Prophylactic therapy with Fibrogammin® P is associated with a decreased incidence of bleeding episodes: a retrospective study

Summary. Congenital factor XIII (FXIII) deficiency is an extremely rare, yet potentially life‐threatening, bleeding disorder, with a 30% rate of spontaneous intracranial haemorrhage. Routine prophylactic management is recommended for all individuals with clinically relevant (FXIII) deficiency and for all symptomatic individuals with congenital factor deficiency. Fibrogammin^® P is a purified, pasteurized concentrate of FXIII that appears to carry negligible risk of viral transmission, unlike other unprocessed products containing FXIII. An ongoing Phase II/III study of Fibrogammin^® P in patients with congenital FXIII deficiency is being conducted to evaluate the prophylactic efficacy and long‐term safety of this product. Using retrospective chart review data from subjects enrolled in the Phase II/III study, the current analysis was designed to compare spontaneous bleed‐event rates prior to and after the initiation of Fibrogammin^® P prophylaxis. Seven subjects were evaluable for comparison, having received no other prophylactic FXIII‐containing product during the 24 months prior to study entry. The mean annual number of spontaneous bleeds was 2.5 events per year prior to Fibrogammin^® P prophylaxis and 0.2 events per year during Fibrogammin^® P prophylaxis (P = 0.01). Patients reported no severe bleeds during Fibrogammin^® P therapy. This small sample supports a consistent and clinically meaningful reduction in spontaneous bleeding with prophylactic use of Fibrogammin^® P.     

Effects on fibrin network porosity of anticoagulants with different modes of action and reversal by activated coagulation factor concentrate

Orally available direct thrombin inhibitors (DTI) and direct activated factor X inhibitors (DFXaI) may replace vitamin K antagonists in patients needing long‐term anticoagulant treatment. We investigated the influence on the fibrin network of anticoagulants with different modes of action: AR‐H067637 (DTI), the active metabolite of AZD0837, apixaban (DFXaI), fondaparinux (indirect FXaI) and warfarin. Counteraction of the anticoagulant effect by FEIBA^® (Factor Eight Inhibitor Bypass Activity) was also investigated. Tissue factor, phospholipids and calcium were used to initiate coagulation in human platelet poor plasma. The permeability constant (Ks), reflecting the amount of buffer passing through the coagulum, was calculated and the fibrin network was visualized by 3D confocal microscopy. Warfarin (International Normalized Ratio 2‐3) increased Ks in plasma by 28–50% compared with control. ‘Therapeutic’ plasma concentrations of AR‐H067637 (0·3–0·6 μmol/l), apixaban (0·2–0·4 μmol/l) and fondaparinux (0·1–0·3 μmol/l) increased Ks by 72–91%, 58–76% and 36–53% respectively. Addition of FEIBA^® totally reversed the warfarin effect but only partially reversed effects of the other anticoagulants at concentrations that increased Ks by 50% or more. Fibrin network observed with 3D confocal microscopy agreed well with the permeability results. In conclusion, all examined anticoagulants rendered the fibrin network more porous. FEIBA^® reversed the increased permeability in warfarin plasma but had only partial effects on the other anticoagulants.     

Clinical efficacy in bleeding and surgery in von Willebrand patients treated with Fanhdi® a highly purified,doubly inactivated FVIII/VWF concentrate

Summary. Therapy with factor VIII/von Willebrand factor (FVIII/VWF) concentrate is the mainstay therapy in patients with von Willebrand disease (VWD) unresponsive to desmopressin. There are several commercially available FVIII/VWF concentrates that have been tested in VWD patients. We retrospectively analized the clinical efficacy in bleeding episodes and surgery of a highly purified FVIII/VWF complex with two inactivation steps (Fanhdi^®) in VWD patients. Sixty patients were included in the study. Treatment schedule consisted of one or more doses (standard dose 40 IU/kg body weight of FVIII) of Fanhdi^®. One hundred and fifty bleeding episodes were treated. These were: 28 serious bleedings; 92 moderate and 30 mild. An excellent clinical efficacy in almost 95% of cases was observed. Fanhdi^® was administered during 66 surgical procedures (38 major and 28 minor) with an overall efficacy of 98%. Fanhdi^® a highly purified, doubly virus‐inactivated FVIII/VWF concentrate, with a high content of active VWF and an excellent record of clinical safety, is a valid choice in treating VWD.     

