Recombinant Factor VIIa Combined with Plasma Factor XIII Stabilize Clot Formation and Increase Clot Stability in Whole Blood from Patients with Severe Hemophilia A.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1039-1039 ◽  
Author(s):  
Benny Sorensen ◽  
Rasmus Rojkjaer ◽  
Jorgen Ingerslev
Keyword(s):  
Whole Blood ◽  
Factor Xiii ◽  
Hemophilia A ◽  
Recombinant Factor Viia ◽  
Factor Viia ◽  
Ex Vivo ◽  
Clot Formation ◽  
Severe Hemophilia ◽  
Clot Strength ◽  
Clot Stability

Abstract Patients with severe hemophlia A and inhibitors suffer from significantly compromised clot formation as well as reduced clot stability. Recombinant factor VIIa (rFVIIa - NovoSeven®, Novo Nordisk, Bagsvaerd, Denmark) has proven safe and efficacious for securing haemostasis in hemophilia patients with inhibitors. Recently, it was proposed that the reduced thrombin generation in severe haemophilia hinders sufficient activation of factor XIII and thereby result in insufficient covalent lateralization of fibrin (Blood2005; 106: 11, Abstract 321). The present study aimed at exploring the effect of rFVIIa and rFVIIa + plasma-derived FXIII (Haematological Technologies Inc) on whole blood clot (WB) formation and WB clot stability in severe hemophilia A. In total, 14 patients with a verified FVIII:C < 0.01 IU/ml were enrolled. Ex vivo studies were performed with rFVIIa (2 μg/ml), rFVIIa+FXIII (2+10 μg/ml), and a buffer control. Dynamic WB coagulation profiles describing initiation (clotting time=CT[sec]), propagation (maximum velocity=MaxVel [mm*100/sec]) and clot strength (maximum clot firmness=MCF[mm*100]) were recorded using thrombelastography and activation with a minute amount of tissue factor (TF, Innovin, final dilution 1:50000). WB clot stability was evaluated using a reaction mixture containing TF and tPA (1nM), followed by evaluation of the MCF and the total area under the elasticity curve after 120 min analysis time (AUEC[mm*100*sec]). Data are presented as mean and Wilcoxon statistical results. In the absence of tPA, Both rFVIIa+FXIII and rFVIIa significantly shortened the CT (Buffer=1424, rFVIIa+FXIII=739 (p=0.010), rFVIIa=881, (p=0.0005)) and accelerated WB MaxVel (Buffer=3.8, rFVIIa+FXIII=10.5 (p=0.0001), rFVIIa=9.2, (p=0.0002)). The standard deviation (SD) of the CT was significant lower in WB spiked with rFVIIa+FXIII than rFVIIa (Buffer SD=697, rFVIIa+FXIII SD=289 vs rFVIIa SD=655, p=0.007). In the absence of tPA, rFVIIa+FXIII increased the MCF significantly more than rFVIIa (Buffer=4441, rFVIIa+FXIII=6414 vs rFVIIa=5943, p=0.04) and the SD of the MCF was significant lower in WB spiked with rFVIIa+FXIII than rFVIIa (Buffer SD=2174, rFVIIa+FXIII SD=331 vs rFVIIa SD=948, p=0.0006). In the presence of tPA, rFVIIa+FXIII induced higher clot strength and stability than rFVIIa alone (MCF: Buffer=1313, rFVIIa+FXIII=3295 vs rFVIIa=3023, p=0.10 (N.S.); AUEC: Buffer=3.8*106, rFVIIa+FXIII=12.8*106 vs rFVIIa=10.2*106, p=0.0269). In conclusion, both rFVIIa (2μg/mL) and FXIII (10 μg/ml) added to rFVIIa (2 μg/ml), significantly increased WB clot formation and stability in this ex vivo evaluation of the clotting potential of WB from patients with severe hemophilia A.

