Rurioctocog alfa pegol PK-guided prophylaxis in hemophilia A: results from the phase 3 PROPEL study.

Rurioctocog alfa pegol prophylaxis targeting factor VIII (FVIII) troughs ≥1% has shown to be efficacious with an acceptable safety profile in people with hemophilia A (PwHA). The PROPEL trial compared safety and efficacy of 2 target FVIII troughs in PwHA aged 12 to 65 years, with severe disease, annualized bleeding rate ≥2, and previous FVIII treatment. PwHA were randomized to 12 months' pharmacokinetic (PK)-guided rurioctocog alfa pegol prophylaxis targeting FVIII troughs of 1% to 3% (reference arm) or 8% to 12% (elevated arm); first 6 months was treatment-adjustment period. The primary endpoint was absence of bleeds during the second 6 months, analyzed using multiple imputations (full analysis set [FAS]). In the 1% to 3% and 8% to 12% arms, respectively, point estimates (95% confidence interval) of proportions of PwHA with zero total bleeds were 42% (29% to 55%) and 62% (49% to 75%) in FAS (N = 115; P = .055) and 40% (27% to 55%) and 67% (52% to 81%) in per-protocol analysis set (N = 95; P = .015). Dosing frequency and consumption varied in each arm. Adverse events (AEs) occurred in 70/115 (60.9%) PwHA; serious AEs in 7/115 (6%) PwHA, including 1 treatment-related in 8% to 12% arm (transient anti-FVIII inhibitor). There were no deaths, serious thrombotic events, or AE-related discontinuations. PK-guided prophylaxis was achievable and efficacious in both arms. No new safety signals were observed in the 8% to 12% arm. These results demonstrate elevated FVIII troughs can increase the proportion of PwHA with zero bleeds and emphasize the importance of personalized treatment. This trial was registered at www.clinicaltrials.gov as #NCT02585960.

Biological mechanisms underlying inter-individual variation in factor VIII clearance in haemophilia.

Previous studies have highlighted marked inter-individual variations in factor VIII (FVIII) clearance between patients with haemophilia (PWH). The half-life of infused FVIII has been reported to vary from as little as 5.3 hours in some adult PWH, up to as long as 28.8 hours in other individuals. These differences in clearance kinetics have been consistently observed using a number of different plasma-derived and recombinant FVIII products. Furthermore, recent studies have demonstrated that half-life for extended half-life (EHL-) FVIII products also demonstrates significant inter-patient variation. Since time spent with FVIII trough levels <1% has been shown to be associated with increased bleeding risk in PWH on prophylaxis therapy, this variability in FVIII clearance clearly has major clinical significance. Recent studies have provided significant novel insights into the cellular basis underlying FVIII clearance pathways. In addition, accumulating data have shown that endogenous plasma VWF levels, ABO blood group and age, all play important roles in regulating FVIII half-life in PWH. Indeed, multiple regression analysis suggests that together these factors account for approximately 34% of the total inter-individual variation in FVIII clearance observed between subjects with severe haemophilia A. In this review, we consider these and other putative modulators of FVIII half-life, and discuss the biological mechanisms through which these factors impact upon FVIII clearance in vivo.

Concizumab restores thrombin generation potential in patients with haemophilia: Pharmacokinetic/pharmacodynamic modelling results of concizumab phase 1/1b data.