Stabilization of fibrin clots by activated prothrombin complex concentrate and tranexamic acid in FVIII inhibitor plasma

Summary. Defective hemostasis in haemophilia patients with FVIII inhibitors results in a dramatic decrease in thrombin generation forming unstable fibrin clots that are susceptible to fibrinolyisis. In this study we tested whether the combination of plasma derived activated prothrombin complex concentrate (pd‐aPCC) with tranexamic acid (TXA) may improve fibrin clot stability in FVIII inhibitor plasma. A microplate assay for clot lysis time was used to assess clot stability in FVIII inhibitor plasma. The effect of pd‐aPCC on clot stability was first tested using the commercial FVIII inhibitor plasma. TXA (5 ～ 10 mg mL^?1) increased clot lysis time, but pd‐aPCC (0.25 ～ 1.0 U mL^?1) had no effect on it. The combination of pd‐aPCC and TXA significantly increased clot lysis time compared with TXA alone. The effect appeared to be limited to fibrin clot resistance to fibrinolysis, as TXA was found to have no effect on thrombin generation induced by pd‐aPCC. The effect of pd‐aPCC and TXA on clot stability was then tested and verified in plasma samples from ten patients with severe haemophilia A and inhibitors. The combination of TXA (10 mg mL^?1) and pd‐aPCC (0.5 U mL^?1) significantly increased clot lysis time compared to TXA alone. Our results suggest that the combination of pd‐aPCC with TXA improves clot stability in FVIII inhibitor plasma without additional increases in thrombin generation.     

A clinical study assessing the pharmacokinetics,efficacy and safety of AlphaNine®, a high‐purity factor IX concentrate,in patients with severe haemophilia B

Summary. Effective treatment with factor IX (FIX) requires a thorough consideration of the properties of the concentrate to be used as replacement therapy, to date, the only available treatment for haemophilia B. The aim of the study was to determine the pharmacokinetics, clinical efficacy and safety in routine clinical use of AlphaNine^®, a high‐purity human FIX concentrate. This open, single‐arm, multicentre, non‐randomized trial included 25 subjects (age ≥ 12) with moderate/severe haemophilia B. Pharmacokinetics was assessed at baseline and after a 6‐month follow‐up. The degree of haemostasis control achieved was evaluated during a 12‐month follow‐up. Safety was evaluated in terms of tolerance, thrombogenicity, immunogenicity and viral safety. Mean recovery was 1.01 ± 0.19 IU dL^?1 per IU kg^?1 at baseline and 1.23 ± 0.34 IU dL^?1 per IU kg^?1 6 months later. Terminal half‐life was 34.5 ± 6.2 h and 33.7 ± 5.4 h, respectively. Ratios of each parameter between the two pharmacokinetic studies were all close to 1. A total of 1,576,890 IU AlphaNine^® were administered in 889 infusions (mean dose per infusion: 1774 IU; 3.2 infusions per month per patient). The main reasons for infusion were mild/moderate bleeding (62.3%) and prophylaxis (20.5% continuous, 15.6% intermittent). Overall, 93.0% of the efficacy assessments were rated as excellent/good and 88.8% of bleedings resolved after the first infusion. Twenty‐one adverse events were reported in eight patients, none of which was considered related to the study medication. AlphaNine^® showed a pharmacokinetic profile in agreement with that of other plasma‐derived FIX concentrates and provides safe and clinically effective substitution therapy for patients with haemophilia B.     

Head‐to‐head comparison of the pharmacokinetic profiles of a high‐purity factor IX concentrate (AlphaNine®) and a recombinant factor IX (BeneFIX®) in patients with severe haemophilia B

