title: Drug-drug interaction of the anti-TFPI aptamer BAX499 and factor VIII: studies of spatial dynamics of fibrin clot formation in hemophilia A.
abstract: BACKGROUND
  In recent years, a number of tissue factor pathway inhibitor (TFPI) antagonists have been developed to serve as bypassing agents to improve hemostasis in hemophilia A. Since TFPI antagonists and FVIII concentrates are procoagulants, their combined effect on spatial clot formation could be potentially pro-thrombotic.
  
  
  OBJECTIVE
  To investigate the cooperative effect of TFPI inhibition and supplementation of FVIII in hemophilia A in a spatial, reaction-diffusion experiment in vitro.
  
  
  METHODS
  Plasma was collected at different time points from hemophilia A patients undergoing prophylaxis and was supplemented in vitro with TFPI inhibitor BAX499 (formerly ARC19499) at concentrations from 0 up to 600nM. Clotting propagation in recalcified plasma activated by a surface with immobilized tissue factor (TF) was monitored by videomicroscopy.
  
  
  RESULTS
  Increasing concentration of BAX499 improved coagulation for all hemophilia A plasma samples activated with TF at 1.6pmole/m(2) by shortening lag time and increasing initial clot growth velocity and clot size. In contrast, plasma concentration of FVIII had little effect on lag time, but increased spatial clot growth velocity. There was a decrease in the BAX499 efficiency as FVIII concentration increased (lag time shortened by 50% if FVIII:C<5%, but the effect was only 25% if FVIII:C>30%).
  
  
  CONCLUSIONS
  The results indicate that BAX499 has an effect on clotting in hemophilia A plasma at low FVIII concentrations, however has little effect at high FVIII concentrations.
authors.affiliation: Center for Theoretical Problems of Physicochemical Pharmacology, 4 Kosygina Street, Moscow 119991, Russia. Electronic address: parunov@gmail.com.
authors.forename: Leonid A
authors.initials: LA
authors.lastname: Parunov
authors.affiliation: National Research Center for Hematology, 4 Novyi Zykovskii Passage, Moscow 125167, Russia.
authors.forename: Natalia P
authors.initials: NP
authors.lastname: Soshitova
authors.affiliation: National Research Center for Hematology, 4 Novyi Zykovskii Passage, Moscow 125167, Russia.
authors.forename: Olga A
authors.initials: OA
authors.lastname: Fadeeva
authors.affiliation: Center for Theoretical Problems of Physicochemical Pharmacology, 4 Kosygina Street, Moscow 119991, Russia; National Research Center for Hematology, 4 Novyi Zykovskii Passage, Moscow 125167, Russia; Center of Pediatric Hematology, Oncology and Immunology, 1 Samora Mashely, Moscow , Russia.
authors.forename: Anna N
authors.initials: AN
authors.lastname: Balandina
authors.affiliation: National Research Center for Hematology, 4 Novyi Zykovskii Passage, Moscow 125167, Russia; Center of Pediatric Hematology, Oncology and Immunology, 1 Samora Mashely, Moscow , Russia.
authors.forename: Konstantin G
authors.initials: KG
authors.lastname: Kopylov
authors.affiliation: National Research Center for Hematology, 4 Novyi Zykovskii Passage, Moscow 125167, Russia; Center of Pediatric Hematology, Oncology and Immunology, 1 Samora Mashely, Moscow , Russia.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Kumskova
authors.affiliation: Archemix Corp., 148 Sidney Street, Cambridge, MA 02139, USA.
authors.forename: James C
authors.initials: JC
authors.lastname: Gilbert
authors.affiliation: Archemix Corp., 148 Sidney Street, Cambridge, MA 02139, USA.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Schaub
authors.affiliation: Baxter Healthcare Corporation, 148 Sidney Street, Cambridge, MA 02139 USA.
authors.forename: Kathleen E
authors.initials: KE
authors.lastname: McGinness
authors.affiliation: Center for Theoretical Problems of Physicochemical Pharmacology, 4 Kosygina Street, Moscow 119991, Russia; National Research Center for Hematology, 4 Novyi Zykovskii Passage, Moscow 125167, Russia; Center of Pediatric Hematology, Oncology and Immunology, 1 Samora Mashely, Moscow , Russia; Department of Physics, Moscow State University, 1 Vorobyevy Gory, Moscow 119991, Russia.
authors.forename: Fazoil I
authors.initials: FI
authors.lastname: Ataullakhanov
authors.affiliation: Center for Theoretical Problems of Physicochemical Pharmacology, 4 Kosygina Street, Moscow 119991, Russia; National Research Center for Hematology, 4 Novyi Zykovskii Passage, Moscow 125167, Russia; Center of Pediatric Hematology, Oncology and Immunology, 1 Samora Mashely, Moscow , Russia; Department of Physics, Moscow State University, 1 Vorobyevy Gory, Moscow 119991, Russia.
authors.forename: Mikhail A
authors.initials: MA
authors.lastname: Panteleev
mesh_terms: D052157:Aptamers, Nucleotide / Q000493:pharmacokinetics / Q000494:pharmacology*; D004347:Drug Interactions; D005169:Factor VIII / Q000493:pharmacokinetics / Q000494:pharmacology*; D005337:Fibrin / Q000378:metabolism*; D006467:Hemophilia A / Q000097:blood* / Q000188:drug therapy*; D006801:Humans; D008074:Lipoproteins / Q000037:antagonists & inhibitors
chemical_list: C577143:ARC19499; D052157:Aptamers, Nucleotide; D008074:Lipoproteins; C051928:lipoprotein-associated coagulation inhibitor; D005169:Factor VIII; D005337:Fibrin
keywords: BAX499; coagulation; drug-drug interaction; hemophilia A; spatial propagation