Mudi Misgav

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, t1/2, AUC and Cl), and the secondary endpoints (AUClast and Cmax) 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.

Safety and efficacy of turoctocog alfa (NovoEight®) during surgery in patients with haemophilia A: results from the multinational guardian™ clinical trials

Recombinant factor VIII (rFVIII) products provide a safe and efficacious replacement therapy for prevention and treatment of bleeding episodes in patients with haemophilia A. The present investigations from the multinational, open‐label guardian™ clinical trials assessed the haemostatic response of turoctocog alfa (NovoEight®), a rFVIII product, in patients with severe haemophilia A (FVIII ≤ 1%) undergoing surgery. All patients had a minimum of 50 exposure days to any FVIII product prior to surgery and no history of inhibitors. A total of 41 procedures (13 orthopaedic, 19 dental and 9 general) were performed in 33 patients aged 4–59 years. Of the 41 procedures, 15 were major surgeries in 13 patients and 26 were minor surgeries in 21 patients. The success rate for haemostatic response was 100% (success was defined as ‘excellent’ or ‘good’ haemostatic outcome). Turoctocog alfa consumption on the day of surgery ranged from 27 to 153 IU kg−1. The mean daily dose declined over time, while retaining adequate FVIII coverage as measured by trough levels. Overall, no safety issues were identified. No thrombotic events were observed and none of the patients developed FVIII inhibitors. In conclusion, the present results show that turoctocog alfa was effective in controlling blood loss by obtaining a sufficient haemostatic response in patients with severe haemophilia A undergoing surgery.

Differential roles of fibrinogen and von Willebrand factor on clot formation and platelet adhesion in reconstituted and immune thrombocytopenia.

BACKGROUND: Bleeding tendencies in immune thrombocytopenia (ITP) do not always correlate with the number of platelets, suggesting platelet function variation. We used a model of normal whole blood thrombocytopenia to compare platelet function and other hemostatic variables with ITP patients. We further investigated the effect of in vitro spiking with von Willebrand factor (vWF) and fibrinogen on platelet function and hemostatic variables. METHODS: The Cone and Plate(let) Analyzer was used to measure platelet adhesion (surface coverage [SC], %) and aggregation (average size, &mgr;m2) under defined shear rate (1200 s−1). Rotational thromboelastometry was used to determine variables of clot formation triggered by CaCl2 and tissue factor. RESULTS: In both the model of thrombocytopenia as well as in ITP, the SC and to some extent the average size were correlated to the platelet number over a range of 5 to 80 × 106/mL. The results obtained for most ITP samples were within the boundaries of the lower and upper limits set by the whole blood model of thrombocytopenia. The addition of 2 U/mL vWF (Haemate-P) to whole blood (calculated to plasma volume) results in an increase in the SC and average size without affecting clot formation. Spiking with fibrinogen (100 and 300 mg/dL) did not affect platelet deposition but improved clot formation. CONCLUSIONS: Using a model of whole blood thrombocytopenia enables us to establish reference variables for the Cone and Plate(let) Analyzer and rotational thromboelastometry and to assess platelet function and clot formation in the presence of severe thrombocytopenia. We demonstrated that in most cases of ITP, platelet function is comparable to normal platelets. This work also suggests that vWF and fibrinogen differentially affect primary and secondary hemostasis and therefore both may perform a function in the bleeding phenotype and possibly may be considered for treatment in patients with ITP.

The in vivo effect of fibrinogen and factor XIII on clot formation and fibrinolysis in Glanzmann's thrombasthenia

Glanzmanns thrombasthenia (GT) is characterized by increased bleeding risk. The treatment options in GT are limited. The aim of this study was to test the effect of GT blood supplementation with fibrinogen and factor XIII on thrombin generation, blood clotting, and fibrinolysis. Whole blood samples of GT patients and normal donors treated with eptifibatide (GT model) were subjected to clotting by CaCl2 and tissue factor. Thrombin generation was measured in platelet-rich plasma. Clot formation and tPA-induced fibrinolysis were evaluated in whole blood by rotation thromboelastometry (ROTEM). Blood was supplemented with fibrinogen (3 g/L) and/or FXIII (2 IU/mL). Thrombin generation analysis of blood derived from GT model and GT patients revealed decreased endogenous thrombin potential and peak height and extended lag time compared to control. However, this method was not sensitive to blood spiking with fibrinogen and FXIII. ROTEM revealed lower maximum clot firmness (MCF) and area under curve (AUC) in the blood of GT model and GT patients. In the absence of exogenous tPA, blood spiking with fibrinogen markedly enhanced clot quality while FXIII had no effect. Combination of fibrinogen and FXIII did not add to the effect of fibrinogen. In contrast, by the addition of tPA, both fibrinogen and FXIII separately and, to more extent, in combination enhanced clot quality as well as resistance against tPA-induced fibrinolysis (increasing MCF, AUC, and lysis onset time). In conclusion, fibrinogen and FXIII exerted stimulation of blood clotting and inhibition of fibrinolysis. Treating normal blood with eptifibatide mimics the changes of coagulopathy in GT blood.

