Chronic activation of the type I interferon (IFN) pathway plays a critical role in systemic lupus erythematosus (SLE) pathogenesis. Anifrolumab is a human monoclonal antibody to the type I IFN receptor subunit 1, which blocks the action of type I IFNs. Two phase 3 studies (TULIP-1 and TULIP-2) and a phase 2b study (MUSE) provide substantial evidence for the efficacy and safety of anifrolumab for moderately to severely active SLE. In all three studies, monthly intravenous anifrolumab 300 mg was associated with treatment differences >16% compared with placebo at Week 52 in British Isles Lupus Assessment Group-based Composite Lupus Assessment response rates. The combined data across a range of other clinically significant endpoints (e.g. oral corticosteroid reduction, improved skin disease, flare reduction) further support the efficacy of anifrolumab for SLE treatment. The safety profile of anifrolumab was generally similar across all studies; serious adverse events occurred in 8-16% and 16-19% of patients receiving anifrolumab and placebo, respectively. Herpes zoster incidence was greater with anifrolumab (≤7%) vs placebo (≤2%). Evidence from these clinical trials suggests that in patients with active SLE, anifrolumab is superior to placebo in achieving composite endpoints of disease activity response and oral corticosteroid reduction.