Objective: This extension study of the Phase III, randomized, placebo-controlled Belimumab International SLE Study (BLISS)-52 and BLISS-76 studies allowed non-US patients with SLE to continue belimumab treatment, in order to evaluate its long-term safety and tolerability including organ damage accrual.
Methods: In this multicentre, long-term extension study (GlaxoSmithKline Study BEL112234) patients received i.v. belimumab every 4 weeks plus standard therapy. Adverse events (AEs) were assessed monthly and safety-associated laboratory parameters were assessed at regular intervals. Organ damage (SLICC/ACR Damage Index) was assessed every 48 weeks. The study continued until belimumab was commercially available, with a subsequent 8-week follow-up period.
Results: A total of 738 patients entered the extension study and 735/738 (99.6%) received one or more doses of belimumab. Annual incidence of AEs, including serious and severe AEs, remained stable or declined over time. Sixty-nine (9.4%) patients experienced an AE resulting in discontinuation of belimumab or withdrawal from the study. Eleven deaths occurred (and two during post-treatment follow-up), including one (cardiogenic shock) considered possibly related to belimumab. Laboratory parameters generally remained stable. The mean (s.d.) SLICC/ACR Damage Index score was 0.6 (1.02) at baseline (prior to the first dose of belimumab) and remained stable. At study year 8, 57/65 (87.7%) patients had no change in SLICC/ACR Damage Index score from baseline, indicating low organ damage accrual.
Conclusion: Belimumab displayed a stable safety profile with no new safety signals. There was minimal organ damage progression over 8 years.
Keywords: belimumab; long-term treatment; organ damage; safety; systemic lupus erythematosus.
© The Author(s) 2019. Published by Oxford University Press on behalf of the British Society for Rheumatology.