INTRODUCTION: Concizumab enhances thrombin generation (TG) potential in haemophilia patients by inhibiting tissue factor pathway inhibitor (TFPI). In EXPLORER3 (phase 1b), a dose-dependent pharmacokinetic/pharmacodynamic (PK/PD) relationship was confirmed between concizumab dose, free TFPI and TG potential. AIM: Determine the association between concizumab exposure, PD markers (free TFPI; peak TG) and bleeding episodes to establish the minimum concizumab concentration for achieving sufficient efficacy. METHODS: Free TFPI predictions were generated using an estimated concizumab-free TFPI exposure-response (Emax ) model based on concizumab phase 1/1b data for which simultaneously collected concizumab and free TFPI samples were available. Concizumab concentration at the time of a bleed was predicted using a PK model, based on available data for concizumab doses >50 µg/kg to ≤9 mg/kg. Peak TG vs concizumab concentration analyses and an Emax model were constructed based on EXPLORER3 observations. RESULTS: The Emax model showed a tight PK/PD relationship between concizumab exposure and free TFPI; free TFPI decreased with increasing concizumab concentration. A strong correlation between concizumab concentration and peak TG was observed; concizumab >100 ng/mL re-established TG potential to within the normal reference range. Estimated EC50 values for the identified concizumab-free TFPI and concizumab-TG potential models were very similar, supporting free TFPI as an important biomarker. A correlation between bleeding episode frequency and concizumab concentration was indicated; patients with a concizumab concentration >100 ng/mL experienced less frequent bleeding. The PK model predicted that once-daily dosing would minimize within-patient concizumab PK variability. CONCLUSION: Concizumab phase 2 trials will target an exposure ≥100 ng/mL, with a once-daily regimen.

Handling interoccasion variability in model-based dose individualization using therapeutic drug monitoring data.

AIMS: This study aims to assess approaches to handle interoccasion variability (IOV) in a model-based therapeutic drug monitoring (TDM) context, using a population pharmacokinetic model of coagulation factor VIII as example. METHODS: We assessed 5 model-based TDM approaches: empirical Bayes estimates (EBEs) from a model including IOV, with individualized doses calculated based on individual parameters either (i) including or (ii) excluding variability related to IOV; and EBEs from a model excluding IOV by (iii) setting IOV to zero, (iv) summing variances of interindividual variability (IIV) and IOV into a single IIV term, or (v) re-estimating the model without IOV. The impact of varying IOV magnitudes (0-50%) and number of occasions/observations was explored. The approaches were compared with conventional weight-based dosing. Predictive performance was assessed with the prediction error percentiles. RESULTS: When IOV was lower than IIV, the accuracy was good for all approaches (50th percentile of the prediction error [P50] <7.4%), but the precision varied substantially between IOV magnitudes (P97.5 61-528%). Approach (ii) was the most precise forecasting method across a wide range of scenarios, particularly in case of sparse sampling or high magnitudes of IOV. Weight-based dosing led to less precise predictions than the model-based TDM approaches in most scenarios. CONCLUSIONS: Based on the studied scenarios and theoretical expectations, the best approach to handle IOV in model-based dose individualization is to include IOV in the generation of the EBEs but exclude the portion of unexplained variability related to IOV in the individual parameters used to calculate the future dose.

Factor Activity Assays for Monitoring Extended Half-Life FVIII and Factor IX Replacement Therapies.

The advent of modified factor VIII (FVIII) and factor IX (FIX) molecules with extended half-lives (EHLs) compared with native FVIII and FIX represents a major advance in the field of hemophilia care, with the potential to reduce the frequency of prophylactic injections and/or to increase the trough level prior to subsequent injections. Monitoring treatment through laboratory assays will be an important part of ensuring patient safety, including any tailoring of prophylaxis. Several approaches have been used to extend half-lives, including PEGylation, and fusion to albumin or immunoglobulin. Some of these modifications affect factor assays as routinely performed in hemophilia centers; so, laboratories will need to use FVIII and FIX assays which have been shown to be suitable on a product-by-product basis. For some products, there are marked differences between results obtained using one-stage or chromogenic assays and results obtained using different reagents in the one-stage assay. The laboratory should use an assay in which the recovery of the product closely aligns with the assay used by the pharmaceutical company to assign potency to the product, so that the units reported by the laboratory agree with those used to demonstrate efficacy of the product during clinical trials. Reported assay differences in relation to several of the EHL FVIII and FIX molecules will be reviewed in this article.

