Variability of treatment modalities and intensity in patients with severe haemophilia A on prophylaxis: Results from the Italian national registry.

BACKGROUND: A shift from a standard to a personalized prophylaxis has been increasingly adopted in patients with severe haemophilia A (SHA). This approach has raised the likelihood of a significant variability in the prophylactic approaches and the relative Factor VIII (FVIII) consumptions. The aim of our study was to assess the treatment variability of SHA patients without inhibitors and on prophylaxis regimen in Italy. MATERIAL AND METHODS: Data reported in the National Registry of Congenital Coagulopathies (NRCC) were analysed to assess treatment distribution within SHA patients without inhibitors, focussing on FVIII consumption in 2017, associated with prophylaxis regimen. The analysis was stratified based on age groups and Italian regions to describe the variability of FVIII consumption in Italy. RESULTS: In 2017, the Registry reported the therapeutic plans of 1068 SHA patients without inhibitors on prophylaxis. The mean (95% CI) individual consumption ranges from 123 127 IU (99 736-146 518) in the age group 0-6 years to 345 000 IU (336 000-354 000) in the age group >20 years. A significant FVIII consumption variability was identified within the adult population. Regions with less than 50 patients reported the higher variability in mean FVIII consumption per patient-year within the different age groups. Similar difference in FVIII consumption variability was reported also in the age groups comparing "low," "middle" and "high" patient volume regions. DISCUSSION: A reliable estimation of FVIII consumption for patients' treatment is necessary to manage and plan the appropriate budget and keep treatment's costs affordable. However, without the implementation of a methodology aiming to assess the overall value produced by these FVIII consumptions, the scenario will keep driven by FVIII consumptions, its costs and the budget available. An effort by haemophilic community, haemophilia treatment centres and institutions is required to develop and share this cultural shift in improving haemophilia management and assessment.

Use of population PK/PD approach to model the thrombin generation assay: assessment in haemophilia A plasma samples spiked by a TFPI antibody.

The thrombin generation (TG) assay is a well-established tool to capture the clotting potential of any healthy or haemophiliac subject. It measures ex vivo the kinetics of thrombin activation throughout the coagulation. Clinical studies allowed to create two databases gathering the coagulation factor levels and the thrombin generation profile of 40 healthy and 40 haemophiliac A (HA) subjects. Besides, portions of all HA samples were spiked with increasing levels of a TFPI antibody (considered as a possible therapeutic target) and corresponding TG profiles were determined. The non-linear mixed-effect (NLME) modelling aims at describing and explaining the experimentally observed important variability of the TG curves between subjects and the individual effects of spiking with a TFPI antibody. The models consist of an empirical description of the TG kinetics, accounting for an additive residual error and between-subject variability on its parameters. Factor VIII and TFPI were found to significantly explain and reduce the variability of the TG of haemophilia A samples. Besides, the model is shown to correctly reproduce the variability in the response to the ex vivo spiking with the TFPI antibody, by combining the empirical description of TG to a simple Hill equation that accounts for the binding between TFPI and different doses of its antibody. Such models can be useful for clinical practice, with the analysis and comparison of the distributions of TG profiles in healthy and haemophilia populations; and also for research, with the analysis of the effect of TFPI and its neutralization on individual TG profiles.

Comparison of the Pharmacokinetic Properties of Extended Half-Life and Recombinant Factor VIII Concentrates by In Silico Simulations.

BACKGROUND: The pharmacokinetic (PK) properties of extended half-life (EHL) factor VIII (FVIII) concentrates differ, leading to variation in the optimal dosing regimen for the individual patient. The aim of this study was to establish these PK differences for various EHL FVIII concentrates by in silico simulations. METHODS: FVIII level over time profiles of rFVIII-SC, BAY 81-8973, rFVIII-Fc, BAX 855, BAY 94-9027, and standard half-life (SHL) rFVIII concentrates were simulated for 1,000 severe hemophilia A patients during steady-state dosing of 40 IU/kg every 72 hours or dosing as advised in the summary of product characteristics (SmPC). RESULTS: Although the elimination half-life values were comparable for rFVIII-FC, BAX 855, and BAY 94-9027, a higher area under the curve (AUC; 2,779 IU/h/dL) for BAY 94-9027 was obtained. During steady-state dosing of 40 IU/kg every 72 hours, 58.5% (rFVIII-SC), 69.3% (BAY 81-8972), 89.0% (rFVIII-Fc), 83.9% (BAX 855), and 93.7% (BAY 94-9027) of the patients maintained a trough level of 1 IU/dL, compared with 56.0% for SHL rFVIII. Following dosing schemes described in the SmPC, between 51.0 and 65.4% or 23.2 and 31.1% of the patients maintained a target trough level of 1 IU/dL or 3 IU/dL, respectively. CONCLUSION: BAY 94-9027 showed the largest increase of AUC and best target attainment compared with SHL rFVIII, followed closely by BAX 855 and rFVIII-Fc. BAY 81-8973 and rFVIII-SC showed smaller PK improvements. Although our analyses increase insight into the PK of these FVIII concentrates, more studies evaluating the relation between factor levels and bleeding risk are needed.