Head‐on comparative studies of factor IX (FIX) concentrates performed under standardized conditions are rarely conducted regardless of being a valuable instrument guiding health care providers towards better informed and cost‐effective decisions. This study is an extension of a multicentre study that assessed the efficacy, safety and pharmacokinetics (PK) of AlphaNine^® in 25 previously treated patients with severe haemophilia B (FIX:C ≤ 2%). After a washout period ≥7 days following the last PK performed with AlphaNine^® after a dose of 65–75 IU kg^?1, an identical PK study was performed with BeneFIX^® on 22 of the same patients. Venous blood samples for analysis were taken at baseline and at 0.25, 0.5, 1, 3, 6, 9, 24, 48, 72 and 74 h post infusion. The outcomes of the comparison of the PK parameters were as follows: Mean (±SD) in vivo recovery (IVR) was 1.3 ± 0.4 IU dL^?1 per IU kg^?1 for AlphaNine^® and 1.0 ± 0.3 IU dL^?1 per IU kg^?1 for BeneFIX^® (P < 0.01). Mean terminal half‐life, mean residence time, area under the curve, clearance and volume of distribution of BeneFIX^® were 36.0 ± 12.8 h, 39.3 ± 13.9 h, 1631 ± 467 IU h dL^?1, 0.046 ± 0.01 dL kg^?1 min^?1 and 1.75 ± 0.52 mL kg^?1 respectively. These values were not significantly different to those observed in AlphaNine^®, although BeneFIX^® displayed higher than expected IVR values and lower than expected clearance values. In conclusion, AlphaNine^® showed a comparable half‐life, but an IVR significantly higher than that of BeneFIX^®. This dissimilarity may have implications on dosing requirements for on‐demand treatment regimes affecting optimal resource allocation.     

Clinical assessment of Optivate®, a high‐purity concentrate of factor VIII with von Willebrand factor,in the management of patients with haemophilia A

Summary. Factor VIII (FVIII) concentrates have revolutionized the treatment of patients with haemophilia A. Concerns over the transmission of viral infections through these products have been addressed through stringent, donor‐screening procedures and robust antiviral manufacturing steps. Bio Products Laboratory has developed a high‐purity FVIII product with von Willebrand factor, Optivate^®. Its safety, tolerability and efficacy as prophylaxis and treatment of bleeds have been established in long‐term studies. Seventy previously treated patients with severe haemophilia A, with ≥20 exposure days, were recruited into two long‐term, multicentre, open‐label studies. The protocols were virtually identical. Patients received Optivate^® either prophylactically or on‐demand. A mean of 159.0 EDs were experienced over 11 320 infusions. Under both conditions, Optivate^® was well tolerated. Only 10% of patients experienced a treatment‐related adverse event; the most commonly reported were headache (4% of patients) and dizziness (3% of patients). The mean number of bleeds/patient over the 2 year treatment period was 23.5 during prophylactic use and 70.4 during on‐demand use. In patients treated prophylactically, clinical responses to breakthrough bleeds were rated by physicians as excellent or good and as very helpful or helpful by patients in 95% of bleeds. Clinical responses for on‐demand patients were rated as excellent or good by physicians and helpful or very helpful by the patients for 91% of bleeds. There were no viral transmissions or inhibitors. The studies confirm the clinical efficacy and safety of Optivate^® in both prophylactic and on‐demand management of patients with haemophilia A.     

Use of Haemate® P as immune tolerance induction in patients with severe haemophilia A who failed previous induction attempts: a multicentre observational study

Immune tolerance induction (ITI) can eliminate factor VIII (FVIII) inhibitory antibodies that appear during FVIII replacement therapy. If first‐line ITI fails, switching to a different FVIII concentrate, especially one containing von Willebrand factor (VWF), has been advocated. The objective of the study was to assess the efficacy and safety of Haemate^® P, a plasma‐derived FVIII concentrate containing high levels of VWF, as ITI in severe haemophilia A patients who had failed at least one prior ITI attempt with a different FVIII concentrate. In this multicentre, observational study, Haemate^® P was administered at a starting dose of 83–308 IU kg^?1 day^?1 (1500–6000 IU day^?1). Efficacy was assessed by standard criteria (e.g. Bethesda titre, FVIII recovery and half‐life), and bleeding characteristics. Nine patients from six haemophilia centres were treated with Haemate^® P after failing one (n = 2), two (n = 5) or three (n = 2) prior ITI courses. The median time from inhibitor detection to Haemate^® P treatment was 5.4 years. The median Haemate^® P dose was 134 IU kg^?1, and the median treatment duration 32 months. During median of 47 months of follow‐up, complete response, partial response and treatment failure were observed in one, three and five patients respectively. Five patients experienced seven adverse events (AEs), including two serious AEs (sepsis). Haemate^® P was discontinued due to an AE in one patient with a partial response. Haemate^® P salvage ITI resulted in complete or partial tolerization in four of nine patients (44%) who had failed previous ITI attempts using different FVIII concentrates.     