Impact of being overweight on factor VIII dosing in children with haemophilia A.

INTRODUCTION: Treatment of haemophilia A (HA) requires infusions of factor VIII (FVIII) concentrates. The number of FVIII units infused to obtain a specific circulating FVIII level is calculated with the formula: [body weight (BW) (kg) × desired FVIII increase (%)]/2, with the assumption that each unit of FVIII infused per kg of BW increases the circulating FVIII level by 2%. AIM: The aim of this study was to evaluate the impact of several morphometric parameters (BW, body mass index (BMI)-for-age, height), age and type of FVIII concentrate on FVIII recovery in children with HA. METHODS: A total of 66 children aged between 10 and 18 with severe HA selected from six pharmacokinetic (PK) clinical trials using two recombinant FVIII concentrates were included in the analysis. Regression tree (RT) was used to identify predictors of FVIII recovery. RESULTS: The median age was 14.5 years with a median FVIII recovery of 2.09 for all children. The median FVIII recovery was not significantly different between age groups. Two groups were created by RT: children with a BMI-for-age percentile

Comparative pharmacokinetics of rVIII-SingleChain and octocog alfa (Advate(®) ) in patients with severe haemophilia A.

BACKGROUND: rVIII-SingleChain, a novel recombinant factor VIII (rFVIII), has been designed as a B-domain truncated construct with covalently bonded heavy and light chains, aiming to increase binding affinity to von Willebrand factor (VWF). Preclinical studies confirmed greater affinity for VWF, giving improved pharmacokinetic and pharmacodynamic properties compared with full-length rFVIII. AIM: To investigate the pharmacokinetics of rVIII-SingleChain and compare them against those of full-length rFVIII. METHODS: This study enrolled 27 patients with severe haemophilia A in the AFFINITY clinical trial programme. After a 4-day washout period, all patients received a single infusion of 50 IU kg(-1) octocog alfa (Advate(®) ); after a ≥4-day postinfusion washout period, they received a single infusion of 50 IU kg(-1) rVIII-SingleChain. Blood samples for pharmacokinetic assessments of each product were collected before infusion (predose) and at 0.5, 1, 4, 8, 10, 24, 32, 48 and 72 h postinfusion for both products. RESULTS: rVIII-SingleChain had a longer mean half-life (t1/2 ) (14.5 vs. 13.3 h), lower mean clearance (CL) (2.64 vs. 3.68 mL h(-1) kg(-1) ), higher mean residence time (20.4 vs. 17.1 h) and larger mean AUCinf (2090 vs. 1550 IU?h dL(-1) ) than octocog alfa, respectively. The mean AUCinf after rVIII-SingleChain infusion was ~35% larger than after octocog alfa. A similar pattern was observed for AUC0-last . No serious adverse events or inhibitors were reported. CONCLUSIONS: rVIII-SingleChain has a favourable pharmacokinetic profile compared with octocog alfa and was well tolerated. The prolonged t1/2 , larger AUC and reduced CL of rVIII-SingleChain may permit longer dosing intervals, thereby improving patient adherence to prophylactic treatment.

Pharmacokinetics of a high-purity plasma-derived factor X concentrate in subjects with moderate or severe hereditary factor X deficiency.