Tranexamic Acid Increases Clot Stability in Patients with Severe Hemophilia A.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1023-1023
Author(s):  
Anne-Mette Hvas ◽  
Hanne Thykjaer Sorensen ◽  
Lisbeth Norengaard Sorensen ◽  
Kirsten Christiansen ◽  
Jorgen Ingerslev ◽  
...  
Keyword(s):  
Tranexamic Acid ◽  
Factor Viii ◽  
Blood Sample ◽  
Whole Blood ◽  
Hemophilia A ◽  
Ex Vivo ◽  
Maximum Velocity ◽  
Clot Formation ◽  
Severe Hemophilia ◽  
Clot Stability

Abstract Patients with severe Hemophilia A have a compromised clot formation. In addition, it is suggested that severe Hemophilia A is associated with reduced clot stability. Hence, during the recent years antifibrinolytics have been increasingly used as part of the prophylactic haemostatic treatment e.g. during surgical procedures. However, so far only limited evidence supports the systematic use of antifibrinolytics in these patients. In the present laboratory and clinical study we examined whether reduced clot stability in severe Hemophilia A could be improved by treatment with the antifibrinolytic drug tranexamic acid in combination with recombinant factor VIII (rFVIII). Eight patients with verified severe Hemophilia A (factor VIII:C <0.01 IU/mL) were included. None of the patients had previous or present inhibitor against factor VIII (Bethesda titre < 0.6 IU/mL), and all patients were abstinent to factor VIII substitution for at least 72 hours prior to blood sampling. A baseline blood sample was obtained. Subsequently, the patients received an i.v. bolus injection of rFVIII aiming at increasing the functional level of factor VIII to around 50%. Ten minutes later a second blood sample was obtained followed by i.v. injection of tranexamic acid (10 mg per kg). After another 10 minutes the third blood sample was obtained. In order to provide documentation on the haemostatic potential of tranexamic acid we adopted a thrombelastographic model of continuous whole blood coagulation using ROTEM Coagulation Analyzers (Pentapharm®, Munich, Germany). The whole blood clot formation was evaluated using activation with recombinant human tissue factor (TF - Innovin®, Dade Behring, final dilution 1:17000). The clot stability was evaluated using reaction mixture containing TF (final dilution 1:17000) and recombinant single chain tissue plasminogen activator (t-PA - American Diagnostics, final concentration t-PA 2 nM). Using the software DyCoDerivAn™ GOLD (AvordusoL, Risskov, Denmark) we obtained dynamic parameters of clot initiation (CT, s) and clot propagation such as the maximum velocity of clot formation (MaxVel, mm × 100/s) and the time until maximum velocity of clot propagation (t, MaxVel, s). Whole blood clot stability was analysed by evaluation of the maximum clot formation (MCF, mm × 100) and by the area under the elasticity curve (AUEC, mm × 100/s). Initially, ex vivo experiments were performed with buffer to record a baseline profile. Subsequently, rFVIII (final plasma concentration 0.5 IU/mL) and tranexamic acid (final plasma concentration 0.2 mg/mL) were added. Following the ex vivo experiments, analyses were performed 10 minutes after the patients had been administered rFVIII and tranexamic acid, respectively. We found almost total accordance between ex vivo and in vivo results both in the TF assay and the TF + t-PA assay. As expected, rFVIII increased clot formation indicated by a significantly shorter CT, higher MaxVel and shorter t, MaxVel. Tranexamic acid induced no further measurable improvements of the clot formation profile. Analyses of the clot stability using the TF + t-PA assay showed that rFVIII increased MCF three fold, whereas adding tranexamic acid revealed a four fold increase. The AUEC increased 5 fold after rFVIII and 24 fold after addition of tranexamic acid. In conclusion the study documents that treatment with tranexamic acid in combination with rFVIII significantly improves clot stability in patients with Hemophilia A.

Melagatran and Dynamic Whole Blood Clot Formation - Haemostatic Response to Ex Vivo Recombinant Factor Viia and Activated Prothrombin Complex Concentrate.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1857-1857 ◽  
Author(s):  
Benny Sorensen ◽  
Margareta Elg ◽  
Stefan Carlsson ◽  
Jorgen Ingerslev
Keyword(s):  
Whole Blood ◽  
Prothrombin Complex Concentrate ◽  
Recombinant Factor Viia ◽  
Factor Viia ◽  
Ex Vivo ◽  
Maximum Velocity ◽  
Clot Formation ◽  
Bleeding Complications ◽  
Activated Prothrombin Complex Concentrate ◽  
Healthy Males

