What are the indications, efficacy, and toxicities of belimumab (Benlysta)?
- • FDA-approved indication: SLE. Does not work in RA.
- • Available formulation: single-use vial containing 120 mg or 400 mg of lyophilized powder for reconstitution. A 200-mg/mL single-dose prefilled autoinjector or syringe is also available.
- • IV dosage: loading dose of 10 mg/kg IV at 0, 2, and 4 weeks; maintenance 10 mg/kg IV every 4 weeks. Does not need premedication. Infusion takes 1 hour.
- • Subcutaneous dose: 200 mg SC weekly.
- • Follow-up: routine monitoring for SLE.
- • Efficacy: SLE patients who were not responding to standard therapy achieved primary endpoint in 43%–58% of cases. Patients with severe renal and central nervous system disease were excluded from trials; thus these patients should not be primarily treated with belimumab. It seems to be most effective in patients with active serologies (low C3/C4, elevated anti-dsDNA antibody) and high BLyS levels (not available for testing). Manifestations that respond best are fatigue, rash, and arthritis. Hematologic abnormalities do not respond well. The subcutaneous as well as the IV formulation works well.
- • Adverse reactions: infections, infusion reactions, serious infections, and malignancies were not increased over placebo rate.
- • Depression and suicide mildly increased over placebo rate.
- • Immunizations: response to killed/inactivated vaccines may be decreased.
- • Precautions: do not use in patients with active infection. Can be given with background immunosuppressive therapy.