Incidence and risk factors for inhibitor development in previously untreated severe haemophilia A patients born between 2005 and 2010

The objective of this study was to evaluate the inhibitor development (ID) in previously untreated patients (PUPs) with severe haemophilia A (FVIII ≤ 0.01 IU mL^?1). All Canadian Haemophilia Treatment Centres completed a questionnaire on patients born between September 2005 and August 2010 and followed for up to 7 years. Eligible patients had at least 20 exposure days (ED) or had developed an inhibitor. The odds ratio (OR) and 95% confidence intervals (95% CI) for risk factors to develop an inhibitor were estimated using unconditional logistic regression. A total of 99 haemophilia A PUPs were studied. Thirty‐four (34%) developed an inhibitor (24/34 of high titre). Inhibitors developed in 25/63 (40%) patients with a high‐risk mutation. ID was most frequent in Aboriginals (86%). Dose intensity (IU kg^?1 day^?1 X number of ED) at first exposure to factor VIII (FVIII) was associated with a crude OR increase of 1.10 (95% CI: 0.99–1.23) with each increase of 100 dose‐intensity units. Haemarthrosis and intracranial bleeding as the indication for first exposure to FVIII concentrate were associated with a crude OR for ID of 7.63 (95% CI: 2.14–27.17) and 5.08 (95% CI: 1.11–23.31) respectively. ID according to FVIII concentrate used was: Advate ^® 18/50 (36%), Kogenate FS^® or Helixate FS^® 15/36 (42%), Wilate^® 0/11 and Xyntha^® 1/2. In multivariate analysis, Aboriginal ethnicity (OR = 11.69; 95% CI: 1.11–122.86) and haemarthrosis (OR = 4.49; 95% CI: 1.08–18.61) were statistically significant. The cumulative incidence of ID in severe haemophilia A PUPs was 34% and varied according to ethnicity, type of bleeding at first ED, type of FVIII product and dose intensity at first exposure.     

An ultrapure plasma‐derived monoclonal antibody‐purified factor IX concentrate (Nonafact®), results of phase III and IV clinical studies

Summary. Nonafact^®, an ultrapure, monoclonal antibody‐purified factor IX concentrate (FIX) was developed to minimize risk of thrombotic complications and viral transmission. To investigate the pharmacokinetics, efficacy and safety, phase III/IV studies were performed in the Netherlands and Poland from 1996 to 2007. The mean half‐life, in vivo response and recovery of Nonafact^® were 18.7 (SD 2.0) h, 1.1 (SD 0.2) IU dL^?1 per IU kg^?1 b.w. of FIX infused and 49% (SD 10%), respectively. Eleven surgical procedures were performed in eight patients. During two surgeries, both high‐risk, blood loss was observed. No postoperative bleeding occurred. The in vivo recovery of FIX was higher than expected. In the phase III follow‐up study, 26 previously treated patients (PTP) were included with a median follow‐up of 1130 days. From the 1617 minor bleedings, 80.5% was stopped after a single infusion. In the phase IV study thirteen patients were treated for a median study period of 737 days. In the two follow‐up studies the investigators rated the effect of Nonafact^® as excellent/good in 95% of major bleedings. Surgeries for which Nonafact^® was given prophylactically were without bleeding problems. In total more than 10 million units of Nonafact^® were used during almost 120 person‐years. Only one minor adverse event was reported. No inhibitors, viral transmissions and thrombogenic events occurred. In conclusion, Nonafact^® is safe and provides excellent haemostasis in haemophilia B patients treated for spontaneous bleeding or undergoing surgical procedures. Due to the excellent in vivo recovery characteristic, treatment with Nonafact^® is cost saving compared to other FIX products.     

Pharmacokinetics of Optivate®, a high‐purity concentrate of factor VIII with von Willebrand factor,in patients with severe haemophilia A

