Prehospital treatment with zalunfiban (RUC-4) in patients with ST- elevation myocardial infarction undergoing primary percutaneous coronary intervention: Rationale and design of the CELEBRATE trial

Current and Future Roles of Glycoprotein IIb-IIIa Inhibitors in Primary Angioplasty for ST-Segment Elevation Myocardial Infarction

Acute myocardial infarction still represents the major cause of mortality in high-income countries. Therefore, considerable efforts have been focused on the treatment of myocardial infarctions in the acute and long-term phase, with special attention being paid to reperfusion strategies and adjunctive antithrombotic therapies. In fact, despite the successful mechanical recanalization of the epicardial conduit, a substantial percentage of patients still experience poor myocardial reperfusion or acute/subacute in-stent thrombosis. Due the delayed onset of action of currently available oral antiplatelet therapies, glycoprotein (GP) IIb-IIIa inhibitors could be expected to improve clinical outcomes, especially when administrated in the early phase of the infarction, due to the larger platelet composition of fresh thrombi, the dynamic nature of early thrombi, and the larger amount of viable myocardium existing in the early, as compared to a delayed, phase. Considerable evidence has accumulated regarding the benefits from GP IIb-IIIa inhibitors on mortality, especially among high-risk patients and when administered as an upstream strategy. Therefore, based on currently available data, GP IIb-IIIa inhibitors can be considered when the drug can be administered within the first 3 h of symptom onset and among high-risk patients (e.g., those with advanced Killip class or an anterior myocardial infarction). Even though it is not universally accepted, in our opinion, this strategy should be implemented in a pre-hospital setting (in an ambulance) or as soon as possible when arriving at the hospital (at the Emergency Room or Coronary Care Unit, irrespective of whether they are in spoke or hub hospitals). A new, second-generation GP IIb-IIIa inhibitor (zalunfiban) appears to be highly suitable as a pre-hospital pharmacological facilitation strategy at the time of first medical contact due to its favourable features, including its simple subcutaneous administration, rapid onset of action (15 min), and limited time of action (with a half-life of ~1 h), which is likely to minimize the risk of bleeding. The ongoing CELEBRATE trial, including 2499 STEMI patients, may potentially provide compelling data to support the upstream treatment of STEMI patients undergoing mechanical reperfusion. In fact, although the current therapeutic target of increased rates of timely reperfusion has been achieved, the future goal in myocardial infarction treatment should be to achieve the most rapid reperfusion prior to primary percutaneous coronary intervention, thus further minimizing myocardial damage, or, in some cases, even preventing it completely, and improving survival.

Prehospital tirofiban increases the rate of disrupted myocardial infarction in patients with ST-segment elevation myocardial infarction: insights from the On-TIME 2 trial

AIMS

In patients with ST-segment elevation myocardial infarction (STEMI), prehospital tirofiban significantly improved myocardial reperfusion. However, its impact on the rate of disrupted myocardial infarction (MI), particularly in the context of high-sensitivity cardiac troponin (hs-cTn) assays, is still unclear.

METHODS AND RESULTS

The On-TIME 2 (Ongoing Tirofiban In Myocardial infarction Evaluation 2) trial randomly assigned STEMI patients to prehospital tirofiban or placebo before transportation to a percutaneous coronary intervention (PCI) centre. In this post hoc analysis, we evaluated STEMI patients that underwent primary PCI and had measured hs-cTn levels. Troponin T levels were collected at 18-24 and 72-96 h after PCI. Disrupted MI was defined as peak hs-cTn T levels ≤ 10 times the upper limit of normal (≤140 ng/L). Out of 786 STEMI patients, 47 (6%) had a disrupted MI. Disrupted MI occurred in 31 of 386 patients (8.0%) in the tirofiban arm and in 16 of 400 patients (4.0%) in the placebo arm (P = 0.026). After multivariate adjustment, prehospital tirofiban remained independently associated with disrupted MI (odds ratio 2.03; 95% confidence interval 1.10-3.87; P = 0.027). None of the patients with disrupted MI died during the 1-year follow-up, compared with a mortality rate of 2.6% among those without disrupted MI.

CONCLUSION

Among STEMI patients undergoing primary PCI, the use of prehospital tirofiban was independently associated with a higher rate of disrupted MI. These results, highlighting a potential benefit, underscore the need for future research focusing on innovative pre-treatment approaches that may increase the rate of disrupted MI.

Safety and effectiveness of glycoprotein IIb/IIIa inhibitors in acute coronary syndromes: insights from the SPUM-ACS study

AIMS

Data on glycoprotein IIb/IIIa inhibitor (GPI) use in real-world acute coronary syndrome (ACS) patients following the introduction of potent P2Y12 inhibitors and newer-generation stents are scant. Here, we aimed to assess the utilization, effectiveness, and safety of GPI in a large prospective multicentre cohort of contemporary ACS patients.

METHODS AND RESULTS

SPUM-ACS prospectively recruited patients presenting with ACS between 2009 and 2017. The primary endpoint of the present study was major adverse cardiovascular events (MACE), a composite of all-cause death, non-fatal myocardial infarction, and non-fatal stroke at 1 year. Secondary endpoints were defined as any bleeding events, Bleeding Academic Research Consortium (BARC) 3-5 bleeding, and net adverse cardiovascular events (NACE). A total of 4395 ACS patients were included in the analysis. GPI-treated patients had more total coronary artery occlusion (56% vs. 35%, P < 0.001) and thrombus (60% vs. 35%, P < 0.001) at angiography. Among the propensity score-matched (PSM) population (1992 patients equally split into two groups), GPI-treated patients showed lower risk of MACE [PSM adjusted hazard ratio (HR) 0.70, 95% CI 0.49-0.99], but a higher risk of any (PSM adjusted HR 1.46, 95% CI 1.06-1.99) and major bleedings (PSM adjusted HR 1.73, 95% CI 1.09-2.76), resulting in a neutral effect on NACE (PSM adjusted HR 0.87, 95% CI 0.65-1.17). These results remained consistent across all subgroups.

