Effects of Sarilumab on Interleukin 6 Levels in Critically Ill COVID-19 Patients

An outbreak of a mutated respiratory virus that belongs to the Coronavirus family was reported in mid-December 2019, in Wuhan, China. The virus was named as severe acute respiratory syndrome coronavirus (SARS-CoV-2) and the disease was named as coronavirus disease-19 (COVID-19) by the WHO. The infection spread pandemically and by the end of October 2021,the number of confirmed cases of COVID-19 reached 244,897,472, including 4,970,435 deaths, reported by WHO. Viral genome was sequenced and published by public health information on 10th of January. COVID-19 uses the same cell entry receptor {Angiotensin converting enzyme II} (ACE2) as SARS-CoV . Recent studies have shown that IL-6 level increased in severe cases of COVID-19. IL-6 is one of the major pro-inflammatory factors that contribute to the formation of cytokine storm.Therefore, the IL-6 monoclonal antibody (mAb) directed COVID-19 therapy has been used in clinical trial in China. The main conclusion they reached was that the treatment with the IL-6 receptor antagonists ( tocilizumab (TCZ), sarilumab, sirukumab, olamkicept and levilimab) improved outcomes, including survival. TCZ is a humanized antibody that blocks both soluble and membrane-bound forms of IL-6 receptor. Sarilumab is a fully human antibody against the IL-6 receptor that binds to both soluble and membrane-bound IL-6 receptors and has the approval of the food and drug administration (FDA) for rheumatoid arthritis (RA) treatment. Additionally, these drugs have been considered for off-label use in the treatment of COVID-19.