BACKGROUND: In adults with active lupus nephritis, the efficacy and safety of 
intravenous belimumab as compared with placebo, when added to standard therapy 
(mycophenolate mofetil or cyclophosphamide-azathioprine), are unknown.
METHODS: In a phase 3, multinational, multicenter, randomized, double-blind, 
placebo-controlled, 104-week trial conducted at 107 sites in 21 countries, we 
assigned adults with biopsy-proven, active lupus nephritis in a 1:1 ratio to 
receive intravenous belimumab (at a dose of 10 mg per kilogram of body weight) 
or matching placebo, in addition to standard therapy. The primary end point at 
week 104 was a primary efficacy renal response (a ratio of urinary protein to 
creatinine of ≤0.7, an estimated glomerular filtration rate [eGFR] that was no 
worse than 20% below the value before the renal flare (pre-flare value) or ≥60 
ml per minute per 1.73 m2 of body-surface area, and no use of rescue therapy), 
and the major secondary end point was a complete renal response (a ratio of 
urinary protein to creatinine of <0.5, an eGFR that was no worse than 10% below 
the pre-flare value or ≥90 ml per minute per 1.73 m2, and no use of rescue 
therapy). The time to a renal-related event or death was assessed.
RESULTS: A total of 448 patients underwent randomization (224 to the belimumab 
group and 224 to the placebo group). At week 104, significantly more patients in 
the belimumab group than in the placebo group had a primary efficacy renal 
response (43% vs. 32%; odds ratio, 1.6; 95% confidence interval [CI], 1.0 to 
2.3; P = 0.03) and a complete renal response (30% vs. 20%; odds ratio, 1.7; 95% 
CI, 1.1 to 2.7; P = 0.02). The risk of a renal-related event or death was lower 
among patients who received belimumab than among those who received placebo 
(hazard ratio, 0.51; 95% CI, 0.34 to 0.77; P = 0.001). The safety profile of 
belimumab was consistent with that in previous trials.
CONCLUSIONS: In this trial involving patients with active lupus nephritis, more 
patients who received belimumab plus standard therapy had a primary efficacy 
renal response than those who received standard therapy alone. (Funded by 
GlaxoSmithKline; BLISS-LN ClinicalTrials.gov number, NCT01639339.).