Parenteral Antiplatelet Drugs in ST-Elevation Myocardial Infarction: Current Status and Future Directions

Oral inhibitors of the platelet P2Y12 receptor are indispensable in the treatment of ST-elevation myocardial infarction (STEMI), improving outcomes and even reducing mortality in some studies. However, these drugs are limited by delayed absorption and suboptimal platelet inhibition at the time of primary percutaneous coronary intervention. Despite efforts to achieve faster and more sustained platelet inhibition, strategies such as prehospital administration, higher loading doses, and crushed formulations have not led to improved coronary reperfusion. Parenteral glycoprotein IIb/IIIa inhibitors act sooner and are more potent than oral P2Y12 inhibitors, but their use has been limited by the increased risk of major bleeding and thrombocytopenia. Hence, there is a clinical need to refine drugs that deliver rapid, effective, yet safe platelet inhibition in the setting of STEMI. Novel parenteral antiplatelet drugs, such as cangrelor, selatogrel, and zalunfiban, have been recently developed to achieve rapid, potent antiplatelet effects while preserving hemostasis. We provide a description of currently available parenteral antiplatelet agents and of those in clinical development for prehospital administration in STEMI patients

Critical Analysis of Thrombocytopenia Associated With Glycoprotein IIb/IIIa Inhibitors and Potential Role of Zalunfiban, a Novel Small Molecule Glycoprotein Inhibitor, in Understanding the Mechanism(s)

Thrombocytopenia is a rare but serious complication of the intravenous glycoprotein IIb/IIIa (GPIIb/IIIa; integrin αIIbβ3) receptor inhibitors (GPIs), abciximab, eptifibatide, and tirofiban. The thrombocytopenia ranges from mild (50 000–100 000 platelets/μL), to severe (20 000 to <50 000/μL), to profound (<20 000/μL). Profound thrombocytopenia appears to occur in <1% of patients receiving their first course of therapy. Thrombocytopenia can be either acute (<24 hours) or delayed (up to ~14 days). Both hemorrhagic and thrombotic complications have been reported in association with thrombocytopenia. Diagnosis requires exclusion of pseudothrombocytopenia and heparin‐induced thrombocytopenia. Therapy based on the severity of thrombocytopenia and symptoms may include drug withdrawals and treatment with steroids, intravenous IgG, and platelet transfusions. Abciximab‐associated thrombocytopenia is most common and due to either preformed antibodies or antibodies induced in response to abciximab (delayed). Readministration of abciximab is associated with increased risk of thrombocytopenia. Evidence also supports an immune basis for thrombocytopenia associated with the 2 small molecule GPIs. The latter bind αIIbβ3 like the natural ligands and thus induce the receptor to undergo major conformational changes that potentially create neoepitopes. Thrombocytopenia associated with these drugs is also immune‐mediated, with antibodies recognizing the αIIbβ3 receptor only in the presence of the drug. It is unclear whether the antibody binding depends on the conformational change and whether the drug contributes directly to the epitope. Zalunfiban, a second‐generation subcutaneous small molecule GPI, does not induce the conformational changes; therefore, data from studies of zalunfiban will provide information on the contribution of the conformational changes to the development of GPI‐associated thrombocytopenia

Pre-hospital treatment with zalunfiban (RUC-4) in patients with ST- Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention: Rationale and design of the CELEBRATE trial

BACKGROUND: Early and complete restoration of target vessel patency in ST-elevation myocardial infarction (STEMI) is associated with improved outcomes. Oral P2Y12 inhibitors have failed to demonstrate either improved patency or reduced mortality when administered in the pre-hospital setting. Thus, there is a need for antiplatelet agents that achieve prompt and potent platelet inhibition, and that restore patency in the pre-hospital setting. Zalunfiban, a novel subcutaneously administered glycoprotein IIb/IIIa inhibitor designed for pre-hospital administration, has shown to achieve rapid, high-grade platelet inhibition that exceeds that of P2Y12 inhibitors. Whether pre-hospital administration of zalunfiban can improve clinical outcome is unknown. HYPOTHESIS: The present study is designed to assess the hypothesis that a single, pre-hospital injection of zalunfiban given in the ambulance, in addition to standard-of-care in patients with STEMI with intent to undergo primary percutaneous coronary intervention (PCI) will improve clinical outcome compared to standard-of-care with placebo. STUDY DESIGN: The ongoing CELEBRATE trial (NCT04825743) is a phase III, randomized, double-blinded, placebo-controlled, international trial. Patients with STEMI intended to undergo primary PCI will receive treatment with a single subcutaneous injection containing either zalunfiban dose 1 (0.110 mg/kg), zalunfiban dose 2 (0.130 mg/kg) or placebo, and the study drug will be administered in the ambulance before transportation to the hospital. A target of 2499 patients will be randomly assigned to one of the treatment groups in a 1:1:1 ratio, i.e., to have approximately 833 evaluable patients per group. The primary efficacy outcome is a ranked 7-point scale on clinical outcomes. The primary safety outcome is severe or life-threatening bleeding according to the Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) criteria. SUMMARY: The CELEBRATE trial will assess whether a single pre-hospital subcutaneous injection of zalunfiban in addition to standard-of-care in patients with STEMI with intent to undergo primary PCI will result in improved clinical outcome

Dual versus triple antithrombotic therapy after percutaneous coronary intervention:the prospective multicentre WOEST 2 Study

BACKGROUND: For patients with oral anticoagulants (OAC) undergoing percutaneous coronary intervention (PCI), European guidelines have recently changed their recommendations to dual antithrombotic therapy (DAT; P2Y12 inhibitor and OAC) without aspirin. AIMS: The prospective WOEST 2 registry was designed to obtain contemporary real-world data on antithrombotic regimens and related outcomes after PCI in patients with an indication for OAC. METHODS: In this analysis, we compare DAT (P2Y12 inhibitor and OAC) to triple antithrombotic therapy (TAT; aspirin, P2Y12 inhibitor, and OAC) on thrombotic and bleeding outcomes after one year. Clinically relevant bleeding was defined as Bleeding Academic Research Consortium classification (BARC) grade 2, 3, or 5; major bleeding as BARC grade 3 or 5. Major adverse cardiac and cerebrovascular events (MACCE) was defined as a composite of all-cause mortality, myocardial infarction, stent thrombosis, ischaemic stroke, and transient ischaemic attack. RESULTS: A total of 1,075 patients were included between 2014 and 2021. Patients used OAC for atrial fibrillation (93.6%) or mechanical heart valve prosthesis (4.7%). Non-vitamin K oral anticoagulant (NOAC) was prescribed in 53.1% and vitamin K antagonists in 46.9% of patients. At discharge, 60.9% received DAT, and 39.1% TAT. DAT was associated with less clinically relevant and similar major bleeding (16.8% vs 23.4%; p<0.01 and 7.6% vs 7.7%, not significant), compared to TAT. MACCE was not statistically significant different (12.4% vs 9.7%; p=0.17). Multivariable adjustment and propensity score matching confirmed these results. CONCLUSIONS: Dual antithrombotic therapy is associated with a substantially lower risk of clinically relevant bleeding without a statistically significant penalty in ischaemic events