FC 034SAFETY AND EFFICACY OF INTRAVENOUS BELIMUMAB IN PATIENTS WITH LUPUS NEPHRITIS: A 6-MONTH OPEN-LABEL EXTENSION

Abstract Background and Aims Lupus nephritis (LN) is the most common severe manifestation of systemic lupus erythematosus (SLE), occurring in up to 40% patients (pts) with SLE over their disease course, resulting 10–20% pts progressing end-stage kidney disease.1-3 The BLISS-LN (GSK Study BEL114054; NCT01639339) study demonstrated that addition intravenous (IV) belimumab (BEL) standard therapy (ST) active LN significantly improved renal responses 2 years compared ST alone.4 Here we present additional safety efficacy data from 6-month open-label (OL) extension phase BLISS-LN. Method In this OL phase, eligible completers Phase 3 (those who received BEL or placebo [PBO] through Week 100 completed 104 assessments) 10 mg/kg IV plus every 28 days for 24 weeks. Endpoints at included: safety; Primary Efficacy Renal Response (PERR; defined as urine protein:creatinine ratio [uPCR] ≤0.7; eGFR no more than 20% below baseline value ≥60 ml/min/1.73m2; rescue therapy); Complete (CRR; uPCR <0.5; 10% ≥90 uPCR; eGFR; proportion Systemic Erythematosus Disease Activity Index (SLEDAI) score <4; International Collaborating Clinics/American College Rheumatology Damage (SDI); corticosteroid use. Analyses were based on observed summarised relative (last available measured prior dosing before date first treatment dose). Results Of 257 (57.4 % double-blind [DB] study) screened enrolled, 255 treated (safety population: 123 switched PBO BEL; 132 remained BEL). total, 254 included analyses (PBO BEL: 122 pts; pts). Mean (standard deviation) age was 35.9 (10.3) years. 3.5% withdrew mainly due adverse events (AE; 2.0%). Overall, 168/255 (65.9%) experienced ≥1 AE (76/123 [61.8%] 92/132 [69.7%] pts); 49/255 (19.2%) had treatment-related (25/123 [20.3%] 24/132 [18.2% ] 15/255 (5.9%) serious (5/123 [4.1%] 10/132 [7.6%] 1 death reported group. achieving PERR CRR increased both groups (Table). median (interquartile range [IQR]) maintained SLEDAI <4 responders group tended increase 28, decrease SDI worsening (change >0) by 7 (2.9%) (4 [3.3%] [2.5%] BEL) baseline. There appreciable change number receiving average daily prednisone-equivalent doses ≤5 mg ≤7.5 Conclusion well tolerated an add-on ST, new signals. among randomised during DB phase. funding GSK. Editorial assistance (GSK-funded): Olga Conn, PhD, Fishawack Indicia Ltd., part Health, UK.