A systematic review of Anakinra, Tocilizumab, Sarilumab and Siltuximab for coronavirus-related infections

Khan, Fasihul; Fabbri, Laura; Stewart, Iain; Robinson, Karen; Smyth, Alan R; Jenkins, Gisli

Background There is accumulating evidence for an overly activated immune response characterised by the release of pro-inflammatory cytokines in severe Covid-19. Suppression of the inflammatory response with immunomodulatory therapies may be a potential therapeutic strategy. We systematically review and assess the effectiveness of specific interleukin-1 and -6 inhibitors for the treatment of coronavirus-related infections. Methods Electronic databases, pre-print servers and clinical trial registries were searched to identify current and ongoing studies of immunomodulatory agents (anakinra, sarilumab, siltuximab and tocilizumab) for the treatment of Covid-19 and other coronavirus related super infections. The co-primary outcome was time to hospital discharge (days) and severity on an ordinal scale measured at day 15. Results Five retrospective studies (tocilizumab, two case series and two case reports; siltuximab, one case series) were shortlisted for inclusion, totalling 59 patients. All studies had a moderate or high risk of bias, with multiple limitations. Insufficient data and inter-study heterogeneity prevented meta-analysis. Primary outcomes were inconsistently reported but suggest many patients experienced an improvement in status seven days following therapy. The case fatality ratio (CFR) of patients with severe Covid-19 included in our review was 6.8%, a figure substantially lower than that estimated in non-interventional case series. Of the studies measuring IL-6, all reported elevated baseline levels. Twenty-five ongoing registered clinical trials exploring immunomodulatory agents in Covid-19 were identified, although inconsistency in participants and endpoints are noted. Conclusion Inhibition of IL-6 with tocilizumab and siltuximab requires further evaluation in managing the assumed hyperinflammatory response associated with severe Covid-19. These early data are considered hypothesis generating and justify the need for well-designed randomised clinical studies.