INTRODUCTION: Hereditary factor X (FX) deficiency affects 1:500 000 to 1:1 000 000 of individuals. There are few published data on the pharmacokinetics (PK) of FX for existing treatments for FX deficiency, and no specific replacement factor concentrate exists. A high-purity plasma-derived FX concentrate (pdFX) has been developed for use as replacement therapy in subjects with hereditary FX deficiency. AIM: This analysis assessed pdFX PK after a single 25 IU kg(-1) bolus dose in subjects with hereditary moderate or severe FX deficiency (plasma FX activity [FX:C] <5 IU dL(-1) ). METHODS: For a baseline PK assessment, blood samples were taken predose and at intervals up to 144 h (7 days) post dose. After ≥6 months of on-demand pdFX treatment and treatment of ≥1 bleed with pdFX, subjects underwent repeat PK assessment. Samples were assayed for plasma FX:C (measured using the clotting and chromogenic assays) and FX antigen. RESULTS: FX:C peaked at 0.4-0.5 h and subsequently declined over the course of 144 h with a biphasic decay curve. PK parameters observed at the baseline (n = 16) and repeat (n = 15) assessments were equivalent, therefore summary PK values were obtained by combining data from both visits (n = 31). The mean terminal half-life and incremental recovery of pdFX was 29.4 h and 2.00 IU dL(-1) per IU kg(-1) respectively. CONCLUSION: This is the most comprehensive PK study to date in subjects with hereditary FX deficiency. These results are consistent with the observed haemostatic efficacy of pdFX and provide the PK data required for the treatment of hereditary FX deficiency using pdFX replacement therapy.

Correlation between FIX genotype and pharmacokinetics of Nonacog alpha according to a multicentre Italian study.

INTRODUCTION: Pharmacokinetic (PK) studies on recombinant FIX concentrate, Nonacog alpha, were conducted with different sampling time designs which gave rise to not complete and homogenous outcomes. In addition, patient's FIX genotype/PK relationship has never been investigated. AIM: Investigate how different sampling times may affect PK parameters and try to find a FIX genotype/PK relationship. PATIENTS AND METHODS: A cohort pharmacokinetic, Nonacog Alpha single-dose, open-label, non-comparative study was conducted in eight Comprehensive Care Haemophilia Centres in Italy. Seventeen previously treated moderate or severe haemophilia B patients were enrolled. Factors IX:C one-stage clotting assay, FIX genotype and PK analysis were centralized. RESULTS: The evaluation of PK outcomes showed a quite long half-life, smaller clearance and volume of distribution of Nonacog Alpha in comparison with the results from previously reported studies, where blood sampling was stopped too early. The relationship between PK outcomes and FIX genotype showed that small deletions displayed the higher clearance and shorter half-life, the nonsense mutations (the lower and the longer respectively), and missense mutations were in between. CONCLUSIONS: It is evident that area under the curve (AUC) and other PK parameters depend from the sampling time design. In order to have a complete evaluation of clotting factors in vivo decay, blood samples must be collected until the baseline factor concentration has been achieved again. Due to the relationship between FIX genotype and clearance, tailored prophylaxis of HB patients could be partially predicted by genotyping.

Safety and efficacy of BAY 81-8973 for surgery in previously treated patients with haemophilia A: results of the LEOPOLD clinical trial programme.

INTRODUCTION: BAY 81-8973 is a recombinant factor VIII (rFVIII) with the same amino acid sequence as Bayer's sucrose-formulated rFVIII (rFVIII-FS) but manufactured with certain more advanced technologies. AIM: To describe surgery outcomes with BAY 81-8973 in the LEOPOLD trials. METHODS: Male patients with severe haemophilia A and no inhibitors aged 12-65 years with ≥150 exposure days (EDs) to FVIII (LEOPOLD I and II), or aged ≤12 years with ≥50 EDs to FVIII (LEOPOLD Kids), received BAY 81-8973 based on dosing recommendations for rFVIII-FS according to surgical requirements. Haemostasis-related complications, investigator/surgeon assessment of haemostasis, blood loss, need for transfusion and use of BAY 81-8973 were determined. RESULTS: In LEOPOLD I and II, 11 patients (mean age, 35.3 years) underwent 13 major surgeries. In LEOPOLD Kids, one patient (aged 6 years) underwent one major surgery. Thirty-two adult and paediatric patients underwent 46 minor surgeries. Haemostasis was rated good or excellent in all major and minor surgeries. Blood loss during surgery did not exceed expected amounts; blood transfusions were required in three of the 14 major surgeries. For major surgeries in LEOPOLD I and II, patients received a presurgical 50-IU kg(-1) dose of BAY 81-8973; median nominal dose on day of surgery was 7000 IU (107.5 IU kg(-1) ). Total BAY 81-8973 dose was 2500 IU (108.7 IU kg(-1) ) on the day of the only major surgery in LEOPOLD Kids. No haemostasis-related complications were reported. CONCLUSIONS: Haemostatic control with BAY 81-8973 during all surgeries in the LEOPOLD trials was good or excellent, with no haemostasis-related complications.