A Novel Assessment of Factor VIII Activity by Template Matching Utilizing Weighted Average Parameters from Comprehensive Clot Waveform Analysis.

BACKGROUND: Activated partial thromboplastin time (aPTT)-based clot waveform analysis is used to evaluate the comprehensive dynamics of fibrin clot formation. In addition, the technique can be usefully utilized for the rapid assessment of factor (F)VIII procoagulant activity in various clinical settings in patients with hemophilia A (HA). We defined a novel algorithm based on the weighted average parameters from aPTT-based waveforms to devise a template-matching procedure for assessing FVIII activity (FVIII:C). METHODS: The first derivatives of original clot waveforms triggered by the aPTT reagent (Coagpia APTT-N) were used to determine weighted averages of areas surrounded by the waveform at different percentages of maximum height in various clotting factor-deficient plasmas. Prepared templates based on 50 weighted average-related parameters were compared with 78 aPTT-prolonged plasmas. RESULTS: Original nonsmoothed waveforms of the various clotting factor-deficient plasmas with prolonged aPTTs demonstrated a variety of shapes. The weighted averages were calculated after adjustments for different baselines, and the patterns seemed to be governed by the specific clotting factor deficiency. The weighted average-related parameters including baseline wedge (r 2 = 0.998) and aspect ratio (r 2 = 0.998) were highly correlated with FVIII:C levels. Template-matching analyses based on weighted average-related waveform parameters obtained from 158 samples demonstrated that the sensitivity was 97.2% and specificity was 83.3% in aPTT-prolonged plasmas (n = 78). CONCLUSION: This novel algorithm based on weighted averages of aPTT-based waveforms together with template-matching may support clinical usefulness for judging of HA and may aid clinical management in the patients in the absence of specific clotting factor assays.

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

INTRODUCTION: Emicizumab is a humanized monoclonal modified IgG4 antibody with bispecific antibody structure bridging Factor IXa and Factor X. Emicizumab has demonstrated efficacy and safety in adults, adolescents and paediatrics with HA, with or without inhibitors to Factor VIII (FVIII). There is currently no evidence that reports on the potential impact of the introduction of emicizumab on the societal costs of haemophilia A (HA). The purpose of this study was to explore the cost impact associated with the introduction of emicizumab on the current societal costs of people with HA (PwHA) in Australia. METHODS: We conducted an analysis of the impact of emicizumab on societal costs, based on changes in the direct and indirect costs incurred by PwHA. Potential impacts of emicizumab on outcomes in PwHA were modelled based on HAVEN 1, HAVEN 2 and HAVEN 3 studies. We assumed that eligible PwHA commenced use of emicizumab on 1 January 2018. The impact of emicizumab on costs of HA in Australia males was then estimated for the 12-month period to 31 December 2018. RESULTS: Overall, uptake of emicizumab in its first year of use reduces annual costs associated with moderate/severe HA by AUD$69.197M (62.3%). This reflects 64.2% reduction in the cost of FVIII blood products and 92% reduction in cost of bypassing agents. CONCLUSION: The cost of emicizumab is likely to offset some or all of the projected reductions in treatment costs. However, we also found 30.7% reduction in non-treatment direct costs (AUD$3.771M) and 19.1% reduction in indirect costs (AUD$2.732M).

A hemophilia A mouse model for the in vivo assessment of emicizumab function.

