Abstract
Novel coronavirus disease 2019 (COVID-19) emerged in late December 2019 in Wuhan, China. Since then, COVID-19 has become a pandemic affecting more than 4.1 million people worldwide. Patients with COVID-19 have a wide spectrum of manifestations, one being cytokine release syndrome (CRS) and its fatal correlate, secondary hemophagocytic lymphohistiocytosis (sHLH). Anti-cytokine therapy such as tocilizumab, an IL-6 receptor antagonist, is a potential treatment for COVID-19; however, data regarding the efficacy of this anti-IL-6 therapy are currently lacking. We report two cases of patients who received a diagnosis of COVID-19 complicated by CRS and were treated with tocilizumab. Both patients progressed to sHLH despite treatment with tocilizumab, and one developed viral myocarditis, challenging the safety and clinical usefulness of tocilizumab in the treatment of COVID-19-induced CRS. These cases highlight the need for clinical trials to determine optimal patient selection and timing for the use of tocilizumab during this disease process.