Temporal clinical and laboratory response to interleukin-6 receptor blockade with Tocilizumab in 89 hospitalized patients with COVID-19 pneumonia

https://doi.org/10.1101/2020.06.12.20122374

Eighty nine patients with COVID-19 pneumonia and heightened systemic inflammation (elevated serum C reactive protein and interleukin-6 levels) were treated with Tocilizumab (TCZ), a human monoclonal IgG1 antibody to the interleukin-6 receptor. Clinical and laboratory improvement was seen comparing baseline and 1-2 day post-infusion indices. Among 72 patients not receiving mechanical ventilation, NEWS2 scores fell from 5 to 2 (p <0.001) C reactive protein levels fell from 95 to 14 mg/L (p <0.001) and lymphocyte counts rose from 900 to 1000/uL (p=0.036). Sixty three of 72 patients were discharged from hospital, one patient died, and 8 remained in hospital at time of writing. Among 17 patients receiving mechanical ventilation, despite a rapid decrease in CRP levels from 89 to 35 mg/L (p = 0.014) and early improvements in NEWS2 scores in 10 of 17, ten patients died and seven remain in hospital at time of writing. Overall, mortality was only seen in patients who had markedly elevated CRP levels (>30 mg/L) and low lymphocyte counts (<1000/uL) before TCZ administration. Inhibition of IL-6 activity by administration of Tocilizumab, an anti IL-6 receptor antibody is associated with rapid improvement in both CRP and lymphocyte counts and in clinical indices.

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