Delayed targeting of CD39 to activated platelet GPIIb/IIIa via a single-chain antibody: breaking the link between antithrombotic potency and bleeding?

Abstract

The ecto-nucleoside triphosphate diphosphohydrolase CD39 represents a promising antithrombotic therapeutic. It degrades adenosine 5'-diphosphate (ADP), a main platelet activating/recruiting agent. We hypothesized that delayed enrichment of CD39 on developing thrombi will allow for a low and safe systemic concentration and thus avoid bleeding. We use a single-chain antibody (scFv, specific for activated GPIIb/IIIa) for targeting CD39. This should allow delayed enrichment on growing thrombi but not on the initial sealing layer of platelets, which do not yet express activated GPIIb/IIIa. CD39 was recombinantly fused to an activated GPIIb/IIIa-specific scFv (targ-CD39) and a nonfunctional scFv (non-targ-CD39). Targ-CD39 was more effective at preventing ADP-induced platelet activation than non-targ-CD39. In a mouse carotid artery thrombosis model, non-targ-CD39, although protective against vessel occlusion, was associated with significant bleeding on tail transection. In contrast, targ-CD39 concentrated at the thrombus site; hence, a dose ∼10 times less of CD39 prevented vessel occlusion to a similar extent as high-dose non-targ-CD39, without prolonged bleeding time. An equimolar dose of non-targ-CD39 at this low concentration was ineffective at preventing vessel occlusion. Thus, delayed targeting of CD39 via scFv to activated platelets provides strong antithrombotic potency and yet prevents bleeding and thereby promotes CD39 toward clinical use.

• Authors: Jan David Hohmann, Xiaowei Wang, Stefanie Krajewski, Carly Selan, Carolyn A Haller, Andreas Straub, Elliot L Chaikof, Harshal H Nandurkar, Christoph E Hagemeyer, Karlheinz Peter
• Journal: Blood (Blood) Vol. 121 Issue 16 Pg. 3067-75 (Apr 18 2013) ISSN: 1528-0020 [Electronic] United States
• PMID: 23380744 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Antigens, CD
• Fibrinolytic Agents
• Platelet Glycoprotein GPIIb-IIIa Complex
• Recombinant Fusion Proteins
• Single-Chain Antibodies
• Adenosine Diphosphate
• Apyrase
• CD39 antigen

Topics

• Adenosine Diphosphate (metabolism)
• Animals
• Antigens, CD (genetics, therapeutic use)
• Apyrase (genetics, therapeutic use)
• Blood Platelets (drug effects, pathology)
• Drug Delivery Systems
• Fibrinolytic Agents (metabolism, therapeutic use)
• Humans
• Male
• Mice
• Mice, Inbred C57BL
• Platelet Activation (drug effects)
• Platelet Glycoprotein GPIIb-IIIa Complex (metabolism)
• Recombinant Fusion Proteins (genetics, therapeutic use)
• Single-Chain Antibodies (genetics, therapeutic use)
• Thrombosis (drug therapy, metabolism, pathology)