Efficacy and Safety of Belimumab in Patients With Lupus Nephritis: Subgroup Analyses of a Phase 3 Randomized Trial in the East Asian Population

Rationale & Objective: Belimumab improved kidney outcomes in patients with active lupus nephritis (LN) in BLISS-LN, leading to its approval in the United States and the European Union. As data on treatment of East Asian patients with LN are limited, we evaluated the efficacy and safety of belimumab in the BLISS-LN East Asian subgroup. Study Design: Prespecified subgroup analysis of BLISS-LN, a phase 3, placebo-controlled, randomized 104-week trial. Setting & Participants: Adults with biopsy-proven, active LN were randomized (1:1) to belimumab or placebo, plus standard therapy. Intervention: Patients were administered intravenous belimumab 10 mg/kg, or placebo, plus standard therapy (oral glucocorticoids and either cyclophosphamide for induction followed by azathioprine for maintenance, or mycophenolate mofetil for both induction and maintenance). At the investigator's discretion, 1-3 intravenous pulses of methylprednisolone, 5001,000 mg each, could be administered during induction. Outcomes: The primary end point was primary efficacy renal response (PERR; ie, urinary protein-creatinine ratio <= 0.7 g/g, estimated glomerular filtration rate no more than 20% below preflare value or >= 60 mL/min/1.73 m(2), and no treatment failure) at week 104. Key secondary end points included complete renal response (CRR; urinary protein-creatinine ratio <0.5 g/g, estimated glomerular filtration rate no more than 10% below preflare value or >= 90 mL/min/1.73 m(2), and no treatment failure) at week 104; PERR at week 52; time to kidney-related event or death; and safety. Analytical Approach: PERR and CRR were analyzed using a logistic regression model, and time to a kidney-related event or death was analyzed using a Cox proportional hazards regression model. Results: 142 patients from mainland China, Hong Kong, South Korea, and Taiwan were included (belimumab, n = 74; placebo, n = 68). At week 104, more belimumab than placebo patients achieved PERR (53% vs 37%; OR, 1.76 [95% CI, 0.88-3.51]) and CRR (35% vs 25%; OR, 1.73 [95% CI, 0.80-3.74]). At week 52, more belimumab than placebo patients achieved PERR (62% vs 37%; OR, 2.74 [95% CI, 1.33-5.64]). Belimumab reduced the risk of a kidneyrelated event or death compared with placebo at any time (HR, 0.37 [95% CI, 0.15-0.91]). Safety was similar across treatment groups. Limitations: Small sample size and lack of formal significance testing. Conclusions: Safety and efficacy profiles were consistent with BLISS-LN overall population, supporting benefits of belimumab treatment in the East Asian subgroup with LN.