Development of a tail vein transection bleeding model in fully anaesthetized haemophilia A mice - characterization of two novel FVIII molecules.

INTRODUCTION: The tail tip bleeding model and the tail vein transection survival model in mice are important tools for assessment of in vivo effect in haemostasis research. While the tail vein transection model exhibits the best sensitivity to pharmacological intervention it uses death or near-death as endpoint which is fully avoided in the tail tip bleeding model. AIM: The aim of this study was to develop a new tail bleeding model maintaining the sensitivity of the previous survival model but avoiding death/near-death as endpoint. METHODS: Combining the two existing tail bleeding models we developed an optimized version of the survival model with full anaesthetic coverage and short duration of experiments. Using this model, we characterized the effect of turoctocog alfa, a B-domain truncated FVIII molecule (NovoEight(®) ), as well as the prolonged half-life version of the same molecule (turoctocog alfa pegol, N8-GP). RESULTS: Data showed that the model was sensitive to clinically relevant doses of both turoctocog alfa as well as N8-GP when dosed for 'on demand' treatment. The model also correctly identified a longer duration of effect for N8-GP compared with turoctocog alfa. Moreover, the model allowed the use of mice of both genders and was reproducible over time. CONCLUSION: The optimized tail vein transection bleeding model is sensitive to standard as well as half-life prolonged FVIII molecules and should be a valuable alternative to both the tail tip bleeding model, enhancing sensitivity to pharmacological intervention, as well as to the previously used tail vein transection survival model, avoiding death or near-death as endpoint.

Association of peak factor VIII levels and area under the curve with bleeding in patients with haemophilia A on every third day pharmacokinetic-guided prophylaxis.

INTRODUCTION: We previously showed that pharmacokinetic-guided prophylaxis (PKP) allows the dosing interval to be extended while maintaining a specific trough level. However, the associations of peak factor VIII (FVIII) levels and area under the curve (AUC) with breakthrough bleeding have not been investigated. AIM: The aim of this study was to analyse data from the PKP arm to determine whether peak FVIII levels, AUC and time with FVIII levels in a haemostatically effective range are independent predictors of bleeding during prophylaxis. METHODS: Post hoc analysis of the association of FVIII levels and AUC with annualized bleeding rate in 34 patients on PKP. RESULTS: During 1 year of PKP, 131 bleeding episodes occurred in 24/34 patients. Average peak FVIII levels ranged from 24 to 168 IU dL(-1) , with higher values associated with a decreased risk for all bleeding (joint and non-joint; P < 0.01) and joint bleeding (P < 0.01). Following rFVIII infusion, median percent of time spent with FVIII levels >20 IU dL(-1) was 22%; median AUC was 1363. Both values were significantly associated with a lower ABR when targeting a 1% trough at 72 h. CONCLUSION: When PKP was administered every third day, higher peak FVIII levels, higher AUC and more time spent per week with FVIII levels >20 IU dL(-1) provided increased protection from joint and non-joint bleeding. These data highlight the potential impact of variability in individual pharmacokinetic and bleeding risk and support the need for high peak levels and AUC in some patients treated every third day. The findings do not necessarily apply to alternate-day or other prophylactic dosing regimens.

Dosing regimens, FVIII levels and estimated haemostatic protection with special focus on rFVIIIFc.

