STAT3 and rheumatoid arthritis: In particular, since its approval in 2009, tocilizumab has been used to inhibit IL-6/STAT3 signaling in autoimmune diseases, such as rheumatoid arthritis, caused by the overexpression of IL-6 and acute inflammatory diseases caused by cytokine storms associated with chimeric antigen receptor T-cell therapy and SARS-CoV-2 infection, and it has shown high therapeutic efficacy against various immune diseases.