Patients were included in the analysis if they had been treated with rIX-FP for ≥ 8 weeks. Data were compared between rIX-FP and the patient’s prior FIX product.

Results

Twenty-three HTCs from Italy (n = 13), Belgium (n = 3) and the UK (n = 7) provided data for 84 male patients, 92.8% of which had severe haemophilia B. The majority of patients were previously on prophylactic regimens with their prior FIX product (Italy, 44/49; Belgium, 7/10; UK, 22/25). The switch to prophylaxis with rIX-FP led to reductions in mean annualised bleeding rate of 94.3% in Italy, 93.9% in Belgium and 67.7% in the UK compared with prior FIX prophylaxis. Overall, 41% of patients experienced zero spontaneous bleeds prior to switching, compared with 88% following the switch to rIX-FP. The majority of patients had a reduction in dosing frequency following the switch, with 98.6% of patients dosing once weekly or less frequently compared with 9.6% of patients dosing at this frequency with their prior FIX. Mean weekly FIX consumption was reduced compared with prior FIX prophylaxis.

Conclusion

This retrospective review of real-world evidence demonstrated that switching to rIX-FP from prior FIX was associated with improved haemostatic efficacy and reduced factor consumption in patients with haemophilia B from Italy, Belgium and the UK.

While clinical trials provide robust evidence as to the effectiveness and safety of a new drug, they are tightly controlled and so may not reflect some of the issues that may be discovered in clinical practice. Therefore, real-world analyses are important to determine how a product performs in patients in everyday settings. This study looked at the use of an extended half-life fusion protein linking recombinant FIX (rFIX) with human albumin (rIX-FP), which was designed to allow longer dosing intervals, in patients with haemophilia B in Italy, Belgium and the UK, and compared this with the patients’ previous FIX product. Anonymous patient chart data were collected from participating centres and analysed in terms of bleeding rate, factor usage and dosing frequency for rIX-FP and previous FIX product. The results showed that after switching to rIX-FP, patients experienced lower bleeding rates, lower factor usage and less frequent dosing regimens compared with their previous FIX product. This is the first analysis to assess the real-world clinical benefits of switching to prophylaxis with rIX-FP from a prior FIX product in Italy, Belgium and the UK. This study further strengthens the results seen in clinical trials with rIX-FP, confirming that the effective bleeding prevention demonstrated in clinical trials is consistent with that seen in patients in real-world clinical practice.

The Australian experience with switching to extended half-life factor VIII and IX concentrates: On behalf of the Australian Haemophilia Centre Directors' Organisation

INTRODUCTION

Extended half-life (EHL) factor (F) VIII and FIX concentrates became available to selected haemophilia A (HA) and haemophilia B (HB) patients in Australia in March 2018.

AIM

To determine factor utilization and bleeding outcomes during the first 6 months of prophylaxis with EHL concentrates, and compare it to the last 6 months of prophylaxis with standard half-life (SHL) concentrates.

METHODS

A national, retrospective study was performed using data extracted from the Australian Bleeding Disorders Registry (ABDR). Patients with ≥3 months of EHL exposure were analysed.

RESULTS

A total of 129 HA patients (86 Adynovate, 43 Eloctate) and 64 HB (Alprolix) patients were included in the study. For HA, switching to EHL FVIII resulted in decreased injection frequency (3 to 2 per week), improved 'reduced adherence' rates (18% to 7%), decreased median annualized bleeding rate (ABR; 2.0 to 0.0) and increased proportion of patients with zero bleeds (44% to 64%). Actual factor utilization increased by 20 IU/kg/wk on Adynovate and 4 IU/kg/wk on Eloctate. For HB, switching to EHL FIX resulted in decreased injection frequency (2 to 1 per week), improved 'reduced adherence' rates (35% to 11%), decreased median ABR (3.0 to 2.0) and increased proportion of patients with zero bleeds (31% to 46%). Actual factor utilization decreased by 4 IU/kg/wk. There was no clinically significant inhibitor development.

CONCLUSION

Compared to SHL, EHL FVIII resulted in improved bleeding outcomes, albeit at the expense of increased factor utilization. EHL FIX resulted in improved bleeding outcomes despite decreased factor utilization.

A Retrospective Observational Study of Rurioctocog Alfa Pegol in Clinical Practice in the United States

BACKGROUND

Research describing patient experience and outcomes with extended half-life recombinant factor VIII (EHL rFVIII) outside of clinical trials is limited. Real-world rFVIII consumption studies, when people with hemophilia A (PWHA) switch from standard half-life (SHL) to EHL rFVIII, may help payers and clinicians make more informed treatment choices.

OBJECTIVE

To conduct a retrospective, observational, U.S.-based analysis to describe clinical and demographic profiles of PWHA who switched to prophylactic rurioctocog alfa pegol.

