Background We investigated the 2-year outcomes of belimumab (BEL) additive on standard of care (SoC) in patients with SLE in the real-world setting.

Methods Sixty-four SLE patients treated with BEL additive to SoC for 2 years (BEL+SoC) and 341 patients treated with SoC were recruited. The patient backgrounds were adjusted with propensity score matching; 11 items including age, sex, disease activity, glucocorticoid (GC) dose, rash, alopecia, arthritis, anti-dsDNA antibody, hypocomplementemia, urinary and blood cell count abnormality, and 33 patients in each group remained for analysis. Disease activity was measured by SLE disease activity scale (SLEDAS).

Results The median SLEDAS at 2 years was significantly decreased from baseline in BEL+SoC (2.08 to 1.12, p<0.001) but not in SoC (2.09 to 2.03, p=0.058). Low disease activity was achieved with significant difference in BEL+SoC compared to SoC (29 (88.8%) vs 17 (51.5%), p=0.023) without difference in remission rate (72.7% vs. 51.5%, p=0.127). Median daily prednisolone (PSL) dose at 24 weeks significantly decreased in both treatment groups from baseline (BEL+SoC; 6.0 to 3.5 mg/day, p<0.001, SoC; 5.0 to 4.0 mg/day, p<0.001) without a statistical difference (p=0.112). However, absolute reduction was significant in BEL+SoC (-3.0mg) compared to SoC (-1.0mg) (p=0.004). Disease recurrence occurred in 5 (15.2%) patients in BEL+SoC and 4 (12.1%) in SoC (p=0.714). All recurrences in patients with BEL+SoC were experienced after 10 months and later during PSL tapering. Whereas those in SoC occurred from one month and later, which did not always relate to PSL tapering.

Conclusions Add-on treatment with BEL was effective to achieve low disease activity during PSL tapering which would lead to reducing GC related organ damages. However, recurrence was observed in both groups indicating the need for GC tapering strategies in an individual setting.