Tocilizumab in patients with COVID-19: which patient, time, and dose?

Tocilizumab (TCZ) is a recombinant anti-interleukin-6 monoclonal antibody which showed uprising evidence as an anti-inflammatory agent which modulates the cytokine storm in patients with COVID-19. However, proper use of the drug requires selection of the appropriate patient and timing. The two main factors which might improve patient selection are the degree of respiratory failure and systemic inflammation. TCZ can decrease the mortality and progression to invasive mechanical ventilation in patients with severe COVID-19 who are not yet invasively ventilated. However, its use in invasively ventilated patients did not yet gain the same level of evidence especially when administered after > 1 day from mechanical ventilation. Being an anti-inflammatory and immunomodulatory drug, TCZ was mostly used in patients with COVID-19 who have clear signs of cytokine storm. However, the drug still showed positive response in some studies which did not strictly select patients with elevated markers of systemic inflammation. Thus, it is warranted to investigate and/or re-analyze the role of the drug in patients with severe COVID-19 and with no signs of systemic inflammation. TCZ is used in a dose of 8 mg/kg which can be repeated if there was no clinical improvement. However, there are no clear criteria for judgment of the success of the first dose. Being a drug with a major effect on gross outcomes in a serious pandemic with millions of mortalities, TCZ should be meticulously investigated to reach definitive indications and number of doses to avoid drug overuse, shortage, and side effects.