METHODS

Data were obtained from PWHA treated by 38 prescribers across 21 states using specialty pharmacy database case report forms, electronic medical records, and direct communication with providers, PWHA, or their guardians. Assessments included disease severity, pain severity, number and location of target joints, prior HA therapy, reasons for switching, treatment duration, dosing frequency, adherence, and annualized bleeding rates (ABRs) before and after switching to rurioctocog alfa pegol from SHL or another EHL rFVIII.

RESULTS

Data were collected from 56 PWHA. The mean age was 26 years (range = 5-88); median age was 24 years (interquartile range = 14-34); 20% were aged < 12 years; and 89% (50/56) had severe HA. All PWHA had ≥ 12 months of rFVIII treatment before switching to rurioctocog alfa pegol. The population had a mean 1.8 target joints. Baseline subjective pain assessment was mild to moderate for 68% (38/56) of respondents. Before receiving rurioctocog alfa pegol, most PWHA received antihemophilic factor (recombinant) for prophylaxis (73%, 41/56) or breakthrough bleeding (59%, 33/56). Mean dosing frequency for prior prophylaxis was 2.8 per week for SHL rFVIII and 1.8 per week for EHL rFVIII, and 2.2 per week for all PWHA after switching to rurioctocog alfa pegol prophylaxis. The median time on rurioctocog alfa pegol prophylaxis was 12.0 months versus 80.8 months on previous SHL rFVIII and 13.5 months on previous EHL rFVIII. Mean ABRs on prior prophylaxis were 5.9 for SHL rFVIII (n = 35) and 4.7 for EHL rFVIII (n = 3). After switching to rurioctocog alfa pegol, the overall mean ABR reduced by 71% (5.8 to 1.7, P < 0.001) and 20/56 PWHA had no bleeding events. There was also a 20.9% reduction in the mean days per week of factor administration (P < 0.001) after switching to prophylactic rurioctocog alfa pegol. For 47 PWHA who switched from SHL rFVIII, their weekly dose decreased from 109.8 to 100.6 IU per kg with rurioctocog alfa pegol (P = 0.094). The proportion of PWHA with good/complete treatment adherence increased from 68% (38/56) on any prior rFVIII to 80% (45/56) on rurioctocog alfa pegol. The most common reason PWHA switched to rurioctocog alfa pegol was to reduce treatment infusions.

CONCLUSIONS

Switching from either an SHL or EHL rFVIII to rurioctocog alfa pegol is associated with fewer bleeding episodes owing to more effective prophylaxis and improved adherence. Those who switched from an SHL rFVIII reported reduced factor consumption with rurioctocog alfa pegol. This long-acting factor is an important additional option for the care of PWHA.

DISCLOSURES

This study was funded by Shire Development LLC, a Takeda company, Lexington, MA. Trio Health was involved in study design and acquisition, analysis, and interpretation of data and was funded by Shire Development LLC, a Takeda company. Aledort serves on the data and safety monitoring boards of Baxalta U.S. Inc., a Takeda company, and Octapharma; is chair of the scientific advisory board of Kedrion; and receives consultancy fees and honoraria from Baxalta U.S. Inc., a Takeda company. Milligan is an employee of Trio Health and reports research support from AbbVie, Gilead, Merck, Sanofi, and ViiV, unrelated to this study. Watt is an employee of Shire International GmbH, a Takeda company, and owns stock in the company. Booth was an employee of Baxalta U.S. Inc., a Takeda company, at the time of this study and owns stock in the company. Data from this study were presented at the AMCP Managed Care and Specialty Pharmacy Annual Meeting; April 23-28, 2018; Boston, MA; SETH (2018) Sociedad Espanola de Trombosis y Hemostasia-XXXIV Congreso Nacional; October 11-13, 2018; Grenada, Espana; and Blood 2018 Annual Scientific Meeting; October 21-24, 2018; Brisbane, Australia.

Recombinant factor VIII Fc fusion protein for the treatment of severe haemophilia A: Final results from the ASPIRE extension study

Introduction

The efficacy and safety of recombinant factor VIII Fc fusion protein (rFVIIIFc) as an extended half‐life treatment for severe haemophilia A were demonstrated in the Phase 3 A‐LONG and Kids A‐LONG studies. Eligible subjects who completed A‐LONG and Kids A‐LONG could enrol in ASPIRE (NCT01454739), an open‐label extension study.

Aim

To report the long‐term safety and efficacy of rFVIIIFc in subjects with severe haemophilia A who enrolled in ASPIRE.

Methods

Previously treated subjects received one or more of the following regimens: individualized prophylaxis (IP), weekly prophylaxis, modified prophylaxis or episodic treatment. Subjects could switch treatment regimen at any time. The primary endpoint was inhibitor development.

