Efficacy and safety of belimumab in paediatric and adult patients with systemic lupus erythematosus: an across-study comparison

Objective To assess the efficacy and safety of belimumab in paediatric versus adult patients with systemic lupus erythematosus (SLE). Methods We performed across-study comparisons of patients with active SLE who received belimumab or placebo, plus standard therapy, in PLUTO (paediatric phase II) and BLISS-52, BLISS-76, BLISS-NEA and EMBRACE (adult phase III). Analysed efficacy data included Week 52 SLE Responder Index (SRI)-4 response rate (EMBRACE: SRI with modified Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) proteinuria scoring (SRI-S2K)); SRI-4 response rate (EMBRACE: SRI-S2K) according to baseline disease activity indicators (Safety of Estrogens in Lupus Erythematosus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) score; anti-dsDNA/C3/C4 levels); Week 52 SRI-6 response rate; and time to first severe flare (SELENA-SLEDAI Flare Index) over 52 weeks. Safety data were compared for all aforementioned studies along with adult LBSL02 (phase II) and BLISS-SC (phase III). Results SRI-4 response rates were similar across the paediatric and adult studies; more belimumab-treated patients achieved SRI-4 responses versus placebo (PLUTO: 52.8% vs 43.6%; BLISS-52: 57.6% vs 43.6%; BLISS-76: 43.2% vs 33.8%; BLISS-NEA: 53.8% vs 40.1%; EMBRACE: 48.7% vs 41.6%). Across all studies, SRI-4 response rates were generally greater in patients with baseline SELENA-SLEDAI scores ≥10 than in patients with baseline SELENA-SLEDAI scores ≤9. A similar proportion of belimumab-treated patients achieved SRI-6 across all studies (PLUTO: 41.2%; BLISS-52: 46.2%; BLISS-76: 33.1%; BLISS-NEA: 43.9%; EMBRACE: 37.5%). Belimumab reduced the risk of severe flare versus placebo in all studies. The incidence of adverse events was similar across all studies. Conclusions These analyses demonstrate consistent efficacy and safety of belimumab plus standard therapy across paediatric and adult patients with SLE. Trial registration numbers PLUTO (NCT01649765); BLISS-52 (NCT00424476); BLISS-76 (NCT00410384); BLISS-NEA (NCT01345253); EMBRACE (NCT01632241); BLISS-SC (NCT01484496); and LBSL02 (NCT00071487).