ADPase CD39 Fused to Glycoprotein VI‐Fc Boosts Local Antithrombotic Effects at Vascular Lesions

Abstract

BackgroundGPVI (Glycoprotein VI) is the essential platelet collagen receptor in atherothrombosis. Dimeric GPVI‐Fc (Revacept) binds to GPVI binding sites on plaque collagen. As expected, it did not increase bleeding in clinical studies. GPVI‐Fc is a potent inhibitor of atherosclerotic plaque‐induced platelet aggregation at high shear flow, but its inhibition at low shear flow is limited. We sought to increase the platelet inhibitory potential by fusing GPVI‐Fc to the ectonucleotidase CD39 (fusion protein GPVI‐CD39), which inhibits local ADP accumulation at vascular plaques, and thus to create a lesion‐directed dual antiplatelet therapy that is expected to lack systemic bleeding risks.Methods and Results GPVI‐CD39 effectively stimulated local ADP degradation and, compared with GPVI‐Fc alone, led to significantly increased inhibition of ADP‐, collagen‐, and human plaque–induced platelet aggregation in Multiplate aggregometry and plaque‐induced platelet thrombus formation under arterial flow conditions. GPVI‐CD39 did not increase bleeding time in an in vitro assay simulating primary hemostasis. In a mouse model of ferric chloride–induced arterial thrombosis, GPVI‐CD39 effectively delayed vascular thrombosis but did not increase tail bleeding time in vivo.ConclusionsGPVI‐CD39 is a novel approach to increase local antithrombotic activity at sites of atherosclerotic plaque rupture or injury. It enhances GPVI‐Fc–mediated platelet inhibition and presents a potentially effective and safe molecule for the treatment of acute atherothrombotic events, with a favorable risk–benefit ratio.

Platelet-targeted dual pathway antithrombotic inhibits thrombosis with preserved hemostasis

“…Collagen-targeted GPVI-CD39 represents an alternative strategy, targeting the antiplatelet ADPase CD39 to collagen fibers in the vessel wall. Notably, this promising approach relies on lesion enrichment of CD39 prior to platelet aggregation (48). Similarly, blockade of the intrinsic coagulation pathway has been investigated through the development of antibody, peptide, or antisense inhibitors of FXII (49,50) and FXI (51, 52) as a means to reduce the risk of thrombosis without interfering with hemostasis.…”

Role of Purinergic Signalling in Endothelial Dysfunction and Thrombo-Inflammation in Ischaemic Stroke and Cerebral Small Vessel Disease

“…The efficacy of targeted CD39 against thrombosis was tested when a novel construct of dimeric GPVI-Fc was fused to CD39 (GPVI-CD39), aimed to increase platelet inhibitory potential and to create a lesion-directed dual antiplatelet therapy with minimal bleeding risks [128]. It was found that there was significant inhibition of ADP-induced platelet aggregation as well as significantly delaying ferric chloride induced thrombosis, while not increasing bleeding potential [128].…”

A review of pig liver xenotransplantation: Current problems and recent progress

“…95 The fusion protein, GpVI-CD39, effectively delayed vascular thrombosis without a risk of bleeding. 96 GPIb blockade proved insufficient to prevent platelet activation and sequestration in pig livers perfused with human blood, 97 but a combination of GpIb and GpIIb/IIIa blockade successfully prevented platelet sequestration. 98 Pre-infusion of 1-deamino-8-d-arginine vasopressin to the donor pig reduced vWF content in the lung graft to attenuate platelet activation and complement/coagulation activation.…”

“…The ectonucleotidase CD39 enzymatically degrades ATP and ADP to AMP, which can then be further degraded to adenosine by endothelially expressed CD73 to exert anti‐platelet activity . The fusion protein, GpVI‐CD39, effectively delayed vascular thrombosis without a risk of bleeding . GPIb blockade proved insufficient to prevent platelet activation and sequestration in pig livers perfused with human blood, but a combination of GpIb and GpIIb/IIIa blockade successfully prevented platelet sequestration .…”