AIM: To use Pharmacokinetic (PK) simulations to illustrate potential differences in clinical outcomes between prophylaxis with conventional recombinant factor VIII (rFVIII) and rFVIIIFc, an extended half-life rFVIII covalently fused to the Fc domain of human IgG1. METHODS: Population PK estimates from 180 (rFVIIIFc) and 46 (rFVIII) severe haemophilia A patients were used to simulate FVIII activity over time at various rFVIIIFc dosing regimens compared to rFVIII 30 IU kg(-1) three times weekly in a typical adult patient. RESULTS: rFVIII dosed 3x30 IU kg(-1) weekly gave trough levels of 2.7, 2.8 and 0.7 IU dL(-1) , and time spent below 1, 3 and 5 IU dL(-1) of 0.2/1.2/2.3 days week(-1) . rFVIIIFc 2 x 45 IU kg(-1) gave higher troughs (4.4 and 1.7 IU dL(-1) ) and shorter time spent below 1, 3 and 5 IU dL(-1) (0/0.6/1.3 days week(-1) ), with same total factor consumption. rFVIIIFc 2 x 30 IU kg(-1) gave similar troughs (3.0 and 1.2 IU kg(-1) ) and time spent below 1, 3 and 5 IU dL(-1) (0/1.0/2.1 days week(-1) ), despite total factor consumption being reduced by one-third. The same dose and interval of rFVIIIFc (3 x 30 IU kg(-1) ) gave substantially higher troughs (7.8, 8.5 and 3.3 IU dL(-1) ) and markedly shorter time spent below 1, 3 and 5 IU dL(-1) (0/0/0.4 days week(-1) ). CONCLUSION: The lower clearance of rFVIIIFc compared to conventional rFVIII gives rFVIIIFc the potential of improved bleed prevention and reduced injection frequency at similar factor consumption. Although additional clinical data are required to confirm the conclusions, the simulations clearly show the potential of rFVIIIFc of increased flexibility to tailor treatment to the individual patient, and to advance the standard of care in haemophilia.

BAY 81-8973 safety and efficacy for prophylaxis and treatment of bleeds in previously treated children with severe haemophilia A: results of the LEOPOLD Kids Trial.

INTRODUCTION: BAY 81-8973, a full-length, unmodified, recombinant factor VIII (FVIII) in development for treatment of haemophilia A, has the same primary amino acid sequence as Bayer's sucrose-formulated recombinant FVIII but is produced with more advanced manufacturing technologies. AIM: To demonstrate safety and efficacy of BAY 81-8973 for prophylaxis and treatment of bleeds in previously treated children. METHODS: In this phase III, multicentre, open-label, nonrandomized study, boys aged ≤12 years with severe haemophilia A and ≥50 exposure days (EDs) to FVIII products received prophylaxis with BAY 81-8973 25-50 IU kg(-1) ≥2 times weekly for ≥50 EDs. The efficacy endpoint was annualized number of total bleeds. Adverse events (AEs) and immunogenicity were assessed. RESULTS: Fifty-one patients were treated (age: <6 years, n = 25; 6-<12 years, n = 26) with a 2× per week (43%) or >2× per week (57%) regimen at study start. Median [quartile 1; quartile 3 (Q1; Q3)] annualized number of bleeds for the combined age groups was 1.90 (0; 6.02) for total bleeds, 0 (0; 2.01) for joint bleeds and 0 (0; 0) for spontaneous bleeds. Median (Q1; Q3) annualized number of total bleeds within 48 h of previous prophylaxis infusion was 1.88 (0; 3.97) for children aged <6 years and 0 (0; 1.96) for children aged 6-<12 years. No drug-related serious AEs or inhibitors were reported. CONCLUSIONS: Prophylaxis with BAY 81-8973 using individualized prophylaxis regimens of 2× per week, 3× per week and every-other-day infusions was efficacious in prevention and treatment of bleeds in children with severe haemophilia A. Treatment with BAY 81-8973 was well tolerated.

Efficacy and safety of BAY 81-8973, a full-length recombinant factor VIII: results from the LEOPOLD I trial.

