This is a fully humanized IgG1 monoclonal antibody using the same sequences as the therapeutic antibody risankizumab. It targets IL23 for the treatment of plaque psoriasis, psoriatic arthritis, and Crohn’s disease. Risankizumab binds to the p19 subunit of IL23 with hifh affinity and neutralizes it, preventing its interaction with IL23 receptor and subsequent activation of IL23 signaling cascades. The binding of IL23 to its receptor activate the IL23/Th17 axis, which is responsible for mediating T cell-mediated immune responses and inflammation. The IL23/Th17 axis triggers the differentiation of Th17 and Th22 cells as well as the release of inflammatory cytokines and chemokines such as IL17. While playing a critical role in protection against pathogens, the IL23/Th17 axis is also involved in chronic autoimmune inflammatory disorders.