title: A variant of recombinant factor VIIa with enhanced procoagulant and antifibrinolytic activities in an in vitro model of hemophilia.
abstract: OBJECTIVE
  Recombinant factor VIIa (rFVIIa, NovoSeven) has proven efficacy in treating bleeding in hemophilia patients with inhibitors. A rFVIIa analog with mutations V158D/E296V/M298Q (NN1731) exhibits increased procoagulant activity in in vitro and in vivo models. The aim of this work was to define the effects of NN1731 toward factor X activation, platelet activation, thrombin generation, and fibrin clot formation and stability.
  
  
  RESULTS
  In a cell-based in vitro model of hemophilia, rFVIIa and NN1731 similarly increased factor X activation on tissue factor-bearing cells; however, NN1731 exhibited 30-fold higher factor Xa generation on platelets than similar rFVIIa concentrations. NN1731-mediated thrombin generation depended on platelet activation, but NN1731 did not directly activate platelets. NN1731 produced 4- to 10-fold higher maximal thrombin generation rates than equal rFVIIa concentrations. Both rFVIIa and NN1731 shortened clotting times in the absence of factors IX and VIII; however, NN1731 did so at 50-fold lower concentrations than were required of rFVIIa. In fibrinolytic conditions, both rFVIIa and NN1731 increased fibrin formation and stability; however, NN1731 was effective at 50-fold lower concentrations than were required of rFVIIa.
  
  
  CONCLUSIONS
  By increasing factor Xa generation, NN1731 promotes the formation of thrombin and a stable clot to a greater degree than rFVIIa.
authors.affiliation: Department of Pediatrics, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Allen
authors.forename: Egon
authors.initials: E
authors.lastname: Persson
authors.forename: Robert A
authors.initials: RA
authors.lastname: Campbell
authors.forename: Mirella
authors.initials: M
authors.lastname: Ezban
authors.forename: Ulla
authors.initials: U
authors.lastname: Hedner
authors.forename: Alisa S
authors.initials: AS
authors.lastname: Wolberg
mesh_terms: D000933:Antifibrinolytic Agents / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D015942:Factor VIIa / Q000494:pharmacology*; D005170:Factor X / Q000378:metabolism*; D006467:Hemophilia A / Q000097:blood* / Q000188:drug therapy*; D006801:Humans; D066298:In Vitro Techniques; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000502:physiology; D015539:Platelet Activation / Q000187:drug effects*; D011994:Recombinant Proteins; D012680:Sensitivity and Specificity; D013917:Thrombin / Q000502:physiology
chemical_list: D000933:Antifibrinolytic Agents; D011994:Recombinant Proteins; D005170:Factor X; D015942:Factor VIIa; D013917:Thrombin