10  Anti-IL-6 receptor antibodies – Tocilizumab and Sarilumab
IL-6 is a pleiotropic, pro-inflammatory cytokine produced by a variety of cell types, including lymphocytes, monocytes, and fibroblasts. Infection by the related SARS-CoV induces a dose-dependent production of IL-6 from bronchial epithelial cells. Elevations in IL-6 levels may be an important mediator when severe systemic inflammatory responses occur in patients with SARS-CoV-2 infection. COVID-19-associated systemic inflammation and hypoxic respiratory failure is associated with an acute cytokine release, as indicated by elevated blood levels of IL-6, C-reactive protein (CRP), D-dimer, and ferritin [[114], [115], [116]]. Few clinical studies aiming to evaluate the efficacy of anti-IL-6 receptor blocker have been published so far. In a report from China by Xu et al. the authors were able to show that tocilizumab effectively improved clinical symptoms as well as reversed the deterioration of sever Covid-19 patients [117]. Within 5 days after tocilizumab, 15 of the 20 patients had lowered their oxygen intake and 19 of the 20 showed a noticeable improvement in the CT of the lungs, as well as a significant reduction in CRP levels which was noted in 16 of the 19 patients. All patients have been discharged on an average of 15 days after the tocilizumab dosing. Even though this is a small and uncontrolled study, the results seem to be impressive. Over 20 randomized controlled trials with tocilizumab, or sarilumab as well as JAK-inhibitors as baricitinib, are underway.