Attenuation of inflammatory response with IL-6 receptor antagonist in NSTEMI patients

Kleveland O, Kunszt G, Bratlie M, et al.
Eur Heart J 2016;published online ahead of print

Background

The prognosis of ACS has been associated with inflammation [1]. IL-6 is a multifunctional cytokine with an apparent causal role in CAD, since IL-6 contributes to:

• atherosclerotic plaque development and destabilisation [2,3] 
• myocardial ischemia and reperfusion injury [4] 
• increased mortality in ACS patients [1]
• activation of the C-reactive protein, a predictor of adverse outcomes in ACS [1,5]

Although there is some preclinical evidence suggesting that the disruption of IL-6 signaling could lead to an anti-atherogenic effect [6], the effects of IL-6 inhibition in human atherosclerotic disease following revascularization have not been studied.
Tocilizumab is a humanized IL-6R antibody that is effective and generally well-tolerated in patients with autoimmune disorders [7,8], and may also attenuate the acute inflammatory response in ACS and reduce TnT release.
In this randomised, controlled trial, the effect of short-time inhibition of IL-6 signaling with tocilizumab in 117 patients with NSTEMI was evaluated.

Main results

• The median area under the curve (AUC) for high-sensitivity C-reactive protein during hospitalisation was 2.1 times higher in the placebo compared with the tocilizumab group (4.2 vs. 2.0 mg/L/h; P < 0.001).
• The median AUC for hsTnT during hospitalisation was 1.5 times higher in the placebo group compared with the tocilizumab group (234 vs. 159 ng/L/h; P = 0.007).
• The differences between the two treatment groups were observed mainly in patients included ≤2 days from symptom onset and patients treated with PCI

 IL-6 levels:

• in the tocilizumab group there was a pronounced increase in IL-6 that persisted during hospitalisation
• in the placebo group, there was a modest but significant increase in IL-6 levels
• the between-group differences in changes from baseline were significant throughout hospitalisation
• changes of C-reactive protein were inversely correlated with changes in IL-6, only in the tocilizumab group

Biochemical parameters:

• The total leukocyte count increased in the placebo group but decreased in the tocilizumab group (from 7.7 [10⁹/L] at baseline to 4.4 at day 3; P < 0.001), resulting in significant between-group differences in changes from baseline (P < 0.001). This difference was mainly driven by a decrease in neutrophils in patients receiving tocilizumab, but levels returned to normal during the long-term follow-up
• There were modest between-group differences in changes from baseline in alanine aminotransferase and total cholesterol during hospitalisation, but there were no between-group differences at follow-up

Conclusion

In 117 patients with NSTEMI, short-time inhibition of IL-6 with tocilizumab attenuated the inflammatory response and primarily PCI-related TnT release, suggesting a link between inflammation and myocardial injury in these patients. There were no major safety concerns.
An increase in IL-6 levels has also been observed in autoimmune patients treated with tocilizumab and may reflect attenuated elimination of IL-6 from the circulation, as IL-6 receptor interaction is blocked and thereby IL6-R-mediated clearance [9].

Find this article online at Eur Heart J

References

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