Elevated levels of inflammatory molecules have been correlated with increased mortality in COVID-19 patients. These inflammatory molecules—cytokines—tell immune cells to travel into damaged or infected tissue. Having a large amount of cytokines, in what is commonly described as a “cytokine storm,” causes the recruitment and hyperactivation of a large number of immune cells that may then attack and damage our own tissue. It is possible, then, that targeting cytokines and their pathways may decrease both time to recovery and mortality in COVID-19 patients. A key inflammatory molecule in cytokine storms is interleukin-6 (IL-6), which is targeted by existing arthritis drugs. A recent January 7 study led by Anthony Gordon at Imperial College London evaluated the effect of two such arthritis drugs, tocilizumab and sarilumab.
Tocilizumab and sarilumab are both antibodies that bind to IL-6 receptors and thereby block signaling by IL-6. The study, not yet peer-reviewed, included 792 patients in the final analysis and found that mortality decreased from 35.8% with standard treatment to 28.0% with tocilizumab treatment and 22.2% with sarilumab treatment (though the sarilumab-treated group was a tenth the size of the other groups). Rephrased, the mortality rate was reduced by 7.8% with tocilizumab and 13.6% with sarilumab treatment. This suggests that out of every 13 patients, one additional life will be saved by early tocilizumab administration (or, for sarilumab, one out of every 7 patients). Based on this study, the UK National Health Service authorized the use of tocilizumab and sarilumab for the treatment of COVID-19 in the intensive care setting. The US Food and Drug Administration has not yet followed suit.
This is not to say that the data is clear on tocilizumab. A peer-reviewed study published the same day in the New England Journal of Medicine found tocilizumab treatment for COVID-19 pneumonia did not affect patient survival in a group of 389 patients. An earlier study in the same journal also found an insignificant effect from tocilizumab treatment in 243 patients hospitalized with moderate COVID-19. While science can be unclear or conflicting at times, especially when studying an emerging disease like the coronavirus, researchers are always following up on promising drug candidates to ultimately deliver the best COVID-19 treatment possible.
Professor Anthony Gordon is Chair in Anaesthesia and Critical Care at Imperial College London.
Managing Correspondent: Edward Chen
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