Pharmacokinetic and thrombolytic properties of chimeric plasminogen activators consisting of a single-chain Fv fragment of a fibrin-specific antibody fused to single-chain urokinase

Blood. 1993 Feb 1;81(3):696-703.


The pharmacokinetic and thrombolytic properties were determined of two recombinant single-chain chimeric plasminogen activators (PA) consisting of u-PA-33k, a low-molecular weight derivative of single-chain urokinase-type PA (scu-PA) comprising amino acids Ala132 through Leu411, and of either a single-chain variable region fragment (Fv) derived from the fibrin fragment D-dimer-specific monoclonal antibody MA-15C5 (K12G0S32) or of the deglycosylated single-chain Fv fragment obtained by substitution of Asn88 with Glu (K12G2S32). Following bolus injection in hamsters, clearances of recombinant scu-PA (rscu-PA) and of K12G0S32 were similar. In contrast, clearance of K12G2S32 was fourfold slower than that of rscu-PA. The thrombolytic potency (percent lysis per u-PA administered in milligrams per kilogram body weight) and specific thrombolytic activity (percent lysis per microgram per milliliter steady-state plasma u-PA antigen level) of these compounds were studied in hamsters with an experimental pulmonary embolus consisting of a human plasma clot injected via the jugular vein. The doses of K12G0S32 and K12G2S32 required to obtain maximal rate of clot lysis were sixfold and 11-fold lower than that of rscu-PA. The steady-state u-PA-related plasma antigen levels of K12G0S32 and K12G2S32 required to obtain maximal rate of clot lysis were 10-fold and fourfold lower than that of rscu-PA. Thus, targeting of K12G0S32 to the clot surface by means of its glycosylated Fv fragment results in a 10-fold increase of its specific thrombolytic activity and sixfold increase of its thrombolytic potency as compared with those of rscu-PA. Targeting of K12G2S32 to the clot surface by means of its deglycosylated Fv fragment results in only a twofold increase of its thrombolytic activity. However, its fourfold slower clearance, combined with its twofold higher specific thrombolytic activity, results in an 11-fold increase of its thrombolytic potency over that of rscu-PA. These findings indicate that the thrombolytic potency of chimeric antibody-targeted PA may be increased by increasing the specific thrombolytic activity, reducing the clearance, or both.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Monoclonal / metabolism
  • Antibodies, Monoclonal / therapeutic use
  • Base Sequence
  • Cell Line
  • Cricetinae
  • DNA / genetics
  • DNA / isolation & purification
  • Fibrin / immunology*
  • Fibrinolytic Agents / pharmacokinetics*
  • Fibrinolytic Agents / therapeutic use*
  • Humans
  • Insecta
  • Macromolecular Substances
  • Molecular Sequence Data
  • Molecular Weight
  • Mutagenesis, Site-Directed
  • Oligodeoxyribonucleotides
  • Pulmonary Embolism / drug therapy*
  • Rabbits
  • Recombinant Fusion Proteins / pharmacokinetics*
  • Recombinant Fusion Proteins / therapeutic use*
  • Recombinant Proteins / pharmacokinetics
  • Recombinant Proteins / therapeutic use
  • Urokinase-Type Plasminogen Activator / genetics
  • Urokinase-Type Plasminogen Activator / pharmacokinetics*
  • Urokinase-Type Plasminogen Activator / pharmacology*


  • Antibodies, Monoclonal
  • Fibrinolytic Agents
  • Macromolecular Substances
  • Oligodeoxyribonucleotides
  • Recombinant Fusion Proteins
  • Recombinant Proteins
  • Fibrin
  • DNA
  • Urokinase-Type Plasminogen Activator