Background To evaluate belimumab (BLM) effectiveness in SLE patients from a Spanish multicenter registry.

Methods A longitudinal retrospective multicenter cohort including SLE patients treated with belimumab. Data collection at baseline, 6, 12 months and in the last visit available. Changes in SLEDAI-2K; LLDAS and DORIS-2021 states and response according to physician were compared between visits; also changes in damage and glucocorticoids used. T-test was used for numerical variables and the Fisher’s test for categorical variables.

Results 324 patients: 295 (91%) females with a mean (±SD) age of 42.4 (±12.9) years. Mean follow-up was 3,8 (±2.7) years and mean time with BLM was 2.7 (±2.4) years. Baseline mean SLEDAI-2K was 10.4 (±5.25). BLM was initiated with another DMARD in 67.9% of patients.

SLEDAI-2K significantly reduced in all visits. Rates of LLDAS, DORIS and clinical response according to physician criteria, significantly increased from baseline to the successive evaluations. Anti-dsDNA antibodies and inflammatory markers (ESR, CRP), significantly decreased over the time. (table 1).

107 (45,9%) patients discontinued GC. Mean (±SD) prednisone dose was significantly reduce over the visits: 12.3 (±12.16) and 4.7 (±3.7) mg/day at baseline and in the last visit, respectively (table 1). Median (IQR) SDI score at the end of the observation period did not change from baseline visit: 0 (0–1) and 0 (0–1) (p=0.97). No chanfes in the percentage of patients with damage between the beginning and the end of the study: 47.5% (n=152) and 45.6% (n=99), respectively.

Conclusions Our data confirm belimumab efficacy in real world, reducing clinical and serological activity in the short and medium-term. BLM leads to high rates of LLDAS and DORIS at 6 months, that continue increasing over time. BLM has an important GC sparing effect and prevents organ damage accrual. BLM is useful to achieve the therapeutic goals of a T2T strategy.