B cell depletion therapy in systemic lupus erythematosus: Longterm follow-up and predictors of response

Objectives: To describe the long-term clinical outcome and safety profile of B cell depletion therapy ( BCDT) in patients with systemic lupus erythematosus (SLE). It was also determined whether baseline parameters can predict the likelihood of disease flare. Methods: 32 patients with refractory SLE were treated with BCDT using a combination protocol ( rituximab and cyclophosphamide). Patients were assessed with the British Isles Lupus Assessment Group ( BILAG) activity index, and baseline serology was measured. Flare was defined as a new BILAG 'A' or two new subsequent 'B's in any organ system. Results: Of the 32 patients, 12 have remained well after one cycle of BCDT ( median follow-up 39 months). BCDT was followed by a decrease of median global BILAG scores from 13 to 5 at 6 months ( p = 0.006). Baseline anti-extractable nuclear antigen (ENA) was the only identified independent predictor of flare post-BCDT ( p = 0.034, odds ratio = 8, 95% Cl 1.2 to 55) from multivariable analysis. Patients with low baseline serum C3 had a shorter time to flare post-BCDT ( p = 0.008). Four serious adverse events were observed. Conclusion: Autoantibody profiling may help identify patients who will have a more sustained response. Although the long-term safety profile of BCDT is favourable, ongoing vigilance is recommended.