Effect of belimumab in patients with systemic lupus erythematosus treated with low dose or no corticosteroids

Background/Aims: Systemic lupus erythematosus (SLE) responder index (SRI)-4 response has been achieved with belimumab treatment in patients with moderate disease activity in cornerstone clinical trials and following studies. However, most studies involved patients treated with a mean prednisolone-equivalent dose of approximately 10 mg/d and focused on the steroid-sparing effect of belimumab. We aimed to identify the effect of belimumab in patients with mild-to-moderate SLE who were treated with low-dose or no corticosteroids. Methods: We retrospectively reviewed the electronic medical records of patients treated with belimumab for at least 6 months between May 2021 and June 2022. The primary endpoint was SRI-4 response at 6 months. Results: Thirty-one patients were included (13 low dose-and 18 steroid non-users). The mean age was 39.2 +/- 11.4 years, and 90.3% of patients were female. The baseline Safety of Estrogens in Lupus Erythematosus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) score was 6.0 (4.0-9.0). The primary endpoint was achieved in 32.3% (10/31) of patients. Significant improvements in anemia, C4 levels, and SELENA-SLEDAI score were observed during treatment. Univariate analysis showed that the baseline SELENA-SLEDAI and arthritis were significantly associated with SRI-4 response at 6 months, and only the SELENA-SLEDAI remained significant (p = 0.014) in multivariate analysis. Conclusions: This cohort study is the first to report the efficacy of belimumab after minimizing the effect of corticosteroids. Belimumab showed efficacy in improving the SELENA-SLEDAI score, anemia, and low C4 in patients who did not receive corticosteroids or received only low doses.