Early disease and low baseline damage predict response to belimumab in patients with systemic lupus erythematosus.

To investigate predictors of response, remission, low disease activity (LDA), damage and drug discontinuation in patients with systemic lupus erythematosus (SLE) treated with belimumab.We retrospectively analysed data of a multicentre cohort of SLE patients receiving intravenous belimumab. Proportion of patients achieving remission, LDA and SLE Responder Index-4 (SRI-4) were evaluated. SLICC damage index (SDI) was calculated yearly. Predictors of outcomes were investigated by multivariate logistic regression.We included 466 active SLE patients from 24 Italian centres: median (range) follow-up 18 (1-60) months. SRI-4 was achieved by 49.2%, 61.3%, 69.7%, 69.6% and 66.7% patients at 6, 12, 24, 36 and 48 months. Baseline predictors of response at 6 months were SLEDAI-2K≥10 (OR 3.14, 95%CI 2.033-4.860) and disease duration≤2 years (OR 1.94, 95%CI 1.078-3.473); at 12 months SLEDAI-2K≥10 (OR 3.48, 95%CI 2.004-6.025), SDI=0 (OR 1.74, 95%CI 1.036-2.923); at 24 months SLEDAI-2K≥10 (OR 4.25, 95%CI 2.018-8.940), disease duration ≤2 years (OR 3.79, 95%CI 1.039-13.52); at 36 months SLEDAI-2K≥10 (OR 14.59, 95%CI 3.54-59.79) and baseline smoking (OR 0.19, 95%CI 0.039-0.69). Patients spending≥25% follow-up in remission (42.9%) or≥50% in LDA (66.0%) accrued significantly less damage (p=0.046 and p=0.007). Baseline SDI=0 independently predicted LDA ≥50% and remission ≥25%; the lower the baseline damage, the higher the probability of remission ≥25%. Number of previous flares negatively predicted belimumab discontinuation due to inefficacy (p= 0.009) CONCLUSIONS: The early use of belimumab in patients with active SLE and low baseline damage predicts favourable outcomes in a real-life setting.