POS0689 A 6-MONTH OPEN-LABEL EXTENSION STUDY OF THE SAFETY AND EFFICACY OF INTRAVENOUS BELIMUMAB IN PATIENTS WITH LUPUS NEPHRITIS

Background: BLISS-LN (GSK Study BEL114054; NCT01639339 ), the largest lupus nephritis (LN) study to date, showed that intravenous (IV) belimumab (BEL) + standard therapy (ST) improved outcomes compared with ST alone in patients (pts) active LN. 1 Objectives: To assess additional safety and efficacy data of BEL pts LN a 6-month open-label (OL) phase beyond 2 years double-blind (DB) treatment BLISS-LN. Methods: In this OL phase, eligible completers DB received monthly 10 mg/kg IV for 6 months. Endpoints: safety; Primary Efficacy Renal Response (PERR; uPCR ≤0.7; eGFR no worse than 20% below baseline or ≥60 ml/min/1.73 m ; prohibited medications) Complete (CRR; <0.5; 10% ≥90 at Week 28; proportion SLEDAI score <4; corticosteroid use; biomarkers. Analyses were based on observed summarised relative (last value measured prior first dose treatment). Results: We enrolled 257 (57.4% BEL114054) treated 255 pts. All included population (123 switched from placebo [PBO] BEL; 132 remained BEL). was assessed population, excluding pt due non-compliance (mITT population; PBO BEL: 122 pts; pts). 96.5% completed phase; 3.5% withdrew, mainly adverse events (AE; 2.0%). Overall, 168/255 (65.9%) had ≥1 AE (76/123 [61.8%] 92/132 [69.7%] pts); 15/255 (5.9%) serious (5/123 [4.1%] 10/132 [7.6%] (0.8%) died group. Proportions PERR CRR responders increased 28 (Table 1. below) who attained scores <4 group decreased Among receiving average daily prednisone-equivalent doses ≤5 mg ≤7.5 maintained autoantibodies baseline, anti-dsDNA anti-C1q levels both groups. low C3/C4 groups Conclusion: BLISS-LN, proportions BEL-naïve BEL-experienced groups; new signals observed. Improvements biomarker observed, especially BEL. Funding: GSK. References: [1]Furie R, et al. N Engl J Med. 2020;383(12):1117-28. Table Responses N=254) baseline* (n=122 ) (n=132 n 118 PERR, (% 73 (59.8) † 93 (70.5) 79 (66.9) 91 (74.6) CRR, 44 (36.1) 63 (47.7) 57 (48.3) 76 (62.3) 120 Responders, 64 (48.5) 40 (33.3) (52.5) Prednisone-equivalent 121 128 mg, 59 (48.4) 78 (59.1) 60 (49.6) 75 (58.6) 62 (50.8) 85 (64.4) 66 (54.5) 83 (64.8) Anti-dsDNA (IU/ml ‡ 81 61 Median (IQR) 107.0 (49.0, 212.0) 65.5 (42.5, 126.5) - % change -30.2 (-46.3, -6.8) -10.7 (-27.2, 9.1) Anti-C1q (U/ml § 58 54 71.7 (36.6, 167.5) 47.1 (33.0, 75.7) -23.0 (-41.5, 0.5) -16.5 (-33.0, 6.1) C3 (mg/dl ‖ 45 37 35 78.0 (72.0, 83.0) 80.0 (71.0, 84.0) 6.2 (-4.2, 14.6) 4.7 (-4.8, 16.9) C4 18 12 11 7.5 (6.0, 8.0) 7.0 (7.0, 8.5) 23.6 (11.1, 37.5) 11.1 (0.0, 57.1) *DB 104 visit same visit; Post hoc analyses; positive (≥30 IU/ml); (≥22.2 U/ml); (<90 mg/dl)/C4 (<10 mg/dl) baseline. Acknowledgements: Medical writing assistance provided by Olga Conn, PhD, Fishawack Indicia Ltd., UK, part Health, funded Disclosure Interests: Richard Furie Consultant of: GSK, Grant/research support from: Brad H Rovin Frederic Houssiau UCB, Gabriel Contreras Genentech, Merck, Paula Curtis Shareholder Employee Anuradha Madan Angela Jones-Leone Mohamed Okily David Roth GSK