Optimal timing of intervention in NSTE-ACS without pre-treatment

Introduction In patients (P) with non-ST segment elevation acute coronary syndromes (NSTE-ACS), an invasive strategy is recommended to reduce adverse outcomes. The optimal timing to perform coronary angiography (CA) remains undetermined, particularly in our era attending to the new European guidelines restricting pre-treatment (PT). Objective To evaluate the prognostic value of an early strategy (ES; <24h) versus a delayed strategy (DS; >24h) when no loading dose of a P2Y12 antagonist was given as PT in NSTE-ACS. Material and methods Retrospective analysis of P data admitted with NSTE-ACS at multicentric national registry between 2015–19. Compared demographic and clinical characteristics of P with an ES versus DS. A multivariate logistic regression was performed to evaluate predictor factors of in-hospital and 1-year endpoints. Survival was evaluated through Kaplan-Meier curve and Cox multivariate regression. Results 691P were included, mean age 64±11 years, 77.4% male. 59.2% performed CA as an ES. P proposed to a DS presented higher KK class, higher levels of creatinine and lower of hemoglobin. They also needed more frequently invasive (1.1 vs 0.7%, p=0.692) or non-invasive ventilation (1.8 vs 0.7%, p=282). A higher proportion of DS patients used the transfemoral access (5.5 vs 9.3%, p=0.058). On CA, 6.2% had normal coronary arteries, 49.2% 1-vessel disease and 45.1% multivessel disease. Revascularization was performed in 88.2%: PCI in 86.2%, CABG in 1.7% and both in 0.3%, with no significant differences. Pending CA, 98.4% were medicated with aspirin, 64.8% ticagrelor and 44% clopidogrel, with no differences. P proposed to an ES were more medicated with glycoprotein inhibitor (36.3 vs 26.4%, p=0.015) and non-fractioned heparin (6.4 vs 2.1%, p=0.01) and less with fondaparinux (56.2 vs 65.2%, p=0.017). A higher percentage of calcium-channel blockers (25.2 vs 11.7%, p<0.001) and nitrates (74.1 vs 53.3%, p<0.001) was observed in the DS. No difference was observed in beta-blockers (p=0.581). Discharge medication followed these tendencies. There was a trend to worse in-hospital outcomes in the DS regarding heart failure, shock, ventricular arrhythmias, cardiac arrest and death, although not significatively different, except for major bleeding (1.8 vs 0.2%, p=0.044). 1-year composite endpoint of mortality and cardiovascular rehospitalization occurred in 9.9%, with no difference between groups (p=0.181). Predictor factors, evaluated through Cox multivariate regression, were ejection fraction <50% (p=0.001), KK class >I (p=0.002) and nitrate prescription at discharge (p=0.001). A DS was not a predictor factor (p=0.812). Conclusion Our results are in accordance with available data. In P with higher-risk NSTE-ACS in the absence of P2Y12 antagonist PT, an ES was not associated with a reduction in the composite of global mortality and rehospitalization for cardiovascular causes. FUNDunding Acknowledgement Type of funding sources: None.

Aberrant glycosylation of anti-SARS-CoV-2 IgG is a pro-thrombotic stimulus for platelets

A subset of patients with COVID-19 become critically ill, suffering from severe respiratory problems and also increased rates of thrombosis. The causes of thrombosis in severely ill COVID-19 patients are still emerging, but the coincidence of critical illness with the timing of the onset of adaptive immunity could implicate an excessive immune response. We hypothesised that platelets might be susceptible to activation by anti-SARS-CoV-2 antibodies and contribute to thrombosis. We found that immune complexes containing recombinant SARS-CoV-2 spike protein and anti-spike IgG enhanced platelet-mediated thrombosis on von Willebrand Factor in vitro, but only when the glycosylation state of the Fc domain was modified to correspond with the aberrant glycosylation previously identified in patients with severe COVID-19. Furthermore, we found that activation was dependent on FcγRIIA and we provide in vitro evidence that this pathogenic platelet activation can be counteracted by therapeutic small molecules R406 (fostamatinib) and ibrutinib that inhibit tyrosine kinases Syk and Btk respectively or by the P2Y12 antagonist cangrelor.

Aberrant glycosylation of anti-SARS-CoV-2 IgG is a pro-thrombotic stimulus for platelets

A subset of patients with COVID-19 become critically ill, suffering from severe respiratory problems and also increased rates of thrombosis. The causes of thrombosis in severely ill COVID-19 patients are still emerging, but the coincidence of critical illness with the timing of the onset of adaptive immunity could implicate an excessive immune response. We hypothesised that platelets might be susceptible to activation by anti-SARS-CoV-2 antibodies and contribute to thrombosis. We found that immune complexes containing recombinant SARS-CoV-2 spike protein and anti-spike IgG enhanced platelet-mediated thrombosis on von Willebrand Factor in vitro, but only when the glycosylation state of the Fc domain was modified to correspond with the aberrant glycosylation previously identified in patients with severe COVID-19. Furthermore, we found that activation was dependent on FcγRIIA and we provide in vitro evidence that this pathogenic platelet activation can be counteracted by therapeutic small molecules R406 (fostamatinib) and ibrutinib that inhibit tyrosine kinases syk and btk respectively or by the P2Y12 antagonist cangrelor.

