Efficacy and safety of intravenous belimumab in a subgroup of South Korean patients with systemic lupus erythematosus enrolled into a Phase 3, randomized, placebo-controlled trial in North East Asia.

Aim: This post hoc analysis evaluated the efficacy and safety of intravenous belimumab 10 mg/kg in the South Korean subgroup of patients with systemic lupus erythematosus (SLE) enrolled in the North East Asia (NEA) study (GSK Study BEL113750; NCT01345253).

Methods: NEA was a double-blind, placebo-controlled, randomized Phase 3 trial. Patients with active, autoantibody-positive SLE were randomized 2:1 to belimumab or placebo plus standard therapy administered on Days 0, 14, and 28, and then every 28 days up to Week 48. The primary efficacy endpoint in this analysis was SLE Responder Index 4 (SRI-4) response rate at Week 52, defined as the proportion of patients achieving a ≥4-point reduction in Safety of Estrogens in Lupus Erythematosus National Assessment-SLE Disease Activity Index (SELENA-SLEDAI) score, no worsening (<0.3 increase from baseline) in Physician Global Assessment, no new British Isles Lupus Assessment Group (BILAG) A domain and <2 new BILAG B domain scores.

Results: Among 100 South Korean patients enrolled in NEA, 54/66 (81.8%) belimumab- and 24/34 (70.6%) placebo-treated patients completed the double-blind phase. Significantly more belimumab- than placebo-treated patients achieved SRI-4 response at Week 52 (n = 35/66, 53.0% vs. n = 8/34, 23.5%; odds ratio [OR; 95% confidence interval (CI)]: 3.67 [1.45, 9.28]; p = .0061). The proportion of patients experiencing ≥1 adverse event was similar between groups (belimumab: n = 60/66, 90.9% vs. placebo: n = 31/34, 91.2%). No new safety signals emerged in this subgroup analysis.

Conclusion: Belimumab was efficacious for the treatment of SLE and well tolerated among the South Korean subgroup of patients from the NEA study.