EMBRACE: Phase 3/4, Randomized, 52-Week Study of Belimumab Efficacy and Safety in Patients of Black African Ancestry With Systemic Lupus Erythematosus

Objective Enrollment of patients of Black African ancestry with systemic lupus erythematosus (SLE) in Phase 2 and 3 belimumab trials was not reflective of the racial distribution observed in the lupus population. This study assessed efficacy and safety of intravenous (IV) belimumab plus standard therapy in patients of self-identified black race. Methods EMBRACE (GSK Study BEL115471; NCT01632241): 52-week multicenter, double-blind (DB), placebo-controlled trial in adults of self-identified black race with active SLE, receiving monthly belimumab 10 mg/kg IV, or placebo, plus standard therapy. The optional 26-week open-label extension phase included patients who completed the DB phase. The primary endpoint was SLE Responder Index response rate at Week 52 with modified proteinuria scoring adapted from the SLEDAI-2K (SRI-S2K). Key secondary endpoints included: Week 52 SRI response rate, time to first severe flare, and reductions in prednisone dose. Results The modified intention-to-treat population comprised 448 patients (96.9% female; mean [standard deviation] age: 38.8 [11.42] years). The primary endpoint (SRI-S2K response rate at Week 52) was not achieved (belimumab 48.7%, placebo 41.6%; p=0.1068); however, numerical improvements favoring belimumab were observed, especially in patients with high baseline disease activity or renal manifestations. The safety profile of belimumab was generally consistent with previous SLE trials. Adverse events were the primary reason for DB phase withdrawals (belimumab 5.4%; placebo 6.7%). Conclusions The primary endpoint of this study was not achieved, but improvement with belimumab versus placebo was observed, suggesting that belimumab remains a suitable treatment option for SLE management in patients of Black African ancestry.