Why do some patients with systemic lupus erythematosus fail to respond to B-cell depletion using rituximab?

OBJECTIVES: The Centre for Rheumatology has treated 165 lupus patients with rituximab (RTX) since 2000. Our aim was to identify patients who failed to respond, identify any obvious distinguishing features, and to optimise individual patient treatment. METHODS: We reviewed all 165 lupus patients treated with RTX and reviewed the data up to 6 months after treatment. We excluded those who developed allergic reactions, had discoid lupus only or were lost to follow-up. We assessed patients with active disease after 6 months, using the British Isles Lupus Assessment Group (BILAG) disease activity scores. Those patients whose A and B scores did not decrease, were deemed to have failed to respond. RESULTS: 144 patients were included in the final analysis. The median disease duration was 6.68 (IQR 2.32-11.90) years. 13.9% of the patients failed to decrease their BILAG scores. Two of the 144 patients died during the 6 months after treatment. The median BILAG at baseline was lower in the failure group (8.50, SD 6.00-12.75) at the time of treatment as opposed to those patients who improved (17, SD12.0-23.0) (p<0.001).We found that patients with renal involvement failed less often than those without it (p=0.021). No other significant differences were observed. CONCLUSIONS: Patients with a lower BILAG score are less likely to benefit from RTX treatment. Patients with renal involvement were less likely to fail to respond to RTX. We could not identify other features predictive of failure.