Favorable therapeutic index of an orally-active small-molecule antagonist of the platelet protease-activated receptor-4, BMS-986141, compared with the P2Y12 antagonist ticagrelor in cynomolgus monkeys

Introduction BMS-986141 is an orally-active small-molecule platelet thrombin receptor antagonist selective for the protease-activated receptor-4 (PAR4), a human platelet thrombin receptor. Purpose This study assessed effects of BMS-986141 vs. the P2Y12 antagonist ticagrelor, a standard of care antiplatelet agent, on arterial thrombosis (AT), mesenteric bleeding time (MBT) and platelet aggregation in monkeys. Methods Studies were conducted in models of electrically-mediated carotid artery thrombosis and MBT in anesthetized monkeys. Monkeys were given a single oral dose of BMS-986141 (0.05, 0.1, 0.5 mg/kg) or vehicle (n=8/group). At 2 hr post-dose, in vivo AT, MBT as well as ex vivo platelet aggregation were monitored in the same animal. Ticagrelor was studied as a comparator and given as IV bolus plus infusion at 0.0023+0.017 to 0.075+0.6 (mg/kg+mg/kg/h) (n=5–6/group). Thrombus weight reduction, MBT increase over vehicle, and platelet aggregation inhibition were determined. Peak platelet aggregation responses to activation peptides selective for PAR4 (PAR4-AP, 12.5 μM) and PAR1 (PAR1-AP, 18 μM), to collagen (5 μg/ml) and to ADP (20 μM) were determined by whole blood aggregometry. Results BMS-986141 inhibited platelet aggregation induced by PAR4-AP in human and monkey blood in vitro with comparable IC50 of 1.8±0.3 and 1.2±0.3 nM, respectively. BMS-986141 at 0.5 mg/kg completely inhibited platelet aggregation induced by PAR4-AP but not PAR1-AP, ADP and collagen, suggesting PAR4 receptor selectivity. In the AT model, BMS-986141 at 0.05, 0.1 and 0.5 mg/kg reduced thrombus weight by 36±7*, 63±8*, and 88±3%*, respectively (*P<0.05 vs. vehicle). BMS-986141 increased MBT by up to 1.2-fold. In a separate study, ticagrelor at 0.0023+0.017, 0.0068+0.055, 0.0255+0.18 and 0.075+0.6 (mg/kg+mg/kg/h IV) reduced thrombus weight by 19±8, 36±5*, 76±6* and 89±1%*, and increased MBT by respectively by 1.7-, 6.4-*, >10-*, and >10-fold*, respectively (*P<0.05 vs. vehicle). Conclusion Comparable antithrombotic efficacy was observed between BMS-986141 and ticagrelor in monkeys. BMS-986141 exhibited lower MBT compared with ticagrelor at equivalent antithrombotic doses. This study suggests that PAR4 antagonism provides a potentially safer antiplatelet therapy. Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Research was supported by Bristol-Myers Squibb

In Vitro Effects of the Novel Platelet αIIbβ3 Receptor Antagonist RUC-4 on the Verifynow Assays: Potential for Point-of-Care Monitoring of RUC-4 Therapy