INTRODUCTION: BAY 81-8973 (Kovaltry(®) ) is a full-length, unmodified recombinant human factor VIII (FVIII) with the same amino acid sequence as sucrose-formulated recombinant FVIII and is produced using additional advanced manufacturing technologies. AIM: To demonstrate efficacy and safety of BAY 81-8973 for treatment of bleeds and as prophylaxis based on two different potency assignments. METHODS: In LEOPOLD I (ClinicalTrials.gov identifier, NCT01029340), males aged 12-65 years with severe haemophilia A and ≥150 exposure days received BAY 81-8973 20-50 IU kg(-1) two or three times per week for 12 months. Potency was based on chromogenic substrate assay per European Pharmacopoeia and label adjusted to mimic one-stage assay potency. Patients were randomized for potency sequence and crossed over potency groups after 6 months, followed by an optional 12-month extension. Primary efficacy endpoint was annualized bleeding rate (ABR). Patients also received BAY 81-8973 during major surgeries. RESULTS: Sixty-two patients received BAY 81-8973 prophylaxis and were included in the analysis. Median ABR was 1.0 (quartile 1, 0; quartile 3, 5.1) without clinically relevant differences between potency periods. Median ABR was similar for twice-weekly vs. three times-weekly dosing (1.0 vs. 2.0). Haemostasis was maintained during 12 major surgeries. Treatment-related adverse event (AE) incidence was ≤7% overall; no patient developed inhibitors. One patient with risk factors for cardiovascular disease developed a myocardial infarction. CONCLUSIONS: BAY 81-8973 was efficacious in preventing and treating bleeding episodes, irrespective of the potency assignment method, with few treatment-related AEs. Caution should be used when treating older patients with cardiovascular risk factors.

The use of enhanced half-life coagulation factor concentrates in routine clinical practice: guidance from UKHCDO.

Enhanced half-life factor VIII and IX products are being introduced into routine clinical practice. Published data report on clinical trials and there are limited data available on how to use these products in routine clinical practice. Many patients, for example, those with a past history of an inhibitor, have been excluded from clinical trials and there are limited data published on children. This guidance document is a consensus statement from the UK Haemophilia Centres Doctors' Organisation and aims to give pragmatic advice on the use of these products in routine practice.

Efficacy and safety of pegylated full-length recombinant factor VIII with extended half-life for perioperative haemostasis in haemophilia A patients.

INTRODUCTION: BAX 855 is a pegylated full-length recombinant factor VIII (rFVIII) with an extended half-life, built on a licensed rFVIII (ADVATE(®) ). BAX 855 demonstrated efficacy and safety in prophylaxis and the treatment of bleeding episodes in previously treated patients (PTPs) with severe haemophilia A. AIM: This phase 3 surgery study evaluates the haemostatic efficacy and safety of BAX 855 for perioperative haemostasis in PTPs with severe haemophilia A undergoing surgery. METHODS: Elective procedures were prospectively classified as major or minor. The dose and frequency of BAX 855 administered perioperatively were to be guided by each patient's pharmacokinetic profile for major procedures or BAX 855 incremental recovery for minor procedures. Haemostatic efficacy was evaluated using a predefined scale. Blood loss was compared to the expected average and maximum blood loss predicted preoperatively. RESULTS: A total of 15 male patients (aged 19-52 years) underwent 15 procedures (11 major and four minor). The overall intra- and perioperative haemostatic efficacy of BAX 855 was 'excellent' in all 15 subjects (100%). Postoperatively, evaluated at postoperative Day 1, all treatments were 'excellent' except for one minor (dental) procedure which was rated 'good'. No related adverse events, allergic reactions, thrombotic events, nor signs of immunogenicity in terms of induction of binding antibodies to FVIII, PEG or PEG-VIII, or FVIII inhibitors were observed. CONCLUSION: These results demonstrate that BAX 855 is safe and haemostatically effective in patients with severe haemophilia A undergoing surgery.

