Abstract
This study evaluated the real-world effectiveness of belimumab (BLM) in the treatment of systemic lupus erythematosus (SLE) patients with moderate to high disease activity. This retrospective cohort study enrolled 129 Japanese patients with moderate to high SLE disease activity who received BLM between January 2013 and March 2023. The clinical outcomes, including the flare-free survival, SLE Disease Activity Index 2000 (SLEDAI-2K) score, and prednisone-equivalent dose, in the BLM and mycophenolate mofetil (MMF) treatment groups were compared before and after treatment. Safety data for BLM were collected. Additionally, we compared the effectiveness of BLM and intravenous cyclophosphamide (IV-CY) treatment using the stabilized inverse probability of treatment weighting (IPTW) method based on the propensity scores. This observational study enrolled 129 patients with moderate/severe SLE: 48 patients received belimumab, 45 received IV-CY, and 36 received MMF and prednisolone for remission induction therapy. The median follow-up for the BLM group was 17.0 months. Among them, 19 received BLM plus MMF. BLM significantly reduced the mean SLEDAI-2K (from mean baseline to 52 weeks: 49.2% reduction from 12.8 to 6.5) and prednisone daily dose (from mean baseline to 52 weeks: 21.9% reduction from 12.8 to 10.0 mg/day). The flare-free survival at 52 weeks was not significantly different between the BLM and MMF groups. There was no significant difference in the flare-free survival rates or reduction rates of the SLEDAI-2K between the patients treated with BLM and those treated with BLM plus MMF. In the propensity score-matched comparative analyses, there was no significant difference in the flare-free survival rates or an estimated decline in the SLEDAI-2K scores between the patients with lupus treated with BLM and IV-CY. BLM may be a promising alternative treatment option for lupus patients with moderate or high disease activity who do not respond to conventional treatments.