Results

A total of 150 subjects from A‐LONG and 61 subjects from Kids A‐LONG enrolled in ASPIRE. Most subjects received the IP regimen (A‐LONG: n = 110; Kids A‐LONG: n = 59). Median (range) treatment duration in ASPIRE for subjects from A‐LONG and Kids A‐LONG was 3.9 (0.1‐5.3) years and 3.2 (0.3‐3.9) years, respectively. No inhibitors were observed (0 per 1000 subject‐years; 95% confidence interval, 0‐5.2) and the overall rFVIIIFc safety profile was consistent with prior studies. For subjects on the IP regimen, annualized bleed rates (ABR) remained low (median overall ABR for adults and adolescents was <1.0) and extended‐dosing intervals were maintained (median of 3.5 days) for the majority of subjects in ASPIRE.

Conclusion

ASPIRE results, which include up to 5 years of follow‐up data, confirm earlier reports on the consistent and well‐characterized safety and efficacy of rFVIIIFc treatment for severe haemophilia A.

Optimising prophylaxis outcomes and costs in haemophilia patients switching to recombinant FVIII-Fc: a single-centre real-world experience

BACKGROUND

The recombinant factor VIII (rFVIII)-IgG1 Fc fusion protein (rFVIII-Fc) was the first available extended half-life rFVIII, shown to prolong dosing intervals of individualised prophylaxis in patients with severe haemophilia A, maintaining low bleeding rates and unchanged or lower FVIII dose versus standard half-life (SHL) rFVIII. Few data are available about real-world experience with rFVIII-Fc, including criteria for patient switching from SHL products, follow up and prophylaxis optimisation.

MATERIALS AND METHODS

A single-centre retrospective study was designed to review patients switched to rFVIII-Fc, based on individual needs, after pharmacokinetic (PK) assessment, according to routine clinical practice. In patients with adequate post-switch follow up, data about rFVIII-Fc prophylaxis were compared with those from the last 18-months SHL rFVIII prophylaxis.

RESULTS

Of 25 candidates, 18 patients (15 severe, 3 moderate; aged 9-62 years; 3 with inhibitor history) started rFVIII-Fc regimens, with comparable FVIII weekly dose and reduced infusion frequency (mean -30%) in all 17 patients previously on SHL rFVIII prophylaxis thrice weekly or every other day. Over a mean 18-month follow up in 13 patients, compared with SHL products, further reduced infusion frequency (mean -40%; p<0.001; interval ≥4 days in 9 patients), improved treatment satisfaction (Hemo-sat questionnaires), significantly lower FVIII weekly dose and annual consumption (mean -12%; p=0.019), comparable bleeding rates and FVIII trough levels, and improved management of breakthrough bleeding were observed. von Willebrand Factor Antigen (VWF:Ag) correlated to PK variables and both had relationships with rFVIII-Fc weekly dose, increasing statistical significance over the follow-up period. No inhibitors or drug-related adverse events were recorded.

DISCUSSION

In this real-world series of patients, a switch to rFVIII-Fc, based on careful assessment of clinical needs, PK testing and treatment monitoring, was able to optimise individual convenience, efficacy and costs of prophylaxis.

Real-life experience in switching to new extended half-life products at European haemophilia centres

The concept of replacement therapy in haemophilia is changing significantly thanks to the switch from standard products to extended half-life products. These novel drugs are showing beneficial effects overcoming current prophylaxis limitations by reducing the infusion frequency, maintaining a higher trough level to ensure a lower risk of bleeding, and making treatment significantly less distressing to patients by improving the quality of life. Real-life data on the efficacy of novel drugs and their impact on routine management of haemophilia A and B patients are still limited. This manuscript reports the results of a European survey conducted by the European Association for Haemophilia and Allied Disorders (EAHAD) at the beginning of 2018 on the clinical management of patients using extended half-life recombinant FVIII and FIX fusion products, since at the time of the survey none of the PEGylated products were available yet. We report data on the efficacy of these novel drugs by 33 European haemophilia centres that have already switched to extended half-life fusion products, showing a significant reduction in the number of infusions and a satisfactory trough levels in the clinical care of haemophilia patients, with a greater impact for haemophilia B.

Extended Half-Life Coagulation Factors: A New Era in the Management of Hemophilia Patients

Despite effective factor replacement and various treatment schedules, there remain several challenges and unmet needs in the prophylactic treatment of hemophilia limiting its adoption and thereby posing an increased risk of spontaneous bleeding. In this regard, extended half-life (EHL) recombinant factor VIII (rFVIII) and factor IX (rFIX) products promise optimal prophylaxis by decreasing the dose frequency, increasing the compliance, and improving the quality of life without compromising safety and efficacy. EHL products might lead to higher trough levels without increasing infusion frequency, or could facilitate the ability to maintain trough levels while reducing infusion frequency. This paper aims to provide a comprehensive review of the rationale for developing EHL coagulation factors and their utility in the management of hemophilia, with special emphasis on optimal techniques for half-life extension and criteria for defining EHL coagulation factors, as well as indications, efficacy, and safety issues of the currently available EHL-rFVIII and EHL-rFIX products. Potential impacts of these factors on quality of life, health economics, and immune tolerance treatment will also be discussed alongside the challenges in pharmacokinetic-driven prophylaxis and difficulties in monitoring the EHL products with laboratory assays.