Summary. Optivate^® is a high purity factor VIII/von Willebrand factor (FVIII/VWF) concentrate, which is manufactured using two antiviral processes: solvent/detergent and terminal dry heating (80°C for 72 h). A multicentre, non‐randomized open‐label study in 15 patients was conducted to test the pharmacokinetics (PK) of Optivate^®. PK variables were analysed for the patients’ prior FVIII product (PK1), their first dose of Optivate^® (PK2) and at 3 months therapy (PK3). Mean non‐compartmental half‐lives (h) were 14.1, 12.4 and 12.1, respectively (P = 0.45), mean clearances (mL h^?1 kg^?1) were 3.6, 3.2 and 3.1, respectively (P = 0.051), MRTs (h) were 19.0, 17.3 and 17.4, respectively (P = 0.39) and mean AUC_0–48h (h IU mL^?1) were 14.3, 15.4 and 16.6, respectively (P = 0.051) and mean AUC_0–∞ (h IU mL^?1) were 15.9, 16.4 and 17.9, respectively (P = 0.18). The recovery data from this PK study was aggregated with recovery data collected from another study, with similar design but devoid of the other PK measurements. A total of 309 recoveries were conducted in 70 patients. The overall mean recovery per subject across 27 Optivate^® batches was 2.7 IU dL^?1 per IU kg^?1. There were no clinical differences between Optivate^® and other FVIII products, and except for volume of distribution (Vd), no statistically significant differences were seen with respect to any of the other PK variables, or in recovery between weeks 0 and 12. Therefore, the PK of FVIII is not affected by the processes used to manufacture Optivate^®, which can be expected to be effective in the management of patients with haemophilia A.     

ADAMTS13 content in plasma‐derived factor VIII/von Willebrand factor concentrates

Thrombotic thrombocytopenic purpura (TTP) is a microangiopathy syndrome caused by a congenital or acquired deficiency of ADAMTS13, a plasma metalloprotease that cleaves von Willebrand factor (VWF) and thus prevents the formation of platelet‐rich thrombi in the microcirculation. TTP can be fatal if not appropriately and timely treated with the infusion of fresh frozen plasma (FFP) or exchange plasmapheresis, that reverse the process of microangiopathy by removing anti‐ADAMTS13 autoantibodies and replacing functional ADAMTS13. The treatment of TTP with FFP is not free from risks and must be administered in hospitals or clinics, owing to the substantial amount of plasma volume infused or exchanged and the frequent need of catheter application. Moreover, most FFPs are not subjected to treatments to remove or inactivate blood‐borne infectious agents. A number of recent reports indicate that certain plasma‐derived VWF‐factor VIII (FVIII) concentrates are clinically effective in the treatment of congenital TTP. In this study, we measured ADAMTS13 levels in various plasma‐derived VWF‐FVIII concentrates, showing that Koate^®‐DVI (Grifols), contained relatively high amounts of ADAMTS13 and that Alphanate^® (Grifols) was the closest other product in terms of protease content. Koate^®‐DVI contains, on average (five lots tested), 0.091 ± 0.007 Units of ADAMTS13 activity per IU of FVIII. On the basis of this analysis and other reports of VWF‐FVIII concentrate utilization in congenital TTP, potential dosing, and future clinical developments are discussed. Am. J. Hematol. 88:895–898, 2013. © 2013 Wiley Periodicals, Inc.     

Successful hip arthroplasty in an adult male with severe factor XI deficiency using Hemoleven®, a factor XI concentrate

Summary. Severe factor XI (sFXI) deficiency is a rare bleeding disorder (RBD). FXI replacement is most often required for surgical hemostasis. Plasma, the sole US treatment option, is often complicated by life‐threatening allergic reactions. In such circumstances, the FDA offers a mechanism for institution‐industry collaboration to facilitate limited use of replacement products licensed abroad. A 58 years old man with sFXI deficiency, required hip replacement. In the past, he received prophylactic plasma for thyroidectomy and experienced a severe allergic reaction. A single use institutional IND FDA application was initiated in collaboration with LFB (Les Ulis, France) to access Hemoleven^®, a plasma‐derived FXI concentrate. The application required an investigator‐initiated IRB‐approved protocol for treatment and safety/efficacy monitoring that included: preoperative thrombophilia, FXI inhibitor and pharmacokinetic (PK) evaluations; peri‐ postoperative administration of ≤ 4 doses of 10‐15 U/kg Hemoleven^®; DIC monitoring; postoperative thromboprophylaxis; observation for product efficacy and potential complications. PK study demonstrated the expected 1.8% FXI recovery per U/kg with half‐life of 62 hours. Mild D‐Dimer elevation was noted 6‐9 hours post‐infusion. The initial dose (15U/kg) was administered 15 hours before surgery; subsequently, 3 doses (10U/kg) were infused every 72 hours. Hemostasis was excellent. No complications were observed. Collaboration allowed for successful patient access to Hemoleven^® with excellent PK, safety, and efficacy. This case underscores the need for additional efforts to ensure safe and effective licensed replacement therapies for RBD patients.     

