Pharmacokinetics and pharmacodynamics of BB-10153, a thrombin-activatable plasminogen, in healthy volunteers.

BB-10153 is an engineered variant of human plasminogen that is activated to plasmin by thrombin. Thrombus-selective induction of reperfusion and prevention of reocclusion have been demonstrated following bolus administration in animal models of thrombosis. The objective of the study was to examine the pharmacokinetics and pharmacodynamics of BB-10153 administered as an intravenous bolus to healthy male human volunteers. Cohorts of four were dosed with BB-10153 (n = 3) or placebo (n = 1). In total, placebo was received by eight volunteers and 0.08, 0.2, 0.6, 1.2, 1.8, 2.4, 3.6 and 4.8 mg kg(-1) BB-10153 by three volunteers each. There was a linear relationship between AUC/Cmax and dose. The half-life of BB-10153 was approximately 3-4 h and all the BB-10153 in the circulation retained the ability to be activated by thrombin. There was a dose-related increase in plasma fibrin D-dimers. Ex vivo plasma clot lysis was observed at doses of 3.6 and 4.8 mg kg(-1), whereas lysis of clots formed from euglobulin-fractionated plasma was first evident at 0.6 mg kg(-1) and activity increased with dose. This activity decreased with time in line with the half-life. BB-10153 had no effect on plasma alpha2-antiplasmin or fibrinogen levels, coagulation assays or bleeding time. An increase in plasminogen was observed as BB-10153 was detected by the enzyme-linked immunosorbent assay (ELISA) for human plasminogen. BB-10153 was well tolerated and had a 3-4-h plasma half-life. Fibrinolytic activity was demonstrated by dose-related ex vivo clot lysis and in vivo production of fibrin D-dimers. These effects were not accompanied by consumption of alpha2-antiplasmin or fibrinogen.