Abstract The direct thrombin inhibitor melagatran (Exanta™, Astra Zeneca, Sweden) has proven efficient for the prevention and treatment of thromboembolism. Major bleeding complications are rare and may often be managed by discontinuation of the drug; however, in some cases of acute serious bleeding, an effective and instant haemostatic intervention may be needed. Potential haemostatic agents may include recombinant factor VIIa (rFVIIa - NovoSeven®, Novo Nordisk, Denmark) or activated prothrombin complex concentrate (APCC - Feiba®, Baxter, Austria). We hypothesized that melagatran induces abnormal whole blood (WB) clotting profiles and rFVIIa as well as APCC may improve the deteriorated clotting profiles. This study aimed to investigate the effect of ex vivo addition of melagatran to WB from healthy males and explore the haemostatic potential of rFVIIa and APCC. Following informed consent, 15 healthy males with an average age of 34 years were enrolled for blood sampling. Continuous WB coagulation profiles were recorded by ROTEG® thrombelastography employing activation with minute amounts of tissue factor (Innovin® final dilution 1:17,000 ~0.35pM). The initiation phase of WB clot formation was defined by the clotting time (CT - sec). Coagulation raw data were processed to provide dynamic parameters that concur with the propagation of WB coagulation such as maximum velocity (MaxVel - mm*100/sec) and time to maximum velocity (t, MaxVel - sec). Titration experiments (n=10) with ex vivo addition of melagatran to WB corresponding plasma concentrations ranging from 0 to 5.0 μM (12 steps) showed a significant and dose dependent prolongation of the CT and t, MaxVel. The MaxVel of WB clot formation was initially reduced from average 13.8 mm*100/sec (12.2-15.4, 95 % CI) to a plateau level of average 9.6 (7.5–12.2) at concentrations of melagatran ranging from 0.125 μM to 0.50 μM. A further and progressive decline in MaxVel was observed at concentrations of melagatran exceeding 1.0μM. Intervention studies (n=10) were performed ex vivo on WB spiked with melagatran at 0.25, 0.50, 1.0, and 2.0 μM followed by ex vivo addition of rFVIIa at concentrations of 25, 50, 100, and 200 nM or APCC at concentration of 0.5, 1.0, 2.0, and 4.0 U/mL. In all tested concentrations of melagatran, rFVIIa significantly shortened the CT and t, MaxVel, while the reduced MaxVel was not accelerated. No dose-response effect of rFVIIa was detected. In contrast, at all concentration of melagatran, APCC significantly and dose dependently shortened the CT, the t, MaxVel as well as increased the MaxVel. As compared to rFVIIa, the effect of APCC was statistically more potent. At melagatran 0.25 μM, APCC at 1.0, 2.0, and 4.0 U/mL normalized the MaxVel. In all other experimental settings, rFVIIa or APCC did not normalize the dynamic WB coagulation parameters following anticoagulation with melagatran. In conclusion, melagatran induces unique changes of dynamic WB clot formation as illustrated by the prolonged initiation and plateau interval of MaxVel in clot propagation. rFVIIa as well as APCC significantly improved the WB clot formation, although reversal of melagatran anticoagulation was not obtained. The more pronounced effect of APCC may be caused by addition of prothrombin and activated coagulation factors. However, this intervention may be less safe than use of rFVIIa.

Inhibition of fibrinolysis by recombinant factor VIIa in plasma from patients with severe hemophilia A

Blood ◽  
2002 ◽  
Vol 99 (1) ◽  
pp. 175-179 ◽  
Author(s):  
Ton Lisman ◽  
Laurent O. Mosnier ◽  
Thierry Lambert ◽  
Evelien P. Mauser-Bunschoten ◽  
Joost C. M. Meijers ◽  
...  
Keyword(s):  
Hemophilia A ◽  
Recombinant Factor Viia ◽  
Factor Viia ◽  
In Vitro Study ◽  
Clot Lysis ◽  
Severe Hemophilia ◽  
Large Variability ◽  
Lysis Time ◽  
Clot Lysis Time