Haemophilia in a real-world setting: the value of clinical experience in data collection.

At the 8th Annual Congress of the European Association for Haemophilia and Allied Disorders (EAHAD) held in Helsinki, Finland, in February 2015, Pfizer sponsored a satellite symposium entitled: 'Haemophilia in a real-world setting: The value of clinical experience in data collection' Co-chaired by Riitta Lassila (Helsinki University Central Hospital, Helsinki, Finland) and Gerry Dolan (Guy's and St Thomas' Hospital, London, UK); the symposium provided an opportunity to explore the practical value of real-world data in informing clinical decision-making. Gerry Dolan provided an introduction to the symposium by describing what is meant by real-world data (RWD), stressing the role RWD can play in optimising patient outcomes in haemophilia and highlighting the responsibility of all stakeholders to collaborate in continuous data collection. Kristian Juusola (Oulu University Hospital, Oulu, Finland) then provided personal experience as a haemophilia nurse around patient views on adherence to treatment regimes, and how collecting insights into real-world use of treatment can shape approaches to improving adherence. The importance of elucidating pharmacokinetic parameters in a real-world setting was then explored by Vuokko Jokela (Helsinki University, Helsinki, Finland). Finally, Alfonso Iorio (McMaster University, Hamilton, Ontario, Canada) highlighted the importance of quality data collection in translating clinical reality into scientific advances.

Rapid rFVIIa enhanced on-demand dosing in haemophilia inhibitor patients.

Recombinant factor VII activated (rFVIIa) is a bypassing agent widely used in haemophilia A and B patients with antibodies against coagulation factors VIII or IX. When used according to the correct doses, rFVIIa may control bleeding, subclinical bleeding and rebleeding, avoiding the effect of neutralising inhibitors. Because of the fast action of the rFVIIa, haemostasis occurs promptly and enables a fast bleeding control with on-demand treatment in home or in surgical setting. Rapidity is also a distinguishing feature in preparation and injection of rFVIIa to cope the restraining times of busy patients and parents. The effective haemostatic activity of rFVIIa enables a sustained bleeding control, which is implemented with every other day (eod) administration and suited for enhanced on-demand therapy and short-term repeated infusions use of rFVIIa to prevent microhaemorrhages or rebleeding. Comprehensive appreciation of these pharmacological and pharmacodynamic' characteristics will likely be a further stimulus to the wider enhanced on-demand use of rFVIIa.

Prolonged activity of a recombinant factor VIII-Fc fusion protein in hemophilia A mice and dogs.

Despite proven benefits, prophylactic treatment for hemophilia A is hampered by the short half-life of factor VIII. A recombinant factor VIII-Fc fusion protein (rFVIIIFc) was constructed to determine the potential for reduced frequency of dosing. rFVIIIFc has an ∼ 2-fold longer half-life than rFVIII in hemophilia A (HemA) mice and dogs. The extension of rFVIIIFc half-life requires interaction of Fc with the neonatal Fc receptor (FcRn). In FcRn knockout mice, the extension of rFVIIIFc half-life is abrogated, and is restored in human FcRn transgenic mice. The Fc fusion has no impact on FVIII-specific activity. rFVIIIFc has comparable acute efficacy as rFVIII in treating tail clip injury in HemA mice, and fully corrects whole blood clotting time (WBCT) in HemA dogs immediately after dosing. Furthermore, consistent with prolonged half-life, rFVIIIFc shows 2-fold longer prophylactic efficacy in protecting HemA mice from tail vein transection bleeding induced 24-48 hours after dosing. In HemA dogs, rFVIIIFc also sustains partial correction of WBCT 1.5- to 2-fold longer than rFVIII. rFVIIIFc was well tolerated in both species. Thus, the rescue of FVIII by Fc fusion to provide prolonged protection presents a novel pathway for FVIII catabolism, and warrants further investigation.