Suppression of arterial thrombosis without affecting hemostatic parameters with a cell-penetrating PAR1 pepducin

Area of Science:

• Cardiovascular Medicine
• Pharmacology
• Thrombosis Research

Background:

• Percutaneous coronary intervention (PCI) heightens thrombin-dependent platelet activation, increasing arterial thrombosis risk and myocardial necrosis in acute coronary syndromes.
• Existing treatments face challenges with adverse effects, highlighting the need for novel therapeutics targeting platelet activation while preserving hemostasis.
• The protease-activated receptor 1 (PAR1) is a key mediator of thrombin signaling and an emerging target for antiplatelet therapy.

Purpose of the Study:

• To develop and characterize a first-in-class intracellular PAR1 inhibitor (PZ-128) for use in PCI.
• To evaluate the pharmacokinetic properties, efficacy, and safety of PZ-128 in preclinical models.

Main Methods:

• Development of PZ-128, a cell-penetrating pepducin targeting the PAR1 receptor-G-protein interface.
• Assessment of PZ-128's rapid onset, platelet aggregation suppression, and anti-thrombotic effects in guinea pigs and baboons.
• Evaluation of PZ-128's impact on bleeding and coagulation parameters in primates and human blood samples.

Main Results:

• PZ-128 demonstrated rapid onset of action, suppressing PAR1-mediated platelet aggregation and arterial thrombosis in vivo.
• The inhibitor showed strong synergy with clopidogrel and full recovery of platelet function within 24 hours.
• Crucially, PZ-128 did not affect bleeding or coagulation parameters in primates or human blood, indicating a favorable safety profile.

Conclusions:

• PZ-128 exhibits potent antiplatelet activity with a rapid onset and reversible effect, suitable for acute PCI settings.
• The lack of adverse effects on hemostasis suggests PZ-128 may offer a safer alternative to existing PAR1 inhibitors.
• PZ-128 represents a promising therapeutic candidate for managing platelet activation in patients undergoing PCI for acute coronary syndromes.