What are the main factors affecting the outcome of tocilizumab therapy in COVID-19-induced cytokine release syndrome?

Recommendations for the treatment of cytokine release syndrome/macrophage activation syndrome (MAS) associated with coronavirus disease-2019 (COVID-19) are still of poor quality. IL-6 is an important therapeutic target as a main mediator of cytokine storm. The aim of our study was to evaluate the tocilizumab (TCZ) efficacy and factors affecting the therapy outcome. This retrospective study included 27 patients treated with TCZ for COVID-19-MAS. All patients in this study were treated with TCZ (intravenously, at a dose of 8 mg kg1 ) in addition to standard therapy. Clinical improvement (survival and decreased oxygen demand) on the 10-14th days and secondary infection rate were assessed. In our 27 treated patients, 14 (51.8%) received TCZ in the intensive care unit (ICU) and seven (25.9%) were need to invasive mechanical ventilation (IMV). Fifteen (55.6%) of these patients revealed a good clinical response (four patients discharge from the ICU and 11 patients who followed-up in nonICU beds showed a decrease in oxygen demand). TCZ was significantly less effective in patients having high Murray lung injury score, low PO2/FiO2 ratio, IMV, and ICU admission (P < .05). Severity of hypoxemia was found as a single independent risk factor in the multivariable analysis (P < .05). Secondary bacterial infections rate was significantly higher in intubated patients (P < .01) or treated in the ICU (P ¼ .01). TCZ was showed limited efficacy for COVID-19-related MAS. The most important predictive indicator for therapy outcome was found as the severity of hypoxemia. In addition, IMV and/or ICU was associated with the poor outcome and high side effect. So, controlled trials are still needed to confirm the indications and timing of TCZ therapy.