Effectiveness and safety of belimumab in patients with active systemic lupus erythematosus: results from a large, nationwide, multicentric study.

Background: Belimumab is the unique biologic therapy available for patients with SLE. Objectives: To investigate effectiveness and safety of belimumab in SLE patients in clinical practice. Methods: 458 active SLE patients (ACR criteria) from 24 Italian Centers, mean±SD age 43.5±11.3 years; mean±SD disease duration 12.3±8.7 years, were treated with belimumab (10 mg/kg day 0, 14, 28 and then every 28 days), as add-on therapy. SLEDAI-2K, anti-dsDNA, C3, C4, prednisone daily dose, DAS-28, 24H proteinuria, CLASI, PGA, Fatigue (VAS 0-10) were recorded at baseline and every 6 months. Flares were defined according to SFI. Response was evaluated according to SRI-4. Statistics were performed by pairs Ttest, chi-square test and multiple logistic regression (SPSS, version 22.0). Results: Mean±SD follow-up was 21.2±15.3 months (range 3-60). Most common features treated with belimumab were articular in 67%, mucocutaneous in 55%, and renal in 17% of cases. Improvement of clinical and serological variables, including daily prednisone dosage, was observed (Table). SRI-4 is summarized in the Figure. At the end of follow-up 293 patients (66%) were still on belimumab. Most common cause of discontinuation were inadequate response (36%), AEs (31%), and pregnancy (8%). Mean number of flare during belimumab treatment compared with the corresponding period before belimumab initiation decreased (p<0.001). SLEDAI-2K 10 was an independent predictor of response by logistic regression at month 12 and 24 (p=0.003 and p=0.025). 9,998 infusions were analyzed. 784 AEs were observed in 330 patients, SAEs were 43 in 36 patients. No severe infusion reactions were observed; 16 patients had infective SAEs, and 22 non infective SAEs. Conclusion: We confirmed the effectiveness, the steroid sparing effect and good safety profile of belimumab in our cohort.