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Updated: May 7, 2026

Ferric Chloride-induced Murine Thrombosis Models
Published on: September 5, 2016
Suppression of arterial thrombosis without affecting hemostatic parameters with a cell-penetrating PAR1 pepducin
Ping Zhang1, András Gruber, Shogo Kasuda
1Hemostasis & Thrombosis Laboratory, Tufts Medical Center, Box 7510, 750 Washington St, Boston, MA 02111, USA.
Insights
A novel PAR1 inhibitor, PZ-128, effectively reduces platelet activation and thrombosis during percutaneous coronary intervention without impacting hemostasis. This new therapeutic offers rapid, reversible platelet inhibition for acute coronary syndromes.
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.
Background:
Thrombin-dependent platelet activation is heightened in the setting of percutaneous coronary intervention and may cause arterial thrombosis with consequent myocardial necrosis. Given the high incidence of adverse effects in patients with acute coronary syndromes, there remains an unmet need for the development of new therapeutics that target platelet activation without unduly affecting hemostasis. The thrombin receptor, PAR1, has recently emerged as a promising new target for therapeutic intervention in patients with acute coronary syndromes.
Methods And Results:
We report the development of a first-in-class intracellular PAR1 inhibitor with optimized pharmacokinetic properties for use during percutaneous coronary intervention in patients with acute coronary syndromes. PZ-128 is a cell-penetrating pepducin inhibitor of PAR1 that targets the receptor-G-protein interface on the inside surface of platelets. The structure of PZ-128 closely resembles the predicted off-state of the corresponding juxtamembrane region of the third intracellular loop of PAR1. The onset of action of PZ-128 was rapid and suppressed PAR1 aggregation and arterial thrombosis in guinea pigs and baboons and strongly synergized with oral clopidogrel. There was full recovery of platelet function by 24 hours. Importantly, PZ-128 had no effect on bleeding or coagulation parameters in primates or in blood from patients undergoing percutaneous coronary intervention.
Conclusions:
Based on the efficacy data in nonhuman primates with no noted adverse effects on hemostasis, we anticipate that the rapid onset of platelet inhibition and reversible properties of PZ-128 are well suited to the acute interventional setting of percutaneous coronary intervention and may provide an alternative to long-acting small-molecule inhibitors of PAR1.
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