Effect of Interleukin-6 Receptor Inhibition by Tocilizumab on Platelet Activation and Markers of Thrombus Formation: A Substudy of the ASSAIL-MI Trial

BACKGROUND: The bidirectional interaction between inflammation and thrombus formation plays an important role in myocardial infarction (MI) with IL (interleukin)-6 as a central mediator. If anti-inflammatory therapy modulates coagulation factors, and platelet activation in patients with MI is not clear. METHODS: We have shown that tocilizumab, a monoclonal antibody targeting IL-6R (IL-6 receptor), improves myocardial salvage index in patients with ST-elevation MI. Herein, we measured levels of soluble markers of platelet activation (P-selectin, sCD40L [soluble CD40 ligand]) and coagulation (TF [tissue factor], TFPI [TF pathway inhibitor], PAI [plasminogen activator inhibitor]-1, and D-dimer) in 136 patients with ST-segment-elevation MI (70 tocilizumab and 66 placebo). Platelet-poor EDTA plasma samples were obtained at admission and after 24 and 168 hours. Temporal changes were related to TnT (troponin T), as well as infarct size and myocardial salvage index, assessed by cardiac magnetic resonance imaging. RESULTS: Our major findings were given as follows: (1) patients had higher sCD40L, P-selectin, TFPI, and D-dimer than 28 healthy controls, and these increased during 1-week follow-up, while TFPI decreased; (2) tocilizumab attenuated P-selectin in patients with short symptom duration at 24 hours in particular in those with high C-reactive protein, and this change correlated positively with indices of myocardial damage; (3) tocilizumab augmented TF at 168 hours, and this change correlated positively with infarct size and negatively with myocardial salvage index; (4) change in D-dimer at 168 hours correlated positively with infarct size and negatively with myocardial salvage index in particular in those with long symptom durations or treated with placebo; tocilizumab attenuated these changes; and (5) the use of heparin attenuated sCD40L levels and increased TFPI levels in admission samples and TF levels after 168 hours. CONCLUSIONS: Our findings support attenuation of platelet activation/coagulation by tocilizumab in patients with ST-segment-elevation MI. The marked rise in TF could be a hereto unrecognized side effects of tocilizumab, which need further investigation.