Anifrolumab

Anifrolumab is a fully human IgG1κ monoclonal antibody that binds to subunit 1 of the type I interferon receptor (IFNAR1), blocking signaling of all type I interferons (IFN-α, IFN-β, IFN-ω). It is approved for moderately to severely active systemic lupus erythematosus (SLE) in adults receiving standard therapy. It is the first type I IFN receptor antagonist approved for SLE and addresses the interferon signature that drives SLE pathogenesis.

Anifrolumab (anifrolumab) belongs to the Type I interferon receptor antagonist / Biologic class of medications. It was first approved by the FDA in 2021. This medication requires a prescription from a licensed healthcare provider.

Anifrolumab binds with high affinity and selectivity to subunit 1 of the type I interferon receptor (IFNAR1). This blocks the binding and signaling of all type I interferons — IFN-α (13 subtypes), IFN-β, and IFN-ω — to the IFNAR1/IFNAR2 receptor complex on target cells. Type I interferons are central to SLE pathogenesis: they are produced in excess due to defective clearance of apoptotic cells and immune complexes, which activate plasmacytoid dendritic cells (pDCs) via Toll-like receptors (TLR7, TLR9). Type I IFN signaling drives maturation of dendritic cells, B cell activation and autoantibody production, T cell activation, innate immune amplification, and upregulation of autoimmune-related gene programs — collectively the 'interferon signature' detectable in blood of ~75–80% of SLE patients. By blocking IFNAR1, anifrolumab suppresses this central pathogenic amplification loop.