Recombinant factor VIIa (rFVIIa) is a novel prohemostatic drug for patients with hemophilia who have developed inhibitory antibodies. The postulation has been made that hemophilia is not only a disorder of coagulation, but that hyperfibrinolysis due to a defective activation of thrombin activatable fibrinolysis inhibitor (TAFI) might also play a role. In this in vitro study, the potential of rFVIIa to down-regulate fibrinolysis via activation of TAFI was investigated. rFVIIa was able to prolong clot lysis time in plasmas from 17 patients with severe hemophilia A. The prolongation of clot lysis time by rFVIIa was completely abolished by addition of an inhibitor of activated TAFI. The concentration of rFVIIa required for half maximal prolongation of clot lysis time (Clys½-VIIa) varied widely between patients (median, 73.0 U/mL; range, 10.8-250 U/mL). The concentration of rFVIIa required for half maximal reduction of clotting time (Cclot½-VIIa) was approximately 10-fold lower than the Clys½-VIIa value (median, 8.4 U/mL; range, 1.7-22.5 U/mL). Inhibition of TFPI with a polyclonal antibody significantly decreased Clys½-VIIa values (median, 2.6 U/mL; range, 0-86.9 U/mL), whereas Cclot½-VIIa values did not change (median, 7.2 U/mL; range, 2.2-22.5 U/mL). On addition of 100 ng/mL recombinant full-length TFPI, a nonsignificant increase of Clys½-VIIa values was observed (median, 119.2 U/mL; range, 12.3-375.0 U/mL), whereas Cclot½-VIIa values did not change (median, 8.8 U/mL; range, 2.6-34.6 U/mL). In conclusion, this study shows that rFVIIa both accelerates clot formation and inhibits fibrinolysis by activation of TAFI in factor VIII-deficient plasma. However, a large variability in antifibrinolytic potential of rFVIIa exists between patients.

Risk of Bleeding and Inhibitor Development After Circumcision in Minimally Treated Severe Hemophilia A Patients: A One Year Prospective Study,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4653-4653
Author(s):  
Mohsen Saleh Elalfy ◽  
Nancy Samir Elbarbary ◽  
Mohamed Soliman Eldebeiky
Keyword(s):  
Single Dose ◽  
Factor Viii ◽  
Hemophilia A ◽  
Recombinant Factor Viia ◽  
Factor Viia ◽  
High Titer ◽  
Severe Hemophilia ◽  
Inhibitor Development ◽  
Factor Concentrate

Abstract Abstract 4653 Background Circumcision is a cultural practice for males in the Middle-East during first weeks of life. All parents of hemophilics are eager to do circumcision to their sibs, however, it may carry a risk for development of factor VIII inhibitors as well as risk of excessive bleeding. Objective To evaluate post-circumcision bleeding and assess incidence and time of inhibitor development over 12 months follow-up period of minimally treated severe hemophilia A patients. Patients and methods This prospective analysis has been conducted on eighteen minimally treated patients with severe hemophilia A (age range 8–36 months) with a median age of 18 months, who underwent circumcision during 2009 and twenty four age matched non circumcised patients minimally treated severe hemophilia A. Both groups were followed up for12 months from study entry and all were treated on demand therapy with a single plasma-derived factor VIII product. Hemophilic patients who underwent circumcision were inhibitor negative except two with low- titer inhibitor(3.3 and 4.4 BU/ml) respectively. One hour before the operation, intravenous tranexamic acid (25 mg/ kg) and first dose of factor concentrate (25 unit / Kg) were given to the patients. After reaching a trough plasma factor level more than 90%, patients underwent circumcision using general anesthesia and same surgical technique for all. Bolus injections of factor VIII concentrate were repeated in a dose of (25 units / Kg ) twenty four hours after operation. However, the two patients with inhibitors were given factor VIII concentrate in a dose of (50 units /Kg) with an extra dose at forty-eight hours. Another dose of factor concentrate (25 units/ Kg) was given just before removal of gauze dressing at 5th −7th day post operative. Follow up for inhibitor development was assessed every 8 exposure days (EDs) for 12 months or 100 EDs whichever comes first. Results: Of the eighteen patients enrolled, only one of the 2 patients with low- titer inhibitor had postoperative bleeding at day 5 and 7 respectively. First attack responded to a single dose of factor administration (50 units/Kg), whereas haemostasis was achieved in the second episode after a single dose of Recombinant Factor VIIa (90 microgram/kg) and applying absorbable haemostatic agent (gelatin sponge) and binding. None of the other patients had any bleeding or infection at site of surgery. High -titer inhibitors developed in three patients (16.6 % ) during the follow-up; after 8, 16 and 40 EDs respectively in contrast to four patients (16.6 %) developed high titer inhibitor in the non circumcised group; after a median of 16 exposure days (range 8– 60 EDs). Conclusion: Our study has shown that bleeding following circumcision was absent except in low- titer inhibitor patient necessitating administration of Recombinant Factor VIIa. Moreover, circumcision was not a risk for development of inhibitor where the incidence of high- titer inhibitors during12 months follow up was low in this cohort of minimally treated patients and comparable to non circumcised group. Disclosures: No relevant conflicts of interest to declare.

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