The bispecific antibody emicizumab is increasingly used for hemophilia A treatment. However, its specificity for human factors IX and X (FIX and FX) has limited its in vivo functional analysis to primate models of acquired hemophilia. Here, we describe a novel mouse model that allows emicizumab function to be examined. Briefly, FVIII-deficient mice received IV emicizumab 24 hours before tail-clip bleeding was performed. A second infusion with human FIX and FX, administered 5 minutes before bleeding, generated consistent levels of emicizumab (0.7-19 mg/dL for 0.5-10 mg/kg doses) and of both FIX and FX (85 and 101 U/dL, respectively, after dosing at 100 U/kg). Plasma from these mice display FVIII-like activity in assays (diluted activated partial thromboplastin time and thrombin generation), similar to human samples containing emicizumab. Emicizumab doses of 1.5 mg/kg and higher significantly reduced blood loss in a tail-clip-bleeding model using FVIII-deficient mice. However, reduction was incomplete compared with mice treated with human FVIII concentrate, and no difference in efficacy between doses was observed. From this model, we deducted FVIII-like activity from emicizumab that corresponded to a dose of 4.5 U of FVIII per kilogram (ie, 9.0 U/dL). Interestingly, combined with a low FVIII dose (5 U/kg), emicizumab provided enough additive activity to allow complete bleeding arrest. This model could be useful for further in vivo analysis of emicizumab.

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.

Recombinant FIX Fc fusion protein activity assessment with the one-stage clotting assay: A multicenter, assessor-blinded, prospective study in Japan (J-Field Study).

INTRODUCTION: The one-stage clotting assay is used to measure factor IX (FIX) activity in patients' plasma samples and in FIX products for hemophilia treatment. However, the diversity of reagents and instruments has resulted in significant FIX assay variability. METHODS: The accuracy of the one-stage clotting assay to measure recombinant FIX Fc fusion protein (rFIXFc) activity was evaluated by major Japanese hemophilia treatment centers and commercial laboratories that measure factor IX activity for a majority of hemophilia B patients in Japan. Plasma-derived FIX (pdFIX) and recombinant FIX (rFIX) products were used as comparators. FIX-deficient plasma was spiked with four levels of FIX products based on label potency and measured under blinded conditions by routine one-stage clotting assay procedures in 19 participating laboratories. Interlaboratory coefficient of variation and spike recovery were calculated. RESULTS: Interlaboratory coefficient of variation of rFIXFc was not significantly different from that of rFIX, but appeared larger than that of pdFIX. Mean spike recovery for rFIXFc was generally comparable to rFIX and pdFIX. However, larger discrepancies between pdFIX and rFIX were observed in three of nine laboratories using ellagic acid-based activated partial thromboplastin time reagents. CONCLUSION: Recombinant FIX Fc fusion protein activity was found to be similar to that of rFIX or pdFIX by the one-stage clotting assay. However, minimizing interlaboratory variability is vital for optimizing future patient care.

Cost of Patients With Hemophilia A and High-Titer Inhibitors in Colombia.

BACKGROUND: In Colombia, hemophilia is considered a high-cost disease, and hemophilia A with high-titer inhibitors may be responsible for a significant economic pressure on the Colombian health system. OBJECTIVES: To estimate the direct cost of care for patients with hemophilia A with high-titer inhibitors in Colombia, from the perspective of the health system. METHODS: A cost-of-illness study was carried out using standard case methodology, which was designed based on literature review and validation by expert consensus. Scenarios were established for adults and children, including cases of prophylaxis, immune tolerance induction, bleeding, and surgery. The frequencies were taken from the official report for Colombia, issued by the High-Cost Account 2017 (reported 2018). The prices were obtained from the list of regulated medicines in the country. The cost estimate is presented with a range of values by weight (between 10 kg and 90 kg). RESULTS: The total estimated cost per year for Colombia was US $44 905 252 (between US $32 260 497 and US $58 202 393). The average cost per year calculated for a patient was US $498 947 (between US $358 450 and US $646 693). A total of 99.8% of the estimated cost was directly related to the cost of the coagulation factors and bypassing agents. CONCLUSIONS: Hemophilia A with high-titer inhibitors is a disease that generates significant pressure on the Colombian health system, mainly linked to the cost of factors and bypassing agents.

The socioeconomic burden of patients affected by hemophilia with inhibitors.

Hemophilia is associated with a high financial burden on individuals, healthcare systems, and society. The development of inhibitors significantly increases the socioeconomic burden of the diseases. This study aimed to review and describe the burden of hemophilia with inhibitors, providing a reference scenario to assess the impact of new products in the real word. Two systematic literature reviews were performed to collect data on (i) health economics and (ii) health-related quality of life evidences in hemophilic patients with inhibitors. The costs associated with patients with hemophilia and inhibitors are more than 3 times greater than the costs incurred in those without inhibitors, with an annual cost per patient that can be higher than €1 000 000. The costs of bypassing agents account for the large majority of the total healthcare direct costs for hemophilia treatment. The quality of life is more compromised in patients with hemophilia and inhibitors compared to those without inhibitors, in particular the physical domains, whereas mental domains were comparable to that of the general population. The development of an inhibitor has a high impact on costs and quality of life. New treatments have the potential to change positively the management and socioeconomic burden of hemophilia with inhibitors.

