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Type I Interferon Receptor Antagonist (Monoclonal Antibody) Pregnancy: Avoid — no adequate human data; IFN type I plays a role in immune tolerance in pregnancy; discontinue if pregnancy occurs.

Anifrolumab (Type I IFN Receptor Inhibitor — SLE)

Brand names: Saphnelo

Adult dose

Dose: 300 mg IV every 4 weeks (30-minute infusion)
Route: IV infusion over 30 minutes
Frequency: Every 4 weeks
Max: 300 mg per infusion
Blocks the IFNAR1 subunit of the type I IFN receptor — prevents IFN-α/β signalling that drives SLE pathogenesis. Approximately 70–80% of SLE patients have elevated type I IFN signature — these 'IFN-high' patients show greatest benefit. MHRA approved 2022 for moderate-severe SLE on background standard of care. Does NOT cover lupus nephritis (limited nephritis data).

Paediatric dose

Route:
Not licensed in paediatrics.

Dose adjustments

Renal

No dose adjustment required.

Hepatic

No dose adjustment required.

Clinical pearls

  • TULIP-2 trial (Morand et al. NEJM 2020): anifrolumab 300 mg vs placebo — BICLA response rate 47.8% vs 31.5% (p=0.001); sustained steroid reduction achieved in 51% vs 30%. Type I IFN signature status (high vs low) predicts response — IFN-high patients showed greater benefit. Mechanistically superior in musculoskeletal and cutaneous SLE
  • IFN signature testing: approximately 70–80% of SLE patients have elevated IFN signature by gene expression. MHRA label does not mandate IFN testing before use (unlike some trials), but it helps predict responders. IFN-low patients may benefit less
  • Shingles prevention protocol: all patients should receive non-live recombinant zoster vaccine (Shingrix 2-dose schedule) before initiating anifrolumab; if vaccine cannot be given first, give as soon as possible after starting; monitor closely for zoster reactivation throughout treatment

Contraindications

  • Active untreated hepatitis B (IFN blockade may allow viral reactivation)
  • Active serious infection
  • Live vaccines (during and for 3 months after — IFN is critical for antiviral immunity)

Side effects

  • Respiratory infections (upper and lower respiratory tract infections — IFN type I is key antiviral defence; shingles increased)
  • Herpes zoster (varicella-zoster reactivation — significant risk: 7% vs 1.5% placebo; offer shingles vaccination before starting)
  • Nasopharyngitis
  • Infusion-related reactions (rare — pre-medicate with antihistamine)
  • Hypersensitivity reactions
  • Cough

Interactions

  • Live vaccines (absolute — IFN suppression; no live vaccines during treatment)
  • Other immunosuppressants (additive infection risk)
  • Herpes zoster vaccine (recombinant/inactivated vaccine Shingrix can be given — non-live)

Monitoring

  • SLEDAI (SLE Disease Activity Index) at each visit — response assessment
  • Prednisone dose (steroid-sparing achievement)
  • Infections (especially herpes zoster — monthly skin/pain assessment)
  • Vaccination status (ensure non-live vaccines up to date)
  • Complement C3/C4 and anti-dsDNA (disease biomarkers)

Reference: BNFc; BNF 90; Morand et al. NEJM 2020 (TULIP-2 trial); MHRA Approval Saphnelo 2022; NICE Appraisal; BSR SLE Guidelines 2023. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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