Evaluation of a universal point‐of‐issue assay for bacterial detection in buffy coat platelet components

Bacterial contamination of platelet concentrates poses a major post‐transfusion infectious risk. This study was aimed at evaluating the efficacy of the BacTx ^® assay (Immunetics Inc.) for bacterial detection in leucocyte‐reduced buffy coat platelet pools and for its sensitivity in detecting clinical isolates, including bacteria that form surface‐attached aggregates (biofilm positives). Platelet pools were inoculated at bacterial concentrations of 0·8–13 CFU/ml. The BacTx ^® assay detected all species at concentrations ≥10³ CFU/ml within 20–69 h of platelet incubation. Detection of slow‐growing and biofilm‐forming strains was delayed in comparison with the other strains. This assay could be used as a point‐of‐issue method to increase the safety of the platelet supply.     

An open clinical study assessing the efficacy and safety of Factor IX Grifols®, a high‐purity Factor IX concentrate,in patients with severe haemophilia B

Summary. Factor IX Grifols^® is a new high‐purity plasma‐derived FIX concentrate with two specific pathogen elimination steps. Until this study was performed, there were no detailed reports with an adequate number of patients on the clinical evaluation of this product. To determine the efficacy and safety of Factor IX Grifols^® for replacement therapy in previously treated patients with severe haemophilia B, this open, multicentre and non‐randomized study included 25 male subjects over the age of 12 with severe haemophilia B. Patients underwent prophylaxis and treatment of bleeding episodes with Factor IX Grifols^® for 1 year. The clinical efficacy and safety of this product were assessed. Forty percent of the patients were children and adolescents (12–17 years old). During the 12 months follow‐up, 1 446 000 IU of Factor IX Grifols^® were administered in 961 infusions (range 12–83 infusions per patient): 31% for prophylaxis and 69% for bleeding episodes. Only five major bleeding events were reported in two patients. These haemorrhages were successfully treated with a mean of 2900 IU per bleed (range 1500–4000 IU), and 1–3 infusions per bleed. The average time elapsed from the first infusion to resolution of bleeding was 43 h (median). Overall, haemostasis was rated as excellent or good by the investigator in 96% of the infusions. No product‐related adverse events were reported. Factor IX Grifols^® is an effective and safe Factor IX concentrate and can be considered as a first line option for replacement therapy in haemophilia B patients.     

Bioequivalence between two serum‐free recombinant factor VIII preparations (N8 and ADVATE®) – an open‐label,sequential dosing pharmacokinetic study in patients with severe haemophilia A

Summary. Recombinant coagulation factor VIII (rFVIII) concentrates provide a safe and efficacious replacement therapy for treatment and prevention of bleeding in patients with severe haemophilia A. The aim of this study was to compare the pharmacokinetic (PK) and safety profiles of two serum‐free rFVIII products: N8, a new rFVIII manufactured by Novo Nordisk and Advate^®, a marketed product. Patients with severe haemophilia A with >150 exposure days to FVIII, without current or past inhibitors, were enrolled in an open‐label, first human dose (FHD), multicentre trial. Twenty‐three patients first received a single dose of 50 IU kg^?1 body weight Advate^® followed by 50 IU kg^?1 body weight N8 at the next visit. A 4‐day washout period was required prior to each dosing. Blood samples for PK and safety analyses were drawn prior to dosing and at intervals up until 48 h postdosing. The PK parameters were based on FVIII clotting activity (FVIII:C) measurements. Occurrence of adverse events was closely monitored. The mean profiles of FVIII:C and all primary and secondary parameters for Advate^® and N8 were comparable. The 90% CI for the treatment ratio (Advate^®/N8) for all primary endpoints (incremental recovery, t_1/2, AUC and Cl), and the secondary endpoints (AUC_last and C_max) were within the bioequivalence interval of 0.8–1.25. There were no safety concerns in the study and no reports of inhibitor formation in the 72‐h period following exposure to a single N8 dose. In conclusion, N8 is bioequivalent to Advate^®. Furthermore, N8 is well tolerated in the FHD trial.     