Assessment of Relative Bioavailability of Moroctocog Alfa and Moroctocog Alfa (AF-CC) in Subjects With Severe Hemophilia A.

An open-label, single-dose, randomized, two-period, crossover study comparing the pharmacokinetics of factor VIII activity in plasma (FVIII:C) after administration of an albumin-free presentation of moroctocog alfa (test) and moroctocog alfa manufactured using the previous technique (reference) was conducted in 30 (25 evaluable) male subjects who had severe hemophilia A (FVIII:C < 1 IU/dL). Blood samples were collected for 48 h after administration of each dose. FVIII: C was assayed using a chromogenic substrate assay. The FVIII:C pharmacokinetic parameters were calculated using noncompartmental analysis. The presentations would be bioequivalent if the 90% confidence limits of the ratio of the geometric mean values of AUCinf and recovery fell within the interval of 80-125%. The bioequivalence criteria were met. A total of 10 treatment-related adverse events were observed in a total of nine subjects. All were mild and none was determined to be related to administration of study medication.

Effect of late prophylaxis in hemophilia on joint status: a randomized trial.

Essentials High-quality data are lacking on use of prophylaxis in adults with hemophilia and arthropathy. SPINART was a 3-year randomized clinical trial of late/tertiary prophylaxis vs on-demand therapy. Prophylaxis improved function, quality of life, activity and pain but not joint structure by MRI. Prophylaxis improves function but must start before joint bleeding onset to prevent arthropathy. SUMMARY: Background Limited data exist on the impact of prophylaxis on adults with severe hemophilia A and pre-existing joint disease. Objectives To describe 3-year bleeding, joint health and structure, health-related quality-of-life (HRQoL) and other outcomes from the open-label, randomized, multinational SPINART study. Patients/Methods Males aged 12-50 years with severe hemophilia A, ≥ 150 factor VIII exposure days, no inhibitors and no prophylaxis for > 12 consecutive months in the past 5 years were randomized to sucrose-formulated recombinant FVIII prophylaxis or on-demand therapy (OD). Data collected included total and joint bleeding events (BEs), joint structure (magnetic resonance imaging [MRI]), joint health (Colorado Adult Joint Assessment Scale [CAJAS]), HRQoL, pain, healthcare resource utilization (HRU), activity, and treatment satisfaction. Results Following 3 years of prophylaxis, adults maintained excellent adherence, with a 94% reduction in BEs despite severe pre-existing arthropathy; 35.7% and 76.2% of prophylaxis participants were bleed-free or had fewer than two BEs per year, respectively. As compared with OD, prophylaxis was associated with improved CAJAS scores (least squares [LS] mean, - 0.31 [n = 42] versus + 0.63 [n = 42]) and HAEMO-QoL-A scores (LS mean, + 3.98 [n = 41] versus - 6.00 [n = 42]), less chronic pain (50% decrease), and approximately two-fold less HRU; activity, Euro QoL-5D-3L (EQ-5D-3L) scores and satisfaction scores also favored prophylaxis. However, MRI score changes were not different for prophylaxis versus OD (LS mean, + 0.79 [n = 41] versus + 0.96 [n = 38]). Conclusions Over a period of 3 years, prophylaxis versus OD in adults with severe hemophilia A and arthropathy led to decreased bleeding, pain, and HRU, better joint health, activity, satisfaction, and HRQoL, but no reduction in structural arthropathy progression, suggesting that pre-existing joint arthropathy may be irreversible.

Outcome measures for adult and pediatric hemophilia patients with inhibitors.

Recent advancements in almost all aspects of hemophilia treatment have vastly improved patient care and management, and new and emerging treatments hold the promise of further progress. However, there remains a scarcity of data on long-term outcomes in hemophilia, particularly among those patients with inhibitors, for whom no validated outcome assessment tools are currently available. At the 15th Zürich Haemophilia Forum, an expert panel reviewed the most important outcome measures in inhibitor patients and considered the challenges associated with assessing outcomes in this population. A framework for outcome assessment in inhibitor patients incorporates traditional hemophilia outcome measures, such as bleed frequency and mortality, alongside measures of health, functioning, disability, social participation, quality of life, and economic considerations. It is important to remember that inhibitor patients differ in their clinical needs, perspectives, and priorities according to age, inhibitor status, degree of joint disease, and activity levels; as a result, the relative importance of different outcome measures will change throughout an inhibitor patient's life. Challenges inherent in measuring long-term outcomes in inhibitor patients include the small number of known patients, the subjective nature of many outcome assessment tools, and the risk of overburdening patients with repeated requests to complete questionnaires or participate in studies. Therefore, there is an urgent need to reach consensus on the most important and appropriate assessment tools for measuring outcomes in this population. These tools should ideally be standardized, easily applied, and internationally applicable in order to collect and generate quality outcome data.

