Direct thrombin inhibitors designed for improved safety/efficacy profile. Peptide inhibitors suitable for cost-effective recombinant production.Anti-thrombin peptides that can be fused to homing peptides for targeted delivery or fused to markers.

SUMMARY: Thrombosis, or pathogenic blood coagulation, is a major cause of death in Western societies. The current generations of antithrombotic agents have shortcomings which limit and complicate their clinical use. This technology relates to a series of new peptide inhibitors of thrombin designed to improve the efficacy and safety outcomes compared to present-day direct thrombin inhibitors (DTI). Made of only natural amino acids, these new anticoagulants will allow more cost-effective production through recombinant DNA technology. The mainstays of clinical anticoagulant treatments, although effective and widely used, have practical limitations such as poor specificity, unpredictable pharmacokinetics and undesirable bleeding complications. Novel bivalent peptide anticoagulants recognizing both free and clot-bound thrombin were obtained by connecting, through a flexible linker, a c- terminal fragment of hirudin to various structurally optimized tetra-peptide sequences. Rational design and combinatorial selection of the tetra-peptide moiety that recognizes the S- subsites of the thrombin active site (see Figure below) allowed for the production of new bivalent inhibitors exhibiting both antithrombin and anticoagulant activities yet interfering only partially with the catalytic active site of thrombin. These new molecules, obtained using only natural amino acids, promise to improve clinical safety/efficacy profiles compared with current generations of peptide DTIs. Thrombosis, or pathogenic blood coagulation, is a major cause of death in Western societies. The current generations of antithrombotic agents have shortcomings which limit and complicate their clinical use. This technology relates to a series of new peptide inhibitors of thrombin designed to improve the efficacy and safety outcomes compared to present-day direct thrombin inhibitors (DTI). Made of only natural amino acids, these new anticoagulants will allow more cost-effective production through recombinant DNA technology. CONCEPT: The mainstays of clinical anticoagulant treatments, although effective and widely used, have practical limitations such as poor specificity, unpredictable pharmacokinetics and undesirable bleeding complications. Novel bivalent peptide anticoagulants recognizing both free and clot-bound thrombin were obtained by connecting, through a flexible linker, a c- terminal fragment of hirudin to various structurally optimized tetra-peptide sequences. Rational design and combinatorial selection of the tetra-peptide moiety that recognizes the S- subsites of the thrombin active site (see Figure below) allowed for the production of new bivalent inhibitors exhibiting both antithrombin and anticoagulant activities yet interfering only partially with the catalytic active site of thrombin. These new molecules, obtained using only natural amino acids, promise to improve clinical safety/efficacy profiles compared with current generations of peptide DTIs. FEATURES AND BENEFITS: Potent anticoagulant activity - Rational design and combinatorial selection led to potent thrombin inhibition and strong anticlotting activities in the low nanomolar range (as low as 5 nM for IC50). High specificity for thrombin - These bivalent inhibitors, that are able to target both free and clot-bound thrombin, are highly selective because they exploit the synergistic binding of the inhibitors to both the active site (tetra-peptide moiety) and the fibrin recognition exosite of thrombin (c-terminal fragment of hirudin). Controlled balance between inhibition and cleavage - The amino acid composition of the tetra-peptide was varied in order to achieve a controlled balance between potent thrombin inhibition and peptide cleavage. Accordingly, decreased resistance of the peptide to cleavage by thrombin leads to transient inhibition of the active site and potential improvement of the safety profile by reducing systemic bleeding complications. Cost effective production - While current peptide DTIs such as Bivalirudin/AngiomaxTM contain an amino acid residue in the (d)-configuration and thus require the use of chemical synthesis, these new inhibitors composed of only genetically encodable amino acids, are suitable for cost-effective production through recombinant DNA techniques such as our patented fusion carrier technology (NRC no. 11391). Opportunities for gene therapy and other applications - The use of recombinant DNA technology for production of anti- thrombin peptides offers the possibility to deliver the inhibitors through gene therapy or improve their safety/efficacy by linking these molecules to homing peptides, markers or pharmacologically active peptides

Peptide inhibitors of thrombin as potent anticoagulants (NRC no. 11388). United States, Application number 60/371,714, Filed 2002-04- 12. United States, Application number 60/449,878, Filed 2003-02- 28. Patent Cooperation Treaty, Application number CA2004/000301, Filed 2004-02-27. Canada, Application number 2,515,798, Filed 2004-02-27. European Common Market, Application number 04715230.1 , Filed 2004-02-27

Licensing novel anticoagulant peptides.