Recombinant agents for efficient and safe anticoagulation and thrombolysis

This project is based on the single-chain antibody (scFv) technology, an emerging class of biotechnologically produced therapeutics. ScFvs are designed to contain the variable regions of a full IgG antibody linked by a small linker. The sequence of scFvs can be encoded on a single plasmid and thus mutations and additional fusions of tags or effector molecules can be performed using molecular biology techniques. Our aim is the development of novel targeted thrombolytic drugs to treat thrombosis. We previously generated antibodies that specifically bind and block activated GPIIb/IIIa, the platelet receptor for fibrinogen. Its activation represents the final step common to all types of platelet activations. As this receptor's default state is a non-activated, resting state, GPIIb/IIIa needs to become activated in order to bind its major ligand, soluble fibrinogen causing platelet aggregation and thrombus formation. The anti-GPIIb/IIIa scFvs will be fused to a thrombolytic urokinase type plasminogen-activator and a third anticoagulation component (Factor Xa inhibition by tick anticoagulant peptide TAP), generating a new class of drugs with thrombolytic and anti-thrombotic properties in a single molecule. TAP is a highly potent and selective factor Xa inhibitor allowing effective anticoagulation because of its central, up-stream, and rate-determining position in the coagulation cascade. Targeting of TAP to clots can decrease systemic anticoagulation and thus bleeding complications. By accumulating the fibrinolytic drug at the site of the clot, our designed molecules have the potential to improve the efficacy and safety of the thrombolytic treatment by reducing the overall blood concentration and bleeding complications associated with current drugs. We expect a significant faster reopening of the occluded vessel in the animal model compared to non-targeted plasminogen activators.