Post hoc assessment of the immunogenicity of bioengineered factor VIIa demonstrates the use of preclinical tools.

Immunogenicity is an important consideration in the licensure of a therapeutic protein because the development of neutralizing anti-drug antibodies (ADAs) can affect both safety and efficacy. Neoantigens introduced by bioengineering of a protein drug are a particular cause for concern. The development of a bioengineered recombinant factor VIIa (rFVIIa) analog was discontinued after phase 3 trials because of the development of ADAs. The unmodified parent molecule (rFVIIa), on the other hand, has been successfully used as a drug for more than two decades with no reports of immunogenicity in congenital hemophilia patients with inhibitors. We used computational and experimental methods to demonstrate that the observed ADAs could have been elicited by neoepitopes in the engineered protein. The human leukocyte antigen type of the patients who developed ADAs is consistent with this hypothesis of a neoepitope-driven immune response, a finding that might have implications for the preclinical screening of therapeutic protein analogs.

Hemophilia and inhibitors: current treatment options and potential new therapeutic approaches.

The immune response to infused factor concentrates remains a major source of morbidity and mortality in the treatment of patients with hemophilia A and B. This review focuses on current treatment options and novel therapies currently in clinical trials. After a brief review of immune tolerance regimens, the focus of the discussion is on preventing bleeding in patients with hemophilia and inhibitors. Recombinant factor VIIa and activated prothrombin complex concentrates are the mainstays in treating bleeds in patients with inhibitors. Both agents have been shown to reduce bleeding episodes to a similar degree when infused prophylactically; however, individual patients may respond better to one agent over the other at any given time. The international immune tolerance trial revealed that a high-dose factor VIII regimen provided significantly better bleeding protection than the low-dose regimen. Given the high cost of treatment and the potential for a high-dose immune tolerance regimen to prevent bleeding in some patients, we discuss how we treat patients to maximize the prevention of bleeds while minimizing cost. Novel approaches to treatment of these patients are in development. These include agents that mimic factor VIII or augment thrombin generation by bypassing the inhibitor, as well as agents that inhibit the natural anticoagulants.

Assessment of the frequency of regulatory T cells (CD4+CD25+CD127-) in children with hemophilia A: relation to factor VIII inhibitors and disease severity.

A rapidly growing evidence showed that regulatory T cells (Tregs) play a crucial role in tolerance to coagulation factors and may be involved in the pathogenesis of inhibitor formation in patients with hemophilia. We determined the percentage of Tregs (CD4CD25CD127) in 45 children with hemophilia A compared with 45 healthy controls, and assessed their relation to the clinical characteristics of patients and factor VIII (FVIII) inhibitors. Patients were studied stressing on frequency of bleeding attacks, joint pain, history of viral hepatitis, and the received therapy (FVIII precipitate/cryotherapy). FVIII activity and FVIII inhibitors were assessed with flow cytometric analysis of CD4CD25CD127 Tregs. According to residual FVIII activity levels, 30 patients (66.7%) had mild/moderate hemophilia A, whereas 15 (33.3%) patients had severe hemophilia A. The frequency of Tregs was significantly lower among all patients with hemophilia A compared with controls (2.59 ± 1.1 versus 3.73 ± 1.12%; P = 0.002). Tregs were significantly decreased among patients with FVIII inhibitors compared with the inhibitor-negative group (P < 0.001). Patients with hematuria or severe hemophilia A had lower Tregs levels than those without (P = 0.34 and P = 0.011, respectively). A significant positive correlation was found between the percentage of Tregs and FVIII among hemophilia A patients. ROC curve analysis revealed that the cut-off value of Tregs at 1.91% could differentiate patients with and without FVIII inhibitors, with a sensitivity of 100% and a specificity of 91.3%. We suggest that alteration in the frequency of Tregs in young patients with hemophilia A may contribute to inhibitor formation and disease severity.