Anifrolumab is a fully human monoclonal antibody (IgG1κ) approved for the treatment of moderate-to-severe systemic lupus erythematosus (SLE). It functions as a type I interferon (IFN) receptor antagonist, specifically binding to subunit 1 of the type I IFN receptor (IFNAR1). By blocking the receptor, it inhibits the signaling of all type I IFNs (including IFN-α, IFN-β, and IFN-ω), which are central mediators of the autoimmune inflammation in SLE. Anifrolumab is administered via intravenous infusion and represents a targeted biologic therapy for patients with active, autoantibody-positive SLE who are receiving standard care.