CONCLUSIONS

In patients with ACS undergoing percutaneous coronary intervention and receiving potent P2Y12 inhibitors, we observed a reduced risk of MACE and an increased risk of major bleedings at 1 year in patients treated with GPI. Although the routine use of GPI is currently not recommended, they might be considered in selected patients following a personalized balancing between ischaemic and bleeding risks.

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.

Comparison of the effects of the GPIIb-IIIa antagonist Zalunfiban and the P2Y12 antagonist Selatogrel on Platelet Aggregation

Understanding the pharmacodynamic effects of platelet inhibitors is standard for developing more effective antithrombotic therapies. An example is the antithrombotic treatment of acute coronary syndrome (ACS), in particular ST-elevated myocardial infarction (STEMI) patients who are in need for rapid acting strong antithrombotic therapy despite the use of aspirin and oral P2Y12-inhibitors. In this study, we evaluated two injectable platelet inhibitors under clinical development (the P2Y12 antagonist selatogrel and the GPIIb-IIIa antagonist zalunfiban) that may be amenable to pre-hospital treatment of STEMI patients. Platelet reactivity was assessed at inhibitor concentrations that represent clinically relevant levels of platelet inhibition (IC20-50%, 1/2Cmax, and Cmax). Light transmission aggregometry (LTA), was used to evaluate the initial rate of aggregation (primary slope, PS) and maximal aggregation (MA). Both adenosine diphosphate (ADP) and thrombin receptor agonist peptide (TRAP) were used as agonists. Zalunfiban demonstrated similar inhibition of platelet aggregation when blood was collected in PPACK or TSC, whereas selatogrel demonstrated greater inhibition in PPACK. In this study, using PPACK anticoagulant, selatogrel and zalunfiban affected PS in response to ADP equivalently at all drug concentrations tested. In contrast, zalunfiban had significantly greater potency at its Cmax concentration compared to selatogrel using TRAP as agonist. Upon evaluation of MA responses at lower doses, selatogrel had greater inhibition of MA in response to ADP than zalunfiban; however, at concentrations that represent Cmax, the drugs were equivalent. Zalunfiban also had greater inhibition of MA in response to TRAP at the Cmax dose. These data suggest that zalunfiban may provide greater protection in reducing thrombus formation than selatogrel, especially since thrombin is an early, key primary agonist in the pathophysiology of thrombotic events.

Integrin signaling in cancer: bidirectional mechanisms and therapeutic opportunities

Integrins are transmembrane receptors that possess distinct ligand-binding specificities in the extracellular domain and signaling properties in the cytoplasmic domain. While most integrins have a short cytoplasmic tail, integrin β4 has a long cytoplasmic tail that can indirectly interact with the actin cytoskeleton. Additionally, 'inside-out' signals can induce integrins to adopt a high-affinity extended conformation for their appropriate ligands. These properties enable integrins to transmit bidirectional cellular signals, making it a critical regulator of various biological processes.Integrin expression and function are tightly linked to various aspects of tumor progression, including initiation, angiogenesis, cell motility, invasion, and metastasis. Certain integrins have been shown to drive tumorigenesis or amplify oncogenic signals by interacting with corresponding receptors, while others have marginal or even suppressive effects. Additionally, different α/β subtypes of integrins can exhibit opposite effects. Integrin-mediated signaling pathways including Ras- and Rho-GTPase, TGFβ, Hippo, Wnt, Notch, and sonic hedgehog (Shh) are involved in various stages of tumorigenesis. Therefore, understanding the complex regulatory mechanisms and molecular specificities of integrins are crucial to delaying cancer progression and suppressing tumorigenesis. Furthermore, the development of integrin-based therapeutics for cancer are of great importance.This review provides an overview of integrin-dependent bidirectional signaling mechanisms in cancer that can either support or oppose tumorigenesis by interacting with various signaling pathways. Finally, we focus on the future opportunities for emergent therapeutics based on integrin agonists. Video Abstract.

Clinical pharmacology of selatogrel for self-administration by patients with suspected acute myocardial infarction

INTRODUCTION

P2Y12 receptor antagonists (P2Y12 inhibitors) are well established for the treatment of coronary artery disease. The P2Y12 inhibitors currently commercially available present either pharmacokinetic limitations (due to delayed absorption, bioactivation requirement via CYP enzymes, or need of intravenous administration), pharmacodynamic (PD) limitations (limited % inhibition of platelet aggregation (IPA) or relevant PD interactions) or safety limitations (major bleeding in specific populations).

AREAS COVERED

Selatogrel, a 2-phenylpyrimidine-4-carboxamide analog, is a potent, reversible, and selective P2Y12 inhibitor administered subcutaneously that is under development for the treatment of acute myocardial infarction (AMI) in patients with a recent history of AMI. In this review, the authors summarize the results from preclinical, phase 1, and phase 2 trials which showed that selatogrel provides rapid, pronounced, and reversible P2Y12 receptor inhibition with a favorable safety profile.

EXPERT OPINION

These unique characteristics added to the limited potential to interact with co-medications and manageable PD interactions with other P2Y12 inhibitors provide a clear rationale for investigating the benefit of selatogrel as an emergency treatment to improve clinical outcomes in patients with AMI.