A qualitative and quantitative analysis of von Willebrand factor contained in a very high-purity plasma-derived FVIII concentrate

Background and Objectives We studied the structural and functional properties of von Willebrand factor (VWF) molecules present in a very high‐purity plasma‐derived factor VIII concentrate (VHP pdFVIII – Factane^®) because several observations suggest that the presence of VWF in factor VIII (FVIII) preparations may decrease their immunogenicity. Materials and Methods Ten marketed batches of VHP pdFVIII (Factane^®) with levels of VWF ranging from 15 to 39 IU/100 IU FVIII were analysed. The VWF multimeric pattern was studied by agarose gel electrophoresis. The binding of VWF to FVIII was studied by gel filtration and ELISA. The binding of VWF to GPIb was analysed by ELISA. Results The results showed that high‐molecular‐weight multimers of VWF were present in VHP pdFVIII (Factane^®). VWF subunits maintain a triplet structure similar to that of normal plasma. Regardless of the VWF content, all FVIII molecules of each batch were co‐eluted with VWF, and no free FVIII was detectable. By immunoassays, VWF was found to be able to bind to FVIII and platelet GPIb in a similar manner to that of VWF in normal plasma. Conclusions In all the VHP pdFVIII (Factane^®) batches studied, regardless of the level of VWF, the structure and capacity of VWF binding to FVIII and to platelet GPIb were fully preserved.     

The PFA‐100® does not predict delta‐granule platelet storage pool deficiencies

Summary.  There are no published reports investigating the ability of the platelet function analyzer (PFA‐100^®) to detect the presence of delta‐granule platelet storage pool deficiencies (δ‐PSPD), a common mild bleeding disorder. Prior studies of the PFA‐100^® and congenital platelet disorders have been limited by small numbers of patients with a variety of disorders. We examined PFA‐100^® results in a large paediatric patient population diagnosed specifically with δ‐PSPD, and determined the relationship between PFA‐100^® and platelet electron microscopy (the gold standard for diagnosis). This study is a retrospective review of patients <19 years of age diagnosed with δ‐PSPD at Nationwide Children’s Hospital from 2008 to 2010. To examine the correlation between PFA‐100^® and average number of granules per platelet we used Spearman’s Rho as a non‐parametric measure of dependence. A total of 105 patients diagnosed with δ‐PSPD were included, of which 99 patients underwent PFA‐100^® testing. Of those tested 46% had at least one abnormal closure time, whereas 16% had abnormal results for both cartridges. We found no statistical correlation between C‐EPI closure time and average number of granules per platelet (ρ= ?0.0095, P‐value = 0.9328), nor between C‐ADP closure time and the average number of granules (ρ = 0.0315, P‐value = 0.7798). The PFA‐100^®, a widely used screening test for suspected bleeding disorders, did not correlate with presence or severity of δ‐PSPD as determined by platelet electron microscopy. When evaluating patients with suspected bleeding disorders, PFA‐100^® alone cannot be used to rule out the presence of a δ‐PSPD.     

Clinical observation on safety and efficacy of a plasma‐ and albumin‐free recombinant factor VIII for on‐demand treatment of Chinese patients with haemophilia A

Summary. Recombinant FVIII (rFVIII) has become the best choice for treating bleeding of haemophilia A patients. A plasma‐ and albumin‐free recombinant FVIII (rAHF‐PFM, ADVATE^®), as the third generation rFVIII, virtually eliminates the risk of blood‐borne disease transmission by excluding all human blood derived additives throughout cell culture, purification and formulation. In this multicentre prospective clinical study we evaluated the efficacy, safety and immunogenicity of ADVATE^® in Chinese patients with haemophilia A. Fifty‐eight patients enrolled and received ADVATE^® treatment. Of the patients enrolled, eight (13.79%) had severe haemophilia, 45 (77.59%) had moderate haemophilia and five (8.62%) had mild haemophilia. Fifty‐four patients completed 6 months of observation. A total of 781 bleeds occurred in these 58 subjects, all evaluable per‐protocol. A total of 984 infusions were administered with a mean of 17.0 ± 11.1 infusions per patient. On average, each patient received a mean of 15030.2 ± 7972.7 IU ADVATE^® (median 13 625 IU, range 9500–19 750 IU) during 6 months. The majority of bleeding episodes (95.9%) were successfully treated with one or two infusions of ADVATE^®. Overall, response to the first ADVATE^® treatment was rated as either ‘excellent’ (82.8%) or ‘improved’ (17.2%) in all subjects. All patients tolerated ADVATE^® infusions well. One patient (1/58, 1.7%) developed an inhibitor of 4 Betheseda units at day 180 visit. The results of this clinical observational study support that ADVATE^® is efficacious, safe and well tolerated in the treatment of Chinese patients with haemophilia A.