Long-term patterns of safety and efficacy of bleeding prophylaxis with turoctocog alfa (NovoEight(®) ) in previously treated patients with severe haemophilia A: interim results of the guardian(™) 2 extension trial.

M. OZELO,* M. MISGAV,† F. ABDUL KARIM,‡ S. R. LENTZ,§ M. MARTIN-SALCES,¶ I . MATYTSINA,** T. SAUGSTRUP** and E. SANTAGOSTINO†† *IHTC ‘Claudio L.P. Correa’, INCT do Sangue Hemocentro UNICAMP, University of Campinas, Sao Paulo, Brazil; †National Hemophilia Center, Chaim Sheba Medical Center, Tel Aviv University, Tel Aviv, Israel; ‡National Blood Centre, Kuala Lumpur, Malaysia; §The University of Iowa Carver College of Medicine, Iowa City, IA, USA; ¶Haematology Department, Hospital Universitario La Paz, Madrid, Spain; **Novo Nordisk A/S, Soeborg, Denmark; and ††Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Maggiore Hospital Policlinico, Milan, Italy

Chitosan-based dressing for the treatment of external/accessible bleedings in children with bleeding tendency.

Introduction: Bleeding episodes in patients with congenital or acquired bleeding disorders are usually managed with factor concentrates or blood products. However, external and accessible bleeds may effectively be managed with topical hemostasis. Materials and Methods: After the application of the Hemcon, a Food and Drug Administration-approved chitosan-based hemostatic dressing was used as the “last resort” to successfully control external bleeds in 2 patients with severe bleeding disorders. We describe a single-center experience with this dressing, including its use in pediatric patients as the first mode of therapy. Results: A total of 5 patients (median age 2 y) with severe bleeding disorders were treated with topical chitosan-based dressing for a total of 6 bleeding episodes. The dressing was used either after the failure of extensive systemic therapy or as the first choice of treatment. In 4 of the 6 episodes, bleeding ceased immediately alleviating the need for systemic therapy. There was no rebleeding after the removal of the dressing and no adverse events or local skin reactions were recorded. Conclusion: Hemostatic dressings, such as the chitosan, should be encouraged for the treatment of external/accessible bleeds, especially among the pediatric patients with bleeding tendency.

The hemostatic efficacy of chitosan-pads in hemodialysis patients with significant bleeding tendency

Background Patients on chronic hemodialysis often have acquired coagulopathy that can aggravate bleeding from puncture site after needle extraction. Chitosan-based pads have been reported to accelerate hemostasis even in the presence of coagulopathy. The aim of this study was to evaluate the hemostatic efficacy of the chitosan pads compared to gauze pads, applied for local hemostasis. Methods A crossover study in a cohort of patients on hemodialysis with extended time to hemostasis after needle extraction. At the end of each dialysis, either gauze or chitosan pad was applied on both access points (arterial and venous). The type of pad was changed in the next dialysis all together 5 times in each patient (10 applications per patient for every pad). Results A total of 288 applications, 144 for each type of pad, were performed in 15 patients. The average time to hemostasis for the entire group was significantly shorter with the chitosan pads compared to the regular gauze pads (“arterial” point 3 vs. 18.5 min, p<0.001 “venous” access 2.8 vs. 13.2 min, p<0.001, respectively). Conclusions Chitosan pads significantly reduce time to hemostasis and should be considered for the treatment of accessible bleeds in patients with coagulopathy.

Thromboelastography during coronary artery bypass grafting surgery of severe hemophilia A patient - the effect of heparin and protamine on factor Viii activity.

&NA; Coronary artery bypass grafting surgery (CABG) in hemophilia patients is challenging. Thromboelastography (TEG) is useful to assess hemostasis perioperatively. A patient with severe hemophilia A underwent CABG with TEG studies. After factor VIII (FVIII) bolus dose, TEG was normalized. Following ‘on-pump’ heparinization, protamine administration revealed prolonged TEG-R and TEG-R with heparinase confirming it, whereas the activated clotting time was normal, suggesting low FVIII activity rather than excess of heparin. Another FVIII bolus yielded complete normalization of all TEG parameters. Data are compatible with in-vitro assays performed in our laboratory, showing that both heparin and protamine may impair measurable FVIII activity. The rational use of TEG measurements enabled more accurate hemostatic therapy application with regard to FVIII, heparin and protamine administration. Adopting this approach may lead to a better therapy tailoring for hemophilia patients undergoing CABG surgery.