Belimumab

Belimumab is a human monoclonal antibody that inhibits B-lymphocyte stimulator (BLyS/BAFF), a cytokine that promotes B cell survival. By neutralizing soluble BLyS, belimumab reduces the survival of autoreactive B cells and lowers circulating autoantibodies, thereby helping to control disease activity in systemic lupus erythematosus (SLE).

It is approved as an adjunct to standard therapy for active, seropositive SLE in adults and in children aged 5 years and older. It is not a cure, but can reduce lupus activity and flare risk in some patients.

Belimumab is administered by intravenous infusion or subcutaneous injection. Dosing regimens are defined in the product labeling and typically involve an initial loading period followed by maintenance doses. The drug has a relatively long half-life and pharmacokinetics are not significantly affected by mild renal or hepatic impairment; no major drug–drug interactions are expected.

Safety: Common adverse events include infusion reactions, nausea, fever, diarrhea, upper respiratory tract infections, and headache. Serious infections are a potential risk. Neuropsychiatric events, including depression, have been reported in some patients. Hypersensitivity reactions (including anaphylaxis) can occur. Belimumab should be used during pregnancy only if clearly needed, as data on safety are limited.

Regulatory status: Belimumab (brand name Benlysta) was approved by the U.S. FDA in 2011 and has subsequent approvals in other regions, including pediatric use.