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

Objective: To investigate predictors of response, remission, low disease activity, damage, and drug discontinuation in patients with systemic lupus erythematosus (SLE) who were treated with belimumab. Methods: In this retrospective study of a multicenter cohort of SLE patients who received intravenous belimumab, the proportion of patients who achieved remission, low disease activity, and treatment response according to the SLE Responder Index 4 (SRI-4) was determined, and the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI) was used to score disease damage yearly over the follow-up. Predictors of outcomes were analyzed by multivariate logistic regression with the results expressed as odds ratios (ORs) and 95% confidence intervals (95% CIs). Results: The study included 466 patients with active SLE from 24 Italian centers, with a median follow-up period of 18 months (range 1–60 months). An SRI-4 response was achieved by 49.2%, 61.3%, 69.7%, 69.6%, and 66.7% of patients at 6, 12, 24, 36, and 48 months, respectively. Baseline predictors of response at 6 months included a score of ≥10 on the SLE Disease Activity Index 2000 (SLEDAI-2K) (OR 3.14 [95% CI 2.033–4.860]) and a disease duration of ≤2 years (OR 1.94 [95% CI 1.078-3.473). Baseline predictors of response at 12 months included a score of ≥10 on the SLEDAI-2K (OR 3.48 [95% CI 2.004–6.025]) and an SDI score of 0 (OR 1.74 [95% CI 1.036–2.923]). Baseline predictors of response at 24 months included a score of ≥10 on the SLEDAI-2K (OR 4.25 [95% CI 2.018–8.940]) and a disease duration of ≤2 years (OR 3.79 [95% CI 1.039–13.52]). Baseline predictors of response at 36 months included a score of ≥10 on the SLEDAI-2K (OR 14.59 [95% CI 3.54–59.79) and baseline status of current smoker (OR 0.19 [95% CI 0.039–0.69]). Patients who were in remission for ≥25% of the follow-up period (44.3%) or who had low disease activity for ≥50% of the follow-up period (66.1%) accrued significantly less damage (P = 0.046 and P = 0.007). A baseline SDI score of 0 was an independent predictor of achieving low disease activity in ≥50% of the follow-up period and remission in ≥25% of the follow-up period. Our findings suggest that the lower the baseline damage, the greater the probability of achieving remission over the course of ≥25% of the follow-up. Further, there was a negative association between the number of flares reported prior to belimumab initiation and the frequency of belimumab discontinuation due to inefficacy (P = 0.009). Conclusion: In patients with active SLE and low damage at baseline, treatment with belimumab early in the disease may lead to favorable outcomes in a real-life setting.