Prourokinase mutant that induces highly effective clot lysis without interfering with hemostasis.
Prourokinase (proUK) is a zymogenic plasminogen activator that at pharmacological doses is prone to nonspecific activation to urokinase. This has handicapped therapeutic exploitation of its fibrin-specific physiological properties. To attenuate this susceptibility without compromising specific activation of proUK on a fibrin clot, a Lys300-->His mutation (M5) was developed. M5 had a lower intrinsic activity and, therefore, remained stable in plasma at a 4-fold higher concentration than did proUK. M5 had a higher 2-chain activity and induced more rapid plasminogen activation and fibrin-specific clot lysis in vitro. Sixteen dogs embolized with radiolabeled clots were infused with saline, proUK, tissue plasminogen activator, or M5. The lower intrinsic activity allowed a higher infusion rate with M5, which induced the most rapid and efficient clot lysis (50% clot lysis by approximately 600 microg/kg M5 versus approximately 1200 microg/kg proUK). In association with this, M5 caused neither a significant increase in the primary bleeding time nor secondary bleeding (total blood loss). By contrast, these measurements increased 4-fold and 5-fold, respectively, with proUK and >5-fold and 8-fold, respectively, with tissue plasminogen activator. Clot lysis by M5 and hemostasis were further evaluated in 6 rhesus monkeys. M5 again induced rapid clot lysis without a significant increase in the primary bleeding time, and secondary bleeding did not occur. In conclusion, a site-directed mutation designed to improve the stability of proUK in blood at therapeutic concentrations induced superior clot lysis in vitro and in vivo without causing significant interference with hemostasis.
Liu
Jian-Ning
JN
Vascular Research Laboratory, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215-5400, USA. jnliu@prodigy.net
Liu
Jian-Xia
JX
Liu Bf
Bei-fang
BF
Sun
Ziyong
Z
Zuo
Jian-Ling
JL
Zhang Px
Pei-xiang
PX
Zhang
Jing
J
Chen Yh
Yu-hong
YH
Gurewich
Victor
V
D019943:Amino Acid Substitution; D000818:Animals; D001760:Bleeding Time; D001777:Blood Coagulation / Q000187:drug effects*; D004195:Disease Models, Animal; D004285:Dogs; D004353:Drug Evaluation, Preclinical; D004355:Drug Stability; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D005268:Femoral Vein / Q000187:drug effects; D005337:Fibrin / Q000187:drug effects / Q000378:metabolism; D005342:Fibrinolysis / Q000187:drug effects*; D006470:Hemorrhage / Q000517:prevention & control; D006487:Hemostasis / Q000187:drug effects*; D006801:Humans; D008253:Macaca mulatta; D008297:Male; D016297:Mutagenesis, Site-Directed; D010949:Plasma / Q000187:drug effects / Q000378:metabolism; D010958:Plasminogen / Q000187:drug effects / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D015912:Thrombolytic Therapy / Q000379:methods*; D013927:Thrombosis / Q000188:drug therapy*; D010959:Tissue Plasminogen Activator / Q000494:pharmacology; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*
D011994:Recombinant Proteins; D005337:Fibrin; D010958:Plasminogen; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator; C067551:saruplase