OC 28.5 - A novel experimental model of stable thrombosis: the anti-GPVI agent, glenzocimab, efficiently destabilizes an established thrombus

Background: Models of experimental thrombosis allow to evaluate the impact of anti-platelet agents in the prevention of thrombus formation. However, no models using intravital microscopy, allows to assess the impact of pharmacological agents on a stable thrombus.

Aims: We: i) developed and characterized a model of stable thrombus formation; ii) evaluated the impact of the anti-GPVI agent, glenzocimab on a stable thrombus.

Methods: We developed a model based on a double FeCl3 lesion of the mouse carotid artery leading to stable thrombus formation. Combined observation of platelets, fibrin and red blood cells by intravital imaging, and characterization of the lesion and thrombus by histology, immunofluorescence and electron microscopy allowed to investigate the impact of anti-platelet agents administered 15 min post-injury.

Results: A double-injury of the mouse carotid induces the formation of a platelet-, fibrin- and red blood cell-rich thrombus, which remains stable for more than 45 min. We observed that cangrelor, which targets P2Y12, and eptifibatide, which blocks αIIbβ3, efficiently disaggregate the thrombus. We provide the first evidence that glenzocimab, promotes thrombus destabilization when administered to mice humanized for GPVI. This result also represents the first in vivo evidence of an effect of an anti-GPVI agent in the absence of collagen exposure, as evidenced by transmission electron microscopy. In contrast, no thrombus destabilization was observed in GPVI-deficient mice when compared to WT mice. As only human, but not mouse GPVI binds to fibrinogen, we propose that the destabilization obtained with glenzocimab in the hGPVI mice is the result of an impairment of the human GPVI/fibrinogen interplay.

Conclusion(s): We developed and characterized an in vivo model which allows to evaluate the effect of pharmacological agents on stable arterial thrombi. We provide the first in vivo evidence that targeting human GPVI destabilizes a pre-formed thrombus, in the absence of exposed collagen.