Guselkumab (CNTO 1959) is a recombinant human IgG1 monoclonal antibody targeting the IL-23p19 subunit. Guselkumab binds to human cynomolgus monkey IL-23 with Kd values of 3.3 and 1.9 pmol/L, respectively. Guselkumab can inhibit the production of cytokines downstream of IL-23 signaling pathway, and can be used in the study of psoriatic arthritis.