Introduction: RUC-4 is a novel platelet integrin αIIbβ3 antagonist specifically designed for first point-of-medical contact (ambulance or ER) treatment of patients with ST segment elevation myocardial infarction in combination with aspirin. Ongoing Phase 1 studies indicate that RUC-4 at a dose of 0.075 mg/kg administered subcutaneously can inhibit ADP-induced platelet aggregation by ~80% within 15 minutes, with a return toward baseline within 60-90 minutes. It may be advantageous to monitor the antiplatelet effects of RUC-4 on admission to the hospital, but optical aggregometry (OA) takes too long to guide immediate therapeutic decisions. The automated VerifyNow (VN) assays provide rapid point-of-care assessment of the effect of antiplatelet agents. The VN IIb/IIIa assay uses a thrombin receptor activating peptide (isoTRAP) to activate the platelets and the VN Aspirin assay uses arachidonic acid, whereas the PRU (P2Y12) assay uses isoTRAP in one channel and a mixture of ADP and PGE1 in another. We recently reported that: 1. Aspirin does not affect the IC50 for RUC-4 when measured by OA of platelet-rich plasma (PRP) in response to ADP, and 2. The IC50 is lower in PRP that is prepared from blood anticoagulated with citrate rather than PPACK, consistent with RUC-4's mechanism of action in displacing the Mg2+ ion from the MIDAS domain (Vootukuri et al., J Clin Transl Sci; in press). We now have explored the sensitivity of the VN assays to RUC-4 and the effects of aspirin and different anticoagulants. Methods: Whole blood anticoagulated with either sodium citrate (0.32%) or PPACK (100 µM) from healthy volunteers who were either taking or not taking daily aspirin was treated in vitro with RUC-4 to achieve final whole blood concentrations between 30 and 900 nM. Blood was incubated for 10 minutes at room temperature and then tested with either the IIb/IIIa or PRU cartridge. Results: Whole blood samples were obtained from 13 healthy volunteers who provided consent, of whom 7 were taking aspirin. The antiplatelet effect of aspirin in the latter 7 participants was confirmed with the VN Aspirin assay. 1. PPACK vs citrate anticoagulation in blood from individuals who were not treated with aspirin. The percent inhibition values produced by different concentrations of RUC-4 in whole blood anticoagulated with either PPACK or citrate and activated with isoTRAP were highly correlated (R2=0.95; p<0.01) despite differences in absolute values (IC50s of 141 ± 5 vs 88 ± 7 nM, respectively, p=0.01; n=6). The comparable values using ADP+PGE1 as the activator were also highly correlated (R2=0.95; p<0.01) despite differences in absolute values (IC50s of 128 ± 5 vs 69 ± 8 nM, p=0.01; n=6). Based on these results, we selected citrate-anticoagulated blood for additional studies because vacuum blood collection tubes containing citrate, but not PPACK, are available commercially. 2. Effect of RUC-4 on VN assays: a) Impact of aspirin on results in the PRU cartridge. The IC50s in the isoTRAP channel were similar using blood from individuals who were not taking aspirin (88 ± 7 nM) or taking aspirin (97 ± 20 nM; p=0.35; n=9). Similar results were obtained using the ADP+ PGE1 channel (69 ± 8 vs 70 ± 8 nM; p=0.84; n=9). b) Comparison of the 2 different isoTRAP channels with blood from people on aspirin. RUC-4 showed similar dose-responses in both isoTRAP channels, with an IC50 of 79 ± 26 nM in the IIb/IIIa cartridge vs 97 ± 20 nM in the PRU cartridge (p=0.12; n=5). c) Comparison of the isoTRAP vs ADP+PGE1 channel using blood from people on aspirin. The ADP+PGE1 channel was more sensitive to the lower concentrations of RUC-4 than the isoTRAP channel, showing, for example, ~40% inhibition at 30 nM compared to ~20%, respectively (Figure; p<0.02 based on comparison of IC50s ). Discussion: We conclude that RUC-4 produces dose-dependent inhibition of the VN isoTRAP channels in both the IIb/IIIa and PRU cartridges, as well as the ADP+PGE1 channel in the PRU cartridge. The PRU cartridge ADP+PGE1 channel is more sensitive than the isoTRAP channel to low concentrations of RUC-4. Since P2Y12 antagonists inhibit the ADP+PGE1 channel, but not the isoTRAP channels, the effect of RUC-4 on patients who are not treated with a P2Y12 antagonist may be monitored with the PRU ADP+PGE1 channel or the isoTRAP channel in either the PRU or IIb/IIIa cartridge. The RUC-4 effects in patients treated with a P2Y12 antagonist may be monitored with the isoTRAP channel in either cartridge. Figure Disclosures Coller: Accumetrics/Instrumentation Laboratory: Patents & Royalties: VerifyNow assay; Scholar Rock: Consultancy, Equity Ownership; CeleCor: Consultancy, Equity Ownership, Research Funding; Centocor/Janssen: Patents & Royalties: abxicimab.

Selection of P2Y12 antagonist in patients with myocardial infarction who received thrombolytic therapy. Results of annual follow-up of TREAT study patients

Dual antiplatelet therapy serves to improve the clinical results of thrombolytic therapy after STEMI, until recently consisted of acetylsalicylic acid and clopidogrel. In this category of patients, ticagrelor, widely used by acute coronary syndrome as more effective than clopidogrel, had no serious evidence of efficacy and safety. The TREAT study discussed in this article has been implemented to supply a gap in the evidence base of ticagrelor. The results of observation within 12 months after randomization to taking ticagrelor or clopidogrel of patients who received thrombolytic showed that the hemorrhagic safety regarding the major bleeding of ticagrelor is comparable with clopidogrel. The results of the TREAT study with the previously obtained results of the PLATO study make it possible to broaden indications for the use of ticagrelor (or switching from clopidogrel) in the first 24 hours from the onset of a myocardial infarction in patients who received thrombolytic therapy as an initial reperfusion.